Project properties
Title Harmful cyanobacterial blooms: Effect of elevated temperatures on the Daphnia-Microcystis interaction
Group Aquatic Ecology and Water Quality Management Group
Project type thesis
Credits 36
Supervisor(s) Miquel Lurling, Els Faassen
Examiner(s) Miquel Lurling
Contact info Plankton Ecology: miquel.lurling@wur.nl
Aquatic Ecology Edwin Peeters 0317-483899 Edwin.peeters@wur.nl
Water Quality Management Bart Koelmans 0317-483201, Room 411, Bart.Koelmans@wur.nl
Begin date 2014/08/01
End date 2015/02/01
Description Future climate scenarios predict higher temperatures that consequently may affect growth and activity of organisms, timing of events and influence population dynamics. In freshwater systems, warming is expected to act in synergy with eutrophication aggravating nuisance cyanobacteria blooms. The cyanobacteria blooms can be hazardous to animals because many cyanobacteria are capable of producing potent toxins. Recently, we discovered that the production of the most widespread occurring cyanobacterial toxins –microcystins- in the most abundant cyanobacterium Microcystis is reduced at elevated temperatures. However, what the consequences of the lower toxin quota are for the important cladoceran grazer Daphnia is unknown. When Daphnia are capable of suppressing the Microcystis founder population, formation of blooms might be prevented or delayed. If the founder population kills or strongly inhibits the Daphnia, blooms may develop, but only in conditions where sufficient resources are available to fuel the blooms. In this project, the student will culture several Microcystis aeruginosa strains and Daphnia species at different temperatures (18o, 22o, 26o, 30o). The animals will be exposed to varying mixtures of the cyanobacteria and a good food green algae (Scenedesmus); microcystin concentration will be measured. Survival, feeding, growth and reproduction of the animals will be determined. In a second series, Daphnia, Microcystis and Scenedesmus will be cultured in water varying in nutrient content and at different temperatures. The hypothesis will be tested that higher nutrient status will stimulate Microcystis, but that at elevated temperatures the tipping point of cyanobacteria dominance will be shifted too.
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