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Ghost shrimps (Crustacea: Decapoda) demonstrate remarkable levels of niche selection and habitat diversity. Due to their cryptic life style, interactions between ghost shrimp assemblages and environmental parameters that potentially shape their local distribution are poorly understood. In the present study, ghost shrimp assemblages from the Persian Gulf (PG) and the Gulf of Oman (GO) were investigated to assess the main drivers determining their assemblage structure along a wide niche type and at a large geographic scale. During three large-scale oceanographic expeditions, sediments samples for biological and physicochemical analysis were collected by box corer (0.1 m2) from 62 stations. The spatial distribution of collected samples was evaluated based on sediment parameters obtained on grain size, total organic content (TOM) and carbonate, as well as water parameters including pH, temperature, depth, dissolved oxygen, chlorophyll α and salinity. Our results indicated a biodiversity hotspot for ghost shrimp in the north-western part of PG and the eastern part of GO. Aqaballianassa ehsani is the most frequent species in this research. DistLM analysis revealed that the abundance of ghost shrimps in the region is significantly corelated with TOM and Sand. Furthermore, a step-wise regression model highlighted that each ghost shrimp species is influenced by specific environmental factors. Our findings provide new insight in niche preferences of the two Michaelcallianassa congeners. While water and sediment parameters play a crucial role in determining the habitat preference of M. persica , only sediment parameters specify the favored niche of M. indica. • Aqaballianassa ehsani is the most frequent ghost shrimp species in the studied area. • As Water and sediment parameters well determine the habitat preference of Michaelcallianassa persica , while mainly sediment parameters specify the favourite niche of M. indica. [ABSTRACT FROM AUTHOR]

In this study, the effects of sediment texture and total organic matter (TOM) in sediments of Gomishan Wetland on density and diversity of macroinvertebrates were studied. The sampling was carried out in spring (as water-level fall season) and summer (as water-level rise season). The wetland divided to four stations and the samples of sediments and macroinvertebrates were collected from the coast area, near the sea area and water-rise area in each station by Ekman Grab. 10 families were identified which the most abundance was belonged to Pyrgulidae. The sediment texture was different in each location, but Loam was the common texture. Results showed that except of south station, TOM increased from the north to the south of Gomishan Wetland. There were low correlations between the amounts of TOM and silt-clay of bottom sediment with the density and diversity of macroinvertebrates, but the amount of TOM is effective on the distribution of Cardiidae. Totally, the density and diversity of organisms follow complex actions. [ABSTRACT FROM AUTHOR]