Understanding the effect of nutrients on the abundance of cyanobacteria in freshwater lakes provides important knowledge for restoring and sustaining a safe, clean water supply for multiple uses.Triathlon competitors swimming in a lake

Models published this week in the Journal of Applied Ecology allow river basin managers to set nutrient targets to sustain recreational services and provide different levels of precaution that can be chosen dependent on the importance of the ecosystem services provided at a site. 

Dr Laurence Carvalho, a freshwater ecologist at the Centre for Ecology & Hydrology and the lead author on the paper said, “This is the first large-scale study to quantify the relationship between nutrients and the actual abundance of cyanobacteria.  Importantly it examines the likelihood of exceeding health thresholds set for recreational waters by the World Health Organisation, explicitly linking nutrient targets to the potential use of freshwaters by the public.”

It is widely recognised that nutrient enrichment of freshwaters leads to an increased frequency and more severe incidents of algal blooms, particularly of toxic cyanobacteria.  This has consequent effects on multiple uses of lakes and reservoirs for recreation, drinking and spray irrigation. 

In the study a novel statistical approach called quantile regression was used to model the maximum abundance of cyanobacteria for a given level of nutrients in a lake, and also the changing probability that these harmful algae exceed World Health Organisation guideline values for recreational waters, with future changes in nutrient levels.

The models are based on measured data from more than 800 European lakes collated as part of the WISER (Water bodies in Europe: integrative systems to assess ecological status and recovery) Project. 

The analysis was carried out whilst Dr Carvalho was on a secondment to the European Commission’s Joint Research Centre where he worked on the PEER project to map ecosystem services at a European scale.

Additional information

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

WISER website

PEER PRESS project

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UK Lake Restoration - CEH case studies

 

 

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