Workers from the Deniliquin Local Aboriginal Lands Council have been turning heads in the Deniliquin Waring Gardens as they continue efforts to control deep water arrowhead in the lagoon.
It is part of the larger Deniliquin Lagoons Restoration project, which is run in conjunction with Edward River Council and the Edward Wakool Angling Association.
The removal will continue over three weeks.
EWAA scientific officer and ecologist Dr John Conallin said arrowhead — or sagittaria as it is also known — is booming in the lagoon and the river systems.
A noxious weed, it can be hard to eradicate completely, but Dr Conallin said regular control efforts would be undertaken to try and limit its spread in the lagoons.
‘‘The idea of slashing the sagittaria now, is to have the lagoons looking nice for the approaching tourism and festive season,’’ Dr Conallin said.
‘‘Until we can figure out how to remove it completely, control will continue at regular intervals — cutting it back and partially removing it.
‘‘We will avoid any control between November and March however, as this is when the catfish in the lagoons will be nesting and breeding.’’
Control of the red blooms that have appeared in the lagoons — a weed called azolla — is taking place at the same time, using a ‘‘biological activator’’.
Azolla is an Australian native fern that is common in many waterways, and is commonly used as a decorative feature in garden ponds.
It supports a nitrogen-fixing cyanobacterium in its fronds, which is released when the plants decay.
It can quickly spread to cover open areas of water and may build up in stationary water bodies, particularly if nutrients levels are adequate.
The Lagoons Restoration Project started in 2013, when the lagoons were drained, cleaned and cleared of non-native aquatic species and non-native flora.
In the years that have followed native plants and fish have been added to the system.
Dr Conallin said, based on sampling taken last week, the fingerlings released in the lagoons so far are showing promising signs.
‘‘In that sample I got some of the Southern Pygmy Perch fingerlings from the re-stocking we did at the start of the year, and by looking at their condition I would say they have already bred this year,’’ he said.
‘‘We should therefore hope to see some juveniles appear over the summer.
‘‘We sample seasonally, coming in to summer before breeding, to ensure the species released are thriving as planned.
‘‘And we expect to release some more fish in to the lagoons soon.’’
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