Variations in biomarkers at different biological levels in the wild fish species Arius subrostratus (Vallenciennes, 1840) from a polyaromatic hydrocarbon (PAH) contaminated estuary in India

The present study investigated the variations in biomarkers of polyaromatic hydrocarbons (PAH) in wild fish Arius subrostratus from the Cochin estuary. Growth indices, hematological parameters, antioxidants, histopathology, and apoptosis-related gene expressions were analyzed and compared to the PAH quantified from bile. Biliary PAH in fishes from the middle estuarine area was the highest followed by the lower and upper estuarine areas (sampling sites grouped based on their position, hydrodynamics, and possible source of PAH). As the biliary PAH increased, the condition factor decreased, whereas the hepato-somatic index increased. Hematology showed signs of macrocytic anemia with decreased RBC and hematocrit. However, antioxidant enzymes were found to be an unsuitable biomarker of PAH exposure in wild fishes. The major histological observations in the liver were hepatocellular nuclear polymorphism, fibrosis, and vacuolization. The expression of GST, Bax, Cytochrome C, CYP1A1, and p53 were upregulated in fishes from the most contaminated sites. The significant alterations in the growth indices, hematology, histopathology, and apoptosis-related gene expression of A. subrostratus with the change in biliary PAH suggest that it can be used as a species for monitoring PAH. The study further observed the complexities of using biomarkers for monitoring PAH contamination and impact assessment in estuaries.