How herbivory and predation on benthic recruits affect the Coral-Algae interaction along Alcatrazes island and the coastal adjacent area?

Abstract

Reef environments are threatened by anthropogenic pressures such as overfishing and eutrophication. Those activities can change benthic communities, increasing algae abundance and biomass, excluding corals species. Algae dominate most rocky shores on the north coast of Sao Paulo, except for Alcatrazes Island where corals and herbivore reef fishes are very abundant. This project aim to describe the benthic communities along the gradient between the Alcatrazes Island and the coastal area. Our hypothesis is that corals are more abundant in Alcatrazes where the oligotrophic waters and herbivory pressure restrict algae growth. Using stable isotopes we will check the throphic structure between producers, detritus and their consumers in the different localities. The importance of consumers for the structure of the community will be tested by experiments in-situ excluding potential herbivores (urchins and fishes). To check how the composition of the community (algae or corals) determine the benthic community establishment, experiments in-situ excluding predators on recruits will be also done. The new information provided by this study will contribute to understanding the functioning of subtidal communities in subtropical rock shores and to identify potentials key interactions in the management and conservation of reef ecosystems. (AU)