Impacts of climate change on plankton
Martin Edwards, Eileen Bresnan, Kathyrn Cook, Mike Heath, Pierre Helaouet, Christopher Lynam, Robin Raine and Claire Widdicombe
Edwards, M., Bresnan, E., Cook, K., Heath, M., Helaouet, P., Lynam, C., Raine, R. and Widdicombe, C. (2013) Impacts of climate change on plankton, MCCIP Science Review 2013,98-112, doi:10.14465/2013.arc12.098-112
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Major changes have taken place in both the plant (phyto-) and animal (zoo-) plankton of the seas around the British Isles over the last few decades. They include:
- There have been extensive changes in the planktonic ecosystem in terms of plankton production, biodiversity and species distribution which has had effects other marine life.
- In the North Sea the population of the previously dominant and important zooplankton species, (the cold water species Calanus finmarchicus) has declined in biomass by 70% since the 1960s. Species with warmer-water affinities (e.g. Calanus helgolandicus) are moving northward to replace the species but are not numerically abundant or as nutritionally (i.e. less lipid rich) important.
- There has been a northward shift in the distribution of many plankton and fish species by more than 10o latitude over the past 50 years. This shift is particularly associated with the shelf edge current running north along the European continental margin.
- The seasonal timing of some plankton production also altered in response to recent climate changes. This has consequences for plankton predator species, including fish, whose life cycles are timed in order to make use of seasonal production of particular prey species.
- The decline of the European cod stocks in the North Sea due to overfishing may have been exacerbated by climate warming and climate-induced changes in plankton production. It is hypothesised that the survival of young cod in the North Sea depends on the abundance, seasonal timing and size composition of their planktonic prey. As the stocks declined they have become more sensitive to the effects of regional climate warming due to shrinkage of the age distribution and geographic extent.
- Future warming is likely to alter the geographical distribution of primary and secondary pelagic production, affecting ecosystem services such as oxygen production, carbon sequestration and biogeochemical cycling.