Aquatic Sciences Meeting, Albuquerque 2001

CS01 Air-Water Interactions

Date: Wednesday, February 14, 2001, Time: 2:45:00 PM

Location: San Miguel

Carstensen, J, , National Environmental Research Institute, Roskilde, Denmark, jac@dmu.dk

Markager, S, , National Environmental Research Institute, Roskilde, Denmark, ssm@dmu.dk

Henriksen, P, , National Environmental Research Institute, Roskilde, Denmark, pet@dmu.dk

Frequency analysis of algae blooms in Kattegat

Algae blooms occur frequently during the summer period in Kattegat, an estuarine area which limits the Baltic Sea to the North Sea. Recent estimates suggest that about 60 % of the nitrogen loading comes from the atmosphere during the summer period and the overall goal was to link algae blooms with nutrient input events using frequency analysis techniques. Measurements of chlorophyll, primary production and phytoplankton biomass from the Swedish and Danish national monitoring programs (1989-99) have been analyzed to determine values with a 10-year return period, i.e. the values that statistically will be exceeded once every 10 years. The analysis has revealed large spatial variations where the shallow western part of Kattegat is more frequently exposed to algae bloom of greater magnitude than the deeper eastern part. In addition, summer algae blooms were often dominated by single opportunistic species. The analysis can be applied to longer time periods to detect changes in frequency and magnitude of algae blooms.

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Aquatic Sciences Meeting, Albuquerque 2001

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