Respostas metabólicas do tambaqui (Colossoma macropomum) de cativeiro exposto à concentrações subletais de paration-metílica

Abstract

The tambaqui (Colossoma macropomum) is to main fish species cultivated in the Amazonia Western. However several such chemical products as herbicides, algicides, larvicides, fungicides and veterinary drugs have been introduced intentionally in the hydric atmospheres. Among the pesticides commonly used in the local pisciculture for the control of ectoparasites and aquatic insects, they stand out the parathion methyl (Mentox® 600 CE). The present study was verified if the tambaqui (Colossoma macropomum) when exposed to conditions sublethal of the organophosphates parathion methyl (PM) UNDERGOES metabolic alterations. Inside of that intention, toxicological tests were accomplished for the determination of the lethal concentration (CL50%). the toxicity of the parathion methyl represented lesser than 2 mg/L (CL50-96h of 1,456 mg/L and 2,317 mg/L). Therefore, after the determination of the lethal concentration, specimens of juveniles tambaqui, were separate in groups of 10 animals in boxes of 390 L: a group control maintained without the presence of the organophosphates and other four groups were exposed to 0; 0,5; 0,70; 0,98; 1,37 and 1,92 of parathion methyl/L of water for 96 hours. All the groups had your feeding suspended 24 hours before initiate the experiment. The following parameters were analyzed: hemoglobin content, hematocrit, erythocyte, VCM, HCM, CHCM, concentrations glucose plasmatic, ammonia, sodium, chloride and potassium, above the hepatic activity of the enzyme glutathione-S-transpherase (GST). The exposed individuals the these conditions presented decrease in the natatorial and erratic activity, excessive production of mucus and expansion of the inferior lip were observed. The results of the effect of the exhibition to concentrations below 2 mg/L of the commercial formulation of MP (Mentox® 600 CE) they allowed to establish that the alterations of the parameters hematologic happened starting from the first treatment in relation to the group it controls, yet they put not enough to mitigate the stress answers, because there was no significant difference in the sanguine variables and nor in the indexes hematimetrics. Typical answers to the stress were not detected due to the handling imposed the fish during the accomplishment of the exhibition of the Colossoma macropomum them sublethals concentrations of the parathion methyl, elucidated through the alterations of the concentrations glucose plasmatic, ammonia and íons (Na+, Cl-, K+), they put the exhibition to the parathion methyl it caused increase of the glutathione activity S-transpherase (GST) starting from the treatment 0.70 mg/L.