Efecto de glifosato sobre la salud de la tilapia roja (oreochromis sp.) en su etapa juvenil.

Abstract

One of the most popular herbicides is glyphosate in the agricultural sector, and due to uncontrolled discharges of this product, often influenced by precipitation or the use of sprinklers for irrigation, residues of this herbicide often end up in rivers or water bodies. These water sources are later used for the cultivation of aquatic organisms. The present study aimed to assess the effect of glyphosate on the health of juvenile tilapia (Oreochromis sp.) over a 42-day period, to determine the impact of the herbicide on this fish species since this herbicide is a toxic substance that can endanger the health of these animals. For the experimental setup, sublethal concentrations of 25 mg/L and 50 mg/L were established, along with a control treatment that did not contain glyphosate (0 mg/L). Twenty-seven juvenile red tilapia with an average weight of 50 g (Oreochromis sp.) were used and were fed twice a day based on their biomass. The organisms were evenly distributed in containers, with three fish per tank for each treatment. To control water parameters and sustain the glyphosate concentration in the experimental units, 100% water exchange was conducted every 2 days. Measurements of weight (g) and length (cm) were taken weekly to evaluate growth. The analyzed blood parameter was red blood cell count (RBC). Survival was determined by assessing the final number of live animals at the end of the experiment. The findings of this study demonstrated that exposure to glyphosate at sublethal doses of 25 mg/L and 50 mg/L for 42 days was toxic to juvenile red tilapia. Regarding growth, significant differences (p < 0.05) were observed between the treatments, with the best growth recorded in the control (0 mg/L), while the lowest weekly growth average was recorded at 50 mg/L. Concerning the blood parameter, it was shown that there were no significant differences (p > 0.05) between the sublethal glyphosate doses, but both differed statistically from the control, which had a higher mean number of RBCs than the herbicide-exposed treatments. Additionally, the survival rate remained stable during the first 5 weeks; however, a decline was observed in the 50 mg/L treatment in the 6th week, resulting in the lowest survival rate compared to the other treatments at the end of the experiment. The findings of this study demonstrated that glyphosate at doses of 25 mg/L and 50 mg/L negatively affects the health of red tilapia. Therefore, it is recommended to conduct future experiments with concentrations < 25 mg/L to determine the threshold beyond which glyphosate should not be allowed in aquaculture production facilities.