Patterns of mollusks (Bivalvia and Gastropoda) distribution in three different zones of Harra Biosphere Reserve, the Persian Gulf, Iran

Document Type : Research Paper


1 Islamic Azad University Science and Research Branch Hesarak, Tehran, Iran, IRAN, ISLAMIC REPUBLIC OF

2 faculty of natural resource. tehran university, karaj, iran


The diversity and spatial distribution of mollusks and their relationships between physico-chemical parameters of the water (temperature, dissolved oxygen, salinity and pH) and sediments texture (sand, silt-clay and TOM) in three different mangrove zones (deltaic mangrove, island mangrove and coastal mangrove) of Harra Biosphere Reserve were studied during two sampling seasons (August 2014 and January 2015). A total of 9 transect (27 stations) perpendicular to the coastline was selected to cover all over the study area. Counts of mollusks (bivalvia and gastropoda) with three replicate sediment samples were recorded from each zone and station. In this study, 32 different species of mollusk including 8 bivalves and 24 gastropods have been found and listed. Deltaic mangrove zone had more total abundance (636±342 ind m-2) than all the other mangrove zones sampled and dominated by white clam (Dosinia alta) and snails (Cerithidea cingulata and Asseminea sp). Results from the two-way crossed ANOSIM showed that molluscan species composition (bivalvia and gastropoda) differed among various seasons and mangrove zones. Results from benthic samples illustrated that deltaic zone had the highest diversity (Shannon Wiener diversity: 1.45) and coastal zone had the lowest values (1.03) among these three zones. In conclusion, sediments texture, temperature, salinity and pH were the main physico-chemical factors determining dispersion of molluscan faunal communities in the study area. This result implied that the different mangrove types had different effects on the molluscan communities (bivalvia and gastropoda) at Harra Biosphere Reserve.