Variation in clearance and ingestion rates by larvae of the black-lip pearl oyster (Pinctada margaritifera, L.) feeding on various microalgae

Clearance rate (CR) and ingestion rate (IR) of different sizes (89, 125 and 188 lm shell length) of Pinctada margaritifera larvae were determined when feeding on various microalgae. The microalgae tested were the diatoms, Chaetoceros muelleri and C. simplex, and flagellates, Tahitian Isochrysis aff. galbana, Pavlova lutheri and P. salina at 5 or 10 cells lL. Both CR and IR of microalgae tested in this study increased with increasing larval size; but at all larval sizes, diatoms resulted in lower CR and IR. Of the microalgae tested, P. margaritifera larvae showed greatest CR and IR with the two Pavlova spp. Maximum CR for P. salina was 10.5, 21.2 and 29.7 lL h for larvae with shell lengths of 89, 125 and 188 lm, respectively. The highest IR values for P. margaritifera larvae with shell lengths of 89, 125 and 188 lm were 8.7, 81.0 and 165.7 cellsÆlarva h, respectively. CR and IR of P. salina were approximately five times higher than those recorded for C. muelleri and C. simplex.