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Study reveals rich but vulnerable picture of Australia's island frogs and fish

Study reveals rich but vulnerable picture of Australia's island frogs and fish
The striped rocketfrog (Litoria nasuta) is widely distributed both on the Australian mainland and on the country's islands. Credit: Samuel Ho

A first database has been compiled of the frog and freshwater fish species on hundreds of Australian islands.

It was developed at the University of Queensland to help target conservation efforts across Australia's 9,300 islands using information from multiple sources, including the Atlas of Living Australia platform and thousands of published wildlife surveys. The has been published in Diversity and Distributions.

Researcher Samuel Ho from UQ's School of the Environment said the study found that 536 Australian islands had , ranging from deep lakes to wetlands and seasonal creeks.

"Across those islands, there are 102 from six different families with a wide range of sizes and behaviors," Mr. Ho said.

"We recorded 95 freshwater , some of which are endemic to a particular island, along with nine non-native species."

The project looked at the that influence the presence of frog and fish species on islands, their threat levels and risk of extinction.

"Frogs were more common on islands close to the mainland with humid climates and low temperature variability, while the number of species was higher on larger islands," Mr. Ho said.

Study reveals rich but vulnerable picture of Australia's island frogs and fish
The ornate burrowing frog (Platyplectrum ornatum) is one of the most frequently occurring amphibian species on Australian islands. It can burrow beneath the surface and may remain dormant underground during the day or throughout dry seasons, enabling it to survive on drier islands. Credit: Samuel Ho

"Within the database, 14 of the recorded species are known to be threatened, most of them freshwater fish.

"While only 2.5% of Earth's surface water is freshwater, these habitats are highly biodiverse.

"Freshwater ecosystems on islands are particularly vulnerable to human-induced threats such as habitat destruction and rapid climate change, and they are often understudied.

"We hope this database will help prioritize and pinpoint Australian islands that need more comprehensive surveys."

The project is part of a wider long-term study of Australia's islands and their conservation by UQ's Biodiversity Research Group, led by Professor Salit Kark.

Professor Kark said the research team had developed a database of threatened plant and animal species for all of Australia's 9,300 islands.

Study reveals rich but vulnerable picture of Australia's island frogs and fish
The ornate rainbowfish (Rhadinocentrus ornatus) is a Vulnerable species found only in parts of eastern Australia, including offshore islands such as North Stradbroke Island (Minjerribah). They are highly variable in coloration, ranging from pale silvery tones to vibrant blue and red, depending on the population and environment. Credit: Samuel Ho

"Islands are hotspots for species that do not occur anywhere else on Earth," she said.

"But a combination of their isolation and can lead to species becoming threatened on islands and, indeed, many extinctions have occurred on islands globally.

"This new database helps us better understand the patterns and processes at play on islands to help direct future conservation and management actions for these valuable and sensitive ecosystems, including highly threatened groups such as amphibians and freshwater fish.

"We hope the database will be used by local island communities, managers, researchers and other organizations to support island communities and biodiversity."

The Australian amphibian and freshwater fish database is open access.

More information: Samuel C. L. Ho et al, Diversity and Distribution of Amphibians and Freshwater Fishes on Australian Islands, Diversity and Distributions (2025).

Journal information: Diversity and Distributions

Citation: Study reveals rich but vulnerable picture of Australia's island frogs and fish (2025, August 14) retrieved 27 August 2025 from /news/2025-08-reveals-rich-vulnerable-picture-australia.html
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