‘Overlooked’: 14,000 invertebrate species lost habitat in Black Summer bushfires, study finds

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More than 14,000 species of invertebrate lost habitat during Australia’s 2019-20 bushfires, according to a post-fire analysis that has recommended a doubling of the number of species listed as threatened.

The research, prepared for the federal government by scientists with the national environmental science program (NESP), found the number of insects, spiders, worms and other invertebrates affected by the disaster was much greater than the tally of vertebrates impacted.

But that fact was largely overlooked due to a focus on more popular animals such as the koala.

The NESP study warns the true figure is likely to be far higher than 14,000 because so many Australian invertebrates are either undescribed or have no data available through which to measure declines.

At least one animal, the Banksia montana mealybug in Western Australia, is considered likely extinct as a result of Black Summer fires in that state.

“If you look at the most affected animals by the fires, about 95% of them are invertebrates,” said John Woinarski, a professor at Charles Darwin University and one of the authors of the research. “And it has had very little public attention.”

Australia has 111,233 described terrestrial and freshwater invertebrate species. Though they receive less attention than Australia’s unique mammals and birds, they perform important roles in the ecosystem, such as pollination or as a food source for larger animals.

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Others are detritivores that break down ecosystem debris – such as leaf litter – which cycles nutrients back into the soil, fostering plant growth and reducing fuel loads for fire.

The scientists were able to use existing records and fire maps to compile enough data for 32,164 invertebrates, while noting that for some species they were working with, there were only one or two known records of their existence.

The scientists found that 14,159 – roughly half of those species – had at least some habitat burnt by the fires, with 1,209 having had either 50% of their known range burnt by fires of any severity or 30% by fires of high severity.

Of those 1,209, the scientists had enough data to recommend the government add 60 species to Australia’s list of nationally threatened invertebrates, which currently totals 63.

Jess Marsh, a scientist on Kangaroo Island and co-author of the research, said the 60 they had recommended for listing were “just the ones we know about” – meaning there was enough data available to make them eligible for an assessment by the threatened species scientific committee.

It is up to the committee to consider those species before making a recommendation to the federal government as to whether they should be listed as threatened under the Environment Protection and Biodiversity Conservation Act.

“A lot of species that are likely the most vulnerable wouldn’t be eligible because there’s not enough data,” Marsh said.

Among the invertebrates the scientists recommended for listing were the Kangaroo Island assassin spider, millipedes of the genus Atelomastix in Western Australia, and a type of caddisfly found in New South Wales and Victoria whose larvae live in water and are sensitive to chemical changes caused by fire.

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Marsh has researched the Kangaroo Island assassin spider for several years. It is one of several ancient species of assassin spider found around Australia, so-named because they eat other spiders. They are sometimes referred to as pelican spiders for their unusual appearance that resembles the shape of the water bird.

They are considered vulnerable to fire because they live in leaf litter found in low-lying vegetation that is more likely to burn when bushfires hit.

Before the fires on Kangaroo Island, the island’s assassin spider was known from only one location, which was completely destroyed in the 2019-20 disaster.

Marsh said two specimens had since been discovered at another location 4km away.

She said it highlighted a problem that was common for many invertebrates – that their habitat ranges are sometimes so small a single fire could be enough to affect the entire species.

Libby Rumpff, another co-author based at the University of Melbourne, said the work also underlined the conservation difficulty for so-called “data deficient” species that attracted little attention or funding.

“If you’re labelled as data deficient, you get put in a box and just have to hope someone does something about it,” she said.

“Many invertebrates are poorly known because they’re rare, or have restricted distributions, and because there’s bias towards vertebrates and the more charismatic groups.”

Marsh said she hoped the analysis would prompt a rethinking of conservation approaches for Australia’s invertebrates. That could include conservation planning at a landscape level that protected entire habitat areas with high levels of endemic invertebrates, she said.

Such an approach could mean “we can protect species we know about but also the ones we don’t know about”.

“Invertebrates have been overlooked and have not been valued from public opinion all the way up to decision-makers. That needs to change,” Marsh said. “We need to find a way forward for including invertebrates in conservation planning.”

Woinarski said that if even the 60 species they had recommended were listed as threatened, it would represent a profound change in the conservation status of Australia’s invertebrates.

He said there were other species Australia could be losing while being unaware of it.

“Invertebrates are the stuff of life. They are the fulcrum of much of the food webs in Australia. If you stuff up the invertebrate community, then inevitably there will be consequences for things other than those species alone.”

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