Summary

While most invasive plants, invasive animals and pathogen distributions are limited in extent, the severity of their threat is variable. Most invasive species and pathogens have minor impacts on the attributes of K’gari’s World Heritage Outstanding Universal Value. Our management programs have actively targeted some of these high-risk pest species.

Invasive plants

Several invasive plants of concern on the island include:

• three weeds of national significance
• nine locally- listed (Fraser Coast Council Local Law No. 3) weeds
• four other environmentally significant invasive plants (some restricted invasive plants under the Biosecurity Act 2014)

Invasive animals and pathogens

Several invasive animals and pathogens of concern on the island include:

• Insects: coastal brown ant (Pheidole megacephala) and pandanus leafhopper, (Jamella australiae)
• feral animals: feral cat (Felis catus), cane toad (Rhinella marina), feral horse (Equus caballus), Indian Myna bird (Acridotheres tristis), and feral pig (Sus scrofa).
• pathogens (disease-causing organisms): Myrtle rust (Austropuccinia psidii) that impacts Myrtaceae plant sap and Chytridiomycosis caused by the fungus Batrachochytrium dendrobatidis (an amphibian chytrid fungus disease) that impacts threatened acid frogs.

Myrtle rust

Myrtle rust is exceptionally difficult to control and is an ongoing concern due to its:

• pervasiveness
• speed of transmission
• difficulty of management

We have found myrtle rust in various ecosystems on the island, including rainforest, coastal heath, and paper bark wetlands.

Myrtle rust is caused by the introduced exotic airborne rust fungus (Austropuccinia psidii).

We are researching myrtle rust at both species and plant community levels to assist in the development of species conservation and management plans.

Myrtle rust impacts

Myrtle rust poses a significant threat to Melaleuca wetlands and rainforest margins. The latter is an existential threat to the long-term viability of the island’s unique rainforests as it prevents the recolonisation of areas by the rainforest because rainforest pioneer species include many myrtle rust-sensitive Myrtaceae.

Many affected species are traditional food sources, e.g., midyim berries  (Austromyrtus dulcis), which are medicinal or otherwise culturally significant to the Butchulla people.

Following the 2019-20 bushfires, we detected myrtle rust where it was previously not located. The development of epicormic regrowth (growth from a previously dormant bud) and young seedlings after fire are ideal for the development and spread of the rust fungus.

We have now detected myrtle rust on satinay (Syncarpia hillii), an important attribute of the island’s Outstanding Universal Value.

Biosecurity monitoring

We are now enhancing our biosecurity capacity concerning myrtle rust on the island. Targeted monitoring will help identify its impact on the island and where to establish study sites to determine the long-term effects.

Unchecked, the potential introduction of other invasive species is inevitable, and the impacts from the introduction of any of these species would be devastating:

• red fire ant (Solenopsis invicta)
• yellow crazy ant (Anoplolepis gracilipes) (established nearby on the mainland at Booral)
• polyphagous shot hole borer (Euwallacea fornicatus)
• Phytophthora dieback (Phytophthora cinnamomic)

These species may be introduced to K’gari on vehicles, machinery, equipment, boots, clothes or camping gear. This current and potential threats are currently considered high.

Threat assessment

The assessment of threats is outlined in the K’gari (Fraser Island) Conservation Outlook Assessment from 2014, 2017 and 2020. Reporting of Outlook Assessment has changed from every 3 years to every 5 years and the next report is due in 2025.

Increased visitation is acting as a driver for a number of threats to the property, including the introduction of invasive species. Management is good and some species (like horses) have been almost totally removed. However, work on cane toads and ants has been less successful.

We actively manage weeds, plant diseases and feral animals (particularly cats), while present, are in low numbers are subject to active management, but they are increasing in frequency and severity (e.g., myrtle rust) and pose a significant threat to the values directly associated with the World Heritage List criterion ix (ecological and biological processes) and vegetation community structure, floristics, and extent.

The Queensland Government is working in collaboration with the Butchulla Land and Sea Rangers to enhance biosecurity and awareness on the island. Biosecurity management initiatives, which are intended to reduce the likelihood of additional invasive species being introduced, are also underway on the island.