Antifouling activities of marine sedentary invertebrates on some macrofoulers

Antifouling activities of alcohol extracts from four gorgonian species (Melitodes sp., Gorgonella sanguinolenta. Echinogorgia complexa, Acanthogorgia turgida), five soft corals [Dendronephthya sp. 1, Dendronephthya sp. 2, Dendronephthya (Roxasia) sp., Dendronephthya (Morchellana) sp., Dendronephthya (Spongodes) sp], three unidentified antipatharian species (coded as antipatharian sp.1, antipatharian sp.2, antipatharian sp.3) and five sponges [Plakortis simplex, Axinella sp., Fasciospongia cavernosa, Azorica pfeifferae, Dercitopsis sp.] against cyprids of the barnacle Balanus amphitrite and green mussel Perna viridis are reported here, All the extracts examined inhibited the settlement of cyprids of B. amphitrite. The EC 50 values of the extracts ranged from 16 ± 3 μg/ml (antipatharian sp.2) to 150 ± 8 μg/ml (antipatharian sp. 3). The LC 50 values of the extracts varied from 38 ± 3.8 μg/ml [Dendronephthya (Roxasia) sp.] to 218 ± 30.6 μg/ml (Fasciospongia cavernosa). A comparison of the EC 50 and LC 50 values reveal that most of the extracts are non toxic to the cyprids of B. amphitrite. In the case of P. viridis only 7 out of 17 extracts (41%) inhibited byssal production and attachment. Gorgonian coral extracts displayed highest incidence of attachment inhibitory activity (75%) followed by soft corals (40%), antipatharians (33%) and sponges (20%), when tested against P. viridis. The EC 50 values of the extracts ranged from 164 ± 12μg/ml (A. pfeifferae) to 898 ± 11μg/ml [Dendronephthya (Morchellana) sp.]. Toxicity revival studies indicate that the transient presence of active extracts did not cause irreversible damage to P. viridis. The results indicate the possible potentialities of these extracts as natural non toxic antifouling agents.