Improvement of sea water quality by physical and chemical pre-treatment in a bivalve hatchery

The development to the veliger stage of fertilised ova of the Pacific oyster, Crassostrea gigas, was compared in raw natural sea water and in sea water pre-treated with various substances. Significantly higher veliger yields were obtained when the water was pre-treated with 1 mg l^?1 EDTA. Combinations of EDTA and 20 mg l^?1 sodium metasilicate, or 20 mg l^?1 alumina, or 50 mg l^?1 magnesium trisilicate or 150 mg l^?1 Fuller's earth also enhanced development.