Use of Biomarkers in Crab (Callinectes sapidus, Rathbun 1896) as Pollution Indicators in a Niger Delta Creek

Background and Objective: Hydrocarbon extraction activities along the coastlines of the Niger Delta are rife for decades and have contributed to various categories of persistent pollutants in the aquatic ecosystem. The bioaccumulation and induction of some biochemical markers in the blue crab, Callinectes sapidus as indicators of chronic petrogenic pollutions was studied. Materials and Methods: In situ, measurements for water temperature, pH, electrical conductivity, salinity, total dissolved solids and dissolved oxygen were made at the sampling locations. Forty-eight female crabs (weight 149.2±0.02 g) were harvested with a 15 mm mesh size fishing net and taken to the laboratory in plastic containers filled with their habitat water for the estimation of biomarker levels. Results: Tissue accumulations of the Polynuclear Aromatic Hydrocarbons (PAHs) at OSD ranged from 0.02-0.09 μg g^–1 and Mononuclear Aromatic Hydrocarbons (MAHs) from 0.01-0.02 μg g^–1, but were 0.01 μg g^–1 and undetected in tissues at ISD. The levels of Alanine Aminotransferase (ALT) (sig. = 0.032), Aspartate Aminotransferase (AST) (sig. = 0.045), Alkaline Phosphatase (ALP) (sig. = 0.007), total proteins (sig. = 0.036) and malondialdehyde (MDA) (sig. = 0.005) were all markedly higher at the OSD location at the 95% confidence limit. The ordination biplot revealed that the explained variations for axes 1 and 2 were 68.95 and 85.38% and the eigenvalues were 0.689 and 0.164, respectively. The multivariate pie classes showed that the largest sector for AST was OSD 2, MDA and ALT were OSD 1 and ALP was OSD 3. Elevated PAHs and MAHs appeared to induce the production of more ALP (r = 0.695 and 0.660, respectively, p<0.05) and PAHs alone induced the production of more proteins (r = 0.630 and p<0.05). Conclusion: It was confirmed that allocthonous input of petroleum pollutants in aquatic ecosystems could cause biological disruptions, including tissue bioaccumulation and other biochemical disruptions in proteins and enzyme activities.