A weekly programme featuring a mix of sound-rich stories about science, the environment and medical research, recorded around New Zealand in laboratories and in the field. Our Changing World is broadcast nationwide on Thursday nights on Radio New Zealand National, during Nights with Bryan Crump. It is preceded in this recording by a news and sports bulletin, and weather forecast. In today's programme:
21:06
Medical Maggots for Wound Healing
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Maggots are used by hospitals and veterinary clinics to treat chronic ulcers and wounds, often as a last resort, and are bred in an insectary in Upper Hutt
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By Ruth Beran
For Neville Keen, the decision to use medicinal maggots was the right one.
I’d do it again tomorrow,” says Neville. “Being a diabetic you haven’t got many alternatives. I’m pleased I done that because I’ve still got my foot. I didn’t end up with gangrene.
Neville had a diabetic ulcer on the side of his heel which was treated with maggots four times. The maggots were encapsulated on the wound with a dressing for up to 72 hours.
“Larvae therapy is cheap, it’s quick, it’s effective, and it doesn’t harm good tissue because they only work on dead tissue. It’s non-invasive and it’s very safe practice,” says Judy Geary, Clinical Manager, District Nursing Services at Gore Hospital where maggots have been used over the past three years to treat 20 to 30 people. It can also be faster than some other options like surgical debridement which uses tools like scalpels.
The maggots work by debriding or cleaning the wound with an enzyme they exude, they also disinfect the wound, and their mouth hooks stimulate and rough up the wound bed which encourages the healing process.
“They’ve got chitinous, quite hard little mouth parts so when these are moving across the surface of the skin, they’re helping to create some blood flow and that also helps with the re-granulation of tissue,” says entomologist Dallas Bishop who breeds the medicinal maggots in her insectary in Upper Hutt near Wellington.
She breeds European green blowfly (Lucilia sericata) and each female fly is capable of laying 200 eggs in an egg batch. The flies’ wire cages, are wrapped with cheesecloth, and Dallas will put a piece of liver into the cage overnight and then collect and process the eggs laid on it.
In order to use them for medicinal purposes, the eggs are put in a solution of 50% bleach for three minutes, which helps the eggs separate.
They are then transferred into a solution of 2.5% formalin for three minutes which sterilises the surface of the eggs.
The eggs are put onto commercially supplied blood agar plates overnight, and will normally hatch within 18 to 24 hours. Dallas will then put 30 to 50 hatched larvae onto transportation media in 50ml sterile plastic containers. Holes are put into the lid of the containers which is covered with a sterile, breathable dressing. At this point the larvae are only about 1 to 2mm long. These containers are couriered to hospitals and veterinary clinics (where they are used mainly on horses) around the country.
The treatment is often used as a last resort, and patients are given some pain relief for the irritation that the larvae cause on the wound as they move over exposed nerve endings. “It’s certainly not an invasive procedure, there’s no scalpels involved,” says Dallas.
When asked why the treatment isn’t being used more commonly, district nurse Sonia Richardson says: “I think it’s just being able to think outside the square and accept a treatment that’s an old treatment but new I suppose, just to progress those wounds.”
Dallas says she would used the treatment herself:
If it was me and I didn’t have any other options, yeah I think it would be a good treatment, I’d certainly give it a go.
Topics: science, health
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Tags: medical, medicinal, maggots, treatment, ulcers, wounds, flies
Duration: 25'17"
21:33
Orokonui - Dunedin's Ecosanctuary
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The vision of the Orokonui Ecosanctuary is to recreate Otago coastal forest to the way it was before humans arrived in New Zealand
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By Alison Ballance
Places like Orokonui Ecosanctuary are just a beacon of hope – for humanity and for biodiversity. It’s the next best thing to an offshore island, but we’re only 15 kilometres from central Dunedin, so it makes wildlife more accessible to the general public.
Orokonui Ecosanctuary conservation manager Elton Smith
“The original idea was to set up a large aviary, because people were concerned about the imminent demise of rare bird species in New Zealand,” says Orokonui Ecosanctuary general manager Chris Baillie. “And that idea changed over time to create a whole functioning ecosystem for all the species, right through plants, invertebrates, birds and reptiles.”
Orokonui Ecosanctuary sits on the hill above Blueskin Bay, just north of Dunedin. It has been the only fenced sanctuary in the South Island, and is the only place in the South Island at the moment where tuatara and South Island saddleback are found.
The tuatara and saddlebacks are just two of the eight species that have been reintroduced so far in an effort to recreate a fully functioning forest ecosystem, that also includes a wetland and open grassy areas for the resident takahe.
“The goal is to recreate a piece of coastal Otago forest to what it was, as near as possible, before humans arrived. And clearly we can’t release the [extinct] moa – but maybe we can release some emu or ostrich,” says Elton, laughingly, “There’s some missing components that we’ll never get back, but there are many components that we can – and have – brought back.
In 2005 the Otago Natural History Trust began fund-raising to build the 8.7 kilometre predator-proof fence, which was completed in 2007. The sustainable visitor centre was completed in 2009, when the sanctuary was officially opened.
Chris describes the fence as the ‘cornerstone’ of the project; “it’s like a friend” says conservation manager Elton Smith. The fence encloses 307 hectares, from which all introduced predators and herbivores have been removed. The mammals included rats, mice, possums, hares, feral goats and possums, and were removed through a combination of hunting, aerial application of the toxin brodifacoum and trapping to remove the last remaining animals.
But even a predator-proof fence has its limitations. Animals can – and sometimes do – get past the fence into the sanctuary. Usually it’s a rat or a mouse, but earlier this year two stoats managed to get inside the sanctuary. The young female and an adult male were caught two weeks apart in the same trap, and although Elton never managed to find the place they got in, he is happy that they were promptly caught, and subsequent checking with a trained predator dog has failed to find any sign of further animals.
“The nasty C word around here is complacency,” says Elton. “You’ve just got to keep being vigilant. And you can never stop being vigilant, because if we walked away from this fence for six months we’d be back at square one. The place would be over-run with predators.”
Orokonui Ecosanctuary employs a small number of staff, but relies on its volunteers, who collectively put in more than 12,000 hours of work each year, valued at about a quarter of a million dollars. They also employ an educator and work with local schools, and the students who visit the sanctuary on a school trip are encouraged to share their experience with their family and bring them back for a visit.
Kaka were the first native species to be reintroduced to the sanctuary. A small breeding population of the rare kiwi the Haast tokeaka has been established, and the sanctuary has just become a crèche facility for young Haast tokeka, after their hatching in captivity, until they are large enough to be considered ‘stoat-proof’ and can be released back in the wild.
Tuatara have successfully bred for the first time on the mainland South Island for more than a hundred years, with the first young tuatara hatching earlier this year after a longer than usual incubation, lasting two winters, due to the cooler temperatures experienced in Otago. The tuatara at Orokonui have featured in a previous Our Changing World story.
South Island robins and South Island saddlebacks have both been successfully established in the sanctuary, following the advice and leadership of the late Ian Jamieson, an expert in conservation genetics at the University of Otago.
Elton is excited that visitors to the sanctuary are finally able to encounter the robins “They’ve finally moved up to the public walking tracks. It’s taken five years but finally people are able to see the robins – because they’ve always been down in the very north block, where there are no public tracks.”
Even though coastal Otago is outside their usual geographic range a small population of New Zealand’s largest lizard, the Otago skink, resides in a small enclosure near the visitor centre, where a stack of schist rocks has been placed to create the thermal environment filled with hiding places that the lizards require. There are also plans to establish a breeding population of another rare large skink, the grand skink.
“I’ve had the privilege to be here since day one”, says Elton. “And it’s been quite amazing. And the thousands – tens of thousands – of hours of hard work that staff and volunteers have put into this project. A lot of hard work. But it’s all been worth it.”
Topics: environment
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Tags: conservation, sanctuary, nature reserve, native birds, reptiles, Otago skinks, tuatara, predator-free New Zealand, predator-proof fence
Duration: 15'19"
21:34
Orokonui - Dunedin's Ecosanctuary
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The vision of the Orokonui Ecosanctuary is to recreate Otago coastal forest to the way it was before humans arrived in New Zealand ]tags] conservation, sanctuary, nature reserve, native birds, reptiles, Otago skinks, tuatara, predator-free New Zealand, predator-proof fence
Topics: environment
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Duration: 15'19"
21:46
The Long Journey to Aotearoa
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Archaeologist Atholl Anderson explains why he thinks that the first people to make landfall in New Zealand were exiles escaping from conflict in their homelands
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By Veronika Meduna
On archaeological grounds it’s very hard to say that this was a normal process of colonisation – that’s if you think of normal being that somebody goes out and explores, finds something, comes back and tells people, and then a large number of people decide to move to that place.
Atholl Anderson
The story of New Zealand's first colonisation is one of double-hulled canoes making return trips between Polynesia and the newly discovered Aotearoa, but new evidence about climate conditions at the time challenges this narrative, suggesting instead that the first people to make landfall in New Zealand were exiles escaping from conflict in their homelands.
Atholl Anderson is an archaeologist at the Australian National University, with a special interest in ocean navigation, maritime technology and the settlement of islands. Over the past few years, his focus has been on producing a comprehensive history of humanity’s last great migration across the Pacific Ocean and, ultimately, the settlement of New Zealand.
This work has taken shape as his contribution to Tangata Whenua: An Illustrated History, published by Bridget Williams Books and co-authored with Aroha Harris and the late Dame Judith Binney.
In the book chapters dealing with Polynesian origins and their migration path across the Pacific, he draws on the latest findings in genetics, linguistics and archaeology, as well as his own recent collaboration with palaeo-climate scientists, to conclude that the first colonists may not have arrived in New Zealand as a result of deliberate exploration, but were more likely fleeing from their homelands during a period of conflict.
From the linguistics and the nature of Māori cultural life – by that I mean things like social organisation, economic customs, or the ways in which people hunted and fished and planted – we can say that they certainly came from central eastern Polynesia.
“Whether that was Tahiti, the Cook islands or the austral islands is very hard to say, and indeed it might be all three of them because the genetic evidence we had recently of the genetic variety within the Māori population suggests that it was a fairly large colonising population … several hundred each of males and females, which in turn implies a number of canoes, very probably more than the traditional seven, and therefore they may have come from different islands."
He says there is no evidence that there was a period of exploration preceding the colonisation. If it had, archaeologist could expect to find traces left behind by people who returned to East Polynesia.
The evidence is of a relatively large population reaching New Zealand and not going back.
Atholl Anderson says that archaeology, genetics and linguistics have combined to map a more detailed route across the Pacific, beginning with the earliest Polynesian ancestors leaving south China about 5000 years ago. They spoke an Austronesian language, and traveled via Taiwan and Indonesia.
"We’re seeing the funneling of people and commodities, commensal and domestic plants and animals, from a wider catchment in south-east Asia, which includes Taiwan, but then they funnel down into an area along the islands to the north of New Guinea, and out down through the big islands east of New Guinea - the Solomons, New Caledonia, Vanuatu, Fiji, Tonga and Samoa – and it’s in those latter islands where we find the actual origins of Polynesian culture."
The next leg of the voyage took people into central East Polynesia, and then from there to the margins - the Polynesian triangle of Hawaii, Rapanui/Easter Island and Aotearoa/New Zealand. Atholl Anderson says it is this last part of the journey that was marked by growing conflict.
Traditional stories tell of a time of strive, on inter-lineage dispute, raiding of gardens and disagreements over access to resources ... and as a result of that period of skirmishing and warfare, some groups ... were effectively compelled to leave. There’s nothing in the traditions that says that they were told to go anywhere, it just says that they left.
The only way to leave was to go to sea, and this is where Atholl Anderson’s most recent work on the ocean climate conditions at the time of settlement adds a new element to the story. By analysing the ocean temperature record, he and his collaborators found that there was a period, corresponding with the time of colonisation, when high-pressure systems built up slightly to the east of New Zealand and brought winds that blew from north or north-east, acting “almost like a conveyor belt from the Cook Islands or Tahiti for a down-wind vessel”.
Then the wind patterns reversed back to persistent westerlies. His argument is that the maritime technology available to Polynesians at the time – during the 13th and 14th centuries – was limited to the double spritsail, a V-shaped sail with spars on each side, which can only sail with the wind. This is the only sail recorded in New Zealand before the 18th century.
Do these new findings take anything away from the idea that early Polynesian explorers were exceptionally skilled navigators?
“Not at all,” says Atholl Anderson.
“They had very good navigational skills, not any better than anybody else but certainly as good as anybody else. They were able to tell which latitude they were by using zenith stars and they could work out longitude by dead reckoning, that is to say by estimating their speed and direction where they were going.
“But it doesn’t take anything away from the sheer adventurousness and courage that was involved. If anything it adds to it because these people knew the limitations of their own craft. It took not just organisation and navigational ability, but a huge amount of courage, albeit under duress, probably.”
Topics: science, history, te ao Māori
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Tags: Polynesian migration, Māori origins, Polynesian origins
Duration: 13'19"