10.1016/s0967-0653(97)83012-8

The density and diversity of shallow-water groupers at Gaagandu, North Male Atoll and Olhugiri, Thaa Atoll, Republic of Maldives was enumerated using visual transects. Four different habitat types were surveyed: reef lagoon, reef crest, reef slope, and a well developed lagoonal reef. Twenty-two species in seven genera were recorded. Median densities ranged from 7 to 23 grouper 240 m-2. At Gaagandu Island, the reef slope was repeatedly sampled using 20-m belt transects to estimate the efficiency and accuracy of the sampling methodology. Fifteen transects were necessary to estimate the median density of all species within 10% of the reference value and to develop a species list containing 80% of the total number of species observed. The species observed varied in their degree of site attachment. Those species which were most closely tied to their habitat exhibited clumped spatial distributions while those species which 'roamed' over large areas had random spatial distributions. The number of transects necessary to adequately characterize the median density of a species was related to the degree of clumping in its spatial distribution.