Royal Netherlands Institute for Sea Research

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Climate Change Impacts onMarine Biodiversity and

Ecosystem Services

Carlo HeipRoyal Netherlands Institute of Sea Research

European Institute for the Study of Marine Biodiversity and EcosystemFunctioning MarBEF+

Green Week, Brussels 2 June 2010

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§ to present the state of the art knowledge on

climate change impacts on marine biodiversity and

ecosystem services and potential consequences on

human societies and economy.

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Sea SurfaceTemperature

Thermal expansion

Storm frequency andintensity

Ocean currents

Stratification

Ocean acidification

Atmospherictemperature

Melting of Ice

Sea Level Rise

CO2

Deep circulation

Ice biota disappear

Distribution changes, mortality

Distribution changes

Distribution changes

Destruction of coastalhabitats

Reduction of calcification

Productivity changes

The chain of eventsEffects on Marine Biodiversity

Low oxygenDistribution changes, mortality

Destruction of coastalhabitats

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Sea SurfaceTemperature

Thermal expansion

Storm frequency andintensity

Ocean currents

Stratification

Ocean acidification

Atmospherictemperature

Melting of Ice

Sea Level Rise

CO2

Deep circulation

The chain of events

Low oxygen

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Effects on Biodiversity and Ecosystem Services

§ Indirect effect of increasing CO2: Sea surface

temperature

• Changing distributions and food webs: example of the

Arctic

• Increasing stratification, lower productivity and hypoxia

§ Direct effect of increasing CO2

• Ocean acidification

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Increasing SST: what is the evidence?

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Effect: changing distributions

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Sp

eci

es

rich

ne

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Fish Species Richness in the North Sea has strongly

increased over time

o Small southern species increase

o Large northern species decrease their range

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Fig. 1. Water temperatures in the Arctic are increasing (Walczowski et al. 2007)

4

3

2

1

-2 0 2 4 6temperature

years

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Climate Change and Overexploitation

lead to decreasing

numbers of top predators.

Example: Bluefin Tuna caught

in the North Sea UK 1933 (upper two)

Denmark (lower) 1946. The species

has now disappeared completely.

(MacKenzie and Myers, 2007)

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Warm and light surface waters

Cold and heavy deep waters

Result = stratificationStable situation

Temperature and Stratification

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Temperature and Stratification

§ Models with rising CO2 indicate that upper ocean

stratification and stability will increase and mixing

will decrease in the next 50 years with rising SST.

§ These conditions increase the dominance of

picoplankton (= very small plankton) relative to

diatoms and other microplankton.

§ It is reasonable to assume that NPP (Net Primary

Production) by picoplankton will increase and NPP

by larger microplankton will decrease, especially at

low and mid-latitudes.

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1999-2004

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Primary production is correlatedwith stratification

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SST, stratification and oxygen

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Eastern Tropical Atlantic

Central Equatorial Atlantic

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Acidification: the other CO2

problem

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Surface pH will decrease with increased CO2

Wallace in SOLAS programme plan 2001

+Calcifying Organisms

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Climate: coccolithophorids, albedo and acidification

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Example: coccolithophorids

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Coccoliths and albedo

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Cloud albedo

§Coccolithophorids produce DMS (dimethylsulfide)

(over 100 times more than diatoms).

§After the cells die, some of this DMS eventually

ends up as cloud condensation nuclei (CCN) in the

atmosphere.

§These CCN help to stimulate cloud formation. In

this way, coccolithophore productivity helps to

increase the reflectiveness (albedo) of the planet

by allowing more clouds to form.

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Acidification effects in corals

Fig. 18: Scleractiniancoral Oculinapatagonica after being maintained for 12 months in (A) normal seawater (pH=8.2) and (B) acidified seawater (pH=7.4). (C) Solitary polyps reforming a colony and calcifying after being transferred back to normal seawater. (D) Percent change in biomass and total buoyant weight over 12 months (pH = 7.4) and control (pH = 8.2) seawater (N = 20). Scale bars indicate 2 mm. From Fine & Tchernov(2007).

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Ecosystem services, humansocieties and the economy

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§Coastal waters account for just 7% of the total

area of the ocean. However the productivity of

ecosystems such as the continental shelves, coral

reefs, seagrass beds and mangroves means that

this small area forms the basis of the world’s

primary fishing grounds, supplying an estimated

50% of the world’s fisheries.

§They provide vital nutrition for close to 3 billion

people, as well as 50% of animal protein and

minerals to 400 million people of the least

developed countries in the world.

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§Each day, more than a hundred million tons of

carbon in the form of CO2 are fixed into organic

material by the microscopic plants of the upper

ocean, and each day a similar amount of organic

carbon is transferred into marine ecosystems by

sinking and grazing.

§The entire phytoplankton biomass of the global

oceans is consumed every two to six days

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§The ocean’s vegetated habitats, in particular

mangroves, salt marshes and seagrasses, cover

<0.5% of the sea bed. These form earth’s blue

carbon sinks and account for more than 50% of all

carbon storage in ocean sediments.

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Conclusions

§ Impacts of climate change on marine biodiversity are

complex and often specific for the oceans

§ Marine biodiversity is changing due to climate change and

increasing overexploitation of higher trophic levels, or both

§ Effects on biodiversity of increasing temperature through

stratification and oxygen content, and of decreasing pH

through impaired calcification, are becoming visible at global

scales

§ This may impair the capacity of the oceans to sequester

carbon, to protect coastal environments against storms and

floods, and to provide food for human populations.

§ Biodiversity can be used for our benefit in mitigating the

effects of climate change

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Thank you for your attention

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