Institut für Evolution und Ökologie

Tom Zörrer

 

 

BSc candidate

78818  tom.zoerrer(@)student.uni-tuebingen.de

room 019, basement floor

Aim of the study

Based on a stone crayfish (Austropotamobius torrentium) monitoring carried out in 2021 in the Schönbuch area, differences in the abundances of stone crayfish were detected. In the past, populations of stone crayfishs were found in the streams Weilerbach, Rosenbach and Himbach. However, at the time of the monitoring in 2021, the presence of stone crayfish was only detected in the Himbach. After this monitoring, the question of the occurrence and possible fluctuations in population sizes of the amphipod Gammarus fossarum arose. Gammarus fossarum is a typical inhabitant of rivers and streams that is very sensitive to environmental factors and pollutants and has large population sizes. Therefore, Gammarus fossarum is very suitable as a test organism for the present study. First, the population density is quantified at selected sampling sites of the Weilerbach, Rosenbach and Himbach streams near Tübingen. This is followed by passive monitoring with Gammarus fossarum. In the collected individuals, oxidative stress will be examined using the FOX assay, and the fecundity index of breeding females will be calculated. This is followed by an active monitoring, where individuals are taken from the well-populated control site and exposed to all sampling sites for several weeks. Subsequently, the oxidative stress level and the fecundity index will also be determined. In addition, the mortality rate of the transplanted individuals will be documented. Furthermore, external factors such as water discharges will be documented, which will be also correlated with population density. This should provide information on the condition of streams and the health of Gammarus fossarum and, if possible, allow conclusions to be drawn about possible factors for the decline in the stone crayfish population.