Vulnerability of open ocean food webs in the tropical Pacific to climate change Presented by Valerie Allain
Authors 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
Photo: Marc Taquet, FADIO, IRD/IFREMER Photo: Photoshot/Superstock
The tuna food web Food webs are complex
The tuna food web Light Nutrients Phytoplankton at the base of the food web require light and nutrients to develop
Photo: Gustaaf Hallegraeff Phytoplankton
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 present future GYRES Exchanges between deep rich water and surface poorer waters ↘ of nutrients reaching the surface where photosynthesis can occur
Impact of climate change present future Equatorial upwelling Exchanges between deep rich water and surface poorer waters ↘ nutrients reaching the surface where photosynthesis can occur
Impact of climate change Effect on phytoplankton and zooplankton Today 2050 2035 present
Impact of climate change Effect on phytoplankton and zooplankton 2035 2035 2050 present ↘ of phytoplankton and zooplankton
Impact of climate change Effect on phytoplankton and zooplankton 2050 2035 2050 present ↘ of phytoplankton and zooplankton
Impact of climate change Effect on phytoplankton and zooplankton 2100 2035 2050 present ↘ of phytoplankton and zooplankton
Impact of climate change Effect on micronekton Image: Valerie Allain, SPC ↘ micronekton
Uncertainties and adaptation Need to establish long-term observations for biological processes Phytoplankton Image: Valerie Allain, SPC
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 Micronekton Image: Rudy Kloser, CSIRO Image: Valerie Allain, SPC Image: Valerie Allain, SPC
Uncertainties and adaptation Need to establish long-term observations for biological processes Predators Photo: 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