Striking at the heart of Spartina

Spartina, also known as Rice Grass or Cordgrass, was introduced to Australian farms in the 1920s and has since become aggressively invasive, competing with indigenous plants, degrading waterbird and fish habitats and restricting waterways.

For environmentally sensitive and important areas like Corner Inlet, Spartina is particularly problematic. Corner Inlet provides a natural estuary habitat for important fish populations, and a feeding and breeding site for local birds and internationally significant migratory species.

Spartina infestation is smothering critical feeding and breeding habitats for these birds and fish, as well as choking intertidal mudflats.

In the past year, the Australian Government’s National Landcare Program has funded a targeted Spartina control program, as part of the Corner Inlet Connections (CIC) program.

Although Spartina control has been part of CMA activities in Corner Inlet for several years, the current program focused on on-ground treatment of Spartina in the Agnes and Franklin rivers and the western tributaries of Corner Inlet.

West Gippsland Catchment Management Authority contracted Envirogain, an environmental services company, to treat the Spartina.

Envirogain specialises in pest, plant and animal control and revegetation and Managing Director, Simon Harrick, said they have been working on Spartina infestation in Corner Inlet for seven years.

“The biggest effect we see on the ground is that Spartina overtakes the saltmarsh areas. It effects the hydrology of whole creek systems and causes sediment to accumulate around the creek entrance, blocking them up,” he said.

Saving the saltmarsh
Saltmarsh filters pollutants, stabilises sediments, traps and processes nutrients and protects the shoreline from erosion.

Simon said the ongoing control programs are making a real difference.

“Revegetating saltmarsh areas is really difficult. That’s why protecting what is there is so important. You just can’t replace it.

“We are seeing natural saltmarsh regenerating in a lot of areas. Spartina infestation is going down; we are getting it under control.”

In fact, the program has been so successful that in some areas, such as Dead Horse Creek, herbicide use is down by 96 per cent.

Simon said the past year has involved painstaking on-ground work to ensure the Spartina does not re-establish.

“It’s time consuming to hunt for Spartina in muddy saltmarsh areas. Our herbicide use is dropping, but the time spent to find it is increasing,” Simon said.

“We’re working on foot, with a backpack spray, or using kayaks. It’s the intensity of man hours that’s increased, rather than herbicide use.”

The team uses kayaks to get to areas that are inaccessible by road or foot.

“The kayaks have 40 litre tanks with a hose reel, so the team can beach the kayak and then get out and spray.”

Simon estimates that his team has probably spent around 370 man hours on the ground.

“We would spend around 40 of that in the kayaks and the rest on foot,” he explained.

“In the past year, we’ve covered around 200 hectares this way.”

Finding the target
A targeted approach to Spartina control has multiple benefits. It allows the team to find and treat small outbreaks and reduces the impact on the environment.

The program uses Fusilade Forte, a herbicide that is not lethal to saltmarsh flora and selectively targets grasses and Spartina. The CMA and RMIT have undertaken research to understand any associated risks. To date, results have shown that with judicious use, there are no detrimental effects on shellfish and seagrass, an important consideration in such an environmentally sensitive area.

Simon said the on-ground approach complements other control methods such as helicopter spraying.

“There was a lot more helicopter work in the beginning, but it has limitations. If Spartina is growing under a mangrove, the helicopter won’t see it.

“Sometimes, if there are areas of big infestations, we use a 4-wheel drive rig if we can get access.”

But being on-foot is an essential part of the control program.

“Spartina is easy to identify when it grows in mudflats, but it can get tricky when it’s growing amongst the native glasswort. That can be time consuming,” Simon said.

“We mark all the points where we locate the Spartina using a smart phone app. We have a record of all the places we’ve sprayed, and we coordinate our data with the helicopter spray.”

Getting up close is the only way to nip new Spartina outbreaks in the bud. And knowing exactly where to look is important as well.

“You might just have one centimetre of Spartina starting, then within a year, it’s three centimetres high.”

Recording Spartina locations has also allowed the Envirogain team to contribute to mapping research being done in areas of Corner Inlet, particularly around the Agnes and Franklin rivers.

Staying focused
Despite the close focus and effectiveness of the program, Simon says Spartina remains a serious issue.

“Even with these improvements, it’s still an issue in the area. It’s still a high threat weed. Because it’s tidal, Spartina gets carried by water, so its spread area is wherever the water goes.”

But he is confident that it is possible to imagine a future where Spartina is totally eradicated from Corner Inlet.

“It’s amazing seeing the results each time we go out. A lot of headway has been made. Now is not the time to take the foot off the pedal,” he said.

“It only takes two to three years for a small patch of Spartina to become a serious threat. It can multiply four to six times over that period.”

The ground-based treatment of Spartina in the Agnes, Franklin and Western Tributaries estuaries in Corner Inlet has been delivered by West Gippsland Catchment Management Authority through funding from the Australian Government’s National Landcare Program.

Simon Harrick, MD of Envirogain
Simon Harrick, Managing Director of Envirogain, says the ongoing Spartina control programs are making a big difference.
Spartina in Corner Inlet
Spartina infestation in Corner Inlet is smothering critical feeding and breeding habitats for birds and fish, as well as choking intertidal mudflats.