Browsing by Author "Firth, Deborah Caitlin"
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- ItemTemporal and inter-species variations in the proximate and contaminant compositions of farmed mussels, Choromytilus meridionalis and Mytilus galloprovincialis, from Saldanha Bay, South Africa(Stellenbosch : Stellenbosch University, 2018-03) Firth, Deborah Caitlin; Hoffman, Louwrens C.; O’Neill, Bernadette; Salie, Khalid; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.ENGLISH ABSTRACT: Seafood is known to be a healthy source of protein, minerals and omega-3 fatty acids, but trace metal and persistent organic pollution in the ocean can threaten the health of seafood consumers through the bioaccumulation of contaminants in the marine food chain. Mussel aquaculture in Saldanha Bay creates essential local employment and provides ~1600 tonnes of seafood per annum for local consumption and export, but is threatened by the expansion of heavy industry, shipping traffic and a growing human population. Research into the impact of marine pollution in aquaculture is necessary to protect farmers and consumers, and to establish baseline data for future pollution studies. To assess temporal and inter-specific variations in the proximate and contaminant compositions of the farmed mussels from Saldanha Bay, native Choromytilus meridionalis and invasive Mytilus galloprovincialis, samples were collected from commercial mussel rafts at the centre of Small Bay at two-month intervals over two-years. Mussels were analysed for differences in morphometry, whole weights, meat weights, percentage meat yields, moisture, protein, fat, ash, trace metals (determined via ICP-MS) and a range of persistent organic pollutants (determined via GC-MS/MS), including organochlorine pesticides, polyaromatic hydrocarbons and polychlorinated biphenyls (PCBs). Significant temporal variations in whole weight, meat weight, percentage meat yield, proximate composition and contaminant compositions (Fe & As in C. meridionalis, Fe, As, Hg & Pb in M. galloprovincialis, and cis-permethrin, trans-permethrin, PCB 118 & PCB 149 in both species) were linked to changes brought on by the gametogenic cycle and storm water runoff during the winter rainfall period. Morphometrically, M. galloprovincialis was found to have a longer, wider and more ventrally flattened shell than C. meridionalis, and both species had similar moisture, protein, fat and ash contents. Species-related differences were observed for Al, Cr, Fe, Zn, Cd, Pb and PCBs 118 and 149 (higher in M. galloprovincialis), and Cu and Mn (higher in C. meridionalis). While concentrations of all persistent organic pollutants within the mussels were determined to be well below international regulatory limits, As concentrations exceeded the South African maximum limit (3mg/kg wet weight) once in each species, and Pb concentrations in M. galloprovincialis exceeded local regulations for fish (0.5mg/kg w.w.) on more than one occasion, but did not exceed EU regulatory limits for bivalves (1.5mg/kg w.w.). Overall, both farmed mussel species from Saldanha Bay were determined to be healthy sources of protein and essential trace metals for consumers, with the added benefit of low fat contents. Apart from As and Pb, the samples were relatively uncontaminated with trace metals or persistent organic pollutants and likely do not pose a significant human health risk. Additional research into pollution sources in Saldanha Bay and bivalve-specific contaminant regulations are suggested to support the future growth of the aquaculture industry in South Africa. The information from this study will be useful to farmers and consumers, and as baseline data for future research.