Studies on Morphometry, Water Quality and Phytoplankton Diversity of Nilnag Lake, Kashmir
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Date
2022
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SKUAST Kashmir
Abstract
The present research was aimed to study the morphometry, water quality, and phytoplankton diversity of Nilnag Lake, a small pine forest rural freshwater lake situated between Lat: 33°51'23''N, Long: 74°41'42''E, about 50 km south of Srinagar city in District Budgam, at an altitude of 2110 m asl. The study was carried out for a stipulated time period of 6 months, covering spring and summer seasons. The bathymetric map and morphometric study revealed that the lake circumscribes surface area (S) of 8.16 Ha, with maximum length (l) and maximum breadth (b) of 595 m and 219 m respectively, with mean breadth (¯b) of 137.1 m. The lake recorded maximum depth (Zm) of 6.4 m, mean depth (¯(z )) of 4.4 m, mean depth to maximum depth ratio (¯(z )/zm) of 0.68 and relative depth (Zr) of 1.98 %. Shoreline length (L) of 1587 m, shoreline development (DL) of 1.56, volume (V) of 359.284 × 103m3 and volume development (DV) of 2.06 was also recorded during the current study. The hypsographic curve of the lake highlighted that the (D50), (D75), and (D25) values of the lake were 5.1 m, 4.1 m, and 5.6 m respectively. The depth-volume curve of the lake showed that 50% of the lake volume is approximately above 2.4 m depth. The minimum, maximum and average values of various physiochemical parameters recorded during the study period included; Air temperature of 10.8 °C, 30.4 °C and 21.04±1.04 °C, Water temperature 11 °C, 26.5 °C and 19.2±1.05°C, Depth 4.3 m, 6.4 m and 5.14±0.12 m, Transparency 0.9 m, 1.6 m and 1.31±0.03 m, pH 7.1, 7.9 and 7.53±0.04, Specific Conductivity 196.3 µS/cm, 334.7 µS/cm and 256.26±6.96 µS/cm, Dissolved oxygen 4.2 mg/L, 11.6 mg/L and 6.43±0.31 mg/L, Carbon-di-oxide 2 mg/L, 46 mg/L and 15.4±2.16 mg/L, Ammonia 15.2 µg/L, 37.8 µg/L and 25.47±1.09 µg/L, Ortho-Phosphate 13 µg/L, 44.1 µg/L and 26.31±1.53 µg/L and Total Phosphorous 120.3 µg/L, 191.1 µg/L and 151.66±3.85 µg/L. A total of 101 phytoplankton species belonging to 5 classes were identified during the present study. Out of them, 49 species belonged to class Bacillariophyceae comprising 48.5%, 29 species belonged to class Chlorophyceae comprising 28.7%, 14 species belonged to class Cyanophyceae comprising 13.9%, 7 species belonged to class Euglenophyceae comprising 6.9% and 2 species belonged to class Dinophyceae comprising 2% of the total plankton population. The order of dominance in terms of both diversity and density observed was in the order of: Bacillariophyceae > Chlorophyceae > Cyanophyceae > Euglenophyceae > Dinophyceae. The study revealed that Nilnag lake has undergone a considerable change in its morphometric features which has also brought a concomitant change in its physio-chemical and biological characteristics
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Keywords
Bathymetric map, Volume, Water quality change, Phytoplankton species.