An offshore buoy as a small artificial island and a fish-aggregating device (FAD) in the Mediterranean

The ODAS Italia 1 oceanographic buoy is moored in the Ligurian Sea, 37 nm f rom Genoa, along the Genoa-Cape Corse transect (43 degrees 38.90' N-09 degr ees 06.80' E), over a 1270 m deep sea bottom. The underwater portion of the buoy is 37 m long and 0.60 m in diameter, acting as a small island for col onization of fouling organisms and as a fish-aggregating device (FAD), The role of the buoy in attracting and maintaining fish assemblages was investi gated by visual censuses in different seasons at depths of 0-40 m. Fish fro m seven families, comprising 12 species, of which three an benthic, were re corded with maximum abundance in summer. Fouling was studied from samples c ollected on the buoy and on immersed panels. The fouling community of the b uoy consisted of 34 algae and 100 animal species, including three fish. The settlement processes of the fouling community on the panels, in particular on those exposed for over 70 months at 12 m and 33 m depth, are described based on counts of settled organisms, the covering index of each taxa and b iomass assessments. On the panels, 63 species were identified. The fouling biomass, on the panel submerged for 70 months, assessed as wet weight. reac hed 2.8 kg/m(2) at 12 m depth and 4.8 kg/m(2) at 33 m depth. Observations of benthic organisms settled directly on the buoy were made be tween 1988 and 1989 and when the buoy was retrieved and brought back to sho re on April 15, 1991 after 52 months at sea. At this time, the fouling comm unity along the full 37 m length of the buoy was sampled. and 91 taxa, incl uding 83 species, were identified. Several of the: species present on the b uoy are shallow, coastal species. some with a very short larval period. Pos sible ways of colonization by such species are discussed. Despite seasonal changes, the pelagic fish community was more stable over the period of 11 y ears of study than the benthic community settled on the buoy (that is still developing).