Zooplankton Epibionts in Boreal Lakes: Associations With <scp>DOC</scp> and Host Community Traits

ABSTRACT Epibiosis in aquatic ecosystems is well‐documented, yet the factors influencing epibiont prevalence and host selection remain unclear. This study investigates how water quality parameters and zooplankton community dynamics influence epibiont prevalence, with a focus on ecological implications. Field surveys across 12 lakes with varying water quality involved collecting crustacean zooplankton samples to assess ciliate epibiont prevalence. Correlations between epibiont prevalence, water quality, host density and body size were examined, while host specificity was evaluated using electivity indices. Results showed significant variation in water quality across the lakes, with dissolved organic carbon and total phosphorus positively correlating with epibiont prevalence. Host density was positively associated with prevalence, while high host density and species richness were associated with reduced epibiont load and prevalence. Strong host specificity was observed, suggesting selective pressures shaping zooplankton community composition. These findings highlight the complex interplay between water quality and biological interactions in aquatic ecosystems. The relationships between environmental factors, host density and host‐specific traits emphasise the importance of considering both abiotic and biotic factors in understanding epibiont dynamics. We provide empirical support for the ‘dilution effect’ hypothesis in the context of epibionts, highlighting the complex dynamics of host‐specific interactions. This study advances knowledge of freshwater ecosystem ecology and underscores the need for further research into the mechanisms driving epibiont–host interactions, particularly the roles of predation and resource availability.