INTERACTIONS BETWEEN HYDROLOGY AND BENTHIC COVERAGE AT ROCAS ATOLL

Abstract

Abiotic parameters and benthic coverage were determined in shallow habitats at Rocas Atoll. It was found daily and seasonal variations on seawater characteristics related to tides, pluviometry, daily solar cycle, and organisms’ metabolism. Habitats with high coverage of carbonatic organisms were associated with the alkalinity of seawater, whereas habitats with elevated abundance of turf and macro algae were correlated to dissolved inorganic nutrients. Therefore, it is suggested that the availability of nutrients and carbonates in seawater are important for the organism’s distribution in the atoll. Only seven corals settled on the plates during the experiment (Porites spp. and Siderastrea spp.). In order to better constrain the causes of the low coral recruitment in the atoll and predicted the effects of climate changes and ocean acidification over this important reef ecosystem, it is necessary to assess, in high resolution (i.e. week to monthly), the environmental variables that overlaps a short-term period. Keywords: macroalgae; coral reefs; dissolved inorganic nutrients; environment variables.