In all parts of the world pesticides have been found in the aquatic ecosystem and scientific evidence has also shown that they can enter the food chain. Diazinon is an organophosphate pesticide, widely used in agricul...In all parts of the world pesticides have been found in the aquatic ecosystem and scientific evidence has also shown that they can enter the food chain. Diazinon is an organophosphate pesticide, widely used in agriculture to control a wide variety of suckling and leaf eating insects and recently in fish culture to suppress some parasitic diseases;nevertheless, there is little study on its adverse effect on fish. In this study, seventy-two (72) apparently healthy catfish comprising adult and juvenile of both sexes were used to set up triplicate experimental groups of those exposed to culture water alone (control group), fish exposed to pre-determined no-effect concentration (0.405 ppm) of Diazinon (test group). The fish were exposed for 28 days and fish were sacrificed and organs harvested on days 21 and 28 to determine the effect of long-term exposure to diazinon on organ histology. Histological changes observed in diazinon-exposed catfish were hyperplasia and fusion of the gill epithelium, hyperplasia of mucoid producing cells and aggregation of melanin pigment in the skin. Histological lesions were also seen observed in other organs, including severe diffuse cellular swelling and fatty degeneration of the liver, interstitial congestion of the kidney, carbon deposit on the wall of the heart and multifocal haemorrhage. The water quality of the control was not significantly different from that of the test group throughout the experiment. The lesions detected in cells, tissue, or organs represent an integration of cumulative effects of physiological and biochemical stressors. The histological alterations observed in vital organ of fish show that exposure to “no-effect” concentration of diazinon induced structural damage in fish organs and are likely to affect the functionality of the organs. For example, the adverse effect on the gill might disrupt its feeding and oxygen uptake.展开更多
In most tropical developing countries, one of the problems facing aquaculture industry is the pollution of ponds and rivers with pesticides. Chemicals such as diazinon, an organophosphate pesticide, originating from a...In most tropical developing countries, one of the problems facing aquaculture industry is the pollution of ponds and rivers with pesticides. Chemicals such as diazinon, an organophosphate pesticide, originating from agricultural activity enter the aquatic environment through atmospheric deposition, surface run-off or leaching. Pollutants enter the food chain through accumulation in soft bottom sediment and aquatic organisms. However, information on how these pesticides affect inhabiting organisms is often not available. In a triplicate experimental set-up, seventy-two (72) apparently healthy catfish comprising adult and juvenile of both sexes were therefore exposed to a previously determined no effect concentration (0.405 ppm) of diazinon. Another set of fish was exposed to 0.0625 μg sodium arsenite, a known clastogen, which was used as the positive control, while another set of catfish exposed to the culture water alone was the negative control. Adults and juveniles were exposed separately to avoid cannibalism. After 48 hours of exposure, micronuclei induction was determined in subsets of experimental groups, while exposure continued for 28 days. Catfish organs were harvested on days 21 and 28 to determine the effect of long-term exposure to diazinon on histology. Water quality was also monitored before and during exposure in the experimental groups. The result established a significantly high mean micronucleated polychromatic erythrocytes (15.00) in catfish exposed to diazinon suggesting genetic damage (normal is ≤4). The MPE in sodium arsenite exposed fish was 28, while that of the control group was below 4. Effect of sex and age on micronuclei induction was not significant. Histological alteration observed in the ovary and testis was distorted matured cells and extensive testicular degeneration, respectively. The results show that diazinon has clastogenic effect, and may have endocrine disrupting properties because of the histological changes induced in the ovaries and testis.展开更多
Mortality is normal and natural in aquaculture experiments. However, it becomes a problem when measuring feed intake as a component of nutrient utilization parameters such as： feed conversion ratio, feed conversion e...Mortality is normal and natural in aquaculture experiments. However, it becomes a problem when measuring feed intake as a component of nutrient utilization parameters such as： feed conversion ratio, feed conversion efficiency, apparent net protein utilization, protein efficiency ratio and protein productive value. In order to accurately evaluate feed intake with due consideration of mortality encountered, a formulae was developed using empirical data obtained from an experiement that had mortality. The formulae Fwas： total feed consumed by numbers of survived fishes=DL∑i=1n（Fi/Ni）N. Where, D=Numbers of days fishes were fed within each period ibefore it was adjusted（e.g fortnight）, it was constant throught period of experiment; F=Uantity of feed fed per day for a fortnight before the quantity was adjusted, it changed every fortnight; L=Numbers of living fishes at the end of experimental period; N=Numbers of fishes at each weighing period, it might change every fortnight or might be constant if no mortality occurred; while n=Numbers of times fishes were weighed and quantity of feed was adjusted but this did not include the final weighing at the termination of experiment. However, if the fishes were weighed weekly, then D=6.展开更多
文摘In all parts of the world pesticides have been found in the aquatic ecosystem and scientific evidence has also shown that they can enter the food chain. Diazinon is an organophosphate pesticide, widely used in agriculture to control a wide variety of suckling and leaf eating insects and recently in fish culture to suppress some parasitic diseases;nevertheless, there is little study on its adverse effect on fish. In this study, seventy-two (72) apparently healthy catfish comprising adult and juvenile of both sexes were used to set up triplicate experimental groups of those exposed to culture water alone (control group), fish exposed to pre-determined no-effect concentration (0.405 ppm) of Diazinon (test group). The fish were exposed for 28 days and fish were sacrificed and organs harvested on days 21 and 28 to determine the effect of long-term exposure to diazinon on organ histology. Histological changes observed in diazinon-exposed catfish were hyperplasia and fusion of the gill epithelium, hyperplasia of mucoid producing cells and aggregation of melanin pigment in the skin. Histological lesions were also seen observed in other organs, including severe diffuse cellular swelling and fatty degeneration of the liver, interstitial congestion of the kidney, carbon deposit on the wall of the heart and multifocal haemorrhage. The water quality of the control was not significantly different from that of the test group throughout the experiment. The lesions detected in cells, tissue, or organs represent an integration of cumulative effects of physiological and biochemical stressors. The histological alterations observed in vital organ of fish show that exposure to “no-effect” concentration of diazinon induced structural damage in fish organs and are likely to affect the functionality of the organs. For example, the adverse effect on the gill might disrupt its feeding and oxygen uptake.
文摘In most tropical developing countries, one of the problems facing aquaculture industry is the pollution of ponds and rivers with pesticides. Chemicals such as diazinon, an organophosphate pesticide, originating from agricultural activity enter the aquatic environment through atmospheric deposition, surface run-off or leaching. Pollutants enter the food chain through accumulation in soft bottom sediment and aquatic organisms. However, information on how these pesticides affect inhabiting organisms is often not available. In a triplicate experimental set-up, seventy-two (72) apparently healthy catfish comprising adult and juvenile of both sexes were therefore exposed to a previously determined no effect concentration (0.405 ppm) of diazinon. Another set of fish was exposed to 0.0625 μg sodium arsenite, a known clastogen, which was used as the positive control, while another set of catfish exposed to the culture water alone was the negative control. Adults and juveniles were exposed separately to avoid cannibalism. After 48 hours of exposure, micronuclei induction was determined in subsets of experimental groups, while exposure continued for 28 days. Catfish organs were harvested on days 21 and 28 to determine the effect of long-term exposure to diazinon on histology. Water quality was also monitored before and during exposure in the experimental groups. The result established a significantly high mean micronucleated polychromatic erythrocytes (15.00) in catfish exposed to diazinon suggesting genetic damage (normal is ≤4). The MPE in sodium arsenite exposed fish was 28, while that of the control group was below 4. Effect of sex and age on micronuclei induction was not significant. Histological alteration observed in the ovary and testis was distorted matured cells and extensive testicular degeneration, respectively. The results show that diazinon has clastogenic effect, and may have endocrine disrupting properties because of the histological changes induced in the ovaries and testis.
文摘Mortality is normal and natural in aquaculture experiments. However, it becomes a problem when measuring feed intake as a component of nutrient utilization parameters such as： feed conversion ratio, feed conversion efficiency, apparent net protein utilization, protein efficiency ratio and protein productive value. In order to accurately evaluate feed intake with due consideration of mortality encountered, a formulae was developed using empirical data obtained from an experiement that had mortality. The formulae Fwas： total feed consumed by numbers of survived fishes=DL∑i=1n（Fi/Ni）N. Where, D=Numbers of days fishes were fed within each period ibefore it was adjusted（e.g fortnight）, it was constant throught period of experiment; F=Uantity of feed fed per day for a fortnight before the quantity was adjusted, it changed every fortnight; L=Numbers of living fishes at the end of experimental period; N=Numbers of fishes at each weighing period, it might change every fortnight or might be constant if no mortality occurred; while n=Numbers of times fishes were weighed and quantity of feed was adjusted but this did not include the final weighing at the termination of experiment. However, if the fishes were weighed weekly, then D=6.
