HR: 10:30h
AN: NB32E-01 [Abstracts]
TI: Top-down Control of Stream Food Webs: Indirect Effects by Changed Behaviour and Species Interactions
AU: * Winkelmann, C
EM: Carola.Winkelmann@mailbox.tu-dresden.de
AF: Dresden University of Technology, Institute of Hydrobiology, Dresden, 01062 Germany
AU: Petzoldt, T
EM: petzoldt@Rcs1.urz.tu-dresden.de
AF: Dresden University of Technology, Institute of Hydrobiology, Dresden, 01062 Germany
AU: Koop, J H
EM: koop @bafg.de
AF: Bundesanstalt fuer Gewaesserkunde, Postfach 200253, Koblenz, 56002 Germany
AU: Benndorf, J
EM: bennd@rcs.urz.tu-dresden.de
AF: Dresden University of Technology, Institute of Hydrobiology, Dresden, 01062 Germany
AB:
Predators may directly control stream food webs by consuming invertebrates. But sub lethal effects on prey such as change of
activity rhythm or feeding behaviour may lead to indirect effects of predation on other species. Thus, predators may strongly effect invertebrate community structure. The aim of a currently running paired ecosystem experiment is to detect changes of
species interaction induced by benthivorous gudgeon (Gobio gobio). For this purpose we link the measurement of physiological
fitness parameters to the observation of behavioural changes. Preliminary studies indicated a top-down control of the drift
activity of Baetis larvae, while a bottom-up effect could not be observed. The presence of benthivorous gudgeon led to a
significantly changed species composition of the invertebrate drift and reduced drift activity of Baetis larvae compared to
the fish free control. The diurnal drift pattern of Baetis larvae with a nocturnal peak was observed both in the control and
fish reaches. Thus benthivorous gudgeon controls the drift behaviour in a similar way as known for drift-feeding trout. The
content of triglycerides and glycogen did not differ between the drifting and not-drifting individuals. Therefore their
energetic status does not seem to control drift the activity of Baetis larvae.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly