SAHFOS predicts the disappearance of one of the main North Sea zooplankton
There is growing evidence that climate change can modify the distribution of marine organisms, including the microscopic plant-like cells and animals that constitute plankton. Copepods, tiny planktonic crustaceans of a few millimetres, are the main food source for many marine predators, from jellyfish to marine mammals. The Continuous Plankton Recorder (CPR) Survey run by the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) is the longest and geographically extensive marine biological survey in the world. Using new modelling techniques, researchers at SAHFOS have found that one of the main copepod species in the North Atlantic Ocean, Calanus finmarchicus, is at risk of disappearance in the North Sea due to increasing water temperatures. This species feeds on phytoplankton (microscopic plant-like organisms) and in turn is eaten by larger organisms, including Atlantic cod, mackerel and herring , some of the most exploited fish in the Atlantic, because it is a particularly rich source of oils essential for survival of larger fish and whale species. However, C. finmarchicus , is being progressively replaced in the North Sea by other smaller and less nutritious copepods species. This species change has already been related to the collapse of some fish stocks and the recruitment failure in North Sea birds.
Read more: Helaouët P, Beaugrand G, Reid P.C. (2010) Macrophysiology of Calanus finmarchicus in the North Atlantic Ocean. Progress in Oceanography. doi:10.1016/j.pocean.2010.11.003
Contact at SAHFOS : Pierre Helaouët
(left) Distribution maps of the copepod Calanus finmarchicus in the North Atlantic during the 1960s (A) and in recent years (B), showing how this species is progressively disappearing in the North Sea. (right) C. finmarchicus juvenile (pre-maturity stage).
