Sophie Studley (200389800)

Sophie Studley

The causes and effects of

cultural eutrophication at

Quidenham Mere.

BSc Geography

Geography Dissertation 2011

Contents Page

List of Figures .......................................................................................................................................... 5

List of Tables ........................................................................................................................................... 8

Acknowledgments .................................................................................................................................. 9

Abstract ................................................................................................................................................ 10

Chapter 1: Introduction ........................................................................................................................ 11

Chapter 2: Aims and Objectives ........................................................................................................... 13

2.1. Aims ............................................................................................................................................ 13

2.2. Objectives ................................................................................................................................... 13

2.3. Hypotheses ................................................................................................................................. 14

Chapter 3: Overview of core themes .................................................................................................. 16

3.1. Eutrophication .......................................................................................................................... 16

3.2. Lake deposits ............................................................................................................................ 17

3.3. Geochemistry ........................................................................................................................... 17

3.4. Micropaleontology ................................................................................................................... 19

3.4.1. Gastropods. .................................................................................................................... 19

3.4.2. Bivalves ......................................................................................................................... 20

3.5. Summary ................................................................................................................................... 22

Chapter 4: The Study Area ................................................................................................................... 23

4.1. Site location and description .................................................................................................... 23

4.2. Site Selection ............................................................................................................................ 24

4.3. Limitations of site chosen ......................................................................................................... 24

Chapter 5: Methodology ..................................................................................................................... 25

5.1. Coring procedure ...................................................................................................................... 25

5.2. Sediment lithology .................................................................................................................... 25

5.3. Sediment composition .............................................................................................................. 26

5.4. Chronology ................................................................................................................................ 26

5.5. Geochemistry ............................................................................................................................ 27

5.6. Magnetic susceptibility ............................................................................................................. 28

5.7. Mollusc Analysis ........................................................................................................................ 29

5.8. Statistics .................................................................................................................................... 30

5.9. Limitations of methods ............................................................................................................. 31

5.10. Ethical Issues ........................................................................................................................... 32

5.11. Summary .................................................................................................................................. 32

Chapter 6: Results ................................................................................................................................ 33

6.1. Sediment Lithology .................................................................................................................... 33

6.2. Sediment composition .............................................................................................................. 33

6.3. Geochemical analysis ................................................................................................................. 36

6.4. Non-parametric analysis (1) ...................................................................................................... 37

6.5. Magnetic susceptibility ............................................................................................................. 38

6.6. Non-parametric analysis (2) ....................................................................................................... 39

6.7. Mollusc Analysis ........................................................................................................................ 39

6.8. Quantitative zonation. ............................................................................................................... 42

6.9. Non-parametric analysis (3)……….. ............................................................................................. 44

6.10. Summary ................................................................................................................................. 45

Chapter 7: Discussion ........................................................................................................................... 47

7.1. When did the eutrophication events happen at Quidenham Mere? ........................................ 47

7.1.1. The onset of the eutrophication process ...................................................................... 47

7.1.2. The onset of the restoration process ............................................................................. 47

7.1.3. Summary ....................................................................................................................... 48

7.2. Possible causes of cultural eutrophication at Quidenham Mere .............................................. 49

7.2.1. Possible causes of the medieval/ post-medieval eutrophication event ....................... 49

7.2.2. Possible causes of the second eutrophication event .................................................... 51

7.2.3. Summary……….. ............................................................................................................. 52

7.3. The effect of cultural eutrophication at Quidenham Mere upon the Mollusca phylum .......... 52

7.3.1. Bithynia tentaculata ...................................................................................................... 53

7.3.2. Gyraulus ......................................................................................................................... 53

7.3.3. Lymnaea ......................................................................................................................... 54

7.3.4. Valvata……….. ................................................................................................................. 56

7.3.5. Pisidium ......................................................................................................................... 57

7.3.6. Summary ....................................................................................................................... 57

Chapter 8: Conclusion .......................................................................................................................... 58

8.1. Summary of main finding .......................................................................................................... 59

8.2. Limitations of the study ............................................................................................................. 60

8.3. Significance of main findings ..................................................................................................... 60

8.4. Scope for further study .............................................................................................................. 61

Chapter 9: Bibliography ....................................................................................................................... 62

Chapter 10: Appendix ........................................................................................................................... 76

10.1. Methodology .......................................................................................................................... 76

10.1.1. Loss-on-ignition ........................................................................................................... 76

10.1.2. Geochemical Analysis .................................................................................................. 76

10.1.3. Molluscs Analysis ........................................................................................................ 77

10.2. Results .................................................................................................................................... 77

10.2.1. Sediment lithology ...................................................................................................... 77

10.2.2. Sediment composition ................................................................................................ 77

10.2.3. Geochemical Analysis .................................................................................................. 84

10.2.4. Magnetic Susceptibility ............................................................................................... 87

10.2.4.1. Upper Section ............................................................................................. 87

10.2.4.2. Lower Section .............................................................................................. 89

10.2.5. Mollusc Analysis .......................................................................................................... 92

10.3. Reflective Log ......................................................................................................................... 95

10.4. DSG Report Forms .................................................................................................................. 96

10.5. Interim Report ...................................................................................................................... 104

10.5.1. First Interim Report .................................................................................................. 104

10.5.2. Second Interim Report ............................................................................................. 117

10.6. Control of Substances Hazardous to Health (COSHH) .......................................................... 134

10.7. Risk Assessment Forms ........................................................................................................ 137

List of Figures

Figure 1. Diagram identifying the main stages of the eutrophication process (Triplepoint

Water Technologies, 2011) .......................................................................................... 17

Figure 2. Diagram of a generalized gastropod. The operculum is a corneous plate that

molluscs secrete over their shell opening to survive predators and periods of drought

(Ghesquiere, 2011). ................................................................................................................. 20

Figure 3. Diagram of a generalized bivalve, with the main features labelled. Note that when

the adductor muscles relax the hinge ligaments expands and the shell opens (Little,

2008).......................................................................................................................................20

Figure 4. A geological map of East Anglia, with the location of Quidenham Mere indicated

(Peglar, 1993). ......................................................................................................................... 23

Figure 5. The local topography of Quidenham Mere and the local landmarks. ..................... 23

Figure 6. Diagram of the Bartington system designed to measure the magnetic susceptibility

of sediments (Nowaczyk, 2001). The loop sensor should be a similar size to the core in order

to produce accurate results. .................................................................................................... 28

Figure 7. A mollusc acquisition curve for the QUID1 core. In order to produce an accurate

acquisition curve, 10 samples were taken from the core at each weight, and the average was

recorded. The plots reaches asymptote at 12 individuals per sample weight. It is therefore

clear that a sample of 20 g should be extracted to achieve a full species representation. .... 29

Figure 8. A comparison between Peglar’s (1993) sediment composition diagram (434 – 1240

cm) and the QUID1 sediment composition diagram (125-830cm). The coloured lines indicate

where the organic and carbonate component correspond. Silica has been recorded first to

allow a clear comparison between the organic and carbonate variables. .............................. 34

Figure 9. A diagram of the sediment lithology and sediment composition, with the

calculated dates identified. ...................................................................................................... 35

Figure 10. The geochemistry of Quidenham Mere from the Medieval Period to the present,

focussing upon the concentration of sodium and potassium. ................................................ 36

Figure 11. The magnetic susceptible elements in the sediments of Quidenham Mere ......... 38

Figure 12. Bithynia tentaculata: Belonging to the gastropod class, this is a common

prosobranch found in slow-moving, well-oxygenated lakes (Kerney, 1999). It can survive well

in lakes with high concentrations of potassium and calcium rich waters (Jokinen, 1992). .... 39

Figure 13. Gyraulus laevis: Belonging to the gastropod class, these pulmonates are

extremely common in clean, quite water (Kerney, 1999). ...................................................... 40

Figure 14. Lymnaea peregra: Belonging to the gastropod class, these pulmonates are found

in a variety of environments, such as rivers, canals and ephemeral ponds (Kerney, 1999). .. 40

Figure 15. Valvata macrostoma: Belonging to the gastropod class, these prosobranchs are

found in slow moving water, well-vegetated, calcium rich waters (Kerney, 1999). They are,

however, extremely rare in The British Isles. .......................................................................... 40

Figure 16. Valvata piscinalis: Belonging to the gastropod class, this is a common

prosobranch found in muddy or silty substrates (Kerney, (1999). Furthermore, this snail is

tolerant to oligotrophic zones and varying carbonate concentrations (Fretter and Graham,

1978; Grigorovich et al., 2005). ............................................................................................... 41

Figure 17. Pisidium sp.: Belonging to the bivalve class, this species is found in a variety of

environments (Kerney, 1999). The diagram shows a generalized Pisidium species. .............. 41

Figure 18. The concentrations of the molluscs at Quidenham Mere, divided by quantitative

zonation. The graph shows that the concentrations of the molluscs increase between the

first (800 – 685) and second (455 -325) episode of cultural eutrophication.. ........................ 44

Figure 19. Peglar’s (1993) pollen stratigraphy of Quidenham Mere. There is a rapid increase

in Cannabaceae, during the medieval period (QM–9b). After a gentle decline of

Cannabaceae, at the end of the subzone QM-9b, Cannabaceae, increases rapidly to a

maximum of 94% during the post-medieval (QM-9c) ............................................................. 49

Figure 20. A proposed explanation of the medieval/post-medieval eutrophication event at

Quidenham Mere. ................................................................................................................... 50

Figure 21. A proposed explanation of the most recent eutrophication event at Quidenham

Mere. ........................................................................................................................................ 51

Figure 22. Diagram of a Lymnaea snail with the main features labelled. ............................... 55

Figure 23. In order to survive in periods of low DO, the snail hangs suspended from the

upper surface of the water by its foot. The snail subsequently takes in oxygen by opening its

pneumostome (Clifford, 1991) ................................................................................................ 56

List of Tables

Table 1. A summary of statistical analysis performed to address aim number two. For the

Anderson-darling test, the data is normally distributed if P > 0.05. For the Spearman’s Rho

test, the two variables are statistically correlated if P < 0.05. ............................................... 37

Table 2. A summary of the statistical analyses performed on the mollusc data. For the

Anderson-darling test, the data is normally distributed if p > 0.05. For the Spearman’s Rho

test, the two variables are statistically correlated if p < 0.05. ................................................ 46

Table 3. Sediment lithology using the terminology of Troels-Smith (1955). The work of Birks

and Birks (1980) also provided additional support. ................................................................ 65

Table 4. Results from the Loss-on-ignition analysis ................................................................ 71

Table 5. Geochemistry results regarding the concentrations of potassium and sodium in the

sediment of Quidenham Mere. ............................................................................................... 73

Table 6. Magnetic susceptibility results from the upper section of the core ......................... 76

Table 7. Magnetic susceptibility results from the lower section of the core. ......................... 78

Table 8. Results from the mollusc analysis. Concentrations of molluscs are in the following

units: concentration per 20g ................................................................................................... 81

9

Acknowledgements

Many thanks go to Ian Lawson for his invaluable help and support during this project. I

would also like to thank John Corr for his assistance during the preparation and

identification of numerous mollusc species. I would like to express my gratitude to Martin

Gilpin and Rachel Gasior for their patience whilst teaching me laboratory methods. Thanks

also go to Richard Preece, Stephen Brooks, Rosemary McIntosh and Ian McIntosh for their

interest in this project. Finally, I would like to thank Margaret and David Studley, Matthew

Fine, Nicole Bridgman and my fellow geographers for their admirable support and

encouragement.

10

Abstract

The results of a geochemical record from the top 8.3 m of sediment retrieved from

Quidenham Mere, Norfolk, are displayed. This, together with results from sediment

composition analysis and magnetic susceptibility, are used to infer and explain periods of

cultural eutrophication at Quidenham Mere since the medieval period. The effects of

cultural eutrophication upon the abundance of molluscs in the sediment have also been

discussed. Two episodes of cultural eutrophication have been determined at Quidenham

Mere. The first episode occurred during the medieval period due to hemp retting and forest

clearance. The second episode, which is a new finding, occurred within the last 200 years

due to the development of Quidenham Hall Parkland. Both of these episodes of cultural

eutrophication caused a significant rise in the concentration of molluscs, followed by a rapid

decline. The abundance of molluscs at this location, therefore, was significantly affected by

anthropogenic activities.

Keywords: cultural eutrophication; Quidenham Mere; geochemical analysis; magnetic

susceptibility; mollusc analysis

Word Count: 10,517

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Chapter 1: Introduction

“The person who does not worry about the future will shortly have worries about the

present”

Chinese Proverb

Environmental change has been a problem, on a local level, since the beginning of

civilisation. Reasons for this include population growth, agriculture, deforestation and

smelting. There is an increasing concern that anthropogenic activities, especially those

involving a change in land use, are causing a decline in biodiversity (Huggett, 2010).

Although it is extremely difficult to identify the total number of species in the world,

extinctions themselves are normally well documented (Holden, 2008). Understanding

extinctions and loss of biodiversity are therefore important topics in evaluating the effects

of anthropogenic activities.

One of the major causes of loss of biodiversity by anthropogenic activities is cultural

eutrophication. Cultural eutrophication is defined as an excessive input of nutrients and

organic material due to anthropogenic activities. A phylum which is greatly affected by

cultural eutrophication is Mollusca (Russell-Hunter, 1978). Harman and Forney (1970)

showed that eleven species of molluscs were lost from Oneida Lake after fifty years of

increased nutrient input. The molluscan productivity also significantly decreased at this

location. Bovbjerg and Ulmer (1960) and Clampitt, et al., (1960) also recognised this trend

and showed that eleven species of gastropods were lost from Lake Okoboji, Iowa, due to

changes in the trophic level of the lake. Furthermore, Morgan (1970) documented the loss

of six gastropods species from Loch Leven over the last thirty years; a lake noted for

progressive eutrophication. It is therefore clear that anthropogenic activities, which cause

eutrophication, have a deleterious effect upon the ecology of fresh waters.

The interest in cultural eutrophication however declined in the 1980s due to the heightened

interest in acidification, and many paleolimnologists altered their studies to address these

new problems (Smol, 2002). It needs to be acknowledged that cultural eutrophication is still

12

a serious problem, and is a topic that requires further work. This will enable important

questions regarding the management of this phenomenon to be answered. Battarbee, et al.,

(2005) and Cheng, et al., (2007) fully support this idea and argue that more holistic studies

need to be undertaken. Additionally, the study of ecology needs to become more predictive.

Sutherland (2006) argues that subjects such as economics and engineering are looked upon

more highly than ecology as they allow predictions to be made. It is therefore clear that

more paleolimnological work needs to be undertaken regarding cultural eutrophication, in

order to predict the course of present environmental change.

This study therefore investigates the effect of cultural eutrophication upon the abundance

of molluscs at Quidenham Mere, Norfolk. Quidenham Mere is an ideal location for this

investigation as the calcareous marl layers are abundant in molluscs. Furthermore, Cheng, et

al., (2007) documents that this location experienced cultural eutrophication during the

medieval Period. This literature will therefore contribute to the knowledge and

development in this research field.

13

Chapter 2: Aims and objectives

2.1. Aims

1) To identify and date episodes of cultural eutrophication at Quidenham Mere, Norfolk.

2) To produce possible explanations as to why Quidenham Mere experienced episodes of

cultural eutrophication.

3) To record changes in the population of molluscs in the sediment of Quidenham Mere in

response to cultural eutrophication.

2.2. Objectives

1) In order to date the core, a sediment lithology and sediment composition analysis will be

performed.

2) In order to identify and explain the episodes of cultural eutrophication at Quidenham

Mere, the concentrations of potassium (K+) and sodium (Na+) in the sediment will be

calculated and analysed.

3) The further explain the episodes of cultural eutrophication at Quidenham Mere, the

magnetically susceptible elements in the sediment will be analysed.

4) A mollusc record will be produced in order to determine the effects of cultural

eutrophication upon this phylum.

5) Appropriate statistical tests will be performed upon all of the data to prove that the

conclusions of this literature are significant.

14

2.3. Hypotheses

Five hypotheses have been investigated in this literature. These have been carefully

designed to fulfil the aims of the literature.

To fulfil the first aim of this literature the hypotheses are as follows:

1) Research Hypothesis (H1): There is a significant statistical correlation between the

potassium variable and the sodium variable.

Null Hypothesis (H0): There is not a significant statistical correlation between the organic

matter variable and the sodium variable.

To fulfil the second aim of this literature the hypotheses are as follows:

2) Research Hypothesis (H1): There a significant statistical correlation between the silica

variable and the magnetic susceptibility variable.

Null Hypothesis (H0): There is not a significant statistical correlation between the silica

variable and the magnetic susceptibility variable.

To fulfil the third aim of this literature the hypotheses are as follows:

3) Research Hypothesis (H1): There is a significant statistical correlation between the mollusc

variable and the organic variable.

Null Hypothesis (H0): There is not a significant statistical correlation between the mollusc

variable and the organic variable.

4) Research Hypothesis (H1): There is a significant statistical correlation between the mollusc

variable and the potassium variable.

Null Hypothesis (H0): There is not a significant statistical correlation between the mollusc

variable and the potassium variable.

15

5) Research Hypothesis (H1): There is a significant statistical correlation between the mollusc

variable and the sodium variable.

Null Hypothesis (H0): There is not a significant statistical correlation between the mollusc

variable and the sodium variable.

16

Chapter 3: Overview of core themes

3.1. Eutrophication

Brandt (1901) first documented the process of natural eutrophication, establishing a

relationship between the concentration of plankton and the concentration of nitrogen in

the freshwater lakes of Germany (Smith, 1998). Naumann (1919) later classified waters in

Sweden depending on their nutrient content and Pearsall (1921) documented that an

oligotrophic lake would ‘evolve’ to become a eutrophic lake. The idea of categorising a lake

by trophic states is shared with Dokulil and Teubner (2011). Nowadays the definition of

eutrophication is a much-discussed topic as highlighted by Jørgensen and Richardson (1996).

The most common use of the term, however, is related to the excessive input of mineral

nutrients and organic matter (Harper, 1992). It must also be acknowledged that when we

speak of eutrophication, it is cultural eutrophication that is of most interest, as natural

eutrophication (ontogeny) occurs with the aging process of a lake (Deevey, 1984; Andersen,

et al., 2005).

Cultural eutrophication was first acknowledged as a phenomenon post World War 2, due to

the increased need of fertilizers and pesticides (Moss, et al., 1997; Cheng, et al,. 2007).

Cultural eutrophication is an active area of scientific research, and is the most widespread

environmental problem affecting freshwaters of developed countries (Carpenter, et al.,

1998; Smith, 2003). This is due to the large number of severe problems that it can cause

(Muir, 2009). For example, the primary effect of nutrient enrichment is a change from slow

growing perennial algae (green algae) to fast growing ephemeral algae (blue-green algae)

(Dokulil and Teubner, 2011). This can lead to an increased risk of flooding and the blockage

of water filters. Furthermore, low oxygen levels can develop due to the bacterial

decomposition of algae and macrophytes (Duarte, 1995; Borum, 1996; Cloern, 2001;

Andersen, et al., 2005). Harper (1992) therefore documents that cultural eutrophication can

have a significant negative effect upon the biodiversity of the ecosystem.

17

Figure 1. Diagram identifying the main stages of the eutrophication process (Triplepoint

Water Technologies, 2011).

3.2. Lake Deposits

Lake deposits have been used extensively for the reconstruction of past environments. In

recent years, however, there have been many advances and developments in the

techniques required to analyse and date lake deposits (Anderson, et al., 2007).

Palaeolimnologists now have the capability to generate high quality time-series data in

order to address important issues regarding cultural eutrophication (Battarbee, et al., 2005).

In comparison to other types of deposits, lake sediments provide continuous stratigraphic

records. This is because the sediments can accumulate over several epochs undisturbed by

erosion and weathering (Jenkin, et al., 1941; West, 1991; Anderson, et al., 2007). Lake

sediments can therefore provide a record of the environmental conditions in which the

sedimentation occurred and a record of the biological history.

3.3. Geochemistry

Geochemistry has been used as a valuable tool in palaeolimnology since the 1960s and plays

a central role in this field (Mackereth, 1966). Boyle (2001) argues that geochemical analysis

is extremely important in palaeolimnolgy in order to make conclusions about the

18

environment. However, the analysis of a geochemical record for phosphorous and nitrogen,

the root cause of eutrophication, is extremely difficult (Smol, 2002). This is because (i) the

preservation of phosphorous in sediments is determined by the sorption onto iron oxides,

and redox reactions can therefore affect this process (ii) anoxic conditions can causes the

post-depositional mobility of phosphorous, and phosphate can therefore be returned to the

lake water (Smol, 2002). Enstorm and Wright (1984), who also discusses the difficulties of

measuring past phosphorous concentrations, support this idea. Furthermore, Smol (2002)

reveals that the calculation of past nitrogen levels is fraught with error. It is for these

reasons that the phosphorus and nitrogen concentrations of the sediments at Quidenham

Mere will not be studied.

The concentration of sodium, however, can prove to be an alternative proxy for

eutrophication. A great body of literature has accumulated regarding this idea, despite

controversy over the mechanisms of this process. Provasoli (1969) documents that the

population of blue-green algae, a consequence of cultural eutrophication, increases with

enhanced sodium concentrations. Sharp (1971), who documented that the Twin City Lakes

(Minnesota) developed an extensive blue-green population following high inputs of sodium,

furthers this idea. Makarewicz and McKellar (1985) also acknowledged this relationship, and

Baybutt and Makarewicz (1981) documented that there was a significant correlation

between the increase in blue-green algae and the increase of the concentration of sodium.

There is therefore reason to believe that blue-green algae were present at Quidenham Mere

as it is one of the most common consequences of cultural eutrophication.

Possible explanations for this relationship include the necessary role of sodium to transform

nitrogen to ammonia in nitrogen fixing blue-green algae (Brownell and Nicholas, 1967). NAS

(1969) provides an additional explanation by documenting a strong relationship between

the release of phosphate from the lakebed and the total ionic content of the water. An

increase in the concentration of sodium in the water would therefore increase the

concentration of phosphate in the water, thus resulting in eutrophication. Furthermore,

Makarewicz and McKellar (1985) document that sodium can stimulate the phosphate

uptake in blue-green algae, and thus increase the growth rate. Therefore, an increased

concentration of sodium will result in an enlargement of the blue-green algae population,

and thus lead to eutrophic conditions.

19

Potassium may also be used as a proxy for eutrophication. Leentvaar (1980) documents the

possible role of potassium in the eutrophication process and argues that it is much more

complex than excessive phosphate and nitrogen inputs. This is supported by Wist et al.,

(2009) which argue that an increased concentration of potassium could cause a decline in

the population of blue–green algae (a direct cause of eutrophication). Furthermore,

Emerson and Lewis (1942), Allen (1952) and Kratz and Myers (1955) recorded the

intolerance of blue-green algae to increased potassium concentrations. It is therefore logical

that potassium can act as a recovery mechanism for eutrophication and that an increase in

the concentration of potassium can indicate the final stages of eutrophication.

3.4. Micropaleontology

Micropaleontology is a branch of science concerned with the study of microfossils in order

to reconstruct paleoenvironments (Martin, 2000). A particular fossil commonly used in

micropaleontology are the freshwater molluscs. Freshwater molluscs have an extraordinary

fossil record dating back to the Cambrian Period, and include two classes: Gastropod and

Bivalvia (Sturm, 2006; Dillon Jr., 2000).

3.4.1 Gastropods.

The Gastropoda class is the largest of the molluscan classes containing approximately 150,

000 species (Aktipis, et al., 2008). Gastropods are classified by having a dextral, helically

coiled aragonite shell (Ponder and Lindberg, 2008). They are unique among the classes of

molluscs as they display torsion of the body (Figure 2). (Karleskint, et al., 2009).

Furthermore, the class of gastropoda can be divided into two taxa: Pulmonata and

Prosobrachia (Boss, 1978). Snails of the subclass Prosobranchia are gill breathing, while

snails of the subclass Pulmonata are non-gill breathing. Snails of the latter carry an air

bubble nderneath their shell in order to respire (Sturm, 2006).

20

3.4.2. Bivalves

The Bivalvia class, however, is the second largest of the molluscan classes (Giribet, 2008).

Bivalves consist of a compressed body enclosed by two aragonite and/or calcite valves

(Figure 3). These valves are hinged together dorsally by adductor muscles and by

interlocking teeth (Tunnel, et al., 2010). The shape of the valve however varies between

species and can be either equilateral, inequivalve, or a combination of the both.

Figure 3. Diagram of a generalized bivalve, with the main features labelled. Note that when

the adductor muscles relax the hinge ligaments expands and the shell opens (Little, 2008)

Figure 2. Diagram of a generalized

gastropod. The operculum is a corneous

plate that molluscs secrete over their shell

opening to survive predators and periods of

drought (Ghesquiere, 2011).

21

Freshwater molluscs have gained scientific attention since the 17th century. Merrett (1666),

listed the plants and animals of The British Isles and recorded six species of mollusc. The

study of molluscs remained a lively topic throughout this century and Lister (1678) recorded

the geographical distribution of molluscs within the British Isles. Jeffreys (1982), who

synthesized all existing literature regarding the classification and distribution of molluscs,

significantly advanced this research area. However, Merrett (1666), Lister (1678) and

Jeffreys (1982) have been strongly criticised as being too descriptive (Ložek, 1986). In the

early 1950s, there was a growing sense that the existing paradigm of molluscan study was

unscientific and lacked purpose. A more theoretical approach subsequently occurred,

emphasizing the quantification of data. Studies therefore grow in complexity with the

advance of technology (Miller and Tevesz, 2001). A highlight of this time was the work of

Sparks (1961) which documented the great biostratigraphical significance of molluscs. Talyor

(1960), Ložek (1986) and Keen (1990) also recognised the paleoenvironmental advantages

of the study of molluscs.

Molluscs are an ideal proxy to study the effects of cultural eutrophication. A great body of

literature has accumulated documenting that freshwater molluscs can be used as an

indicator of eutrophic conditions (e.g. Arter, 1989; Nakamura and Kerciku, 2000; Carlsson

2001; Jou and Liao, 2006; Timm, et al. 2006). Furthermore, Dussart (1979) documents that

the abundance of some mollusc species is positively correlated to the concentration of

potassium and negatively correlated to the concentration of sodium. Molluscs are also

advantageous in the field of palaeoecology as they are extremely numerous (Bignot, 1982).

Molluscs inhibit a wide range of sedimentary deposits such as windblown (Miller, et al.,

1994), fissures (Miller, et al., 1994b) and fen peat deposits (Miller and Thompson, 1987). An

additional advantage is that they exhibit wonderful patterns of variation between and

within species. For example, the shape of the operculum and the pattern of the suture can

vary between species. As a result, molluscs can be used for stratigraphic zonation and to

reconstruct former habitat and climatic conditions (Miller, et al., 1985). The most important

advantage, however, is that molluscs are preserved in situ in a long and complete fossil

record. This allows an in depth analysis over a many epochs.

22

3.5. Summary

Scientific investigations focusing upon cultural eutrophication have been limited in recent

years. This has resulted in a poor historical record of this phenomenon (Cheng, et. al., 2007).

Furthermore, there is an uncertainty regarding the extent to which anthropogenic activities

influence natural eutrophication (Cheng, et. al., 2007). There is therefore considerable

scope for more palaeoecological and paleolimnological studies regarding cultural

eutrophication. In order to reduce this phenomenon in the future, greater studies into the

past need to be undertaken. A fuller understanding of the topic will therefore be achieved.

Consequently, anthropogenic activities, that promote cultural eutrophication, will be able to

be successfully managed.

In order to determine the process of cultural eutrophication at Quidenham Mere, the

potassium and sodium content was measured (Grigorovich, et al., 2005). The organic

material content was also measured due to its direct relationship with this phenomenon

(Nixon, 1995). Ongley (2006) and Ortega, et al., (2006), who reveal that the organic matter

content of the sediment increases during eutrophication, support this idea. Rabalais (2010)

further supports this idea by documenting Grigorovich that the increase of organic matter

during eutrophication is due to soil erosion, natural weathering, or human activity. This

multi-proxy method is ideal as it can abolish misleading information provided by single-

proxy studies (Engstrom and Wright, 1984; Boyle, 2001: Birks and Birks, 2006). An increase

in the concentration of sodium is used as an indication to the start of the phenomenon, and

a decrease in the concentration of potassium is used as an indication to the restoration of

the lake. The population of molluscs in the sediment at Quidenham Mere was also studied

in order to evaluate the effects of anthropogenic activities. Molluscs were chosen as they

are susceptible to environmental change, and can therefore produce informative results.

This literature will provide a greater insight into the process of cultural eutrophication, as it

is clear that there are gaps in the knowledge in this field. It will help further the current

state of knowledge by highlighting what effect anthropogenic activities have upon the

population of molluscs at Quidenham Mere. This literature will also aid the development in

this research field.

23

Chapter 4: The study area

4.1. Site location and description

Quidenham Mere is a small shallow lake

located on the eastern edge of Breckland

in south Norfolk, UK (52°30’ N, 1°0’E;

National Grid Reference: TM 040875).

The area is composed of chalky boulder

clay deposited by the Anglian glaciations,

overlying chalk bedrock (Perrin, et al.,

1979) (Figure 4). The lake sediments are

calcareous marls (approximately 12 m),

with abundant shell and Characeae

remains (Cheng, et al., 2007). A thick

layer of dark peat (>2 m) overlies the

calcareous marls.

Quidenham Mere is extraordinary among East

Anglian Meres as it has an inflowing stream,

which drains from approximately 5km to the

south and east (Lewis, et al., 1991). A drainage

network has therefore been added to the fen

woods of the east and north of the Mere (Figure).

The present lake is roughly oval, with a short axis

of 200 m and long axis of about 300m (Lewis, et

al., 1991). There is however evidence that the lake

was greater in size at the onset of the Holocene

epoch (Bennett, et al., 1991).

Figure 4. A geological map of East

Anglia, with the location of Quidenham

Mere indicated (Peglar, 1993).

Figure 5. The local topography of

Quidenham Mere and the local

landmarks (Peglar, 1993).

24

4.2. Site Selection

Quidenham Mere was chosen as the study site for numerous reasons. Previous work at

Quidenham Mere, for example, has only focused upon the fossil pollen and charcoal content

of the sediments. There has been no work, however, focussing upon the nutrient

concentration of the sediments. This is an important variable to investigate in order to

further our knowledge of the eutrophication event at Quidenham Mere. Furthermore,

Cheng, et al., (2007) lacks detail of which species of mollusc where effected by the medieval

eutrophication event. Adding to this, there has been no work focusing upon the top 200m of

the sediment sequence. This literature will therefore give a greater insight into the cultural

eutrophication process and provide a basis for further study of the recent eutrophication

event at Quidenham Mere.

4.3. Limitations of study site

The main limitation of the study site is that the site cannot be accurately dated. The

sediments of Quidenham Mere are highly calcareous and are therefore unsuitable for

radiocarbon dating (Peglar, 1993). This is because ‘hard-water’ errors are likely to occur. The

sediments of Quidenham Mere are also unsuitable for accelerator mass spectrometry (AMS)

as not enough material can be extracted. However, this problem can be overcome by

comparing the sediment composition of Quidenham Mere with the sediment composition

of Peglar (1993) (Chapter 5 provides a full explanation for this criterion).

25

Chapter 5: Methodology

5.1. Coring procedure

Members of The University of Leeds Geography Department, following the standard

procedure of Wright (1967), extracted the Quidenham Mere Core. 8.3 m of core was

recovered using a 5 cm diameter Livingstone corer. However, the exact location of the

coring site at Quidenham Mere is unknown.

5.2. Sediment lithology

Valuable information about former climates and environments can be derived from the

nature of Late Quaternary sediments. For example, the biological, chemical and physical

properties of the sediment can provide information on the environment of deposition.

Furthermore, stratigraphic relationships can provide information on depositional changes

through time, while sediment accumulation rates can provide a proxy record of climate

change (Bell and Walker, 2005). A sediment description was therefore performed prior to

sediment sampling to address all three aims of this literature. Lowe and Walker (1997) agree

that sediment lithology is an important topic to investigate.

The sediment lithology of the core was analysed using the system of Troels-Smith (1955).

The Troels-Smith system was chosen, as other systems for describing organic sediments are

genetic in their character (West, 1977; Birks and Birks, 1980). Furthermore, it recognizes

that sediments are frequently mixtures of elements, thus making it a logical and versatile

approach (Birks and Birks, 1980). The sediment lithology of the core was therefore

described on a five-point scale (0, 1, 2, 3, 4, +) by:

1. The physical properties (colour, dryness, stratification etc.)

2. The composition of the core (silt, marl, lake mud etc.)

(Birks and Birks, 1980).

26

5.3. Sediment composition

Gravimetric analysis’ are of considerable importance in palaeolimnology as they are able to

provide an index of the biological productivity in former lake basins, (Lowe and Walker,

1997). The organic matter content and carbonate content of the core was measured to

calculate the age of the core (section 5.4). The organic content was also measured to

determine the timing of eutrophication at Quidenham Mere. By analysing the organic

matter content and carbonate content of the core, aim number one and two will be

addressed.

Loss-on-ignition was performed at 450°C and 950°C to calculate these variables following

the standard procedure of Hesse (1971). A full description of this method is provided in

Appendix 10.1.1. This method was chosen as Boyle (2001) documents that it is simple and

reliable method to perform. Samples were taken every 5 centimetres, to allow an accurate

comparison with Peglar (1993). The temperature of 450°C was chosen as Ball (1964)

documents that this is an appropriate temperature for the oxidation of organic matter.

Furthermore, Jordan, et al., (2002) documents that this is a sufficient temperature for this

aim. The temperature of 950°C was chosen as Heiri, et al., (2001) documents that this is an

appropriate temperature for carbon dioxide to be evolved from carbonate. Furthermore,

Dean (1974) shows a strong correlation between LOI at 950°C and the carbonate content in

lake sediments. A consistency in the LOI method was implemented in relation to the ignition

temperatures, exposure times and sample size, as recommended by Heiri, et al., (2002).

5.4. Chronology

The chronology of the sediments at Quidenham Mere is an important subject to identify,

and a technique that is frequently used in palaeoenvironmental research. It is particularly

important in this study, as it can help explain why Quidenham Mere experienced

eutrophication. For example, it is possible to determine, by knowing when the phenomenon

occurred, whether it was human induced or whether it was a natural occurrence. This

method therefore corresponds with aim number one, but can also add weight to the other

aims of this literature.

27

The sediments at Quidenham Mere are unsuitable for traditional dating methods. However,

Peglar (1993) provides a tentative chronology for the sediments of Quidenham Mere. This

work is based on the literature of Bennett (1983, 1986, 1988) which provides radiocarbon

dates for similar sites close to Quidenham. It is therefore possible, by comparing the organic

and carbonate peaks on the sediment composition diagram of Peglar (1993) and QUID1, to

calculate approximate age boundaries for QUID1. The results of the dating are shown in

section 6.1.

5.5. Geochemistry

Geochemical analysis of lake sediments has been a crucial technique in paleolimnology since

the work of Mackereth (1966). It plays a valuable role in determining a link between

sediment composition and the environment (Boyle, 2001).

A great body of literature has accumulated documenting that the concentration of

potassium and sodium in sediments can be used to indicate eutrophication (Leentvaar,

1980; Livingstone and Boykin, 1962; NAS, 1969). The concentration of potassium and

sodium of the sediment was therefore recorded to address aims one and two. The

concentration of potassium and sodium were measured using flame atomic absorption

spectrometry (FAAS). Boyle (2001) documents that FAAS is an ideal instrument for

measuring alkali metals as it is simple and produces robust results. Electrothermal atomic

absorption spectrometry (EAAS) was not chosen due to the matrix interference effects of

this apparatus (Boyle, 2001).

The pH of the sediment was measured in order to decide an appropriate method for cation

extraction. If the sample had a pH > 5, ammonium acetate would have been used for the

cation extraction (Gillman, 1979). It the sample had a pH < 5, ammonium chloride would

have been used for cation extraction (Narin, et al., 2000). The pH was recorded at 2 cm

intervals throughout the core using the electrometric method. The samples were then

analysed using FAAS to answer aim two. A full description of this method is provided in

Appendix 10.1.2. This is a sufficient method for interfering past nutrient levels and provides

valuable information on past processes (Boyle, 2001).

28

5.6. Magnetic susceptibility

The concentration of magnetic mineral can be reliably recorded by measuring the magnetic

susceptibility of sediments (Nowaczyk, 2001). This technique is an important

palaeoenvironmental indicator and has grown in popularity over the last two decades

(Mackereth, 1966; Bengtsson and Enell, 1986; Nowaczyk, 2001). Variations in the magnetic

properties of sediments have been used to make conclusions about a number of

environmental process including sediment flux and erosion in lake catchments (Dearing, et

al., 1981; Hirons and Thompson, 1986; Lowe and Walker, 1997). This method was therefore

performed to address aim number two.

For this investigation, the ‘whole core logging technique’ was used, as the recovery rate

from the coring procedure was very good. A MS2C sensor was used, as Dearing (1999)

documents that it is the appropriate apparatus for this study (Figure 6). Furthermore, this

method is a non-destructive technique and simple to perform. The first step of the

procedure was to measure the calibration sample provided by the manufacturer. The

calibration sample is a ferromagnetic material with a high magnetic susceptibility and can

confirm the long-term calibration of the MS2C meter (Dearing, 1999). The susceptibility

meter was subsequently correlated to zero against the magnetic background (Nowaczyk,

2001). Following this step, the whole core was placed into the loop sensor and recordings

were taken every 2 cm. This stratified sampling technique was designed in order to produce

a large and robust data set.

Figure 6. Diagram of the Bartington

system designed to measure the magnetic

susceptibility of sediments (Nowaczyk,

2001). The loop sensor should be a similar

size to the core in order to produce

accurate results.

29

5.7. Mollusc Analysis

Mollusc shells are one of the most common fossil remains in terrestrial Quaternary

sediments and are therefore useful palaeoenvironmental indicators (Lowe and Walker,

1997). An analysis of the mollusc shells was undertaken in order to address aim number

three. The interval and thickness of each sample depends on a variety of factors including

the concentration of molluscs in the sediment and the frequency of the sampling method.

Due to the variation in concentration of molluscs throughout the core, there are no

documented guidelines for the weight or volume of sediment required. A pilot study was

therefore performed to produce a species acquisition curve (Henderson, 1990). A small

subsample of sediment was taken and the number of species present was recorded. The

sample size was then increased in small additions until the plot for number of species

reached asymptote (Griffiths and Holmes, 2000). It is then possible to estimate the mass of

sediment required to achieve full species representation. The results of this investigation

are shown in figure 7.

Figure 7: A mollusc acquisition curve for the QUID1 core. In order to produce an accurate

acquisition curve, 10 samples were taken from the core at each weight, and the average was

recorded. The plot reaches asymptote at 12 individuals per sample weight. It is therefore

clear that a sample of 20 g should be extracted to achieve a full species representation.

30

The molluscan remains were extracted under laboratory conditions following the standard

procedure of De Deckker and Forester (1982). Ložek (1986) and Griffiths (1995) have proved

this method successful. Furthermore, Sparks (1964) documents the high level of accuracy of

this method. Sediment samples were taken every ten centimetres along the core to provide

an extensive data set. All samples were taken from the middle of the core where

disturbance is minimal. Furthermore, the surface of the sediment was carefully removed in

order to avoid contamination (Birks and Birks, 2004). The identification of the molluscan

remains was based on the work of Macan (1977) and Kerney (1999). A full description of this

method is provided in Appendix 10.1.3/

5.8. Statistics

Statistical analyses were performed upon the data, using Minitab 1.6, to prove that the

conclusions of this literature are statistically significant. Anderson-Darling normality tests

were initially performed to determine if the data sets are normally distributed (Dytham,

2011). Following this, Spearman’s rho tests were performed as the data sets, as indicated by

the Anderson-Darling tests, were not normally distributed (section 6.4). Furthermore, the

control variables and the response variables are continuous variables.

In order to address aim one, a Spearman’s rho test was performed using the potassium and

sodium data. In order to address aim two, a Spearman’s rho test was performed using the

silica and magnetic susceptibility data. This was undertaken to determine if the magnetic

susceptibility results can be used to indicate periods of soil erosion, or if the results are

controlled by the input of silica. To address the third aim of this literature, a Spearman’s rho

test was performed upon the mollusc data and the organic, potassium and sodium data. The

aim of this test was to identify if the population of molluscs at Quidenham Mere changed in

response to the episodes of cultural eutrophication.

Quantitative zonation was also performed upon the mollusc data to prove that there is a

significant statistical difference between groups of molluscs. The quantitative zonation was

performed using Psimpoll software and the optimal splitting by information content’ option

was chosen. This is method was chosen because it is robust and reliable (Lawson, 2011).

31

5.9. Limitations of methods

Several limitations regarding the Troels-Smith method, the mollusc extraction and

identification and the magnetic susceptibility method have been identified. The Troels-

Smith sediment description system can sometimes be problematic for the reason that it

relies on descriptive results (Birks and Birks, 1980). The method can therefore lead to

different interpretation by different researchers. However, if the process if followed

accurately, differing results can be kept minimal.

The mollusc extraction method can prove to be difficult due to the use of hydrogen

peroxide. Even though hydrogen peroxide is frequently used for non-marine Mollusca

analysis, several pieces of literature argue that hydrogen peroxide can destroy fragile shells

(Sohn, 1961; Hodgkinson, 1991; Slipper, 1996). Extreme care was therefore taken to ensure

that the mollusc shells were not damaged.

Additionally, the identification of molluscs can be complicated. For example, many mollusc

species vary in their morphology and markings from juvenile to adult stage and their

colouring and fine sculpture due to local environmental conditions (Lowe and Walker, 1997)

Furthermore, fossil remains can be damaged during sediment compaction or by the washing

down of the sediment (Sparks, 1964). Large bivalves for example, are rarely recovered in an

identifiable condition from compacted sediment as they shatter easily (Sparks, 1964). An

additional point to note is the over representation of Bithynia sp. This is because this genus

is more readily preserved in comparison to other genuses due to its think operculum (Figure

2) (Sparks, 1964).

The magnetic susceptibility method can also be difficult to perform accurately. This is

because the sensors are affected by electromagnetic fields, the presence of magnetic

materials and changes in temperature (Dearing, 1999). In order to produce accurate results,

the system of Dearing (1999) was followed precisely.

32

5.10. Ethical Issues

Environmental issues and health and safety issues have been acknowledged in the design of

the methods for this study (Appendix 10.6). For example, laboratory wastes were placed in

waste bags for incineration and all sharp instruments were placed in sharp bins after use.

Furthermore, the findings of the literature are not harmful to others and cannot be used in

a negative way. The findings shall instead add to the literature of paleoenvironments in

Norfolk during the Holocene epoch.

5.11. Summary

The methods have also been designed to address the aims and objectives of this literature.

For example, sections 5.3 – 5.5 have been designed to address aim number one, section 5.6

to address aim number two and section 5.7 to address aim number three. Section 5.2 and

the statistical analysis have been designed, however, to address the three aims of the

literature.

33

Chapter 6: Results

6.1. Sediment Lithology

The sediment lithology of the core has been determined to explain the three aims of this

literature. The results of this analysis are displayed in Figure 8 and 9, and further described

in Appendix 10.2.2. The bottom of core QUID1 is composed largely of calcium carbonate.

Particulate testarum molluscorum become present at 802 cm and remains throughout the

core. The calcareous marl varies in stratification from values 1 – 3 and undergoes a rapid

transition into peat at 360 cm, which remains until 125 cm. The base of the peat is very dark

brown/black and is composed of Sphagnum leaves. In the middle part of this section, the

peat becomes lighter, coarser and contains fragments of herbaceous plants and wood

segments such as Betula. The peat continues becoming lighter above this section and

herbaceous plants and wood segments dominate. The peat then gradually changes to a dark

brown herbaceous peat at approximately 161 cm.

Aim 1: Approximately, when did cultural eutrophication happen at Quidenham Mere?

6.2. Sediment composition

There is a similarity between the trends of the organic and carbonate content throughout

the two cores, however the major features occur at different depths. For example, the

organic content of the QUID1 core first peaks at 770 cm to approximately 34%, while the

organic content of Peglar’s (1993) core peaks at 790cm to approximately 38%. Furthermore,

the carbonate content of the QUID1 core declines to 680 cm, while Peglar (1993) shows that

it declines to 720 cm. Peglar (1993) also shows a slight decline in the organic content at 510

cm, followed by a rise in the carbonate content. This study also found this trend, however

the organic content of QUID1 declines at 420 cm. It is therefore clear that QUID1 differs to

Peglar’s (1993) sediment composition by 40-90 cm.

34

Key to lithology

Figure 8. A comparison between Peglar’s (1993) sediment composition diagram (434 – 1240

cm) and the QUID1 sediment composition diagram (125-830 cm). The key follows the

classification system of Troels-Smith (1955). The coloured lines indicate where the organic

and carbonate component correspond. Red indicates a comparison between the organic

variables and blue indicates a comparison between the carbonate variables. The silica

content is the first variable on the x-axis to allow a clear comparison between the organic

and carbonate variables.

35

Figure 9. Sediment lithology, sediment composition and tentative chronology at

Quidenham Mere. See Key from figure 8 for the sediment lithology.

36

6.3. Geochemical analysis

Figure 10. Geochemical analysis of Quidenham Mere, focusing upon the concentrations

of potassium and sodium.

Two peaks are prominent in the concentration of both potassium and sodium. From the

base of QUID1, the concentration of potassium is approximately 17 mg/kg. The

concentration of potassium peaks at 745 cm (approximately 80 mg/kg) before gradually

decline to approximately 15 mg/kg. This variable then fluctuates greatly between 3 and

21 mg/kg, before rapidly rising to approximately 160 mg/kg. Following a rapid decline in

the concentration of potassium, a peak is prominent at 345 cm (approximately 160

mg/kg). The concentration of potassium then quickly declines and fluctuates between 10

and 20 mg/kg between 325 cm – 125 cm.

The concentration of sodium throughout QUID1 is greater than that of potassium, yet

follows a similar pattern. From the base of QUID1, the concentration of sodium is

approximately 131 mg/kg until it gradually peaks at 765 cm to approximately 200 mg/kg.

This variable then rapidly declines and fluctuates greatly between 50 mg/kg and 140

mg/kg until 455 cm. At 455 cm, the concentration of sodium sharply rises to 310 mg/kg,

before declining rapidly to 150 mg/kg. This is followed by another rapid increase at 395

cm to 342 mg/kg. Following this rise, the concentration of sodium rapidly declines and

greatly fluctuates between 60 and 133 mg/kg throughout the rest of the core.

0

50

100

150

200

250

300

350

400

12

5

15

5

18

5

21

5

24

5

27

5

30

5

33

5

36

5

39

5

42

5

45

5

48

5

51

5

54

5

57

5

60

5

63

5

66

5

69

5

72

5

75

5

78

5

81

5

Co

nce

ntr

atio

n (

mg/

kg)

Depth (cm)

Distribution in depth of the concentration of sodium and potassium in the sediments of Quidenham Mere.

Potassium

Sodium

37

6.4. Non-parametric analysis (1)

Table 1. A summary of statistical analysis performed to address aim number one. For the

Anderson-darling test, the data is normally distributed if p > 0.05. For the Spearman’s

rho test, the two variables are statistically correlated, to a 95% confidence level, if p <

0.05

The result of the Spearman’s rho test for the sodium and potassium variable shows that

p = 0.758. 0.758 > 0.05, indicating that there is no statistical significant correlation

between these two variables. Ho number one is therefore accepted. This finding was

expected as an increase in the concentration of sodium indicates the onset of the

eutrophication process, while an increase in the concentration of potassium indicates

the onset of the restoration process. The concentration of sodium and potassium can

therefore be used to identify eutrophication at Quidenham Mere.

38

Aim 2: Why did the eutrophication events at Quidenham Mere occur?

6.5. Magnetic susceptibility

Figure 11. The magnetic susceptible elements in the sediments of Quidenham Mere.

The magnetic susceptibility results are displayed in Figure 11. The results reveal a

general increase in magnetic susceptible elements from 830 cm to zero cm. Figure 11

also shows that the core is rich in diamagnetic substances due to the negative values on

the y-axis (Dearing, 1999). One of the diamagnetic substances in the core may be

carbonate. A reason for this suggestion is that the sediment analysis (Figure 8) shows

that QUID1, especially in the lower parts, is highly composed of carbonate. However,

water may also be present in the core, leading to the negative values. On closer

analysis, the results reveal a relatively steady input of magnetic susceptible elements

from 830 cm to 690 cm, with minor fluctuations. Following this, the rate of input rapidly

increases between 690 and 530 cm. The input of magnetic susceptible elements then

becomes relatively steady, with minor fluctuations, between 530 cm and 0 cm.

-16

-14

-12

-10

-8

-6

-4

-2

0

12

5

15

1

17

7

20

3

22

9

25

5

28

1

30

7

33

3

35

9

38

5

41

1

43

7

46

3

48

9

51

5

54

1

56

7

59

3

61

9

64

5

67

1

69

7

72

3

74

9

77

5

80

1

82

7

Mag

ne

tic

susc

ep

tib

ility

Depth (cm)

Distribution in depth of the magnetic susceptibleelements at Quidenham Mere.

39

6.6. Non-parametric analysis (2)

A Spearman’s rho test was performed using the silica and magnetic susceptibility data.

The test shows that r = 0.356, which indicates a weak positive correlation between the

two variables. The results also reveal that p = 0.002. 0.002 < 0.05, which indicates that

there is a statistical significant correlation to a 95% confidence level. H1 number two is

therefore accepted.

Aim 3: To examine the abundance of molluscs at Quidenham mere, in order to

determine how the molluscs responded to cultural eutrophication.

6.7. Mollusc Analysis

At least five species of molluscs are present in the sediment of Quidenham Mere since

the medieval period. These are Bithynia tentaculata, Gyraulus laevis, Lymnaea peregra,

Valvata macrostoma and Valvata piscinalis (Figure 12 - 17). Other genuses were

identified in the sediment, but could not be identified to species level due to damage of

the shell. These are Lymnaeidae sp., Gyraulus sp. and Pisidium sp.

Figure 12. Bithynia tentaculata: Belonging to the

gastropod class, this is a common prosobranch

found in slow-moving, well-oxygenated lakes

(Kerney, 1999). It can survive well in lakes with

high concentrations of calcium and potassium

(Jokinen, 1992).

40

Figure 13. Gyraulus laevis: Belonging to the

gastropod class, these pulmonates are

extremely common in clean, quite water

(Alder, 1838; Kerney, 1999).

Figure 14. Lymnaea peregra: Belonging to

the gastropod class, these pulmonates are

found in a variety of environments, such as

rivers, canals and ephemeral ponds (Kerney,

1999). There is controversy, however, as to

whether these snails can survive in

eutrophic conditions.

Figure 15. Valvata macrostoma: Belonging

to the gastropod class, these prosobranchs

are found in slow moving, well-vegetated,

calcium rich waters (Kerney, 1999). They

are, however, extremely rare in The British

Isles.

41

Figure 16. Valvata piscinalis: Belonging to the

gastropod class, this is a common prosobranch

found in muddy or silty substrates (Kerney,

(1999). Furthermore, this snail is tolerant of

oligotrophic zones and varying carbonate

concentrations (Fretter and Graham, 1978;

Grigorovich, et al., 2005).

Figure 17. Pisidium sp.: Belonging to the

bivalve class, this species is found in a variety

of environments (Kerney, 1999). The diagram

shows a generalized Pisidium species.

The preferred way of displaying mollusc data is by calculating influx rates, using the

following formula: ia = ca/d where ia = influx rate, ca = concentration of molluscs and d =

sediment deposition rate. However, because the sediment deposition rate for

Quidenham Mere is unknown, concentration values have been reported. Proportion

data has not been included in this literature, as this data is affected by the total sum.

Proportion data does not therefore accurately represent the sample.

42

6.8. Quantitative Zonation

Quantitative zonation shows that the mollusc concentration data can be divided into

four statistical significant zones for the mollusc concentration data (Figure 18). These are

from the base upwards:

Zone Q-1: Zone Q-1 is characterised by a low abundance of molluscs. Only Gyraulus sp.

and Pisidium sp. are present in this zone.

Zone Q-2: Bithynia tentaculata is the prominent mollusc species in zone Q-2. The

concentration of Bithynia tentaculata at the base of zone Q-2 is relatively high.

Throughout the zone, the concentration of this mollusc increases, before declining

towards the boundary of zone Q-3. The concentration of Gyraulus laevis, Valvata

macrostoma and Valvata piscinalis increases throughout the zone, while the

concentration of Pisidium sp. remains relatively constant. Lymnaea peregra and

Gyraulus sp. however are relatively scarce within this zone.

Zone Q-3: At the base of the zone, the concentration of molluscs in the sediment is

relatively high. Bithynia tentaculata, Valvata piscinalis, Valvata macrostoma, Lymnaea

peregra, Lymnaea sp. and Gyraulus laevis remain high until 745 cm before declining.

Following this decline, the concentrations of these species remains roughly constant,

with minor fluctuations, throughout the rest of the core. It is important to note that

Gyraulus laevis is not present in every sample throughout zone Q-3. The concentration

of Gyraulus sp. shows a general decline until 635 cm, where the concentration of this

variable is zero. Following this decline, this variable fluctuates around 0.2 individuals per

gram for the rest of the zone. The concentration of Pisidium sp., however, far exceeds

the concentrations of the other molluscs in this zone. Pisidium sp. fluctuates around 0.3

individuals per gram throughout this zone, showing no clear trend.

43

Zone Q-4: Until 395 cm, the concentration of molluscs in the sediment is relatively

steady. At 395 cm, the concentration rapidly increases until a depth of 320 cm. Lymnaea

peregra and Lymnaea sp. show the largest increase, while Pisidium sp. shows the

smallest increase. The concentration of Bithynia tentaculata, Gyraulus sp., Valvata

piscinalis and Lymnaea sp. fluctuates around 0.2 individuals per gram throughout the

rest of the core. Lymnaea peregra, Valvata macrostoma and Pisidium sp. however,

remain relatively constant until 205 cm where the concentrations increase. Following

this rise, the concentrations of these species remains steady, with minor fluctuations

until the top of the core. After the rise in the concentration of Gyraulus laevis between

390 and 320 cm, the concentration of this species remains approximately 0.2 individuals

per gram until the upper boundary of Zone Q-4. This species, however, is absent from

the sample of 275 cm.

44

Figure 18. The concentrations of the molluscs at Quidenham Mere, divided by

quantitative zonation. The graph shows that the concentrations of the molluscs increase

between the first (800 – 685) and second (455 -325) episode of cultural eutrophication.

6.9. Non-parametric analysis (3)

The results of the Spearman’s rho test show that there is a significant mild positive

correlation between the number of molluscs in the sediment and the organic matter

content. H1 number three is therefore accepted. When analysing the individual species

however, H1 number three is accepted for all species bar Gyraulus laevis and Lymnaea

peregra. The results of the Spearman’s rho test show that there is a significant weak

positive correlation between the number of molluscs in the sediment and the

concentration of potassium. H1 number four is therefore accepted. When analysing the

individual species however, H1 number four is accepted for all species bar Gyraulus laevis

and Lymnaea peregra. The results of the Spearman’s rho test show that there is not a

45

significant correlation between the number of molluscs in the sediment and the

concentration of sodium. Ho number five is therefore accepted. The results also reveal

that that there is no correlation between the number of the individual species of mollusc

in the sediment and the concentration of sodium. Ho number five is therefore accepted

for all species.

6.10. Summary

The results have been discussed in way to support the aims of the literature and the

structure of this section has been designed to reflect this. For example, sections 6.2 – 6.3

have been designed to address aim number one, sections 6.4 - 6.6 have been designed

to address aim number two and sections 6.7 – 6.9 have been designed to address aim

number three. The objectives of this literature have also been achieved by the

documented results.

.

46

Variable Bithynia

tentaculata

Gyraulus laevis

Gyraulus sp.

Lymnaea peregra

Lymnaea sp.

Valvata piscinalis

Valvata macrostoma

Pisidium sp.

Total

Anderson-

darling

<0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005

Organic

matter

content

Mild positive

correlation (R

= 0.507, P =

0.000)

Not correlated (P

= 0325)

Mild positive

correlation (R

= 0.478, P =

0.000)

Not correlated (P

= 0.473

Mild positive

correlation (R

= 0.432, P =

0.000)

Mild positive

correlation (R

= 0.417, P =

0.000)

Mild positive

correlation (R =

0.490, P = 0.000)

Weak

positive

correlation

(R =0.315, P

= 0.007)

Mild positive

correlation (R

= 0.487, P=

0.000)

Potassium Mild positive

correlation (R

= 0.447, P =

0.000)

Not correlated (P = 0.119)

Weak positive

correlation (R

= 0.315, P =

0.008)

Not correlated

(P = 0.499)

Weak positive

correlation (R

= 0.292, P =

0.014)

Weak positive

correlation (R

= 0.281, P =

0.018)

Mild positive

correlation (R =

0.538, P = 0.000)

Mild

correlated (R

= 0.479, P =

0.000)

Weak positive

correlated (R

= 0.343, P =

0.003)

Sodium Not correlated

(P = 0.338)

Not correlated (P

= 0.619)

Not correlated

(P = 0.836)

Not correlated (P

= 0.415)

Not correlated

(P = 0.450)

Not correlated

(P = 0.219)

Not correlated (P

= 0.805)

Not

correlated (P

= 0.840)

Not correlated

(P = 0.825)

Table 2. A summary of the statistical analyses performed on the mollusc data and environmental data. For the Anderson-darling test, the data is normally distributed if p > 0.05. For the Spearman’s rho test, the two variables are statistically correlated if p < 0.05.

47

Chapter 7: Discussion

7.1. When did the eutrophication events happen at Quidenham Mere?

The results reveal that two episodes of eutrophication occurred at Quidenham Mere since

the medieval period. The first episode of eutrophication occurred at approximately 800 –

685 cm (medieval/ post-medieval period). This idea coincides with the work of Cheng, et al.,

(2007) who also documented this event. The second episode of eutrophication occurred at

approximately 455 – 325 cm (the last 200 years). No previous literature has focused upon

the 450 – 0 cm section of the profile before, therefore the latter is a new finding.

7.1.1. The onset of the eutrophication process

There is evidence to suggest that the onset of eutrophication at Quidenham Mere occurred

at 800 cm and at 455 cm. The reason for this statement is that the concentration of sodium

increases at these depths. Sharp (1969), Provasoli (1971), Baybutt and Makarewicz (1981)

and Makarewicz and McKellar (1985) support this idea. Furthermore, the organic matter

content increases after the increased concentration of sodium (Figure 8). These depths have

therefore been used as the onset of cultural eutrophication at Quidenham Mere in this

literature. Ongley (2006), Ortega, et al., (2006) and Rabalais (2010) support this idea.

7.1.2. The onset of the restoration process

There is evidence to suggest that the onset of the restoration process at Quidenham Mere

occurred at 685 cm and at 325 cm. The reason for this statement is that the concentration

of potassium declines at these depths. Leentvaar (1980), who documents that the

concentration of potassium can be used as a proxy of eutrophication, supports this idea.

Emerson and Lewis (1942), Allen (1952), Kratz and Myers (1955) and Wist, et al., (2009),

who document that an increased concentration of potassium indicates a change of trophic

levels, supports this idea. Furthermore, the organic matter content is low after the

decreased concentration of potassium (Figure 8). These depths have therefore been used as

48

the onset of cultural eutrophication at Quidenham Mere in this literature. Ongley (2006),

Ortega, et al., (2006) and Rabalais (2010) support this idea.

7.1.3. Summary

Previous paleolimnological studies document that the organic matter content, the

concentration of potassium and the concentration of sodium can be used to identify

eutrophication. This study agrees this knowledge. This is because there is not a significant

statistical correlation between the potassium concentration and the sodium concentration.

Furthermore, the organic matter content increases following a rise in the concentration of

sodium. Therefore, there is sufficient evidence to suggest that cultural eutrophication

occurred between 800 – 685 cm (medieval/post-medieval) and between 455 – 325 cm (the

last two hundred year). These depths and dates have therefore been used throughout the

rest of the study.

49

7.2. Possible causes of cultural eutrophication at Quidenham Mere

Both episodes of eutrophication will be discussed to gain a fuller understanding of the

impacts of anthropogenic activities at Quidenham Mere.

7.2.1. Possible causes of the medieval/ post-medieval eutrophication event

Cheng, et al., (2007) documents that hemp retting caused Quidenham Mere to become

eutrophic during the medieval/ post-medieval (M/P-M) period. This relationship occurs

because the process of hemp retting causes the organic matter content and nutrient

concentration of the lake to increase. This is because hemp retting involves depositing

bundles of mature Cannabis sativa stems (a member of the Cannabaceae family) into a lake.

Microorganisms in the lake then consume the cellular tissue of the hemp, and the fibre of

the stem becomes available to make sails, ropes, clothes and fishing nets. The results of this

study provide evidence to support this idea. A similar view of Cheng, et al., (2007) is shared

by Yang (2010) who documents that hemp retting caused Quidenham Mere to become

contaminated. Furthermore, Peglar (1993) reports that the percentage of Cannabaceae

increased during the M/P-M period, thus suggesting hemp retting (Figure 19). Cox, et al.,

(2001) who reveal that the process of hemp retting significant effects the local environment,

also advances this suggestion.

Figure 19. Peglar’s (1993) pollen stratigraphy of Quidenham Mere. There is a rapid increase

in Cannabaceae during the medieval period (QM–9b). After a gentle decline of Cannabaceae

at the end of subzone QM-9b, Cannabaceae increases rapidly to a maximum of 94% during

the post-medieval (QM-9c).

50

There is also evidence, however, to suggest that forest clearance may be a possible

explanation for the M/P-M eutrophication event. This relationship occurs as forest

clearance increases the total surface area of bare soil. The rate of erosion therefore

increases, as there is no vegetation to anchor the soil. It is then possible that a weathering

pulse would release chemical ions, such as sodium and potassium, from the sediment into

the lake, thus causing eutrophication (Figure 20) (Palmer, 2011). The geochemical data

shows that the concentration of potassium and sodium in the sediment increases between

800 - 685 cm, thus supporting the idea. Mackereth (1966), who documents that an

increased concentration of potassium and sodium in the geochemical record is an indication

of intense erosion, supports this idea. This view is also supported by Engstrom and Wight

(1984), Brubaker and Anderson (1993) and Foster and Lees (1999) who record that the

geochemistry of lake sediments can be used to deduce the stability of the surrounding area.

Furthermore, Boyle (2001) strongly argues that mineral enrichment, and thus the

concentration of sodium and potassium, is a fundamental indicator of soil erosion. The

magnetic susceptibility data, however, cannot be used to support this idea. This is because

there is a positive correlation between the concentration of magnetically susceptible

elements and the concentration of silica in the sediment. The magnetically susceptible

elements in the sediment do not therefore increase with soil erosion.

Figure 20. A proposed explanation of the medieval/post-medieval eutrophication event at

Quidenham Mere.

51

7.2.2. Possible causes of the second eutrophication event

There is evidence to suggest that anthropogenic activities are the cause of the second

eutrophication event at Quidenham Mere. This paper suggests that vegetation burning, due

to the development of Quidenham Mere, is a possible cause of this event. Peglar (1993),

who documents the high concentration of charcoal in the sediment at this time, supports

this idea. There are two reasons why this relationship exists. The first reason is that the

burning of vegetation would have caused an excessive input of nutrients to enter the Mere

(Figure 21). This idea coincides with Perrow (2002) who reveals that following vegetation

burning, a high proportion of the deposited nutrients are leached from the soil. Chapman

(1989), who documents that phosphorus is leached from the soil after vegetation burning,

advances this idea. Furthermore, Kenworthy (1964) reveals that potassium is rapidly

leached from the soil after burning. It is therefore possible that the excessive input of

nutrients into the Mere, due to vegetation burning, would have resulted in the second

eutrophication event at Quidenham Mere. The second reason to explain this relationship is

that the burning of vegetation would have caused an increased rate of soil erosion and thus

eutrophication (section 7.2.1) (Holden, 2008). The geochemical analysis supports this idea.

Figure 21. A proposed explanation of the most recent eutrophication event at Quidenham

Mere.

52

7.2.3. Summary

There is sufficient evidence to suggest that anthropogenic activities were the cause of both

eutrophication events at Quidenham Mere. A possible cause of the first eutrophication

event was hemp retting and/or forest clearance. A possible cause of the second

eutrophication event was vegetation burning. Anthropogenic activates are therefore a

legitimate explanation.

7.3. The effect of cultural eutrophication at Quidenham Mere upon the Mollusca phylum.

The concentration of molluscs in the sediment at Quidenham Mere is lowest in zone Q-1,

where only Gyraulus sp. and Pisidium sp. are present. A reason for this outcome is that this

zone, as documented in the work of Cheng, et al., (2007), resembles oligotrophic conditions.

The greatest concentration change of molluscs in the sediment occurred in zones Q-3 and

Q-4. A possible reason for this outcome is anthropogenic activities. The statistical testing

supports this idea as it shows that there is a mild positive correlation, to a 95% confidence

level, between the abundance of molluscs in the sediment and organic matter content.

Statistical testing however showed that there is a weak correlation, to a 95% confidence

level, between the abundance of molluscs in the sediment and the concentration of

potassium. This therefore suggests that the organic matter content had the greatest effect

upon the mollusc population out of these two variables. Statistical testing also showed that

there is no correlation between the population of molluscs in the sediment and the

concentration of sodium. This therefore suggests that the onset of the eutrophication

process did not affect the abundance of molluscs at Quidenham Mere. The species of

molluscs found at this location shall therefore be discussed to gain a fuller understanding of

the impacts of cultural eutrophication.

53

7.3.1. Bithynia tentaculata

Evidence suggests that the population of Bithynia tentaculata was affected by changes in

the organic matter content and the concentration of potassium in the sediment. Figure 18

shows that the population of Bithynia tentaculata initially increased during both episodes of

eutrophication at Quidenham Mere, but decreased towards the restoration process of the

Mere. The statistical analysis confirms this. The results therefore imply that the abundance

of this mollusc was altered by the episodes of cultural eutrophication at Quidenham Mere. A

possible explanation for the increased population of this mollusc is their ability to filter feed

in eutrophic waters (Brendelberger and Jiirgens, 1993). Legitimate reasons for the

decreased population of Bithynia tentaculata, however, include:

(i) Bithynia tentaculata are gill breathing and can only survive in well-oxygenated water

(Kerney, 1999; Dillon Jr., 2000),

(iI) Bithynia tentaculata are not able to migrate from their microhabitat after rapid

environmental change,

(iii) Bithynia tentaculata are intolerant to the toxic by-products of hemp retting, such as

hydrogen sulphide (Cheng, et al., 2007).

Cheng, et al., (2007) came to a similar outcome during their work on Bithynia tentaculata at

Quidenham Mere. Dussart (1979), who found a positive relationship between the

abundance of Bithynia tentaculata and the concentration of potassium, also came to a

similar conclusion. Furthermore, these results are in agreement with Ritcher (2001) who

documents an increased depth rate among the Bithynia tentaculata population following a

reduction in the concentration of dissolved oxygen (DO).

7.3.2. Gyraulus

Gyraulus laevis and Gyraulus sp. are discussed to identify the effects of cultural

eutrophication. Evidence suggests that the population of Gyraulus laevis was not affected by

changes in the organic matter content and the concentration of potassium in the sediment.

The statistical analysis confirms this. In other words, the abundance of mollusc was not

significantly altered by episodes of cultural eutrophication at Quidenham Mere. This finding,

54

however, contradicts Arter (1989), Nakamura and Kerciku (2000), Carlsson (2001), Salanki,

et al., (2003,) Jou and Liao (2006) and Timm, et al., (2006) which document that mollusc can

be used as an indicator of eutrophic conditions. This finding also contradicts Dussart (1979)

who found a negative correlation between this variable and the concentration of potassium

and a positive correlation between this variable and the concentration of sodium.

There is also evidence to suggest that the population of Gyraulus sp. was affected by

changes in the organic matter content and the concentration of potassium in the sediment.

Figure 18 shows that the population of Gyraulus sp. initially increased during both episodes

of eutrophication at Quidenham Mere, but decreased towards the restoration process of

the Mere. The statistical analysis confirms this. The results therefore imply that the

abundance of this mollusc was altered by the episodes of cultural eutrophication at

Quidenham Mere. A possible explanation for the increased population of this mollusc is that

they are tolerant to slight eutrophic conditions (Lsyne and Clark, 2009). A legitimate reason

for the decreased population of Gyraulus sp., however, is that they cannot survive in

oxygen-depleted waters (Alder, 1838). Furthermore, these molluscs are intolerant to

hydrogen sulphide (Caldwell, 1975).

7.3.3. Lymnaea

Lymnaea peregra and Lymnaea sp. are discussed to identify the effects of cultural

eutrophication. In recent years, a dispute has arisen as to whether this species can be used

as an indicator of eutrophication. The results from this study shall therefore advance our

knowledge in this field.

Evidence suggests that the population of Lymnaea peregra was not affected by changes in

the organic matter content or the concentration of potassium and sodium. The abundance

of this mollusc was therefore not significantly altered by the episodes of cultural

eutrophication at Quidenham Mere. This finding coincides with Fitter and Manuel (1986)

who document that this species of mollusc are able to survive in a wide variety of

freshwater habitats. This finding, however, contradicts Dussart (1979) who found a positive

55

correlation between the population of Lymnaea peregra and the concentration of

potassium. Dussart (1979) also found a negative correlation between this variable and the

concentration of sodium. This finding therefore challenges existing literature.

There is evidence however to suggests that the population of Lymnaea sp. was affected by

changes in the organic matter content and the concentration of potassium in the sediment.

Figure 18 reveals that the population of Lymnaea sp. initially increased during both episodes

of eutrophication at Quidenham Mere, but decreased towards the restoration process of

the mere. The statistical analysis confirms this. It is therefore likely that the abundance of

this mollusc was altered by the episodes of cultural eutrophication at Quidenham Mere. A

possible explanation for the increased population of this mollusc is that they are able to

survive in oxygen-depleted waters. This is because they are able to hang from the surface of

the water and take in oxygen through its pneumostome (Figure 22 and 23) (Clifford, 1991).

Furthermore, the snail is able to undergo phonological plasticity in order to responds to

periods of low DO (Lodge and Kelly, 1985). A possible explanation for the decreased

population of this mollusc is that they are intolerant to hydrogen sulphide (Calderwell,

1975). Dussart (1979) came to a similar outcome when studying this snail in North West

England.

Figure 22. Diagram of a Lymnaea snail

with the main features labelled.

56

Figure 23. In order to survive in periods

of low DO, the snail hangs suspended

from the upper surface of the water by

its foot. The snail subsequently takes in

oxygen by opening its pneumostome

(Clifford, 1991).

7.3.4. Valvata

Valvata piscinalis and Valvata macrostoma are discussed to identify the effects of cultural

eutrophication. These molluscs have been discussed under the title Valvata, as the results of

the statistical analysis are the same for both species.

Evidence suggests that the population of Valvata was affected by changes in the organic

matter content and the concentration of potassium. Figure 18 shows that the population of

Valvata initially increased during both episodes of eutrophication at Quidenham Mere, but

decreased towards the restoration process of the Mere. The statistical analysis confirms this

(Table 2). It is therefore likely that the abundance of this mollusc was altered by the

episodes of cultural eutrophication at Quidenham Mere. A possible explanation for the

increased population of this mollusc is that the snail is able to survive periods of

eutrophication due to behavioural and physiological plasticity (Lodge and Kelly, 1985).

Furthermore, these molluscs are effective competitors in eutrophic waters, as they can feed

on suspended particles (Grigorovich, et al., 2005). A key explanation for the decreased

population of this mollusc is that it is intolerant to hydrogen sulphide (Calderwell, 1975).

Foot

57

7.3.5. Pisidium

Evidence suggests that the population of Pisidium sp. was affected by changes in the organic

matter content and the concentration of potassium. Figure 18 shows that the population of

Pisidium sp. initially increased during both episodes of eutrophication at Quidenham Mere,

but decreased towards the restoration process of the mere. The statistical analysis confirms

this (Table 2). It is therefore likely that the abundance of this mollusc was altered by the

episodes of cultural eutrophication at Quidenham Mere.

7.3.6. Summary

There is sufficient evidence to suggest that anthropogenic activities at Quidenham Mere

initially caused the population of Bithynia tentaculata, Gyraulus sp, Lymnaea sp., Valvata

piscinalis, Valvata macrostoma and Pisidium sp. to increase. This finding coincides with

Cheng, et al., (2007) who found that an increased concentration of nutrients at Quidenham

Mere caused the population of molluscs to enlarge. There is also evidence to suggest that

the eutrophication process caused the population of these molluscs to decline. A wide range

of literature supports this finding.

58

Chapter 8: Conclusion

8.1. Summary of main findings

The information presented in this paper represents a substantial increase in the range and

quality of data from Quidenham Mere. A new geochemical record provides the

environmental history of Quidenham Mere since the medieval period. This geochemical

record suggests the occurrence of two episodes of cultural eutrophication at Quidenham

since the medieval period. This challenges previous literature, as only one episode of

cultural eutrophication has been recorded at Quidenham Mere. This is therefore a

significant new finding.

The first episode of eutrophication occurred at approximately 800 – 685 cm (medieval/post-

medieval period). Reasons for this outcome include the use of Quidenham Mere as a hemp-

retting pit. Hemp retting would have released a great quantity of nutrients and organic

matter into the Mere, thus causing eutrophication (Cox, et al., 2001; Cheng, et al., 2007).

An additional reason is the clearance of Quercus and Corylus avellana, which would have

resulted in an increased rate of soil erosion into the Mere. The increased input of nutrients

into the Mere, due to soil erosion, may have then promoted eutrophication. This idea

coincides with Peglar (1993) and the geochemical data.

The second episode of eutrophication occurred at approximately 455 – 325 cm (the last 200

years). A reason for this outcome is the burning of vegetation due to the development of

Quidenham Mere Parkland. This idea coincides with the work of Peglar (1993). An increased

rate of soil erosion, due to the clearance of vegetation, may have caused the eutrophication

process. The burning of vegetation may have also caused the leaching of an excessive

quantity of nutrients into the Mere, thus causing eutrophication.

This investigation also provides an accurate mollusc record of Quidenham Mere since the

medieval period. The data shows that Bithynia tentaculata, Gyraulus sp., Valvata piscinalis,

Valvata macrostoma, and Pisidium sp. were affected by anthropogenic activities at

Quidenham Mere. Changes in the percentage of organic matter content caused the greatest

change to the abundance of molluscs. The ending period of the eutrophication process, as

indicated by increased potassium levels, caused the next greatest change to the population

59

of these molluscs. The beginning period of the eutrophication process, as indicated by

increased sodium levels, did not cause a significant change to the population of molluscs.

8.2. The aims of the literature

Overall, the three aims of this literature have been fulfilled to the highest ability possible.

The objectives of this literature have also been fully achieved. Episodes of cultural

eutrophication have been identified by the analysis of the organic matter content, the

potassium concentration and the sodium concentration. Statistical testing also provided

further confirmation. The dating of the eutrophication process, however, requires further

investigation. The first reason for this outcome is that the sediments of Quidenham Mere

cannot be accurately dated. Comparing the sediment composition of Quidenham Mere

with the sediment composition of Peglar (1993) only provided a tentative chronology.

Furthermore, as the phenomenon of eutrophication is a process, a start and end cannot be

identified, and thus dated. Despite this criticism, there is strong evidence to suggest that the

dates recorded in this literature can be used to determine when the Mere experienced

eutrophic conditions, and hence aim number one has been addressed.

Possible explanations as to why the mere experienced cultural eutrophication have been

determined by the analysis of the geochemical record. The magnetic susceptibility results

were, however, unable to add additional support to the conclusions proposed. Nonetheless,

this paper fully supports the idea that anthropogenic activities were the key cause of

eutrophication at Quidenham Mere. Several explanations for each episode of

eutrophication have been documented, and there is strong evidence to accept that the

explanations provided in this literature are legitimate. Furthermore, Peglar (1993) and

Cheng, et al., (2007) supports several of the conclusions proposed in this literature. Aim

number two has therefore been addressed an answered successfully.

60

Changes in the abundance of molluscs have been recorded at Quidenham Mere since the

medieval period. There is evidence to suggest that these changes were caused by cultural

eutrophication. This is because the quantitative zonation analysis places zone boundaries at

the onset of the eutrophication process. The Spearman’s rho test furthers this idea.

However, due to the limitations of the statistical testing (section 8.2) one cannot conclude

that the mollusc population changed due to episodes of cultural eutrophication. Additional

factors may have caused this correlation to be present. Aim number three has therefore

been addressed, but conclusion regarding this aim cannot be produced.

8.2. Limitations of the study

The recognised limitations of this study regard the third aim. For example, the total number

of species extracted from the sample was relatively low. This could not be prevented,

however, as the species acquisition curve revealed that 20 g of sediment was the optimum

sample weight to extract. Additionally, Bithynia sp. may be over represented due to their

thick operculum (Sparks, 1964). Conclusions regarding aim three, therefore, may not be

accurate. Furthermore, correlations and associations do not necessarily imply causation.

Therefore, the results of this study cannot be used to prove that cultural eutrophication

caused the population of molluscs to change; one can only state that there is a correlation

between these two variables.

8.3. Significance of the findings

The overall aim of this paper was to identify the causes of cultural eutrophication at

Quidenham Mere and to document the effects this phenomenon had upon the mollusc

population. In interpretation of the data, it must be realised that the results are only

representative of this location. The conclusions proposed are therefore only legitimate for

Quidenham Mere. Despite this, a significant body of work has accumulated documenting

the negative effects of cultural eutrophication upon the abundance of molluscs, in various

locations. This paper therefore supports this correlation. Furthermore, this paper adds to

the wider issue of environmental change. This is because there is a growing concern that

anthropogenic activities are causing a decline in biodiversity (Huggett, 2010). Future

61

management issues regarding anthropogenic activities can therefore be addressed

appropriately with knowledge of this paper and similar studies.

8.4. Scope for further study

Regarding Quidenham Mere, further studies incorporating a larger population of molluscs is

needed to understand fully the effects of cultural eutrophication. Furthermore, an accurate

dating technique is needed to allow a greater understanding of the causes of cultural

eutrophication at this location. There is also significant scope for further studies regarding

the topic of cultural eutrophication. This is because the interest in this area declined in the

1980s due to a heightened interest in acidification (Smol, 2002). Further studies in this area

will enhance the knowledge of the impacts of cultural eutrophication and allow the field to

become more predictive. Additionally, it will act as a basis of how to manage future cultural

eutrophication problems, and thus prevent environmental change.

62

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Chapter 10: Appendix

10.1. Methodology

A detailed methodology is provided for loss-on-ignition, geochemical analysis and mollusc

analysis.

10.1.1. Loss-on-ignition

In order to perform this loss-on-ignition, samples were taken every 5 centimetres along the

core. This stratified sampling strategy was chosen in order to allow an accurate comparison

with Peglar (1993). The weights of the crucibles were then measured (Wc) and filled 2/3 full

of sediment. Following this, the crucibles were re-weighed (Wcs), positioned on a metal tray

and placed in a muffle furnace at 105°C. After 24 hours, the temperature of the furnace was

lowered to 50°C for safety reasons. The samples were then transferred to a desiccator to

cool. After cooling, the weight of the crucible and ignited soil were then weighed (Wd) and

the percentage moisture was therefore calculated using the following formula: 100 x (Wcs -

Wd)/ (Wd- Wc). This process was repeated at 450°C and 950°C to calculate the organic and

carbonate content of the core, respectively. Calculations following the standard procedure

of Heiri, et al., 1999 were used to calculate the values of these variables.

10.1.2. Geochemical Analysis

In order to perform the electrometric method, a 20 g sample was mixed with 50 ml of

deionised water and allowed to equilibrate (Sarkar, 2005). An electrode was then inserted

into the mixture and the pH was read directly of the meter (Cheswoth, 2008). To prepare

the samples for the FAAS, 5g of air dried soil was weighed and carefully placed into a clean,

dry shaking bottle. As the entire pH results were > 5, the samples were mixed with 125 mL

of 1M ammonium acetate. The solutions were then placed on a shaker for 1 hour, in order

to ensure that the samples were thoroughly mixed. The final preparation step was to filter

the solutions through Whatman number 1 filter paper, ensuring that the first 5-10 mL was

77

rejected. Whatman number 1 filter paper was used, as it is the appropriate piece of

equipment for this process (Whatman, 2009). The samples were then analysed using FAAS.

10.1.3. Molluscs Analysis

20g samples were extracted every 10 cm along the core. This stratified sampling method

was designed to produce a reliable set of data. The sediment samples were then digested

using 30ml of c. 10% hydrogen peroxide and 70 ml distilled water. The samples were then

placed in a fume cupboard overnight in order to digest. To extract the molluscan remains,

the liquid samples were passed through a 125-micron sieve and were thoroughly washed

with deionised water to remove any chemical residue. The molluscan remains were then

removed with the aid of a moistened brush under a low powered binocular microscope as

recommended by the literature of Lowe and Walker (1997).

10.2. Results

Sets of results that are too large to be incorporated into the main body of the literature,

have been recorded in this section. The purpose of including them is to allow further

research to be undertaken. This will allow a greater understanding of the topics highlighted

in this literature.

10.2.1. Sediment lithology

A summary of the sediment composition of QUID1, as determined by the Troles-Smith, is

shown in Table 4.

10.2.2. Sediment composition

A summary of the results from the loss-on-ignition are shown in Table 5.

78

Depth (cm) Colour Description

Nigror (Nig) Stratificatio (Strf)

Elasticitas (Elas)

Siccitas (Sicc)

Sediment Composition

Notes

125-161 Dark Brown 3 0 3 3 Th4 [part.test.(moll)1]. Lower Boundary very gradual over 1.5 cm.

161-197 Light Brown 2 0 3 3 Dh2, Gs2 [part.test.(moll)1]. Lower boundary sharp over 0.5 mm.

197-210 Light brown dark Brown

4 0 3 3 Tb Sphagni1, Dh2, Gs1

[test.(moll)1]. Lower boundary sharp over 0.5 mm.

210-268 Dark Brown 2 1 3 3 Tb Spagni3, Dh1 [part.test.(moll)1]. Lower boundary gradual over 1.5. cm.

268-360 Dark Brown/black

1 2 3 2 Tb Spagni4 [part.test.(moll)1]. Lower boundary very gradual over 1 cm.

360-519 Darkish cream/Beige

1 3 3 2 Ag2, Lc2, [part.test.(moll)1]. Lower boundary gradual over 1.5 cm.

519-620 Creamy-white 1 1 3 2 Ag1, Lc3

part.test.(moll)1]. Lower boundary very gradual over 1.75 cm.

620-662 Darkish cream/Beige

1 3 4 2 As3, Lc1 part.test.(moll)1]. Lower boundary very gradual over 1.75 cm.

662-775 Creamy-white 1 1 4 1 As1, Lc3 [part.test.(moll)1]. Lower boundary gradual over 2 mm. In middle of core at approximately 740 cm there is a detrital layer of 1 cm

775 - 802 Darkish cream/Beige

2 2 3 2 As3, Lc1 part.test.(moll)1]. Lower boundary sharp over 1 mm

802 – 830

Darkish cream 3 2 2 2 As3, Lc1

Table 3. Sediment lithology using the terminology of Troels-Smith (1955). The work of Birks and Birks (1980) also provided additional support.

79

Sample depth (cm) Cruicible mass (g) Cruc. + wet sed. mass (g) Cruc. + dry sed. mass (g) Wight after 450°C (g) Wight after 950°C (g)

125 11.2876 16.1689 12.0539 11.3497 11.32

130 10.8207 15.6001 11.5213 11.0676 10.879

135 11.9403 16.1098 12.5742 12.0222 12.0017

140 10.9566 15.9163 12.1545 11.727 11.5095

145 11.1739 16.176 12.149 11.6983 11.5822

150 11.5517 15.2443 12.0683 11.6493 11.6261

155 12.933 17.4657 13.717 13.2352 13.1181

160 11.896 16.7134 13.0663 12.7891 12.375

165 11.7836 17.701 13.7966 13.5376 12.5385

170 11.7973 17.9559 14.1499 13.9288 13.2185

175 11.1141 17.7948 13.6686 13.3862 12.6076

180 12.1855 16.3706 13.5824 13.3407 12.8977

185 12.4256 17.336 13.8243 13.4237 13.0678

190 11.8112 16.731 13.2142 12.8838 12.3985

195 12.5381 16.9863 13.2798 12.9732 12.6717

200 12.41 17.6742 13.2969 12.7928 12.5935

205 11.5896 16.0577 12.5288 12.0264 11.7975

210 10.2419 15.4156 11.5784 11.0524 10.7687

215 12.3908 17.9546 12.9073 12.6709 12.4987

220 10.857 16.9302 14.5226 14.2107 13.0215

225 10.864 16.954 11.7859 11.4089 11.0971

230 11.1459 16.7183 13.2704 13.053 12.5076

235 12.3074 17.7189 14.1209 13.8532 13.4894

240 11.8276 16.955 13.8569 13.5687 13.1951

245 11.4047 17.4041 14.0987 13.4586 12.8239

250 12.2769 17.4108 14.3205 14.1871 13.603

255 11.2189 16.6407 13 12.9196 12.18

80

260 11.1821 16.215 12.98 12.8795 12.0846

265 12.5938 17.7949 14.7551 14.5694 14.0586

270 11.1969 16.4781 13.1478 12.946 12.5294

275 11.4563 16.601 13.509 13.3515 12.5374

280 11.0901 17.4464 13.8299 13.6228 12.5299

285 10.7018 15.7795 13.0687 12.9867 12.0138

290 12.2913 16.816 14.3505 13.9856 13.3135

295 10.7595 17.2386 13.9221 13.5995 12.4993

300 10.7866 15.9845 13.2705 13.1688 12.1378

305 6.6582 11.1899 8.4613 7.9713 7.3169

310 10.8328 16.3305 13.2236 13.0076 12.0479

315 10.9607 16.3379 13.4455 13.3656 12.0158

320 10.2035 15.943 12.9157 12.5911 11.4433

325 12.2316 17.0506 14.6184 14.0245 13.2456

330 13.9368 18.6257 16.1231 15.4554 14.6052

335 12.0931 16.6432 14.5087 13.55923 12.8146

340 10.2953 15.0855 12.6822 11.997 11.0716

345 13.5117 18.5166 15.8303 15.0194 14.3967

350 11.154 16.5627 13.7948 12.728 11.9996

355 10.7562 16.3066 13.59 12.3798 11.6965

360 11.6404 16.8096 14.1288 13.5087 12.6196

365 10.4966 15.5944 13.9424 13.2443 12.0101

370 11.2457 16.0783 13.5537 13.0957 12.2228

375 11.7027 16.8135 14.0122 13.5519 12.4401

380 10.6447 15.9462 13.3105 12.8162 11.4069

385 11.9517 16.3815 13.3105 12.9985 12.2012

390 6.2301 11.2074 8.657 8.2418 7.0899

395 6.5952 11.2434 8.9288 8.6083 7.4007

81

400 7.3536 12.4436 9.9004 9.6023 8.2562

405 6.6249 11.7446 9.1354 8.9321 7.58733

410 11.8513 16.9564 14.4543 14.3245 12.8973

415 11.192 16.5582 14.0032 13.8698 12.9789

420 11.0873 16.0111 13.7669 13.6781 12.8101

425 12.7846 17.6752 15.3374 15.2576 14.4116

430 10.545 15.321 13.2117 13.0277 12.0184

435 11.1772 16.5785 13.9889 13.7087 12.6039

440 11.2369 17.2432 14.4134 14.1217 12.7966

445 10.9078 16.2275 13.7161 13.3368 12.3136

450 12.5811 17.5927 15.2532 14.9865 14.0145

455 11.9597 17.7234 14.8467 14.2585 13.1222

460 11.6273 16.3927 14.059 13.7889 12.76034

465 12.2735 18.6796 15.5919 15.2996 13.8181

470 10.2126 15.4862 13.2029 13.0144 11.6722

475 11.1342 17.4541 14.3693 14.0742 12.7228

480 11.4043 16.4249 13.9102 13.7839 12.6769

485 10.8131 15.9519 13.4337 13.3454 12.1964

490 11.5193 16.3167 13.8269 13.7496 12.6901

495 11.0656 16.9203 14.1081 14.007 12.7807

500 11.0983 16.0964 13.8011 13.7108 12.4895

505 11.6798 16.7832 14.3795 14.3137 13.0014

510 11.7493 16.7411 14.4783 14.3712 13.0594

515 12.0783 17.1009 14.9844 14.8759 13.8089

520 12.6324 17.7001 15.7044 15.6094 14.4116

525 10.335 15.484 13.5491 13.2108 11.9882

530 11.0449 16.005 13.7793 13.6841 12.6501

535 11.646 16.459 14.2209 14.0953 12.9413

82

540 12.2165 17.763 15.2556 15.1439 13.8849

545 12.239 17.978 15.448 15.3443 13.9179

550 6.7811 11.6438 9.3053 9.1971 8.0062

555 6.55 11.495 9.229 9.136 7.9304

560 6.3624 11.983 9.2884 9.1759 7.8166

565 6.5899 12.2964 9.6424 9.5279 8.0236

570 6.8799 11.5333 9.0165 8.8789 7.7196

575 6.5046 11.2404 9.2602 9.1458 7.8057

580 12.5748 16.6654 13.6852 13.5474 12.9689

585 11.2055 16.246 13.9473 13.8382 12.3282

590 11.479 16.3713 14.0564 13.9569 12.6916

595 12.2628 17.1983 14.9277 14.8055 13.4068

600 13.3351 18.4735 15.6164 15.4816 14.4133

605 11.9413 16.7134 14.4126 14.2639 13.0999

610 11.8797 16.8109 14.4189 14.2512 12.9005

615 11.645 16.5987 14.3986 14.2009 12.8847

620 12.9873 17.8964 15.6753 15.4984 14.0937

625 11.0667 16.0519 13.398 13.2911 11.8613

630 10.8465 15.6146 13.0705 12.9648 11.8472

635 11.0157 16.593 13.6806 13.531 12.2492

640 11.3797 16.5077 13.8349 13.7403 12.6097

645 10.6511 15.9599 13.2914 13.1799 11.9683

650 12.3828 16.9496 14.652 14.5575 13.5123

655 12.5295 16.9358 14.297 14.156 13.3141

660 11.8602 16.4813 14.0627 13.9578 12.9452

665 11.3152 16.7774 13.8651 13.7273 12.6997

670 11.1427 16.5013 13.9092 13.8074 12.6778

675 12.081 17.16 14.4843 14.36 13.3643

83

680 11.0515 16.4993 13.6253 13.5285 12.5461

685 12.0062 16.8854 14.4962 14.359 13.3396

690 11.1243 16.1933 13.577 13.4358 12.4258

695 11.7822 16.1699 14.158 14.0524 12.9663

700 11.9489 16.8717 14.4746 14.343 13.1253

705 11.7595 16.7392 14.3986 14.2686 12.9678

710 11.4964 16.7934 14.1497 13.9943 12.3194

715 6.6534 11.1515 10.5248 10.1963 7.6826

720 6.4375 11.3928 9.5984 9.2787 7.3112

725 6.4214 11.9063 10.2664 9.7448 7.4926

730 6.6241 11.9107 9.8435 9.1427 6.9942

735 6.5377 11.7932 10.2664 9.2499 7.0024

740 7.3629 12.7801 9.8435 9.2397 7.8262

745 6.3546 11.7836 8.6796 8.1869 6.9789

750 6.5056 11.805 10.1616 8.8634 7.0641

755 6.4981 11.5404 9.0298 8.4652 7.0358

760 6.7456 11.7794 9.243 8.5624 7.0021

765 6.4871 11.9781 9.7956 8.6946 6.5001

770 7.3329 12.3487 10.3758 9.3332 7.3343

775 6.9532 11.9993 10.4983 9.3524 6.9953

780 11.4973 16.5993 14.1097 13.497 11.7629

785 11.4084 16.4397 14.4596 14.0074 12.3986

790 6.7317 11.7245 11.0948 10.5061 8.3956

795 6.7725 11.4627 11.0133 10.6033 8.6186

800 6.516 11.3865 11.099 10.7356 8.6926

805 7.0158 12.5462 12.196 11.6697 9.41348

810 7.291 12.1547 11.8622 11.6704 9.7458

815 6.5375 11.2982 10.9425 10.6974 8.5486

84

820 6.5964 11.4269 11.0665 10.8783 8.8911

825 6.5506 11.6237 11.2508 11.0138 8.8863

830 6.4533 11.6545 11.2128 11.0079 8.1501

Table 4. Results from the loss-on-ignition analysis. The silica content in this literature was calculated by the following formula: 100 - (organic +

carbonate).

10.2.3. Geochemical Analysis

Depth (cm) Sodium concentration (mg/kg) Potassium concentration (mg/kg)

125 87.74378814 11.96506202

135 68.61080398 11.10606539

145 74.32098765 11.35802469

155 114.5721978 15.83719365

165 118.2378039 19.62244405

175 126.4147589 18.51778695

185 92.71930346 13.63519169

195 91.73493068 24.54529226

205 133.0777436 12.07510717

215 73.006023 13.18164304

225 117.8796676 10.26128742

235 76.59437233 6.550834476

245 94.73984684 18.2097368

255 129.2731269 14.22740296

265 100.8521887 13.80861263

275 75.77435856 16.61497563

285 100.7924025 9.705935055

295 92.98727381 7.428735373

85

305 76.12759286 6.281154526

315 78.30439512 8.057043871

325 78.96702055 8.073305615

335 79.24931933 5.105017503

345 74.46723442 132.9415057

355 93.2779834 159.2977893

365 72.61744427 15.07628601

375 99.93337775 158.2278481

385 80.27096345 157.8499129

395 342.6156141 14.66931875

405 147.2028951 1.499520154

415 160.4579665 3.493641572

425 211.5609618 5.295328008

435 308.4964238 9.087872357

445 290.3668825 11.77163037

455 210.0587563 6.26666934

465 62.23328592 2.469574838

475 74.97110748 2.988881361

485 86.47019559 9.86063634

495 139.0480518 4.445586027

505 130.9766022 2.543234995

515 75.31530003 2.993354752

525 51.32612967 2.701375246

535 131.0084919 6.214824096

545 131.2552502 8.500340014

555 52.53356173 9.958969048

565 106.5830412 21.66121854

575 63.25408795 11.6585966

86

585 80.9565952 6.536867935

595 135.9102992 0.749505326

605 64.79008014 8.970934173

615 61.738887 12.74770541

625 89.75031261 9.832197168

635 80.43044154 7.563991367

645 71.33939718 10.15595585

655 132.3684263 12.41730078

665 121.5635399 3.961337347

675 89.61632396 7.87835815

685 105.2890801 30.90825024

695 64.24503403 4.712956165

705 53.7381776 48.98922237

715 58.23485894 50.2369384

725 53.50136726 51.51983514

735 165.5427981 71.6339631

745 191.813933 69.20345817

755 198.9524544 81.71261521

765 200.7921388 70.18951168

775 199.5878186 22.76001441

785 191.3433624 5.582962828

795 159.0633219 17.95468339

805 129.3928757 1.745183294

815 131.0413553 15.44593921

825 131.1948981 13.49433238

Table 5. Geochemistry results regarding the concentrations of potassium and sodium in the sediment of Quidenham Mere.

87

10.2.4. Magnetic Susceptibility

10.2.4.1. Upper Section (125 – 513 cm)

Depth (cm) Magnetic Susceptibility (SI)

Depth (cm) Magnetic Susceptibility (SI)

Depth (cm) Magnetic Susceptibility (SI)

125 0

255 -3.9

385 -4.4

127 -0.1

257 -4

387 -4.3

129 -0.2

259 -4.1

389 -4.3

131 -0.5

261 -4

391 -4.3

133 -0.6

263 -4

393 -4.2

135 -0.6

265 -4.1

395 -4.3

137 -0.7

267 -4.1

397 -4.3

139 -0.9

269 -4.1

399 -4.3

141 -0.9

271 -4.2

401 -4.3

143 -1

273 -4.1

403 -4.3

145 -1.2

275 -4.2

405 -4.2

147 -1.3

277 -4.2

407 -4.3

149 -1.3

279 -4.2

409 -4.2

151 -1.5

281 -4.2

411 -4.2

153 -1.5

283 -4.3

413 -4.2

155 -1.5

285 -4.2

415 -4.2

157 -1.6

287 -4.3

417 -4.1

159 -1.6

289 -4.3

419 -4

161 -1.7

291 -4.2

421 -4

163 -1.7

293 -4.3

423 -3.9

165 -1.8

295 -4.3

425 -3.8

167 -1.9

297 -4.4

427 -3.9

169 -1.9

299 -4.3

429 -3.8

171 -2

301 -4.4

431 -3.8

88

173 -2.1

303 -4.3

433 -3.8

175 -2.2

305 -4.4

435 -3.8

177 -2.2

307 -4.3

437 -3.9

179 -2.2

309 -4.3

439 -3.8

181 -2.4

311 -4.3

441 -3.8

183 -2.4

313 -4.4

443 -3.9

185 -2.5

315 -4.4

445 -3.9

187 -2.5

317 -4.4

447 -4

189 -2.6

319 -4.3

449 -4

191 -2.6

321 -4.2

451 -3.9

193 -2.6

323 -4.1

453 -4

195 -2.6

325 -4

455 -4

197 -2.6

327 -3.9

457 -4

199 -2.7

329 -4

459 -4

201 -2.7

331 -3.9

461 -4

203 -2.7

333 -3.9

463 -4

205 -2.8

335 -3.9

465 -4.1

207 -2.8

337 -3.9

467 -4.1

209 -2.9

339 -3.9

469 -4.1

211 -2.9

341 -4

471 -4.2

213 -2.9

343 -3.9

473 -4.2

215 -3

345 -4

475 -4.2

217 -2.9

347 -4

477 -4.2

219 -2.9

349 -4

479 -4.3

221 -2.8

351 -4

481 -4.2

223 -2.8

353 -4.1

483 -4.3

225 -2.7

355 -4

485 -4.3

227 -2.6

357 -4

487 -4.3

89

229 -2.7

359 -4.1

489 -4.4

231 -2.8

361 -4.2

491 -4.4

233 -2.9

363 -4.2

493 -4.3

235 -3

365 -4.3

495 -4.3

237 -3.4

367 -4.2

497 -4.4

239 -3.4

369 -4.3

499 -4.4

241 -3.5

371 -4.3

501 -4.4

243 -3.6

373 -4.3

503 -4.5

245 -3.7

375 -4.3

505 -4.4

247 -3.8

377 -4.3

507 -4.3

249 -3.8

379 -4.2

509 -4.4

251 -3.9

381 -4.3

511 -4.4

253 -3.9

383 -4.3

513 -4.5

Table 6. Magnetic susceptibility results from the upper section of the core.

10.2.4.2. Lower Section (515 – 829 cm)

Depth (cm) Magnetic Susceptibility (SI)

Depth (cm) Magnetic Susceptibility (SI)

Depth (cm) Magnetic Susceptibility (SI)

515 -4.4

643 -10.8

771 -12.6

517 -4.3

645 -10.8

773 -12.7

519 -4.4

647 -10.9

775 -12.9

521 -4.4

649 -11

777 -12.9

523 -4.4

651 -10.9

779 -13.2

525 -4.4

653 -11

781 -13.2

527 -4.9

655 -11.1

783 -13.2

529 -5

657 -11.2

785 -13.1

531 -5.1

659 -11.4

787 -13.2

533 -5.3

661 -11.4

789 -13.2

90

535 -5.3

663 -11.4

791 -13.2

537 -5.5

665 -11.6

793 -13.2

539 -5.7

667 -11.6

795 -13.2

541 -5.9

669 -11.4

797 -13.2

543 -6

671 -11.7

799 -13.1

545 -6.1

673 -11.8

801 -13.2

547 -6.2

675 -11.9

803 -13.2

549 -6.4

677 -11.9

805 -13.1

551 -6.5

679 -12.1

807 -13.3

553 -6.6

681 -12.1

809 -13.3

555 -6.7

683 -12.2

811 -13.4

557 -6.9

685 -12.2

813 -13.4

559 -6.9

687 -12.3

815 -13.4

561 -7.1

689 -12.3

817 -13.4

563 -7.2

691 -12.4

819 -13.5

565 -7.3

693 -12.4

821 -13.5

567 -7.5

695 -12.4

823 -13.4

569 -7.6

697 -12.4

825 -13.5

571 -7.7

699 -12.3

827 -13.5

573 -7.8

701 -12.4

829 -13.5

575 -7.9

703 -12.4 577 -8

705 -12.4

579 -8.1

707 -12.4 581 -8.2

709 -12.4

583 -8.4

711 -12.4 585 -8.5

713 -12.1

587 -8.6

715 -12.4 589 -8.7

717 -12.3

91

591 -8.8

719 -12.1 593 -8.8

721 -12.3

595 -8.9

723 -12.3 597 -9

725 -12.2

599 -9.1

727 -12.1 601 -9.2

729 -12

603 -9.2

731 -12 605 -9.3

733 -12.1

607 -9.3

735 -12.1 609 -9.4

737 -12.1

611 -9.2

739 -12.1 613 -9.3

741 -12.3

615 -9.2

743 -12.2 617 -9.3

745 -12.2

619 -9.2

747 -12.2 621 -9.3

749 -12.3

623 -9.3

751 -12.3 625 -9.9

753 -12.4

627 -10.1

755 -12.3 629 -10.2

757 -12.4

631 -10.3

759 -12.5 633 -10.3

761 -12.5

635 -10.3

763 -12.6 637 -10.3

765 -12.5

639 -10.5

767 -12.5 641 -10.6

769 -12.6

Table 7. Magnetic susceptibility results from the lower section of the core.

92

10.2.5. Mollusc Analysis

Depth (cm) Bithynia tentaculata

Valvata piscinalis

Valvata macrostoma

Lymnaea peregra

Lymnaea sp. Gyraulus laevis

Gyraulus sp.

Pisidium sp.

125 6 3 5 3 6 4 3 9

135 5 5 4 3 5 1 3 10

145 5 3 6 5 6 4 6 5

155 4 2 7 3 7 6 5 6

165 6 5 5 4 7 5 4 11

175 4 1 6 4 4 3 6 14

185 4 3 5 3 6 7 3 12

195 5 3 4 3 7 4 7 10

205 4 3 4 2 6 5 5 9

215 2 2 4 1 3 4 8 8

225 2 5 3 1 3 3 6 6

235 4 3 2 3 5 5 4 10

245 3 2 1 3 3 4 5 8

255 2 4 3 2 2 5 6 9

265 3 2 2 3 4 1 5 7

275 4 4 3 3 5 0 7 5

285 3 2 2 2 4 5 6 6

295 3 2 1 4 4 4 5 8

305 2 2 2 1 4 5 8 6

315 1 2 1 1 1 4 7 7

325 3 1 2 4 2 3 5 6

335 5 3 2 10 5 7 6 5

345 9 10 9 19 17 14 20 7

355 8 7 8 17 18 20 15 8

93

365 9 6 11 22 20 14 15 8

375 8 8 9 22 22 5 16 10

385 6 6 7 16 21 10 11 6

395 2 2 4 4 4 5 5 2

405 2 5 1 3 5 5 3 1

415 2 3 1 4 4 2 4 2

425 4 4 4 5 4 1 6 1

435 2 2 2 6 2 1 3 1

445 3 2 2 4 4 2 6 3

455 3 5 1 5 3 3 5 3

465 4 4 1 5 6 1 4 4

475 3 3 2 3 4 2 2 6

485 3 2 2 4 4 3 2 5

495 2 2 1 5 3 2 2 7

505 2 2 2 3 3 0 3 6

515 3 4 3 3 4 2 3 4

525 1 2 2 1 1 2 2 5

535 1 4 1 1 1 2 5 3

545 2 3 2 1 1 1 3 4

555 2 2 2 2 1 2 4 6

565 3 2 4 2 1 0 4 5

575 2 2 2 3 2 2 3 5

585 2 3 4 3 1 1 3 4

595 2 3 2 4 3 1 3 6

605 1 2 1 2 1 1 2 5

615 1 1 2 3 4 1 4 4

625 1 1 1 1 2 1 4 3

635 2 1 3 1 2 3 0 6

94

645 2 2 2 2 2 2 1 5

655 1 1 1 2 3 2 1 7

665 2 2 1 3 4 2 2 2

675 2 2 1 1 4 2 1 3

685 1 2 2 0 4 0 5 6

695 1 2 3 2 2 2 1 5

705 3 1 2 2 2 1 2 7

715 3 1 1 1 5 1 4 6

725 2 1 3 1 2 0 4 5

735 2 1 1 1 5 1 3 4

745 6 7 8 5 6 4 3 4

755 8 8 7 8 6 6 5 3

765 7 7 5 6 5 5 6 4

775 2 3 2 0 2 2 0 1

785 4 4 3 1 1 3 0 2

795 5 1 2 0 1 1 1 2

805 4 1 1 0 0 1 0 2

815 3 2 1 0 1 0 1 1

825 3 1 1 0 1 1 0 1

830 0 0 0 0 0 0 1 1

Table 8. Results from the mollusc analysis. Concentrations of molluscs are in the following units: concentration per 20g.

95

10.3. DSG Reflective log.

The purpose of the DSG meetings was to provide support to other students. At the

beginning of this module, I found the task of planning, undertaking and writing the

dissertation very daunting. However, the DSG meetings made the process significantly

easier. The peer-group meetings were helpful for support and encouragement. They

provided a time to discuss information and to share generic issues such as queries regarding

statistical analysis, word limits, plagiarism and structure. They also improved my team

working ability.

However, the full group meetings and the one to one meetings with Ian Lawson, were the

most useful. They gave me a fantastic opportunity to meet new people who were also

undertaking a palaeo-dissertation and to discuss any queries with my tutor. I found them

useful as Ian Lawson sometimes suggested ideas to other students in the group, which I

could also use in my study. They were also useful as my tutor was supportive and motivated

me when problems occurred.

The only criticism I have with the DSG meetings is regarding the peer group meetings. As I

worked alongside the peer group members in the laboratory, I sometimes felt that extra

meetings were not necessary. This was because we naturally discussed our dissertations and

the progress that we had made. Furthermore, the other students of the peer group were

undertaking a similar dissertation to one another. I therefore felt that I could not make a

great scientific input into their dissertation, but I tried to be supportive at all times.

Overall, I found the DSG meetings a success. By having these meetings, a now feel that I

have the confidence to undertake a scientific investigation with limited support. They not

only provided me with encouragement, but also provided constructive solutions to any

problems that I encountered. I thoroughly enjoyed helping my peers, and hope that I was

supportive to them.

96

10.4. DSG Report Forms

GEOG3600 Dissertation

97

98

99

100

101

102

103

NB Continuous discussions about progress occurred virtually every day before Christmas

due to all three members working in close association in the labs and microscope rooms.

This allowed problems to be addressed and solved quickly.

104

10.5. Interim Report

10.5.1. First Interim Report

The history of human activity at Quidenham Mere, interpreted by ostracod and mollusc

analysis.

INTRODUCTION

Central East Anglia is abnormal for Southern

England in containing a number of natural lake

basins (Lewis, et al., 1991). Bennett, et al., (1990)

documented a complete Holocene sequence in

the calcareous marls at Quidenham Mere,

Norfolk. Recent work at Quidenham Mere has

focused upon fossil pollen, charcoal as well as

biological indicators, such as chironomids and

molluscs (Peglar, 1992). It is reported that

Quidenham Mere underwent a whole

eutrophication event, which started in the Tudor

period and finished in the Victorian period

(Xianoying, et al., 2007). It is argued that Quidenham Mere experienced this phenomenon

due to an extreme input of nutrients from hemp retting, as the Mere was used as a hemp

pit during the Post-Medieval period (Xianoying, et al., 2007). There has been no work;

however, that reports the concentration change of nutrients at Quidenham Mere over this

time span. There is also limited work focussing on ostracods concentration throughout the

sequence. The aim of this literature therefore is to give a greater insight into the cultural

eutrophication process. Adding to this is the use of ostracods and nutrient concentration as

a palaeoenvironmental indicator.

Map of East Anglia showing the

location of Quidenham Mere (QM)

(Peglar, 1992).

105

OVERVIEW OF CORE THEMES

2.1 Eutrophication

The process of eutrophication was first documented by the work of Brandt (1901). Brant

(1901) established a relationship between the concentration of plankton and the

concentration of nitrogen in the freshwater lakes of Germany (Smith, 1998). Naumann

(1919) who classified waters in Sweden depending on their nutrient content (Martin and

Teubner, 2010) advanced this idea. Cultural eutrophication however was first acknowledged

as a phenomenon post World War 2, due to the increased need of fertilizers and pesticides

(Moss, et al., 1997; Xiaying et al., 2007). It is documented that cultural eutrophication can

cause severe water problems such as anoxic conditions and turbid waters (Martin and

Teubner, 2010; Holden, 2008). There is controversy however over whether cultural

eutrophication is a recent event or whether it has occurred in the past, yet been restored

(Xiaying, et al., 2007). It is clear that there is a lack of data in the historical record of cultural

eutrophication. There is also limited literature that explores the influence of human activity

on the eutrophication phenomenon under natural background (Xiaying, et al., 2007).

2.2 Lake deposits

Lake deposits have been used extensively for the reconstruction of past environments. In

recent years, however there have been many advances and developments in the techniques

required to analyse and date lake deposits (Anderson, et al., 2007). In comparison to other

types of deposits, lake sediments commonly provide continuous stratigraphic records (West,

1991). This is because they accumulate for great periods undisturbed by erosion and

weathering (Jenkin, et al., 1941; Anderson, et al., 2007). Lake sediments can therefore

provide a record of the biological history of lakes and the environmental conditions in which

sedimentation occurred.

106

2.2 Micropaleontology

Micropaleontology is a branch of science concerned with the study of microfossils in order

to reconstruct paleoenvironments (Martin, 2000). A particular fossil commonly used in

micropaleontology are ostracods. Ostracods are marine and freshwater microscopic

bivalved crustaceans that are frequently fossilized in sediments from the Cambrian period

(Athersuch, et al., 1989; Siveter, et al., 2010). These fossils were first analysed by the work

of O. F. Müller in 1776 (Griffiths and Holmes, 2000). Ostracods have remained a lively topic

and have grown in complexity with an advance of technology. It was the work of Jones

(1850) however who documented the great biostratigraphical significance of ostracods

(Griffiths and Holmes, 2000). Subsequent work has revealed that ostracod fossils are an

ideal factor for studying paleoenvironments (Evans and Griffiths, 1993). An advantage of

ostracods in the field of palaeoecology is that they are very numerous (Bignot, 1982; Butlin

and Menozzi, 2000). Ostracods inhibit practically every aquatic environment, even physically

demanding environments such as temporary pools, hypersaline lakes and hot springs

(Athersuch et al., 1989; Henderson, 1990). An additional advantage is that they exhibit

wonderful patterns of difference within and between the species (Butlin and Menozzi,

2000). Changes in salinity, temperature, hydrogen ion concentration (pH), oxygen

concentration, depth, substrate and food supply of the surrounding environment can

therefore be determined (Athersuch, et al., 1989). The most important advantage however

is that ostracods are preserved in situ in a long and complete fossil record (Butlin and

Menozzi, 2000). This allows an in depth analysis over a vast period of years.

2.3 Conclusion

A great body of literature has accumulated in recent years on the study of palaeontology in

Central East Anglia (Bennett, 1990; Lewis, et al., 1991). It is clear that most sites, which

contain a complete Holocene record in East Anglia, have only been studied palynologically

and not by any other means. There is therefore considerable scope for more

palaeoecological and paleolimnological examination in this region. The analysis of ostracods

and cations (K+ and Na+) in the sequence will therefore provide greater knowledge of the

eutrophication event at Quidenham Mere.

107

AIMS AND OBJECTIVES

3.1. Aims

1) To analyse the organic and carbon content of the core.

2) To analyse the magnetic minerals in the core and identify the depositional history of

area.

3) To reconstruct past nutrient levels of the last 600 years at Quidenham Mere.

4) To construct a high resolution record of the ostracods preserved in the sequence

focusing on the eutrophication event, which started in the Tudor period and finished

in the Victorian.

3.2. Objectives

1) To perform loss-on-ignition on the core at 450 °C and 950°C to produce an organic

and carbonate record to establish the organic and carbon content of the sediment.

2) To perform magnetic susceptibility on the core to identify any soil erosion events at

Quidenham Mere.

3) To describe the core using the Troels-smith method to identify the depositional

history of Quidenham Mere.

4) To carry out a geochemistry analysis of the elements K and Na in order to show the

impact of the eutrophication event, and whether it has been restored.

5) To use this nutrient analysis to determine where on the sequence to carry out a high

resolution ostracod analysis.

6) To use the nutrient and ostracod analysis to interfere anthropogenic effects on the

landscape.

METHODOLOGY

4.1. Magnetic susceptibility (completed 25/10/2010)

Magnetic susceptibility was performed to measure the quantity of magnetic minerals in the

sample in order to identify any soil erosion event that occurred at Quidenham Mere

(Schaetzl and Anderson, 2005). Recordings using a magnetic susceptibility meter were taken

108

every 2 centimetres along the core. This stratified sampling method provided a sufficient

amount of data to draw a valid conclusion from.

4.2. Geochemistry analysis

To record the levels of Na and K throughout the core, an analysis will be performed using an

Atomic Absorption Spectrometer (AAS) (Sperling, et al., 1999; Boyle, 2001). The pH

throughout the core will first be measured in order to decide an appropriate method for

cation extraction. The pH will be recorded at 100cm intervals throughout the core using the

electrometric method. In order to perform the electrometric method, a 20 g sample will be

mixed with 50 ml of deionised water and allowed to equilibrate (Sarkar, 2005). An electrode

will then be inserted into the mixture and the pH will be read directly of the meter

(Cheswoth, 2008). If the sample has a pH > 5, ammonium acetate will be used for the cation

extraction (Gillman, 1979). It the sample has a pH < 5, ammonium chloride will be used for

the cation extraction (Narin, et al., 2000). This method has been documented as successful

in previous literature. To prepare the samples for the atomic absorption spectrophotometer

(AAS), 5g of air-dried soil will be weighed and carefully placed into a clean, dry shaking

bottle. The samples shall then be mixed with either 125 mL of 1M ammonium acetate or 40

ml of 1M ammonium chloride depending on the pH of the sample (Narin, et al., 2000). The

solutions shall than be placed on a shaker for 1 hour, to ensure the samples are thoroughly

mixed. The final preparation step is to filter the solutions through Whatman number 1 filter

paper, ensuring to reject the first 5 – 10 mL. Whatman number 1 filter paper will be used to

achieve accurate results (Whatman, 2009). The samples will then be analysed using the AAS.

A standard curve will then be constructed to calculate the concentration values. This is a

sufficient method for interfering past nutrient levels and will provide valuable information

on past processes (Boyle, 2001).

4.3. Ostracod analysis

The sub-sampling of core sediments requires careful thought (De Deckker and Forester

1988; Griffiths and Holmes 2000). The interval and thickness of each sample depends on a

variety of factors including the concentration of ostracods in the sediment and the

109

regularity of the sampling method. Due to the variation of ostracod concentration

throughout the core, there are no documented guidelines for the weight or volume of

sediment required. A pilot study will therefore be performed to produce a species

acquisition curve (Henderson and Walker, 1986). A small subsample of sediment will be

taken and the number of species present will be recorded. The sample size will then be

increased in small additions until the plot for number of species reaches asymptote

(Griffiths and Holmes, 2000). It will then be possible to estimate the mass of sediment

required to achieve full species representation.

It is extremely difficult to pick ostracod valves from raw sediment samples. Pre-treatment is

therefore required to carefully break down the sediment into individual grains (Griffiths and

Holmes, 2000). The sediments shall then be prepared for analysis using the standard

hydrogen peroxide method. This method was chosen as it has been successful in previous

studies. (De Deckker, 1982; Griffiths, 1995). Samples will be taken every ten centimetres

throughout the core and every 1 centimetre where the eutrophication event occurred. This

will provide a high-resolution analysis. The lake sediment samples shall then be digested in

c. 10% hydrogen peroxide and placed in a fume cupboard overnight in order to digest. To

extract the ostracods, the samples shall be passed through a 125 micron sieve and

thoroughly washed with distilled water to remove any chemical residue. Even though

hydrogen peroxide is frequently used for ostracod analysis, there are several pieces of

literature which argue that hydrogen peroxide can destroy fragile shells (Sohn, 1961;

Hodgkinson, 1991; Slipper, 1996). Care shall be taken therefore to produce accurate results.

4.4. Loss on ignition (LOI)

LOI will be performed to calculate the total organic matter and the total organic carbon of

the core. To calculate the total organic matter, samples will be taken every centimetre along

the core. The weight of the crucibles will then be measured (Wc) and filled 2/3 full of

sediment. The crucibles will then be re-weighed (Wcs) and positioned on a metal tray and

placed in a muffle furnace at 450°C. After 24 hours, the temperature of the furnace will be

decreased to 50°C for safety reasons. The samples will then be transferred to a desiccator.

110

The weight of the crucible and ignited soil will be weighed (Wi). LOI will then be calculated

using the following formula: % LOI = 100 x (Wd -Wi)/(Wd-Wc). This process will then be

repeated at 900°C to calculate the total organic carbon of the core. This method is the

standard procedure used to determine LOI (Hesse, 1971). It will therefore provide reliable

results.

RESULTS

5.1. Magnetic susceptibility results

The magnetic susceptibility analyse did not show any significant input of the magnetic

minerals throughout the core. This implies that there were no important soil erosion events

during the Tudor period until the Victorian period at Quidenham Mere. This outcome

corresponds with my predictions.

TIMETABLE

6.1. Timetable of important dates

111

Date Event/Deadline Action

Friday 5th

November

2010

Meeting with Ian Lawson

(11:00 pm)

Learn how to identify ostracods

in the sample.

Monday 7th

November

Lab work: Description of the

core

(i) Description of the core using

the terminology of Troels-Smith.

(ii) Book AAS induction with Jon

Corr.

Tuesday 8th

November

Lab work: LOI

DSG meeting

(i)Preparation of sample to

determine organic content of

core.

Wednesday 9th

November

Lab work: LOI (i)Weighing of samples

(ii) Preparation of samples to

determine carbon content of

core.

Thursday 10th

November

Lab work: LOI Weighing of samples.

Friday 11th

November

Troels-smith Write up of Troels-smith

sediment description.

Monday 13th –

Tuesday 30th

November

Lab work: Ostracods and AAS Analysis of ostracods and

nutrient content of the samples.

Wednesday 1st

-15th

December

Write up of dissertation Introduction and Literature

Review

Thursday 16th

– Friday 31st

December

Write up of dissertation Methods write up.

Monday 1st

December -

Saturday 15th

January

Write up of dissertation Analysis and start of discussion

section

112

Sunday 16th

January –

Wednesday 2nd

February

Second Interim Report 1500 words including finalized

aims and objectives, methods of

analysis and key research

findings.

Thursday 3rd

February –

Monday 28th

February

Write up of dissertation Write up of Discussion and

Conclusion sections

Tuesday 1

March –

Wednesday

16th March

Editing Overall research. Is discussion

logical?

Wednesday 16

March 2011

Final deadline (i)Hand in of dissertation (hard

copy and CD version) including

DSG forms, two interim reports,

reflective, commentary and risk

assessment forms.

(ii)Hand in of Student Evaluation

on Dissertation and Mentor

Evaluation form.

6.2. Timetable of DSG meetings

Tuesday 9th November Discuss any problems of LOI laboratory work.

Tuesday 16th November Discuss any problems of Troels-Smith analysis/ write up.

Tuesday 23rd November Discuss any problems of ostracod analysis or results from

AAS.

Tuesday 30th November Highlight any problems of ostracod analysis or results

from AAS.

Tuesday 7th December Talk with group about the content of the introduction

and literature review sections of the dissertation.

Tuesday 11th January Discuss any problems found in the write up of the

method, analysis and discussion sections of the

dissertation.

113

Tuesday 18th January Talk about second Interim Report.

Tuesday 25th January Discuss any problems found in the second Interim Report

and any ideas for discussion section.

Tuesday 1 February Highlight any problems in the discussion section.

Tuesday 8 February Highlight any problems in the discussion section.

Tuesday 15 February Highlight any problems in the discussion section.

Tuesday 22 February Highlight any problems in the discussion section.

Tuesday 1st March Discuss how an appropriate layout for the dissertation

and any final problems with dissertation.

Tuesday 8th March Discuss any final problems with dissertation

Tuesday 15th March Review how to submit the dissertation.

References

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ATHERSUCH, J., HORNE, D. J., and WHITTAKER, J. E. 1989. Marine and Brackish Water

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BENNETT, K. D., SIMONSON, W.D., and PEGLAR, S. M. 1990. Fire and man in the post-glacial

woodlands of eatern England. Journal of Archaeological Science. 17, pp. 237 – 253

BIGNOT, G. 1982. Elements of micropalaeontology: microfossils, their geological and

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BOYLE, J. F. 2001. Inorganic geochemical methods in palaeolimnology. In: W. M. Last, and J.

P. Smol, eds. Tracking environmental Change using Lake Sediments, Volume 2, Physical and

Geochemical Methods. Dordrecht: Kluwer Academic Publishers, pp. 83 – 141

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BUTLIN, K. R., and MENOZZI, P. 2000. Open questions in evolutionary ecology: do ostracods

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De DECKKER, P., and FORESTER, R. M. 1988. The use of ostracods to reconstruct

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EVANS, J. G., and GRIFFITHS, H. I. 1993. Holocene mollusc and ostracods sequences: their

potential for examining short-time scale evolution. In: LEES, D.R. and D.Walker, eds.

Evolutionary Patterns and Processes. London: Academic Press pp. 125–137

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GRIFFITHS, H. I., and HOLMES, J. A. 2000. Non-Marine Ostracods and Quaternary

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blackwater stream Tarumazinho. Journal of Tropical Ecology. 2, pp. 1-17

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Edition. Essex: Harlow

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LEWIS, S. G., WHITEMAN, C. A. and BRIDGLAND, D. R. 1991. Central East Anglia and the Fen Basin: Field Guide. London: Quaternary Research.

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environmental Geology. New York: Springer.

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enriched Shallow Lakes. London: Springer.

NARNIN, I, SOYLAK, M, ELÇI, L., and DOGAN, M. 2000. Determination of trace metal ions by

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PEGLAR, S. M. 1992. Mid-and late-Holocene vegetation history of Quidenham Mere,

Norfolk, UK interpreted using recurrent groups of taxa. Vegetation History and

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117

10.5.2. Second Interim Report

The effect of human activity at Quidenham Mere since the medieval period, interpreted

by mollusc and nutrient data.

1.0 AIMS AND OBJECTIVES

1.1. Aims

5) To produce sediment lithology diagram and a sediment composition diagram of the

core.

6) To produce a magnetic susceptibility graph of the core.

7) To reconstruct past nutrient levels of the last 600 years at Quidenham Mere.

8) To construct a high resolution record of the molluscs preserved in the sequence.

1.2. Objectives

7) To perform loss-on-ignition on the core at 450°C and 950°C to produce an organic

and carbonate record to establish the organic and carbon content of the sediment.

8) To describe the core using the Troels-Smith (1955) method in order to identify the

depositional history of Quidenham Mere.

9) To perform a magnetic susceptibility analysis on the core to identify whether

eutrophication was caused by human activity or by soil erosion.

10) To perform a geochemistry analysis of the elements K and Na in order to show the

positioning and impact of eutrophication at Quidenham Mere.

11) To examine the high-resolution mollusc record to decipher the ecological impact of

eutrophication at Quidenham Mere.

2.0. RESULTS

2.1. Sediment Analysis

The sediment lithology of the core was analysed using the system of Troels-Smith (1955).

The organic content and carbonate content of the core was calculated from loss-on-ignition

at 450°C and 950°C, respectively, following the standard procedure of Hesse (1971).

2.1a. Sediment Lithology

The bottom of core QUID1 is composed of calcium carbonate. Particulate testarum

molluscorum become present at 802 cm and remain throughout the core. The calcareous

118

marl varies in stratification from values 1 – 3 and undergoes a rapid transition into peat at

360 cm, which remains to 125 cm. The base of the peat is very dark brown/black and is

composed of sphagnum leaves. In the middle part of this section, the peat becomes lighter,

coarser and contains fragments of herbaceous plants and wood segments such as Betula.

The peat continues becoming lighter above this section and herbaceous plants and wood

segments dominate. The peat then gradually changes to a dark brown herbaceous peat at

approximately 161 cm.

119

2.1b Sediment composition

Figure 2. A comparison between Peglar’s (1993) sediment composition diagram (434 – 1240

cm) and the QUID1 sediment composition diagram (125-830cm). The coloured lines indicate

where the organic and carbonate component correspond.

There is a similarity between the trends of the organic and carbonate content throughout

the two cores, however the major features occur at different depths. For example, the

organic content of the QUID1 core first peaks at 750 cm to approximately 37%, while the

organic content of Peglar’s (1993) core peaks at 790cm to approximately 37%. Furthermore,

the carbonate content of the QUID1 core declines to 670 cm, while Peglar (1993) shows that

it declines to 710 cm. Peglar (1993) also shows a slight decline in organic content at 500 cm

followed by a rise in the carbonate content. This study also found this trend, however the

organic content of QUID1 declines at 420 cm. It is therefore clear that QUID1 differs to

Peglar’s (1993) sediment composition by 50-80 cm.

120

2.3. Magnetic Susceptibility

Figure 3. The input of magnetic susceptibly elements in QUID1. The magnetic susceptibility

results from QUID1 reveal a general increase of magnetic susceptible elements from 830 cm

to 0 cm. The results also show that the core is rich in diamagnetic substances (Dearing,

1999). This finding is in agreement with the QUID1 sediment analysis. On closer analysis, the

results reveal a relatively steady input of magnetic susceptible elements from 830 cm to 690

cm, with minor fluctuations. Following this, the rate of input rapidly increases between 690

and 530 cm indicating a period of soil erosion. Following this, the input of magnetic

susceptible elements becomes relatively steady, with minor fluctuations, between 530 cm

and 0 cm.

121

2.4. Nutrient Analysis

Figure 4. The geochemistry of Quidenham Mere from the Medieval Period to the present,

focussing upon the concentration of sodium and potassium (NB values <0 have been

recorded as 0. This is because the concentration < the blank value).

Two peaks are prominent in the concentration of sodium and potassium. From the base of

QUID1, the concentration of potassium is approximately 1 mg/kg. The concentration of

potassium peaks at 745 cm (23 mg/kg) before gradually decline to 0 mg/kg. This variable

remains at 0 mg/kg to 385 cm, before rapidly rises to 0.5 mg/kg. Following a rapid decline in

the concentration of potassium, another peak is prominent at 345 cm (58 mg/kg). The

concentration of potassium then quickly declines and fluctuates around 2 mg/kg between

325 cm – 125 cm.

The concentration of sodium throughout QUID1 is greater than that of potassium, yet

follows a similar pattern. From the base of QUID1, the concentration of sodium is

approximately 6 mg/kg until it gradually peaks at 765 cm to 33 mg/kg. This variable then

relatively rapidly declines and fluctuates greatly between 0 mg/kg L and 11 mg/kg until 455

cm. At 455 cm the concentration of sodium sharply rises to 77 mg/kg, before declining

rapidly to 12 mg/kg. This is followed by another rapid increase at 395 cm to 90 mg/kg.

Following this rise, the concentration of sodium very quickly declines and greatly fluctuates

around 4 mg/kg throughout the rest of the core.

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2.5. Mollusc analysis

Figure 5. The change in abundance of molluscs in the sediments of Quidenham Mere. Two

sharp peaks are prominent, one at 745 cm – 765 cm and the second at 345 cm and 385 cm.

Following these peaks, the abundance of molluscs rapidly declines to a value similar to that

prior to the peak. The abundance of molluscs at 125 cm < the abundance of molluscs at 830

cm.

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2.6. Statistical Analysis

Variable Potassium Sodium Organic Material Magnetic

susceptibility

Potassium Not correlated

(P = 0.758)

Slightly

Positively

correlated (PC =

0.476, P = 0.000)

a) 125-600 cm:

not correlated (p

= 0.208).

b) 600 – 830 cm:

not correlated (P

= 0.136).

Sodium Not correlated (P

= 0.758)

Not correlated (P

= 0.474)

a) 125-600 cm:

not correlated (P

= 0.121)

b) 600 – 830 cm

not correlated (P

= 0.384)

Organic Material Slightly

Positively

correlated (PC =

0.476, P = 0.000)

Not correlated

(P = 0.474)

a) 125-600 cm:

not correlated (P

= 0.690)

B) 600 – 830 cm

not correlated (P

= 0.547).

Magnetic

susceptibility

a) 125-600 cm:

not correlated (p

= 0.208).

b) 600 – 830 cm:

not correlated (P

= 0.136).

a) 125-600 cm:

not correlated (P

= 0.121)

b) 600 – 830 cm

not correlated (P

= 0.384)

a) 125-600 cm:

not correlated (P

= 0.690)

B) 600 – 830 cm

not correlated (P

= 0.547).

Table 1. A summary of statistical analysis performed on the eutrophication indicators of

Quidenham Mere (PC = Pearson's correlation). When p < 0.05, there is a statistical

correlation between the two variables.

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Mollusc /

eutrophication

indicator

Bithynia

tentaculata

Gyraulus

sp.

Lymnaea

sp.

Valvata sp. Pisidium sp.

Potassium Positively

correlated

(PC = 0.447,

P = 0.000)

Positively

correlated

(PC = 0.315,

P = 0.008)

Positively

correlated

(PC = 0.292,

P = 0.014)

Positively

correlated

(PC =

0.283, P =

0.017)

Positively

correlated

(PC =0.315,

P = 0.007)

Organic matter Positively

correlated

(PC = 0.507,

P = 0.000)

Positively

correlated

(PC = 0.478,

P = 0.000)

Positively

correlated

(PC = 0.432,

P = 0.000)

Positively

correlated

(PC =

0.508, P =

0.000)

Positively

correlated

(PC = 0.479,

P = 0.000)

Table 2. A summary of the statistical mollusc data-set of Quidenham Mere (PC = pearson's

correlation). If p < 0.05, the two variables are statistical correlated with one another.

3.0 DISCUSSION

3.1. Identifying eutrophication

In order to determine the process of eutrophication at Quidenham Mere, the nutrient

content, and the organic matter content were analysed (Grigorovich, et al., 2005). This

multi-proxy method is ideal as can abolish misleading information provided by single-proxy

studies (Birks, 2006: Xianoying, et al., 2007). The potassium content was used as an

indicator of eutrophication as the work of Leentvaar (1980) documents that potassium

increases during this phenomenon. The organic matter content is also an indicator of

eutrophication as the work of Ongley (2006) and Ortega, et al., (2006) reveals that the

organic matter increases during eutrophication. The work of Rabalais (2010) further

supports this idea by documenting that the increase of organic matter during eutrophication

is due to soil erosion, natural weathering, or human activity. The sodium content however

was used in this investigation as an indicator of the onset of the eutrophication. This is

125

because the work of Livingstone and Boykin (1962) documents that eutrophication is

directly related to the ionic content of the water. This is further advanced by the work of

NAS (1969) which reveals that sodium promotes eutrophication.

The nutrient and organic matter results agree with previous literature. The data shows that

there is a significant statistical positive correlation between the organic content variable and

the potassium concentration variable. This idea coincides with the work of Ongely (1996).

The results also show that there is no significant statistical correlation between the organic

matter variable and the sodium concentration variable. This idea coincides with the work of

Livingstone and Boykin (1962), NAS (1969) and Ongley (2006).

It is therefore clear that two episodes of eutrophication occurred at Quidenham Mere

between the Medieval Period and the present day. The first episode of eutrophication

occurred at approximately 775- 675 cm (Medieval-Post Medieval period) .This idea coincides

with the work of Xiaoying, et al., (2007). The second episode of eutrophication occurred at

approximately 400 – 300 cm (the last 200 years). No previous literature has focussed upon

the 450 – 0 cm section of the profile before, therefore the latter is a new finding.

3.2 What was the cause of the Medieval-Post Medieval (M-PM) eutrophication event at

Quidenham Mere?

Magnetic susceptibility measures the quantity of magnetic susceptible element in a sample

and is a good proxy for soil erosion (Hirons and Thompson, 1986; Nowaczyk, 2001). By

analysing the magnetic susceptibility results for Quidenham Mere, we are able to identify

the cause of the eutrophication events.

The data shows that the negative correlation between the organic/potassium variable and

the magnetic susceptibility variable is not statistically significant for the M-PM

eutrophication event. Furthermore, the positive correlation between the sodium variable

and the magnetic susceptibility variable is not statistically significant. It is therefore clear

that soil erosion was not the main causes of this eutrophication event. Consequently,

anthropogenic activities are a legitimate r to explain the M-PM eutrophication event. This

126

idea corresponds with the work of Xiaoying, et al., (2007) which documents that the M-PM

eutrophication event occurred due to the cultivation of Cannabis sativa within the Mere.

This work has been advanced by Yang (2010) which documents that the region surrounding

Quidenham Mere has been contaminated over the last thousand years due to hemp-retting.

Furthermore the work of Peglar (1993) reveals that Cannabis sativa increased during the M-

PM period (Figure 6). Hemp retting would have therefore caused the Mere to become highly

eutrophic due to an increase of nutrients and organic matter (Xiaoying, et al., 2007).

Figure 6. Peglar’s (1993) pollen stratigraphy of Quidenham Mere. There is a rapid increase in

Cannabis sativa during the Medieval period (QM–9b). After a gentle decline of Cannabis

sativa at the end of the subzone QM-9b, Cannabis sativa increases rapidly to a maximum of

94% during the Post Medieval (QM-9c).

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3.3 What was the cause of the most recent eutrophication event at Quidenham Mere?

The data shows that the positive correlation between the organic/potassium/sodium

variable and the magnetic susceptibility variable are not statistically significant for the most

recent eutrophication event. Quidenham Mere therefore became eutrophic at this time due

to anthropogenic activities and not soil erosion. This idea coincides with the work of Peglar

(1993) which documents that the Mere was used as parkland during the last 200 years.

Peglar (1993) also explains that the high charcoal concentration during this period was due

to the development and maintenance of the parkland. It therefore seems logical that the

development of the parkland, by forest clearing and fertilization, caused an excess of

nutrients and organic matter to enter the water system, thus causing the Mere to become

eutrophic. Furthermore, the burning of the vegetation would have released nitrate into the

atmosphere, which would have entered the water system and caused the Mere to become

eutrophic (Moss, 2008).

3.4. What effect did eutrophication at Quidenham Mere have upon the abundance of

molluscs?

a) Bithynia tentaculata

The results show that there is a significant statistical positive correlation between the

Bithynia tentaculata variable and potassium/organic content variable. It is therefore clear

that the eutrophication process initially caused an increase of Bithynia tentaculata. This is

due to the species ability to filter feed in eutrophic and human influenced waters

(Brendelberger and Jiirgens, 1993).

However, it is clear from the dataset that the population of Bithynia tentaculata declined

following the excessive input of nutrients. This was due to low DO and the toxic by-products

of hemp retting, such as hydrogen sulphide (Xiaoying, et al., 2007). This finding is in

agreement with the work of Xiaoying, et al., (2007) who found a marked decrease in

Bithynia tentaculata during the M-PM eutrophication event of Quidenham Mere. This idea

also concurs with the work of Richter (2001) which documents that low DO can cause a

decline in the Bithynia tentaculata population. Furthermore, the work of Kermey (1999)

128

documents that Bithynia tentaculata are not common in oxygen-depleted waters. It is

therefore clear that the population of Bithynia tentaculata at Quidenham Mere declined

due to (i) the mollusc being gill breathing (ii) the inability of the mollusc to migrate from its

microhabitat after rapid environmental change (Hann, 2005).

b) Gyraulus sp.

The results show that there is a significant statistical positive correlation between the

Gyraulus sp. variable and the potassium/organic variable. It is therefore clear that the

eutrophication process initially caused an increase in the Gyraulus population. This idea

coincides with the work of Lysne and Clark (2009) which documents that Gyraulus are

tolerant of eutrophic waters and high nutrient levels. The Gyraulus population then

experienced a rapid decline due to species’ intolerance to hydrogen sulphide (Xiaoying, et

al., 2007).

c) Lymnaea sp.

There is a significant statistical positive correlation between the Lymnaea sp. variable and

the potassium/organic variable. It is clear that the eutrophication process initially caused an

increase in the Lymnaea population. This is due to the snail’s ability to take in oxygen

through its pneumostome (Clifford, 1991) (Figure 7). Furthermore, the work of Lodge and

Kelly (1985) documents that Lymnaea undergoes a phonological plasticity in order to

respond to periods of low dissolved oxygen. Following this increase, the Lymnaea

population experienced a quick decline due to species’ intolerance to hydrogen sulphide

(Xiaoying, et al., 2007).

Figure 7. Diagram of a Lymnaea snail

with the main features labelled. In

order to survive in periods of low DO,

the snail hangs suspended from the

upper surface of the water. The snail

subsequently takes in oxygen by

opening its pneumostome (Clifford,

1991).

129

d) Valvata sp.

There is a significant statistical positive correlation between the Valvata sp. variable and the

potassium/organic variable. It is clear that the eutrophication process initially caused an

increase in the Valvata population. This finding coincides with the literature of Lodge and

Kelly (1985) which documents that Valvata can survive periods of eutrophication due to

behavioural and physiological plasticity. Furthermore, the work of Grigorovich, et al., (2005)

documents that Valvata is an effective competitor in eutrophic water as it can feed on

suspended particles. Following this increase, the Valvata population experienced a rapid

decline due to species’ intolerance to hydrogen sulphide (Xiaoying, et al., 2007).

a) Pisidium sp.

The results show that there is a significant statistical positive correlation between the

Pisidium sp. variable and the potassium/organic variable. It is clear that the eutrophication

process initially caused an increase in the Pisidium population. The data set however clearly

shows that the abundance of Pisidium only slightly declined following the excessive input of

nutrients. This finding agrees with the work of Caldwell (1975) which reports that bivalve

molluscs are more resistant to hydrogen sulphide than gastropod molluscs.

4. Significance of main findings

In recent years, a debate has arisen about whether cultural eutrophication is a modern

event, or whether it has occurred in the past, yet been restored (Xiaoying, et al., 2007).

There is also controversy over the extent to which human activity influences the process of

eutrophication. The findings from this literature will therefore add to previous knowledge in

order to further our understanding of this topic.

In addition to this, the study site is of great importance as there is limited work focussing

upon Quidenham Mere. There has been no work, for example, that reports the

concentration change of nutrients at Quidenham Mere since the medieval Period.

Furthermore, the work of Xiaoying, et al., (2007) lacks details of which species of molluscs

where effected by the M-PM eutrophication event. Adding to this, there is no literature

documenting the most recent eutrophication event at Quidenham Mere. This literature will

130

therefore give a greater insight into the cultural eutrophication process and provides a basis

for further study of the recent eutrophication event at Quidenham Mere.

5. APPENDIX

5.1 Outstanding work

In order to produce a thorough and scientific dissertation more work is required. For

example, a Troels-Smith diagram using the Psimpoll software is required. I have also

organised a meeting this week with Rachel Gasior to learn how to report less than figures

for the geochemistry analysis. Furthermore, a greater body of literature must be read in

order to demonstrate a detailed understanding of the main themes.

5.2 Dissertation Headings

List of figures

List of Tables

Acknowledgment

Abstract

1. Introduction

2. Aims and Objectives

2.1 Aims

2.2 Objectives

3. Overview of core themes

3.1 Eutrophication

3.2 Lake deposits

3.3 Micropalaeontology

4. Study Area

4.1 Site location and description

4.2 Site Selection

4.3 Limitations of site chosen

5. Methodology

5.1 Sediment description and stratigraphy

5.3 Sediment sampling

5.4 Magnetic susceptibility

5.5 Geochemistry

5.6. Mollusc identification

5.7. Limitations of methods

131

6. Results

6.2 Stratigraphy

6.3 Magnetic susceptibility

6.4 Nutrient Analysis

6.5 Mollusc analysis

7. Discussion

7.1 Identify eutrophication

7.2. What was the cause of the eutrophication events

7.3. What effect did the eutrophication events have upon the abundance of

molluscs?

8. Conclusion

8.1 Summary of main finding

8.2 Significance of main findings

8.3 Scope for further study

9. Bibliography

10. Appendix.

10.1 Risk assessment form

10.2 DSG Report logs

10.3 DSG Reflective log

10.4 Interim Report 1 and 2

5.3 References

BIRKS, H. H. and BIRKS, H. J. B. 2006. Multi-proxy studies in Palaeolimnology. Veget. Hist.

Archaeobot. 15, pp. 235 -251.

BIRKS, H. H. and BIRKS, H. J. B. 1980. Quaternary Palaeoecology. Edward Arnold, London

BRENDELBERGER, H. and JIIRGENS, S. 1993. Suspension feeding in Bithynia tentaculata

(Prosobranchia, Bithyniidae), as affected by body size, food and temperature. Oecologia. 94,

pp. 36-42.

CALDWELL, R. S. 1975 Hydrogen sulphide effects on selected larval and adult marine

invertebrate. Water Resour., Research Institut. 31, p. 27.

CLIFFORD, H. F. 1991. Aquatic invertebrates of Alberta: an illustrated guide. Alberta:The

University of Alberta Press.

132

DEARING, J. 1999, Magnetic susceptibility. In: WALDEN, J., OLDFIELD, F. and SMITH, J. P. eds.

Environmental magnetism: a practical guide. Technical Guide, No. 6. London: Quaternary

Research Association. pp. 35 – 62

GRIGOROVICH, I. A., MILLS, E. L., RICHARDS, C. B., BRENEMAN, D. and CIBOROWSKI, J. J. H.

2005. European Valve Snail Valvata piscinalis (Müller) in the Laurentian Great Lakes Basin.

Journal of Great Lakes Research. 31, pp. 135 – 143.

HANN, T. 2005. Respiration rates in Bithynia Tentaculata (l.) (gastropoda: bithyniidae) in

response to acclimation temperature and acute temperature change. Journal of Molluscan

Studies. 71, pp. 127–131.

HESSE, P. R. 1971. A textbook of Soil Chemistry Analysis. London: William Clower and Sons.

HIRONS, K. R. and THOMPSON, R. 1986. Palaeoenvironmental application of magnetic

measurements from inter-drumlin hollow lakes sediments near Dunganon, Co. Tyrone,

Northern Ireland. Boreas. 15(2), pp. 117 – 135.

HORNUNG, M. and LANGAN, S. J. 1999. Nitrogen deposition: sources, impacts and

responses in natural and semi-natural ecosystems. In: S. J. LANGAN, ed. The impact of

Nitrogen Deposition on Natural Semi-Natural Ecosystems. Netherland: Kluwer Academic

Publishers, pp. 1 – 14.

KERMEY, M. 1999. Atlas of the Land and Freshwater Molluscs of Britain and Ireland. Essex:

Harley Books.

LEENTVAAR, P. 1980. Eutrophication, nature management and the role of potassium. Aquatic

Ecology. 14(1-2), pp. 22-29.

LIVINGSTONE, D. A. and BOYKIN, J. C. 1962. Vertical distribution of phosphorous in Linsley

Pond Mud. Limnol. Oceanogr. 7, pp. 57-62.

LODGE, D. M. and KELLY P. 1985. Habitat disturbance and the stability of freshwater

gastropod populations. Oecologia. 68, pp. 111-117.

133

LSYNE, S. J. and CLARK, W. H. 2009. Mollusc Survey of the Lower Bruneau River, Owyhee

County, Idaho, U.S.A. American Malacological Bulletin. 27(1/2), pp. 167-172.

MOSS, B. 2008. Ecology of fresh waters. Man and Medium, Past to Future: Third edition.

Oxford: Blackwell.

NATIONAL ACADEMY OF SCIENCES. 1962. Eutrophication: causes, consequences, correctives;

proceedings of a symposium. Washington: Printing and Publishing Office National Academy

of Sciences.

NOWACZYK, N. R. 2001. Logging of magnetic susceptibility. In: W. M. Last, and J. P. Smol,

eds. Tracking environmental Change using Lake Sediments, Volume 1, Basin Analysis, Coring

and Chronological Techniques. Dordrecht: Kluwer Academic Publishers, pp. 155 - 162 .

ONGLEY, E. D. 1996. Control of water pollution from agriculture – FAO of the United

Nations, FAO irrigation and drainage paper 55. Rome.

ORTEGA, B., CABALLERO, M., LOZANO, S., VILACLARA, G. and RODRÍGUEZ, A. 2006. Rock

magnetic and geochemical proxies for iron mineral diagenesis in a tropical lake: Lago Verde,

Los Tuxtlas, East–Central Mexico. Earth and Planetary Science Letters. 250(3-4), pp. 444-458.

PEGLAR, S. M. 1993. Mid-and late-Holocene vegetation history of Quidenham Mere,

Norfolk, UK interpreted using recurrent groups of taxa. Vegetation History and

Archaeobotany. 2, pp. 15-28.

RABALAIS, N. N. 2010. Eutrophication of Estuarine and Coastal Ecosystems. In: R. MITCHELL,

and J. D. GU, eds. Environmental Microbiology, Second Edition. Hoboken: John Wiley & Sons,

Inc. pp. 115 -137.

RICHTER, T. 2001. Reproductive biology and life history strategy of Bithynia tentaculata

(Linnaeus, 1758) and Bithynia leachii (Sheppard, 1823) [online]. [Accessed 03/01/2011]

Available from: http://edok01.tib.uni-hannover.de/edoks/e002/327030496.pdf.

TROELS-SMITH, J. 1955. Karakterisering af lose jordarter (characterization of unconsolidated

sediments). Damn. Geol. Unders. IV. 3, 1-73.

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XIAOYING, C., SHIJIEM, L. I., QING, S. and JING, X. 2007. Response of cultural Lake

eutrophication to Hemp – retting in Quidenham Mere of England Post-Medieval. Chinese

Geographical Science. 17(1) pp. 69-74.

YANG, H. 2010. Historical mercury contamination in sediments and catchment soils of Diss

Mere, UK. Environmental Pollution. 158(7), pp. 2504-2510.

10.6. Control of Substances Hazardous to Health (COSHH)

The COSHH forms have been included to show that the methods were performed safely.

135

136

137

10.7. Risk assessment forms

The risk assessment for the initial dissertation plan has been enclosed. Unfortunately, the

results from Stow Bedon, Norfolk were not included in this report, as they lacked scientific

significance.

138