Physico-chemical characteristics and phytoplankton diversity of three  Stations viz., open sea, mangrove and freshwater zone of Muthukuda  region of Palk Bay, southeast coast of India for the period of two years from January 2012 to December 2013 were analyzed. The seasonal results showed high concentration all nutrients (phosphate, nitrate, nitrite, ammonia and silicate) at Station 3 (freshwater zone). Similarly, high Chl a, hytoplankton density and species richness values were noticed at open sea (Station 1), high species diversity values were observed at Station 2 (mangrove) while high species evenness were found at Station 1. Rotation mode varimax factor analyses were applied separately to open sea (Station 1), mangrove (Station 2) and freshwater zone (Station 3) data sets due to existing stratification in the water column caused by river water inflow. This helped us to understand the interrelationships between the variables and to identify the probable source components to explain the environmental status of the area. Four factors (each for Station1 and Station 3) and five factors (Station 2) were found responsible for variance (79.7% in Station 1, 80% in Station 2 and 77.6% in Station 3) in the Palk Strait  coastal waters of Muthukuda region.

Physico-chemical characteristics, Muthukuda mangrove environment, phytoplankton, diversity, rotation mode factor analysis.