THE STRUCTURE OF SUBTIDAL MACROALGAL ASSEMBLAGES AT THE TAMOIOS ECOLOGICAL STATION, A THREATENED CONSERVATION UNIT IN RIO DE JANEIRO, BRAZIL

The structure of subtidal rocky bottom communities at Tamoios Ecological Station (TES), situated in Ilha Grande Bay, Rio de Janeiro State, as well as in other Brazilian marine protected areas, is insufficiently characterized. The present study describes the macroalgal assemblages of shallow subtidal rocky bottoms on two islands of the TES-Imboassica (IM) and Búzios Pequena (BP)adopting species and genera as observational units. Two sites were surveyed on each island in summer 2011. Random 30x30 cm quadrats (n=3) were scraped to collect all macroalgae except crustose species. The subtidal assemblages, in which 58 macroalgal species occurred, were characterized by the high frequency and percent cover of Sargassum vulgare C. Agardh (56.8±8.4%). The sites differed significantly in total number of species and Shannon-Weiner diversity index (PERMANOVA, p<0.05). According to SIMPER, the macroalgal genera that most contributed to the dissimilarities of cover between the sites (contribution >5%) were Sargassum, Laurencia, Wrangelia, Canistrocarpus, Asparagopsis, Hypnea, Ceratodictyon, Gayliella, Spyridia and Chondria.Dissimilarities within and between the islands, as shown by nMDS of the cover data, suggest that different spatial scales should be considered in monitoring the rocky bottom communities of Ilha Grande Bay.

位于里约热内卢州格兰德岛湾的塔莫伊奥斯生态站（Tamoios Ecological Station, TES）及其它巴西海洋保护区的潮下带岩底群落结构，目前尚未得到充分的特征描述。本研究以物种与属作为观测单元，对塔莫伊奥斯生态站所辖的因博阿西卡岛（Imboassica, IM）与小布齐奥斯岛（Búzios Pequena, BP）的浅海潮下带岩底大型藻类群落进行了特征描述。2011年夏季，每个岛屿布设了2个调查位点；研究采用随机设置的30×30 cm样方（n=3），刮取样方内除壳状藻类外的所有大型藻类样本。本次调查共记录到58种大型藻类，该潮下带群落以普通马尾藻（Sargassum vulgare C. Agardh）的高出现频率与盖度为典型特征，其平均盖度达56.8±8.4%。各调查位点的物种总数与香农-维纳多样性指数均存在显著差异（置换多元方差分析，PERMANOVA，p<0.05）。基于相似性百分比分析（SIMPER），对各调查位点间盖度差异贡献度超过5%的大型藻类属包括：马尾藻属（Sargassum）、凹顶藻属（Laurencia）、Wrangelia属、Canistrocarpus属、Asparagopsis属、麒麟菜属（Hypnea）、Ceratodictyon属、Gayliella属、Spyridia属以及软骨藻属（Chondria）。基于盖度数据的非度量多维标度分析（nMDS）结果显示，岛屿内部与岛屿间的群落差异表明，在对格兰德岛湾的岩底群落进行监测时，需考虑不同的空间尺度。