Diversity and distribution pattern of the infralittoral green macroalgae at Potiguar basin, Rio Grande do Norte, Northeastern Brazil were analyzed from material collected at depths varying from 2 to 100 m. Collections were carried out with two types of dredges during four campaigns: July 2002, May and November 2003 and May 2004 at 43 stations. Chlorophyta is represented by 54 species, five varieties and three forms. The most representative family is Caulerpaceae, and the most diverse genus is Caulerpa, with 11 species. The results showed that most taxa (89%) are rare, and 10% are present at low frequencies. The most frequent species was Caulerpaprolifera (Forssk.) J.V. Lamour. occurring at almost all coastal and inner shelf stations, recorded in all campaigns. Species distribution by depth range showed that higher species number occurred on the inner shelf from 10 to 20 m, and a wide vertical distribution pattern was registered for Anadyomenestellata (Wulfen in Jacq.) C. Agardh,Chamaedoris peniculum (J. Ellis & Solander) Kuntze, Codium isthmocladum Vickers, Microdictyon sp., Udoteaoccidentalis A. Gepp & E. Gepp and Ventricaria ventricosa (J. Agardh) J.L. Olsen & J.A. West. Four species, Cladophoracoelothrix Kütz., C.ordinata (Børgensen) C. Hoek, Caulerpellaambigua (Okamura) Prud'homme & Lokhorst and Halimedasimulans M. Howe, were recorded for the first time in Rio Grande do Norte.

The main objective of the present study was to know the diversity and biomass spatial distribution of Phaeophyceae in the reef region of the Suape Port Industrial Complex (Pernambuco, Brazil). The studied material was collected in 6 (six) sampling stations, in two steps, the first between 1996 and 1999 and other on January e July of 2009 (dry and Rainy season respectively) demarcated according to the topography and distance from the port. In the laboratory, samples were sorted and fixed in formalin 4%, neutralized with borax. The taxonomic identification was based on the observation of external and internal morphology. 27 taxa belonging to 4 orders (Ectocarpales, Scytosiphonales, Dictyotales and Fucales) and five families (Chnoosporaceae, Ectocarpaceae, Scytosiphonaceae, Cystoseiraceae and Sargassaceae). Through the similarity analysis it was observed two distinct groups depending on the proximity of the port, this data were supported by permanova. The biomass of Phaeophyceae species varied from 0.001 ± 0.01 (rainy season) to 77.410 ± 3.87 g. m -2 (dry season). The species of Sargassum genus were most abundant in the area. The Phaeophyceae diversity at Suape was low, and increased with the distance from the Port and decreased during the rainy season. The area can be considered resilient because, despite of the existing impacts, species of Phaeophyceae were well represented in the area, which indicates a great capacity of the ecosystem of recovery after 30 years of the Port installation.

Due to many biotic and abiotic factors that affect the organisms distribution in the intertidal zone, this study assessed the intertidal benthic seaweed distribution and zonation in a reef section of Brazilian northeast. The data were obtained from transects taken in right angle to the coastline, during three sampling efforts in dry and rainy seasons. The frequency of occurrence of some algae such as Centroceras sp., Gelidiella acerosa, Laurencia dendroidea, Palisada perforate, Padina sp Sargassum sp., Sphacelaria sp. and Ulva sp. represent their capacity to tolerate environmental stress, which they are susceptible. The most frequent macroalgae can be found at any place along the 10 m transect. However there is a preference for some zones where the algae are grouped forming two distinct zones during the dry season. In the rainy season there is a loss of this patterne.Key words: algae zonation, diversity, benthic distribution RESUMOFrente a diversos fatores bióticos e abióticos que afetam a distribuição dos organismos na zona entremarés, o presente estudo avaliou a distribuição e a zonação das macroalgas bentônicas do mesolitoral em um trecho recifal do nordeste brasileiro. Os dados foram obtidos a partir de transecções traçadas perpendiculares à linha de costa, durante três campanhas amostrais no período seco e chuvoso. A freqüência relativa de algumas algas tais como Centroceras sp., Gelidiella acerosa, Padina sp., Palisada perforata e Ulva sp. representa bem a capacidade de tolerância ao estresse ambiental ao qual estão sujeitas, visto que elas apresentam ampla distribuição espacial e temporal ao longo do transecto de 10m. Entretanto, durante período seco estes táxons são responsáveis pela formação de dois grupos em função do gradiente de distância analisado e no período chuvoso há perda deste padrão.Palavras chave: algas, zonação, diversidade, distribuição do bentos INTRODUÇÃODiversos fatores abióticos (e.g. variação do nível de maré, grau de exposição às ondas, inclinação do substrato, dessecação e sombreamento) e bióticos (e.g. predação, herbivoria e competição) são conhecidos por afetar a distribuição dos organismos na zona entre marés (BENEDETTI-CECCHI et al., 1997). Dentre tantas, uma das características físicas mais importantes é a complexidade topográfica de um substrato, particularmente na região entre marés onde a comunidade de macroalgas está sob a pressão mecânica das ondas e sujeita à exposição ao ar (JACOBI et al., 1996). A heterogeneidade do substrato pode modificar o padrão hidrodinâmico específico durante a maré alta influenciando no sombreamento, e na intensidade