Consumption of picoplankton by the bivalve larvae of Japanese pearl oyster Pinctada fucata martensii

Abstract

We examined grazing on bacteria and algal picoplankton (APP) by the larvae of Pinctada fucata martensii, using fluorescently labeled bacteria (FLB) and algae (FLA). Ingestion of both FLB and FLA by the larvae indicated that bacteria and APP serve as food sources for the larvae. With natural assemblages of bacteria and APP, the clearance rates of bacteria by the larvae (70 to 200 μm) ranged between 0.08 and 0.12 μl larva-1 h-1, and those of APP between 0.12 and 1.5 μl larva-1 h-1. Grazing pressure on natural populations of bacteria and APP by the larvae was estimated as < 0.01% d-1 in Uchiumi Bay, suggesting that these larvae play a minor role in the consumption of picoplankton.