LARVAL TREMATODE INFECTIONS IN FRESH-WATER GASTROPODS FROM THE ALBUFERA NATURAL PARK IN SPAIN

Malacological samplings were made from January 1994 to December 1996 i n the Albufera Natural Park (Valencia, Spain) to trace the dynamics of molluscan populations and the prevalence and intensity of infection b y larval trematodes. A total of 10,533 freshwater gastropods belonging to seven species (Lymnaea auricularia, L. truncatula, L. palustris, L . peregra, Bithynia tentaculata, Physa acuta and Gyraulus chinensis) w as examined, and 110 (1.04%) were found to harbour some of the nine di stinguishable types of cercariae, namely four echinostome cercariae (H ypoderaeum conoideum, Echinoparyphium recurvatum, Euparyphium albufere nsis, and Echinostoma sp.), four furcocercous cercariae, and one xiphi diocercous cercaria. This study shows that the composition of the snai l and trematode communities may be determined by the particular enviro nmental conditions present and the human intervention in the area.