Abstract
The clearance rates (CRs) of the Manila clam, Ruditapes philippinarum Adams et Reeve, were measured for chlorophyll- a (Chl- a) and various potential prey items (bacteria/picocyanobacteria to chain-forming diatoms) at 24 °C in the laboratory. The clams filtered particles actively in 12 out of 16 experimental runs. In these runs, the soft-body-dry-weight (DW)-specific clearance rates (CR*s) for Chl- a were greater than 1.5 dm 3 g DW −1 h −1 (average=2.3 dm 3 g DW −1 h −1) and comparable to those reported by other groups. Picocyanobacteria (∼1-μm long) and prey items larger than 2 μm were also filtered effectively. However, free-living bacteria (∼0.4-μm long) were filtered in only six runs and the CRs for bacteria were much lower than for other prey items. The ratios of the CR* for each prey item to that for Nitzschia spp. (70–80-μm long) were close to unity for prey longer than 2 μm, which indicates that particles ≥2 μm are filtered with similar efficiency by the clam. For picocyanobacteria and free-living bacteria, these ratios were 0.70 and 0.11, respectively.
Published Version
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