Prevalence and intensity of oyster parasite species following a reef restoration experiment in Quonochontaug Pond, Rhode Island, USA from 2017-2020

Intraspecific variation in host susceptibility to individual parasite species is common, yet how these effects scale to mediate the structure of diverse parasite communities in nature is not as well understood. To address this knowledge gap, we tested how host genetic identity affects parasite communities on restored reefs seeded with juvenile oysters from different sources – a regional commercial hatchery or one of two wild progenitor lines. We assessed the prevalence and intensity of three micro- and two macro-parasite species for four years following restoration. Despite the spatial proximity of restored reefs, oyster source identity strongly predicted parasite community prevalence across all years, with sources varying in their relative susceptibility to different parasites. Oyster seed source also predicted reef-level parasite intensities across space and through time. Our results highlight that host intraspecific variation can shape parasite community structure in natural systems, and reinforce the importance of considering source identity and diversity in restoration design.