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Note:

Samples of Porites porites rubble were collected from across three fringing reefs which lie along a eutrophication gradient in Barbados, West Indies. The coral skeleton fragments were examined for clionid sponges. Data collected from the reef crest and fore reef zones and from across the range of distances and depths were pooled for each reef to compare indices of sponge abundance along the eutrophication gradient. Significant differences between the reefs were found for the proportion of rubble invaded (ANCOVA, p = 0.004), number of invasions per sample (ANCOVA, p = 0.002), and number of species per sample (ANCOVA, p = 0.018) but not for total surface area of sponge invasions per sample (ANCOVA, p = 0.064). All the indices demonstrated an increase with increasing eutrophication level. Clionids were found in nearly twice as many of the pieces collected from the most eutrophic site (41%) as from the least eutrophic (24%). Since clionids may be the principal bioeroders of coral reefs, an increase in their abundance due to excessive pollution likely results in greater bioerosion of affected reefs. The mean abundance of Type 3 corals was found to be positively related to the frequency of boring sponge invasion, suggesting that increased bioeroision may be partly responsible for community shifts toward Type 3 corals in polluted waters. One new variety and three new species of boring sponges of the genus Cliona were found. A new variety of C. amplicavata Rutzler is described, Cliona species 2 of MacGeachy is redescribed and Cliona species 4 and Cliona species 5 are described for the first time. Cliona species 5 may become an important bioeroder in Barbados and other Caribbean islands since it flourishes under high eutrophic conditions which are beginning to plague West Indian reefs. (Abstract shortened by UMI.)

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