The occurrence ofCaryophyllaeus laticepsin the naseChondrostoma nasusfrom Austrian rivers: possible anthropogenic factors
AbstractBetween April 2003 and November 2006 a total of 198 naseChondrostoma nasus(L.) were examined for parasites from seven river sites in Austria. The selected sites showed different levels of anthropogenic alterations in river morphology ranging from pristine areas, with minor anthropogenic alterations, to strongly physically altered rivers. A variety of parasites were recovered from the skin, gills, swimbladder and eyes, withCaryophyllaeus laticeps(Pallas) being identified as the only cestode species occurring in the intestine. This is the first record of this species in nase in Austria.Caryophyllaeus laticepswas confined to the first 20% of the intestine, even in heavily infected hosts. The occurrence ofC. laticepswithin the fish population seems to be correlated with the degree of anthropogenic changes of the nase's habitat. In rivers with a high degree of ecological integrity or in rivers that are only partially dammed,C. laticepsis either absent inC. nasusor occurs with low prevalence (5.6–20%) and low mean intensity values (1.0–4.0). Where anthropogenic factors have changed the entire river into a reservoir, and fish cannot escape, the prevalence of infection withC. laticepsincreases from 46.2 to 78.2% and the mean intensity from 8.8 to 17.2.