Composição e estrutura das comunidades de macroalgas do infralitoral do Arquipélago de Fernando de Noronha, Pernambuco - Brasil, com ênfase nas calcárias incrustantes

Abstract

A good interpretation about the components and the origin of the Brazilian flora requires fundamentally that this knowledge is also based on the survey of algae from oceanic islands and subtidal zone. The little information about the flora from oceanic islands is an issue of concern considering the fragility of algal communities on these ecosystems due to their limited area and distance from the continent. Another aspect still to be understood about the subtidal zone is related to the qualitative analyses of the incrusting coralline algae. Two expeditions were made and 19 sampling sites on the subtidal zone were selected based on the diving maps of the archipelago, among which 13 sites on the protected side and 6 sites on the exposed side. At each site, sampling was performed at different isobaths (0 to 28 meters). The first manuscript describes the survey on the incrusting coralline algae diversity that colonises the subtidal region of the Fernando de Noronha Archipelago, presenting descriptions of three species: Sporolithon episporum (M. Howe) E.Y. Dawson (Sporolithaceae), Mesophyllum erubescens (Foslie) Me Lemoine (Hapalidiaceae) and Lithophyllum stictaeforme (Areschoung in J. Agardh) Hauck (Corallinaceae). The second presents an evaluation of the structure and composition of the subtidal communities, where 48 species are registered, including ten new additions for the Brasilian oceanic islands. Phaeophyceae presented the highest visual cover while Rhodophyta presented the smallest, 44% and 0.4% respectively. The studied area may be altered due to natural disturbance, probably caused by herbivory.