Assessment of Oxidative Stress and Histopathological Biomarkers in the Parablennius Incognitus Fish as Potential Contamination Indicators of the Bay of Sousse (Tunisia)

Oxidative stress and histopathological biomarkers were investigated in the gills and liver of Parablennius incognitus fishes. Individuals sampled in the bay of Sousse were compared to fishes from a reference site, i.e. Ghdamsi Island (Tunisia). Severe biochemical and histological alterations were observed in fishes from Sousse bay and associated with urban discharges contamination. Several tissue alterations were also observed in gills, particularly lamellar epithelium detachment, disorganization of pillar cells, and hypertrophy of chloride cells. In the liver we noted particularly hypertrophy of hepatocytes, congestion and dilation of the central vein and sinusoid capillaries, pyknotic nucleus, and hepatic steatosis. The high reduction of superoxide dismutase and catalase activities in gills and of superoxide dismutase and glutathione peroxidase activities in the liver of contaminated fishes may explain the increase of lipoperoxidation in both organs of P. incognitus. The integrated biomarker response values found in individuals from the contaminated site were in good agreement with alteration of physico-chemical parameters and with the high level of Cd concentrations detected in water of the stressful place, i.e. the bay of Sousse. Oxidative stress and histopathological alterations were sensitive biomarkers to discriminate between fishes from the polluted Sousse bay site and those from the reference site, suggesting their potential utility in bio monitoring.