IMPACTS FROM DISTURBANCES, POLLUTION, AND CLIMATE CHANGE

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IMPACTS FROM DISTURBANCES, POLLUTION, AND CLIMATE

CHANGE

Kaiser part three; ImpactsChapter 14: Disturbances etc

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IMPACTS FROM DISTURBANCES, POLLUTION, AND CLIMATE CHANGE


Chapter 14 overview

1 Introduction

2 Ecological significance of disturbances (Sources, scales, restitution rates, the IDH hypothesis)

3 Measuring the effect of disturbances (Univariate measures, distribution measures, multivariate measures, detection, experimental design, pitfalls)

4 Anthropogenic causes of disturbances (River transport/agriculture, eutrophication, hydropower plants, oil industry, marine mining, chemical vaste)

5 Climate change (Temperature effects, precipitation variation, ocean currents/circulation, multifactor interactions)

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Chapter 14 internal build-up

The problem:The problem: Human activity all over the world is connected with a series of changes in marine ecosystems. Many activities concern exploitation of biological and mineral resources, while other types of impacts concern vaste from industry and agriculture. The resulting changes in marine ecosystems have often been sudden and catastrophal, other times more subtle and not detected before after many years.

The approach:The approach: To assess the ecological significance of human acitivity it is necessary to understand how the marine environment react to ecological disturbances and changes in the environment. It is particularly important to understand the temporal and spatial scales for which the changes are relevant.

The analysis:The analysis: To judge whether ecological changes are responses on manmade disturbances or only general climatic changes, very rigorous experimental designs as well as extensive monitoring are necessary. At the same time, it is important to assess with which statistical power the various types of changes can be detected.

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Chapter 14 executive summary

• Disturbances of marine ecosystems have occurred naturally in all places at all times.

• Responses on disturbances in terms of species diversities appear general and predictable

• Anthropogenic effects must be distinguishable from natural changes (by experimental design)

• The continental shelves are most sensitive to anthopogenic disturbances (fisheries, aquaculture, oil industry, shipping, tourism and pollution)

• Eutrophication caused by agriculture activity have resulted in poisonous algae blooms and mass deaths of marine fauna.

• Resistant pollution (e.g. plastics) have complex and hard-to-detect damage effects

• The consentration of the world population in coast-near areas makes them vulnerable to changes in the ocean level caused by man-made global warming

• Increased amounts of precitation will increase the freshwater runoff and sedimentation in estuarine and coastal systems, and thereby affect density-driven ocean currents (regions of freshwater influence), which in turn change the distribution of plant- and animal societies.

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World population in year 2000 wasca 6 billions. The increase has beenexponential for a long time.

Today the increase is approx. 1.2% p.a.

Year Population(in billions)

2010 6.8

2020 7.6

2030 8.3

2040 8.9

2050 9.4

The increasing world population puts pressure on natural resources, both terrestrial and marine. The world has an increasing demand for protein.

The need for energy has increased dramatically, too, and the use of fossile fuel is believed to be one cause of the rapid global warming we are witnessing today.

It must be expected that the need for energy will increase even more, as new and large population groups demand their share of the welfare.

The problem...The problem...

http://upload.wikimedia.org/wikipedia/commons/7/76/World_population_increase_history.svg

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The geographic distribution of the world population shows that the densiest areas are those where the inhabitants now demand their share of the welfare, and therefore will need huge resources in form of food and energy. It is expected that this will lead to large milieu problems in those areas, and an increased pressure also on natural marine resources.

Population densities vary between countries. Some nations have large populations and therefore strong national interests relative to natural resources and energy. India and China are typical examples of this.

http://upload.wikimedia.org/wikipedia/commons/b/b1/World_population.PNG

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Population densities in year 2000

"Hotspots" in population densities are found in both developed and undeveloped countries.

http://upload.wikimedia.org/wikipedia/commons/b/bc/Population_density.png

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Definition:Definition: Disturbances were defined by Picket & White (1985) as "any time-limited event which tears up existing ecosystems, societies or population structures and changes resources, substrate availability or the physical environment".

Natural: Distubances act on different scales and with different frequencies. Natural disturbances, such as ocean-level change, ocean temperatures and ocean currents, usually take place over extended time periods. Other natural phenomena have a shorter time scale (hurricanes and cyclones, pests).

Antropogenic: Oil spill, destruction of coral reefs by trawling, eutrophication, and poisonous vaste. Common to both is that they can affect a wide specter of marine habitats, and that they are processes which contribute to the diversity in all ecosystems.

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The increased exploitation of natural resources needed to serve a growing world population has both direct and indirect disturbing effects on marine ecosystems.

Even activities far from the oceanfar from the ocean, like hydropower plants, mountain mining (river-transported pollution), nuclear power plants (leakage of radionucleotides), and chemical industry (river-transported vaste) eventually ends up affecting marine habitats and ecosystems.

A more subtle and slow-working impact, but not less serious, is the increasing deforestation deforestation several places on earth. It leads to soil-erosion and increased river-transport of soil, humus and mud which may cover benthic habitats, and reduced light conditions in areas with coral reefs. Reduced light can also lead to changes in the composition and hierarchy of marine food webs (example: the coronate jellyfish Periphylla periphylla).

These anthropogenic disturbances of biological systems come on top of the natural fluctuations. The new danger now is that mankind with its activities also affects the climate, and thereby the natural fluctuationsclimate, and thereby the natural fluctuations.

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Scale:Scale: There is a tight coupling between the time- and space scales in which disturbances occur. On the smallest scale we have the instantaneous chemical reactions between sediment particles, viral-, and bacterial processes. Futher on via minute-scale predation and metre-scale bioturbidity to tidal cyclusestidal cycluses. The seabed is a mosaic of small societies on different stages of change and recolonization, and together these societies characterize the habitat.

The physical disturbance which results from a single waving crab (Uca sp.) is negligible, but the joint activity of a whole population can turn the sediment surface upside down during one single tidal cyclus.

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http://en.wikipedia.org/wiki/Image:Fiddler_crab.jpg

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Restitution rates:Restitution rates: For small-scale disturbances the restitution times are short; from seconds to weeks, but they increases strongly with the geographic and temporal scale. It may take years and decades to heal the damage to a coral reef which has been destroyed by bottom trawling. When the fish fauna in coastal waters in South Norwayfauna in coastal waters in South Norway was almost wiped our some decades ago, it took surprisingly short time (one or two years) before it was intact again. Therefore, aspects of the mobility of the involved organisms is also part of the picture with respect to recolonosation.

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Different models have been suggested to describe how animal societies react on a disturbance, in form of changes in the societiy's species diversity. Her are two of them:

The IDH hypothesis (Intermediate Disturbance Hypothesis)

Pearson & Rosenberg model

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How to measure effects of human activities

One-variable indexes:

Variation in the occurrence of one particular species has often been used to describe the effects of disturbances. However; this approach does not target changes in the very structure of the society which results from the variation in one or a few species. In most cases the effects of human activity are not species-specific, but may have very different effects on the various components of the society. Wrong scale in the approach can easily lead to wrong conclusions.

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Distribution indexes:

Measures which comprises a set of species counts in a single sample in one graph or histogram. There are a rich flora of such indexes, whereof some may be more sensitive and thereby better fit than others, depending on the circumstances.

The graph to the right shows a situation where a plot of "Taxonomic distinctness" () proved more effective than the common Shannon-Wiener diversity index (H). [Cf the textbook page 469]

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Multivariate techniques:

These techniques combine two or more samples with respect to which degree they contain the same species or different species with variable frequency. They can include both the species themselves, or their respective occurrence or biomass).

The graph to the right shows a MDS (multidimensional scaling) plot of fish and benthic societies in the Irish Sea by use of bottom trawl. Closeness on the plot means similarity of species composition and numeric value.

(MDS plot. Cf textbook p. 470 for figure (MDS plot. Cf textbook p. 470 for figure caption). (Multi-Dimensional Scaling)caption). (Multi-Dimensional Scaling)

MDS plott

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How to detect changes :

If we shall have any possibility to detect effects of human avtivity it is, in light of the enormously complex interactions in marine ecosystems, critically important to ask the right question. Long-term ecological changes are strongly influenced by a fluctuating environment, and it can be very difficult to sort out the importance of single factors among a multitude of milieu effects. Sometimes it is necessary to do laboratory experiments as a support to time series of climatic or ecological data. Monitoring time series must be designed so that they have the necessary statistical power for detecting trends in a time series.

• Type I error: To conclude with difference when there in fact is no difference.• Type 2 error: To conclude with no difference when there in fact is a difference.

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• A priori hypothesis testing

• A posteriori hypothesis testing

• Significance level in multiple tests of the same hypothesis

• The importance of pilot studies and resampling

• Joint significance level from multiple tests (Fisher's omni- bus test)

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Special topicsSpecial topics

http://en.wikipedia.org/wiki/Image:Normal_distribution_pdf.png

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Experimental design

Experiments must be planned so that the data obtained are suitable for the relevant statistical procedures and tests. Examples of basic pre-requisites are:

1. If Anova is planned, at least replicate measurements are needed, so that a mean and variance can be calculated.

2. If frequencies of categorial variables are used, sample size is crucial for detecting significant differences.

3. If trend analysis (increase/decrease) is used, at least 6 plots are necessary for detecting significance at the 5% niveau.

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The cause of changes in marine ecosystems

River transport of terrestrial discharge Estuaries are strongly influenced by the freshwater runoff, and the materials

which the rivers carries with them to the sea. Worldwide, ca 70%70% of the sediments are contributed by rivers. Powerplants, agricultural discharge, flood debris, size of the precipitation area and estuary decide how strong the sedimentation is. The big rivers in the world; the Amazonas and the NileAmazonas and the Nile create enormous deltas which in historic time have been important settling areas for mankind and birth places of civilications.

EutrophicationRivers supply nutrients to the estuaries,and initiate phytoplankton blooms whichmay spread over vast distances with ocean currents and thus result in substan-tial downstream ecosystem disturbances.

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Egypt

The building of the Aswan damAswan dam resulted in a temporary decline of Mediterranean fisheries. It is assumed that the reduced transport of phosphorous during dam construction eventuallly was more than compensated by increased supply from water plants downstream after the building of the dam.

Powerplant constructions

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In the northern Gulf of Mexico, on the Louisiana continental shelf just by the outlet of MississippiMississippi, there are large areas with anoxic conditions in the bottom water in March-December. The severity of the conditions may vary from year to year.

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Natural conditions / eutrophication

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Oil- and gas exploitation on the ocean floor

Release of hydrocarbons and boreslam from drilling platforms affects the surrounding seafloor considerably. The effect is seen as a gradient out from the platform, some places out to 100 meters, but in the North Sea in the North Sea up to 6 km.up to 6 km. Such releases have been substantially reduced with modern technology, so that today the effects from release from shipping is release from shipping is actually much larger that the one from oil production. actually much larger that the one from oil production.

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OIL SPILL

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OIL SPILL


Kaiser part three; ImpactsChapter 14: Disturbances etc DISTURBANCES

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OIL SPILL

Oil in water affects plankton, nekton, (incl. fish), aquaculture, birds and marine mammals.

Oil on the beaches affects coastlines, marinas, freshwater production and seabirds and other animals that live by the sea.



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OIL SPILL

Exxon Valdez

The oil tankship Exxon Valdez was grounded on Bligh Reff at the Kodiak Island, Alaskan Gulf 24. March 1989. It released large amounts of raw oil into the marine nvironment.



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The Exxon Valdez oil spill killed, with certainty, more than 1000 sea otters along the west coast of USA. Some estimates suggest that the number was actually three times larger. This catastrophy, and many others, has had serious consequences for endangered sea otter stock wherever they are found.

OIL SPILL



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The tanker Amoco Cadiz grounded and spilt large amounts of oil on the beaches of Bretagne, France, in March 1978.

Amoco Cadiz



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Amoco Cadiz

Gannet killed by oil spill

Oil destroys the isolating effect of the bird’s plumage and the birds flying ability. The bird will freeze to death, be caught by predators (incl. domestic pets), or succumb by poisoning.



Seagull, killed by oil spill

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OIL SPILLPHYSICS

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OLJESPILL

Plankton is the fundament of all marine food webs. Plankton is very sensitive for the toxic oil products, and many planktonic organisms die at high oil many planktonic organisms die at high oil consentrationsconsentrations. Many other organisms in the food web suffer when the plankton biomass decreases.Fish has sensitive organs for detecting oil and are often able to leaveFish has sensitive organs for detecting oil and are often able to leave contaminated areas if not caught in some way. Juvenile fish are more vulnerable than adults, and a decimation at this life stage will have long-term effects on the stock.Predators in the marine milieu, like scavengers, birds and man, eat in turn the contaminated fish and accumulate toxic compoundsaccumulate toxic compounds in the long run. Oil compounds do not taste good, and both wild fish and farmed fish may not hit the market and thus lead to economic losses. Farmed fish are usually not able to leave the contaminated areas and can be deemed not ediblenot edible.

In open waters, marine mammals such as whales often have the possibility to marine mammals such as whales often have the possibility to leaveleave contaminated areas and thus reduce the danger to their health themselves. However, those that live closer to the shore (dolphins and seals) risk contact with oil compounds on the shores, and get fur damage and food toxification as a resulst.



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MINERAL MINING ON THE OCEAN FLOOR

Exploitation of mineral aggregates (nodules) from the deep ocean floors resultsin intense local disturbance which can last for decades.

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Contaminants

The most important contaminants are radionucleotidesradionucleotides and organic compoundsorganic compounds from energy plants and the industry. PCBPCB (polychlorated biphenyls) are shown to reduce hatchability in bird eggs, while toxic mercurymercury accumulates in bird’s feathers.

Heavy metalsHeavy metals generally accumulate and have toxic effects high up in the food chain (top predators like fish, birds, polar bear), while fat-soluble dioxinsdioxins have toxic effects e.g. through mother’s milk in mammals.

Different flame-inhibitorsflame-inhibitors are shown to give hormonal disturbances in fishes, and may lead to disturbances in sexual expression (”gender bendersgender benders”).”).

Radioactive compounds fra nuclear plants have leaked to the sea and led by ocean currents long distances in the East Atlantic. Leakages from the English nuclear plant SellafieldSellafield have been traced in plant- and animal tissues even in the inner parts of even in the inner parts of Norwegian fjords.Norwegian fjords.

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Climate change

The UN climate panel has concluded that the ongoing worldwide temperature increase is an effect of human activity in form of release of climate gases (carbon dioxide, methane a.a.)climate gases (carbon dioxide, methane a.a.) and water vapourwater vapour.

In the North Sea and along the Norwegian coast there is an ongoing rise in temperature which is unusually strong. Temperature rises have also been recorded earlier (e.g. in the 1930ies), and it is at present not clear if we have entered an irreverible process. The high coastal temperatures are also reflected in increased bottom water temperatures in the Trondheims-fjord during the last 30 years. (next slide).

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From the TBS hydrographical time series in the Trondheimsfjord

The temperatures have oscillated (~ 8-10 year ampl.), with an upgoing trend In the last 10-12 years. In 2007 an ”all times high” was recorded at 500 m depth. The situation in the fjord reflects that on the coast.

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Ocean currents in the East Atlantic connects the various regions and make no area isolated from the others. Thus, all types of pollution can reach even the northernmost regions. For example, dioxinsdioxins have reached alarming consentrations in polar mammals and birds.

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Interaction between factors

In the foregoing, different factors that influence the marine ecosystems have been treated separately for the sake of simplicity. In reality they often work in concertwork in concert, and the effect can be additive or synergetic.

It is notoriously difficult to predict the end outcome of the change in one factor in an ecosystem, because the interplay is so intense and complex between organisms, and between organisms and their environment. The outcomes may be very different, dependent on the particular situation in time and space.

One knows about the occurrence of cascade reactionscascade reactions, where originally small disturbances can ”run away” and lead to substantial overthrowings in the ecosystems.

Times with extensive changes are Bonanza for opportunistic speciesBonanza for opportunistic species. Many of these are evolutionary very old forms with simple life functions. Having survived through hundreds of millions of years of evolution, one can say that they have proved the success of their design.

IMPACTS FROM DISTURBANCES, POLLUTION, AND CLIMATE CHANGE

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