MEPS 192:195-202 (2000)  -  doi:10.3354/meps192195

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

Yuji Tomaru1,*, Zen'ichiro Kawabata2, Shin-ichi Nakano3

1Department of Environmental Conservation Sciences, The United Graduate School of Agricultural Sciences, Ehime University, Tarumi 3-5-7, Matsuyama 790-8566, Ehime, Japan
2Center for Ecological Research, Kyoto University, Otsuka 509-3, Kamitanakami-Hirano-cho, Otsu 520-2113, Shiga, Japan
3Department of Environmental Conservation, Faculty of Agriculture, Ehime University, Tarumi 3-5-7, Matsuyama 790-8566, Ehime, Japan

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.

KEY WORDS: Pearl oyster larvae · Clearance rate · Picoplankton

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