Will this be a possible effect of the Mitchell fire?
Bird eggs poisoned by toxins
The University of New South Wales
Friday, 16 September 2011
Toxic industrial pollutants contaminate bird eggs in Australia's
major eastern cities at levels seven to nine times higher than those in
inland areas, a new study has found.
The findings raise questions about potential impacts on bird breeding
success and about the accumulation of such toxins in their predators higher
up the food chain.
Researchers at the Australian Wetlands and Rivers Centre at UNSW
tested for pollution levels in eggs of Australian white ibis sampled in and
around Sydney, Newcastle, Brisbane and Melbourne and compared them with eggs
from the same species at four rural wetlands in NSW, Victoria and South
Australia.
The tests revealed widespread contamination from a range of
environmentally hazardous man-made pollutants - including DDT, dioxins and
PCBs - released as a result of the use of pesticides, flame retardants and
cooling agents and by industrial incineration.
"The good news is that pollutant levels found in Australian ibis eggs
are not as bad as in other parts of the world," says researcher Camila
Ridoutt, an Honours student in environmental science and author of the
study. On average, they were lower than levels from major urban cities such
as United States and China, although the difference varied from only 1 per
cent lower for dioxins to more than 100 per cent lower for PCBs.
"The bad news is that the levels were much higher in urban centres
compared with those detected at inland wetlands," says Ridoutt. "We also
found that the urban eggs were substantially smaller in size, weight and
volume compared to inland eggs. The pollutants may be contributing to this."
This could pose fertility problems for ibis and may have ramifications
for predators of ibis, says co-author Professor Richard Kingsford, who heads
the Centre.
"Small eggs can lead to lower reproductive success, which may be a
problem faced by our city ibis," says Professor Kingsford. "Given that
pollutants like these tend to bio-accumulate in the tissues of animals,
predators that eat the eggs or hunt ibis are also at risk." White-bellied
sea eagles that live in the Sydney area may be particularly affected, says
Ridoutt.
The study is one of the most comprehensive analyses attempted in
Australia on pollutants and their build up in bird eggs, says Professor
Kingsford. The researchers tested 219 eggs at 11 sites across eastern
Australia for organohalogenated pollutants, which can be highly toxic and
persistent in the environment and so have been prohibited since the 1980s.
They include polychlorinated dibenzofurans, polychlorinated biphenyls
(PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine
pesticides, such as DDT. The sites surveyed were four inland wetlands
(Watchels Lagoon, in South Australia; Mathoura, Lowbidgee and Macquarie
Marshes in NSW) and urban or near-urban areas in NSW - Sydney (the CBD,
Bankstown and Camden) and Newcastle; in Queensland (Brisbane); and in
Victoria (Mud Islands, near Melbourne, and Shepparton).
The most contaminated individual egg - with high levels of a
particularly toxic furan pollutant, 2,3,4,7,8-PeCDF - was found at Macquarie
Marshes, where there was a die-off in 1995 of chicks poisoned by the
pesticide chlorpyrifos. Professor Kingsford said such a finding in a wetland
of international significance warranted further investigation.
The researchers suggest the high pollutant levels found in urban eggs
reflect the birds' feeding habits and foraging places. In natural areas,
white ibis mainly eat small live prey - such as yabbies, frogs, crickets and
earthworms - but in cities they frequent landfills, waste dumps and
recreation areas and are known to ingest everything from picnic scraps to
paper and plastics.
Chemical analysis of eggs was conducted at the Dioxin Analysis Unit of
the National Measurement Institute.
http://www.sciencealert.com.au/news/20111509-22621.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencealert-latestnews+%28ScienceAlert-Latest+Stories%29
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