A study of the coastal fish assemblages in the marine park of Ustica Island (Southern Tyrrhenian Sea, Mediterranean) was conducted from June 1994 to September 1995 and from June 1996 to September 1997. The principal aims of the research were to: (1) define the faunistic features of local fish communities; (2) assess the effectiveness of the protection regime of the marine park on the fish assemblages (‘reserve effect’); (3) provide information on the distribution of some Epinephelus and Diplodusspecies in the shallowest depth zone of the island. During seasonal surveys, underwater visual censuses were carried out at several sites located in three zones of the island, each with a different level of protection. Observations were made along 250 m2 transects at 3–5, 10–15 and 25–30 m depth ranges. Additional surveys were made by SCUBA diving and snorkelling. A statistically significant effect of depth on the fish community parameters was observed, whereas differences linked to protection level, zones, sites and seasons were not significant. The abundance and frequency of occurrence of some species, particularly dusky grouper Epinephelus marginatus, were positively correlated with the degree of protection of the different zones of the marine park. Certain sites of the island are important as nursery areas for three species of the genus Diplodus (i.e., D. puntazzo, D. sargus and D. vulgaris).

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The coastal fish assemblage in the marine park of the Ustica Island was studied using underwater visual census. Seasonal surveys were conducted from May 1996 to March 1997 at several sites located within three zones of the reserve, each characterized by different levels of protection (integral reserve, general reserve and partial reserve). Visual strip transects were conducted using SCUBA at three different depth (3-5 m; 10-15 m; 25-30 m). Species richness and diversity indices were better correlated to depth than to protection level. Oppositely, size and/or abundance of some vulnerable species (e.g., Epinephelus marginatus, Labnis merula, Labrus viridis) were positively correlated with degree of protection and the so-called 'reserve effect'. These observations stress the importance of protection measures for littoral fish assemblages and represent the only available data for an Italian marine park of considerable extent.

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