Exploring the Interplay Between Phytoplankton Taxonomy, Pigments, and Optical Properties in Ratnagiri Coastal Waters using a Multi-Parameter Approach

Abstract This study presents a comprehensive analysis of phytoplankton diversity and optical properties in the coastal waters of Ratnagiri, India. Ratnagiri, located on the southern coast of Maharashtra, is one of the major centre for fishing activities in India as well as a developing hub for industrial activities. Given its ecological significance and the pressures it faces, the coastal waters of Ratnagiri present a valuable case for studying phytoplankton dynamics and their optical properties. We integrated multiple parameters, including phytoplankton taxonomy, pigment composition, coloured dissolved organic matter (CDOM), and absorption characteristics to provide a holistic view of the phytoplankton community and its optical environment. Phytoplankton samples were collected across various sites in Ratnagiri and analyzed using advanced microscopy and high-performance liquid chromatography for taxonomic identification and pigment profiling. CDOM and absorption properties were measured using spectrophotometric methods. Our findings reveal more or less spatial uniformity in phytoplankton composition, with significant diversity within the phytoplankton community. Pigment analysis identified key marker pigments corresponding to various phytoplankton classes majorly bacillariophytes (diatoms), chlorophytes, cyanophytes, haptophytes and cryptophytes. facilitating a deeper understanding of community structure. CDOM analysis indicated varying levels of dissolved organic matter, influencing light absorption and availability in the water column. The absorption data highlighted the specific wavelengths most affected by phytoplankton presence, notably those contributed by diatoms and cyanophytes, providing insights into the optical properties of Ratnagiri's coastal waters. This integrative approach underscores the importance of considering multiple parameters to accurately assess phytoplankton dynamics and their impact on the aquatic environment. The results contribute to a better understanding of the ecological processes governing coastal waters in Ratnagiri and offer valuable information for future monitoring and management efforts.