SNIFFS: Steering role of infochemicals for food chain function and structure

• Research unit: EU RFP
• Project number: 97.0040

Key words (English)

Alpine lake; food chain; kairomones; Daphnia; fish

Alternative project number (English)

EU project number: ENV4-CT97-0402

Research programs (English)

EU-programme: 4. Frame Research Programme - 3.1 Environment

Short description (English)

See abstract

Partners and International Organizations (English)

Netherlands Institute of Ecology- centre for Limnology (NL), Max-Planck-Institute for Limnology (D), Institute for Organic Chemistry, University of Hamburg (D)

Abstract (English)

The principal aim of the project is to describe the influence of kairomones excreted by fish and zooplankton on their food organisms (zooplankton and phytoplankton) as well on the transfer of organic matter in a simplified food chain. Therefore we describe quantitatively the transfer of matter in a simplified tritrophic food chain (algae ® herbivorous zooplankton ® planktivorous fish) of two contrasting aquatic ecosystems under natural conditions. Both ecosystems belong to the Rhine catchment: a mesothrophic lowland lake in The Netherlands (lake Maarsseveen), and an oligothrophic Alpine lake in Switzerland (the Aroser Obersee). In this abstract we report on the Swiss investigations in the Obersee.
The last year of the project we concentrated on field experiments to test hypothesis derived from our earlier investigations. An in situ grazing experiment showed that Daphnia eats algea at all depths. An enclosure experiment showed that daphnids migrate in the Aroser Obersee also in the absence of fish kairomones. We investigated the role of ultraviolet radiation UVR on the Daphnia survival, hypothesising that UVR might be a key factor in the Diel Vertical Migration of Daphnia in this alpine lake. We found during a life-history experiment, done in the lake, that Daphnia survival was significant reduced in the upper layer of the lake.
Together with the University of Hamburg (partner 4) a life-history experiment was conducted in order to test if modified amino sugars that were recently found to induce a phototactic reaction in brine shrimp larvae, Artemia salina, are also relevant for Daphnia life histories. Our results showed that the sugars did not show the same life history changes as in the fish kairomone water. From which we conclude that these sugars are not the fish factor that changes Daphnia life histories.
The effect of temperature was investigated on the life histories of migrating and non-migrating clones both from the Obersee and Untersee (which are connected). Our results show that temperature influence stronger the juvenile development compared to the growth of the adults.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0040