AN expert on Sydney Harbour’s marine life has taken out a new award from the Australian Academy of Science.
University of NSW marine ecology professor Emma Johnston, inaugural winner of the Australian Academy of Science's Nancy Millis Medal for Women in Science. Photo: Supplied
The academy has marked International Women’s Day today by presenting its inaugural Nancy Millis Medal for Women in Science to University of NSW marine ecologist Emma Johnston.
The award is for early-and mid-career women scientists who have established independent research programs and demonstrated exceptional leadership in any branch of the natural sciences.
Professor Johnston is a faculty member at UNSW’s School of Biological, Earth and Environmental Sciences. She also heads the Sydney Harbour Research Program at the Sydney Institute of Marine Science, a collaboration of universities and government agencies.
The five-year project aims to help inform the management of the harbour’s natural and economic resources. Professor Johnston said the harbour was one of the most biologically rich in the world.
“Below the surface we find extensive kelp forests, sweeping seagrass meadows, rocky reefs and vibrant sponge gardens all teeming with life. (But) humans have used oceans for waste disposal for generations because they have little emotional attachment to what’s under the water.
“We need to get political will and resources going to clean it up.”
Professor Johnston’s research focus is the effects of pollutants on estuarine life, taking both an ecological and ecotoxicological perspective and “using field experimentation wherever possible”, her web page says.
Her research has taken her from the tropical waters of the Great Barrier Reef to Antarctica, where she has studied the impact of climate change on ecosystems on the polar seabed.
UNSW deputy vice-chancellor (research) Les Field, who is also the academy’s secretary for science policy, said Professor Johnston was a deserving recipient.
“Emma is a research powerhouse in marine science and an academic leader at UNSW as well as being an excellent role model to younger scientists, both here and across Australia.”
Small satellite-tracking devices attached to sea turtles swimming off Florida’s coast have delivered first-of-its-kind data that could help unlock they mystery of what endangered turtles do during the “lost years.”
The “lost years” refers to the time after turtles hatch and head to sea where they remain for many years before returning to near-shore waters as large juveniles. The time period is often referred to as the “lost years” because not much has been known about where the young turtles go and how they interact with their oceanic environment — until now.
“What is exciting is that we provide the first look at the early behavior and movements of young sea turtles in the wild,” said UCF biologist Kate Mansfield, who led the team. “Before this study, most of the scientific information about the early life history of sea turtles was inferred through genetics studies, opportunistic sightings offshore, or laboratory-based studies. With real observations of turtles in their natural environment, we are able to examine and reevaluate existing hypotheses about the turtles’ early life history. This knowledge may help managers provide better protection for these threatened and endangered species.”
A team of scientists from the UCF, Florida Atlantic University, University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, and University of Wisconsin, tracked 17 loggerhead turtles for 27 to 220 days in the open ocean using small, solar-powered satellite tags. The goal was to better understand the turtles’ movements, habitat preferences, and what role temperature may play in early sea turtle life history.
Some of the findings challenge previously held beliefs.
While the turtles remain in oceanic waters (traveling between 124 miles to 2,672 miles) off the continental shelf and the loggerhead turtles sought the surface of the water as predicted, the study found that the turtles do not necessarily remain within the currents associated with the North Atlantic subtropical gyre. It was historically thought that loggerhead turtles hatching from Florida’s east coast complete a long, developmental migration in a large circle around the Atlantic entrained in these currents. But the team’s data suggest that turtles may drop out of these currents into the middle of the Atlantic or the Sargasso Sea.
The team also found that while the turtles mostly stayed at the sea surface, where they were exposed to the sun’s energy, the turtles’ shells registered more heat than anticipated (as recorded by sensors in the satellite tags), leading the team to consider a new hypothesis about why the turtles seek refuge in Sargassum. It is a type of seaweed found on the surface of the water in the deep ocean long associated with young sea turtles.
“We propose that young turtles remain at the sea surface to gain a thermal benefit,” Mansfield said. “This makes sense because the turtles are cold blooded animals. By remaining at the sea surface, and by associating with Sargassum habitat, turtles gain a thermal refuge of sorts that may help enhance growth and feeding rates, among other physiological benefits.”
More research will be needed, but it’s a start at cracking the “lost years” mystery.
The findings are important because the loggerhead turtles along with other sea turtles are threatened or endangered species. Florida beaches are important to their survival because they provide important nesting grounds in North America. More than 80% of Atlantic loggerheads nest along Florida’s coast. There are other important nesting grounds and nursing areas for sea turtles in the western hemisphere found from as far north as Virginia to South America and the Caribbean.
“From the time they leave our shores, we don’t hear anything about them until they surface near the Canary Islands, which is like their primary school years,” said Florida Atlantic University professor Jeannette Wyneken, the study’s co- PI and author. “There’s a whole lot that happens during the Atlantic crossing that we knew nothing about. Our work helps to redefine Atlantic loggerhead nursery grounds and early loggerhead habitat use.”
Mansfield joined UCF in 2013. She has a Ph.D. from the Virginia Institute of Marine Science and a master’s degree from the Rosenstiel School of Marine and Atmospheric Science at the University of Miami. She previously worked at Florida International University, through the Cooperative Institute for Marine and Atmospheric Studies (CIMAS) in association with the National Oceanographic and Atmospheric Administration and the National Marine Fisheries Services. She was a National Academies NRC postdoctoral associate based at NOAA’s Southeast Fisheries Science Center, and remains an affiliate faculty in Florida Atlantic University’s biology department where Wyneken is based.
With colleagues at each institution Mansfield conducted research that has helped further the understanding of the sea turtle “lost years” and sea turtle life history as a whole. For example she and Wyneken developed a satellite tagging method using a non-toxic manicure acrylic, old wetsuits, and hair-extension glue to attach satellite tags to small turtles. Tagging small turtles is very difficult by traditional means because of their small size and how fast they grow.
Mansfield is currently working under grants from NOAA and the Florida Sea Turtle License Plate fund to conduct work on the sea turtle “lost years.”
Other members on the team are: Wyneken, Warren P. Porter from the University of Wisconsin and Jiangang Luo from the University of Miami.
Though present in more than 6,000 living species of fish, the adipose fin, a small appendage that lies between the dorsal fin and tail, has no clear function and is thought to be vestigial. However, a new study analyzing their origins finds that these fins arose repeatedly and independently in multiple species. In addition, adipose fins appear to have repeatedly and independently evolved a skeleton, offering a glimpse into how new tissue types and structural complexity evolve in vertebrate appendages.
Adipose fins therefore represent a prime example of convergent evolution and new model for exploring the evolution of vertebrate limbs and appendages, report scientists from the University of Chicago in theProceedings of the Royal Society B on March 5.
"Vertebrates in general have conserved body plans, and new appendages, whether fins or limbs, evolve rarely," said senior author Michael Coates, PhD, chair of the Committee on Evolutionary Biology at the University of Chicago. "Here, we have a natural experiment re-run repeatedly, providing a superb new system in which to explore novelty and change."
Usually small and structurally simple, adipose fins tend to get attention only when they are clipped from farm-raised trout and salmon as a tag. Despite their presence in thousands of fish species, they have been dismissed as a remnant of a once-functional fin. This assumption puzzled Coates and his co-authors, as they saw no evidence of deterioration in adipose fin structure or function in the fossil record.
To study the evolutionary origins of this fin, Coates and lead author Thomas Stewart, graduate student in organismal biology and anatomy at the University of Chicago, turned to a technique known as ancestral-state reconstruction. With co-author W. Leo Smith, PhD, from the Biodiversity Institute at the University of Kansas, they created an evolutionary tree describing the relationships between fish with and without adipose fins, using genetic information from more than 200 ray-finned fish and fossil data from known time points. They then used statistical models to predict when and in what species the adipose fin might have first evolved.
They found that adipose fins originated multiple times, independently, in catfish and other groups of ray-finned fishes -- a striking example of convergent evolution over a vast range of species.
"It's pretty incredible that a structure which is incredibly common could be so misunderstood," Stewart said. "Our finding, that adipose fins have evolved repeatedly, shows that this structure, long assumed to be more-or-less useless, might be very important to some fishes. It's exciting because it opens up new questions."
More than 600 species of fish were studied in the course of this research, including many from the collections of the Field Museum in Chicago. This analysis revealed that a number of complex skeletal structures, including spines, plates, fin rays and cartilage discs, evolved independently in the adipose fins of different species. And while studies of the fossil record have suggested that new fins originate in a predictable and repeated manner, adipose fins demonstrate multiple routes to building new appendages.
"These results challenge what was generally thought for how new fins and limbs evolve, and shed new light on ways to explore the full range of vertebrate limb and fin diversity," Stewart notes.
The study, "The origins of adipose fins: an analysis of homoplasy and the serial homology of vertebrate appendages," was supported by the National Science Foundation and the University of Chicago Division of Biological Sciences.
Have you ever been snorkelling or scuba diving on a windy day when there are lots of waves? Did you notice how much that flow of water against your body affected your ability to swim and control your movements underwater? Well, fish feel the same way!
Changing waves and currents can keep fish on the move. Photo: Jordan Casey
Water flow, in waves and currents, plays a huge role in determining whether fish can survive in freshwater or marine habitats. Some species, such as tuna or salmon, are designed for high speed swimming, and thrive in fast flowing water.
Others, such as pufferfish, are not so well equipped to handle the challenges of living in high flow environments, and prefer the peace and calm of sheltered lagoons.
Stay calm. Photo: Flickr/ Motelface, CC BY-NC-ND
But even good swimmers have their limits. For example, high rates of water discharge from hydroelectric dams can hinder the upstream movements of fish – think of North American salmon or Macquarie perch in Australia.
Not all individual fish are affected the same, of course. Bigger, stronger adults are generally more capable of fighting against strong currents, but smaller, younger fish will be less likely to make it. This has obvious consequences for the age structure and survival of fish populations in the long run.
Waves, coastlines and coral reefs
On the Australian coastline, waves created by winds are a major physical force that fish have to contend with.
Some fish species are “rovers” without a fixed home range, and constantly swim over large areas in search of food or mates. Examples include species of surgeonfish and parrotfish. Since they do not need to defend a territory, these fish can take advantage of waves to help them move around, much like surfers do.
In contrast, many other species, such as damselfish, have small territories that they defend vigorously against unwelcome intruders to protect their food and other resources. To do this, they constantly have to swim against the water flow to avoid being swept away.
Colleagues and I have found that fish spend a lot more energy when they have to swim against big waves compared to a regular, steady current at the same average speed. This makes sense: humans also burn a lot more energy during interval training (when constantly changing between a sprint and a jog) compared to running at a constant speed.
Shiner surfperch in swim tunnel.
Many fish species regularly face these challenges, especially on Australia’s Great Barrier Reef.
Coral reefs are shallow habitats because corals need light to photosynthesise and produce their food. Because of their proximity to the surface, coral reefs are often very wavy habitats. This poses a real challenge for the estimated 25% of marine species found on coral reefs, 4,000 of which are fish.
Climate change
Researchers are increasingly concerned that accelerating changes in weather patterns are affecting fish and other aquatic organisms. Rivers, lakes and coastal habitats are ecologically, socially and economically important places, so it’s worth investing the time to research the impacts of climate change on these areas.
How disturbances from waves affect the movements of predators and prey likely depends on their relative size. Photo: Jordan Casey
In addition to warming temperatures and acidified oceans, sea surface levels, and thus tidal amplitudes, are also predicted to rise as a consequence of climate change.
Already, these trends in weather are being documented. Storms are also increasing in frequency and intensity in ocean basins around the globe, according to the chapter on Ocean Change in the International Panel on Climate Change’s report last year. With higher winds and larger tides come bigger waves.
Waves, tides and currents are an everyday part of life for fish living in fast-flowing waters, but new extremes in wind speed and wave height may push some species over the edge.
What can fish do?
If waves are costly for some fish, then why don’t they move to calmer locations? Fish can swim, after all. And some won’t even have to swim very far to reach calmer waters. Water velocity can vary across very small scales on coral reefs.
A new underwater instrument was developed at James Cook University to measure wave forces on the sea floor.
The instrument on a sheltered reef location with the guide rod construction and drag-sphere placement. Photo: Jacob L. Johansen, CC BY
A study from January this year using this device showed that water speeds decrease dramatically the deeper you go on coral reefs at Lizard Island. On a windy day, the water flow speed at 9m below the surface is about one quarter of the flow speed at 3m depth.
But there are many reasons why fish might not move to calmer reefs or go deeper to avoid waves:
sunlight is reduced with increasing water depth, so the shallowest, and waviest, part of the reef, where corals receive the most sunlight, is also the most productive and best habitat for fish
waves near the surface mix the water and carry the nutrients and plankton that feed fish
good places to live are at premium on coral reefs and species are all vying for space. This means that fish wanting to move will have to compete with already established residents and dislodge them if they want to take over their homes.
What can we do?
Our understanding of how fish deal with waves, let alone adapt to changes in their flow environment, is very limited.
Answers to many important questions remain elusive – what aspects of their shape, physiology and behaviour allow certain species to thrive in their current habitats?
How do waves affect important phenomena like the outcome of predator-prey encounters, competition between individuals, or the survival of small, larval fish on the reef?
How does water flow interact with other stressors like temperature changes, ocean acidification and fishing pressure in shaping our changing marine communities?
Ultimately, more research into these questions will help us understand how fish might respond to expected changes in their flow environment. These answers will be critical to inform marine resource managers and help them identify and target species that are especially sensitive to increases in wave intensity.
Dominique Roche receives funding from the Australian Research Council Centre of Excellence for Coral Reef Studies.
Australians love seafood. We each consumed an average of 25 kilograms of seafood in 2010 – an amount that has increased significantly over the last 30 years. Worldwide, fish consumption now exceeds beef. Despite our love of fish, more than two-thirds of Australians think that our fisheries are unsustainable, a view that is strongly at odds with the scientific evidence.
We love our fish ‘n’ chips, but most Australians don’t think our fisheries are sustainable. Photo: Simon Collison/Flickr, CC BY-NC-ND
Two current reports on Australia’s wild catch fisheries reveal stark differences in the way scientists and Australians view the sustainability of fish stocks. While scientists assess most stocks as sustainable, the community sees it differently. Less than one in three Australians perceive the wild catch commercial fishing industry as sustainable.
What we know
Last year, the Fisheries Research and Development Corporation published an extensive assessment of the status of Australia’s commercial fish stocks. The report assessed 150 stocks of 49 species, which make up the bulk of the commercially significant fisheries (approximately 70% of the commercial wild catch by volume and 80% by value).
The report tells a positive picture: 98 stocks were classified as “sustainable”, 11 as “transitional”, 39 were “undefined” due to insufficient data, and just two – Southern Bluefin Tuna and School Shark – were assessed as overfished.
This isn’t a comprehensive survey. Some stocks could not be assessed because information was not adequate. The report doesn’t assess all commercial species, or consider sustainability of the broader marine environment. But it shows clearly that more than more than 90% of the total catch of the species considered is being fished sustainably. This is good news for consumers of wild caught Australian seafood.
What we think we know
But last week, the Fisheries Research and Development Corporation (FRDC) released the results of a recent survey of community perceptions of the Australian fishing industry. The online survey of 1021 respondents shows that only 30% believe that the commercial wild catch fishing sector is sustainable.
Because of this gap between science and community perceptions, there is a real risk of limited community approval or acceptance of fisheries management.
In other words, Australia’s commercial fisheries lack a “social licence” to operate. This means that when controversy arises — as it did in conflict over the “super trawler” Margiris — Australians are unlikely to support these fisheries.
The 142-metre 10,000-tonne MV Margiris, the world’s second largest super trawler, arriving at Port Lincoln, South Australia, in August 2012. Photo: AAP/Nat Kilpatrick
Licensed to fish?
Why the gap? Other natural resource industries provide some valuable lessons.
First, the Australian fishing industry may be being defined by its past. Despite improvements in management and practises, poor past performance can contribute to today’s perceptions of an industry.
The survey released last week shows that 80% of the Australian public are unaware or unsure of changes put in place to improve fishing industry sustainability in recent decades.
Second, the community might be generalising perceptions about international fisheries to Australian fisheries. Imported seafood, mainly from Thailand, China, Vietnam and New Zealand, made up 72% of the seafood consumed in Australia in 2008/09.
Third, the public judge wild catch fisheries based on their knowledge of it. This knowledge rarely comes from people directly involved in the industry, and much more commonly comes from newspapers, radio and television. Media headlines grab public attention, yet the depth of information portrayed is often shallow and the opportunity to meaningfully learn from scientific reports is limited.
But it’s a two-way street. We need more accessible information on fisheries management, and science needs to address the issues that concern the community, if Australians are to make informed judgements.
What we think of bigger businesses
Compounding those problems is the lack of visibility of commercial fishers in many communities. Social licence is often built through personal interaction and trust, and an industry that lacks visibility has few opportunities to build this trust.
Thanks to efforts to improve economic efficiency and sustainability, Australia’s commercial wild catch fisheries now employ fewer people, and have shifted to larger, more corporate fishing businesses. Commercial fishing activity has also been reduced in near-shore areas used by recreational fishers. This has the unintended side effect of reducing the visibility of commercial fishing and the sense of familiarity for the general public. With less connection and less visibility, commercial wild catch fishers operate almost out of sight.
The shift to larger businesses and in some cases larger boats may itself reduce trust in wild catch fisheries. Multiple studies (based on energy, forestry and farming) have found that the public perceive activities more negatively if they are conducted by large businesses or on a large scale.
Fisheries policies —intended to improve productivity and encouraging economies of scale — may have the unintended consequence of reducing the acceptability of the industry.
The lack of a social licence to operate for Australia’s commercial fishing sector means fisheries can struggle to find community support when controversy arises.
But the latest FRDC survey suggests there is room for change. While only 30% of Australians believe our fisheries are sustainable, a further 37% sat on the fence. Better access to trusted information and increased familiarity with the fishing industry can help address this gap.
Peter O'Brien is a Director of the Fisheries Research and Development Corporation.
Jacki Schirmer and Lain Dare do not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article. They also have no relevant affiliations.
The hairy legs of water striders are artfully designed to strike a balance between the water capillary action and gravity, Chinese researchers have discovered.
Spacing of the water striders' leg hairs are optimised so they are close enough not to penetrate the water's surface during impact Photo: Tim Vickers/Wikimedia Commons
They found the spacing of the insect's leg hairs fits a formula that takes into account the contact angle of the hairs and fluid mechanics to ensure maximum load-carrying capacity and floating stability.
The results, reported today in Proceedings of the Royal Society A not only provide an insight into the remarkable ability of these insects, but has implications for the design of miniature rafts and water strider-inspired robots that can float stably and move easily across water.
Nature abounds with examples of water-repelling surfaces such as the lotus leaf and insects' wings that have already inspired a number of technological advances.
"Many researchers have tried to understand how the hairy structures render legs or wings of some insects water repellent from the point of view of surface physics and chemistry," says Associate Professor Huiling Duan, from the Department of Mechanics and Aerospace Engineering at Peking University.
Previous research had suggested these hairy surfaces were superhydrophobic, hence their ability to repel water.
"In fact, water repellency of hairy surfaces depends on the size, spacing and orientation of the hairs in micro-scale," says Duan.
To investigate how hairs interact to repel water, Duan and colleagues examined the layout of the tiny hairs, or setae, on water striders' legs and fly wings.
They found the spacing of the water striders' leg hairs, and the hairs on a fly's wing, is optimised so that the hairs are close enough so as to not penetrate the water's surface during impact, but not so close together it becomes inefficient.
"More densely packed setae will definitely cost more biological energy, and increase the adhesion and energy dissipation during the movement of water striders on water," Duan says.
The spacing is designed to maximise the supporting force provided by the water surface tension which creates a meniscus — a curved surface of water — in between each individual hair. It is also designed so the water doesn't cling to the hair, enabling the water strider to move quickly and easily across the water surface.
"For insects living on water, low energy dissipation is needed for them to lift their legs from water so they can quickly move and flee away from possible threats," the researchers' write.
"During a lifting process, the convex contour enables the detaching of the contact menisci to happen gradually from both sides of a hairy surface instead of the simultaneous detachment of all the menisci, which will greatly reduce the force and energy needed to lift a hairy surface from water."
The researchers also found thicker hairs have greater load-carrying capacity as compared to thin hairs.
A JOINT study about to begin, will determine whether populations of freshwater catfish in the country’s tropical and sub-tropical regions are free of the Edwardsiella ictaluri bacterium.
Prof Lymbery says the study will give some insight into northern freshwater fish populations. Photo: David Gardiner
The bacterium can cause 'Enteric Septicemia of Catfish' and is potentially deadly to populations of freshwater fish in northern Australia.
Affected fish appear disorientated and can chase their tails.
Murdoch University’s Alan Lymbery says the study will investigate high risk localities in the Kimberley, Northern Territory and northern Queensland and was prompted by reports of the bacterium in imported fish and aquarium facilities.
“As far as we know through passive surveillance it’s not in wild populations, but there hasn’t been an active survey at all—if it’s here we think it would have come in with imported ornamental aquarium fish,” Professor Lymbery says.
“The survey is a targeted design which is looking at high risk populations or high risk localities for the bacterium.
“We’re looking at rivers which have major population centres on them and we’re targeting our particular sites around major towns or immediately downstream from major towns.”
Prof Lymbery says the survey for the study was designed in collaboration.
“We use a bacterial test first … if it looks like we’ve got the bacterium then we’ll go back and we’ll do some DNA testing of that fish,” he says.
“Given some assumptions, if we do not find the bacteria in around 20 fish from a number of high risk sites across northern Australia then we can be confident that native fishes are disease free.”
Prof Lymbery says the study will give some insight into northern freshwater fish populations.
“The disease caused by the bacterium can be quite severe in fish populations and can be devastating to aquaculture,” he says.
“The bacterium can have a quite high mortality and it can kill the fish rapidly.
“There is a big ornamental fish trade over the world … so it has some economic importance for Australia to be disease free.
“Australia has also got a very unique freshwater fish fauna, if there is anything we can do to keep exotic diseases out of our natural water ways it’s going to help with the conservation of our freshwater fish fauna.”
Prof Lymbery says he hopes the study will also raise awareness of the disease so fishers or fish owners can report it if they see it.
The surveys are expected to be completed by the end of the year.
Notes:
The study, funded by the federal Department of Agriculture, is being conducted by Murdoch University’s Freshwater Fish Group and Fish Health Unit with help from the WA Department of Agriculture and Food, Northern Territory Department of Resources, CSIRO and James Cook University.
Australia is almost a degree warmer, on average, than it was a century ago, according to the State of the Climate 2014 report compiled by the CSIRO and Bureau of Meteorology.
Summary of findings from the State of the Climate 2014 report. State of the Climate 2014.
Australia has warmed by 0.9C since 1910 – roughly in line with global rates of atmospheric warming – and is set to continue warming at a rate that depends on how fast greenhouse emissions can be reduced.
The finding reiterates the previous State of the Climate report, released in 2012.
According to the 2014 report:
Seven of Australia’s 10 warmest years have happened since 1998;
Over the past 15 years, very warm months have occurred at five times the long-term average, while very cool months have declined by a third;
By 2070, temperatures will be anywhere between 1C and 5C warmer than the 1980-1999 average, depending on future emissions cuts
Winter rainfall has declined by 17% since 1970 in Australia’s southwest, and by 15% since the mid-1990s in the southeast;
Tropical cyclones are forecast to decrease in frequency but increase in severity;
Sea-level rises will increase the frequency of extreme sea-level events.
More heatwaves
Bureau of Meteorology assistant director Peter May said the report shows that Australia is “loading the dice” for more future heatwaves.
“The warming both in Australia and globally is certain, and is human-induced. The impacts of that are making themselves felt through an increased frequency of heatwaves, and fewer periods of extreme cold temperatures,” he said.
“We are locked into a certain degree of future changes even if we stopped carbon emissions tomorrow.”
He said it was beyond the report’s scope to advocate for political action, or to advise on whether the government’s commitment to cut emissions by 5% by 2020 goes far enough.
“(The report is) really about providing information for policymakers - it’s neither the Bureau nor CSIRO’s role to dictate what those responses should be. We’re providing the scientific advice on the way things are,” May said.
Sarah Perkins, a climate research fellow at the University of New South Wales, said: “No matter how you slice and dice it, the evidence is clear that human-induced climate change is continuing to increase the risk of extreme weather and temperatures.”
“This is coming from Australia’s national research institutions. We’re all saying it, because the science is clear and the evidence is there for us all to see,” she said.
Heatwaves are a pressing issue for Australia, both because of their direct link to warming temperatures, and because of their rapid impacts on health, Perkins said.
“When you have a heatwave it kills people and damages infrastructure within a matter of days - when you have a drought the crops die slowly, the economic impacts are much slower. Impacts via short, intense extreme temperatures are generally more measurable.”
“Even if we did completely switch to green technology tomorrow, the next 50 years we would see this projected change. However in the next 100 years we could start to see a reduction in extreme events and changes to rainfall because we’ve started to make those changes.”
“More and more reports are coming out globally. Despite the polar vortex bringing some very cold conditions to parts of America, they were not on the same scale as the record-breaking hot temperatures that are consistently occurring across the globe. No state in America had its coldest winter on record, and many other parts of the Northern Hemisphere had very mild winters, including Alaska.”
Consistent findings
Roger Jones, a professorial research fellow at Victoria University, said the findings were consistent with a recent report from the Climate Council that dangerous fire weather is already on the rise.
“Fire weather is currently around the worst case predicted for 2030-2050,” he said.
The picture in terms of rainfall is less clear-cut. Australia had very wet years in 2010 and 2011, and overall rainfall has increased. But many heavily populated areas are enduring declining rainfall, Jones said.
“If you do a spatial average over Australia you find, as the report says, that rainfall has increased slightly. But if you do a population-weighted average it has decreased. The increase in rainfall in northern Australia coincides with warming in the region,” he said.
Sophie Lewis, a postdoctoral research fellow at the University of Melbourne, said the report reflects an increase in scientific knowledge since the 2012 report.
“We now have studies for extreme events in Australia that provide scientifically robust attribution that can be used to understand observed events. We knew that by increasing average temperatures we would see an increase in the frequency and severity of extremes, but we hadn’t analysed specific events. That’s why we’re seeing these official reports issue quite definitive statements about the causes of extremes,” she said.
The ability of deep sea fish to plumb new depths may be constrained by biochemistry, new research by an international team has found.
This photo of hadal snailfish (Pseudoliparis amblystomopsis), snapped at 7500 metres down, is the second deepest observation of a live fish.
The research, published today in the Proceedings of the National Academy of Sciences, explains why there are no known fish species below 8400 metres, despite the presence of other marine animals such as anemones, crustaceans and sea cucumbers.
Based on previous work, the researchers, led by biologist Professor Paul Yancey from Whitman College, Washington believed that the depth limits of fish were related to levels of osmolytes present in their bodies.
Osmolytes are soluble organic compounds that counteract the effects of pressure on proteins by altering water structure so that the tendency for pressure to force water molecules into the interior of cells is reduced and the cells can keep functioning.
Gelatinous texture
To test their theory, the researchers captured five specimens of the second deepest known fish, the hadal snailfish (Notoliparis kermadecensis), from a depth of 7000 metres in the Kermadec Trench to the north east of New Zealand.
"The Kermadec Trench is one of the deepest in the world, and no hadal snailfish had been caught there since the 1950s," says Dr Ashley Rowden from the National Institute of Water and Atmospheric Research in Wellington, New Zealand, who was part the study team.
The fish were captured from a 28-metre boat and bringing them to the surface took more than three hours in rough seas, requiring determination and strong stomachs from those on board.
"Out of their natural environment, snail fish feel like water-filled condoms," says Rowden. "Like other fish from the deepest hadal zone [region below 6000 metres] their gelatinous texture is an adaptation to extreme pressure (around 10Mpa or 1000 times the surface atmospheric pressure)."
"They are relatively delicate organisms and don't survive the journey to the surface, possibly due to the pressure changes they experience as they journey up from 7000 metres below," Rowden says.
Osmolyte levels
Once back on dry land, the researchers compared the levels of the osmolyte trimethylamine N-oxide (TMAO) in the hadal snailfish with that in other bony fishes from a range of bathymetric zones in the ocean.
The concentration of TMAO present in the muscle tissue of the snailfish was significantly higher than for fish living at shallower depths.
When they extrapolated their findings, the researchers found that it is unlikely that bony fish could survive below 8,200 metres, because the high concentrations of TMAO that would be required to combat the effects of pressure can also reverse cellular osmosis gradients — the difference between the salinity levels inside and outside the cells.
"Other research has shown a general increase in TMAO levels from shallow water dwellers to fish living at 5000 metres," Rowden adds.
"The snailfish came from 2000 metres below where previous samples had been taken, and represented a big jump in TMAO levels."
Early days
Bony fish are one of the largest animal groups on Earth and have exploited most available habitats, Rowden explains.
"There is the potential for organisms to get to every corner of the world's environment, but the deepest oceans are yet to be colonised by bony fish.
"This research indicates that they are biochemically constrained from inhabiting the deepest parts of the ocean, but as deep-sea fish evolved only relatively recently, geologically speaking, over time they may evolve further adaptations to cope with the unique demands of the hadal environment."
A study is trying to identify the best cane toad call to attract the pests into traps.
Researchers are touring northern Australia, recording and identifying the most seductive calls which cane toads use.
Research assistant Richard Duffy says the mating call from male toads attracts both sexes.
Research Assistant Richard Duffy hunting for cane toad calls in northern Australia. Photo: Tyne McConnon
"Males will assemble themselves around a body of water and they will call and do their best to sound their greatest.
"But also sometimes you attract males as well because males may have a better chance of finding a female if they go and sit next to Barry White on the edge of the water."
The four year study is trying to make cane toad traps, more efficient and attractive to toads.
PhD student and researcher Kiyomi Yasumiba says she believes the deeper calls are the most popular.
"In general it's the males with low frequency calls and who have a large body size."
Mr Duffy and Ms Yasumiba have collected sounds from Queensland and Western Australia.
Mr Duffy says they are collecting calls from various states as they believe there are different calls for different groups of toads.
"We are going to compare different sites to see whether there are regional dialects, different accents from Queensland and Western Australia."
The study will record 30 individual toad calls from each location which will then be tested.
Ms Yasumiba says the calls are tested by placing a toad in an area with different calls playing, then documenting which way the toad heads.
