2.2.2. Experiment 3: feeding and ingestion
To ensure similar rearing densities in each tank, ten small, five medium and two large gut-evacuated sea cucumbers were stocked separately in three tanks (45 cm × 35 cm × 30 cm) with six replicates. The sea cucumbers were fed to satiation twice per day at 08:00 and 20:00 for 4 days. The remaining uneaten feed and feces were siphoned before exchanging water twice per day, followed by gentle rinsing with freshwater to remove salt. The uneaten food and feces were dried separately at 60 °C to constant weight. Both ingestion rate (IR) and feces production rate (FPR) were calculated as described by Maxwell et al. [22]:
IR (mg g−1 h−1) = ((Wo − Wu) / Wsc) / t
FPR (mg g−1 h−1) = (Wf / Wsc) / t
where Wo = dried weight of the offered food (mg); Wu = dried weight of the uneaten feed (mg); Wsc = wet weight of the sea cucumber in the tank (g); Wf = dried weight of the feces (mg) and t = time (h).