The population of a local species of scorpion serves as an "ecological barometer" in Australia, a new study suggests.
Researchers from La Trobe University in Melbourne, Australia, observed that in the presence of their natural predators, such as the nocturnal marsupial bilbies, native scorpions thrive in Australia's landscapes.
The paper, submitted to the journal Ecology, has been accepted for publication and has already completed full peer review as of September 6.
Scorpion Population in Australia
Seeing the scorpion as an "ecological barometer," lead researcher Heloise Gibb raised inquiries on whether scorpions have always been this populous or if this number was the result of the decline in other species' populations within the same ecosystem.
With growing studies of unprecedented species extinction, the La Trobe University team set out to identify evidence for ecological cascades. Noting that with the arrival of Europeans in the Australian continent, endemic mammals have either declined in numbers or eventually became extinct. Researchers added that the ecological roles of this wiped out species are "poorly understood."
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The lead researcher also explained that large, native scorpions that grow up to 9 centimeters are abundant in the Mallee, an area in the northwestern part of the state of Victoria in Australia. He added that the location of their study, the Scotia Sanctuary of the Australian Wildlife Conservancy, located in New South Wales, they were able to determine a density of 600 scorpion burrows per hectare of land.
"The Mallee, in particular, can seem extremely harsh and even lifeless in the heat of summer days, but it comes to life at night, with geckos, spiders, scorpions, and many other nocturnal animals," Gibb explained in a press release from La Trobe University.
During their surveys, their team was equipped with UV-proof glasses and UV torches to find scorpions in the dark, in sweltering Australian summer nights. Professor Gibb explained that while their vision is limited by the UV-proof glasses, it helps them in the scorpion hunt since these invertebrates appear fluorescent under UV torches. So, in the night, they easily find scorpions. Furthermore, they used tongs in picking up scorpions by the tail, noting the average sizes of the creatures and for the safety of their team.
Effect of Mammalian Reintroduction
Re-introducing threatened mammals, especially burrowing species like bilbies, might also offer insights in restoring local Australian ecosystems. Professor Gibb admitted that while reintroduction can help restore their ecosystems, it's difficult to describe the exact conditions since they do not know what Australian ecosystems were like 200 years ago before Europeans arrived.
He also stressed that reintroductions of species might also lead to other unexpected consequences. For example, over predation towards one species might upset the balance and cause an increase in the population of another species, cascading from predatory animals down to plants.
Through ecological surveying and long-term exclusion and disturbance experiments, Gibb's team was able to establish that the scorpion population is negatively affected by the introduction of threatened, native mammals that also act as their natural predators.
Mammal reintroduction also affected the population of spiders, another predatory invertebrate group in the area that works to regulate the insect population.
