Limnomysis benedeni and other neozoa in Lake Constance
In summer 2006, the Ponto-Caspian mysid L. benedeni invaded Lake Constance, colonized the place of discovery very fast and spread up over the whole lake. Although the mysid is common in the Rhine and Danube river system, only little is known about the ecology of the mysid. Especially the population dynamics and the impact of the mysid on the ecosystem is part of our research. The amphipod Crangonyx pseudogracilis and the mysid Katamysis warpachowskyi were first found in 2008 and 2009 and observed since then.
Ecology of mixotrophic algae in Lake Constance
In Lake Constance the share of mixotrophic algae in phytoplankton biomass has been increasing during the last years. Apparently mixotrophy (a combination of phototrophic and heterotrophic nutrition) is a successful strategy of gaining required nutrients. This study will place emphasis on the ecology of the mixotrophs. We will monitor the annual changes in mixotrophy in Lake Constance by applying inter alia the method of CARD-FISH and perform different short-term grazing experiments under varying external conditions.
CRC 454 Subproject A1: Littoral macroinvertebrate communities of Lake Constance (funding till July 2007)
The main research objective of this project is to analyze the abiotic environmental factors (e.g., hydrodynamics, substrate properties, substrate stability) and the biotic interactions (e.g., resource limitation, competition, predation, ecological engineering) that influence the littoral macrozoobenthos communities of Lake Constance. In doing so, we combine experimentation at various levels (field, mesocosm and laboratory experiments) with data collection in the field. Our scheduled work takes into account that the littoral macroinvertebrate communities of Lake Constance are presently being confronted with new invading species. In summer 2003, the Ponto-Caspian gammarid Dikerogammarus villosus and the Asian clam Corbicula fluminea were first observed in Lake Constance.
- The Dreissena-biodeposition based food web
This may be a case of omnivory in a detritus based food web, with Gammarus and chironomids competing for a shared resource and Gammarus preying on chironomids. Our research objective is to study the interactions involved in this food web (e.g., seasonal patterns of biodeposition, food quality of deposited material for Gammarus, influence of Gammarus on chironomid densities, influence of enrichment on the relative densities of both main taxa). During this work, we will always keep in mind that the invasion by Dikerogammarus may severely disturb the Dreissena-biodeposition based community.
- Possible influences of Corbicula fluminea on the littoral community
The invasive clam Corbicula fluminea may affect the littoral invertebrate communities by competing with Dreissena for space and/or suspended food. Alternatively, Corbicula may act as a physical ecosystem engineer by providing additional settling places for Dreissena on soft substrates. Several scenarios are conceivable. We will test these scenarios in laboratory and field experiments.
Lake Constance is among the largest lakes in central Europe and represents the most important drinking water reservoir in south-western Germany. In total, about 4 million people depend on this lake in terms of their drinking water supply and considerable efforts have been carried out to protect the high water quality of the lake. Within this context the BodenseeOnline-project aims on the establishment of a modern water quality management system for Lake Constance based on the application of complex ecosystem models. The core of this system constitutes on a 3D hydrodynamic model (ELCOM) which is coupled to an ecological model (CAEDYM). This system is going to be used for predicting thermal stratification, dominant current fields and distribution and dynamics of ecological variables (e.g. phytoplankton) or incidentally introduced contaminants. The focus of our work in Constance within BodenseeOnline is focused on the development and application of the ecological model and extensive sensitivity studies using a 1D model system (DYRESM-CAEDYM)