Nutrient (N and P) Enrichment Coupled with Phytoplankton Dynamics of Mullaperiyar reservoir in the Western Ghats of Kerala

R. Jithesh Krishnan

Department of Botany, N.S.S College, Nilamel, Kollam, Kerala, India.

ABSTRACT: Periyar Lake, situated inside the Periyar Tiger Reserve (PTR) and Wildlife Sanctuary, a major international tourist centre in Kerala, was studied for a year (January to December 2005), in order to explore the nutrient status and associated phytoplankton growth. This oldest manmade freshwater reservoir/Lake in the Western Ghats of Kerala, is getting more attention now a days due to the dispute between Kerala State and Tamil Nadu (TN) State for the ownership of the Mullaperiyar Dam. More over it is situated inside India's prime Tiger reserve in its quantity, area and quality. Total Nitrogen and inorganic Phosphorus of the waters were studied every month and the data were grouped into three different seasons and analyzed the seasonal fluctuation if any, moreover, water samples from different parts of the entire Lake were also analyzed to account any spatial variation due the increasing anthropogenic influence in and around the Lake related with tourism. From the study it was revealed that Nitrogen and Phosphorus concentration of the Lake was at an alarming rate during premonsoon and northeast monsoon in stations-1 and 5 (2400 to 3000 ?g/L), with maximum human influence and sewage entry. While the inlets zones (station-4) showed minimum N and P contents (1500 ?g/L) . The density of Phytoplankton showed a positive correlation with the nutrients in almost all seasons. The highest plankton density( 490 no./L) was recorded during premonsoon at station-5 and the lowest was at station-4 (253 no./L) during northeast monsoon.From this study it was clear that the nutrient and phytoplankton of the Lake is dependent on the seasonal fluctuations in the environment as well influenced by the increased anthropogenic activities in and around the Lake. Strict measures should be taken to monitor the water quality of this pristine water body within the sanctuary because this is the source of drinking water for 4 Districts of TN.

KEYWORDS: Nutrients; Nitrogen; Phosphorus; tropical; high altitude; freshwater; Western Ghats

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