The effect of temperature on cercariae production of two Rhipidocotyle trematodes parasitizing freshwater mussel, Anodonta anatina.

Abstract

Two bucephalid trematodes, Rhipidocotyle campanula and R. fennica are known to infect the duck mussel, Anodonta anatina. The infection will lead to decrease growth, reproduction and survival of A. anatina. Given the important role of temperature on cercariae production, a vital component of the parasite’s transmission and life cycle success, the effect of temperature on cercariae production of two Rhipidocotyle sp. in their molluscan host, Anodonta anatina, was investigated. Mussels were collected from the Rivers, Haajaistenjoki and Kuusaankoski, marked and allocated to three temperature treatments—high, intermediate and low. Between May 31-October 28, 2011, clams were individually monitored every third week for cercarial emergence in the laboratory. Cercariae production was temperature-dependent but differential. R. campanula emergence started in late May and R. fennica in July. In the River Haajaistenjoki, in high temperature, average annual R. fennica production was higher (17000 larvae per mussel) than R. campanula (3000 larvae per mussel), but the opposite in low temperature (600 vs. 1300 larvae). Similar results were found from the River Kuusaankoski. Results suggest that R. campanula would be better adapted to low temperatures while R. fennica should have an advantage in high temperature habitats.