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Subject: Aquaculture × Author: LAXMI, B × Start date: 2018 ×
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    ThesisItemOpen Access
    Toxicity Bioassay of Organophosphorous Pesticide, Dichlorvos (DDVP) in Fingerlings of Cyprinus carpio (Linnaeus, 1758)
    (SRI VENKATESWARA VETERINARY UNIVERSITY, TIRUPATI - 517502, A.P. (INDIA), 2018-12) LAXMI, B; MADHAVI, K (MAJOR); DHANAPAL, K; CHAMUNDESWARI DEVI, B
    Toxicological effects of pesticides on aquatic organisms are very important, especially when these animals are serving as functional foods with respect to human consumption. Dichlorvos, one of the extensively used insecticides was investigated in the present study for acute and sublethal toxicity. Fingerling common carp (Cyprinus carpio) was selected for the bioassay experiments. Acute toxicity test through static bioassay was conducted by exposing common carp fingerlings to dichlorvos in the laboratory. The 96 hour LC50 value was found to be 21.11 ppm. Impact of test conditions (hardness of water) on LC50 value was evidenced in the present research, water hardness has resulted in decreased toxic potential of test substance, there by increased LC50 value compared to earlier works. The animals were experimented in pH: 7.1±0.2; Salinity: 1 ppt; Temperature: 32±2˚C; Alkalinity: 220±18 ppm; Hardness: 380±26 ppm; Dissolved oxygen: 8.0±0.6 ppm. For sublethal toxicity studies 1/5th & 1/10th LC50 concentrations were selected and were carried out following semi-static (static renewal) bioassay method for 28 days (4 weeks) to observe pesticide induced changes in physiological activities (feed consumption rate, ammonia excretion rate) and proximate composition (crude protein, crude fat, ash and moisture contents) of fingerling common carp. In sublethal toxicity studies, fishes seemed to be under stress with reduced metabolic performance, but were not fatal. Exposure to sublethal concentrations of dichlorvos resulted in dose (concentration) and duration dependent decrease in case of crude protein, crude fat, food consumption rate and increase in ash, moisture contents, ammonia excretion rate by the end of the test tenure. Food consumption and ammonia excretion rates though showed minor changes during the study period, by the end of exposure they equalized the initial values in case of control groups, whereas showed 1.17 fold decrease and 1.1 fold increase respectively in 1/5th LC50 compared to 1/10th LC50 concentration. The sublethal toxicity impact (either negative or positive) of ‘dichlorvos’ on biochemical (proximate) composition of fingerling common carp was in the order of crude fat > ash > moisture > crude protein. Though toxicant impact was seemed to be somewhat less on crude protein, the intensity of damage due to this on nutritive value of fish is more compared to its counter parts. The findings of present lethal and sublethal toxicity studies would be helpful in framing guidelines to protect aquatic animals against physiological death (i.e., mortality) and ecological death (i.e., unable to function in an ecological context, due to altered biological activities) respectively.