Density and Diversity of Cnidarians Medusae (Family: Eirenidae) in Bahrakan Waters (Northwestern Persian Gulf)

The purpose of this investigation was to study the density and diversity of Eirenidae in Bahrakan waters (Northwestern Persian Gulf). The Sampling was conducted in 6 stations, during July, August and October in 2010 and December, February and April in 2011, using 300μm mesh size plankton net. Environmental parameters such as salinity, pH, temperature and dissolved oxygen were measured. In this study, a total of 12 species of medusae were identified. Maximum and minimum densities of medusae were observed in July and August, respectively. Species such as Eutima variabilis, Tima flavilabris, Eutima gegenbauri, Eutima gracilis, Eutimalphes sp.1 and Irenium sp.1 were the first report in the Iranian waters of the Persian Gulf. The result of Correlation showed that the distribution of medusaes has more correlated with temprature. Analysis variance test were used to show impact of times on medusae abundance. As a result, medusae abundance showed significant variation in different months. The Shannon diversity index, ranged between 0.22 and 1.79, was maximum in July.