Vulnerability of open ocean food webs in the tropical Pacific to climate change
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Vulnerability of open ocean food webs in the tropical Pacific to climate change Presented by Valerie Allain
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Vulnerability of open ocean food webs in the tropical Pacific to climate change. Presented by Valerie Allain. Authors. - PowerPoint PPT Presentation
Transcript of Vulnerability of open ocean food webs in the tropical Pacific to climate change
Vulnerability of open ocean food webs in the tropical Pacific to
climate change Presented by
Valerie Allain
This presentation is based on Chapter 4 ‘Vulnerability of open ocean food webs in the tropical Pacific to climate change’ in the book Vulnerability of Tropical Pacific Fisheries and Aquaculture to Climate Change, edited by JD Bell, JE Johnson and AJ Hobday and published by SPC in 2011.
The authors of Chapter 4 are: Robert Le Borgne, Valerie Allain, Shane P Griffiths, Richard J Matear, A David McKinnon, Anthony J Richardson and Jock Young
Authors
Photo: Marc Taquet, FADIO, IRD/IFREMER
Photo: Photoshot/Superstock
The tuna food web
Food webs are complex
The tuna food web
Nutrients
Phytoplankton at the base of the food web require light and nutrients to develop
Light
PhytoplanktonPhoto: Gustaaf Hallegraeff
The five oceanic provinces
The five oceanic provinces• Warm Pool
Normal El Niño
The five oceanic provinces• North and South Gyres (Case 3) and equatorial
divergence (Case 4)
Impact of climate change
• Surface area of the provinces
Present day
The impact of climate change
• Surface area of the provinces
2035
↘ rich equatorial divergence↗ poorer gyres and warm pool
Impact of climate change
• Surface area of the provinces
2050
↘ rich equatorial divergence↗ poorer gyres and warm pool
Impact of climate change
• Surface area of the provinces
2100
↘ rich equatorial divergence↗ poorer gyres and warm pool
Impact of climate change
• GYRESExchanges
between deep rich water and surface poorer waters
↘ of nutrients reaching the surface where photosynthesis can occur
present future
Impact of climate change
↘ nutrients reaching the surface where photosynthesis can occur
present future
• Equatorial upwelling
Exchanges between deep rich water and surface poorer waters
presentpresent
Impact of climate change• Effect on phytoplankton and zooplankton
20352050Today
presentpresent
Impact of climate change• Effect on phytoplankton and zooplankton
↘ of phytoplankton and zooplankton
203520502035
presentpresent
Impact of climate change• Effect on phytoplankton and zooplankton
↘ of phytoplankton and zooplankton
203520502050
presentpresent
Impact of climate change• Effect on phytoplankton and zooplankton
↘ of phytoplankton and zooplankton
203520502100
Impact of climate change• Effect on micronekton
↘ micronektonIm
age:
Val
erie
Alla
in,
SP
C
Uncertainties and adaptation• Need to establish long-term observations for
biological processes
Image: Valerie Allain, SPCPhytoplankton
Uncertainties and adaptation• Need to establish long-term observations for
biological processes
Zooplankton
Uncertainties and adaptation• Need to establish long-term observations for
biological processes
Longitude d.dm
Depth
m
06-13-2008 NZ-Aust start lat-40.4641 end lat -40.6744
150 152 154 156 158 160 162 164 166 168 170
0
200
400
600
800
1000
1200 -80
-75
-70
-65
-60
Micronekton
Image: Rudy Kloser, CSIRO
Imag
e: V
aler
ie A
llain
, S
PC
Image: Valerie Allain, SPC
Uncertainties and adaptation• Need to establish long-term observations for
biological processes
PredatorsPhoto: Peter Sharples
Uncertainties and adaptation
• Global reduction of greenhouse gas emissions
• Appropriate tuna fisheries management measures can help maintain healthy food webs and fisheries giving better chances to food webs and tuna to adapt to climate change
Conclusions
• Food webs are complex, based on phytoplankton• 5 provinces and food webs in the Pacific• Reduction of the production• Long-term monitoring is needed• Reducing greenhouse gas emissions and
managing tuna fisheries
