Comparative Study of Population Structure and Ecological Indices of Macrobenthos in the Coasts of Chabahar Bay (Oman Sea, Iran)

Abstract

Introduction: Macrobenthos play a fundamental role in energy flow and nutrient cycling within marine ecosystems. Both biotic and abiotic factors determine the presence and distribution of macrobenthic communities. The coasts of Chabahar Bay, due to their diverse muddy, coral, rocky, sandy, and mangrove habitats, as well as high temperatures and habitat heterogeneity, represent rich and diverse ecosystems. Since these areas are influenced by human activities such as fishing, their direct and indirect impacts have extended to deep and offshore waters. Therefore, the present study was conducted to investigate the population structure of macrobenthos along the coasts of Chabahar Bay. Materials & methods: To identify, quantify abundance and density, diversity, and dominance of macrobenthic communities in the coasts of Chabahar Bay, sampling was conducted in three transects or regions: northern Chabahar Bay, Tis, and Konarak during two seasons (warm and cold). Sampling was performed using a Van Veen grab with a sampling area of 0.04 m² at depths ranging from 1 to 4 meters, with a total of 81 replicates. Environmental variables including salinity, temperature, turbidity, pH, electrical conductivity (EC), and organic matter content of the sediment were also measured. Identification of macrobenthic samples was carried out using a stereomicroscope. Results: The study results clearly demonstrated differentiation in population structure among the three regions. Taxa contributing to this divergence and dominant taxa in the macrobenthic communities belonged to diverse groups of macrobenthos, with the class Malacostraca (Crustacea) exhibiting the highest abundance among macrobenthic groups. The northern Chabahar Bay region showed superiority in terms of abundance and dominance, while the Konarak region had higher diversity compared to other regions. Among the environmental parameters, only electrical conductivity (EC) and salinity of the ambient water showed significant and strong correlations with the three studied regions along the coasts of Chabahar Bay. Conclusion: Overall, understanding the population structure of macrobenthos along the coasts of Chabahar Bay, the influencing environmental and ecological factors, and the status of habitat diversity in these ecosystems in relation to their constituent components is essential and crucial for the future management and conservation of the related marine ecosystems.