Managing Baltic nutrients in relation to cyanobacterial blooms: what should we aim for?

Project leader


Funding source

Formas - The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning

Project Details

Start date: 01/01/2009
End date: 31/12/2012
Funding: 14000000 SEK


Cyanobacterial summer blooms are a main problem of Baltic Sea eutrophication, and a common argument against reducing its nitrogen load. Dense surface accumulations can cover the sea surface, make bathing impossible and harm coastal recreation and tourism. Blooms are toxic and increase Baltic eutrophication by fixing 200-400 kton nitrogen/yr. They are natural to the Baltic, and the nitrogen they fix likely supports Baltic fish yield. To eliminate blooms would be costly, and could greatly change the Baltic ecosystem and reduce fish yield. Studies will be made both in the open sea and the coastal area and use the long time series (≤ 33 yrs) of nutrients, phyto- and zooplankton (≥20 times/yr) from Stockholm University?s ecological research, and cover: 1. factors causing and regulating blooms, 2. prediction of bloom severity, 3. ecosystem effects of blooms, especially for fish food and fish larvae, 4. fate of the nitrogen fixed by blooms ? where does it go, how quickly is it lost by conversion to nitrogen gas? 5. cost-benefit analysis for society of bloom reduction. The main aim of the study is to help managers, from HELCOM to local authorities, to predict the effects of measures to reduce nutrient concentrations in the Baltic, to strike the right balance between reduction of nitrogen and phosphorus, and to minimise noxious blooms, without changing the nature of the Baltic Ecosystem, or overly reducing its fish production.

Last updated on 2017-24-03 at 12:58