Effects of the eyefluke, Diplostomum spathaceum, on the behaviour of dace (Leuciscus leuciscus)


The behaviour of dace infected with Diplostomum spathaceum was investigated in the laboratory. As the number of parasites present in the eye increased, the efficiency with which the fish fed on Gammarus pulex declined. The loss of efficiency was compensated for by an increase in the time devoted to feeding. Heavily infected fish spent more time in the surface layers of the water. This may increase the likelihood that a gull might eat the fish and thereby continue the life-cycle of the parasite. The parasite modifies the behaviour of its host in a way that increases the parasite's chances of survival at the expense of the host. © 1980.