Effect of host weight on the distribution of Argulus foliaceus [L.] [Crustacea, Branchiura] within a fish community

Spatial heterogeneity is a feature common to many ecosystems. Aquatic organisms typically exhibit this heterogeneous distribution but to date little is known about the distribution of many common parasite species within water bodies. In this study the distribution of Argulus foliaceus (L.), an ectoparasitic crustacean, on different sized hosts within a mixed species fish community was determined. Different fish species exhibited differences in their louse burdens (prevalence and intensity). The highest prevalence of A. foliaceus was observed on fish species dominated by larger individuals (i.e. Cyprinus carpio, Abramis brama and Tinca tinca). C. carpio and A. brama also exhibited the highest mean louse intensities. Infested fish were generally heavier than uninfested conspecifics. Differences in the weight of uninfested and infested fish were significant (P<0.05) for the whole fish community samples and the Scardinius erythrophthalmus, A. brama and C. carpio samples. There was also a general pattern of increasing infestation intensity with an increase in host body weight, with significant correlations for the whole fish community for S. erythrophthalmus, A. brama and C. carpio samples. In addition there were significant differences in parasite prevalence and intensity between different host weight groups and larger (heavier) fish appeared to be more prone to infestation by A. foliaceus.