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Sciences

Natural history - from animals to minerals, fossils to sea slugs. MV's scientists use the state's collections in important research.

Alpine frogs and chytrid fungus

Author
by Kate C
Publish date
17 January 2014
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Frogs were an important focus for the Alps Bioscan survey in Victoria's Alpine National Park in November last year. The deadly amphibian chytrid fungus, Batrachochytrium dendrobatidis, thrives in cool environments, meaning high-altitude frog populations are particularly susceptible.

Dr Katie Smith, Collection Manager of Vertebrates, led the frog-hunting team at the Alps and explained why this fungus is so insidious. "It's a major contributor to global amphibian decline. Lots of frogs worldwide are affected," she said. "It penetrates their skin and leads to death in some species and individuals, while some are able to survive it and act as carriers."

View this video with a transcript

The museum's frog team searched for frogs in several sites in the Alps and collected skin swabs from every frog found. The swabs will be tested for the presence of chytrid (pronounced 'kit-trid') as part of ongoing monitoring by researchers from the Arthur Rylah Institute for Environmental Research. "We need to know what populations have it and whether this leads to changes in those populations, such as whether there's lower species diversity in areas where chytrid fungus is present."

The chytrid fungus has a free-living stage called a zoospore and a reproductive stage called a zoosporangium. Zoospores can live several weeks in the water until they find a host frog to infect. Once settled, the zoosporangia cause the frog's skin to thicken and slough away. There are a few hypotheses as to how the chytrid fungus kills frogs. One hypothesis proposes that a frog with a heavy chytrid infestation can't maintain its salt balance. Sodium and potassium levels, essential for normal muscle and nerve function, drop significantly and the frog dies from cardiac arrest.

froglet A froglet found during the Alps Bioscan. Froglet species seem to have some resistance to chytrid fungus, and may act as carriers between water bodies.
Image: David Paul
Source: Museum Victoria
 

Researchers believe that the fungus arrived in Australia in the 1970s, and is linked to the sudden decline (and in some cases, extinction,) of several local species, including the Southern Gastric Brooding Frog and the Southern Corroborree Frog. There are a few theories about how it got here, but the most likely culprit is the international trade in African Clawed Frogs for use in pregnancy tests. In the 1930s it was discovered that injecting one of these frogs with the urine of a pregnant woman caused the animal to produce eggs. Hundreds of thousands of frogs were brought into Australia from Africa for this purpose and probably, with them, the chytrid fungus. While the fungus was first identified in 1998, retrospective examination of historical specimens found the earliest known chytrid infestation on an animal collected in 1938. This African Clawed Frog specimen, held by the South African Museum, supports the theory of African origin.

Once loose in a new environment, chytrid fungus can spread rapidly. "It can be spread by frogs – anything that moves through those water bodies, even other animals that visit those areas and researchers themselves," explained Katie. "You might walk into one site, jump in the car and accidentally transfer it to a healthy population."

You can help prevent the spread of chytrid fungus in a couple of ways. Firstly, says Katie, "never move a frog, tadpoles or eggs that you find in one area to another area, because you don't know which populations may have the chytrid fungus." Frogs are protected in Australia which means that you cannot legally catch, remove or relocate them; the threat of chytrid fungus is another good reason to leave them where they are. Frogs often hitchhike from Queensland in bunches of bananas, so if you find a stowaway in your supermarket, follow the instructions of the Victorian Frog Group and never release the frog into the wild.

Katie continued, "secondly, if you're moving between water bodies, wash your shoes really well and anything else you put in water." The Alps Bioscan teams bleached and scrubbed shoes and equipment between each aquatic field site, and Katie's frog team wore fresh surgical gloves when handling each frog.

The results from the survey and chytrid tests will be available later this year once the researchers have completed their analysis.

Links:

Ché Weldon, Louis H. du Preez, Alex D. Hyatt, Reinhold Muller,and Rick Speare. Origin of the Amphibian Chytrid FungusEmerg Infect Dis. 2004 December; 10(12): 2100–2105.

David Hunter, Rod Pietsch, Nick Clemann, Michael Scroggie, Gregory Hollis and Gerry Marantelli. Prevalence of the Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) in Populations of Two Frog Species in the Australian Alps. 

Alpine School interviews at Alps Bioscan

Author
by Priscilla
Publish date
7 January 2014
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Priscilla is a Program Coordinator for Life Sciences and works on education programs at Melbourne Museum.

In 1914 and 1915, scientists and field naturalists explored the Alpine region of Victoria. Nearly one hundred years later, we sent our museum's ornithologists, herpetologists, mammalogists, entomologists, palaeontologists, and others out into the field to explore, discover, and record the wildlife – alive and fossilised. This recent expedition in November last year, called the Alpine Bioscan, was a collaboration between Museum Victoria and Parks Victoria to perform a major wildlife census in the eastern region of Victoria’s Alpine National Park, with 100 experts taking part.

black and white photo of men on horses Men and horses during the survey of the Alpine area in 1914 and 1915.
Source: Museum Victoria
 

People with malasie trap Today’s scientists: Mel Mackenzie, MV’s Marine Invertebrate Collection Manager, and Parks Victoria staff inspecting a Malaise trap in the Alps. Malaise traps catch flying insects.
Source: Museum Victoria
 

We’ll never know exactly the thoughts and experiences of those early researchers in the black and white photographs – but to ensure that doesn’t happen again, we invited eight students from the Alpine School to become Bioscan Ambassadors. Their role was to interview our scientists, record it and share it. The response from the students was overwhelming; all 45 students in the school wanted to participate. The lucky eight had their names pulled from a hat.

So, on the afternoon of November 28th, I went with MV historian Rebecca Carland to the Alpine School to work with the students and their teacher Nicola. The students learned from Bec how to interview a scientist, what makes a good question, and how to plan and record an oral history to make an interview clip. When they learned that their clips may become a permanent part of the museum’s collection, two students nearly cried with happiness.

eight students at table The eight Bioscan Ambassadors, workshopping their ideas for interviewing the scientists.
Source: Museum Victoria
 

On day two of the project, the students and the scientists met at Omeo Memorial Hall. The students' training put them in good stead for the realities of filming in the field – dealing with difficulties like not being able to film outside due to the rain, bad acoustics, and even unflattering lighting. But, like pros – they pushed on, filming and questioning scientists through the challenges.

Four people around a computer Students editing their clip with assistance from Bec Carland, MV historian and Roger Fenwick, Manager Regional Operations, Parks Victoria.
Image: Heath Warwick
Source: Museum Victoria
 

The result was four great video interviews of Museum Victoria scientists which are now on the Making History channel on Vimeo. In another century, when people look back at the photographs of today’s scientists in the field and wonder who these people were, the students’ films will show them.

This project was supported by the Department of Education and Early Childhood Development’s Strategic Partnership Program.

Links:

Interview with Mel Mackenzie

Interview with Mark Norman

Interview with Rolf Schmidt

Interview with Ken Walker

Great White Sharks at IMAX

Author
by Kate C
Publish date
2 January 2014
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William Winram is a champion freediver and a passionate advocate for the protection of marine ecosystems. He uses his freediving abilities to help monitor shark populations, and he visited Melbourne Museum recently to talk about Great White Shark 3D, a new IMAX film that features him doing exactly that.

William Winram William Winram
Image: Michele Monico
Source: William Winram
 

Most divers use SCUBA breathing apparatus, but freedivers like William reach similar depths while holding their breath. This is a very different way to interact with sharks, as William explains. "When you hold your breath, your heart rate reflexively slows. There's a whole shift, physiologically, that doesn't happen in SCUBA diving." He believes that freediving makes him less intrusive, because "with SCUBA, you're entering as an alien. You're taking apparatus from the surface world, so right away your relationship is totally different." Freedivers can also move more freely in the water column, and don't generate noisy bubbles. "For a lot of species, bubbles are a sign of aggression," says William.  "If a male sea lion is getting upset, he blows bubbles and barks at us. That's how he shows his dissatisfaction."

William Winram preparing William Winram preparing for his world record freedive attempt in September 2013, Egypt.
Image: Alice C. Attaneo
Source: William Winram
 

William describes the sharks he encounters – Great White Sharks, Hammerheads, Tiger Sharks and others – as "shy, curious and cautious predators", quite unlike the killing machines of media and cinema. "Sharks are not obsessed with or addicted to killing, but they do need to eat. They know that we're not their normal diet, so they don't typically eat us." His calm, respectful approach to the world's largest predatory fishes means he is able to tag sharks harmlessly, unlike some other tagging techniques that often kill the animal.

"It's like you're walking down the hallway and I hit you in the rear end with a hypodermic needle. Afterwards you have a little bruise but you're fine." He and his colleagues aim for the thick muscle at the base of the shark's dorsal fin and use a specially modified spearfishing gun. All that's left is a small dart and tag – and these tags are allowing scientists to learn about the feeding behaviour and global movement of sharks. Tagging has also shown that Great White Sharks head for a mysterious area in the middle of the Pacific known as the Shark Café. No one is quite sure what the sharks do there, but it is clear that the animals have complex annual migratory patterns.

He sees Great White 3D as an opportunity to address the misunderstandings about sharks and encourage interest in their conservation. "We like to demonise sharks and we like to glorify other creatures, and all of it is false. People want to have this fantasy, an unreal world where things are either beautiful or ugly, nice or not. Sharks are easy to exploit because they're not cute and cuddly," he says. 

William Winram freediving William Winram freediving with a Great White Shark in Isla Guadalupe, Mexico.
Source: Still from Great White Shark 3D
 

Like all apex predators, Great White Sharks are found in relatively low numbers, yet they are vital in moderating populations of other species. Ecosystems suffer when they lose their apex predators, so the decline in sharks from human activities worries William very much. "We need to understand that we are part of an ecosystem. 50 per cent of the oxygen that we breathe comes from the sea.  At a certain point, if you kill them all off, the sea is done. It's time to respect your position and your role in your ecosystem."

Great White Shark 3D is now playing at IMAX Melbourne Museum.

Links: 

William Winram's website

ABC Science: Great whites hang out in 'shark cafe'

'In deep water' by Tim Winton for the Sydney Morning Herald

Burrowing bees

Author
by Kate C
Publish date
18 December 2013
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No biologist worth their salt will stumble across a burrow in the ground without having a good stickybeak. And museum biologists are definitely worth their salt*.

So when the Alpine National Park Bioscan team found several hundred small burrows in one spot, they couldn't just wonder if they were made by crayfish or perhaps mole crickets. This hypothesis needed testing. Colin from Live Exhibits got to digging.

hut in the Alps Burrows in the foreground and Davies Plain Hut in the background.
Source: Museum Victoria
 

He stuck a blade of grass down the burrow and used a spoon to carefully dig around it. About 30 or 40 cm down he found, not a cray or cricket, but a little bee. It was no coincidence; a second excavation turned up another bee in the next burrow.

Colin digging holes Colin digging up burrows with a spoon.
Source: Museum Victoria
 

The bees belong to the subfamily Halictinae, which happens to be the speciality of museum entomologist and bioscan participant Dr Ken Walker. He collects most of his study specimens as they are out foraging and rarely sees the burrows. And he'd never seen burrows in such high density –about 400 in one small grassy area.

Ken explained that the bees belonging to the genus Lasioglossum and subgenus Parasphecodes. "Lasioglossum is one of the largest genera in Australia, doing most of the work of pollinating." These burrows are where the female bees brood the next generation.

Halictine bee The halictine bee responsible for the burrows.
Image: David Paul
Source: Museum Victoria
 

"They're a semi-social bee," said Ken. "In a single nest there can be six to ten females, which are all queens. They all lay their own eggs, and they all help excavate that main tunnel but each one of them then makes a lateral tunnel by themselves. At the end they build a group of cells each lined with saliva, and they put in a pollen ball mixed with a little bit of nectar, and they lay an egg and close the whole thing up."

But that's not the end of the story, because the bee larva isn't alone in the cell. Looking closely, Ken spotted a number of large mites on the backs of the bees. The mites are harmless to the bee since they're a non-feeding, migratory (or hypopial) life stage, waiting patiently for the bee to finish stocking the brood cell with pollen.

Halictine bee with mite The red arrow shows the location of a hitch-hiking mite on this bee.
Image: Ken Walker
Source: Museum Victoria

Mite on a bee Detail of a mite on the back of a bee.
Image: Ken Walker
Source: Museum Victoria
 

Said Ken, "just before the bee closes up the cell, she turns around and brushes one or two mites off, which then develop to the feeding and sexual stages." The mites act like little housekeepers, eating any mould or fungus that attacks the pollen ball and thus keeping it fresh for the developing bee. When the new adult bee is ready to emerge, the mites' own young clamber aboard and travel on to the next burrow. "It's a wonderful relationship there."

Halictine bee Dorsal view of the burrowing semi-social bee.
Image: David Paul
Source: Museum Victoria
 

So there you have it – nosy biologists reveal an underground community of fascinating little animals, and Parks Victoria rangers have an interesting reason to recommend that tents be pitched away from the field of muddy burrows.

*Humans contain about 0.4% salt by weight. So a 70kg museum biologist, say, contains about 280g salt**. That much table salt costs about a dollar from a supermarket. If instead we say they're worth their weight in gold, according to today's price, and the Dynamic Earth scale, that puts our 70kg biologist at $3,112,900. The real value is probably somewhere in the middle.

**Except marine biologists. They're a bit saltier.

Links:

ABC Bush Telegraph: Hive of activity reveals all in alpine bioscan

The Age: Critter census reaps bonanza for researchers

MV Blog: Alpine Bioscan

A Christmas star for 2013

Author
by Tanya
Publish date
13 December 2013
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Just in time for Christmas, a new star has appeared in our southern sky!

Nova Centauri 2013 is the brightest nova to be seen since 1999. It is about as bright as the fifth star in the Southern Cross and is very easy to spot from Melbourne, and across Australia in general. It sits right next to Beta Centauri, one of the famous two pointer stars that leads the way to the Southern Cross.

Nova Cen 2013 from ESO This photograph was taken from La Silla Observatory in the Chilean Atacama Desert on the morning of 9 December 2013.
Image: Yuri Beletsky
Source: ESO
 

The nova appears just to the left of Beta Centauri, the bluer and higher of the two bright stars in the lower-right part of the image. The Southern Cross and the dark Coal Sack Nebula are also captured near the top of the image.

The nova was discovered on 2 December by John Seach from New South Wales. It is a 'classical nova' and is caused by a dead white dwarf star having a brief, but intense new-lease on life. White dwarfs are stellar embers, where nuclear fusion (the fire that keeps a star shining) has ended. However, this white dwarf has a close companion star. If enough gas from the companion falls onto the white dwarf it triggers a brief explosion on the star's surface.

The star undergoes an extreme burst of brightness. But unlike a supernova, the white dwarf remains intact and lives to tell the tale.

What better reason is there to slip away from the Christmas madness and spend a quiet moment or two, under the stars.

Links:

Ideas about the 'real' Christmas star from Phil Plait's Bad Astronomy blog

ESO Science Outreach Network - Australia

Goodbye, Comet ISON

Author
by Tanya
Publish date
29 November 2013
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Comet ISON has not survived its close encounter with the Sun. Time-lapse from NASA's Solar and Heliospheric Observatory shows the comet's head fading away, leaving only a dusty tail. A few hours later something - perhaps a small fragment or stream of debris - emerges from behind the Sun. Updates are continually being posted on http://spaceweather.com/.


Final views of Comet ISON from NASA's Solar and Heliospheric Observatory (SOHO) satellite, taken on the morning 29 November (AEDT).
Source: NASA/SOHO consortium


The environment of the Sun is a tough place for comets. ISON has been bombarded by heat and radiation, buffeted by the solar wind and also stretched by the Sun's gravity (think of a micro-version of a black hole's spaghettification). It's a love-hate relationship because comets need the Sun if they are to produce an impressive tail and put on a good show.

Comet ISON was discovered in September last year from Russia, by astronomers Vitali Nevski and Artyom Novichonok. Two things made this comet special - it would be the first time the comet would travel in towards the Sun from the outer solar system but, what's more, it would be a sungrazer, coming within 1.6 million kilometres of our star.

Northern hemisphere observers have been particularly interested, because if the comet had survived its passage, they would've had the best seats. From here in the south, the comet would not have been visible, unless it had erupted brightly enough to be seen during the day.

Comet ISON - 15 November Comet ISON photographed on 15 November from the UK. Amateur astrophotographer Damian Peach used a 17-inch telescope for 12 minutes of combined exposures.
Image: Damian Peach
Source: Damian Peach


NASA's Solar TErrestrial RElations Observatory (STEREO) captured the solar wind buffeting Comet ISON and Comet Encke on 21 November.
Image: Karl Battams
Source: NASA, STEREO, CIOC

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