Background:

Few investigations use macroalgae´s biomass as an indicator of their abundance on coral reefs, where they play an important role.

Goals:

To explore the spatial and temporal differences in the macroalgae communities in three coral reefs located along the southern coast of Cuba.

Methods:

Differences in abundance, species number, and specific composition of macroalgae were analyzed in four zones (reef lagoon and fore reef at 5, 10, and 15 m depth) in three coral reefs, in two climatic periods (dry and rainy) in 1987. The frequency of appearance, the dry biomass by species, and the dry total biomass were used as abundance indicators. Multivariate and univariate analysis were used. Relationships among these variables and some environmental characteristics (depth, substratum type, hydrodynamics, and bottom relief) of sites were examined.

Results:

67 macroalgae species and three marine angiospermae were reported. Differences in specific composition and biomass were found among sites and zones, but not between the climatic periods, with a decrease in species number when depth increases. At reef lagoons, higher biomass and frequency were found for the marine seagrass Thalassia testudinum and macroalgae Halimeda incrassata and H. simulans. At fore reefs, the most important species in terms of their biomass and frequency were Halimeda scabra and Dictyota ciliolata. Juan García reef had the highest values of total biomass and species number, probably due to the mixed substrata and the contribution of nutrients. Cantiles reef, with poorer oceanic waters, had lower total biomass. In Diego Pérez reef, the species number was lower, apparently because this location is more protected.

Conclusions:

The habitat characteristics and the decrease in light as depth increases seem to be determining factors in the distribution of the macroalgae species.