Seabird helminth fauna and parasite life cycles on the Murman coast of the Barents Sea in winter.

Abstract

In winter, helminthes circulating throughout the coastal ecosystems of northern seas have to overcome significant difficulties in order to complete their life cycles. Unfavorable temperature conditions partly or completely suppress the activity and viability of the freeliving stage of parasi tes and trophic interactions between the intermediate and final hosts, since many fish species migrate into depths, the migratory birds and mammals are moving away, and many inverte� brates of the coastal complex are falling into winter anabiosis. The annual circulation of helminthes is therefore believed to be limited to a rather short time interval, the socalled "transmission window." Nevertheless, parasitological studies conducted on the Murman coast have revealed significant diversity of the helminth fauna in birds spending winter in this region, while the parameters of invasion by with some parasite species proved to be even higher than in summer periods. To identify the main adaptive mechanisms respon� sible for successful helminth circulation in winter on the Barents coast, the following three marine bird spe� cies wintering on Murman were used to study species composition of parasitic helminth fauna: the glaucous gull ( Larus hyperboreus Gunn., 8 specimens were examined in February-March 2006-2007 in the Kola Bay middle elbow); the common eider duck (Somate� ria mollissima L., 8 specimens were examined in Janu� ary-February 1994 and 1999 in vicinity of the Dal'nie Zelentsy settlement); and the purple sandpiper (Calid� ris maritima Brunn., 23 specimens were examined in February 1994 and 2011 in the Yarnyshnaya Bay). Bird autopsy, searching and fixation of helminthes, making the preparations, and identification of parasite species were performed using standart methods. The quantita� tive parameters, such as bird invasion, i.e., extensive� ness and intensity of invasion (EI and II, respectively), and abundance index (AI) were determined from the results of helminth identification and calculations. The pathways of helminth circulation in winter were also studied, as well as the biology and ecology of the intermediate and final hosts. In the course of this study, 44 helminth species were identified in the birds wintering in coastal Murman (18 trematode, 20 cestode, 3 nematode, and 3 acan� thocephalan species). The helminth fauna of the com� mon eider duck includes 16 parasitic worm species; those of the glaucous gull and purple sandpiper include 11 and 20 species, respectively. The composi� tion of the helminth fauna is shown in the table.