| Abstract: | The mortality of prosobranch snails Hydrobia ulvae uninfected and infected with the parthenites of two species of Trematodes (Bunocotyle progenetica and Cryptocotyle cancavum) after freezing in seawater of different salinity with following thawing has been studied. Reduced salinity exceeds mortality of snails under freezing significant (p < 0.01). The mortality of mollusks increases significant (p < 0.01) with the increase of the exposure time. The mortality of females exceeds the mortality of male significant (p < 0.01) within the group of 2-years individuals. The negative effect of trematode invasion to the vitality of mollusks after freezing was not showed. Trematode infestation registered in March 2004 and in September 2003 is not significant differ (Levakin, 2004). Thus any important differential mortality of individuals H. ulvae infected with parthenites of this Trematodes is not present during a winter time. The conclusion is conformed by the results of our experiments and well accords to features of realization of life cycles of these Trematodes under conditions of the White Sea intertidial zone, where infection is possible only within the worm season. |
