Abstract
The distribution and abundance of azooxanthellate coral Tubastraea Lesson, 1829 were examined at different depths and their slope preference was measured on rocky shores on Ilha Grande, Brazil. Tubastraea is an ahermatypic scleractinian nonindigenous to Brazil, which probably arrived on a ship's hull or oil platform in the late 1980's. The exotic coral was found along a great geographic range of the Canal Central of Ilha Grande, extending over a distance of 25 km. The abundance of Tubastraea was quantified by depth, using three different sampling methods: colony density, visual estimation and intercept points (100) for percentage of cover. Tubastraea showed ample tolerance to temperature and desiccation since it was found more abundantly in very shallow waters (0.1-0.5 m), despite the fact that hard substratum is available at greater depths at all the stations sampled. At most sites, 1 to 5 colonies per 0.25 m2 were found most frequently, but occasionally more than 50 colonies were found per 0.25 m2, indicating a somewhat gregarious spatial distribution for this coral. The coral Tubastraea was found to occupy slopes of every possible angle in the Canal Central of Ilha Grande, but more colonies were found occupying slopes of 80 to 100 degrees. Therefore, its insensitivity to angles of recruitment and its tolerance for different depths makes it an organism with great ecological tolerance, with a potential to colonize new areas and increase its current range in Brazil's coastal waters.
Highlights
Much attention has focused on the introduction of several marine species recently (Grosholz & Ruiz, 1996; Johnson & Carlton, 1996; Crooks, 1998), biological invasions in marine systems have been neglected (Carlton & Geller, 1993)
Tubastraea was found over a substantial geographical range on the rocky shores of Canal Central in Ilha Grande, extending from Ponta do Acaiá to Ilha do Morcego, a distance of 25 km
The global movement of organisms associated with seafaring vessels and with commercial fishery products have redistributed a vast number of marine organisms
Summary
Much attention has focused on the introduction of several marine species recently (Grosholz & Ruiz, 1996; Johnson & Carlton, 1996; Crooks, 1998), biological invasions in marine systems have been neglected (Carlton & Geller, 1993). To understand the possible impacts of an introduced species on an established community and predict its potential for establishment and range expansion to new areas, quantitative and experimental studies are needed (Carlton, 1996). These should identify the ecological preferences of exotic species so that their potential for new invasions can be inferred
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