The Survey of biological varieties and pollution of Benthic societies of Laft and Tyab firths in Hormozgan Province

In order to evaluate and compare the Benthic in Laft and Tyab firths, the samples were gathered in two different seasons (Winter and Summer), 3 stations and also 3 repetitive layers. The results show that Polychaete has the most rate of frequency in hot seasons, however, Gastropoda has the least rate of frequency in cold seasons (less than Zero). Regarding average density in the 4th station of Tyab, Macrobenthos showed a significant difference in relation to station/place and station was proven to have an impact on the density of the Macrobenthos(P<0.05). The index of Margalof and Shanon states that all the polluted areas under study were in desired condition which is normal in hot seasons. The Ounce index shows that Laft and Tyab firths are in desirable conditions and the environments are partially without pollution. Moreover, the index of Sympson demonstrated that the areas under study were not affected by serious pollution. In addition, the ecology index of frequency curve/ weight depicted that the curve weight is higher than/ above the frequency curve in all the stations which is indicative of a stress-free environment. Yet, 4th Tyab station was found to be a stressed environment regarding its geographical location which is the result of the direct effect of residuum from Shrimp-growing sites.