Abstract
The present study was designed to investigate acute toxicity of dimethoate on juvenile Cyprinus carpio var. communis. Fishes weighing 10 ± 2 gms were selected and mortality data was statistically evaluated by Finney's Probit Method. The 96-hour LC50 value for Cyprinus carpio was found as 1.1 ppm in static bioassay system. Mean values of physicochemical parameters of aquarium waters determined during bioassay depicted slight variation indicating that the mortality in aquarium fishes occurred due to pesticide exposure and not suffocation. Lab. temperature ranged from 12 to 13°C; water temperature ranged from 11 to 12°C; dissolved oxygen ranged from 3.90 to 4.56 mg/L; pH ranged from 6.90 to 7.05; total dissolved solids ranged from 2.66 to 3.0 × 103 mg/L, while CO2 remained at a constant value of 2.0 mg/L. The fishes elicited various behavioural responses such as uncoordinated movements, convulsions, excessive mucus secretion, and imbalanced swimming which ended in a collapse to the bottom of the aquarium. Prior to death, the clinical signs like scale erosion, pale body colour, and hemorrhagic patches over the body were noticed which became more vivid up to the termination of experiments. Results of the study indicate potential toxicity of dimethoate in fingerlings of common carp for which the natural waterbodies must be continuously monitored to reduce its impact across food chains.
Highlights
Jammu and Kashmir is an agricultural state with varied agroclimatic conditions suitable for the cultivation of different types of crops
A total number of 360 specimens of Cyprinus carpio var. communis were brought from hatchery of Faculty of Fisheries, SKUAST-K, to the laboratory in plastic bags with adequate water, avoiding any physical injury to them
The median lethal concentration (LC50) values in the present study were determined on the basis of range finding tests done thrice as replicates (r1, r2, and r3) (Table 1)
Summary
Jammu and Kashmir is an agricultural state with varied agroclimatic conditions suitable for the cultivation of different types of crops. Kashmir province of the state is well recognized by horticulture, where apple cultivation finds the primary importance. The fruit production of Kashmir province alone is 1.5 million metric tons annually from a total orchard area of 0.2 million hectares, which is sprayed and fogged with 7750 metric tons of fungicides and 3186 metric tons of insecticides, right from March to November every year [1]. The use of pesticides leaves a negative impact on the nontarget species, especially in the aquatic environments. Nonjudicious and unavoidable entrance of pesticides into natural waterbodies through leaching, percolation, precipitation, drift, or runoff leads to contamination of natural water resources and to toxicity to aquatic organisms. Once uptaken through any of the routes, these xenobiotics are potent to cause physiological dysfunctions like oxidative stress [4,5,6] and haematological [7,8,9,10] and biochemical [9, 11] changes in fishes
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