Research Interests

Aquatic chemical ecology Molecular ecology
Algae-herbivore interactions Biodiversity
Climate change Food quality
Essential biochemicals Polyunsaturated fatty acids
Stable isotopes in ecology Ecological stoichiometry
Maternal effects Freshwater molluscs
Biogenic volatile organic compounds Chemical communication / infochemicals
Inducible and activated defences  

Current research activities

Diversity loss and trait dynamics in natural plankton communities
This project is part of the DFG-funded priority programme (DynaTrait) and will be conducted in close collaboration with the undefinedDepartment of Aquatic Ecology at the Ludwig-Maximilians-University of Munich. For more detailed information on the priority programme in general and our project in particular, please refer to the undefinedDynaTrait website.

Effect or relevance of repellents for non-target organisms in surface waters
First results of this project will be presented at the undefinedSETAC Europe meeting in Basel, Switzerland, the SETAC-undefinedGLB meeting in Giessen and the DGL meeting in Magdeburg in May, September and October 2014, respectively (This project is funded by the German Federal Environment Agency, UBA).

Biological interactions in microbial mat communities in Salares of the Chilean Andes
This project aims to describe the food web structure and chemical ecology of microbial mats in high-altitude salars of the Chilean Altiplano. It has the specific scientific objectives to I) determine the trophic interactions between the microbial mats and associated invertebrate communities using both analysis of stable carbon and nitrogen isotopes and fatty acid biomarkers, II) determine chemically mediated interactions between microbial mats and associated invertebrate fauna, and III) investigate possible effects of microbial secondary metabolites on invertebrate consumers. (The project is a collaboration with the Unviersidad de Antofagasta, Chile and is funded by the German Federal Ministry for Education and Research, BMBF).

Interactions between consumer and resource diversity
There has been a long debate whether producer diversity is controlled by the presence of consumers (top-down regulation) or by the availability of resources (bottom-up regulation). A yet overlooked steering factor might be the effects of the consumer species diversity on the species diversity of a prey community. Potentially complex interactions between consumers and other environmental factors on the prey community can be easily investigated using periphyton as resource community and freshwater benthic invertebrates as consumers. (Collaboration with Dr. Maria Kahlert from the Swedish University of Agricultural Sciences)

Volatile foraging kairomones in benthic snail-periphyton interactions
Volatile organic compounds (VOCs) can serve as important infochemicals in biofilms of benthic primary producers: VOCs released from both benthic, mat-forming, green algae and diatoms function as food-finding cues that attract benthic herbivores in both marine and freshwater ecosystems. This suggests that VOCs can play a steering role as infochemicals in benthic habitats, as has been established for many organismic interactions in terrestrial ecosystems.

Impacts of algal food quality on Daphnia
In recent years it has been acknowledged that the food quality of freshwater microalgae for herbivorous zooplankton is not only determined by the algae's content of mineral nutrients such as phosphorus, but also by the algae's biochemical composition. In particular, the availability of particular highly unsaturated fatty acids seems to be an important determinant of algal food quality for Daphnia sp. In the current project, I investigate the effects of different polyunsaturated fatty acids supplied with the algal diet to Daphnia sp. on the fitness of these zooplankton herbivores in laboratory experiments.

Adaptations of herbivores to stoichiometric food quality constraints
When faced with a low quality resource (e.g, a stoichiometrically imbalanced diet), consumers utilize different mechanisms to cope with a highly phosphorus- and/or nitrogen-depleted resource. In earlier work (see below), we found that freshwater gastropods increase the nutrient retention during gut passage, i.e., they excrete faecal pellets that are even more depleted in the limiting nutrient than the resource and the consumers' body tissue. Furthermore, the snails are increasing their biomass-specific consumption rates (on a diet low in essential compounds) in order to increase the uptake of the limiting nutrient(s). Currently, I investigate these and other mechanisms of herbivores to adapt to spatially and temporally fluctuating resource nutrient contents.

The ecological function of volatile aldehydes (oxylipins) in marine and freshwater benthic ecosystems
Volatile aldehydes (or oxylipins) released from damaged diatom cells have been shown to dramatically lower the hatching success of herbivorous copepods and therefore are considered to form an activated defence strategy of the diatoms versus herbivores. Alternatively, such substances might also serve as infochemicals, especially in biofilms of benthic algae and cyanobacteria. In this project, I investigate the interactions between oxylipins released by benthic diatoms and green algae and herbivorous gastropod grazers. (Collaboration with Dr. Valerio Zupo from the Benthic Ecology Group at Stazione Zoologica die Napoli, Italy)

Ecology of the invasive mysid shrimp Limnomysis benedeni
As most other freshwater invasive species in Europe, the mysid Limnomysis benedeni originates in the ponto-caspian region. Recently, it has rapidly spread out through the large European river systems and adjacent lakes. Despite this rapid spread of L. benedeni in Europe during the last years, there is only very little knowledge about the potential consequences of the invasion of this species on the native ecosystems. Without knowledge on the behaviour and feeding strategies of L. benedeni, its impact on native species can not be estimated. Therefore, I investigate the feeding ecology of L. benedeni in the bayous of the Lower Rhine, where this species has recently invaded and since developed mass abundances.

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