Harmful phytoplankton species increasing in some regions of the North sea over last 40 years
Phytoplankton is made up of millions of microscopic, plant-like cells floating in the oceans which provide food zooplankton (microscopic animal plankton) and help absorb vast amounts of carbon dioxide, a key greenhouse gas, from the atmosphere. Not all phytoplankton are helpful; some dinoflagellate species produce toxic environments by absorbing all dissolved oxygen, thereby suffocating other marine creatures, and producing poisonous compounds that taint and spoil shellfish flesh, which if eaten can poison humans. Researchers at the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) have been monitoring the distribution and abundance of these harmful plankton species in the North-East Atlantic using the Continuous Plankton Recorder (CPR). They found that the occurrence of harmful dinoflagellate species has increased over the last 40 years, and that these species have moved steadily eastwards towards the coast of Scandinavia. It is thought that a climate system called the North Atlantic Oscillation has led to warmer and wetter conditions, which along with an overall increase in air and sea surface temperatures has probably favoured the growth of these harmful species.
Read more: Edwards, M., Johns, D.G., Leterme, S.C., Svendsen, E. and Richardson, A.J., 2006. Regional climate change and harmful algal blooms in the northeast Atlantic. Limnology and Oceanography, 51(2), 820-829.
Contact at SAHFOS : Martin Edwards
(left) Anomaly maps showing where four different harmful phytoplankton species have recently increased (shades of red) or decreased (shades of blue). The anomaly has been calculated as the difference between the long-term mean (1960-89) and post 1990s (1990-2002) distributions. (right, from top to bottom) bloom of the dinoflagellate species Noctiluca (picture from de Vleet, Ecomare), Dinophysis and Prorocentrum sampled by the CPR.
