CS16 Harmful Algal Blooms
Date: Wednesday, June 12, 2002
Time: 2:30:00 PM
Location: Sidney
 
VerspagenJ, University of Amsterdam, Amsterdam, Netherlands, jolanda.verspagen@science.uva.nl
Snelder, E, , University of Amsterdam, Amsterdam, Netherlands, eveline.snelder@science.uva.nl
Visser, P, M, University of Amsterdam, Amsterdam, Netherlands, petra.visser@science.uva.nl
Mur, L, R, University of Amsterdam, Amsterdam, Netherlands, luuc.mur@science.uva.nl
 
POPULATION DYNAMICS OF MICROCYSTIS IN WATER AND SEDIMENT IN LAKE VOLKERAK (THE NETHERLANDS)
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The toxin producing, bloom-forming cyanobacterium Microcystis overwinters on the sediment. The surviving benthic population is thought to provide the inoculum for the pelagic population in spring. In this study, size and importance of the benthic and pelagic inoculum are compared. A 2-year field study was carried out in which water and sediments of Lake Volkerak were sampled every 2 weeks, to follow dynamics in water and sediment. Traps were placed in the lake to study the up- and downward movements of colonies. Also, the buoyancy state of colonies was determined on benthic colonies from the sediment, together with measurements on gas vesicle volume and intracellular carbohydrate content, to find out if benthic inoculation was triggered by changes in buoyancy. From the results, we could conclude that the benthic inoculum was much lower than the pelagic inoculum in Lake Volkerak and that the benthic inoculum was not triggered by changes in buoyancy.