Faculty of Biology
PhD thesis: The influence of the european beaver (Castor fiber) on habitats and the invertebrate fauna of streams of the lower mountain area and their meadows
The goal of the PhD project is to quantify and qualify the influence of beaver dams on the biodiversity of the water-meadow-ecosystem. The study focusses on small streams in the lower mountain area in which a strong dispersion of beavers is expected as well as the species group of invertebrates which is commonly used for the evaluation of waters and the description of guiding principles.
Methods: the water sections populated by beavers are characterised in relation to substrate, flow velocity, temperature and oxygen content. On this basis, the species community in beaver-induced habitats, particularly beaver dams, is examined. The overarching goal is to quantify the changes within the invertebrate community of larger water sections through the activities of beavers. In addition to established study methods we apply new techniques including aerial photography and the examination of beaver dams with a vacuum sampler which was especially developed for the study ("Beaver Dam Vacuum Sampler"). To this end, streams of the lower mountain area in the northern Eifel were chosen as the study area. In spring 2018 we took first aerial pictures and sampled 16 beaver dams with the vacuum sampler.
First results: In order to gain a first insight, the fauna of the order Trichoptera and Coleoptera of two beaver dams were chosen. The Trichoptera community mainly consists of typical representatives of low order streams of the low mountain area such as Agapetus fuscipes, Halesus radiatus, Diplectrona felix and Philopotamus montanus. On the contrary, the Coleoptera fauna was more diverse and includes species that indicate running waters (Elodes minuta), still waters (Hydrochus angustatus), terrestrial (Octotemnus glabriculus) and transitional (Dianous coerulescens) habitats.