COMPARATIVE ANALYSIS OF PHYTOPLANKTON COMMUNITY STRUCTURE AND DIVERSITY AT BHATYE AND ALAWA BEACHES, RATNAGIRI, MAHARASHTRA: IMPLICATIONS FOR COASTAL ECOSYSTEM HEALTH

Lawate D. V.* and B. G. Bhaware

This study provides a detailed analysis of the phytoplankton diversity and community structure in the intertidal zones of Bhatye and Alawa (Jakimirya) beaches, situated along the Ratnagiri Coast, Maharashtra, over a three-month period from March to May 2023. Fortnightly water samples were collected during low tide from four stations at each beach, using plankton net with a mesh size ranging from 25–50 μm to capture the phytoplanktons. A total of 100 liters of water per site was filtered and preserved in 4% neutralized formaldehyde for qualitative analysis. Species identification was conducted using an electron microscope at 40X magnification, following established taxonomic references. The study revealed a total of 29 phytoplankton species from 24 genera at Bhatye Beach, and 31 species from 26 genera at Alawa Beach. The identified species were classified into three major taxonomic groups: Bacillariophyceae (diatoms), Dinophyceae (dinoflagellates), and Cyanophyceae (blue-green algae). Diatoms, particularly members of the Bacillariophyceae, were the predominant group at both beaches, with 24 species recorded at Bhatye and 25 species at Alawa. Cyanophyceae were present across all sampling stations, while Dinophyceae were comparatively less abundant.