Infestation patterns of microphallid trematodes in Corophium volutator (Amphipoda)

Infestation patterns of digenetic trematodes in Corophium volutator (Pallas , 1766) were studied in a shallow-water area of the: southern Baltic Sea. T he amphipod C. volutator is the most common second intermediate host of mic rophallid trematodes, in particular Maritrema subdolum, in this area. Seaso nal and interannual alterations in infestation among the amphipod populatio n are described. The general trend of infestation followed a relatively inv ariable seasonal pattern. Lowest prevalences were generally observed in spr ing and early summer, when juvenile amphipods predominated. increasing prev alences and relative infestation intensities were recorded over the summer, with the highest values in late summer and autumn. These observations are mainly explained by the population dynamics of C. volutator and the infecti on dynamics of the first intermediate hosts, mudsnails of the genus Hydrobi a. Exceptionally high infestation rates in summer 1997 may have been trigge red by the earlier appearance of high col caria densities in the held compa red to 1996. The coincidence of the infection dynamics of the first interme diate host With the population dynamics of C. volutator was apparently impo rtant. Parasite infestation, in turn, obviously induced mortality of the cr ustacean host, but conclusive evidence could not be provided based on the a nalysis of the parasite dispersion patterns in C. volutator. (C) 2001 Elsev ier Science B.V. All rights reserved.