Spatial Trends of Metal Bioaccumulation in Penaeus monodon from Sediments in Degema, Nigeria

Abstract

Aims: This study investigated the spatial bioaccumulation of toxic metals (Cd, Pb, Cr, As, Zn, Cu, Ni) in the Giant Tiger Prawn (Penaeus monodon). Place and Duration of Study: The study was conducted at Bille Creek, Degema LGA, over six months, from December 2024 to May 2025. Methodology: Monthly samples of prawns and sediments were collected and analyzed for metal concentrations using Atomic Absorption Spectrophotometry (AAS). A total of 12 sediment and prawn samples were taken from three stations. The analysis also included Pearson correlation and bioaccumulation factor (BAF) calculations to determine the relationship between metal concentrations in sediment and prawn tissues. Results: The toxic metal concentrations in Penaeus monodon tissues followed a consistent order: Zn > Cu > Pb > Ni > Cr > Cd > As. Spatially, metal concentrations were homogeneous across stations (p > 0.05), indicating uniform contamination despite proximity to oil facilities. Zn, Pb, and Cd showed significant peaks during the early wet season, with the highest concentrations observed in December. Arsenic exhibited the highest Bioaccumulation Factor (BAF) of 1.222 in April, indicating its high bioavailability. Pearson correlation analysis revealed strong positive correlations (r > 0.90) between Cd, Pb, Cr, As, and Zn, suggesting shared anthropogenic sources, likely linked to oil activities. Cu demonstrated distinct bioaccumulation behaviour with negative correlations to other metals. Conclusion: This study concludes that P. monodon bioaccumulates metals across the creek, with seasonal variation in contamination levels. These findings highlight the need for targeted pollution control measures and seasonal consumption advisories to mitigate potential public health risks.