@phdthesis{Tluste2023, author = {Tluste, Claudia}, title = {Population ecology of the Roman snail (Helix pomatia L. 1758) in Cottbus, Brandenburg}, doi = {10.26127/BTUOpen-6650}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-66506}, school = {BTU Cottbus - Senftenberg}, year = {2023}, abstract = {By the year 2539 almost 75\% of all freshwater mollusc species within Europe will be lost. The transformation of natural ecosystems, the extension of infrastructure, as well as agriculture are the main threats. The Roman snail (Helix pomatia L. 1758) has been part of human culture for centuries and is protected by law as an endangered species in several regions, and at the same time regarded and treated as a pest, making the conservation of this species difficult. The aim of this thesis was to create a better understanding of H. pomatia and its functional role within the ecosystem. Eight subpopulations were studied regarding its role within the food web, the use of empty shells as a mircohabitat and its influence on vegetation by showing food preferences. The latter, due to the fact, that a strong predation pressure can minimize habitats, which leads to higher pressure on the local vegetation and a limited possibility of shells being used as a microhabitat. First, the relationships between H. pomatia individuals, subpopulations and their predators were analysed. The total number and percentage of shells that showed external attack marks by predators (32\%) and internal utilization marks by Diptera pupae (45\%) were analysed and correlated to morphometric traits of shells. Signs of external attack and internal utilization marks were positively correlated (R = 0.79; P = 0.020). External attacks were more regular in larger shells and internal utilization was more frequent in shells with higher body density. The second chapter focuses on the shells of H. pomatia and their value as microhabitat for shell adopters in different vegetation forms and during two sample periods. Out of 618 collected shells, 91.4 \% were inhabited and the average was 1.5 time higher in summer, than in autumn. The number of shell adopters per shell was 1.5 times higher in herbaceous vegetation, than in areas dominated by trees. Shell width (P = 0.008), but not shell height (P = 0.078) had a significant higher influence. Finally, food preferences of H. pomatia were analysed, showing a pronounced preference for Urtica dioica (35\% of all 697 feeding interactions) and plant litter (44\%). Only 27 out of 143 available plant species were eaten and a literature review confirmed U. dioica as a food plant for 19 other terrestrial snail species. The width and height of the snail shells were related to the feeding height as smaller, juvenile snails fed higher in vegetation (384mm ± 327mm) compared to adult individuals (68mm ± 194mm) (P<0.001). These results highlight the importance of H. pomatia in the studied ecosystem. H. pomatia is an important food source for predators and host for parasitoids, the shells offer habitat and refuge for soil organisms and as a relatively specialized herbivore and decomposer H. pomatia contributes to herbivory and nutrient cycling in ecosystems. Hopefully this study may help to motivate future conservation efforts.}, subject = {Helix pomatia; Food web; Ecology; Soil; Malacology; Weinbergschnecke; Nahrungskette; {\"O}kologie; Boden; Malakologie; Weinbergschnecke; Weichtierkunde; {\"O}kosystemforschung}, language = {en} }