Impact of large-scale climatic changes on pelagic ecosystems in the North Atlantic

1
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, 62930 Wimereux France Email
Gregory.Beaugrand_at_univ-lille1.fr
Reykjavik, 12-14th March 2005
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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

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Continuous Plankton Recorder (CPR) Survey
First tow September 1931
Herring Packers
Drifters
Sir Alister Hardy
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The CPR sampler
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CPR sampling 1946-2002
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Information in the CPR databasegt400 species or
taxa
Dinoflagellates
Diatoms
Copepods 108 taxa
Other zooplankton Meroplankton Euphausiids
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Large-scale climatic forcing
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Climatic variability in the North Atlantic Ocean
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Northern Hemisphere Temperature anomalies (moving
average)
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Long-term changes in sea surface temperature
(1960-1997)
From Beaugrand et al. (2002). Science. 296
1692-1694.
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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
CO2 by the ocean)
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Plankton response to hydro-climatic forcing
1. Biogeographical shifts
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Warm-temperate shelf- edge species
Temperate shelf- edge species
Mean number of species per association
Beaugrand et al. (2002) Science. Vol. 296.
1692-1694.
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Cold-temperate (mixed water) species
Subarctic species
Mean number of species per association
Beaugrand et al. (2002) Science. Vol. 296.
1692-1694.
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Plankton response to hydro-climatic forcing
2. Changes in biodiversity
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Long-term monthly changes in calanoid copepod
diversity The North Sea (north and central part)
Before 1980
After 1980
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Statistical modelling the seasonal changes in
diversity
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Relationships between taxonomic diversity and
size diversity for calanoid copepods
6
5
4
Size diversity
3
2
r² 0.93 n 540 pACF lt0.01
1
0
0
1
2
3
4
Taxonomic diversity
Beaugrand et al. (in prep)
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Plankton response to hydro-climatic forcing
3. Relationships between changes in plankton and
fish
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Beaugrand (2004) PROOCE
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Regime shifts in the North Sea and in the Pacific
Ocean
Beaugrand Ibanez (in press, MEPS)
Beaugrand G (2004) Progress in Oceanography
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Regime shifts in the North Sea and in the Pacific
Ocean
Beaugrand Ibanez (in press, MEPS)
Beaugrand G (2004) Progress in Oceanography
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Plankton response to hydro-climatic forcing
4. Relationships between changes in plankton and
the Atlantic salmon
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NHT anomalies
Phytoplankton
C. finmarchicus
Salmo salar
Beaugrand and Reid (2003) Global Change Biology
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Local hydro-climatic changes in the north-east
Atlantic and the North Sea SMW / MRPP analyses
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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
Beaugrand Reid, 2003 Global Change Biology 9,
801-807
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Plankton response to hydro-climatic forcing
5. Relationships between changes in plankton and
cod
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Plankton indicator of larval cod survival
fish larvae
Euphausiids
Calanus (from egg to adults)
Pseudocalanus
March
October
July

• Total biomass of calanoid copepods
• Mean size of calanoid copepod (ratio prey
  length/larval length0.05)

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Long-term change in the plankton index and cod
recruitment (at age 1, one-year lag)
Beaugrand et al. (2003) Nature. Vol. 426.
661-664.
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Plankton and cod recruitment
Beaugrand et al. (2003) Nature. Vol. 426.
661-664.
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Plankton and cod recruitment
Beaugrand et al. (2003) Nature. Vol. 426.
661-664.
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Consequences of plankton changes on higher
trophic level (3)
1. Mismatch between size of prey and larval cod
Beaugrand, et al. (2003) Nature. Vol. 426.
661-664.
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Long-term changes in the abundance of two key
species in the North Sea
Percentage of C. helgolandicus
Reid et al. (2003)
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Consequences of plankton changes on higher
trophic level (3)
2. Mismatch between the timing of calanus prey
and larval cod
Beaugrand, et al. (2003) Nature. Vol. 426.
661-664.
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Consequences of plankton changes on higher
trophic level (3)
3. Quantitative changes unfavourable for
larval/juvenile survival
Beaugrand, et al. (2003) Nature. Vol. 426.
661-664.
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warming of temperature
(-)
()
Decrease in the number of prey (-)
Larval metabolism
()
(-)
()
Energetic demand
Energetic gain
Energetic imbalance
(-)
Growth and survival
(-)
Reduction in recruitment
Overfishing
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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
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Functional warming of North Sea marine
ecosystems decrease in the mean size of calanoid
copepods
Principal component 2 (in black)
Eigenvector 2 (17.52)
Beaugrand et al. (in prep)
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Long-term monthly changes in the minimum turnover
of biogenic carbon
12
11
7.5
10
7
9
8
6.5
7
Months
Minimum turnover (in day)
6
6
5
5.5
4
5
3
2
4.5
1
60
65
70
75
80
85
90
95
Increase in the ecosystem metabolism
Years (1958-1999)
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Long-term monthly changes in the mean residence
time of carbon above 50 m
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3.2
11
3
10
9
2.8
8
2.6
Residence time (in day)
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Months
2.4
6
5
2.2
4
2
3
1.8
2
1
60
65
70
75
80
85
90
95
Potential decrease in carbon sink in the North Sea
Years (1958-1999)
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Response of the pelagic ecosystem to climate
change
Warm period 1987-2002
Cold period 1964-1981

• Increase in carbon recycling (ecosystem
  metabolism)
• Decrease in exportation

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Adaptation of North Sea ecosystems to a new regime
Minimum size (1958-2002)
Diversity (1958-2002)
Biomass (1958-2002)
Difference between the period 1964-1980 and
1987-2002
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Shift in the location of the main biogeographical
boundaries
1965-1981
1987-2002
First principal component
First principal component
Analysis with mean size, diversity, total biomass
and temperature
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Response of the pelagic ecosystem to climate
change
Diatom diversity
Dinoflagellate diversity
Mean number of species per CPR sample
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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

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Aknowledgments

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

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