Biofouling can be defined as a combination of physical, chemical and biological processes that lead to accumulation of organisms on artificial structures immersed in a water body. Current remedy for biofouling is antifouling paints having organo tin compounds as their active ingredients. Environmental concerns about the toxins in antifouling paint formulations has triggered extensive research though out the world to find a natural source that will not cause any threat to marine environment while serving as an effective antifoulant. Natural compounds obtained from sessile marine invertebrates which maintain clean surface even when there is abundant fouling in their vicinity, can be used as replacement for TBT. Presence of antifouling compounds have been reported from many marine sessile organisms like sponges, soft corals, bryozoans, ascidians, sea weeds and sea grasses.
Octocorals being sessile organisms are susceptible to colonization by various micro and macro foulers, hence the need to possess defenses against these organisms. Octocorals are known to possess an array of secondary metabolites having various biological activities. There are a number of reports indicating the presence of chemicals in soft corals which can prevent attachment of fouling organisms. Studies on secondary metabolites from octocorals have shown biological activity against bacteria and fungi. They are also shown to have antipredatory activity. There are a number of reports indicating the presence of chemicals in soft corals which can prevent fouling organisms from colonizing their surfaces. Octocorals from Indian waters are known to produce secondary metabolites with a wide range of biological activity. Diversity of corals in Indian waters is found to be very high and most of these corals maintain a clean surface.
Nations worldwide are imposing greater restrictions on the use of toxic materials in antifouling paints. But the ships need to be protected against biofouling. Research is going on through out the world to find a remedy for fouling. Most of the research is targeting marine organisms as a potential source for discovering antifouling compounds. If discovered these compounds will prevent fouling without causing any damage to the ecology of marine environment as these compounds have evolved within the same environment.