Impact of large-scale climatic changes on pelagic ecosystems in the North Atlantic Grégory Beaugrand CNRS, UMR 8013 ELICO Station Marine Wimereux Université des sciences et technologies de Lille 1 BP 80, Wimereux France Reykjavik, 12-14th March 2005

Objectives of this talk To document responses of plankton to hydro-climatic forcing To show the potential consequences of climate-induced plankton changes for the structure and the functioning of the pelagic ecosystems, for higher trophic levels (Fish) and biogeochemical cycles

Continuous Plankton Recorder (CPR) Survey Sir Alister Hardy Herring Packers & Drifters First tow September 1931

The CPR sampler

CPR sampling:

Information in the CPR database >400 species or taxa DinoflagellatesDiatomsCopepods 108 taxa Other zooplankton Meroplankton Euphausiids

Large-scale climatic forcing

Climatic variability in the North Atlantic Ocean NAO (January to March) 1988 NAO EA (September to April) 1982 EA EA - Jet (April to August) 1987 EA-jet

Northern Hemisphere Temperature anomalies (moving average)

Long-term changes in sea surface temperature ( ) From Beaugrand et al. (2002). Science. 296:

What kind of biological consequences are expected under climatic warming? Changes in the range and spatial distribution of species Shifts in the location of biogeographical boundaries, provinces and biomes Change in the phenology of species (e.g. earlier reproductive season) Modification in dominance (e.g. a key species can be replaced by another one) Change in diversity Change in other key functional attributes for marine ecosystems Change in structure and dynamics of ecosystem with possible regime shifts Major impact for marine exploited resources and biogeo- chemical processes (e.g. sequestration of CO 2 by the ocean)

Plankton response to hydro-climatic forcing 1. Biogeographical shifts

Warm-temperate shelf- edge species Mean number of species per association Temperate shelf- edge species Beaugrand et al. (2002) Science. Vol

Cold-temperate (mixed water) species Subarctic species Mean number of species per association Beaugrand et al. (2002) Science. Vol

Plankton response to hydro-climatic forcing 2. Changes in biodiversity

Long-term monthly changes in calanoid copepod diversity The North Sea (north and central part) Mean number of calanoid species per CPR sample Years MONTHSMONTHS Line in black: warm-temperate species Line in red: temperate species Before 1980After 1980

Statistical modelling the seasonal changes in diversity

r² = 0.93 n = 540 p ACF < Taxonomic diversity Size diversity Relationships between taxonomic diversity and size diversity for calanoid copepods Beaugrand et al. (in prep)

Plankton response to hydro-climatic forcing 3. Relationships between changes in plankton and fish

Beaugrand (2004) PROOCE Gadoid species (cod) SST NHT anomalies plankton change Flatfish salinity Westerly wind plankton change

Regime shifts in the North Sea and in the Pacific Ocean Beaugrand & Ibanez (in press, MEPS) Beaugrand G (2004) Progress in Oceanography

Regime shifts in the North Sea and in the Pacific Ocean Beaugrand & Ibanez (in press, MEPS) Beaugrand G (2004) Progress in Oceanography

Plankton response to hydro-climatic forcing 4. Relationships between changes in plankton and the Atlantic salmon

NHT anomalies Phytoplankton C. finmarchicus Salmo salar 1987 Beaugrand and Reid (2003) Global Change Biology

Local hydro-climatic changes in the north-east Atlantic and the North Sea: SMW / MRPP analyses

Beaugrand & Reid, 2003 Global Change Biology 9, Cluster Analysis: grouping years as a function of physical and biological characters Variables : Sea SurfaceTemperature NE Atlantic Northern Hemisphere Temperature North Atlantic Oscillation Phytoplankton Zooplankton (3 taxa) Salmon catches

Plankton response to hydro-climatic forcing 5. Relationships between changes in plankton and cod

Plankton indicator of larval cod survival MarchOctober Calanus (from egg to adults) July Pseudocalanus Euphausiids fish larvae Total biomass of calanoid copepods Mean size of calanoid copepod (ratio prey length/larval length=0.05)

Beaugrand et al. (2003) Nature. Vol Long-term change in the plankton index and cod recruitment (at age 1, one-year lag)

Plankton and cod recruitment Beaugrand et al. (2003) Nature. Vol

Plankton and cod recruitment

Consequences of plankton changes on higher trophic level (3) Mean size of calanoid copepod prey Ratio length of prey / length of larvae 1. Mismatch between size of prey and larval cod Beaugrand, et al. (2003) Nature. Vol

Long-term changes in the abundance of two key species in the North Sea Percentage of C. helgolandicus Reid et al. (2003)

Consequences of plankton changes on higher trophic level (3) 2. Mismatch between the timing of calanus prey and larval cod Abundance of C. finmarchicusAbundance of C. helgolandicus Beaugrand, et al. (2003) Nature. Vol

Consequences of plankton changes on higher trophic level (3) 3. Quantitative changes unfavourable for larval/juvenile survival Mean biomass of calanoid copepod preys Abundance of euphausiids Beaugrand, et al. (2003) Nature. Vol

warming of temperature Decrease in the number of prey (-) Energetic gain Growth and survival Reduction in recruitment Larval metabolism Energetic demand (+) (-) (+) Energetic imbalance (-) Overfishing

Plankton response to hydro-climatic forcing 6. Changes in the functioning of pelagic ecosystems with possible consequences for biogeochemical cycles Exemple of the North Sea

Functional warming of North Sea marine ecosystems: decrease in the mean size of calanoid copepods Eigenvector 2 (17.52%) Principal component 2 (in black) Beaugrand et al. (in prep)

Long-term monthly changes in the minimum turnover of biogenic carbon Years ( ) Months Minimum turnover (in day) Increase in the ecosystem metabolism

Long-term monthly changes in the mean residence time of carbon above 50 m Years ( ) Months Residence time (in day) Potential decrease in carbon sink in the North Sea

Response of the pelagic ecosystem to climate change Cold period: Warm period: Increase in carbon recycling (ecosystem metabolism) Decrease in exportation

Adaptation of North Sea ecosystems to a new regime Minimum size ( ) Diversity ( ) Biomass ( ) Difference between the period and

Shift in the location of the main biogeographical boundaries Analysis with mean size, diversity, total biomass and temperature First principal component

Response of the pelagic ecosystem to climate change Diatom diversityDinoflagellate diversity Mean number of species per CPR sample

Conclusions Examination of data from the CPR survey have revealed major changes in the plankton ecosystems in European seas Plankton ecosystem changes are related to large-scale climatic variability (e.g. NAO and NHT) Strong potential consequences for exploited resources

Aknowledgments Philip C Reid (SAHFOS) Keith Brander (ICES, Copenhagen) Frederic Ibanez (LOV, Villefranche-sur-mer)

Mean size of calanoid copepods (minimum size of female) G. Beaugrand

Biotic anomalies around the United Kingdom Biological materials: Euphausiids, Calanus, phytoplankton colour Calanoid copepod biomass, mean size of calanoid copepods Statistical analysis: Three-mode PCA Results: Major biotic anomalies in the North Sea during the 1990s (start of the change during the 1980s) Beaugrand (in preparation)