Minimum effective release rate of antifoulants.1. Effects of zosteric acid at Ford Island, Hawaii (USA).

Minimum effective release rate (MERR) of zosteric acid (ZA) was studied at Ford Island. At laboratory condition, spore attachment in Enteromorpha intestinalis was inhibited significantly at 28.2 microg cm2 of ZA. More than 95% reduction in spore attachment was achieved in Ulva fasciata at 2,000 microM of ZA through membrane diffusion system. At 40 cm depth level larval settlement was high with maximum number of Hydroides elegans settlement. The overall larval settlement was increased with increasing days of exposure. The MERR of 10 microg cm(-2) d(-1) ZA inhibited 50% of the larval settlement. However, the inhibition rate was not proportionate to the antifouling ZA concentration. Using MERR membrane diffusion system an effective antifouling strategy was suggested for Ford Island.

Antifouling activity of six nontoxic chemicals on spore attachment of Ulva fasciata.

Marine biofouling cause severe damage to all marine technologies. Indiscriminate use of toxic metallic antifouling (AF) chemicals (cuprous oxide and TBT) to control the biofouling in turn greatly affects the flora and fauna of the marine ecosystem. In search of environmentally safe and effective AF agents, six nontoxic AF candidates were studied against the spore attachment of Ulva fasciata. Spore attachment was inhibited at 100 microg of trans-cinnamic acid (TCA) and benzoic acid (BA). Sulfate-coumaric acid (SCA) had no significant effect on the spore attachment. The release rate of BA exhibited a constant release flow. Varied response of U. fasciata spores to AF chemicals and release rate to the surrounding medium are discussed.