Control of the invasive water weed, Hymenachne sp. discovered at Keating's Lagoon, has taken five years. 

These days the wetland menace is like a boxer on the ropes, and has been since late 2012.

Consistent weed control efforts conducted by Cape York Weeds and Feral Animals Program (CYWAFAP), Queensland Parks and Wildlife Service and South Cape York Catchments, has enabled Keating’s Lagoon to flourish, providing important habitat for numerous wetland bird, frog and fish species.

Located five kilometres south of Cooktown, Keating’s Lagoon Conservation Park is reknowned for its rich wetland biodiversity, visitor accessibility  and its significance for scientific study and educational purposes.

The area’s Traditional Owners dubbed the lagoon Mulbabidgee, and the waterway was declared a conservation park due to the ecological value of its freshwater wetlands and surrounding habitat.

In 2008 South Cape York Catchments successfully excluded feral pigs from the lagoon with fencing, documenting a dramatic improvement in the health of the wetland. Hymenachne sp.produced a new and serious threat to the conservation and ecological values of the lagoon.

Trevor Meldrum, Pest Management Officer from CYWAFAP, says the key to the success of the eradication program is regular and sustained follow-up, with the result of  reducing the seed bank in the soil to allow native plant species to reestablish. Hymenachne sp. is a semi-aquatic grass introduced into Australia as cattle feed, and now escaped from cultivation, is regarded to be amongst Austraila's worst  weed infestations.  Hymenachne sp is a serious threat to wetland survival and river system health.  

 Hymenachne has the abililty to out-compete all other wetland plant species, quickly covering the entire surface of a water body to ultimately impact fish and other aquatic  life. Dense stands block drains, cause flooding and reduce water quality.

There is now minimal Hymenachne surviving in the Lagoon according to Trevor.

“Nonetheless it is necessary to regularly monitor the area and quickly remove any new plants as they emerge,” he said.

With continued funding from Cape York Natural Resource Management for the irradication of Hymenachne sp, the weed has little chance of impacting the future health and functioning of Keating’s Lagoon.

By Jason Carroll, South Cape York Catchments