Lungfish Habitat Rehabilitation Program

Seqwater, Healthy Land and Water, and Griffith University have teamed up to give the Australian Lungfish (Neoceratodus forsteri) a helping hand by restoring their critical breeding habitats in the Brisbane River.

The innovative program aims to re-establish the macrophytes – the submerged aquatic plants – that were damaged in significant floods and are vital for lungfish breeding and maintaining a healthy lungfish population. Informed by recent research findings, and following a citizen science trial run by Seqwater Senior Scientist Dr David Roberts as well as volunteers from the Australia New Guinea Fish Association (ANGFA), this program will undertake extensive planting of the macrophytes within the Brisbane River between Wivenhoe Dam and the Mount Crosby Water Treatment Plant.

This habitat rehabilitation program forms part of a broader strategy that Seqwater has developed 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.

 

Protecting the Lungfish

The Australian lungfish is a prehistoric species that first appeared in the fossil record 380 million years ago, well before dinosaurs. The Australian lungfish is the oldest known living vertebrate, remaining unchanged from its current form for over 100 million years, and is listed as a vulnerable species under the Commonwealth Environment Protection and Biodiversity Conservation (EPBC) Act 1999.

The Australian lungfish belong to a rare group of fish known as the lobbed finned fishes, that have thick fleshy paddles for fins, that have a well-developed internal bone structure, unlike most other fish. The Australian lungfish has a single lung, whereas the other four species of lungfish -found in Africa and South America – have paired lungs. Under most conditions it breathes exclusively using its gills however, during dry periods when streams are stagnant or when being active, they can surface to breathe air.

The Australian lungfish naturally occurs in the Mary and Burnett Rivers, and has been translocated to other rivers in South East Queensland, including the Brisbane River in the late 1800’s. They breed from August through to December and their fertilised eggs stick to submerged aquatic plants, known as macrophytes. Several factors are putting pressure on lungfish populations, including loss of breeding habitat, barriers that block access to, or inundate breeding habitats, egg predation by invasive fish and extreme weather conditions.

Seqwater closely monitors lungfish populations and have developed a population model to assess what factors are most important to the ongoing sustainability of the population. While the numbers of Australian lungfish in the Brisbane River remain good, their breeding opportunities have been impacted by significant floods when the macrophytes they lay their eggs in were ripped out of large areas of the riverbed and have not recovered since. Recent surveys have confirmed very few juvenile lungfish are found in the river, which is not typical for the Brisbane River, but does occur periodically in the Mary and Burnett Rivers. This indicates that the normal reproduction cycles in the Brisbane River have been impacted. Without intervention, the reduced breeding opportunities may start to affect the population in the Brisbane River.

 

How does the program work?

The program involves re-establishing the rivers macrophytes – that have been grown in plant nurseries on tiles of biodegradable jute matting, then transplanting them into the riverbed. The jute planting tiles are kept in place using stakes made from corn starch which break down after a few years. To transplant the tiles, the team wades out into knee deep water, digs a shallow hole in the riverbed, places the tile in the hole and secures it to the riverbed using the stakes and covers them in a layer of sand and rocks. The tiles must be planted in shallow water, as the macrophytes need sunlight to grow, and these areas of shallow gently flowing water are the ideal conditions for lungfish to lay eggs once the macrophytes establish.

Griffith University are conducting research to evaluate the effects of different water depths, river speed and riverbed material on the success of the planting program. The team will also trial monitoring the establishment and growth of the macrophytes using drones as a faster and safer alternative to wading into the river. Three sites in the Brisbane River below Wivenhoe Dam have been replanted this year, with plans for another six locations over the next two years. In total the program aims to plant over 100 square meters of macrophytes which will grow and expand to new areas of the river over time. Healthy Land and Water and Seqwater plan to publish the findings from the program to share the information with counterparts working on riparian restoration and lungfish projects in the Mary and Burnett river systems.

 

Photo credit: Fishes of Australia

 

Lungfish Facts

  • Lungfish are relics of ancient fish groups related to the ancestors of all land-dwelling animals, including amphibians, reptiles, birds, and mammals.
  • Lungfish can grow to 1.5 metres long and weigh up to 40kg.
  • Lungfish eat a varied diet of frogs, tadpoles, small fish, snails, shrimp, earthworms and plant material.
  • Lungfish teeth have enamel similar to human teeth.
  • Lungfish can live to at least 77 years old in the wild and well over 100 years old in captivity.
  • Lungfish have one of the largest genomes of the animal kingdom, about 17 times bigger than a human genome.
  • Australian lungfish cannot survive for extended periods out of water despite having a fully functioning lung.

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