Spatial and seasonal variations in coastal water characteristics at Kalpakkam, western Bay of Bengal, Southeast India: a multivariate statistical approach

A study was carried out in the coastal waters of Kalpakkam with the objectives to evaluate the seasonality in hydrobiological parameters in surface and bottom waters, and assess the anthropogenic stress and monsoonal flux on a spatiotemporal scale. The study covered an area of approximately 100 km 2 in the coastal environment. Relatively high values for pH, temperature, and TP were observed during the post-monsoon (POM) season. The monsoon (MON) season was linked with TN, ammonia, and DO concentrations as all these parameters have shown increased values during this season due to freshwater input. The summer (SUM) season was characterized by salinity, turbidity, nitrate, phosphate, and silicate, indicating a true marine environmental condition for plankton production. Principal component analysis (PCA) and cluster analysis (CA) indicated the presence of distinct coastal water masses with respect to seasons and sampling regions. The spatial pattern indicated the distinctness of the coastal nearshore water (CNW) and coastal offshore water (COW) with respect to water quality. The CNW was more dynamic due to direct external influence as compared to the relatively stable COW environment. Similarly, the study region in the northern part, which is continuously exposed to the backwater inputs and tourism activities, was statistically different from the southern part.