Na2-EDTA Effects on the Development of Oyster, Crassostrea belcheri (Sowerby) Larvae

Abstract

The effect of different concentrations of a disodium salt of ethylenediamine tetraacetic acid (Na₂-EDTA) on the development of oyster Crassostrea belcheri, was studied and the highest percentage of fertilized eggs that developed into normal trochophore larvae was found to occur in seawater untreated with Na₂-EDTA. However, no signifi cant differences in mean percentages of embryos that developed into normal D-larvae were found among untreated and treated units at Na₂-EDTA concentrations ranging from 5 to 20 ppm (P > 0.05). In the study on the effect of conditioning periods of Na₂-EDTA pre-treated seawater on the development of oyster larvae, non-signifi cant differences were found among the mean percentages of fertilized eggs that developed into normal trochophore larvae in untreated seawater and seawater pre-treated with Na₂-EDTA and conditioned from 0 to 48 hr (P > 0.05). However, mean percentages of embryos that developed into normal D-larvae was highly signifi cantly different among treatments (P < 0.01), with the highest percentage occurring in untreated Na₂-EDTA seawater.