During 11 years (since 1983) populational and parasitological surveys of coexisting populations of Littorina saxatilis and L. obtusata were carried out at the west spit of the South Inlet of the Ryazhkov Island (Kandalaksha Bay of the White Sea). Ten species of trematodes were found. Species list of trematode parasites was identical for two host species. Microphallus piriformes was the commonesi trematode species (infection prevalence by this parasite reached 51.5 %). Levels of infection by any other species did not exceed several percent. It was shown that species composition of double infections was simply a reflection of the infection prevalence by the corresponding trematodes. So, the commonest species M. piriformes was found in double infections with all other trematodes. In most cases detailed analysis of coincidence of different trematodes in double infections has not revealed any deviation from the random pattern. The only exception to this were double infections by M. piriformes and M. pygmaeus, and by the pair of Himasthla sp. and immature sporocysts of microphallids of the "pygmaeus" group, which were rarer than expected. Deviation from the random pattern (tested by Chi-square statistics) was significant in 1983 and 1984 (for M. piriformes-M. pygmaeus combination) and in 1994 (for the second pair of parasites). Double infections by Himasthla sp. with mature microphallids of the "pygmaeus" group did not differ in frequency from the expected values. Triple infection were very rare. However, the observed frequencies of triple infections exceeded the expected values by 1-2 orders of magnitude. Above described peculiarities of trematode distribution were typical for populations of both snail hosts. In general, results of our study suggest weak (if any) interference between populations of different trematodes in the community. This is probably due to the species composition of parasites and the ratio of infection prevalence by different trematodes.
|Состояние||Опубликовано - 1 янв 1995|
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