The community composition and structure of helminths of Pipistrellus pipistrellus (Schreber, 1774) from two widely separated Spanish localities, El Saler (n = 42) and the San Pedro pothole (n = 34), were determined and compared. Five species of trematodes, Plagiorchis (Plagiorchis) sp., Lecithodendrium (Lecithodendrium) linstowi Dollfus, 1931, Prosthodendrium (Prosthodendrium) sp., Pycnoporus heteroporus (Dujardin, 1845) and Parabascus semisquamosus (Braun, 1900), and one species of cestode, Hymenolepis pipistrelli López-Neyra, 1941, were found. The two bat populations harboured the same helminth species and showed the same trematode dominance, but the most important differences between the two helminth community structures were attributable to L. (L.) linstowi and H. pipistrelli. The mean species richness in the two localities was not significantly different. The mean number of helminth species per infected bat, mean infracommunity abundance and mean infracommunity diversity showed significant differences between both localities. The number of helminths per bat in both populations displayed an aggregated distribution. Results indicate that the different characteristics of the P. pipistrellus foraging area in both localities are important in determining the composition and structure of helminth communities in this bat species. This is the first study of a Palaearctic bat helminth community.
The need for more long-term studies on helminth communities was addressed by examining changes in composition and diversity of the intestinal helminth component and infracommunities in eels of a small isolated river over 12 years. Examination of samples over one summer season indicated that single samples were representative of community richness in that year. In 1985 the community was species poor (1 species only) and with zero diversity, but by 1996 it comprised six species and all parameters at both levels indicated that it was the richest community yet reported from eels. This overall increase in diversity was not regular or uniform from year to year: rather, the general trend could be reversed in any year(s) and variation between years was considerable. The occurrence of many species was erratic and the identity of the dominant species varied between years. The helminth species that colonised the river contributed to helminth species richness and had an impact on community diversity. It is believed that the overall increase in diversity reflects the changing conditions in the habitat and catchment, but the erratic fluctuations in parameters may reflect the size of the river and the absence of any rescue effects. The findings are compared with the few other long-term studies and it is suggested that the extent of the variation over long periods makes it very difficult to use helminths as indicators of other than general environmental changes or to detect short-term changes due to such specific sources as pollution.