Our Changing World
Thursday 28 August 2014, with Alison Ballance, Ruth Beran & Veronika Meduna
On This Programme
- Sea Lions As Food Web Ambassadors
- Climate Lessons From Antarctica
- From Party Drug to Anti-Addiction Treatment
- Ultrasound Device to Help Visually-Impaired Navigate
- Melting Ice, Rising Sea
- OCW Mystery Sound 9
Sea Lions As Food Web Ambassadors
If a marine biologist can shave enough sea lions, she’s hopeful the fur she collects will give her insights into marine food webs and how they’ve changed over time.
Lucy Jack, from the Department of Marine Science at the University of Otago is using New Zealand sea lions and fur seals as ‘food web ambassadors’. The fur samples she collects from animals in Otago, Southland, Stewart Island and the Auckland islands will give her an insight into the diet of present-day animals, while collagen from sub-fossil bones from Maori middens will show what their diet was like before Europeans arrived. Archaeologists from the University of Otago have also been able to identify a few bones that pre-date Maori arrival in New Zealand.
Lucy tells Alison Ballance that she is using stable isotope analysis to identify whether the fur seals and sea lions, which are apex predators, at the top of the food chain, are eating food from a kelp-based or coastal food web, or from a phytoplankton-based open ocean food web.
“By finding out what trophic level they’re feeding at I can find out how tall the food web is,” says Lucy. “That’s important because natural food webs tend to be really complicated, and really tall with lots of links, which makes them really stable. Human impacts such as overfishing or sediment run-off and other kinds of pollution lead to loss of species, which leads to simpler food webs with fewer trophic levels which are generally less stable.
Lucy hopes the fur seals and sea lion data will show how food webs have changed over time, and that this information will help guide the restoration of fully functioning marine ecosystems.
To collect a small amount of fur from sea lions with the minimal amount of disturbance Lucy created a special piece of equipment, which consists of a cheap razor (one without a moisturising strip) clamped to a long broom handle. She has a special permit from the Department of Conservation which authorises her to approach animals on the beach, and after allowing the animal to sniff the razor she rubs the razor against its back or shoulder to snag a few hairs in the blades. Most sea lions happily ignore the razor, while a few enthusiastic ones actively rub against it as if they are enjoying a good scratch.
The research, which is still in an early phase, is part of a Marsden-funded project called ‘You can't go home again: forensic evidence for changes in ecosystem function following mainland extinction of pinniped.’
A story about research on the small but growing population of New Zealand sea lions on the Otago Peninsula has featured previously on Our Changing World.
NZ Sea Lions on the Otago Peninsula ( 14 min 24 sec )
In another Our Changing World story we heard about the Taking Stock project, and how archaeology was able to show how populations of New Zealand sea lions and fish have declined since pre-human times to the present day.
Early Maori Marine Diet ( 16 min 45 sec )
More University of Otago research has showed that until recently another species of sea lion inhabited mainland New Zealand, and has been replaced by the New Zealand sea lion.
Extinct Sealion Species ( 13 min 12 sec )
What Sea Lions Can tell us About Marine Food Webs
Climate Lessons From Antarctica
The world is already experiencing rising sea levels because the oceans are expanding as they warm up. This thermal expansion has so far been the biggest contributor to sea-level rise, but Antarctic scientists predict that melting ice sheets will become the driving force sooner than we thought.
Antarctica is in the spotlight this week as New Zealand hosts the Scientific Committee on Antarctic Research (SCAR) open science conference for the first time, together with several other high-level conferences and public events taking place under the banner of World Science Week New Zealand.
The SCAR meeting brought together almost 1000 top researchers to discuss the changing face of Antarctica and the impact on global climate and biological diversity.
One of the speakers is Rob DeConto, a geoscientist and climate modeller at the University of Massachusetts Amherst, who has focused his research on the dynamics and sensitivity of Antarctica’s ice sheets and their contribution to sea-level rise.
The Antarctic ice sheets hold about 75 per cent of the world’s freshwater, frozen in a delicate equilibrium, and if they were to melt, sea levels would rise by almost 60 metres. Earlier this year, research based on four decades of satellite observations showed that some major outlet glaciers in West Antarctica are melting and have already reached a point of no return (you can read our story and listen to our interviews here). NASA warned that there was nothing to stop the complete retreat of these glaciers, which in turn would speed up the flow of ice from the West Antarctic Ice Sheet.
Rob DeConto tells Veronika Meduna that the latest climate models confirm the melting of West Antarctic glaciers and predict that Antarctica’s ice sheets could contribute more than a meter of sea-level rise by the end of the century – significantly more than the projections in the latest report by the Intergovernmental Panel on Climate Change.
A lot of the Antarctic ice sheet is sitting on bedrock that is well below sea level, in some places more than a kilometre below sea level. The West Antarctic Ice Sheet is essentially just bathed in ocean water.”
Parts of Antarctica’s ice sheet are grounded below sea level. As the ice sheets themselves flow out into the ocean, they form floating slabs of ice called ice shelves, and Rob DeConto says that as the oceans continue to warm, these ice shelves will thin and lose some of the buttressing effect they have on the ice further inland.
The latest climate models Rob has developed use data from present-day observations as well information from the geological record. Two past periods of particular interest are the Pliocene, from about three to five million years ago, and the Last Interglacial, about 125,000 years ago.
During the Pliocene, carbon dioxide levels in the atmosphere were about the same as we have today, about 400ppm, but temperatures were 2-3ºC warmer than today. “Today’s global climate hasn’t caught up with the level of CO2 that we already have in the atmosphere,” says Rob DeConto.
During the Last Interglacial period, sea levels were five to nine metres higher, but CO2 was only about 280ppm, with temperatures similar to those today.
For both periods, there are good geological records showing how much higher the sea was, including the Wanganui Basin record which we featured recently on Our Changing World.
Drilling Into A Warmer Past ( 18 min 29 sec )
Rob DeConto says the latest models are now, for the first time, able to reproduce the changes in sea level during these past periods, which makes them robust tools for projecting into the future. They show more than a metre of sea level rise coming from Antarctica alone by 2100, and up to 10 metres by 2500, depending on what measures are taken over the next decade to reduce greenhouse gas emissions. However, changes in sea level are not uniform across the globe, and the biggest impact of increased melting in Antarctica will be felt in the Northern Hemisphere.
Rob DeConto is staying on in New Zealand to present the S.T. Lee lecture in Wellington on Wednesday 3 September and another talk in Dunedin next week.
He also took part in a public debate about Antarctica's role in future sea-level rise during World Science Week, together with the director of Victoria University's Antarctic Research Centre, Tim Naish, University of Bristol's Jonathan Bamber and CSIRO oceanographer Steve Rintoul, chaired by Gateway Antarctica director Bryan Storey.
Melting Ice, Rising Sea ( 1h 28 min 12 sec )
Climate Lessons from Antarctica
From Party Drug to Anti-Addiction Treatment
Research on a hallucinogenic mint plant that is used as a party drug may lead to new, improved anti-addiction treatments, according to neuroscientist Bronwyn Kivell from Victoria University of Wellington.
“All drugs of abuse activate the dopamine reward pathway in the brain,” says Bronwyn, “And that’s the path I’m focusing on in my research - how different drugs of abuse, from tobacco and methamphetamine to cocaine, activate these pathways and what we can do to stop this reward process.”
Bronwyn’s research focuses on a protein called the kappa opioid receptor, and she told Alison Ballance that it has a method of action which is ‘almost opposite’ to drugs of abuse.
“It’s been known to have anti-addiction properties and it’s the body’s natural way of fighting against the drugs of abuse activating this pathway,” says Bronwyn. “It’s almost like a punishment system the body has, and if we can activate that system we can possibly reverse the rewarding effects of some of these drugs of abuse.”
Researchers in Bronwyn’s lab are screening various compounds that have been developed by medicinal chemist Thomas Prisinzano from the University of Kansas in the United States. The work is focused on the plant Salvia divinorum. Also known as Mexican tripping weed, it is a powerful hallucinogen that has been used by Mexican Indians for hundreds of years. The screening carried out in Bronwyn’s lab is initially done with cells, and promising compounds may then be tested with animal models.
The work involves identifying the cellular mechanism of action of the various compounds and coming up with a potential side-effect profile. Side effects, which include dysphoria (a feeling of unease), nausea and depression, along with a short period of activity, are the main reason to date that no compounds have made it to pre-clinical trials, but Bronwyn is hopeful that they have identified at least one compound with high potential that is long-lasting and appears to have no side effects.
Bronwyn suggests that in the future it may be possible to add a kappa opiod-based compound to prescription pain medication to help avoid the addiction that is a side-effect of their use.
Ultrasound Device to Help Visually-Impaired Navigate
Like a torch, a device developed by Auckland researchers can illuminate the surrounding environment.
But instead of using light, this device uses sound.
Specifically, it uses ultrasound.
“A signal is sent out at ultrasound, through a transmitter that the person can hold in their hand. Reflections from the environment come back to the individual and can be picked up with receivers,” says Claire Davies, a senior lecturer at the University of Auckland. “Those receivers can actually convert the sound into an audible range signal, so users can actually hear the obstacles around them.”
It’s very similar to echolocation, a system used by animals like dolphins and bats, where they navigate by making clicks to hear sound reflecting off objects.
In this electronic device, the Doppler effect is used to translate relative movement between the user and a reflected obstacle into sound.
“It literally makes your surroundings sound as though they’re all making noise, but only if they’re moving relative to you,” says Shane Pinder from Defiant Engineering, the co-inventor of the device.
The device is designed for visually-impaired people who may use a cane or a guide dog, but would like additional information about objects that are above waist height.
“The sound that is emitted by this is at a frequency higher than that which guide dogs can hear. So we never find that we have any problems in an environment where a guide dog is used,” says Claire.
Ruth Beran got to trial an early prototype, and could hear the whooshing sound made by moving objects in the environment.
“The faster it’s moving, the higher the frequency -- the higher the pitch of the sound that it’s making. The closer it is to you, or the larger it is, the louder it is,” says Shane.
Ultimately, the goal is to make a device about the size of a 9 volt battery or a hand held mp3 player with a transmitter at the end, and earbuds which have ultrasonic microphones embedded on the outside to enable the sound to come into the ears.
Another aim is that the ambient sound would also come through the headphones, with the sound of the device superimposed on that.
“The idea is that it acts as a background noise or an ambient noise behind the person so it doesn’t interfere with other senses that they’re trying to listen to and so they are able to hear other obstacles in their environment,” says Claire.
And since the device uses sound, it can work just as well in the dark as it can in the light.
“We’re constantly looking for other ways that this might be useful to people, not just people who are visually-impaired,” says Shane.
So someone using a standard mp3 player or smart phone in the future, may be able to navigate in the dark using ultrasound, without the need to turn on a torch.
Melting Ice, Rising Sea
A discussion about the role of Antarctica's ice sheets in future sea-level rise, recorded during World Science Week New Zealand
OCW Mystery Sound 9
The Our Changing World opening theme is made up of 17 sounds that appeared on the show during 2012 and 2013. The 9th mystery sound is a titanium knife dropping, from a story about ion beam implantation.
Ion Beam Implantation ( 12 min 39 sec )
Coming Up – Thursday 4 September 2014
We play the Ora and Possum Stomp online games, which are based on real-life possum control research, we hear how wine waste could be turned into wound dressings, and we look inside a laser developed in New Zealand that uses fibre optic cables.