GROWTH, SURVIVAL, AND FEEDING RATES FOR THE GEODUCK PANOPEA GLOBOSA DURING LARVAL DEVELOPMENT

ABSTRACT Developmental larval stages of the geoduck Panopea globosa (Dall, 1898) are described for the first time. Growth rate, survival, and the length—size relationship were also assessed at 22°C in five independently reared cohorts. Clearance rates (CR), ingestion rates (IR), dry weight, and organic weight of select larval stages were quantified in two additional runs. Clearance rates and IR were evaluated as a function of cell concentration (50, 100, 200 and 300 cells/µL) of the chrysophyte Isochrysis sp. (clone T-ISO) using static systems. Conspicuous larval stages appeared after 20 h (trochophore), 24 h (straight hinge or “D”), 5–6 day (early umboned), 9–10 days (intermediate umboned), 11–12 days (late umboned), and 12–14 days (pediveliger). The larval period for P. globosa lasted between 12 days and 14 days, and the shell length recorded at settlement ranged from 332–356 µm (mean, 343 ± 4.2 µm). The overall average gross growth rate of the five larval cohorts was ∼20 µm/day. The relationship betwee...