The effects of Kureha’s PGA (polyglycolic acid) resin on the settlement of the marine sessile organisms (actinulae of the hydroid, barnacle cyprids and epiphytic diatoms) were examined in the laboratory. For this settlement assay, larvae or diatoms were placed on PGA resin plates in the polystyrene test vessels containing filtered sea water, and their behaviors was observed through various microscopes. The results showed that the PGA resin plates clearly inhibited larval attachment, and diatoms’ settlement and surface-gliding behavior without causing toxic effects. The settlement-inhibitory effects of PGA were counterbalanced by higher Ca2+ conditions. Lower Ca2+ environments and the microstructural changes with hydrolytic degradation in near-surface regions of the substrata may play important roles in settlement-inhibitory effects of PGA resin.
