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

In the pelagic of lakes, infochemicals, like kairomones and allomones, change morphology, life history or behaviour of autotrophs and herbivores. This leads to changed population dynamics and predator prey - relations, and, consequently, foodweb structure and transport of matter is affected. Herbivores, like the cladoceran Daphnia, perceive allomones produced by algae but Daphnia also produce a kairomone that alters edibility of algae. Invertebrate and vertebrate predators mediate kairomones that cause predator-specific changes in the prey. The effects are clone specific. A conspicuous behavioural change is diel vertical migration. Although a succesful strategy, costs are high and thus amplitude is variable. An overshoot of adaptive needs occurs due to physiological and behavioural constrains but more often a compromise seems to be realised between a lowered birth rate and a higher predation rate. In some clones, an accent is on life history changes. Depending on the intensity of selection factors, like predation and food availability, genotypes are weeded from the population within a short time. With examples from a ten year long study in Lake Maarsseveen (The Netherlands), the happenings during a seasonal period of a few weeks will be illustrated.
Day: Thursday, Feb. 4
Time: 12:15 - 12:30pm
Location: Hilton of Santa Fe
Code: SS16TH1215H