Assessment of water quality in Shitalakhya river insights from phytoplankton and nutrient regimes

Abstract

The present study assessed the water quality parameter insights from phytoplankton and nutrient
regimes of the Shitalakhya River based on three sampling stations. The ranges of water temperature,
transparency, dissolved oxygen, pH, TDS, phosphate-phosphorus, nitrite-nitrogen, nitrate-nitrogen, and
silicate were 27.86±0.249 °C to 29.83±0.612 °C, 42.33±0.471 to 31.33±0.942 cm, 6.35±0.232 to
5.88±0.066 mg/L, 7.62±0.008 to 7.52±0.018, 63.33±4.714 to 40±8.164 mg/L, 0.52±0.020 to
0.34±0.016 mg/L, 0.06±0.012 to 0.01±0.004 mg/L, 0.12±0.008 to 0.05±0.004 mg/L, and 0.12±0.004
to 0.07±0.001 mg/L respectively. The values of transparency, TDS, nitrite, nitrate, and silicate varied
significantly while other parameters showed non-significant (p>0.05) among three stations. The results also
indicated the presence of 27 genera belonging to five major groups- Bacillariophyceae (9), Chlorophyceae
(8), Euglenophyceae (5), Dinophyceae (3), and Cyanophyceae (2). The dominant phytoplankton group was
the Bacillariophyceae (38%), followed in order by Chlorophyceae (26%), Euglenophyceae (19%),
Dinophyceae (12%), and Cyanophyceae (5%). Shannon-Weiner species diversity index (H?) ranged from 2.31
to 2.99 (phytoplankton) indicating the water body is moderately polluted. Overall, maximum density
(46.66×103 cells L-1) of phytoplankton was observed at S2 followed by S3 (35.23×103 cells L-1) and S1
(20.95×103 cells L-1). The fluctuation of the physico-chemical parameters and phytoplankton density of the
river could be attributed to the high influx of nutrients into the river as a result of discharging nutrient reach
water from. Monitoring of these activities within the river and education on the wise use of the water is
recommended.