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Abstract
Study of the exposure effect of insecticide profenofos (selecron) on physiological responses of Nile tilapia, Oreochromis niloticus
The pesticide of interest here is the organophosphorus insecticide (profenofos) which is used for controlling of insects, mites on cotton, maize, sugar beat, soybeans, potatoes, vegetables and other crops. So, profenofos is widely distributed in aquatic habitat due to their wide use in in agriculture, the aquatic habitat with its water quality is considered the main factor controlling the state of health and disease of fish.
The effect of profenofos as organophosphorus insecticide on the Nile tilapia, Oreochromis niloticus as a result of acute exposure (1/2 LC50) to 0.435 mg profenofos/l and chronic exposure (1/10 LC50) to 0.087 mg profenofos/l and also left the treated fish for 28 days and left for another 28 days after withdrawal the insecticide as recovery period. For that purpose the 96 hrs LC50 of Nile tilapia, Oreochromis niloticus was determined to be 0.87mg /l as exposed to profenofos. Then, the fresh blood, serum and some organs (muscles, gills and liver) were taken to investigate some hematological, biochemical changes, some serum and liver enzymes activity and insecticide residues in water aquaria and investigated organs in Nile tilapia. Data representing in the following:
1. Hematological parameters in Nile tilapia:
Blood parameters:
There were a highly significant increase in WBCs counts during both the acute and chronic exposure to profenofos. Also, WBCs count increased during the recovery period. On the other hand, there were a highly significant decrease in RBCs counts, Hb content and Hct % during both trail periods. These results showed enhancement during recovery period.
Blood indices:
The results showed a significant increase in MCHC during both acute and chronic periods and also, data showed enhancement for returning to control one. On the other hand, MCH and MCV showed a highly significant decreases in tilapia during acute period.While, MCH showed a highly significant increase during chronic and recovery period. Concerning the MCV value showed a highly significant decrease at the end of chronic period. During the recovery period, data showed a significant increase in MCV as compared with control one.
2. Influence of acute and chronic exposure of profenofos on some metabolities and enzymes of serum and liver in Nile tilapia:
• The results showed a highly significant increase in level of blood glucose after acute and chronic exposure to profenofos and also throughout the recovery period.
• The results revealed a significant decrease in liver and muscles glycogen throughout the trail periods and also during the recovery period.
• It also observed a highly significant decrease in serum total protein and globulin during acute exposure period. Also, during the chronic period, serum total protein recorded a highly significant decrease during the first 14 days and then the effect was reversed at the end of trail period. Furthermore, the results revealed a sharp significant increase in albumin and A/G ratio after acute and chronic periods. All data were nearly return to normal one within recovery period.
• Also, data recorded a sharp elevation in serum creatinine, urea and uric acid in treated profenofos tilapia during both the acute, chronic and recovery periods.
• Also, the results revealed a significant decrease in serum total lipid, triglyceride and cholesterol during acute period in tilapia. Also, Nile tilapia recorded a highly significant decrease in serum total lipid, triglyceride and cholesterol during the first 7 days within chronic period and then the effect was reversed with sharp elevation for the end of trail period. Tilapia try to return to the control one during recovery.
• The results revealed a sharp elevation in the activity of serum enzymes, S-AST, S-ALT and S-ALP during acute, chronic and recovery periods in exposed tilapia except S-ALP return to the normal one during recovery period. The results also revealed a significant increase in the activities of liver transaminases (L-AST & L-ALT) throughout the whole experiment and recovery period.
3. Bioaccumulation of profenofos in water aquaria and tissues of Nile tilapia, Oreochromis niloticus:
No detectable profenofos residues in control water aquaria, muscles, gills and liver of the Nile tilapia, Oreochromis niloticus.
The obtained data indicated that, the amount of profenofos was gradually decreased in water quaria throughout the experimental course. It not detectable in water after 14. 21 and 28 days of trail period and during recovery.
Concerning profenofos residues in fish organs (muscles, gills and liver), profenofos residues were accumulated during the acute exposure and increased gradually through 1 to 7 days within chronic period followed by gradual decreasing at the remained periods till the residues not detectable at the end of 28 days and during recovery period for another 28 days. The residues of profenofos were much higher in liver than the other investigated organs as follow: (liver < gills < muscles).
CONCLUSION
from the previous investigations and this results, we could be summarized some main factors accounted for the decline of fisheries as follow:
1. The drainage water discharges into lakes and River Nile containing large amounts of pollutants such as pesticides, the prescence of such pollutants have deleterious effect on the aquatic biota including fish. Furthermore, bioaccumulation of pesticides in fish tissues to a level that affects their physiological status.
2. On the other hand, exposure of fish to a mixture of pesticide residues may cause risks exceeding those induced from exposure to residues of a single pesticide.
This mixture of pollutants may be effects on fish reproductive, retardation of development and physiological status of fish.
RECOMMENDATIONS:
It is necessary to solve the problem of pollution and decline of fisheries in lakes, River Nile and fish farms. Some suggestions may be recommended as follow:
1. Doing national project by Ministry of Agriculture aimed to solve the problem of pollution, from our results and previous studies, for development of fisheries and doing permissible limits of pollutants in irrigation and drainage water.
2. Remediation of agricultural wastewater drainage before discharge into the lakes and River Nile by building of remedation stations on main drains.
3. Preventing industrial and human discharges into Lakes and River Nile before remediation.