Changes in selected biochemical parameters in the kidney and blood of the fish,Tilapia mossambica (Peters), exposed to heptachlor

Bulletin of Environmental Contamination and Toxicology -     

Toxicity of selected organic pesticides to a fresh water teleost fish,Saccobranchus fossilis and its application in controlling water pollution

Bioassay studies have been conducted with chlordane (an organochlorine compound), and Ekatin?, Ekalaux?, and Sumithion? (organophosphorous compounds) to determine the LC₅₀, acute toxicities, relative toxicities, presumable harmless concentrations, and dilution volumes for a period of 24-, 48-, 72-, and 96-hr to a fresh water teleostSaccobranchus fossilis. The 24-, 48-, 72-, and 96-hr LC₅₀ for chlordane, Ekalaux, Ekatin, and Sumithion are 0.54, 0.49, 0.46, and 0.42 mg/L; 2.75, 2.40, 1.75, and 1.55 mg/L; 12.40, 12.10, 11.75, and 11.00 mg/L; and 14.90, 14.20, 13.75, and 12.50 mg/L, respectively. Presumable harmless concentrations are 0.12, 0.55, 3.46, and 3.87 mg/L, respectively, which are a fraction of LC₅₀ values. The relative toxicities of these pesticides calculated on the basis of 24-hr LC₅₀ to the fish are 27.59, 5.42, 1.20, and 1.00 for chlordane, Ekalaux, Ekatin, and Sumithion, respectively. The acute toxicity for Sumithion to the test fish lies between 12.10 and 18.75 mg/L, for chlordane between 0.37 and 0.75 mg/L, for Ekatin between 10.00 and 14.20 mg/L, and for Ekalaux between 1.35 and 3.25 mg/L. It is concluded from the study that chlordane is the most toxic and Sumithion is the least toxic while the toxicities of Ekatin and Ekalaux lie between the two. When the data for survival of the test fishvs. log concentration are plotted, they exhibit a linear relationship following the formula Y= ˉY+b(X−ˉX). The presumable harmless concentrations can be utilized on broad lines for controlling short-term water pollution by these pesticides.     

Biochemical changes in the liver of fish, Tilapia mossambica (Peters), during continuous exposure to monocrotophos

The purpose of the present investigation was to determine the effect of continuous exposure to the organophosphate monocrotophos at 2.5 ppm for over a period of 2 through 45 days on protein, RNA, and DNA contents and on 5'-nucleotidase activity in the liver of Tilapia mossambica. Protein content was decreased by 45% after 5 days, returned to control levels at 10-30 days, and again decreased by 45 days. DNA content was decreased by 2 days, returned to control values by 5 days, and remained constant throughout the exposure. In contrast, RNA content was significantly lower starting from 2 through 45 days of exposure. 5'-Nucleotidase activity showed a transient increase at 5 and 30 days of monocrotophos exposure. These results indicate that monocrotophos altered the protein, DNA, and RNA contents and the 5'-nucleotidase activity levels as early as 2 and 5 days. However, these changes were reversed by 10 days and after a short period of recovery, the alterations reappeared. This supports our earlier histological observations of hepatic pathology during monocrotophos exposure.     

Fluoride-induced changes in carbohydrate metabolism in the tissues of fresh water crab Barytelphusa querini

Exposure of fresh water crab Barytelphusa querini to a sublethal concentration of NaF (30 ppm) caused significant alterations in the carbohydrate metabolism. In an exposure span of 15 days the crab was observed to have marked depletion in glycogen and total free sugar levels. A significant elevation in "active" and "total" glycogen phosphorylase activity was observed. The activity changes of lactate dehydrogenase reflected changes in tissue lactate levels and succinate dehydrogenase activity had a tissue specificity.     

Acute, sublethal exposure to a pyrethroid insecticide alters behavior, growth, and predation risk in larvae of the fathead minnow (Pimephales promelas)

The present study determined the effects of environmentally relevant, short-term (4-h) exposure to the pyrethroid insecticide esfenvalerate on mortality, food consumption, growth, swimming ability, and predation risk in larvae of the fathead minnow (Pimephales promelas). Acute effect concentrations were determined, and in subsequent experiments, fish were exposed to the following measured sublethal concentrations: 0.072, 0.455, and 1.142 microg/L of esfenvalerate. To measure growth rates (% dry wt/d), 8-d-old fathead minnows were exposed to esfenvalerate for 4 h, then transferred to control water and held for 7 d. Food consumption and abnormal swimming behavior were recorded daily. Additional behavioral experiments were conducted to evaluate how esfenvalerate affects the optomotor response of the fish. To quantify predation risk, esfenvalerate-exposed fathead minnow larvae were transferred to 9.5-L aquaria, each containing one juvenile threespine stickleback (Gasterosteus aculeatus). Sticklebacks were allowed to feed for 45 min, after which the number of surviving minnows was recorded. No mortality occurred during 4-h exposures to esfenvalerate, even at nominal concentrations of greater than 20 microg/L. Delayed mortality (50%) was observed at 2 microg/L after an additional 20 h in clean water. Fish exposed to 0.455 and 1.142 microg/L of esfenvalerate exhibited impaired swimming and feeding ability as well as reduced growth compared to fish exposed to 0.072 microg/L and controls. Predation risk also was significantly increased for larvae exposed to 0.455 and 1.142 microg/L of esfenvalerate. These results demonstrate that larval fish experiencing acute exposures to sublethal concentrations of this insecticide exhibit significant behavioral impairment, leading to reduced growth and increased susceptibility to predation, with potentially severe consequences for their ecological fitness.     

Regulation of phosphorylases and aldolases in tissues of the teleost (Tilapia mossambica) under methyl parathion impact

Bulletin of Environmental Contamination and Toxicology -     

Toxicity,bioconcentration, and metabolism of the herbicide propanil (3′,4′-dichloropropionanilide) in freshwater fish

Fathead minnows (Pimephales promelas) were exposed to technical grade propanil (3′,4′-dichloropropionanilide) in a flow-through diluter system to determine acute lethality. LC₅₀ values were 11.5, 10.2, 8.6, and 3.4 mg·L^?1 at 24, 48, 96, and 192 hr, respectively. Eggs, newly hatched fry, and juvenile fish of this species were similarly exposed but at lower concentrations and for a period of 58 days. The 58-day “no effect” concentration was between 0.4 and 0.6Μg·L^?1, based upon the physiological parameters of length and dry weight of juvenile fish.¹⁴C-Propanil did not bioconcentrate significantly in fathead minnows (1.6× for parent propanil in whole body). Rainbow trout (Salmo gairdneri) readily metabolized propanil, forming at least ten products. One metabolite recovered from trout bile was identified as either 3′,4′-dichloro-2-hydroxypropionanilide or 3′,4′-dichloro-3-hydroxy-propionanilide. The technical grade propanil also contained 0.67 mg·g^?1 of 3,3′,4,4′-tetrachloroazobenzene as a contaminant.