van Gool, E. NIOO-Centre for Limnology, gool@cl.nioo.knaw.nl
Ringelberg, J. University of Amsterdam, ringelberg@cl.nioo.knaw.nl

 
ESTIMATES ON EFFECTIVE KAIROMONE CONCENTRATION IN THE FIELD MAY PREDICT DIEL VERTICAL MIGRATION
 
Laboratory experiments have emphasized the importance of predator associated chemicals (kairomones) for adaptive changes in morphology, life history, and behaviour. However, the quantitative effects of these kairomones on the responses of prey animals in the field is difficult to assess and has got little attention. An important adaptive behaviour of planktonic animals to prevent predation by visual hunting fish is diel vertical migration (DVM). Extensive laboratory experiments have revealed the properties of light-induced behaviour underlying DVM. For the induction of this behaviour fish kairomones are important. We developed a bioassay based on aspects of light-induced behaviour to quantify the effective concentration of fish kairomone in a lake (Lake Maarsseveen, The Netherlands). At the same time, estimates of fish biomass were made and DVM of Daphnia was studied. We found that the strength of the induction of light-induced behaviour increased and decreased in concert with the amplitude of migration. We also found a relation between this strength and biomass of 0+ perch. However, effects were confined to water form the epilimnion, and were absent in the fish-free hypolimnion.
 
Day: Thursday, Feb. 4
Time: 12:00 - 12:15pm
Location: Hilton of Santa Fe
 
Code: SS16TH1200H