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 pm) ranged between 0.08 and 0.12 p1 larva-' h-', and those of APP between 0.12 and 1.5 p1 larva-' h-' Grazing pressure on natural populations of bacteria and APP by the larvae was estimated as < O.O1'bk d-' in Uchiumi Bay, suggesting that these larvae play a minor role in the consumption of p~coplankton.

Application of a bioenergetic growth model to larvae of the pearl oyster Pinctada margaritifera L.

“…Also, we used chlorophyll a (Chl a) as a des criptor of food resources although the Chl a composition of phytoplanktonic cells can vary between species and with environmental conditions, as can the ratio of carbon/Chl a, which is an indicator of the energy content of cells (Pridmore and Hewitt 1984;Cloern et al, 1995). Larvae are also susceptible to exploit resources other than autotrophic plankton, such as bacteria (Tomaru et al, 2000), heterotrophic plankton and dissolved matter (Olson and Olson 1989;Baldwin and Newell 1995). Nevertheless, the model seems capable of reproducing growth correctly with Chl a forcing, notably in variable conditions such as those observed in the in situ trials.…”

Relative importance of nanoflagellates and ciliates as consumers of bacteria in a coastal sea area dominated by oligotrichous Strombidium and Strobilidium

“…Pearl oysters Pinctada fucata are cultivated in this area, the production level of which is the highest in Japan. Oyster larvae graze on bacteria and picocyanobacteria (Tomaru et al 2000) and, hence, studies on the ecology of the microbial food web in this area are important not only to assess food web structure and function, but also to assess fisheries management. The bay is oligo-to mesotrophic, based on its chlorophyll levels, which are usually < 2 µg l -1 (Tomaru et al 2002).…”

Bacteria as food in aquaculture: do they make a difference?

“…With natural assemblages of bacteria, clearance rates by larvae of the Japanese pearl oyster Pinctada fucata martensii were low, ranging between 0.08 and 0.12 μL larva −1 h −1 , corresponding with an average of 347 bacteria larva −1 h −1 (Tomaru et al . ). The assimilation yield of the bacteria varied between 22 and 33% in P. maximus larvae (Moal et al .…”

“…Ingestion efficiency is reported to be 10-15% of the value for algae in C. gigas and P. maximus, reaching values up to 27 000 bacteria larva À1 h À1 in C. gigas (Douillet 1993b;Moal et al 1996). With natural assemblages of bacteria, clearance rates by larvae of the Japanese pearl oyster Pinctada fucata martensii were low, ranging between 0.08 and 0.12 lL larva À1 h À1 , corresponding with an average of 347 bacteria larva À1 h À1 (Tomaru et al 2000). The assimilation yield of the bacteria varied between 22 and 33% in P. maximus larvae .…”