Phytoplankton dynamics and seasonal variation in Tungabhadra River, India

Tungabhadra River, an important tributary of Krishna, flows in the district Davangere in the central part of Karnataka State, India. A total of 64 species of phytoplankton were recorded during the present study period. These include 23 species of Chlorophyceae, 18 species of Cyanophyceae, 14 species of Bacillariophyceae and 9 species of Euglenophyceae. Water and algal samples were collected at regular intervals of 15 days at 2 stations from December 2006 to October 2007. The results of the summer (December-March), winter (April-July) and rainy (August-November) seasons indicate that the highest phytoplankton dynamics were represented by 39 species in the summer season. In this study, green algae constituted the highest percentage of 35.29 and 36.67% followed by blue green algae (29.41 and 26.67%), Diatoms (23.53 and 20.00%) and Euglenphyceae (11.76 and 16.67%) at Stations 1 and 2 respectively. Maximum and minimum densities of 21,476 and 16,682 o/L were recorded at Station S1 while those at Station S2 were 18,392 and 12,729 o/L respectively. The diversity of species varied from 0.160 to 1.147 during the study period. Phytoplankton species richness ranged from 0.371 to 0.552 while the phytoplankton species evenness varied from 0.079 to 0.671 during the study period.    Key words: Phytoplankton dynamics, algae species, river, statistical analysis, India.