Sampling Site

N

Mariager Fjord

Hobro

Mariager

Kattegat

Graphic from http:\\nm.aaa.dk\mfjord

Inner fjord salinity:

12-17‰ at top

18-24‰ at bottom

Outer fjord salinity:

20-25‰

Mariager Catchment

Area: 572 km2

66% agriculture

17% woodland

9% towns

8% lakes

Graphic from http:\\nm.aaa.dk\mfjord1\3 water from catchment

Mariager Fjord - Land Reclamation

Stratification in the inner fjord - when sampling March 2002

2002

Salinity

Oxygen

2002

Graphics from http:\\nm.aaa.dk\mfjord

Oxygen Conditions Now

Depth

Oxygen & Hydrogen Sulphide

Oxygen

Hydrogen Sulphide

Graphic from http:\\nm.aaa.dk\mfjord

Oxygen in 1997

Graphic from http:\\nm.aaa.dk\mfjord

Oxygen in 1997

Graphic from http:\\nm.aaa.dk\mfjord

MOLTEN cores in Mariager Fjord

Two sampling occasions

September 2001 - MF1-5: possibly over-cored

March 2003 - MF6 - 9: intact surface

MF8 - Master Core - dated

Visual assessment showed no major changes down core - all black & smelly

High water content, all levels > 90%

Core CorrelationMF6

R2 = 0,9999

y = -3,2459x + 2005,3

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

0 5 10 15 20 25 30 35

MF8, 210Pb-dated MF6 & MF9 diatom correlated

M F2

0

10

20

30

40

0 20 40 60 80

Depth (cm)

LO

I (%

of

dry

we

igh

t)

Sediment Properties

LOI high (15-30%)

Increase at 20cm

M F9

6,0

6,5

7,0

7,5

8,0

8,5

9,0

9,5

0 10 20 30 40

Depth (cm)

Me

an

pa

rtic

le s

ize

(m

)

No major change in particle size

05

10

15

20

25

0 20 40 60 80 100

BS

i (w

t%)

0,0

0,5

1,0

1,5

2,0

0 20 40 60 80 100

TN

(w

t%)

05

10

15

20

25

0 20 40 60 80 100

TC

(w

t%)

Geochemistry - MF2

TN (1-2%), TC (6-15%) & BSi (10-23%) are all high for coastal sediments

The changes towards core top will disappear when fluxed/corrected for salt concentration

TN

TC

BSi

Pigments - MF6

Comparison between the sitesChlorophyll a Carotenoids

• Mariager Fjord has a very high concentration of pigmentscompared to the other long-core sites

Mariager Fjord, Denmark

0 1000 2000

De

pth

(cm

)

0

10

20

30

0 1000 0 500 1000 15000 500 1000

nmol/gTC

0 500 10000 500 0 500 0 5000 5000 500

210Pb dating

2000

1990

1980

1970

1950

1925

• No shift in community composition, diatoms and dinoflagellates show species change 1890-1925

• Steady increase in chlorophyll a and carotenoids over time

• Dominating pigments in good agreement with monitored algae (diatoms, dinoflagellates) and the ciliate Mesodinium rubrum

• Good preservation, low chl a degradation/chl a ratio

2000

1966

1901

1937

MF9 dominant

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 cm

%

Polykrikos schwartzii

Lingulodiniumpolyedrum

Cysts from 9 taxa found in core MF9

1985 1950 1915

1930

Dinoflagellates

1890

Dinoflagellates

MF9 5-35 %

0

10

20

30

40

50

60

70

0 10 20 30 40cm

%Protoceratiumreticulatum

Spiniferites total.

Protoperidiniumconicum

Finpigget brun (incllyse)

1985 1950 1915 1890

1920

0

5

10

15

20

25

30

35

40

0 0,2 0,4 0,6 0,8 1

cm

pr. cyst

Total brown acritarch1890

1915

1950

1985

1925

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

0 20

ChaRes

0 20 40

ChaVeg

0 20 40 60 80

SkeCos

0 20 40 60 80

CycCho

0 20 40 60

Tha1A

0 20

DitBri

0 20

FraEllA

G

0 20

OpeM

ut

0

PlanDelG

0,0 1,5 3,0 4,5 6,0 7,5

B:P

1890

2001

1920

1965

Diatoms

Excluded taxa & Benthic:Planktonicexcluded

Diatoms

Main Taxa and Reconstructions

1890

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

0

Planot

hidiu

m d

elica

tulum

agg

.

0

Opeph

ora

hors

tiana

0

Opeph

ora

minu

ta

0 20

Opeph

ora

mut

abilis

0

Thalas

siosir

a pr

osch

kinae

0

Tabula

ria fa

scicu

lata

agg.

0 20 40 60

Thalas

siosir

a sp

. 1A

0 20

Thalas

siosir

a cf.

min

ima

0

Cocco

neis

scut

ellum

0 20 40 60 80

Cyclot

ella

choc

tawha

tche

eana

0

Cyclot

ella

men

eghin

iana

0 20

Fragil

aria

ellip

tica

agg.

0

Navicu

la pe

rmin

uta

0 20

Nitzsc

hia cf

. am

erica

na

0

Paulie

lla ta

eniat

a

0 20

Thalas

siosir

a cf.

guil

lardii

0

Thalas

siosir

a wei

ssflo

gii

2.7 3.0 3.3 3.6 3.9

Diatom

-infe

rred

TN

60 100 140 180 220 260

TP

Stable Isotopes - MF9Mariager Delta N15 vs Depth

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14

Delta N15

De

pth

(C

m)

1910

1955

1920

1997

1990

High values No distinct shifts Several possible explanations

Increased fertiliser? Periodic anoxia - more denitrification?

%N in MF9

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

1 2 3 4 7 8 9 10 12 14 16 18 20 24 28 32

Depth

% N

%N from Stable Isotope Analysis

1910

1997

2000

1990

Decrease in %N at core top - denitrification leading to N release as N2 gas? Or will it disappear when fluxed/corrected?

N Fertilizer applied to Mariager Catchment

1935 1955 1975 1995

More fertilizer would lead to heavier N isotopes

1000 tons N/year

Lag?Graphic from http:\\nm.aaa.dk\mfjord

Mariager Delta 13C vs Depth

0

5

10

15

20

25

30

35

40

-23.5 -23 -22.5 -22 -21.5 -21

Delta 13C

De

pth

(c

m)

1890

1920

1975

1993

2000

Fossil fuel burning correction needed - would accentuate increaseProductivity proxy? Increase in anoxic events?

%C

0

2

4

6

8

10

12

14

1 2 3 4 7 8 9 10 12 14 16 18 20 24 28 32 37

Depth

%C

%C from Stable Isotope Analysis

1890

1920

2000

1993

1975

1997

%C decreases at core top - disappear when fluxed/corrected?

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

11 august1987

07 maj 1990 31 januar 1993 28 oktober1995

24 juli 1998 19 april 2001 14 januar 2004

Mariager Areal Productivity

No obvious change

Summation

• Little change seen in TN, TC & BSi

• Good pigment preservation, general agreement with monitoring data, but no indication of community shift

• Largest changes in dinoflagellate species between 1890-1930

• Large change in diatom B:P 1890-1920 Transfer functions hampered by lack of analogues in top, little

agreement between models and no agreement with monitored data

• Delta 15N may show fertilizer signal. Delta 13C signal may reflect increase in anoxia