Global warming will bring conditions that encourage harmful cyanobacterial blooms, which smother aquatic plants and deprive other aquatic organisms of sunlight, Hans Paerl and Jef Huisman explain in April issue of Science (320, 57-58).
Rising temperatures give cyanobacteria a competitive advantage over other phytoplankton and provide them with a longer growth period. Global warming may also lead to more blooms by altering patterns of precipitation and drought, ultimately supplying the bacteria with more nutrients. Some cyanobacteria have already expanded their geographical ranges. The authors recommend more detailed studies of the population dynamics in cyanobacterial blooms, and they say that water managers will have to accommodate the effects of climatic change in their strategies to combat the expansion of cynaobacterial blooms.
The ‘Perspective’ article considers mainly freshwater bodies and enclosed brackish seas like the Baltic, but rising temperatures and increased pCO2 in the open ocean arguably favour Trichodesmium geographic expansion (Hutchins et al., 2007. Limn. & Oc. 52-4).
H.W. Paerl and J. Huisman*, 2008. Blooms Like It Hot, Science 320, 57-58
- Hutchins D., ‘Ocean Acidification or CO2 Fertilization?’, Ocean Carbon and Biogeochemistry Vol 1, No 1, 2008.
While CO2 acidification will be to the detriment of calcifying species like corals and coccolithophores, a high-CO2 world seems to offer all the advantages for blooming cyanobacteria, together will all the ecological impacts on the food chain.