Studies on Hydrobiological Characteristics and Ichthyofaunal Diversity of the Kulik River in Uttar Dinajpur District of West Bengal India

Abstract

The present study was done to analyse different physico-chemical parameters, ichthyofauna diversity newlineand plankton diversity of the river Kulik at the Raiganj and Hemtabad block in Uttar Dinajpur district newlineof West Bengal for two years from November 2019 to October 2021. The investigation was carried out newlinemonthly basis from the five selected sampling sites of the river Kulik. Air temperature ranged between newline12.80°C to 33.25°C during the whole study period. During the whole study period the water temperature newlineranged from 12.70°C to 32.10°C at all the sites. pH varied from 5.90 to 7.86 which indicates the slightly newlineacidic to slightly alkaline nature of the water. Electrical conductivity values were higher in the summer newlinemonths. At site 5 the dissolved oxygen value was recorded as lowest (1.60 mgL-1) during winter season newlineof the first-year. Excessive use of fertilizer at agricultural fields present near the river Kulik might be newlinethe reason of lowering of dissolved oxygen at that site. The sudden increase in dissolved oxygen newlineconcentrations at all the sites from March, 2020 to June, 2020 might be due to the lesser anthropogenic newlineactivities during the lockdown in India because of the Covid-19 Pandemic situation. Free CO2 showed newlinea positive correlation with chloride and BOD during the entire study period. Total alkalinity values newline(12.00 mgL-1 to 52.00 mgL-1) were ideal for fish growth and had a significant positive correlation with newlineBOD. Total hardness varies between 34.00 mgL-1 to 107.00 mgL-1 and had a significant negative newlinecorrelation with BOD at Site 3. Chloride (7.00 mgL-1 to 18.02 mgL-1) had a significant positive newlinecorrelation with BOD at Site 4 and Site 5. BOD values varied between 1.44 mgL-1 and 7.68 mg L-1. The newlinehighest BOD was recorded in April, 2020 at Site 5, which crossed the limits of CPCB standard set for newlinedrinking and bathing. From the present investigation, a total of 89 fish species belonging to 9 orders and newline27 families were recorded during the whole study period. The order Cypriniformes was found to be newlinedominant