Unexpected roadblock leads to innovative solution for lungfish

Lungfish Habitat Rehabilitation Program: Phase 1 complete

Australian Lungfish (Neoceratodus forsteri) are a protected species, endemic to catchments in South East Queensland (SEQ) and are listed as Vulnerable, and a Matter of National Environmental Significance under the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act).

We are now a year into an innovative Lungfish Habitat Rehabilitation Program which is restoring critical Australian Lungfish breeding habitat in the Brisbane River. We thought it would be a good time to check in on the progress made so far.

To recap, the project is re-establishing submerged aquatic plants damaged during floods to ensure the long-term survival of the Australian lungfish in South East Queensland rivers. The plantings will also improve river health and water quality of Brisbane’s major source of drinking water.

We are pleased to report that the active collaboration between Healthy Land and Water, Seqwater, and Griffith University has achieved significant progress and some surprising findings in the project’s first year.

Planting has been undertaken across three sites in the Mid-Brisbane River at Burtons Bridge, Fielding Road Reserve and Atkinson’s Crossing.

The installation of submerged aquatic plants (Vallisneria sp.) on tiles of biodegradable jute matting directly into the riverbed was trialled at these sites in early 2020 followed by photo and drone monitoring.

This initial work has had mixed results as within a few days post planting, the team noticed at the Atkinson’s Crossing site that the plants had been browsed by some type of animal species right down to the roots. For some of the plants, even the roots had been eaten!

After a few weeks, this browsing was observed at the other two sites as well.

Having the plants eaten before they had a chance to grow was not part of the plan, so the team had to find out what was eating the plants and work out if they could stop it.

Healthy Land and Water team undertaking drone monitoring.

A combination of fresh plants protected by cages as bait and motion cameras identified the surprise culprit – lungfish.

The plants were installed for the lungfish to lay eggs in, not as a food source, so this was not going to help them long-term.

Despite the considerable damage to the plantings by hungry lungfish, it is likely some of the dislodged plants would have drifted downstream and established new colonies in protected backwaters, just like they would naturally.

The second round of Griffith University monitoring will assess if this is the case.

Fresh planting tiles were installed at the Atkinson’s Crossing site; half were protected by a cage and half were left unprotected and motion trigger cameras were set up to record the area.

Whilst a range of aquatic wildlife was sighted, the cameras recorded Lungfish spending a substantial time directly above the newly installed planting tiles.

The unprotected tiles were completely depleted within a few days of planting, while the tiles protected by cages were not. The before and after photos of the unprotected planting tiles show just how voracious the lungfish were, ripping the jute mat apart to get every last part of the plant’s roots!

Before  After
Caged tiles to test establishment while protected from lungfish browsing at Burtons Bridge.

 

Quick thinking leads to time-saving solutions

The team was initially going to be sourcing the plants from a nursery, however, when the team found out the nursery was no longer able to supply the plants, they had to come up with another solution.

Very few nurseries have the capacity to grow Vallisneria sp. And with the planting deadline fast approaching, the team decided to source pre-made pools to grow the plants themselves, saving valuable time.

The team installed cameras to remotely monitor the water levels of the pool, so they knew when they needed to visit the site to top them up. This saved the team even more time.

 

Growing Vallisneria sp. in swimming pools.

What is happening in Phase 2?

The team says that the intel gained in the first phase of the project has been invaluable in informing how to refine and improve the approach they will now use for the next phase.

In a nutshell:

  • Plants will be ready to install in the riverbed by April/May.
  • The plants will be established in larger clumps and protected by temporary cages.
  • The team will likely place the plants in areas with a faster current which should reduce how much the lungfish eat them when the cages are eventually removed. This will also help spread the plants further downstream when they reproduce.
  • The team has refined the drone monitoring system so they will be able to keep an eye on how well the plants spread, without having to wade into the river.

Click here to read more about the program.

 

This project is supported by Seqwater.

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