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RESEARCH PRODUCT

Effect of sublethal exposure to mercury in the biochemical composition of hepatopancreas in Procambarus clarkii during the recovery after starvation

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Abstract Freshwater crayfish undergo seasonal periods of starvation. The hepatopancreas is the main energetic-storage organ in this animal. An adequate replenishment of energetic reserves after these periods of fasting is critical for the proper growth and reproduction in this species. Mercury compounds enter the biological environment from natural discharges and anthropogenic sources. Mercuric chloride is one of the most toxic metallic salts found in polluted waters. In these studies, we report the effect of mercuric chloride in the biochemical composition of crayfish hepatopancreas during the recovery period after prolonged starvation. Adult intermolt crayfish (P. clarkii) were kept starved for 15 days, and a diet of pork liver ad libitum was then supplied. After feeding, animals were divided into two groups, one of them was exposed to 0·25 mg/litre HgCl2, and the second served as control. Total protein, total lipids, and glycogen concentrations were measured in hepatopancreas after 12, 48, and 96h of mercury exposure, and caloric concentrations were calculated. Whereas, in the control group, total lipids and caloric concentration increased with time after feeding, a decrease in the levels of these parameters was found in the mercury-exposed group. The differences between both groups were statistically significant after 96h of toxicant exposure. Thus, sublethal concentrations of mercuric chloride are able to inhibit the replenishment of energetic reserves in crayfish hepatopancreas after starvation. This could have adverse effects during molting or reproduction periods, when these reserves are dramatically needed.