Spatial Distribution and Quantitative Assessment of Seagrass Meadows in the Marine National Park and Sanctuary, Gujarat, India

Abstract The present study assessed the spatial distribution and quantitative attributes of seagrass meadows in the Marine National Park and Sanctuary (MNP&S), Gujarat, using remote sensing, GIS and field-based quadrat sampling during February–March 2025. LISS-IV imagery (5.8 m spatial resolution) was used to delineate seagrass distribution, followed by field verification. A total of 103 quadrats were sampled across five islands to assess species composition, leaf-pair density, abundance, frequency, relative composition and canopy cover. Three species, Halophila ovalis, Halodule uninervis and Halophila beccarii, were recorded. The mapped seagrass extent was 787.80 ha (7.88 km²), with the largest extent occurring in the Bhaider–Noru–Chank–Mitha-Khara Chusna–Tam Reef group (503.22 ha). Halophila ovalis was the most widespread species, occurring at all five sampled islands. Its highest leaf-pair density was recorded at Narara (499.33 leaf pairs m⁻²), while maximum canopy cover was recorded at Dhani (21.85%). Halophila beccarii, a Vulnerable species, was restricted to Dedeka-Mundeka, Dhani and Pirotan. The present assessment provides a contemporary baseline for seagrass distribution and species-level ecological attributes in the MNP&S. Differences from earlier estimates indicate the need for standardized, repeatable monitoring before temporal decline can be conclusively established.