Larval trematode communities in Radix auricularia and Lymnaea stagnalis in a reservoir system of the Ruhr River

Ana Pérez-del-Olmo,Bernd Sures,Miroslava Soldánová,Christian Selbach,Aneta Kostadinova

doi:10.1186/1756-3305-3-56

Abstract

BackgroundAnalysis of the data available from traditional faunistic approaches to mollusc-trematode systems covering large spatial and/or temporal scales in Europe convinced us that a parasite community approach in well-defined aquatic ecosystems is essential for the substantial advancement of our understanding of the parasite response to anthropogenic pressures in urbanised areas which are typical on a European scale. Here we describe communities of larval trematodes in two lymnaeid species, Radix auricularia and Lymnaea stagnalis in four man-made interconnected reservoirs of the Ruhr River (Germany) focusing on among- and within-reservoir variations in parasite prevalence and component community composition and structure.ResultsThe mature reservoir system on the Ruhr River provides an excellent environment for the development of species-rich and abundant trematode communities in Radix auricularia (12 species) and Lymnaea stagnalis (6 species). The lake-adapted R. auricularia dominated numerically over L. stagnalis and played a major role in the trematode transmission in the reservoir system. Both host-parasite systems were dominated by bird parasites (13 out of 15 species) characteristic for eutrophic water bodies. In addition to snail size, two environmental variables, the oxygen content and pH of the water, were identified as important determinants of the probability of infection. Between-reservoir comparisons indicated an advanced eutrophication at Baldeneysee and Hengsteysee and the small-scale within-reservoir variations of component communities provided evidence that larval trematodes may have reflected spatial bird aggregations (infection 'hot spots'). Two life history groupings of dominant species, the 'cyprinid' and 'anatid' parasites, that depict two aspects of progressive eutrophication in this mature reservoir system, were identified.ConclusionsWe conclude that trematode communities in the lake-adapted R. auricularia are better suited for monitoring the effect of environmental change on host-parasite associations in the reservoir system on the Ruhr River and other similar systems due to the important role of this host in trematode transmission in lakes. Whereas variations in trematode community diversity and abundance may indicate the degree of eutrophication on a larger scale (among reservoirs), the infection rates of the two life history groups of dominant species, the 'cyprinid' and 'anatid' assemblages, may be particularly useful in depicting environmental variability, eutrophication effects and infection 'hot spots' on smaller spatial scales.

Highlights

Analysis of the data available from traditional faunistic approaches to mollusc-trematode systems covering large spatial and/or temporal scales in Europe convinced us that a parasite community approach in welldefined aquatic ecosystems is essential for the substantial advancement of our understanding of the parasite response to anthropogenic pressures in urbanised areas which are typical on a European scale
A parasite community approach would substantially advance our understanding of the parasite diversity in undisturbed freshwater habitats but would be essential for the assessment of parasite response to anthropogenic pressures in urbanised areas which are typical on a European scale
The sample size for the latter species only was strongly correlated with the water temperature at the time of sampling whereas the size of the samples of R. auricularia exhibited a significant association with water pH

Summary

Introduction

Analysis of the data available from traditional faunistic approaches to mollusc-trematode systems covering large spatial and/or temporal scales in Europe convinced us that a parasite community approach in welldefined aquatic ecosystems is essential for the substantial advancement of our understanding of the parasite response to anthropogenic pressures in urbanised areas which are typical on a European scale. Loy & Haas [9] observed no change in the prevalence of larval parasites in Lymnaea stagnalis (L.) over 20 years and Faltýnková & Haas [8] revealed a diverse larval trematode fauna in molluscs (31 species) and the same spectrum of the "typical" for Central Europe species as that observed some 100-150 years ago by La Valette [6] and Lühe [7] Both studies were predominantly carried out on old fishponds existing in the area for centuries and included the ponds of the Aischgrund lowland near Erlangen encompassing a nearly 200 ha natural reserve area hosting an exceptionally rich and abundant avian fauna (more than 250 species, [10]). A parasite community approach would substantially advance our understanding of the parasite diversity in undisturbed freshwater habitats but would be essential for the assessment of parasite response to anthropogenic pressures in urbanised areas which are typical on a European scale

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