Floodplain primed for fish kill
WITH the onset of summer monsoonal rains, the Richmond River floodplain is now primed for another devastating fish kill.
The warning comes from Lismore-based wetlands scientist David Pont, part of the Water And Carbon Group, a private venture seeking to make carbon-sink ‘farming’ a reality.
However Mr Pont’s colleague Michael Woods, floodplain facilitator with Richmond River County Council, warns that fish kills from summer floods are a part of the Richmond River’s complex make-up and there is not much we can do to prevent them.
Mr Pont begs to differ, saying the worst contributors to fish kill events are unprofitable grazing paddocks on parts of the floodplain that would be better used as carbon sinks – in the form of lagoons, reed beds and paperbark forests.
He said land forested with melaleucas and casuarinas would qualify for funding under carbon credits scheme, as outlined in the Kyoto protocol with real income generated to farmers that are currently creating avenues for further fish kill.
But all that rests on whether the Federal Government adopts a carbon pollution reduction scheme.
The areas of land that are the real culprits when it comes to creating de-oxygenated water during a summer flood are lands around Rocky Mouth Creek, Tuckean Swamp and Berminghams Flat near Coraki.
Analysis of the benefits of a potential scheme involving 10,000 ha were detailed by the Water and Carbon Group, setting aside 1000 ha as lagoons and 3000 ha to be left growing rushes and reeds. Neither of these areas would qualify for carbon credit funds under a Kyoto scheme.
But Mr Pont said the remaining 6000 ha planted with casuarinas and paper bark trees had the potential to return $100m over a 30 year period for an initial outlay of $25m.
“That is a four-fold return,” Mr Pont said.
Meanwhile, Mr Woods said such a scheme would probably fail to stem the likelihood of a summer flood fish kill, although anything that could be done to minimise the effect would do good.
He said summer floods spread out onto a huge lower river flood plain and stagnated there, covering vegetation with water that warmed to more than 25 degrees.
If that flood water sat on the floodplain at that temperature for more than three and half days the result was an inland sea of de-oxygenated water.
When the river dropped in height those ‘black waters’ were released into the main channel, creating a river of death for most species.
Mr Woods agreed that back swamps, or areas of low land that typically filled with water during a flood, needed to be ‘decoupled’ from the main river by filling in old drains.
But funding for this sort of project was currently at a ‘low ebb’.
“Clearly anything we can do would help,” he said.