Effects of substrate on the artificial reef fish assemblage in Santa Eulalia Bay (Ibiza, western Mediterranean)

We studied the fish assemblage on an artificial reef southeast of the island of Ibiza (western Mediterranean) in relation to the type of substratum on which reef units are deployed: Posidonia meadow or bare sand. Data were collected by visual census over the course of 2 years. Species richness and abundance were determined for the total assemblage and for separate guilds, as well as their size composition. Mean species richness was higher on meadow units because of the large number of species belonging to the Labridae. The results indicate that most species are habitat-specific. Comparing these results with those from another reef in Balearic waters highlights the effect of a Posidonia meadow on reef colonization. (C) 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.