Metal concentrations in the Helderberg Marine Protected Area, False Bay, Cape Town

Abstract

The release of metals is increasing in industrial and urban areas and the impacts thereof are poorly understood. In an attempt to protect areas from anthropogenic impacts, certain areas are declared protected. The assumption thus could be that protected areas are free from the effects of pollutants. The Helderberg Marine Protected Area (HMPA) is situated in an urbanised region of False Bay, Cape Town, South Africa. Although considered a protected area, the question is raised whether metals from the surrounding area are affecting the coastal environment of the MPA. Materials and Methods: The study assessed the concentrations of 8 metals (Al, Mn, As, Mo, Cd, Fe, Cu and Zn) in the water, sediment and mussel Mytilus galloprovincialis. Samples were collected from within the HMPA, at its border (Lourens river) and adjacent to the HMPA (Strand) in August, 2012. Results: The results showed that metal concentrations were higher in the sediment than ambient coastal waters. Furthermore, metal concentrations were higher in mussels than the sediment for As, Mo, Cd, Cu and Fe. Conclusion: The most important result was that mussel Al, Mn, Cd, Cu and Fe concentrations were similar in and adjacent to the HMPA. The results suggested that the environment of the HMPA was exposed to contaminants (such as metals sampled in this study) from areas outside the MPA and management authorities should consider the effects of these and other contaminants in management plans of MPAʼs.