|Little penguins on Penguin Island, |
near Perth. Photo by John Lindie.
Some rights reserved.
Penguins are a key indicator species of marine health because they eat a variety of fish. By analysing feather samples from adult and juvenile birds, the three-year study found that penguins on Penguin Island, 40km from Perth, had 1.7 milligrams of mercury per kilogram of feathers, compared to 0.6mg/kg in penguins on Woody Island, where mercury pollution is minimal.
"Our results show that the Perth site is contaminated with three times more mercury, mainly because you've got a lot more potential sources for mercury in the metropolitan area," lead researcher Nic Dunlop told The Sunday Times.
Penguins from a third colony on Mistaken Island near Albany were also tested and found to have mercury levels of 1.3mg/kg. This relatively high reading has been blamed on a phosphate plant in Albany that dumped waste into the harbour for almost 30 years.
Although the mercury level found in Perth's marine life was signficantly higher than elsewhere, Professor Dunlop said, "In our more industrialised areas, as far as we can tell, consuming fish is safe at the moment."
He added, however, that the oceans were Earth's biggest "mercury sink" and "it was going to get more and more difficult to get healthy seafood because the background levels of mercury are increasing quite rapidly".
High mercury levels in Perth waters spark seafood concerns by Trevor Paddenburg, 19 February 2011, The Sunday Times