Acute and subchronic effects of petroleum on the freshwater fish Hoplias aff. malabaricus.

R M Santos,H O Souza,A R Soares,V L Sousa,A C Petry,A Azevedo,L I Weber

doi:10.1590/1519-6984.253731

Abstract

Petroleum water soluble fraction (WSF) impairs organisms, but damages may vary among cell and tissue levels. The aim of the present study was to evaluate the acute (24 h, 48 h, 72 h) and subchronic effects (36 days) of WSF (0%, 25% and 100%) in juveniles of the Neotropical top predator fish Hoplias aff. malabaricus. The effects of WSF were evaluated at a molecular level using the comet assay and micronucleus test for genome damage; and at a morphological level through histological identification of liver pathologic lesions. In both acute and subchronic exposure we found low levels of DNA damage (< 10% of comet tail) and non-significant frequency of micronucleus in WSF exposed fish. The most significant liver lesions in WSF exposed fish were fatty vacuolization, hypertrophy and focal necrosis. Since these tissue injuries were progressive and persistent, their irreversibility may negatively affect fish recruitment, even in a such resistant top predator.

Highlights

Brazil currently occupies the sixth position on crude oil production, which comprises approximately 5.5% of the world amount (Trading Economics, 2019)
The exposure of juveniles of H. aff. malabaricus to petroleum water soluble fraction (WSF) revealed in general low levels of DNA damage (< 10% tail DNA), but most comet measurements (CT, TL, %T, TM, OM) revealed significant differences between exposed and non-exposed individuals in both acute and subchronic tests (Figure 1)
Some significant changes were observed in WSF treated fish, such as fatty vacuolization (Figure 3B), nuclear degenerations, hypertrophy (Figure 3D) and necrosis (Figure 3F)

Summary

Introduction

Brazil currently occupies the sixth position on crude oil production, which comprises approximately 5.5% of the world amount (Trading Economics, 2019). Marine compartments are much more susceptible to contamination risks from offshore oil spills, hundreds of coastal waterbodies, such as shallow lagoons [that in Brazil are mostly concentrated along the southeast coast (Petry et al, 2016)] may be contaminated. Malabaricus (Bloch, 1794) occupies the top position of the food chains This species is widespread through almost all hydrographic basins of South America and exerts a keystone effect (Oyakawa, 2003; Petry et al, 2010; Silva et al, 2011). This sedentary and ambush fish since the juvenile stage has been used as a model in several experimental studies, which investigated the effects of temperature over growth and prey consumption (Petry et al, 2007); of pesticides over liver tissue (Miranda et al, 2008); of metals and pesticides over DNA (Cestari et al, 2004; Ferraro et al, 2004; Ramsdorf et al, 2009); and of petroleum over feeding and growth rates (Santos et al, 2016)

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