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

The diversity and spatial distribution of mollusks in three different mangrove zones (deltaic mangrove, island mangrove and coastal mangrove) of Hara Biosphere Reserve were studied from August 2014 to January 2015. A total of 9 transects (27 stations) perpendicular to the coastline were selected to cover all over the study area. Counts of all macrofauna 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 were found and listed. Results from the two-way ANOSIM suggested that molluscan assemblages presented significant spatial and temporal variations in different mangrove habitats. In addition, using non-metric multidimensional scaling (nMDS) ordinations of the assemblage compositions showed some separation between three mangrove zones. Results from benthic samples illustrated that deltaic zone had the highest abundant and diversity and coastal zone had the lowest values among the three zones. In conclusion, different hydrological conditions, temperature, salinity and sediment texture were the main factors determining dispersion of molluscan faunal communities in different mangrove habitats at Hara Biosphere Reserve. This result implied that the different mangrove habitatshad different effects on the macrofauna communities and shed light on the macrofauna adaptation capability to specific habitats.