Histopathological analysis of tilapia gills ( Oreochromis niloticus Linnaeus, 1758 ) exposed to sugarcane vinasse

Abstract

Sugarcane vinasse is one of the main residues generated by the transformation of cane into ethanol. Because of the high organic content (COD), high biochemical oxygen demand (BOD), low pH, the large amount that this residue is generated (15l for every liter of ethanol produced) and their use as fertilizer on the sugarcane crop, this residue is potentially polluting to the soil ecossystem and by percolation to water ecossystem too. Thus, this study aimed to assess the toxicity of vinasse by analyzing Oreochromis niloticus gills exposed to different dilutions (1%, 2.5%, 5% and 10%) in two bioassays. The gills were collected, fixed and analyzed using ultra morphological, histological, and histochemical techniques. After exposure to the vinasse, a statistically significant reduction of the ridges present on the surface of pavimentous cells was observed in one of the bioassays; such structures are responsible for mucus retention, which helps to protect the tissue. In addition, an intumescence of the cells was observed in the treatments with vinasse as well as an increase in the amount of chloridric cells. Some striking tissue changes detected in the treatments were epithelial detachment and loss of integrity of secondary lamellae, causing their rupture and consequent hemorrhage. In the first bioassay, the amount of these changes was statistically significant at the 5% dilution, and the focus of hemorrhage was significant at all dilution ratios. In the second bioassay, the epithelial disorganization was statistically significant only at the 2.5% dilution of vinasse. Moreover, for both bioassays performed, a significant increase in mucous cells was observed when compared with the control. Our results demonstrate the toxic action of sugarcane vinasse, which caused histopathological changes in the exposed animals at all four dilution tested. This highlights the need for caution in the disposal of sugarcane vinasse on the soil, especially due to its capacity for being leached or percolated into water resources, which could seriously damage aquatic fauna.

Ecotoxicidade de efluentes para organismos aquáticos

“…Assim como em outros tipos de efluentes, os bioensaios ecotoxicológicos O estudo desenvolvido por Correia et al (2017) avaliou a toxicidade da vinhaça analisando as brânquias de tilápias (Oreochromis niloticus) expostas a diluições (1%, 2,5%, 5% e 10%) em bioensaios. Por meio da análise das brânquias, observou-se uma redução dos sulcos presentes na superfície das células pavimentadas.…”

“…Além disso, observou-se uma intumescência das células nos tratamentos com vinhaça, bem como um aumento na quantidade de células clorídricas. Foi observada alterações nos tecidos como descolamento epitelial e perda de integridade das lamelas secundárias, causando sua ruptura e consequente hemorragia (CORREIA et al, 2017).…”

“…Com isso, Correia et al (2017), concluiu que a vinhaça apresenta potencial tóxico e citotóxico em ambientes aquáticos. Esta afirmação é baseada nas altas taxas de mortalidade observadas nas diluições mais altas, nas alterações morfológicas no tecido branquial e também pelo aumento significativo de células mucosas para todas as diluições de vinhaça testadas.…”

Effects of insecticides on aquatic ecosystems in Bangladesh

“…To address this knowledge gap, we aimed at assessing the effects of long-term exposure to chlorpyrifos on the mortality and reproductive tissues of adult Banded Gourami using the mortality, gonado-somatic index (GSI) and histopathological observations. We studied the histopathological alterations of Banded Gourami after chronic exposure to chlorpyrifos, because histopathological examination represents a useful and rapid tool to assess the degree of pollution, particularly for sub-lethal and chronic effects in various tissues and organs (Cengiz and Unlu, 2006;Velmurugan et al, 2007;Chourpagar and Kulkarani, 2014;Paruruckumani et al, 2015;Correia et al, 2017). The results of the study would elucidate the dose-and duration-dependent mortality and reproductive damages of Banded Gourami fish due to toxic effects of chlorpyrifos.…”

“…Among vertebrates, fish is often used as suitable bio-indicator, because of their wide distribution in aquatic environment, long lifespan, free swimming, ability to respond against environmental xenobiotics, and importance as a food source for human beings (Gupta et al, 2009;Narra et al, 2011;Correia et al, 2017).…”