Evaluation of Physicochemical Characteristics of Coastal Waters of Nellore, Southeast Coast of India, by a Multivariate Statistical Approach

Krupa Ratnam,M Prashanthi Devi,Dilip Kumar Jha,Gopal Dharani

doi:10.3389/fmars.2022.857957

Abstract

The Swarnamukhi river estuary (SRE), and the surrounding sea in Nellore, southeast coast of India, is one of the least studied marine environments, notably for physicochemical characteristics. Seawater samples were collected from five stations every month from 2014 to 2017 to assess physicochemical characteristics. The open sea (OS) station was significantly different from the inner stations, according to non-metric multidimensional scaling and cluster analysis. The variability was shown by strong factor loadings of atmospheric temperature (0.87), water temperature (0.84), biochemical oxygen demand (0.77), ammonia (0.85), and total nitrogen (0.78). Furthermore, one-way ANOVA and box-whisker plots facilitated simplifying and corroborating multivariate results that showed high concentration in the inner stations. Based on the N/P and Si/N ratios, nitrate and silicate were the key limiting factors in this study. The findings are critical for establishing reference conditions for comparison studies with other comparable ecosystems in the tropical region for better environmental conservation and management.

Highlights

The coastal ecosystems harbor a rich diversity of marine flora and fauna because of their higher productivity (Saravanan et al, 2013)
Temperature plays a vital role in regulating the productivity in the coastal region, it was insignificant at the spatial scale (p > 0.05) for water temperature (WT) (20.4–33.6◦C) and atmospheric temperature (AT) (24.0–39.3◦C) but significant (p < 0.05) at the temporal scale
A low pH value was recorded in the inner stations of the Swarnamukhi river estuary (SRE) (SR2 and Buckingham Canal (BC)), which could be attributed to effluent discharge from the surrounding environments

Summary

Introduction

The coastal ecosystems harbor a rich diversity of marine flora and fauna because of their higher productivity (Saravanan et al, 2013). These ecosystems are the most precious and vulnerable environments (Jickells, 1998). A growing number of seawater quality monitoring programs to collect huge datasets are crucial for a better understanding of how anthropogenic activities affect the coastal environments (Jha et al, 2015). A few environmental contamination studies have been carried out on metal pollution (foraminifera, seawater, sediment, bivalves, and benthos) in this area (Sundara Raja Reddy et al, 2016; Patel et al, 2018; Jha et al, 2019; Pandey et al, 2021), long-term studies on the physicochemical parameters are sparse (Sreenivasulu et al, 2016)

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