Dataset: E. depressus metabolism

Eurypanopeus depressus were collected by hand from oyster reefs within the North Inlet Estuary (33°20’N, 79°10’W, Georgetown, South Carolina) 24 hours prior to experimentation. All oyster reefs were within 5 km of each other and no oyster reef was closer than 200 m to another sampled reef. Infected crabs were identified by the presence of parasite externae which signifies the parasite was mature. We only used infected crabs with a single mature externa to reduce any variation produced by multiple infections. Our sampling methods could not discern whether crabs were infected with the immature, internal phase of the parasite, so it is possible that some crabs categorized as “not infected” did have infections. We utilized male and female crabs in both infected and uninfected treatments because the effects of parasitic castration made distinguishing the sex of infected crabs difficult.  Crab carapace width were measured to the nearest 0.5 mm using a Vernier caliper while weight was measured to the nearest 0.01 g with a top loading balance AEP-2500G.

Crabs were starved 24 hours prior to experimentation to standardize hunger levels and were monitored for 24 hours after the experiment to ensure none underwent ecdysis or extruded eggs. We determined whether parasitic infection reduced the metabolic rate of E. depressus by measuring the oxygen consumption rate of infected and uninfected E. depressus inside hermetically sealed individual plastic containers (20 x 12 x 11 cm). Filtered seawater (salinity 32–34, temperature 24.3 ± 0.8 °C, 1 µm filter) was collected from North Inlet. Containers were set on a stirring plate and compartmentalized with plastic mesh in cylindrical form (diameter 12 cm, height 11 cm, pore size 0.5 cm).  A magnetic stirrer was placed in one compartment to ensure all dissolved oxygen (DO) was distributed evenly within the container. The other compartment received either a single infected crab, uninfected crab, or no crab (control) depending on the treatment. Each trial had two replicates of each treatment, with five trials run over three consecutive days (n = 10 for each treatment). Trials lasted one hour with a 10 minute acclimation period beforehand to help reduce the effect of handling. Concentration of DO and temperature was measured every 10 minutes using a microprocessor dissolved oxygen meter with a Clark-type electrode (Hanna Instruments, HI 9146N). DO was measured to the nearest 1 ppm while temperature was measured to the nearest 0.1 °C.