MARINE SPONGE EXTRACT AS A PROMISING SOURCE OF NATURAL ANTIFOULANTS

STUPAK, M.; GARCIA, M.; BLUSTEIN, G.; PALERMO, J.A.; SÁNCHEZ, M.; PÉREZ, M.

Río de Janeiro

Congreso; Congresso Brasileiro de Oceanografia; 2012

Associação Brasileira de Oceanografia

Marine biofouling is the attachment and growth of living organisms on solid surfaces immersed in marine environments; it is a complex sequence of events influenced by several chemical, physical and biological processes. Fouling organisms attached to man-made surfaces submerged in marine waters constitute a major worldwide technical and economical problem, particularly to those industries involved in aquaculture, shipping and building and maintaining off-shore structures. Protection against biofouling is essential for efficient service of boats and ships. The most successful techniques have involved coating ship hulls with metal-containing antifouling paints. These paints are usually based on copper or tin compounds that protect against fouling by continuously releasing the toxic compound into the surrounding seawater. Due to recent and imminent restrictions of the use of traditional, toxic antifouling paints there is a growing need for searching new alternative compounds for marine antifouling paints. An ethanolic extract from a marine sponge with potential antifouling activity was included in soluble matrix paints. The sponge extract of Clathria microxa was selected due to the absence of fouling on the organism´s surface and the presence of complex secondary metabolites. For the preparation of the soluble matrix antifouling paint, colophony (resin) and oleic acid (plasticizer) were dissolved in a xylene/white spirit (1:1 % by weight) mixture using a high-speed disperser. Then, a laboratory scale ball mill was loaded with the vehicle followed by zinc oxide and calcium carbonate which were dispersed for 24 h. The extract (0.8% v/v) was incorporated to the paint and then, dispersed during 1 h. Sandblasted acrylic tiles (4 cm×12 cm) were used for field trials. Paints were applied by brush on tiles previously degreased with toluene. Three coats of paint were applied and allowed to dry for 24 h between each application, resulting in a final dry thickness of 150±5 µm. Panels were hung in a marina in Mar del Plata harbor (Argentina) to a depth of 50 cm below the water line. In addition, two controls were used, one of them was unpainted acrylic tiles and the second one, tiles treated with paint without extracts. After three month exposure in the sea, natural product-based paints were effective in inhibiting settlement. A great decrease in micro and macro-fouling density and diversity was observed in relation to controls (p