Light and shade: how the natural ‘glazes’ on the walls of Kimberley rock shelters help reveal the world the artists lived in

Helen Green, The University of Melbourne and Damien Finch, The University of MelbourneThe Kimberley region is host to Australia’s oldest known rock paintings. But people were carving engravings into some of these rocks before they were creating paintings.

Rock art sites on Balanggarra Country in the northeast Kimberley region are home to numerous such engravings. The oldest paintings are at least 17,300 years old, and the engravings are thought to be even older — but they have so far proved much harder to date accurately.

Cupules, or circular man-made hollows, ground into a dark mineral coating at a rock art site on the Drysdale River, Balanggarra country.
Photo by Damien Finch

But in research published today in Science Advances, we report on a crucial clue that could help date the engravings, and also reveal what the environment was like for the artists who created them.

Some of the rocks themselves are covered with natural, glaze-like mineral coatings that can help reveal key evidence.

What are these glazes?

These dark, shiny deposits on the surface of the rock are less than a centimetre thick. Yet they have detailed internal structures, featuring alternating light and dark layers of different minerals.

Our aim was to develop methods to reliably date the formation of these coatings and provide age brackets for any associated engravings. However, during this process, we also discovered it is possible to match layers found in samples collected at rock shelters up to 90 kilometres apart.

Radiocarbon dating suggests these layers were deposited around the same time, showing their formation is not specific to particular rock shelters, but controlled by environmental changes on a regional scale.

Dating these deposits can therefore provide reliable age brackets for any associated engravings, while also helping us better understanding the climate and environments in which the artists lived.

Marsupial tracks scratched into a glaze like coating at a rock art shelter in the north east Kimberley.
Photo by Cecilia Myers/Dunkeld Pastoral Company; illustration by Pauline Heaney/Rock Art Australia

Microbes and minerals

Our research supports earlier findings that layers within the glaze structure represent alternating environmental conditions in Kimberley rock shelters, that repeated over thousands of years.

Our model suggests that during drier conditions, bush fires produce ash, which builds up on shelter surfaces. This ash contains a range of minerals, including carbonates and sulphates. We suggest that under the right conditions, these minerals provided nutrients that allowed microbes to live on these shelter surfaces. In the process of digesting these nutrients, the microbes excrete a compound called oxalic acid, which combines with calcium in the ash deposits to form calcium oxalate.

A: dark coloured, smooth mineral coating at a Kimberley rock shelter; B: alternating layering, as seen in the field; C: alternating layering as seen in a cross-sectioned coating under a microscope.
Photos by Cecilia Myers; microscope image by Helen Green

As this process repeats over millennia, the minerals become cemented together in alternating layers, with each layer creating a record of the conditions in the rock shelter at that time.

Samples of the glazes were collected for analysis in close collaboration and consultation with local Traditional Owners from the Balanggarra native title region, who are partners on our research project. Using a laser, we vaporised tiny samples from the coatings to study the chemical composition of each layer. The dark layers were mostly made of calcium oxalate, while lighter layers contained mainly sulphates. We propose darker layers represent a time when microbes were more active and lighter layers represent drier periods.

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How climate change is erasing the world’s oldest rock art

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Linking the layers

These dark calcium oxalate layers also contain carbon that was absorbed from the atmosphere and digested by the microbes that created these deposits. This meant we could use a technique called radiocarbon dating to determine the age of these individual layers.

Using a tiny drill, we removed samples from distinct dark layers in nine glazes collected from different rock shelters across the northeast Kimberley.

A: micro-drilling samples from individual layers for radiocarbon dating; B: Laser ablation maps showing the distribution of the element calcium within the different layers; C: radiocarbon dating of individual layers identified four key growth periods.
Photo by Andy Gleadow; illustration by Pauline Heaney

Despite coming from different locations, these layers all seem to have been deposited at the same time, during four key intervals spanning the past 43,000 years.

This suggests the formation of each layer was determined mainly by shifts in environmental conditions throughout the Kimberley, rather than by the distinct conditions in each particular rock shelter.

The records held by these glazes over such a large time period – including the most recent ice age – means they could help us better understand the environmental changes that directly affected human habitation and adaptation in Australia.

Hypothetical example of how layered mineral coatings can be used to date engraved rock art in Kimberley rock shelters.
Pauline Heaney

Stories in stone

Research we published earlier this year shows how the subjects painted in early Kimberley rock art changed from mostly animals and plants around 17,000 years ago, to mostly decorated human figures about 12,000 years ago.

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This 17,500-year-old kangaroo in the Kimberley is Australia’s oldest Aboriginal rock painting

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Other researchers have discovered that during this 5,000-year period there were rapid rises in sea level, in particular around 14,500 years ago, as well as increased rainfall.

We interpret the change in rock art styles as a response to the social and cultural adaptations triggered by the changing climate and rising sea levels. Paintings of human figures with new technologies such as spear-throwers might show us how people adapted their hunting style to the changing environment and the availability of different types of food.

By dating the natural mineral coatings on the rock surfaces that acted as a canvas for this art, we can hopefully better understand the world in which these artists lived. Not only will this give us more certainty about the position of particular paintings within the overall Kimberley stylistic rock art sequence, but can also tell us about the environments experienced by First Nations people in the Kimberley.

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We thank the Balanggarra Aboriginal Corporation, the Centre for Accelerator Science at the Australian National Science and Technology Organisation, Rock Art Australia and Dunkeld Pastoral Co for their collaboration on this research._

Helen Green, Research Fellow, The University of Melbourne and Damien Finch, Research fellow, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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How indigenous expertise improves science: the curious case of shy lizards and deadly cane toads

The Balanggarra Rangers are land management representatives of the Balanggarra people, the indigenous traditional owners of the East Kimberley. (L-R) Wes Alberts, Bob Smith (coordinator) James ‘Birdy’ Birch, Isiah Smith, Quentin Gore.
The Kimberley Land Council, Author provided

Georgia Ward-Fear, University of Sydney and Rick Shine, University of Sydney

It’s a common refrain – western ecologists should work closely with indigenous peoples, who have a unique knowledge of the ecosystems in their traditional lands.

But the rhetoric is strong on passion and weak on evidence.

Now, a project in the remote Kimberley area of northwestern Australia provides hard evidence that collaborating with Indigenous rangers can change the outcome of science from failure to success.

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We’ve cracked the cane toad genome, and that could help put the brakes on its invasion

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Fighting a toxic invader

This research had a simple but ambitious aim: to develop new ways to save at-risk predators such as lizards and quolls from the devastating impacts of invasive cane toads.

Cane toads are invasive and highly toxic to Australia’s apex predators.
David Nelson

All across tropical Australia, the arrival of these gigantic alien toads has caused massive die-offs among meat-eating animals such as yellow-spotted monitors (large lizards in the varanid group) and quolls (meat-eating marsupials). Mistaking the new arrivals for edible frogs, animals that try to eat them are fatally poisoned by the toad’s powerful toxins.

Steep population declines in these predators ripple out through entire ecosystems.

But we can change that outcome. We expose predators to a small cane toad, big enough to make them ill but not to kill them. The predators learn fast, and ignore the larger (deadly) toads that arrive in their habitats a few weeks or months later. As a result, our trained predators survive, whereas their untrained siblings die.

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Conservation ‘on Country’

But it’s not easy science. The site is remote and the climate is harsh.

We and our collaborators, the Western Australian Department of Biodiversity, Conservation and Attractions, decided at the outset that we needed to work closely with the Indigenous Traditional Owners of the east Kimberley – the Balanggarra people.

So as we cruised across the floodplain on quad bikes looking for goannas, each team consisted of a scientist (university-educated, and experienced in wildlife research) and a Balanggarra Indigenous ranger.

Although our study species is huge – a male yellow-spotted monitor can grow to more than 1.7 metres in length and weigh more than 6kg – the animals are well-camouflaged and difficult to find.

Over an 18-month study, we caught and radio-tracked more than 80 monitors, taught some of them not to eat toads, and then watched with trepidation as the cane toad invasion arrived.

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Yes, you heard right: more cane toads really can help us fight cane toads

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Excitingly, the training worked. Half of our trained lizards were still alive by the end of the study, whereas all of the untrained lizards died soon after toads arrived.

That positive result has encouraged a consortium of scientists, government authorities, conservation groups, landowners and local businesses to implement aversion training on a massive scale (see www.canetoadcoalition.com), with support from the Australian Research Council.

A yellow-spotted monitor fitted with a radio transmitter in our study. This medium-sized male was trained and lived for the entirety of the study in high densities of cane toads.
Georgia Ward-Fear, University of Sydney

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Teaching reptiles to avoid cane toads earns top honour in PM’s science prizes

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Cross-cultural collaboration key to success

But there’s a twist to the tale, a vindication of our decision to make the project truly collaborative.

When we looked in detail at our data, we realised that the monitor lizards found by Indigenous rangers were different to those found by western scientists. The rangers found shyer lizards, often further away from us when sighted, motionless, and in heavy cover where they were very difficult to see.

Gregory Johnson, Balanggarra elder and ranger.
Georgia Ward-Fear

We don’t know how much the extraordinary ability of the rangers to spot those well-concealed lizards was due to genetics or experience – but there’s no doubt they were superb at finding lizards that the scientists simply didn’t notice.

And reflecting the distinctive “personalities” of those ranger-located lizards, they were the ones that benefited the most from aversion training. Taking a cautious approach to life, a nasty illness after eating a small toad was enough to make them swear off toads thereafter.

In contrast, most of the lizards found by scientists were bold creatures. They learned quickly, but when a potential meal hopped across the floodplain a few months later, the goanna seized it before recalling its previous experience. And even holding a toad briefly in the mouth can be fatal.

Comparisons of conditions under which lizards were initially sighted in the field by scientists and Indigenous rangers (a) proximity to lizards in metres (b) density of ground-cover vegetation (>30cm high) surrounding the lizard (c) intensity of light directly on lizard (light or shade) (d) whether the lizard was stationary or moving (i.e. walking or running). Sighting was considered more difficult if lizards were further away, in more dense vegetation, in shade, and stationary.
Georgia Ward-Fear, University of Sydney

As a result of the intersection between indigenous abilities and lizard personalities, the overall success of our project increased as a result of our multicultural team.

If we had just used the conventional model – university researchers doing all of the work, indigenous people asked for permission but playing only a minor role – our project could have failed, and the major conservation initiative currently underway may have died an early death.

So our study, now published in Conservation Letters, provides an unusual insight – backed up by evidence.

Moving beyond lip service, and genuinely involving Indigenous Traditional Owners in conservation research, can make all the difference in the world.

Georgia Ward-Fear (holding a yellow-spotted monitor) with Balanggarra Rangers Herbert and Wesley Alberts.
David Pearson, WA Department of Biodiversity, Conservation and Attractions

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This research was published in collaboration with James “Birdy” Birch and his team of Balanggarra rangers in the eastern Kimberley.

Georgia Ward-Fear, Post doctoral fellow and Conservation Ecologist , University of Sydney and Rick Shine, Professor in Evolutionary Biology, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Searching for the Nabarlek

Even the super-corals of Australia’s Kimberley are not immune to climate change

Verena Schoepf, University of Western Australia

Coral reefs around the world are in trouble because of climate change and other pressures such as overfishing, pollution and outbreaks of coral-eating predators. Currently, they are in the spotlight because a mass bleaching event on global scale has been declared – the third since records started in the 1980s.

As mass bleaching events become more common due to rising ocean temperatures, it is increasingly urgent to understand what makes corals resistant to heat stress and climate change.

Natural laboratories

Naturally extreme environments such as the Kimberley region in northwest Australia are ideal laboratories to study this question. My colleagues and I reveal in research published today in Scientific Reports that the highly fluctuating temperatures in these extreme environments boost the ability of coral to cope with heat stress – but they do not provide immunity to bleaching.

The Kimberley region is a fascinating place: largely unspoiled and abounding with coral reefs despite conditions that would be deadly to the majority of coral elsewhere on the planet. This is because the Kimberley has the largest tropical tides in the world, up to 10 metres!

As a consequence, intertidal coral communities often get exposed to air for several hours during low tide and also experience mid-day temperatures up to 37°C for short periods of time. In contrast, maximum summer temperatures on most coral reefs elsewhere rarely exceed 30°C.

Intertidal coral communities in the Kimberley exposed during low tide. Copyright: Steeve Comeau.

The “super-corals” living in the nearshore Kimberley are adapted to these extreme conditions and likely have not experienced any major bleaching events in the past according to the Bardi Jawi people, the Traditional Owners at our field site in Cygnet Bay. This made us wonder whether adaptation to such environmental extremes has made corals more resistant to bleaching and climate change – a compelling idea that we wanted to test.

Why corals bleach

Coral bleaching occurs when corals suffer from heat stress and expel the microscopic symbiotic algae that live inside their tissue. Since the algae not only give coral most of their colour but also the majority of their food energy, bleached corals are essentially starving and can die if water temperatures remain hot for too long.

Bleached but still alive staghorn coral. Copyright: XL Catlin Seaview Survey.
http://www.globalcoralbleaching.org/

We tested the heat tolerance of nearshore Kimberley corals in a tank experiment, where we simulated a bleaching event by heating the water in some of the tanks 2-3°C above the corals’ typical summer temperatures. Such temperatures are already encountered during marine heatwaves today and could become “normal” summer temperatures by the year 2100.

To our surprise, even the “super-corals” started to show signs of bleaching within only a few days – but some corals were more resistant than others.

Coral bleaching tank experiment at Cygnet Bay Pearl Farm. Copyright: Verena Schoepf.

Heat resistance

Corals from tide pools which regularly experience exposure to air, stagnant water, and temperature extremes coped with the hot water much better than corals from below the low-tide mark, where conditions are far more moderate. This shows that highly-variable, extreme temperature environments can boost the bleaching resistance of corals.

The microscopic symbiotic algae inside corals also influence how a coral reacts to heat stress. Although some types of algae can withstand hot water better than others, we found that all corals in our experiment harboured algae from a group that isn’t particularly known for its stress resistance. This confirmed the important role that the environment plays in determining coral resilience to climate-driven stresses.

Finally, corals occur in a myriad of growth forms, including branching, mounding, plating, massive and even encrusting types. In our study, branching staghorn corals bleached sooner than massive corals and many of them died, whereas all massive corals survived.

This type of bleaching pattern is typical for most coral reefs in the world. Unfortunately, the more heat-sensitive staghorn corals are the dominant corals on Indo-Pacific reefs, which is partly why mass bleaching events result in such wide-spread coral mortality.

Good and bad news for the future

Our results offer a mix of good and bad news for future coral reefs. Since extreme temperature environments boost the heat resistance of corals, they could potentially serve as temporary refuges from climate change. Corals in these environments could also recover faster from bleaching and thus potentially help to repopulate coral reefs that are hit harder.

The bad news is that even super-corals from extreme environments nevertheless remain vulnerable to severe heat stress events. As such events are becoming more frequent, it is unclear whether corals will be able to adapt fast enough to keep pace with global warming.

The current global bleaching event is a foretaste of what is to come. Repeated bleaching events have already led to significant coral deaths and reef decline in places such as the Persian/Arabian Gulf.

However, even when it comes to annual bleaching, some corals are more resistant than others and can recover quickly, as some of my past research has shown. And in the Kimberley, off-shore reefs recovered quickly after the first recorded global bleaching event in 1998 due to their isolated location.

While there is enough reason to be alarmed about the future of coral reefs, obituaries may be premature. Future coral reefs will likely be severely degraded, but there is hope that these cities under the sea will persist for many more decades.

Chances are that the super-corals from the Kimberley will be among the stalwart survivors.

Verena Schoepf, Research Associate, University of Western Australia

This article was originally published on The Conversation. Read the original article.

Australia: Western Australia – Great Kimberley Marine Park

The link below is to an article that reports on the new Great Kimberley Marine Park in Western Australia.

For more visit:
http://www.australiangeographic.com.au/journal/new-kimberley-marine-park-to-rival-gbr.htm

Video: Kimberley Region

Western Australia: Kimberley – Horizontal Falls Protected

The link below is to an article reporting on new marine parks and a national park recently announced for Western Australia, that will help protect Horizontal Falls in the Kimberley.

For more visit:
http://www.abc.net.au/news/2013-01-28/national-park-created-to-protect-horizontal-falls/4487354

Australia: Western Australia – Western Long-Beaked Echidna May Still Exist in the Kimberley

The link below is to an article reporting on the possible existence of what was thought to be an extinct Echidna in Western Australia.

For more visit:
http://www.australiangeographic.com.au/journal/locally-extinct-echidna-may-be-alive-in-wa.htm

Article & Photos: Western Australia – Kimberley Region

The link below is to an article (with photos) that investigates Western Australia’s Kimberley Region and in particular the Berkeley River.

For more visit:
http://www.australiangeographic.com.au/journal/kimberleys-berkeley-river-region.htm

Australia: Western Australia – Gouldian Finch

A new breeding population of the extremely rare Gouldian Finch has been found in the Kimberley region of Western Australia.

For More Visit:
http://au.news.yahoo.com/a/-/latest/12658787/rare-bird-find-in-wa-s-north-boosts-hopes/