RESUMEN
The anthropogenic pressure in recent years has driven us to investigate the environmental quality at 22 stations in Parangipettai by collecting seawater samples monthly from 2014 to 2015. The sampling stations were grouped into three different environments, namely, Vellar Estuary (VE), Coleroon Estuary (CE), and Open Sea (OS). Factor analysis showed a total variance of 65.63% and exhibited a strong factor loading for atmospheric temperature (0.914), water temperature (0.917), ammonia (0.767), inorganic phosphate (0.897), total phosphorus (0.783), and phytoplankton (0.829). The index value showed water quality was good in OS (74.18), whereas it was moderate in VE (69.73) and CE (68.47). The visual model developed using Geographical Information System (GIS) displayed a spatial pattern of water temperature and phytoplankton dispersion in a distinct manner. The results obtained through multivariate analysis and GIS-based model are imperative to establish reference for a comparative study with other similar ecosystem for better planning and management of tropical seawaters.