Scientific challenge

Blooms of algae in freshwaters can produce potent toxins, potentially making water bodies unsafe for recreational activities and restricting their access to the public and their suitability as a source of water for drinking and irrigation.

Blooms are often produced by cyanobacteria, also known as blue-green algae. They typically colour the water bright green and can form a surface scum along shorelines. Cyanobacteria produce toxins which cause a range of health problems, from minor skin irritations to severe stomach upsets, and can even lead to death. The World Health Organisation has established guideline values of cyanotoxins and cyanobacterial cell densities for recreational use and for drinking waters.

Providing the evidence base

Algae can bloom in waters that have been polluted with high levels of nutrients, such as phosphorus. At CEH we have undertaken research to quantify the effect of nutrients on cyanobacteria abundance. Our research (Carvalho et al. 2013) has provided evidence for setting management targets for restoring and sustaining a safe, clean water supply for recreation and other users.

Climate Change Impacts

Using a continental-scale dataset of European lakes , we have examined how nutrient pollution interacts with climatic stressors, such as high temperatures, low rainfall and extreme weather events and have shown how different lake types across Europe have different sensitivities to nutrients and climatic variables (Richardson et al., 2018). We can use these multiple stressor empirical models to predict risks of developing harmful algal blooms.

Future challenges

In the GloboLakes Project, we are examining satellite earth observation data to examine the distribution of harmful algal blooms in 1000 of the world's largest lakes globally and how climate, land-use and population in their catchments explain their abundance.  We can use these data to assess global health risks and risks to water security.

Related projects, outputs & resources

​Recent papers

Richardson J., Miller C., Maberly S.C., Taylor P., Globevnik L., Hunter P.,  Jeppesen E., Mischke U., Moe J., Pasztaleniec A., Søndergaard M. and Carvalho L., 2018. Effects of multiple stressors on cyanobacteria biovolume varies with lake type. Global Change Biology, 24, 5044-5055

Carvalho et al, 2013. Sustaining recreational quality of European lakes: minimising the health risks from algal blooms through phosphorus control. Journal of Applied Ecology, 50, 315-323.

Elliott, J A 2012. Is the future blue-green? A review of the current model predictions of how climate change could affect pelagic freshwater Cyanobacteria. Water Research, 46, 1364-1371.



Principal Investigator