Diversity, distribution and temporal variation in abundance and biomass of sea cucumber population in Pozm Bay, north of Oman Sea, Iran

Abstract

The ecosystem of Pozm Bay, north of Oman Sea, Iran, is one of the unique marine habitats for benthic aquatic species. Therefore, this study investigated the distribution, diversity and temporal variation in abundance and biomass of sea cucumber species in Pozm Bay. Five transects, each of them in four triplicates and perpendicular to the sea were sampled at 3, 6, 9 and 12 m depths and three seasons (winter, spring and autumn). Different spicule patterns were chosen as identification key for each studied species. A total of five species from two families of sea cucumbers were identified in the study area, in which 191 and 41/km 2 were belonged to Holothuridae and Stichopodidae with three and one species, respectively. H. leucospilota, was found to be a dominant species in Pozm Bay and had the biggest body size and biomass in winter. The most density of sea cucumbers was recorded in winter at 48.36 g/m2, while the lowest biomass was calculated at 18.02 g/m2. H. leucospilota, H. arenicola, H. atra and S. variegatus were abundant at transects 3, 1, 3 and 1, respectively. The highest and lowest density of sea cucumbers in winter were observed at transects 1 and 2, respectively. In addition, in spring, the highest and lowest density of sea cucumbers were recorded at transects 3 and 2, respectively. Shannon and Margalof ecological indices showed that all species were common in different seasons and had a contagious dispersion pattern. Moreover, it appeared that the distribution of sea cucumbers was affected by habitat complexity in the study area. Together, findings showed that the study of distribution patterns, diversity and temporal variation of sea cucumbers can deepen our knowledge about the abundance and biomass of these valuable species, which is useful in managing the fisheries resources and protective programs in Pozm Bay.