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Scientists assess flood impact to Moreton Bay -

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While the massive clean-up is well underway in Queensland, the full environmental impact of the
floods in Moreton Bay, off Brisbane, is still being assessed.


TRACY BOWDEN, PRESENTER: While the massive clean-up is well underway in Queensland, the full
environmental impact of the floods is still being assessed.

The enormous amount of water that flowed down the Brisbane River two weeks ago brought with it
thousands of tonnes of silt, which is now settling in Moreton Bay, and that silt is laced with all
the pollutants of agricultural and urban development.

Scientists are now trying to determine how this will affect the Moreton Bay Marine Park and its
vulnerable populations of dugongs and sea turtles.

Peter McCutcheon reports.

PETER MCCUTCHEON, REPORTER: The floodwaters may have receded, but Brisbane's Moreton Bay is still
in shock. Environmental scientist Andrew Moss knows there's trouble lurking beneath the surface.
He's not sure exactly how much trouble, but he's trying to find out.

ANDREW MOSS, PRINCIPAL SCIENTIST, QLD ENVIRONMENT DEPT: Well, the data obviously suggests there's a
lot of dirt out in the bay, we're starting to see little starts of algal growth in the bay.

PETER MCCUTCHEON: That algal bloom is expected to peak in coming weeks, turning the water here a
distinctive green, but that's only part of the problem, with a potentially toxic cocktail of silt
and pollutants flowing into the Moreton Bay Marine Park.

MILES YEATES, MARINE PARK MANAGER: Yeah, it's definitely going to have an impact on the park, and
it's been 37 years since the last major flood, so it's a very rare event.

PETER MCCUTCHEON: Early last week, the plume of silt coming out of the Brisbane River was clearly

ANDREW MOSS: Obviously there's been a huge mass of fresh water and silt and various contaminants
come in to the bay, so we'll be looking at the effects of those over the next few weeks, because
they don't all happen straight away.

PETER MCCUTCHEON: The silt has mostly travelled to the northern and western part of the bay, but
some of this has shifted south and east to the bay's more environmentally sensitive areas. Where
the silt eventually ends up depends on tidal movements and the wind direction over the next few

BILL DENNISON, UNI. OF MARYLAND: That sediment that's now in Moreton Bay is laced with the
toxicants and the fertiliser that should be on the crops, growing the crops in the Lockyer, and now
it's a pollutant because it's a problem.

PETER MCCUTCHEON: Professor Bill Dennison is a former Brisbane resident and international expert on
sea grasses who has written several books on Moreton Bay. He says the plume of silt poses a threat
to sea grasses that are the main source of food for the bay's turtles and dugongs.

BILL DENNISON: Moreton Bay is really globally unique. It's the only place on the planet where you
can be in a healthy dugong turtle population and see a major city skyline.

PETER MCCUTCHEON: Park rangers are looking under the surface of the bay with the help of underwater
cameras to document exactly how the silt is affecting sensitive sea grasses. This is where the top
soil from the devastated Lockyer Valley is ending up: a murky cloud, slowly making its way to the
bottom of the bay.

PAUL GREENFIELD, SE QLD HEALTHY WATERWAYS PARTNERSHIP: Gradually it will settle, and therein lies
the problem. Firstly, it impedes light, so light won't reach the bottom parts of the bay, and those
things that require light, like sea grass, will be badly affected.

MILES YEATES: Some of our there threatened species that are so used to living here in Moreton Bay,
with the lush sea grass pasture, may not find it's like that for the next few months.

PETER MCCUTCHEON: Researchers also want to determine how many heavy metals, pesticides and
contaminants from sewerage overflow have made their way out to sea. The chair of a scientific panel
advising the Queensland Government on waterways says this information is vital.

PAUL GREENFIELD: That in fact is the most immediate problem, because that will impact our ability
to eat seafood from the bay, it will impact on livelihoods and it will impact on the recreational
value of the bay going forward. So there are surveys being done at the moment to determine how
significant that is.

PETER MCCUTCHEON: In the longer term, the flood and its effect on Moreton Bay raises questions
about future development along key waterways.

BILL DENNISON: I think of it kind of like a bit of a heart attack, you know. Here we have this
great artery running through this vibrant city, this fantastic Brisbane River that has been
embraced by the city, and all of a sudden we had this major event. So we have to do something - we
have to listen to what that tells us. We need to think of the river not as a pipe, but as a living
being. And just as the blood coursing through our body, we need to look after it.

PETER MCCUTCHEON: Moreton Bay has been hit by big floods many times before, but this is the first
time it's experienced a massive inflow in the 21st Century, with all the accompanying pollutants of
modern life.

MILES YEATES: There is a human dimension to this in that a lot of the contaminants coming down the
river are sourced from sewerage treatment plants from sediment from agricultural areas. They
contain chemicals that you wouldn't normally find in the bay.

PETER MCCUTCHEON: Scientists are cautiously optimistic the bay is resilient enough to cope with the
shock, but the disaster of two weeks ago is still being played out.

BILL DENNISON: We're not out of the woods yet. We still are in the middle of the cyclone season. We
have cyclones forming out there in the Pacific Ocean. So, we've got a very watchful brief and
particularly in the next two weeks; that's the most vulnerable period.

TRACY BOWDEN: Peter McCutcheon reporting there.