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A B S T R A C TThe video-transect method consists of a field survey performed with a video-camera along a line of fixed length, with the registered images further analyzed using a computer. This method was successfully applied in Brazil for the first time in the coral reefs of Todos os Santos Bay. The main goal of this work was to define the minimum sampling effort needed to describe the coral community when the video-transect method was applied to a selected reef site, namely the Pedra do Silva Reef in the Itacolomis reef complex, inside the Corumbau Marine Extractive Reserve, in Southern Bahia. Each transect was analyzed throughout its length, in successive captured video frames. The findings revealed that six 20 m long transects with an analysis of twenty points per image (frame) was sufficient for sampling the broad taxonomic categories of hard corals and major reef benthos, and that the whole field operation could be performed during one dive per station. R E S U M OO método do vídeo-transecto consiste em uma filmagem do fundo marinho ao longo de uma seção linear, e as imagens são posteriormente analisadas, em laboratório, na tela de um computador. Este método foi aplicado pela primeira vez no Brasil nos recifes do interior da Baía de Todos os Santos, com resultados satisfatórios. O objetivo deste trabalho foi determinar qual seria o menor esforço amostral na aplicação do vídeo transecto para avaliar a comunidade de coral do recife Pedra do Silva, no complexo de recifes dos Itacolomis, na Reserva Extrativista Marinha de Corumbau, no sul do estado da Bahia. Cada transécto foi analisado em toda a sua extensão em quadros sucessivos gerados com o congelamento da imagem na tela de um computador. Os resultados obtidos apontam o número de seis transéctos de 20 m de comprimento para uma análise de vinte pontos por quadro como adequada para a identificação taxonômica das principais categorias dos corais construtores e dos componentes da biota bentônica dos recifes, podendo toda a operação ser executada durante apenas um mergulho por local de amostragem.

There is at present a ‘coral reef crisis’; one of the more drastic consequences of this is a phase shift, in which reef‐building corals are replaced by non‐reef building benthos such as macroalgae and soft corals. Previous studies have principally focused on the shift to macroalgae. Our goal was to investigate whether the dominance of the zoanthid Epizoanthus gabrieli on some reefs of Todos os Santos Bay, Brazil, represented a non‐algal phase shift. In 2003, we identified a high cover of this species on two reefs (52% and 70%), but only in 2007 was it possible to confirm a reduction in coral cover. This dominance has persisted for over 9 years, characterizing a true phase shift. This loss of coral cover may be a result of anthropogenic disturbances within the bay; however, given the large number of human impacts, further studies are needed to identify specific causes of this shift. Although there are some reports of phase shift involving species pertaining to the Class Anthozoa, this is the first report of this phenomenon involving the order Zoanthidea.