What is in the water that great white sharks swim in? #Scibraai Monday Menu

A great white shark. Photo: Wikimedia

A great white shark. Photo: Wikimedia

Skin samples of great white sharks contain worrying levels of environmental and biological contaminants. This is among the findings of a recent study in the journal Expert Opinion on Environmental Biology. Skin biopsies were taken from 15 great white sharks near Dyer Island off the Overberg coastline. The Italian and South African researchers involved ascribe the high percentages of DDT and its metabolites found to the recent introduction of this chemical to fight malaria in the KwaZulu-Natal region.

The study was conducted by researchers from among others the Universities of Siena and Calabria in Italy, as well as from Stellenbosch University.

Compared to other top marine animals, very high levels of potentially carcinogenic polycyclic aromatic hydrocarbons (PAHs) were found in these sharks. Oil and tar are among others made up of these. PAHs were evaluated in white sharks because South Africa is on one of the most frequented oil shipping routes, and 28% of the Middle East oil passes along our coastline. This class of organic molecules can be toxic and can cause cancer in exposed organisms.

Male sharks had about 70% of environmental oestrogens and anti-androgens in the muscle. Many laboratories and several field studies clearly show that exposure to oestrogens is also consistent with effects in female fish. The researchers also believe that a mainly industrial contaminant is probably the source of polychlorinated biphenyl (PCBs) found.

The study was the first to use skin biopsies to evaluate the eco-toxicological status of free-ranging great white sharks. This non-lethal and non-harmful technique permits a large number of scientific investigations.

Citation: Marsili L, Coppola D, Giannetti M, Casini S, Fossi MC, et al. (2016) Skin Biopsies as a Sensitive Non-Lethal Technique for the Ecotoxicological Studies of Great White Shark (Carcharodon carcharias) Sampled in South Africa. Expert Opinion on Environmental Biology4:1 doi:10.4172/2325-9655.1000126


Engela Duvenage

Co-founder of SciBraai.co.za. Day job: Science writer and science communicator who loves turning research papers into news stories. Claim to fame: mother of two daughters; winner of the Izethelo Award for Outstanding Journalism (2016) from the South African fruit industry, and winner of the best technical article award (2016) as presented by the South African Agricultural Writers' Association Background: MPhil (Journalism, specialising in science journalism) and HonsBA (Psychology).

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