Seasonal differences in infestation of the perch Perca fluviatilis L. from Lake Constance with digenean trematodes.

ABSTRACT

Perch (Perca fluviatilis L.) caught in Lake Constance every 2 months over a period of 3 years below six towns or villages (Langenargen, Nonnenhorn, Rorschach, Romanshorn, Bottighofen, and the Lake of Uberlingen) were examined for parasites. In contrast to Diplostomum spathaceum (Rudolphi, 1819) and Tylodelphys clavata (Nordmann, 1832), Bunodera luciopercae (Müller, 1776) and Ichthyocotylurus variegatus (Creplin, 1825) showed marked seasonal differences. These differences were influenced by various factors the different numbers of the first intermediate hosts (snails, copepods), the water temperature, the physiological state of the fish, and its way of life.