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Seminar by Dr. Piet Spaak: water fleas vs. cyanobacteria

When:Th 19-05-2016 16:00 - 17:00
Where:Linnaeusborg - Nijenborgh 7, room 517.20571 (Blue Room) - Free Admission

Piet Spaak
Alumnus of the University of Groningen (1988 MA Biology), Dr. Piet Spaak, heads the aquatic ecology department of Eawag, Zürich. He is a specialist in resurrection ecology, an evolutionary biology technique in which dormant eggs from lake sediments, but also pathogens - parasites in aquatic ecosystems, are hatched to study as they existed decades ago. His main research objects are water fleas. He researches the way water fleas adjust to their changing environment, as they are excellent predictors of water pollution.

A team led by Piet Spaak showed that – contrary to the assumptions of traditional conservation science – evolutionary processes can often produce marked changes and adaptations in species within a few generations. In this study, 50yearold resting stages of water fleas (Daphnia) were retrieved from Greifensee sediment cores, and viable eggs were then hatched in the laboratory. Compared with more recent specimens, these water fleas were significantly more resistant to the elevated lead concentrations which prevailed in the 1960s.

Seminar Dr. Piet Spaak
Seminar Dr. Piet Spaak

The causes and consequences of parasite epidemics in a Daphnia hybrid species complex: the role of cyanobacteria
The annual succession of plankton in temperate lakes is strongly triggered by climatic cues. This succession, however, is a rough framework and the underlying inter- and intra-specific dynamics are still controversial and unforeseen links among different community members might exist. Recently, Piet Spaak and his team discovered that there is a relationship between the occurrence of cyanobacteria and Caullerya epidemics in Greifensee using time-series analysis. This led to a series of studies in which they investigate the effect of cyanobacteria on Daphnia and how they interfere with parasites. Understanding long-term water flea and cyanobacterial community dynamics will help predict the effects of environmental changes on ecosystems and potentially lead to better management practices in freshwater bodies.

Eawag is the Swiss Federal Institute of Aquatic Science and Technology and is part of the ETH Domain. Eawag is concerned with concepts and technologies for dealing sustainably with water bodies and with water as a resource. In collaboration with universities, other research institutions, public bodies, industry and non-governmental organisations, Eawag works to harmonise ecological, economic and social interests in respect of water usage.

This seminar is organized in collaboration with the Ubbo Emmius Fund, Eawag and GELIFES.