Ecological analysis of trematodes (trematoda) of marsh frog pelophylax ridibundus (ranidae, anura) from various habitats of the national park «samarskaya luka» (Russia)

Abstract

A comparative analysis of the trematode fauna of the marsh frog Pelophylax ridibundus from different habitats of the National Park «Samarskaya Luka» is given. It is based on the authors' own materials collected in 1998-2001 on three locations: on the coast of the Volga channel, floodplain lakes and nearby islands. Twenty-two trematode species were found. Differences in the composition of trematodes and the nature of infestation of amphibians from different biotopes have been revealed. It has been established that the diversity of trematodes and their infectivity are higher in amphibians in floodplain lakes with relatively constant environmental conditions. Frogs from river coast habitats with dynamic environmental conditions are less infected with the same diversity of species. Amphibians of isolated island habitats are characterised by relatively small number of trematode species and a low level of helminth invasion. The causes of differences in amphibian infestation by trematodes in different biotopes are complex. Diversity, high abundance of mollusks and arthropods (intermediate hosts) cause a high level of infestation of frogs with sexually mature flukes, transmitted through food chains. The high density of the amphibians themselves, and, accordingly, of the predators batrachophages, leads to intensive infestation of frogs by larval stages of trematodes. A literature review of the data on the influence of abiotic and biotic factors of the environment on amphibian trematode is given. The formation of the trematode fauna of frogs is influenced by a number of environmental factors acting in the aggregate: the hydrological regime of the reservoir, the diversity and density of populations of intermediate, reservoir and definitive hosts of trematodes in the biocoenosis.