Climate change and aquatic ecosystems: DRIVERS, EFFECTS, ADAPTATION

Climate change and aquatic ecosystems: DRIVERS, EFFECTS, ADAPTATION Introduction Jos T.A. Verhoeven Predictions of atmospheric CO2 and global surface...
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Climate change and aquatic ecosystems: DRIVERS, EFFECTS, ADAPTATION Introduction Jos T.A. Verhoeven

Predictions of atmospheric CO2 and global surface temperature: different models + different scenarios IPCC Assessment Report 4 (2007)

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Mean temperature increase

Mean increase oC

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Predicted changes in precipitation

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Sea level rise

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Ocean acidification

Bates, B.C., Z.W. Kundzewicz, S. Wu and J.P. Palutikof, 2008

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Freshwater-related impacts

Streamflow decreases such that present water demand could not be satisfied after 2020; loss of salmon habitat

Groundwater recharge decreases by more than 70% by the 2050’s

Electricity production potential at existing hydropower stations decreases by more than 25% by the 2070’s

Increase of pathogen load due to more heavy precipitation events in areas without good water supply and sanitation infrastructure

Much lower and more variable wheat yield due to increased temperature and precipitation variability Flooded area for annual peak discharge in Bangla Desh increases by at least 25% with a global temperature increase of 2oC

Thickness of small island freshwater lenses declines from 25 to 10 m due to 0.1 m sea-level rise by 2040-2060

runoff

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Impacts on ecosystems • Millennium Ecosystem Assessment (2005): “Freshwater ecosystem biodiversity is the most threatened by climate change impacts” • Effects on ecosystems are often non-linear because of complex interactions • Shifts in stable states are hard to predict • Species mobility with shifting climate zones may be limited

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Climate impacts: Lakes and Streams • Increased stratification, extended growing season, loss of nutrients from surface water in deep lakes • Warming leads to higher anoxia and algal blooms in shallower lakes → species extinctions • Flooding and drought events more frequent (drying up of lakes and streams) • Increased risk of invasive alien species

Climate impacts: Freshwater wetlands • Effects most drastic in inland, continental wetlands • Droughts and excessive rains increase variability • Proportion of water sources will change: precipitation, groundwater, surface water → changes in water chemistry • Wetlands are biodiversity hotspots and might lose amphibians, reptiles • Bogs, depressional wetlands, vernal pools and monsoonal wetlands are the most threatened

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Climate change and aquatic ecosystems: DRIVERS, EFFECTS, ADAPTATION • Idea for symposium came up during last EUROLIMPACS meeting • EUROLIMPACS: European Project to Evaluate Impacts of Global Change on Freshwater Ecosystems (2004-2009) • Lakes, streams, wetlands • REFRESH: follow-up starts next week

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Climate change and aquatic ecosystems: DRIVERS, EFFECTS, ADAPTATION • Erik Jeppesen: Lake ecosystems, with special reference to fish communities • Marten Scheffer: Shallow lake systems, trophic interactions and stable states • Brian Moss: Streams, ponds and lakes, eutrophication and warming • Marcel Klaassen: Migration routes of waterfowl and consequences for aquatic ecosystems

Climate change and aquatic ecosystems: DRIVERS, EFFECTS, ADAPTATION • Rick Battarbee: Climate reconstructions from the past by lake sediments • Luc de Meester: Adaptation of zooplankton in ponds and lakes • Piet Verdonschot: Stream hydrology and impacts on stream biota • Merel Soons: Stream hydrology and recolonization by plants • Daniel Hering: Quality of lake and stream ecosystems in relation to the EU-WFD

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PDSI: Palmer Drought Severity Index

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Observed changes

Changes in run-off

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Current water-stressed areas and examples of major problems

Damage to riparian ecosystems due to flood protection along Elbe river

Multi-year droughts in USA and southern Canada

Huanghe River has temporarily run dry due to precipitation decrease and irrigation

Land subsidence and land slides in Mexico city Rural water supply affected by extended dry season in Benin

Water supply affected by shrinking glaciers in Andes

Area of Lake Chad declining Water supply reduced by erosion and sedimentation in reservoirs in north-east Brazil

Health problems due to arsenic and fluoride in groundwater in India Flood disasters in Bangla Desh (more than 70% of the country inundated in 1998)

Water stress indicator: withdrawal to availability ratio

Damage to aquatic ecosystems due to decreased streamflow and increased salinity in Murray-Darling basin

No stress low stress mid stress high stress very high stress

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Projected impacts

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Impacts on water services

Center for Wetland Ecology Wednesday 14 April, Utrecht University, Symposium: Biogeochemical processes in wetlands: new insights in complex matters Mike Jetten - Annamox bacteria in wetlands Eric Struyf - Silica biogeochemistry in wetlands Mariet Hefting - Decomposition, warming and nitrogen enrichment Peter Spierenburg – CO2 and plants in softwater lakes Thomas Stal - Diatom biofilms and sediment stabilization Annemiek Kooijman - Mineralization of organic, wet soils

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