Benthic marine algae of the coral reefs of Brazil: a literature review

Abstract

In Brazil, algae in coral reef environments can be found from Maranhao to Bahia State and there are today around 700 taxa, of which 78% are found on reef formations. The Rhodophyta are among the most common taxa found. Corallinales are the least studied group, in spite of their role in the formation and maintenance of Brazilian coral reefs. The species richness of algae on coral reefs is low in comparison with other coastal habitats, but there is an abundance of turf and fleshy macroalgae on certain parts of the coastal reefs. Halimeda spp., Dictyota spp., Dictyopteris spp., Hypnea spp., Gracilaria spp., Gelidium spp. and Sargassum spp. are some of the most conspicuous algae, while Caulerpa and Udotea and seagrasses are frequently found on unconsolidated sandy bottoms. Benthic marine algae are important components of shallow coral-reef communities in the Atlantic and they can be regarded as major competitors to corals. Over the last two decades, numerous cases of phase shifts from coral to algal predominance over coral reefs were reported worldwide. These reports coincide with the increasing concern with reef degradation, mainly attributed to anthropogenic nutrient enrichment and overfishing. In Brazil the effects of nutrification over coral reef dynamics are only recently being assessed, and crucial basic information is still lacking. The exploitation of marine algae, mainly of Gracilaria, is also recent in Brazil. Macroalgae growth in some disturbed Brazilian reefs were associated with grazing reduction caused by overfishing or nutrification. Rapid assessments of coral reef flora are needed in order to generate reliable information for environmental