The Netravathi-Gurupura estuary is a tropical, micro to meso-tidal estuary situated at Mangalore, southwest coast of India. The estuary outlets into the Arabian Sea and it is regarded as one of the major upwelling systems of India. Our study focusses on the seasonal phytoplankton succession in Netravathi-Gurupura estuary through studying the hydrochemical and hydrobiological physiognomies of riverine, estuarine and marine components. Hypoxic conditions prevailed at the estuarine zone during monsoon seasons (D.O.< 3 mg L⁻¹). Salinity was very low in the estuarine and marine zone during the 2018 monsoon season and hefty silicate loadings (>100 μmol L⁻¹) contributed to the proliferation and blooming of diatoms like Skeletonema costatum in the estuary. A strong negative correlation between phytoplankton composition and silicate was observed during the 2018 monsoon season (r = −0.977). The substantial entrainment of TDS (>10000 ppm), relatively higher salinity (33–35 psμ) and high values of TN: TP (42.0–67.0 μmol L⁻¹) and proliferation of dinoflagellates were the characteristics of non-monsoon seasons. A significant positive association of phytoplankton was observed with NO3 (r = 0.989) and TN: TP (r = −0.997). In terms of phytoplankton species diversity, our study classifies estuarine zone as least diverse zone, particularly during the 2018 monsoon season (D > 0.55, 1/D < 1.82). Phytoplankton succession from diatoms (monsoon) to dinoflagellate (non-monsoon) is attributed to the alteration in physic-chemical and nutrient parameters as a function of seasonal variation.

Netravathi-Gurupura河口是热带的，微潮至中潮的河口，位于印度西南海岸的芒格洛尔。河口通往阿拉伯海，被认为是印度主要的上升流系统之一。通过研究河流，河口和海洋组成部分的水化学和水生生物生理，我们的研究集中于内塔拉瓦蒂－古鲁普拉河口的季节性浮游植物演替。在季风季节，河口区普遍存在低氧条件（DO <3 mg L ^-1）。在2018年季风季节期间，河口和海域的盐度非常低，并且硅酸盐含量很高（> 100μmolL ^-1）促进了河口硅藻（Skeletonema costatum）等硅藻的繁殖和开花。在2018年季风季节期间，浮游植物组成与硅酸盐之间存在强烈的负相关性（r = -0.977）。TDS的大量夹带（> 10000 ppm），相对较高的盐度（33–35psμ）和高TN：TP（42.0–67.0μmolL ^-1）和鞭毛藻的增殖是非季风季节的特征。浮游植物与NO3（r = 0.989）和TN：TP（r = -0.997）显着正相关。就浮游植物的物种多样性而言，我们的研究将河口带划分为最少的带，特别是在2018年季风季节期间（D> 0.55，1 / D <1.82）。浮游植物从硅藻（季风）到鞭毛藻（非季风）的演替归因于理化和营养参数随季节变化的变化。