Crescimento e parâmetros toxicológicos em jundiás (Rhamdia quelen) expostos a uma formulação comercial do herbicida 2,4-D

Abstract

In this study, silver catfish (Rhamdia quelen) were exposed to commercial formulation to 2,4-D herbicide at 0.0 (control) 0.5 or 2.0 mg L-1 for 90 days or 96 hours. After the exposure were evaluated the growth, mucous layer composition, metabolic parameters, TBARS formation in different tissues and liver catalase activity. R. quelen showed reduction on some growth parameter as final mean mass that decrease on 37% and 46% respectively to 0.5 or 2.0 mg L-1, total body length to 15 % to high concentration tested. Daily mass gain reduced to 55% and 58% to both concentrations tested. The specific growth decrease of 1.20 (control) to 0.72 and 0.60 respectively to both concentrations tested. The factor of condition reduced 22% and 12% for 0.5 or 2.0 mg L-1 2,4-D concentration. The silver catfish showed alterations on mucous layer contents as decrease of soluble sugar at both concentrations tested and increase of protein levels at 2.0 mg L-1 to herbicide concentration after 90 days and 96 hours of exposure. Fish exposed to 2,4-D herbicide at 0.5 or 2.0 mg L-1 presented glycogen reduction and protein level in the liver tissue after 90 days of exposure. But this tissue showed increase in lactate and glucose levels at both concentrations tested. The liver tissue of R. quelen after 96 h of exposure showed increased to glycogen level and reduced to lactate and protein levels to both concentrations tested, but were not significantly difference to glucose values. The muscle tissue after 90 days of exposure to 2,4-D showed reduced to glycogen and protein values at high concentration tested and decreases to glucose at both 2,4-D concentrations. Lactate levels were increased to 0.5 or 2.0 mg L-1 to 2,4-D herbicide. After 96 h of exposure this tissue presented reduced to glycogen and lactate levels, but the glucose and protein values was not altered as compared to control values. The kidney tissue showed decrease to glycogen and glucose values, but lactate was increased at both concentrations of 2,4-D and protein levels were not altered as compared to control values. This tissue after 96 h of exposure to 0.5 or 2.0 mg L-1 of herbicide showed decrease to lactate levels, but glycogen, glucose and protein values was not altered. The plasm metabolites presented reduction of lactate and protein levels at both concentrations tested. Glucose was not altered after 90 days of exposure. After 96 h the plasm showed reduction in lactate level, but glucose and protein was not significantly alteration as compared to control values. Catalase activity showed enhanced to both experimentation and both concentrations, values as compared to control. TBARS formation after 90 days to 2,4-D exposure showed decrease to liver tissue, but enhanced in white muscle. TBARS in brain tissue was not altered in this experimentation. After 96 h of 2,4-D exposure TBARS levels enhanced to liver tissue and was not alteration in the brain and white muscle tissue as compared to control values. Data demonstrated that 2,4-D herbicide alter the some growth parameters after long time exposure. Besides, this herbicide causes alterations on metabolic parameter and oxidative stress after 90 days and 96 hours of exposure.