Dynamics of heavy metals in seawater, sediment, mudprawns and fish tissues caught of Durban basin in South Africa: impacts and implications

Abstract

Durban Basin is highly prone to anthropogenic contamination, particularly heavy metals (HM). This is a critical environmental concern having a ramification on declining fish populace and quality of seafood prompting public health apprehensions in the region. However, there is no data in the literature on HM levels in the edible fish species, including the potential health risk of consumers. Therefore, this study aimed at determining baseline levels of HM accumulation in popular edible fishes and the potential public health risk that may be associated with their consumption. Further, the study assessed the trophic level transfer and the suitability of the studied fish species as bio-indicators that could be used for the systematic and periodic monitoring of toxic metal pollution in the marine environment. Results indicated that anthropic HM levels in fish species in the Durban basin exhibited both spatial and interspecific variability with Durban South and Harbour reporting higher values than other sites. Studied fish species also had higher mean levels of lead (Pb) beyond maximum allowable limit levels of 0.5 mg/kg prescribed by the South African Department of Health (DOH). Among edible fishes, Slinger had significantly (p<0.05) high accumulation patterns of arsenic (As), chromium (Cr), Nickel (Ni) and Pb exceeding the permitted regulatory levels in seafood. Intraspecific regional differences in HM levels in both maasbanker and slinger from the pristine (Cape Vidal) and polluted (Durban basin) marine environments were observed, indicating that the two species are potentially suitable for heavy metal pollution biomonitoring. Risk assessment revealed that all fish species had THQ>1 for Cr, implying a significant potential non carcinogenic health risk in the consumption of fish caught in the Durban