The use of pesticides and fertilizers is generating ecological risk to aquatic
ecosystems depending on availability of different xenobiotics for biota and the
environment, exposing the aquatic and human populations to toxic substances
through drinking water and animals contaminated. Confusion Lagoon region, for
decades has been an important area for agribusiness and the lack monitoring of
contaminants derived from this activity can compromise the quality of the aquatic
ecosystem. This study aimed to evaluate the ecological risk by xenobiotics, using
the Peacock Bass (Cichla sp.) as bioindicator for evaluation of possible xenobiotic
effects associated with agricultural activities in the city of Confusion Lagoon - TO.
Water and fish samples were carried out from September 2013 to October 2014
in three points (A - River Javaés/Pium, B - Javaés river/Confusion Lagoon and C
- Formoso River/Confusion Lagoon). To evaluate the water quality was used
physicochemical parameters and concentration of heavy metals (Cd, Pb, Cu, Cr,
Mn, Ni and Zn). To assess the ecological risk of bioindicator was used to
determine the concentration of metals (Cd, Pb, Cu, Cr, Mn, Ni and Zn) in the liver
and muscle, and the following biomarkers: genotoxic (micronucleus test) and
biochemical (serum glucose, AST and ALT) and histological (liver and gills).
Regarding the physical and chemical parameters, the total phosphorus at point
C showed above the reference value. There was no significant difference in
concentration of metals in the water among the three sampling sites (p> 0.05) at
point A. The average of Cu, Cr and Mn in the three points collected exceeded the
values for Class 1 rivers, according to Conama Resolution 357, indicating
contamination of water resources for these metals. Only Cr was above the
maximum allowed for human consumption, but was not significantly different at
point A (p> 0.05). The micronucleus test revealed a low frequency in the three
collection sites. Hyperglycemia was observed in the animals of point C. In the
gills, the most frequent changes were epithelial lifting, hyperplasia and
hypertrophy of the lamellar epithelium, congestion, partial lamellar fusion and
total, edema, inflammatory infiltration, capillary dilatation and less frequently
aneurysm and focal necrosis. In the liver, the most common histopathological
changes were stage I and II, as cytoplasmic vacuolization, nuclear hypertrophy,
dilation of sinusoids, derangement of hepatic cords, bile stagnation, congestion
of vessels, inflammatory infiltrate and pyknotic nuclei. It was also observed the
occurrence of focal necrosis. Integrated assessment of the concentration of
metals in water and tissues of fish and biomarkers indicates contamination both
water and fish by metal, probably from agricultural activities, requiring the
monitoring of the quality of the aquatic ecosystem in the region, as tucunarés
beyond its ecological role, also part of the food for the local population.
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