Caracterização da comunidade e identificação da distribuição dos grupos funcionais de macroalgas do recife de Maracajaú-RN

Abstract

Coral reefs integrate the major productivity and species richness ecosystems in the planet, provide ecosystem services that thousants of people depend on. Macroalgae are important in these enviroments and may be utilized as bioindicators. The presente study caracterized the seaweed community of Maracajau reef (5°24'40" S - 35°18'40" W). Four stations were defined to data collect (E1: Inside border; E2: Reef center; E3: Tourism utilization area; E4: Outside border). The photoquadrat method was applied to register images of marine flora along transects (45 images on each station). The present macroalgae in each image was identified at taxonomic level of gender. A similarity analyisis was performed (Jaccard Index) and the CPCe 4.1 software was utilized to obtain cover of macroalgae functional groups in each station. A total of 13 genders of macroalgae were identified, Dictyopteris, Dictyota, Padina, Sargassum, Lobophora, Udotea, Caulerpa, Gelidium, Octhodes, Gracilaria, Laurencia, Jania and Lithothamium. The detected functional groups were foliose, leathery, corticated, articulated calcareous and crustose algae. A seagrass species (Halodule wrightii) and other organisms were identified. The E1 is covered mainly by foliose macroalgae (20,18%) and seagrass (34,3%). The E2 presented the major foliose macroalgae coverage (49,35%), crustose calcareous algae (17,78%) and Turf (13,78%) were also representatives groups. The tourism area (E3) showed Turf (26,62%) and foliose macroagae (24,51%) coverage, however soft coral Palythoa caribaeroum had the major percentage (40,98%). The composition of outside border (E4) presented calcareous crustose algae (53,30%), foliose algae (11,02%) and leathery algae (9,43%). The Jaccard Index showed that E2 and E3 presented major similarity (0,714). The outside border is more similar with E3 (0,625) and E2 (0,5) than inside border, E1 (0,214). The E1 showed lowest similarity with the others. The morfofunctional groups as leathery and crustose calcareous algae occurred mainly in the outside border, revealing more tolerance from waves and currents disturbance. The foliose algae occurred along the entire reef, however the central area without tourism showed major flora from this group. The outside border presented major abundance of corticated algae. The flora showed differents compositions along the Maracajau reef, that changed according to substrate and hydrodynamics.