Novel non-toxic coating technology for biofouling control developed for the aquaculture industry is presented that relies on the photoactive generation of hydrogen peroxide to reduce the settlement of biofouling organisms rather than the leaching of pesticides .
Biofouling, the unwanted growth of biological organisms on underwater surfaces, has long been recognized as a major problem for commercial aquaculture. Bio fouling dramatically increases labor costs, reduces the value of product, and can harm cultured species. Fouling clogs gear, stops water flow and food delivery, can compete with culture organisms for food or space, and can directly affect the growth and survival of cultured organisms. As a result, considerable physical and economic effort is directed toward the prevention and control of biofouling at culture facilities. Cleaning of gear and use of toxic coatings are the primary methods employed by the industry to maintain biofouling-free surfaces. Time and energy expended to keep gear clean taxes aquaculturalists consuming as much as 30% of labor costs and contributing 15% to operational costs.
A novel bio- based release coating was developed that, when immersed in water, controls the settlement of biofouling organisms. Biofouling control is accomplished by the release properties of the polymer that degrades and dissolves when exposed to sunlight. Catalysts in the formula generate low levels of hydrogen peroxide when exposed to sunlight. Peroxides are oxidizing agents known to thwart the settle ment of biofouling organisms. Peroxides also facilitate the gradual breakdown of the bio-based coating resulting in a release of the surface layer, and along with it any biofouling that may have attached. This solution to the biofouling problem is sustainable because p eroxides quickly dissociate back to oxygen and water after leaving the coating surface, and all ingredients in the bio-based coating are generally regarded as safe (GRAS) .
Results from b iofouling resistance testing on PVC test panels and aquaculture gear (bags, trays and cages) performed from 2015 to 2018 are presented. Oysters and scallops grew significantly larger in treated bags and trays over a three month grow-out period. Treated gear requires less maintenance and can be reused without cleaning. Results from field testing demonstrate that photoactive release coating technology is a viable solution to the biofouling problem experienced by shellfish farmers, who rely on gear changes and cleaning to control biofouling.
Key words: Photoactive, Release coating, Biofouling, Non-toxic, Bio-based