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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. Authors.

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Vulnerability of open ocean food webs in the tropical Pacific to climate change

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  1. Vulnerability of open ocean food webs in the tropical Pacific to climate change Presented by Valerie Allain

  2. 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

  3. Photo: Photoshot/Superstock Photo: Marc Taquet, FADIO, IRD/IFREMER

  4. The tuna food web Food webs are complex

  5. The tuna food web Light Nutrients Phytoplankton at the base of the food web require light and nutrients to develop

  6. Photo: Gustaaf Hallegraeff Phytoplankton

  7. The five oceanic provinces

  8. The five oceanic provinces • Warm Pool Normal El Niño

  9. The five oceanic provinces • North and South Gyres (Case 3) and equatorial divergence (Case 4)

  10. Impact of climate change • Surface area of the provinces Present day

  11. The impact of climate change • Surface area of the provinces 2035 ↘ rich equatorial divergence ↗ poorer gyres and warm pool

  12. Impact of climate change • Surface area of the provinces 2050 ↘ rich equatorial divergence ↗ poorer gyres and warm pool

  13. Impact of climate change • Surface area of the provinces 2100 ↘ rich equatorial divergence ↗ poorer gyres and warm pool

  14. 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

  15. 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

  16. Impact of climate change 2050 Today present 2035 • Effect on phytoplankton and zooplankton present

  17. Impact of climate change 2050 2035 present 2035 • Effect on phytoplankton and zooplankton present ↘ of phytoplankton and zooplankton

  18. Impact of climate change 2050 2050 present 2035 • Effect on phytoplankton and zooplankton present ↘ of phytoplankton and zooplankton

  19. Impact of climate change 2050 2100 present 2035 • Effect on phytoplankton and zooplankton present ↘ of phytoplankton and zooplankton

  20. Impact of climate change • Effect on micronekton Image: Valerie Allain, SPC ↘ micronekton

  21. Uncertainties and adaptation • Need to establish long-term observations for biological processes Phytoplankton Image: Valerie Allain, SPC

  22. Uncertainties and adaptation • Need to establish long-term observations for biological processes Zooplankton

  23. Uncertainties and adaptation • Need to establish long-term observations for biological processes Image: Valerie Allain, SPC Micronekton Image: Valerie Allain, SPC Image: Rudy Kloser, CSIRO

  24. Uncertainties and adaptation • Need to establish long-term observations for biological processes Predators Photo: Peter Sharples

  25. 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

  26. 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

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