
Forschungsinstitut für Ökosystemanalyse und -bewertung gaiac e.V.
Masterarbeit gaiac: periphyton testing
In chemical risk assessment, microalgae like Raphidocelis subcapitata are tested as representatives for primary producers. However, this planktonic species might be only of little relevance for lotic ecosystems (streams) where mostly benthic algae communities are present. They consist of taxa with different needs regarding environmental conditions and thus also different physiological characteristics. As already shown in several studies for aquatic invertebrates, a similar ecotoxicological response of planktonic and benthic communities and species has not necessarily to be expected.
Thus, to better address the effects of chemical contaminants on benthic algal communities, gaiac is currently developing a test system with benthic single species as well as artificial communities (combinations of single species). This work should be finalised and brought into use with a plant protection product.
Furthermore, a test system with a natural periphyton community exposed under defined laboratory conditions is already established.
In all test systems, the development of algal biomass and the composition of the three main algal classes green algae, blue-green algae and diatoms are monitored fluorometrically as chlorophyll-a. Furthermore, effects on the species are addressed by cell-counting using a microscope at specific timepoints
As part of the master’s thesis, the test system for the single species and artificial communities developed so far is to be validated and tested with a pesticide. Here, important parameters for the implementation of the test system (number of replicates, test duration, endpoints) are to be derived using statistical methods. Furthermore, possible differences in the sensitivity between the single species, artificial algal combinations and the natural periphyton community should be addressed.
The work to date has been carried out in close cooperation with Bayer AG which is to continue.
The work can be carried out from March 2025. Location of performance is gaiac research institute.
Contact:
Silke Claßen
classen@gaiac-eco.de
Um sich für diesen Job zu bewerben, sende deine Unterlagen per E-Mail an classen@gaiac-eco.de