Helminth Fauna of Auks (Charadriiformes, Alcidae) in the Barents Sea: Composition, Structure, and Ways of Formation

Based both on original and published data, the results of long-term studies on the helminth fauna of alcids (the little auk, Alle alle; the razorbill, Alca torda; the Atlantic puffin, Fratercula arctica; the black guillemot, Cepphus grylle; the common guillemot, Uria aalge; and Brünnich’s guillemot, U. lomvia) in the Barents Sea region are summarized. In total, 31 species of helminths (four trematodes, eleven cestodes, 12 nematodes, and four acanthocephalans) have been revealed. Some of them circulate in coastal ecosystems, but the implementation of life cycles in most species occurs in the pelagial zone with the participation of planktonic invertebrates and fish as intermediate and transport hosts. Of the total number, 24 species of helminths do not reach maturity in alcids and use either other birds or marine mammals as obligate definitive hosts. The structure of the parasitic fauna and the peculiarities of the geographic and interspecific distribution of helminths are related to the evolutionary age of parasite–host systems, host ecology, and parasite specificity. A comparative analysis of the helminth faunal composition of alcids in the North Atlantic and Barents Sea shows that Barents Sea birds have a lower diversity of trematodes and cestodes. Differences in the nematode faunal composition are insignificant, whereas records of acanthocephalans are more frequent in the Barents Sea. This seems to be accounted for by different species of parasites having different requirements for environmental conditions and varying degrees of specificity to both intermediate and definitive hosts.