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Why Australia’s northern rivers are so full of fish

Australian native freshwater species, fisheries, research, waterways/wetlands

Mar 182014

Original story at ABC Darwin

New research is revealing how North Australian rivers support more fish than would seem possible. Surgically implanted tracking devices are showing how barramundi make ends meet.

Northern Australia has big fish and lots of them...

Charles Darwin University's Associate Professor David Crook, has perfected the art of surgically implanting fish with small radio tracking devices.

"You just make a little incision with a scalpel and pop the tag in and stitch it up, and the fish is back in the water in a minute or two," he says.

In this way, 40 barramundi and 30 fork-tail catfish were equipped with radio transmitters. The electronic addition to the fish allowed scientists to keep track of their movements.

But it's not about helping the fishing obsessed find their next catch; the researchers are trying to solve a much bigger riddle.

Associate Professor David Crook surgically implants a radio tracking device into a barramundi while research assistant Duncan Buckle records data.

Fish mystery

Australia's tropical waterways are famous for being some of the best places in the world to go fishing. What looks like a small, muddy creek, can be teeming with fish. And up North, it's not just tiddlers; barramundi and threadfin salmon regularly grow over a metre long, while river sharks and sawfish are even bigger.

When scientists took a look at our tropical rivers, the huge numbers of big fish just didn't quite add up.

"It seems like there's not enough energy just in the main channel to support the productivity of the fisheries that we have," says Professor Crook.

Lurking somewhere in the South Alligator river is this magnificent 137cm Barramundi!

But as any fisherman will confirm, knowing what the fish get up to below the surface can be very hard to figure out. So Professor Crook turned to surgically implanted radio trackers to try and understand how rivers in the north can be home to such a wealth of fish.

Secret revealed

At first the trackers showed the barramundi weren't doing very much at all; they didn't move very far from where they were released. But with the first rains of the wet season, the barramundi were transformed.

"Pretty much immediately the fish moved straight out onto the floodplains within a day or two of the water coming up on the floodplain," says Professor Crook.

The barramundi became highly active and researchers had to adjust their equipment to keep up.

"We have to use a helicopter to find the fish because they are moving around so much," Professor Crook says.

The tracking devices showed that the wet season allowed barramundi and fork-tailed catfish to take advantage of a large part of the northern landscape. Professor Crook's stand-out performer regularly led him between the river and the floodplain over the wet season.

"That fish has probably been making movements in the order of hundreds of kilometres over that period," he says.

Feeding far and wide

What appears to be a small river or creek loaded with fish in the dry season, is really more of a holding pond for fish who make their best living far and wide in wet season flood waters.

"Without the connectivity between the estuary and the floodplain there's no way our rivers could support as many barramundi and other fish as they do," says Professor Crook.

The research has shown scientists that a barramundi is not just a product of the billabong or river where it may end up on the end of a fisherman's line.

"At least 35 per cent of the energy in the flesh of a barramundi actually comes from the floodplains," Professor Crook says.

The work proves what many have suspected; that wet season flooding drives the health and productivity of tropical rivers and estuaries. Professor Crook says the knowledge will help inform the future management of water in Northern Australia.

"That's what we're really trying to understand; what sort of processes do we need to keep in place to make sure we continue to have productive fisheries in the future?"

Robot Fish From MIT Swims Like The Real Thing

Interest, research

Mar 162014

Original story from International Science Times

MIT unveiled a robotic fish this week, a soft, silicone machine that can move autonomously through water. In the new journal Soft Robotics, MIT researchers describe the robot's ability to execute escape manoeuvres like a real fish, turning 100 degrees in as many milliseconds, with the help of a carbon dioxide canister and a heap of machinery in the "brains" of the fish. The robot may eventually be used to swim in real fish colonies in order to gather data on their behaviour.

"Because of their body's capability to bend and twist, these robots are capable of very compliant motion, and they are also capable of very rapid, agile maneuvers, which pushes the envelope on what machines can do today," says MIT researcher Daniela Rus in the video below.

The inside of the fish is made up of control units in the head, a carbon dioxide canister in the head and abdomen and tubes which go from the CO2 canister to the tail. Changes in the level of CO2 determine how fast the fish moves, and the amount the tubes inflate changes the fish's angle. The soft robot can be directed by an operator via a wireless receiver in the fish's head. Silicone rubber (waterproof, of course) covers the outside of the fish.

Soft robots can offer several advantages over so-called hard robots (think of pretty much every other robot you've ever seen). Most robotsprioritize avoiding collisions--they don't want to be damaged or fall over--which means that they may take an inefficient path to get where they're going. But soft robots can withstand collision, and may even benefit from knocking into something.

"In some cases, it is actually advantageous for these robots to bump into the environment, because they can use these points of contact as means of getting to the destination faster," says Rus. "The fact that the body deforms continuously gives these machines an infinite range of configurations, and this is not achievable with machines that are hinged."

Last year, Rus and her colleagues showed off another incredible robotics project made up of colored blocks that spin and build themselves into modular machines. These building-block robots have to be seen to truly understood, so check them out.

Push to move threatened outback fish into captivity

Australian native freshwater species, pest species, research, threatened species, waterways/wetlands, wildlife

Mar 132014

Original story by Chrissy Arthur and Ash Moore, ABC News

Bush Heritage Australia says it is hoping recent flooding in an inland river system will help an endangered fish species.

Scaturiginichthys vermeilipinnis. Photo: © Gunther Schmida

Aquatic ecologist Adam Kerezy has been working for years to save the tiny red-finned blue-eye fish [Scaturiginichthys vermeilipinnis] from extinction.

It is only found in natural springs in central western Queensland.

Adam Kereszy at Edgbaston. Photo: Tim Bauer

Dr Kerezy says it is also seeking permission to move some of the remaining fish into captivity.

"So they only get to about three centimetres long, they only live in that particular group of springs north-east of Aramac," he said.

"The crucial thing is we have got an invasive species called gambusia, or mosquito fish or bore drain fish, and they are out there too and so my job over the last six years has been basically to try and stop them [red-finned blue-eye fish] from going extinct.

"Hopefully they will be breeding up a bit, some of them will be trying to move to new springs.

"Hopefully this year we will move some into captivity and then cross fingers and toes and everything we have got and hope that they survive but for a fish that has adapted to living in these tiny shallow springs in the middle of nowhere, it might take a little bit of work to get them to adapt to captive conditions."

Australia hatches first IVF shark

aquarium, research, threatened species

Mar 122014

Original story at Phys.org

Australia has successfully hatched its first shark born via artificial insemination with hopes that the development can ultimately be used to help breed threatened species, an aquarium said Wednesday.

The first brown banded bamboo shark pup born in Australia via Artificial Insemination is shown a at the SEA LIFE Melbourne Aquarium on March 2, 2014

The first brown banded bamboo shark (Chiloscyllium punctatum) pup born in Australia via Artificial Insemination is shown a at the SEA LIFE Melbourne Aquarium on March 2, 2014

Sea Life Melbourne Aquarium said the brown banded bamboo shark pup was born on March 3, ending a process which began in September when aquarists collected a semen sample from a shark in Mooloolaba in northeastern Australia.

This was flown to the southern city of Melbourne and inseminated into the mother the same day—making the pup the first shark to be born globally via a live semen sample transported from one facility to another, Sea Life said.

Melbourne Aquarium vet Rob Jones said the birth of the shark—which is expected to grow from its initial length of 16 centimetres (6.3 inches) to an adult size of 1.2 to 1.5 metres—was a milestone in using assisted reproductive technologies.

"This is a big leap," he told AFP.

The hatching is part of a nine-year project into understanding the reproductive behaviours of sharks, animals which are common in Australia but are little understood.

The team hope their research will help with plans to manage threatened species in the wild, in particular the critically endangered grey nurse shark.

The egg, one of several laid by the shark in November but the only viable one, was monitored weekly during its incubation period of 112 days.

"With each insemination attempt, we continue to learn about the reproductive behaviours of Australian shark species," said Melbourne Aquarium research consultant Jon Daly.

"Hopefully we can use this technology as a basis for breeding grey nurse sharks in captivity and, in years to come, boost the species' dwindling numbers in the wild."

Grey nurse sharks are considered critically endangered, with estimates that there could be as few as 1,500 left on Australia's east coast.

Sharks are a known danger for those swimming, diving and surfing around the country and are currently subject to a controversial cull in Western Australia state after a series of fatal attacks in recent years.

The policy to catch and kill any protected great white, tiger or bull shark bigger than three metres off popular west coast beaches has been condemned by conservationists.

Endangered tinker frog: breeding program may help fight deadly fungus

research, threatened species

Mar 112014

Tinker frog, Taudactylus liemi. The genus Taudactylus has unusual breeding behaviours that have made life difficult for researchers. Photo: Conrad Hoskin

Original story by Elise Worthington, ABC News

Queensland researchers are working on a world-first frog breeding program to stop the tiny, endangered tinker frog from becoming extinct.

Two of the six species of tinker frog have already been wiped out, and researchers believe the lethal amphibian Chytrid fungus is to blame.

The one- to two-centimetre-long frog, which is native only to Queensland rainforests, gets its name from its unique call, according to Professor Jean-Marc Hero from Griffith University.

"The thing that really makes them stand out is their tinker, the sound they make is like the tinker of a glass jar with a metal pen or something," he said.

Professor Hero says a new program on the Gold Coast has managed to breed the tinker frog for the first time.

"There are only six species - they are an ancient Gondwana group - and at least three of those are already gone," he said.

"We are looking to recover and support the species that are remaining."

There are only six species - they are an ancient Gondwana group - and at least three of those are already gone.

Professor Jean-Marc Hero

Saskia Lafebre from Currumbin Wildlife Sanctuary on the Gold Coast says it is an exciting development.

"The species that we are working with are almost endangered in their own right, but we are actually trying to work with these species so we can one day work with the more endangered species of tinker frogs," she said.

Ms Lafebre says it will be around two years before the new tadpoles can breed, but if all goes well there could be up to 400 tinker frogs hopping around.

"We've got large numbers of eggs, large numbers of tadpoles and hopefully we can turn that in to large numbers of metamorphs," she said.

Tinker frog's breeding behaviour unusual

The tinker frog is part of the genus Taudactylus, which has unusual breeding behaviours that have made life difficult for researchers.

Unlike other species, the tinker frog likes to lay its white eggs underground because they have no pigmentation, which leaves them susceptible to sunburn.

"We made a little bit of a mistake, where the eggs got some sunlight and they were killed almost immediately," Professor Hero said.

He says things have improved this year with hundreds of tadpoles spawned from a number of adult frogs.

"It's quite an unusual frog it has unusual behaviour and we are very lucky to be finally very successful in breeding them," he said.

The breeders hope that those frogs will then be able to breed and create a large, captive population.

"It's very important that we learn how to breed these species in captivity so we can save them from extinction," he said.

Deadly skin fungus attacking other frogs

The tinker, like many other types of frogs across the world, has fallen prey to the deadly skin fungus Chytridiomycota, which causes the animals to die from heart failure.

Professor Hero says researchers are still trying to establish how the fungus spreads, to avoid reinfecting the new tinker frogs.

"The fate of the animals is still yet to be determined because we are still struggling with what is the cause of the decline in these animals," he said.

"It's hard to know at this stage where these frogs are first infected by the zoo spores of the lethal fungus that kills them, but it's certainly in water and probably most likely the tadpole stage.

"We have to be really careful before we re-release them into the wild that they are not infected with that disease."

Constructed wetlands and ecosystem function

environment, research, waterways/wetlands

Mar 102014

Original story compiled by Kev Warburton, Freshwater Research News

A hybrid system using Flowforms in a treatment pond, in Norway. Photo: Aalang/WikiMedia Commons

The construction of wetlands has an important role to play in strategies to offset the loss of natural wetlands and treat wastewater. Typically, the effectiveness of constructed wetlands is assessed by comparing their levels of species abundance and diversity with those in natural wetlands. However, these structural indicators aren’t necessarily good measures of ecosystem function. In a study of riparian locations on the Ebro River in Spain, net ecosystem production (NEP, the balance between primary production and community respiration) was measured in matched sets of natural and constructed wetlands. Analysis revealed that water column NEP was significantly higher in natural than constructed wetlands. In the natural wetlands, NEP was highest in unvegetated habitats,while in the constructed wetlands NEP tended to be greatest in habitats dominated by submerged plants, particularly the branching alga Chara. Because previous work showed that invertebrate communities recovered rapidly in the same constructed wetlands, the new results suggested that ecosystem function recovered more slowly than ecosystem structure. Therefore, useful insights may be gained by including ecosystem function in the design and evaluation of new wetlands.

Reference: Espanol, C. et al. 2013. Is net ecosystem production higher in natural relative to constructed wetlands? Aquatic Sciences 75, 385–397.http://link.springer.com/article/10.1007/s00027-012-0284-1#page-1

The endless summer? We have some bad news as surf fades away

community, environment, research, waterways/wetlands

Mar 102014

Original story by Damien Murphy and Amanda Hoh, The Sydney Morning Herald

Every surfer who pulled up at a beach to check the waves has known the universal disappointment that goes with being told ''you should have been here yesterday''.

The phrase became part of beach lingo in the first surf film to cross over into the mainstream, Bruce Brown's The Endless Summer.

Not what they used to be: Richie Vaculik at Maroubra. Photo: Dean Sewell

Fifty years later, ''you should have been here last century'' looks like being the new reality for surfers who chase storm surf.

Latest findings by the Bureau of Meteorology predict big surf will increasingly become a thing of the past. Andrew Dowdy, lead author of a study for the bureau's Centre for Australian Weather and Climate Research, said fewer large waves were projected for eastern Australia because storms were not going to be as hostile. But while bad news for big wave riders, there was a bright side: the wave research was carried out partly due to increased concern with coastal erosion and rising sea levels.

''Our study was focused on storm waves. We found increasing greenhouse gases will likely reduce the number of storm waves for central east coast of Australia for the end of this century,'' Dr Dowdy said.

The bureau researchers took readings from wave observation buoys located six to 12 kilometres offshore from Coffs Harbour to Eden on the south coast and collated it with data and conditions high in the atmosphere about five kilometres above sea level.

''It was a new method that provided a really good indication of the risk of large waves occurring,'' Dr Dowdy said. ''We used climate models that could represent those conditions … that [showed] us how that might change in the future. They proved more consistent than previous studies, as well as allowing the influence of greenhouse gases to be clearly shown.

''It all comes down to how much greenhouse gases are in the atmosphere. We had one scenario where greenhouse gases continue to rise towards the end of the century, and another where greenhouse gas emissions stabilised. For a higher emission scenario, we can expect a 40 per cent reduction in storm events. If emissions were stabilised, we can expect 25 per cent fewer storms in the region.''

Having endured the worst year for quality surf in 60 years, surfers living along the NSW coast, but especially around Sydney, are under little illusion that something has stopped sending surf onto their beaches, points and reefs.

Maroubra surfer Richie Vaculik said the past year had been the worst for surf in years. ''You look back [to] when you were a little kid and seem to think there was always big surf, but last winter hardly any of the big wave spots - Ours [Cape Solander], Fairy Bower [Manly], the bombies around Queenscliff and Ulladulla - fired at all,'' he said.

Identifying species at risk from climate change

Australian native freshwater species, environment, research, waterways/wetlands

Mar 102014

Original story compiled by Kev Warburton, Freshwater Research News

Which aquatic species are the most vulnerable to the impacts of climate change? In theory, traits such as physiological tolerance, life history attributes, dispersal abilities and dietary and habitat requirements could be useful indicators of the vulnerability of a species to climate warming, but this possibility needs to be tested for different types of organisms. One such analysis focussed on the freshwater fish of the Murray-Darling river system in Australia, and drew on monitoring data for 39 species, plus data on 14 biological traits for the same species compiled from the literature. Of those traits, 11 showed a significant relationship with changes in species abundance observed in 2004-2010 during a period of extended drought. Trait-based rankings of drought vulnerability also agreed well with species vulnerability assessments from previous studies. The most vulnerable fish species had relatively low heat tolerance and low minimum spawning temperatures. They tended to be small-bodied species (e.g. galaxiids, pygmy perches) that feed on invertebrates, which suggested that omnivores that consume more detritus and plant material have more success in finding food during drought. Vulnerable species also tended to mature early and have a short life-span, an extended spawning season and low fecundity. These are normally considered to be “opportunistic” features typical of species adapted to unpredictable environments, but it seems that that this type of opportunism doesn’t extend to coping with long, multi-year droughts. In prolonged droughts, larger species with delayed maturation are better equipped to survive and breed later. Vulnerability rankings based on a range of traits can help to identify species at risk and prioritise conservation actions.

Reference: Chessman, B. 2013. Identifying species at risk from climate change: traits predict the drought vulnerability of freshwater fishes. Biological Conservation 160, 40–49.

http://www.parcc-web.org/parcc-project/documents/2013/02/identifying-species-at-risk-from-climate-change-traits-predict-the-drought-vulnerability-of-freshwater-fishes.pdf

Dinosaur-killing impact acidified oceans

Interest, research, waterways/wetlands

Mar 102014

Original story by Richard Ingham/AAP at the Sydney Morning Herald

The space rock that smashed into Earth 65 million years ago, famously wiping out the dinosaurs, unleashed acid rain that turned the ocean surface into a witches' brew, researchers said on Sunday.

An artist's impression of the recently identified Torvosaurus gurneyi dinosaur. Photo: Reuters

Delving into the riddle of Earth's last mass extinction, Japanese scientists said the impact instantly vapourised sulphur-rich rock, creating a vast cloud of sulphur trioxide (SO3) gas.

This mixed with water vapour to create sulphuric acid rain, which would have fallen to the planet's surface within days, acidifying the surface levels of the ocean and killing life therein.

Those species that were able to survive beneath this lethal layer eventually inherited the seas, according to the study which did not delve into the effects on land animals.

"Concentrated sulphuric acid rains and intense ocean acidification by SO3-rich impact vapours resulted in severe damage to the global ecosystem and were probably responsible for the extinction of many species," the study said.

The great smashup is known as the Cretaceous-Tertiary extinction.

It occurred when an object, believed to be an asteroid some 10 kilometres wide, whacked into the Yucatan peninsula in modern-day Mexico.

It left a crater 180 kilometres wide, ignited a firestorm and kicked up a storm of dust that was driven around the world on high winds, according to the mainstream scenario.

Between 60 and 80 per cent of species on Earth were wiped out, according to fossil surveys.

Large species suffered especially: dinosaurs which had roamed the land for some 165 million years, were replaced as the terrestrial kings by mammals.

Extinction riddle

Much speculation has been devoted to precisely how the mass die-out happened.

A common theory is that a "nuclear winter" occurred - the dust pall prevented sunlight reaching the surface, causing vegetation to shrivel and die, and dooming the species that depended on them.

Another, fiercely debated, idea adds acid rain to the mix.

Critics say the collision was far likelier to have released sulphur dioxide (SO2) than SO3, the culprit chemical in acid rain. And, they argue, it would have lingered in the stratosphere rather than fallen back to Earth.

Seeking answers, a team led by Sohsuke Ohno of the Planetary Exploration Research Centre in Chiba set up a special lab rig to replicate — on a tiny scale —what happened that fateful day.

They used a laser beam to vapourise a strand of plastic, which released a high-speed blast of plasma and caused a tiny piece of foil, made of the heavy metal tantalum, to smash into a sample of rock.

The heavy foil fragment replicated on a miniscule scale the mass of the asteroid, while the rock was of a similar makeup as the surface where the asteroid struck.

The team caused collisions ranging from 13 to 25 km per second (47,000-90,000 km per hour), and analysed the gas that was released.

The research, reported in the journal Nature Geoscience, showed that SO3 was by far the dominant molecule, not SO2.

The team also carried out a computer simulation of larger silicate particles that would have been ejected by the impact, and found they too played a part.

The articles rapidly bound with the poisonous vapour to become sulphur acid "aerosols" that fell to the surface.

Heavily acidic waters would explain the overwhelming extinction among surface species of plankton called foraminifera.

Foraminifera are single-celled creatures protected by a calcium carbonate shell, which dissolves in acidic water.

The "acid rain" scenario also helps explain other extinction riddles, including why there was a surge in the number of ferns species after the impact. Ferns love acidic, water-logged conditions such as those described in the study.

Over demanding market affects fisheries more than climate change

environment, fisheries, research, waterways/wetlands

Mar 082014

News release from Investigación y Desarrollo

Fisheries that rely on short life species, such as shrimp or sardine, have been more affected by climate change, because this phenomenon affects chlorophyll production, which is vital for phytoplankton, the main food for both species.

Fisheries that rely on short life species, such as shrimp or sardine, have been more affected by climate change.

Disclosed by the research “Socioeconomic Impact of the global change over the fishing resources of the Mexican Pacific” headed by Ernesto A. Chávez Ortiz, from the National Polytechnic Institute (IPN).

Work performed at the Interdisciplinary Center of Marine Sciences (CICIMAR) from the IPN, indicates that in the last five years there have been no “spectacular” changes attributable to climate change, what has affected the fishing resources more is the over demanding market.

“Globally, a great part of the fishing resources is being exploited to its maximum capacity, several have overpass its regeneration capacities and are overexploited” Chávez Ortiz points out.

The specialist at CICIMAR details that the research consisted in exploratory weather and fisheries analysis, and confirmed what has been intuitively said for a while: a lot of the variability in the fishing is due to climate change, the problem is that evidence hadn’t been found to prove it.

“In the research we found a clear and objective way to show it: we took historical data from FAO regarding fisheries, available since 1950, compared it to the data of weather variability and found high correlations.

Change patterns were identified, for example, while in the 70’s the sardine production increases, in the 80’s it decreases below average levels, meanwhile shrimp fishing increased above average but decreased in the 90’s.

This way, climate changes were identified in the mid 70’s and late 80’s that affected the fishing of sardine and shrimp in the Mexican Pacific Ocean, possibly attributable to El Niño. In the particular case of the shrimp, it effects are related to an input of water from the continent; for example, when there’s a good raining season, there will be an increase in the crustacean production, which is reduced when it doesn’t rain.

The researcher at CICIMAR clarifies that the analysis of the fisheries, examined in the guidelines of this project, used of a simulation model that allows to evaluate optimal exploitation strategies, possible change in the biomass of the analyzed resources, as well as the long term effects of climate change, like cyclones, and set them apart of those caused by the intensity of the fishing. (Agencia ID)

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