Effect of physico-chemical conditions on the structure and composition of the phytoplankton community in Wular Lake at Lankrishipora, Kashmir

The high altitude valley of Kashmir abounds in a vast array of freshwater bodies of lotic as well as lentic nature. Amongst these, lakes play an important role in biodiversity of this region. The present study on Wular Lake, Kashmir was undertaken from March, 2007 to February, 2008 to study abundance and distribution of phytoplankton and their correlation with physico-chemical conditions of water. A total of 64 phytoplankton belonging to bacillariophyceae, chlorophyceae, cyanophyceae and euglenophyceae were identified. Phytoplankton in general, showed two growth periods, one in spring and other in winter. A clear dominance of bacillariophyceae over chlorophyceae, cyanophyceae and euglenophyceae was observed throughout the study period. Navicula spp. with population density of 118 no./ml was recorded to be the most abundant species amongst bacillariophyceae at the selected site. Chlorophyceae formed the second most dominant group of phytoplankton with Chlorella spp. (112 no./ml) as the most abundant species. Osillatoria spp. with population density of 119 no./ml was found to be the most abundant amongst cyanophyceae. Euglenophyceae formed the least represented group of phytoplankton with peak population in spring. Statistically, bacillariophyceae and euglenophyceae showed significant negative correlation (r = -0.855 and r = -0.177) with water temperature, while cyanophyceae showed significant positive correlation (r = 0.745). Chlorophyceae showed non-significant positive correlation (r = 0.325) with water temperature at the selected site. Shannon-Wiener diversity index (H′) value (1.672) was recorded for cyanophyceae, while the highest evenness (J′) value (0.8872) was recorded for euglenophyceae. The value of Berger-Parker index of dominance (0.1859) was highest for bacillariophyceae. Canonical correspondance analysis (CCA) was also carried out to analyze the relationship between the physico-chemical parameters and the phytoplankton. It showed that the most important factors affecting phytoplankton distribution are water temperature, CO2, chloride, transparency, TDS, alkalinity and dissolved oxygen.   Key words: Biodiversity, freshwater bodies, phytoplankton, Wular Lake.