O. SUDHAKAR, P. NEELA RANI , G. VENUGOPAL AND J. P. GEORGE
Abstract
The present study was conducted in freshwater lake, Powai Lake, Mumbai. Concentrations of nutrients namely nitrites, nitrates, phosphates and silicates were recorded. The mean nitrite nitrogen concentration was found to be 0.0289 (±0.0121) mg/L. The mean Nitrate nitrogen concentration was recorded as 0.344 (± 0.098) mg/L. Total nitrogen was observed to be 0.373 (± 0.108) mg/L. Mean phosphate concentration was found to be 0.407 (± 0.105) mg/L. Mean silicate value was found out to be 25.97 (± 2.17) mg/L. N:P was found to be 0.915 (± 0.120) mg/L in the entire study period. The nutrient levels indicate that the lake is eutrophic. Various trophic algal indices namely (i) the myxophycean index; (ii) the chlorophycean index; (iii) the diatom index; (iv) euglenophyte index and (v) the compound index and algal species diversity indices like (i) Shannon-Weiner index and (ii) Simpson index were calculated. The myxophycean index was found to be 3; the chlorophycean was observed to be 2; the diatom index was found to be 0.25 while the euglenophyte index was 0.2 and the compound index was found to be 3.5. Shannon- Weiner Index was found to be 3.348 (± 0.0126) and Simpson diversity index was observed to be 0.877 (± 0.00717). The results show that the lake is eutriphic.