Body size, season, and host taxon predict patterns of monogenean gill parasite infection in two assemblages of darters (Percidae: Etheostomatini) in Tennessee

Parasites are an important component of freshwater ecosystems due to the ways they regulate energy flow and shape community structure. The goal of this study was to analyze infection patterns of monogenean gill parasites (genus Aethycteron) that have specialized on darters (genus Etheostoma), freshwater fishes native to North America. We sampled hosts from two stream sites in Tennessee and evaluated whether prevalence and intensity of infection varied in the hosts by site, season, body size, sex, or host taxon. Month, standard length, and host clade were strong predictors of infection patterns. Darters of the clades Stigmacerca and Catonotus were heavily infected, while clade Neoetheostoma presented with moderate parasite burdens, and clades Adonia, Boleichthys, and Ulocentra presented with low parasite burdens. Prevalence and intensity significantly varied by month, with infections tending to peak during warmer months in most species. Host sex and site were not significant predictors of prevalence or intensity of infection, although intensity was higher at one site than at the other. Our results provide key insights into a vastly under-studied group of specialist parasites. Furthermore, our study contributes to the growing knowledge base of the pathogen pressures faced in nature by an important and diverse group of North American biological indicator species.