Effects of the digenean parasites Labratrema minimus and Cryptocotyle concavum on the growth parameters of Pomatoschistus microps and P-minutus from Southwest Wales

During the present study, about 800 specimens of gobies (Pomatoschistus microps and P. minutus) from two sites at Gower Peninsula, Southwest Wales, were studied. Both species were infected with the digenean parasites Labratrema minimus and Cryptocotyle concavum. The effects of these parasites on host-growth parameters such as the condition factor, the gutted condition factor, the hepatosomatic index, and the gonadosomatic index were considered. The results of multiple regression and hierarchical analysis of variance (ANOVA) show that in P. microps, increasing numbers of C. concavum in the peritoneum appear to reduce the hepatosomatic index, whereas rising numbers of L. minimus increase it. In P. minutus, increasing numbers of L. minimus in the liver and muscle decrease the hepatosomatic index and the gonadosomatic index. The opposite effects of L. minimus on the hepatosomatic index of these host species are discussed.