Agency: Cordis | Branch: H2020 | Program: CSA | Phase: INT-01-2015 | Award Amount: 1.06M | Year: 2016
Mesopelagic Southern Ocean Prey and Predators The underlying concept of MESOPP is the creation of a collaborative network and associated e-infrastructure (marine ecosystem information system) between European and Australian research teams/institutes sharing similar interests in the Southern Ocean and Antarctica, its marine ecosystem functioning and the rapid changes occurring with the climate warming and the exploitation of marine resources. While MESOPP will focus on the enhancement of collaborations by eliminating various obstacles in establishing a common methodology and a connected network of databases of acoustic data for the estimation of micronekton biomass and validation of models, it will also contribute to a better predictive understanding of the SO based on furthering the knowledge base on key functional groups of micronekton and processes which determine ecosystem dynamics from physics to large oceanic predators. This first project and associated implementation (science network and specification of an infrastructure) should constitute the nucleus of a larger international programme of acoustic monitoring and micronekton modelling to be integrated in the general framework of ocean observation following a roadmap that will be prepared during the project.
News Article | October 26, 2015
Earlier this year, we learned some worrisome climate news. Although Antarctic scientists have been most concerned about loss of ice in the western part of Antarctica, a study in Nature Geoscience suggested a vulnerability in the much larger ice sheet of East Antarctica, as well. East Antarctica’s enormous Totten Glacier, you see, has a key similarity with the glaciers of West Antarctica — namely, it is rooted deep below sea level. This means that it is potentially exposed to warm ocean waters, and the study in March uncovered a deep and 5-kilometer wide subsea valley beneath the glacier’s oceanfront ice shelf that, the authors said, could be a route for warm offshore water to reach its base. This might explain why the glacier has been observed to be thinning and lowering, or losing elevation, over time, they noted. Located along East Antarctica’s Sabrina Coast, Totten glacier is the ice sheet’s largest. It holds back 3.9 meters of potential sea level rise, or over 12 feet, and connects with the very deep and vast Aurora Subglacial Basin, which is also rooted well below sea level. So the results were treated as being of enormous consequence. But they’re not the end of the story, as there is vastly more to learn about Totten glacier. A new study out in Geophysical Research Letters reaffirms some of these core concerns about Totten’s melt — while also appearing to partly alleviate others. Xin Li, a researcher at the University of California, Irvine, worked with a team from her institution and NASA’s Jet Propulsion Laboratory to examine Totten using satellite imagery and aircraft data. The researchers documented for the first time just how much the glacier’s “grounding line” — the critical underwater area where ice, bedrock and the ocean meet — has been retreating inland over the years. The answer is quite a bit. The research found that between 1996 and 2013 Totten’s grounding line retreated as much as 3 kilometers in some places. That’s fast, but it’s not nearly so fast as what has been happening in West Antarctica, where the retreat in some areas has been as much as one to two kilometers per year. “This boundary is very important because that’s where the ice detaches from the bed and becomes afloat and frictionless,” says Li of the grounding line. So any change here is not good news. The researchers were only able to get data for 20 percent of the vast Totten glacier’s grounding line, but this region accounted for 70 percent of the glacier’s current ice loss into the ocean, and for its fastest thinning. A key question thus becomes whether the grounding line in this area could speed up its retreat and in particular, whether a “marine ice sheet instability,” which is thought to exist in West Antarctica, might also exist here. Such an instability is caused by the presence of a “retrograde” or downward-sloping seabed beneath the glacier, which means that warm water can continually get beneath the ice sheet as the grounding line retreats further and further downhill. The answer, the new study suggests, is no. “Immediately upstream of the grounding line there is a 7 kilometer long region — we call it an ice plain because the slopes are really flat, and for this part of the glacier, it could retreat very fast, in a couple of decades or so,” says Li. After that, though, the elevation actually rises for 40 kilometers, and so the retreat would not happen as quickly. “The bedrock topography at the end of the present Totten fjord (beneath the floating thick ice at the glacier front) is such that retreat is likely to proceed rapidly but then slow down,” observes Ted Scambos, lead scientist at the National Snow and Ice Data Center, who reviewed the new study for the Post. “There will be a glacier acceleration and thinning associated with the first retreat into a deep area but then some slowing.” “This is an area harder to destabilize dramatically than in Thwaites area” of West Antarctica, adds Penn State University glaciologist Richard Alley, commenting on the new study. But, he continues, “warming waters can influence this area and access a lot of ice leading to long-term large sea-level rise.” The new study, however, was not able to confirm or refute the existence of the canyon from the earlier paper in Nature Geoscience. There was no data available for the relevant area on the eastern side of the glacier — so this remains a possible route for how warm water may be reaching the glacier’s grounding line. A clear subtext of the new research is that the Thwaites glacier in West Antarctica is a bigger sea level threat than Totten — at least in the short term. But not everyone is so sure that the new research, in its delineation of what the bedrock is like near one key part of the Totten grounding line, does much to lessen concern about the region and its potential for eventually causing large sea level rise. Totten glacier “is super sensitive to that geometry, but it’s also super sensitive to the reorganization of the ocean, and how much heat is delivered,” says Don Blankenship, one of the authors of the Nature Geoscience study and a geoscientist at the University of Texas at Austin. Earlier this year, the Australian Antarctic Division reported ship measurements suggesting that warm ocean water is indeed reaching Totten glacier. In other words, Blankenship agrees with Li that the bedrock topography could temporarily slow down Totten’s retreat. But he thinks the warm ocean is more than powerful enough to overcome such a temporary hindrance over time – and after that, he says, the bedrock slopes down into the deep Aurora Subglacial Basin. Blankenship’s UT Austin colleagues and co-authors Duncan Young and Jamin Greenbaum, meanwhile, have discovered what they say is smaller region of potential marine ice sheet instability near the ocean trench. The grounding line in this area was not mapped in the new study because of a lack of data. Finally, they point to recent research suggesting new mechanisms that can destabilize truly gigantic and mostly submerged glaciers, like Totten, which are rooted well over 1,000 meters below sea level but also have ice extending over 100 meters into the air above sea level. If these glaciers lose their stabilizing ice shelves, the research suggests, then “ice cliff failure” will occur whenever there is a sheer ice face more than 100 meters high above the sea level. Therefore, these researchers say they are still looking at Totten glacier as a potential key to solving one of the most important mysteries in climate research: In past eras of Earth’s history that weren’t all that much warmer than today, scientists believe seas were much, much higher – so much so that not even a collapse of West Antarctica, alone, could account for it. Thus, they’re busy looking for the missing ice – or, the missing ocean water – that will balance these past sea level budgets. And they think Totten and the Aurora basin could be the place that it came from. Clearly, more data gathering will be very important — and will contribute to a continuing reassessment of the long-term vulnerability of East Antarctica, and especially this region. As Tas van Ommen, a senior scientist with the Australia Antarctic Division and also one of the authors of the Nature Geoscience paper, recently wrote: Previously we thought that, aside from a poorly mapped valley far inland of Casey known as Aurora Basin, most of the ice was resting on bedrock hills and mountains above sea level. It turns out that Aurora Basin is very deep and much larger than we thought. More seriously, the basin is connected to the coast by terrain that is extensively below sea level. This makes it much more like West Antarctica, where there is concern that gradual, but irreversible ice loss is underway. The prospect that such a pattern could also impact East Antarctica is a new one, and suggests that changes to the Totten Glacier might be the first stages of such accelerating loss in East Antarctica. Thus, the new research on Totten glacier, in the end, probably has two separate, important messages. First, it reemphasizes that Thwaites glacier, of West Antarctica, is likely the number one place that we should be worried about potentially delivering a lot of sea level rise on a time scale relevant to the people living today, and their children and grandchildren. That’s why Antarctic scientists are clamoring to do vastly more research there — immediately. But beyond Thwaites, there’s the second message. Other parts of Antarctica are also rooted underwater, and therefore vulnerable to warming oceans and recent changes in ocean currents. In the short term, due to their particular configurations, they may be more stable. But in the long term, it’s pretty simple: Heat melts ice. Bleaching and disease are devastating the biggest coral reef in the continental United States Climate change could soon push Persian Gulf temperatures to lethal extremes, report warns Congressional skeptic on global warming demands records from U.S. climate scientists For more, you can sign up for our weekly newsletter here, and follow us on Twitter here.
News Article | December 22, 2016
Not sure if that's footage of aliens or earthlings? This Youtube video by Storyful News offers a rare peak at the marine world below Antarctic sea level. With all kinds of colors and shapes, starfish, wigglies, and pompom-looking things, it's really a world unto itself. Glenn Johnstone, marine biologist with the Australian Antarctic Division, tells us in the video that the footage was shot close to the eastern Antarctic coast, five kilometers from the Casey Research Station and about 3800 kilometers below Perth, Australia. The footage was taken as part of an experiment to look at the effects of ocean acidification, or the perpetual decrease in pH levels of the Earth's oceans. The researchers wanted to see the impacts of acidification on marine fauna, and how it might react to pH levels by the year 2100. Climate change is one of the major threats to global marine systems, said Johnstone, and Antarctica is specifically sensitive to ocean acidification because cold water soaks up more carbon dioxide than water in warmer regions. "Antarctica is where we may see changes due to ocean acidification before we see it around the rest of the world," he said. To get the footage, the researchers deployed a GoPro camera, mounted on top of a remote underwater vehicle, through a hole in the sea ice. The camera was lowered 30 meters below the sheet of ice. At that level, the creatures enjoy a relatively stable environment, with little or no current or wind, due to the protective cap of sea ice sitting over it. The temperature also barely changes all year, so the organisms down there are not adapted as well to environmental changes as are others in more temperate or tropical zones where the temperature range is much broader. And those all those wiggly, squishy, flowy creatures? It's a diverse array down there, according to Johnstone, which includes sea stars, sponges, ascidians, sea cucumbers, worms, sea spiders, and so on. So, while it's not outer space, it might as well be. Get six of our favorite Motherboard stories every day by signing up for our newsletter.
Van Ommen T.D.,Australian Antarctic Division |
Morgan V.,Australian Antarctic Division
Nature Geoscience | Year: 2010
The southwest corner of Western Australia has been subject to a serious drought in recent decades. A range of factors, such as natural variability and changes in land use, ocean temperatures and atmospheric circulation, have been implicated in this drought, but the ultimate cause and the relative importance of the various factors remain unclear. Here we report a significant inverse correlation between the records of precipitation at Law Dome, East Antarctica and southwest Western Australia over the instrumental period, including the most recent decades. This relationship accounts for up to 40% of the variability on interannual to decadal timescales, and seems to be driven by the meridional circulation south of Australia that simultaneously produces a northward flow of relatively cool, dry air to southwest Western Australia and a southward flow of warm, moist air to East Antarctica. This pattern of meridional flow is consistent with some projections of circulation changes arising from anthropogenic climate change. The precipitation anomaly of the past few decades in Law Dome is the largest in 750 years, and lies outside the range of variability for the record as a whole, suggesting that the drought in Western Australia may be similarlyunusual. © 2010 Macmillan Publishers Limited. All rights reserved.
Hunter J.,Australian Antarctic Division
Climatic Change | Year: 2010
Estimation of expected extremes, using combinations of observations and model simulations, is common practice. Many techniques assume that the background statistics are stationary and that the resulting estimates may be used satisfactorily for any time in the future. We are now however in a period of climate change, during which both average values and statistical distributions may change in time. The situation is further complicated by the considerable uncertainty which accompanies the projections of such future change. Any useful technique for the assessment of future risk should combine our knowledge of the present, our best estimate of how the world will change, and the uncertainty in both. A method of combining observations of present sea-level extremes with the (uncertain) projections of sea-level rise during the 21st century is described, using Australian data as an example. The technique makes the assumption that the change of flooding extremes during the 21st century will be dominated by the rise in mean sea level and that the effect of changes in the variability about the mean will be relatively small. The results give engineers, planners and policymakers a way of estimating the probability that a given sea level will be exceeded during any prescribed period during the present century. © Springer Science+Business Media B.V. 2009.
de la Mare W.K.,Australian Antarctic Division
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2014
Catch per unit effort (CPUE) is often the only data available from historical fisheries for inferring distribution and abundance of exploited populations. CPUE underestimates variations in relative abundance when gross effort data are only measured in total operating days. Gross effort includes both searching time and handling time, but only searching time is useful for an index of abundance. A method is developed for estimating searching time by subtracting a maximum likelihood estimate of handling time from the gross effort. An expectation maximization (E-M) algorithm is used to combine maximum likelihood estimates of the handling time with the expected additional operating time due to handling the last catch of each day. Simulation tests show that the estimates of catch per unit of searching time (C/CSW) are much closer to proportionally related to local density than gross CPUE. Estimates of handling time are not unbiased, and some nonlinearity between local density and C/CSW may persist. The methods may be useful for other fisheries where historic gross catch and effort data involve both searching and handling.
Constable A.J.,Australian Antarctic Division
Fish and Fisheries | Year: 2011
The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is widely recognized as a leading international organization in developing best practice in the ecosystem approach to managing fisheries. CCAMLR provides a useful case study for examining the impediments to implementing ecosystem-based fisheries management (EBFM) because it has EBFM principles embedded within its convention rather than having to make a transition from single-species management to an ecosystem approach. CCAMLR is demonstrating that (i) EBFM does not need to equate to complexity in management and (ii) methods can be developed to decide on spatial management strategies for fisheries so that predators of target species are not disproportionately affected as a result of spatial and/or temporal dependencies of predators on their prey. Science has an important role in implementing EBFM, not only in measuring and assessing the status of target species and their predators but also in designing cost-effective management strategies and in resolving disputes. Importantly, attention needs to be given to developing the capability and tools to overcome differences amongst scientists in providing advice to managers. The CCAMLR experience suggests that, without adequate safeguards, voluntary participation by fishing States in CCAMLR and its consensus environment do not provide strong foundations for achieving, in the long term, the ecosystem-based principles for managing fisheries when there is any degree of scientific uncertainty. Some solutions to these issues are discussed. Overall, broader-than-CCAMLR solutions amongst the international community as well as the continued commitment of CCAMLR Members will be required to resolve these issues. © 2011 Blackwell Publishing Ltd.
Wienecke B.,Australian Antarctic Division
Polar Biology | Year: 2012
In 1956, an emperor penguin (Aptenodytes forsteri) colony had been reported during an aerial survey north of the north-western protrusion of the West Ice Shelf in East Antarctica. About 15,000 birds were estimated to be present. The region often has very heavy pack ice conditions hindering access by vessels. In the summers of 2009-2011, we surveyed the area from the air and sighted two emperor penguin colonies. One was situated on top of the ice shelf and comprised 342 adults and 1,156 chicks. The second colony was seen near the northern edge of the West Ice Shelf on the sea ice about 60 km farther south than in 1956. There were at least 1,498 adults and 3,436 chicks. © 2012 Springer-Verlag.
News Article | March 23, 2016
Jennifer Purcell watches intently as the boom of the research ship Skookum slowly eases a 3-metre-long plankton net out of Puget Sound near Olympia, Washington. The marine biologist sports a rain suit, which seems odd for a sunny day in August until the bottom of the net is manoeuvred in her direction, its mesh straining from a load of moon jellyfish (Aurelia aurita). Slime drips from the bulging net, and long tentacles dangle like a scene from an alien horror film. But it does not bother Purcell, a researcher at Western Washington University's marine centre in Anacortes. Pushing up her sleeves, she plunges in her hands and begins to count and measure the messy haul with an assuredness borne from nearly 40 years studying these animals. Most marine scientists do not share her enthusiasm for the creatures. Purcell has spent much of her career locked in a battle to find funding and to convince ocean researchers that jellyfish deserve attention. But she hasn't had much luck. One problem is the challenges that come with trying to study organisms that are more than 95% water and get ripped apart in the nets typically used to collect other marine animals. On top of that, outside the small community of jellyfish researchers, many biologists regard the creatures as a dead end in the food web — sacs of salty water that provide almost no nutrients for predators except specialized ones such as leatherback sea turtles (Dermochelys coriacea), which are adapted to consume jellies in large quantities. “It's been very, very hard to convince fisheries scientists that jellies are important,” says Purcell. But that's starting to change. Among the crew today are two fish biologists from the US National Oceanic and Atmospheric Administration (NOAA) whose research had previously focused on the region's rich salmon stocks. A few years ago, they discovered that salmon prey such as herring and smelt tend to congregate in different areas of the sound from jellyfish1 and they are now trying to understand the ecological factors at work and how they might be affecting stocks of valuable fish species. But first, the researchers need to know how many jellyfish are out there. For this, the team is taking a multipronged approach. They use a seaplane to record the number and location of jellyfish aggregations, or 'smacks', scattered about the sound. And on the research ship, a plankton net has been fitted with an underwater camera to reveal how deep the smacks reach. Correigh Greene, one of the NOAA scientists on board, says that if salmon populations are affected in some way by jellyfish, “then we need to be tracking them”. From the fjords of Norway to the vast open ocean waters of the South Pacific, researchers are taking advantage of new tools and growing concern about marine health to probe more deeply into the roles that jellyfish and other soft-bodied creatures have in the oceans. Initially this was driven by reports of unusually large jellyfish blooms wreaking havoc in Asia, Europe and elsewhere, which triggered fears that jellyfish were taking over the oceans. But mounting evidence is starting to convince some marine ecologists that gelatinous organisms are not as irrelevant as previously presumed. Some studies show that the animals are important consumers of everything from microscopic zooplankton to small fish, others suggest that jellies have value as prey for a wide range of species, including penguins, lobsters and bluefin tuna. There's also evidence that they might enhance the flow of nutrients and energy between the species that live in the sunlit surface waters and those in the impoverished darkness below. “We're all busy looking up at the top of the food chain,” says Andrew Jeffs, a marine biologist at the University of Auckland in New Zealand. “But it's the stuff that fills the bucket and looks like jelly snot that is actually really important in terms of the planet and the way food chains operate.” The animals in question are descendants of some of Earth's oldest multicellular life forms. The earliest known jellyfish fossil dates to more than 550 million years ago, but some researchers estimate that they may have been around for 700 million years, appearing long before fish. They're also surprisingly diverse. Some are tiny filter feeders that can prey on the zooplankton that few other animals can exploit. Others are giant predators with bells up to two metres in diameter and tentacles long enough to wrap around a school bus — three times. Jellyfish belong to the phylum Cnidaria and have stinging cells that are potent enough in some species to kill a human. Some researchers use the term jellyfish, or 'jellies' for short, to refer to all of the squishy forms in the ocean. But others prefer the designation of 'gelatinous zooplankton' because it reflects the amazing diversity among these animals that sit in many different phyla: some species are closer on the tree of life to humans than they are to other jellies. Either way, the common classification exists mainly for one dominant shared feature — a body plan that is based largely on water. This structure can make gelatinous organisms hard to see. Many are also inaccessible, living far out at sea or deep below the light zone. They often live in scattered aggregations that are prone to dramatic population swings, making them difficult to census. Lacking hard parts, they're extremely fragile. “It's hard to find jellyfish in the guts of predators,” says Purcell. “They're digested very fast and they turn to mush soon after they're eaten.” For most marine biologists, running into a mass of jellyfish is nothing but trouble because their collection nets get choked with slime. “It's not just that we overlooked them,” says Jonathan Houghton at Queen's University Belfast, UK. “We actively avoided them.” But over the past decade and a half, jellyfish have become increasingly difficult to ignore. Enormous blooms along the Mediterranean coast, a frequent summer occurrence since 2003, have forced beaches to close and left thousands of bathers nursing painful stings. In 2007, venomous jellyfish drifted into a salmon farm in Northern Ireland, killing its entire stock of 100,000 fish. On several occasions, nuclear power plants have temporarily shut down operations owing to jelly-clogged intake pipes. The news spurred scientists to take a closer look at the creatures. Marine biologist Luis Cardona at the University of Barcelona in Spain had been studying mostly sea turtles and sea lions. But around 2006, he shifted some of his attention to jellyfish after large summer blooms of mauve stingers (Pelagia noctiluca) had become a recurring problem for Spain's beach-goers. Cardona was particularly concerned by speculation that the jellyfish were on the rampage because overfishing had reduced the number of predators. “That idea didn't have very good scientific support,” he says. “But it was what people and politicians were basing their decisions on, so I decided to look into it.” For this he turned to stable-isotope analysis, a technique that uses the chemical fingerprint of carbon and nitrogen in the tissue of animals to tell what they have eaten. When Cardona's team analysed 20 species of predator and 13 potential prey, it was surprised to find that jellies had a major role in the diets of bluefin tuna (Thunnus thynnus), little tunny (Euthynnus alletteratus) and spearfish (Tetrapturus belone)2. In the case of juvenile bluefins, jellyfish and other gelatinous animals represented up to 80% of the total food intake. “According to our models they are probably one of the most important prey for juvenile bluefin tuna,” says Cardona. Some researchers have challenged the findings, arguing that stable-isotope results can't always distinguish between prey that have similar diets — jellyfish and krill both eat phytoplankton, for instance. “I'm sure it's not true,” Purcell says of the diet analysis. Fast-moving fish, she says, “have the highest energy requirements of anything that's out there. They need fish to eat — something high quality, high calorie.” But Cardona stands by the results, pointing out that stomach-content analyses on fish such as tuna have found jellyfish, but not krill. What's more, he conducted a different diet study3 that used fatty acids as a signature, which supported his earlier results on jellyfish, he says. “They're probably playing a more relevant role in the pelagic ecosystem of the western Mediterranean than we originally thought.” Researchers are reaching the same conclusion elsewhere in the world. On an expedition to Antarctica in 2010–11, molecular ecologist Simon Jarman gathered nearly 400 scat samples to get a better picture of the diet of Adélie penguins (Pygoscelis adeliae), a species thought to be threatened by global warming. Jarman, who works at the Australian Antarctic Division in Kingston, reported in 2013 that DNA analysis of the samples revealed that jellyfish are a common part of the penguin's diet4. Work that has yet to be published suggests the same is true for other Southern Ocean seabirds. “Albatrosses, gentoo penguins, king penguins, macaroni and rockhopper penguins — all of them eat jellyfish to some extent,” says Jarman (see 'Lean cuisine'). “Even though jellyfish may not be the most calorifically important food source in any area, they're everywhere in the ocean and they're contributing something to many top-level predators.” And some parts of jellyfish hold more calories than others. Fish have been observed eating only the gonads of reproductive-stage jellyfish, suggesting a knack for zeroing in on the most energy-rich tissues. Through DNA analyses, researchers are also discovering more about how jellyfish function as refuges in the open ocean. Scientists have long known that small fish, crustaceans and a wide range of other animals latch on to jellyfish to get free rides. But in the past few years, it has become clear that the hitchhikers also dine on their transport. In the deep waters of the South Pacific and Indian oceans, Jeffs has been studying the elusive early life stages of the spiny lobster (Panulirus cygnus). During a 2011 plankton-collecting expedition 350 kilometres off the coast of Western Australia, he and his fellow researchers hauled in a large salp (Thetys vagina), a common barrel-shaped gelatinous animal. The catch also included dozens of lobster larvae, including six that were embedded in the salp itself. DNA analysis of the lobsters' stomach glands revealed that the larvae had been feeding on their hosts5. Jeffs now suspects that these crustaceans, which support a global fishery worth around US$2 billion a year, depend heavily on this relationship. “What makes the larvae so successful in the open ocean,” he says, “is that they can cling to what is basically a big piece of floating meat, like a jellyfish or a big salp, and feed on it for a couple of weeks without exerting any energy at all.” Researchers are starting to recognize that jellyfish are important for other reasons, such as transferring nutrients from one part of the ocean to another. Biological oceanographer Andrew Sweetman at the International Research Institute of Stavanger in Norway has seen this in his studies of 'jelly falls', a term coined to describe what happens when blooms crash and a large number of dead jellies sink rapidly to the sea floor. In November 2010, Sweetman began to periodically lower a camera rig 400 metres to the bottom of Lurefjorden in southwestern Norway to track the fate of this fjord's dense population of jellyfish6. Previous observations from elsewhere had suggested that dead jellies pile up and rot, lowering oxygen levels and creating toxic conditions. But Sweetman was surprised to find almost no dead jellies on the sea floor. “It didn't make sense.” He worked out what was happening in 2012, when he returned to the fjord and lowered traps baited with dead jellyfish and rigged with video cameras. The footage from the bottom of the fjord showed scavengers rapidly consuming the jellies. “We had just assumed that nothing was going to be eating them,” he says. Back on land, Sweetman calculated7 that jelly falls increased the amount of nitrogen reaching the bottom by as much as 160%. That energy is going back into the food web instead of getting lost through decay, as researchers had thought. He's since found similar results using remotely operated vehicles at much greater depths in remote parts of the Pacific Ocean. “It's overturning the paradigm that jellyfish are dead ends in the food web,” says Sweetman. Such discoveries have elicited mixed responses. For Richard Brodeur, a NOAA fisheries biologist based in Newport, Oregon, the latest findings do not change the fact that fish and tiny crustaceans such as krill are the main nutrient source for most of the species that are valued by humans. If jellyfish are important, he argues, it is in the impact they can have as competitors and predators when their numbers get out of control. In one of his current studies, he's found that commercially valuable salmon species such as coho (Oncorhynchus kisutch) and Chinook (Oncorhynchus tshawytscha) that are caught where jellyfish are abundant have less food in their stomachs compared with those taken from where jellies are rare, suggesting that jellyfish may have negative impacts on key fish species. “If you want fish resources,” he says, “having a lot of jellyfish is probably not going to help.” But other researchers see the latest findings as reason to temper the growing vilification of jellyfish. In a 2013 book chapter8, Houghton and his three co-authors emphasized the positive side of jellies in response to what they saw as “the flippant manner in which wholesale removal of jellyfish from marine systems is discussed”. As scientists gather more data, they hope to get a better sense of exactly what role jellyfish have in various ocean regions. If jellies turn out to be as important as some data now suggest, the population spikes that have made the headlines in the past decade could have much wider repercussions than previously imagined. Back in Puget Sound, Greene is using a camera installed on a net to gather census data on a jellyfish smack. He watches video from the netcam as it slowly descends through a dense mass of creamy white spheres. At a depth of around 10 metres, the jelly curtain finally begins to thin out. Later, Greene makes a crude estimate. “Two point five to three million,” he says, before adding after a brief pause, “that's a lot of jellyfish.” A more careful count will come later. Right now there's plenty of slime to be hosed off the back deck. Once that's taken care of, the ship's engines come to life. The next jellyfish patch awaits.
News Article | December 21, 2016
Antarctica may look like a forbidding white expanse, but life below the sea ice is full of colour. Scientists from the Australian Antarctic Division sent a robot down to take a look, capturing a small forest of underwater organisms in bright purples, yellows and pinks. The Remotely Operated Vehicle (ROV) was submerged at O'Brien Bay in east Antarctica. According to biologist Glenn Johnstone, the organisms survive in water that is -1.5 degrees Celsius (29.3 degrees Fahrenheit) and covered in thick sea ice for most of the year. "This footage reveals a habitat that is productive, colourful, dynamic and full of a wide variety of biodiversity, including sponges, sea spiders, urchins, sea cucumbers and sea stars," he said in a statement. The research team was collecting data about sea water acidity, salinity and temperature to help them understand how the region will be affected by climate change, particularly ocean acidification. "Antarctica may be one of the first places we see detrimental effects of ocean acidification on these organisms," Johnstone added. The gloves come off: 'Rogue One' debate gets heated 'Poop the Potato' game is here to save you from the holidays Conquer yourself in this exhilarating DreamHack Masters trailer