Marine Climate Change Impacts
Phytoplankton image by M.Edwards

Climate Impacts and Marine Plankton

Plankton constitutes the main primary and secondary biomass in marine ecosystems and, as a result of being at the base of the trophic pyramid, plays a fundamental role in marine food-webs. Therefore, any change in the plankton will have consequences on the marine food-web and on other trophic levels (e.g. fish, seabirds) through bottom-up control. In the North Atlantic both phytoplankton and zooplankton species and communities have been associated with Northern Hemisphere Temperature (NHT) trends and variations in the North Atlantic Oscillation (NAO) index. These have included changes in species distributions and abundance, the occurrence of sub-tropical species in temperate waters, changes in overall phytoplankton biomass and season length, changes in the North Sea ecosystem, community shifts, phenological changes and changes in species interactions.

Recent macroscale research has shown that the increase in regional sea temperatures has triggered a major re-organisation in calanoid copepod species composition and biodiversity over the whole North Atlantic basin. During the last 40 years there has been a northerly movement of warmer water plankton by 10° latitude in the north-east Atlantic and a similar retreat of colder water plankton to the north. This geographical movement is much more pronounced than any documented terrestrial study, presumably due to advective processes (see biogeographic case-study below). Over the last decade there has been a progressive increase in the presence of warm-water/sub-tropical species into the more temperate areas of the north-east Atlantic.

In terms of marine phenological changes and climate, the plankton of the North Sea has been extensively studied using Continuous Plankton Recorder data. Using 66 taxa it was found that the plankton community was responding to changes in SST by adjusting their seasonality (in some cases a shift in seasonal cycles of over six weeks was detected), but more importantly the response to climate warming varied between different functional groups and trophic levels, leading to mismatch. It is thought that temperate marine environments are particularly vulnerable to phenological changes caused by climatic warming because the recruitment success of higher trophic levels is highly dependent on synchronisation with pulsed planktonic production. The rapid changes in plankton communities observed over the last few decades in the North Atlantic, related to regional climate changes, have enormous consequences for other trophic levels and biogeochemical processes. See phenology case-study below.

Scientific case-studies and current ecological status
Reorganisation of North Atlantic Marine Copepod Biodiversity and Climate: Beaugrand et al., 2002, SCIENCE
Biogeographical changes
Climate impacts on plankton biogeography (pdf)
Copepod image by Paul Hampton. Publication copyright Nature publishing group
Phenological changes
Climate impacts on plankton phenology (pdf)
Ecological Status Report cover image
Current ecological status
Current North Atlantic ecological status report (pdf)
Key references
Beaugrand, G. & Reid, P.C. 2003. Long-term changes in phytoplankton, zooplankton and salmon related to climate.
      Global Change Biology, 9, 801-817.

Beaugrand, G., Reid, P.C., Ibanez, F., Lindley, J.A. & Edwards, M. 2002. Reorganisation of North Atlantic marine
      copepod biodiversity and climate. Science, 296, 1692-1694.

Beaugrand, G., Brander, K.M., Lindley, J.A., Souissi, S. & Reid, P.C. 2003. Plankton effect on cod recruitment in
      the North Sea. Nature, 426, 661-664.

Edwards, M. & Richardson, A.J. 2004. Impact of climate change on marine pelagic phenology and trophic
      mismatch. Nature, 430, 881-884.

Edwards, M., John,A.W.G., Johns, D.G., & Reid, P.C. 2001. Case-history and persistence of the non-indigenous       diatom Coscinodiscus wailesii in the north-east Atlantic. Journal of the Marine Biological Association
       of the United Kingdom 81(2): 207-211

Edwards, M., Beaugrand, G., Reid, P.C., Rowden, A.A. &Jones, M.B. 2002. Ocean climate anomalies and
      the ecology of the North Sea. Marine Ecology Progress Series 239: 1-10.

Edwards, M., Licandro, P., John, A.W.G. & Johns, D.G. 2005. Ecological Status Report: results from the CPR       survey 2003/2004. SAHFOS Technical Report, No. 2: 1-6. ISSN 1744-075.

Fromentin, J.-M. & Planque, B. 1996. Calanus and environment in the eastern North Atlantic. II. Influence of the       North Atlantic Oscillation on C. finmarchicus and C. helgolandicus. Marine Ecology Progress Series
      134(1-3): 111-118.

Richardson, A.J. & Schoeman, D.S. 2004. Climate impact on plankton ecosystems in the Northeast Atlantic.
      Science, 305, 1609-1612.

Reid, P.C., Edwards, M., Hunt, H.G. & Warner, A.J. 1998. Phytoplankton change in the North Atlantic.
      Nature, 391, 546.

Reid, P. C. & Edwards, M. 2001. Plankton and climate. Encyclopaedia of ocean sciences.
      J. H. Steele, Harcourt Press: 2194-2200.
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