Phytoplankton and Water Quality Characterization: Experiences from the Swedish Large Lakes Mälaren, Hjälmaren, Vättern and Vänern

Abstract

Phytoplankton and environmental variables have been monitored in the large Swedish lakes Malaren, Hjalmaren, Vattern and Vanern since the 1960s. Measures to reduce phosphorus input and industrial waste products were taken during the 1970s. The phosphorus loading was then reduced by 90-95% resulting in a halving of the phosphorus concentrations in the most affected basins. The phytoplankton community reacted rapidly with decreased biomasses of cyanobacteria in summer as well as decreased biomasses of spring diatoms and cryptophycean flagellates. Other reactions were a contracted period of waterbloom, an increased taxon richness, an increased evenness in the biomass over the growth season, and a change in the species size structure within the phytoplankton community. Furthermore, the species richness in the large lakes is compared in relation to lake characteristics. A presentation of the occurrence of toxic cyanobacteria in the lakes is also given. Maximum-minimum values of 13-0.1 mug microcystin L-1 are established in connection with water-blooms in Hjalmaren and Malaren. The use of phytoplankton as a monitoring variable to detect water-quality changes is outlined and assessment criteria are presented.

Published in

AMBIO: A Journal of the Human Environment
2001, Volume: 30, number: 8, pages: 529-537 Publisher: SPRINGER

SLU Authors

• Willén, Eva

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Oceanography, Hydrology, Water Resources
Environmental Sciences


Publication identifier

DOI: https://doi.org/10.1579/0044-7447-30.8.529

Permanent link to this page (URI)

https://res.slu.se/id/publ/131617