Sensitivity, ecotoxicity and histopathological effects on neotropical fish exposed to glyphosate alone and associated to surfactant

Abstract

The aim of this research was to evaluate neotropical fish sensitivity (Piaractus mesopotamicus, Phallocerus caudimaculatus, Hyphessobrycon eques, and Brachydanio rerio) to a reference substance (potassium chloride); to estimate the lethal concentration (LC 50 ; 96 h) for glyphosate, formulated as Rodeo ® alone and in association with 0.5 and 1.0% Aterbane ® BR surfactant and to evaluate the histopathology of the gills, liver, and kidney from the fish after acute exposure. P. caudimaculatus and H. eques are good bioindicators like B. rerio because they have similar sensitivity. The LC 50 ;96 h for glyphosate alone and in association with 0.5% Aterbane ® BR was similar (>975.0 mg L-1) for all the fish. Aterbane ® BR alone was the most toxic substance to P. caudimaculatus (5.81 mg L-1 LC 50 ;96 h) and glyphosate associated to 1.0% Aterbane ® BR was more toxic to H. eques (411.91 mg L-1 LC 50 ;96 h). The glyphosate alone and in association with Aterbane ® BR was classified as practically non-toxic, whereas Aterbane ® BR alone was considered moderately toxic for the tested organisms. The histopathological effects caused by glyphosate exposure on gills, liver, and kidneys are reversible, except for the liver necrosis on P. caudimaculatus. H. eques, P. caudimaculatus, and P. mesopotamicus present great potential to be used as standard organisms for herbicides monitoring and the use of glyphosate without surfactant addition is enough to cause histological alterations on H. eques and P. caudimaculatus, which makes them possible to be applied on environmental monitoring studies as biomarkers.

Chemical exposure hazardous for fish Hyphessobrycon eques through the incorrect release of oil in Amazon region

“…Different organisms can show different sensibility with toxicity tests until in several development stages [15,17,18] . According to Rodrigues [12] , they observed severe toxicity of brute oil, diesel and gasoline for lavae Odontesthes argentinensis which determined lethal dose 70.68, 13.46 e 5.48%, respectively, showing its toxic effect.…”

“…In this scenario with incorrect discard of burned oil and missing knowledge about the toxic effects, the use of toxicity tests to determine physiological changes or mortality it becomes too necessary for an adequate future management [15] . Among the native fish species, the Hyphessobrycon eques stands out as adequate biological model for acute toxicity tests due to their high sensibility [16,17] . Thus, this study aimed to determine the lethal dose (LD50%) of burned oil diluted in water using the biological model H. eques evaluating physiological responses with glucose values.…”