Investigating of Biological Health of Mangrove Forest in Nayband Bay Using Macrobenthic Communities

The purpose of this study is to survey the ecological health of mangrove forest in Nayband bay by Shannon diversity index and determine the environmental factors effective in distribution of macrobenthic. 6 transects along coasts of Nayband bay were sampled for macrobenthos identification and enumeration. In each transect 3 stations were selected in perpendicular line to the beach. Physicochemical parameters such as Temperature, Salinity, Turbidity, Phosphate, Nitrate, Chlorophyll etc. were measured in addition to sediment grain size and TOM. Totally 60 macrobenthos species identified. Gastropods and Bivalves in Mollusca phylum were the dominant group with the contribution 48% of total macrobenthos population.  Pirenella cingulata and Protapes gallus were the dominant species in Gastropods and Bivalves respectively. Maximum average total numbers of benthos were 5361.56 and 5584.78 individual/m2 in winter and summer respectively and minimum average number was 1957.56 individual/m2 in spring. Parametric statistical tests showed significant difference between number and frequency of species in different seasons and station (p<0.05). CCA analysis showed that salinity, turbidity and TOM are an effective factors in distribution of crustacean and bivalves. Phosphate, silt & clay and chlorophyll a have positive impact and sand present and temperature have negative impact on distribution of Gastropods. Temperature is important factor on density of polychaetes. Shannon diversity index showed that the studied area is moderate in terms of biological health.