Comparative Assessment of Intertidal Macrofaunal Assemblages between Rocky and Muddy Shores in the Gulf of Khambhat, Gujarat, India

Abstract

The dynamic intertidal zones of the Gulf of Khambhat, Gujarat present a mosaic of habitats shaped by pronounced tidal regimes and varied substrate compositions. This study provides a comprehensive comparative analysis of macrofaunal assemblages across two ecologically distinct intertidal sites: the rocky coast at Gopnath and the muddy flats at Koliyak from year April 2024 to March 2025. Using standardized quadrat-based sampling across five assemblages (refers specifically to the biological communities) three at Gopnath coast and two at Koliyak coast, a total of 55 species of macrofauna spanning six phyla Mollusca, Arthropoda, Annelida, Nemertea, Cnidaria, and Chordata were documented. Rocky intertidal habitats at Gopnath supported higher species richness and taxonomic diversity, particularly among mollusks and crustaceans, in contrast to the relatively less diverse communities at Koliyak. Using biodiversity indexes including Shannon– Wiener, Simpson’s diversity, and Pielou’s evenness, the ecological health and community structure of intertidal macrofaunal assemblages were evaluated. The findings showed distinct substrate- driven variations in community composition, with greater species diversity and evenness on rocky coasts as opposed to muddy shores. Additionally, cluster analysis highlighted habitat-specific biological trends by revealing distinct assemblage groupings between Koliyak and Gopnath The findings demonstrate how habitat variability shapes coastal biodiversity and offer crucial baseline information for Gulf of Khambhat protection and management.