These data were published in Truskey et al. 2025 (Evolutionary Applications).
In fall 2018, we haphazardly collected live oysters from each reef by scuba or snorkel. We repeated sampling in fall 2020, when lower live oyster densities resulted in variable sample sizes among reefs. Following collection, oysters were placed on ice, transported to the Northeastern University Marine Science Center, and stored at −80°C until subsequent processing and analysis.
Measuring oyster traits
To assess variation in oyster traits associated with genetic cluster identity, we recorded the following size-related measurements for all oysters sampled in fall 2018 and 2020: shell height (mm) from the hinge to the outer shell edge; shell length (mm) from one lateral shell edge to the other at the widest point perpendicular to height; dry tissue and shell mass (g; tissue and shells dehydrated in drying oven for ≥ 48 h). We calculated oyster condition index as dry tissue mass × 100 divided by dry shell mass (i.e., dry tissue weight: dry shell weight ratio; Lucas and Beninger 1985; Mann 1978).
Additionally, for oysters sampled in fall 2018, we assessed infection by four common oyster parasites: the microparasites Perkinsus marinus (urn:lsid:marinespecies.org:taxname:562957) and Haplosporidium costale (urn:lsid:marinespecies.org:taxname:394948), the causative pathogens of Dermo disease and SSO disease, respectively, and the macroparasites, Cliona spp. boring sponges and Polydora sp. mud blister worms. To assess infection by the microparasites, we used DNA extracted from the 32 oysters sampled per reef in 2018 and performed a polymerase chain reaction (PCR) assay protocol developed for SSO (Stokes and Burreson 2001) and a quantitative polymerase chain reaction (qPCR) assay for Dermo (De Faveri et al. 2009). For macroparasite presence, we surveyed the shells of individual oysters for physical signatures of macroparasites (i.e., holes characteristic of boring sponge; interior blisters indicating burrowing by mud blister worms). In addition to infection presence, we also report infection intensities (parasite load or concentration, per infected host) for the two most prevalent oyster parasites (P. marinus and mud blister worm) as an additional axis of potential variation in the response (tolerance) of oysters to parasites. Standardized intensity values for P. marinus were generated through the above cited qPCR protocol. For mud blister worm intensity, we quantified the overall proportion of parasite-affected shell area using ImageJ (Abràmoff et al. 2004) following protocols from Hanley et al. (2023).
