The Effect of Substrate Conditioning on Larval Settlement and Spat Growth of the Cupped Oyster, Crassostrea belcheri (Sowerby), in a Hatchery

Abstract

Substrate conditioning is a key factor for the settlement and metamorphosis of oyster larvae. The effects of substrate conditioning on larval settlement and growth of spat of the cupped oyster, Crassostrea belcheri, were evaluated in three trials in a closed recirculation system. Particles prepared by grinding clean oyster shell were used as a substrate for larval settlement. In each trial, substrates were conditioned by immersion in seawater for 2, 12 and 24 h before use. The number of larvae that settled on substrates conditioned for 2 h was significantly higher (P < 0.05) than the number that settled on substrates conditioned for 12 and 24 h in all trials. Mean setting rates ranged from 30.44 ± 9.71 to 61.71 ± 11.28, 7.61 ± 3.51 to 35.77 ± 1.67 and 6.21 ± 1.38 to 32.77 ± 1.57 on substrates conditioned for 2, 12 and 24 h, respectively. Differences in the increments of shell width and length among oyster spat nursed over 3 wk on substrate conditions for different lengths of time were nonsignificant (P > 0.05).