Macroalgae And Associated Fauna Diversity at Bhuigaon Beach, Vasai, MH, India: A Baseline for Sustainable Coastal Management

Abstract The intertidal zones of the western Indian coast are ecologically rich habitats where macroalgae serve as key structural elements, supporting diverse faunal assemblages. This study aimed to assess the diversity and abundance of macroalgae-associated fauna along the rocky intertidal stretch of Bhuigaon Beach, located in Vasai, Palghar District, Maharashtra. Field surveys were conducted during the lowest low tides of April, May, and June 2025, using a 1 m² quadrat sampling method across vertical tidal gradients. A total of 18 faunal species were recorded, predominantly from the phyla Mollusca, Arthropoda, and Cnidaria. Species such as Nerita, Clibanarius infraspinatus, and Pennaria disticha were the most abundant, while others like Doriospella and Amphipods were limited in occurrence. The associated macroalgae observed at the site—Sargassum, Ulva, and Enteromorpha—appear to influence faunal composition by offering food, substrate, and shelter, aligning with earlier findings on the role of macroalgae in enhancing intertidal biodiversity (Azhagu et al., 2017; Apte et al., 2010). One-way ANOVA revealed significant differences in species abundance across taxa (F(17,36) = 4.61, p < 0.001), indicating non-random distribution patterns. Abundance declined notably in June, likely due to early monsoon conditions, reduced visibility, and seasonal breeding behavior among decapods and gastropods (Bhave & Apte, 2011; Datta et al., 2010). These temporal shifts highlight the need for seasonally distributed biodiversity assessments to account for phenological variation. This study not only documents the underexplored faunal richness of Bhuigaon Beach but also emphasizes the ecological importance of macroalgal habitats in supporting intertidal biodiversity. The baseline information generated through this study can contribute to future ecological monitoring, conservation and sustainable management of coastal ecosystems. Sustainable coastal development requires the conservation of biodiversity and ecological functions of such habitats, making localized biodiversity assessments important for long-term coastal planning and management.