Spatial and seasonal distribution of seaweeds on coral reefs from southern Bahia, Brazil

Abstract

Macroalgae are major components of Atlantic shallow coral reef communities and potentially a major competitor with corals. This study investigates the spatial and seasonal distribution of macroalgal species, which includes fleshy algae, turf algae and some geniculate and non-geniculate corallines, on two inshore and one offshore reef from Porto Seguro Bay, Brazil. Data were collected during the dry season (July/August 1999) and the rainy season (February/March 2000), with samples being taken from the reef slope (at 1, 3 and 5 m depth) and from the reef flat. Macroalgal cover ranged from 33% (reef slope) to 60% (reef flat) on the nearshore reefs, and from 36% (reef slope) to 50% (reef flat) on the offshore reef. The largest number of infrageneric taxa was recorded during the rainy season (February/March 2000), the most abundant genera being Sargassum, Padina, Dictyota, Dictyosphaeria, Caulerpa and Amphiroa. Two species were recorded for the first time in the region: Tricleocarpa cylindrica (Rhodophyta, Galaxauraceae) and Avrainvillea longicaulis (Chlorophyta, Udoteaceae). Algal turf dominated the community structure at all reef sites and habitats. Fleshy algae are the second most conspicuous group on the reef flat in both inshore and offshore reefs. On the reef slopes, corals and zoanthids are second to turf algae in the offshore reef and nearshore reefs respectively.