The peculiarities of the helminth fauna of herring gulls of the synanthropic Murmansk population

Abstract

The feeding resources of seabirds have been con� siderably damaged in the Barents Sea region in the second half of the 20th century, which mainly resulted from largescale commercial fishery. A pronounced tendency towards synanthropy of some seabird spe� cies, mainly the herring gull (Larus argentatus), is one of the most important and obvious consequences of this process. Herring gulls especially intensely spread to anthropogenic landscapes of the Kola Peninsula in the late 1970s and early 1980s, when the birds began to use food waste cans, municipal garbage dumps, and wastes from fur farms as feeding stations (1-3). Until the late 1990s, gulls only scavenged for food in urban areas; then, they began nesting and raising their nest� lings on the roofs of town buildings, including those within the city limits of Murmansk (4). The reproduc� tion efficiency was very high there, as evidenced by large sizes of the clutches and a low mortality of the nestlings (4, 5). Such considerable changes in the bird ecology and behavior could not but affect the compo� sition of their helminth fauna. However, there have been few, if any, reliable data on the parasites of the seabirds that have moved from their traditional habi� tats to urban landscapes. Parasitological examination of herring gulls from the synanthropic Murmansk population was carried out in the Laboratory of Ornithology and Parasitology of the Murmansk Marine Biological Institute of the Kola Scientific Center of the Russian Academy of Sci� ences in 2009-2010. The purpose of this study were to determine the species composition of the helminthic fauna of the gulls, compare the results with the data on the helminth infestation of birds from natural popula� tions of the Murmansk coast, and evaluate the anthro� pogenic effect on the pattern of helminth invasion in herring gulls. We used the material from 13 birds that were found dead (usually, after collisions with motor vehicles) on the streets of Murmansk. Helminthes obtained from the intestine and other organs of the birds were fixed using the standard method (trematodes and cestodes, in 70% ethanol; nematodes, in a warm 4% formalin solution in seawater). We made whole mounts out of the fixed trematodes and cestodes stained by mucicar� mine; these specimens were used for species identifi� cation of the parasites. To identify the species of nem� atodes, we preliminarily clarified the specimens with 10% glycerol. Quantitative parameters of the infesta� tion of gulls by different species of parasites, namely the prevalence and intensity of invasion (P and II, respectively) and the mean abundance (MA), were determined from the result of parasitological dissec� tions. For comparative analysis, we used the data on the parasitic fauna of herring gulls from the Seven Islands Archipelago obtained in 1993-2001 (6). The statistical treatment of the results included the estima� tion of the boundaries of the confidence intervals for P at the 5% significance level and the calculation of Jac� quard's and Sorensen's coefficients.