New study finds Alaskans familiar with ocean acidification, not aware of risks to fisheries

New research published in Marine Policy from the first Alaska-focused study on public understanding and awareness of ocean acidification risk shows that Alaskans are three times more aware of ocean acidification than Americans in general.  However, Alaskans have difficulty seeing ocean acidification as an immediate risk, and the direct risks to Alaska’s fisheries are still not well understood. The research, “Gauging perceptions of ocean acidification in Alaska,” can be read online.

In Alaska, the impacts of ocean acidification have the potential to be even worse than “other coastal communities because of an accelerated rate of change in ocean chemistry, and statewide reliance on commercial and subsistence fishing. Accurately evaluating ocean acidification risk directly influences the ability to respond to change. The research builds on earlier NOAA-led research showing that communities in southeast and southwest Alaska are more at risk than other areas of the state because of their heavy reliance on fisheries expected to be impacted by ocean acidification.

“We wanted to learn the best way to provide Alaskans with the information they need to properly respond to ocean acidification,” said Lauren Frisch, who led the study and is a research associate at the University of Alaska Fairbanks Ocean Acidification Research Center. “The first step was to determine where there are gaps in the understanding of ocean acidification so that we can then work to fill them in.”

                      Crab fishing
A new study shows that Alaskans know about ocean acidification, but are not aware of the risk it poses to Alaskan fisheries. (NOAA)

Some 2000 Alaskans received a questionnaire in September, 2013. Questionnaires asked about each respondent’s role in the state's fishing industry as well as their belief in, understanding of, and concern about ocean acidification. The questionnaire’s response rate was 18 percent, which is high for studies of this nature. Results showed limited understanding of how Alaska will be uniquely impacted by ocean acidification. For example, only 28 percent of Alaskans believe that ocean acidification would have a greater impact on Alaska than other states in the United States.  Alaskans affiliated with the state’s fishing industry are not significantly more concerned about ocean acidification than those unaffiliated, and only 33 percent believe that ocean acidification will decrease revenue for fisheries. Finally, ocean acidification is perceived as a distant risk.  

“It can be difficult to think about ocean acidification as an immediate risk with all of the other challenges that we’re facing,” said Jeremy Mathis, who is the co-lead author on the paper describing the study’s results and an oceanographer at NOAA’s Pacific Marine Environmental Laboratory. “We really have to work harder to get the message out to stakeholders around Alaska that ocean acidification is something that they need to consider sooner rather than later.”

With a better idea of what Alaskans understand about this issue, the next step is to shape public education in a way that facilitates a long-term discussion of ocean acidification drivers and impacts, as well as mitigation and adaptation strategies.

“Moving forward, we need to figure out how to enhance this understanding that acidification is not uniform, and therefore adaptation plans will be more successful if they are local.  Educating communities with local examples about their specific risk could help foster this understanding.  The best thing we can do is provide vulnerable communities the toolset to evaluate risk themselves,” said Frisch.

Source: NOAA

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Mass animal die-offs may be increasing, new research shows

Large numbers of dead sunfish and largemouth bass in April 2014 following a severe winter on Wintergreen Lake, Kalamazoo County, Michigan. (Photo courtesy of G. Mittelbach)

Mass die-offs of animals may be increasing in frequency and — for birds, fishes, and marine invertebrates — in severity as well, according to a study of 727 mass mortality events since 1940.

Despite the ecological importance of individual mass mortality events, in which a larger than normal number of individuals die within a population, little research has been conducted on patterns across mass mortality events. The new study will help researchers better assess trends in mass mortality events and their causes, according to the authors of the paper in the Jan. 12 issue of the Proceedings of the National Academy of Sciences.

“The initial patterns are surprising, in terms of the documented changes to frequencies of occurrences, magnitudes of each event, and the causes of mass mortality,” said Samuel Fey, a postdoctoral fellow in the Department of Ecology and Evolutionary Biology at Yale and co-lead author of the paper. “These data also show that we have a lot of room to improve how we document and study these types of rare events.”

Fey, along with fellow researchers at the University of San Diego and University of California-Berkeley, report that the magnitude of the die-offs has increased in birds, fishes, and marine invertebrates, held steady among mammals, and decreased in frogs and amphibians. The authors recognized that more scientific research has been done on mass mortality events in the last few decades but said even accounting for this “discovery bias” does not explain all of the increase in such events. The increase in mass mortality events appears to be associated with a rise in disease emergence, biotoxicity, and multiple interacting stressors, they note.

Overall, disease was the primary culprit, accounting for 26% of the mass die-offs. The impacts of direct human activity, primarily from environmental contamination, caused 19% of such events. Another major cause was biotoxicity triggered by events such as algae blooms, rapid increases of algae in water systems. Processes directly influenced by climate — such as weather extremes, thermal stress, oxygen stress, or starvation — also contributed accounted collectively for about 25% of mass mortality events.

The most severe events were those with multiple causes, the paper shows.

“This study should improve our understanding of the continuum of mortality patterns and processes that exist between background mortality levels and species-level extinctions,” Fey said.

Adam M. Siepielski of the University of San Diego was co-lead author of the paper. Stephanie M. Carlson of the University of California-Berkeley was senior author. Fey began working on this research while a graduate student at Dartmouth College.

Source: Yale University

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Cone snail venom holds promise for medical treatments for cancer, addiction

Professor Frank Marí in the Charles E. Schmidt College of Science at Florida Atlantic University holds a live Conus regius, a particular species of cone snail collected by the Marí group at the Florida Keys. Credit: Professor Anton Oleinik

While considered a delicacy in some parts of the world, snails have found a more intriguing use to scientists and the medical profession offering a plethora of research possibilities. Cone snails are marine mollusks, just as conch, octopi and squid, but they capture their prey using venom. The venom of these marine critters provides leads for detection and possible treatment of some cancers and addictions.

Frank Marí, Ph.D., professor in the Department of Chemistry and Biochemistry in FAU's Charles E. Schmidt College of Science at Florida Atlantic University, has focused his research on cone snail venom and has published a study in the current issue of the Journal of Biological Chemistry.

"The venom produced by these animals immobilizes prey, which can be worms, other snails and fish," said Marí. "The venom is an extraordinary complex mixture of compounds with medicinal properties."

The venom components selectively target cells in the body and make them valuable drug leads and powerful molecular tools for understanding the human body's processes. One class of venom components is the alpha-conotoxins, named so because they target nicotinic receptors that are central to a range of diseases such as Alzheimer's disease, schizophrenia, tobacco addiction and lung cancer.

The venom of a particular species of cone snail, Conus regius, collected by the Marí group at the Florida Keys, is particularly rich in alpha conotoxins. Aldo Franco, Ph.D., who worked in Marí's lab, described more than ten new alpha-conotoxins in his Ph.D. dissertation at FAU. 

Among these, they found RegIIA, a compound that potently blocked the alpha3beta4 nicotinic receptor. This particular receptor when activated can be associated with lung cancer and nicotine addiction.

"We investigated in detail how RegIIA interacts with the alpha3beta4 nicotinic receptors and embarked on engineering new compounds that were more specific toward alpha3beta4 receptors and not other nicotinic receptors," said Marí. "Our aim is to open new avenues for cancer and addiction research inspired on compounds from marine animals."

Cone snails can be found throughout the Florida coast at different depths. Marí and his team regularly collect these animals using SCUBA and sometimes using deep-water submarines.

Source: Florida Atlantic University

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The science behind swimming: From whales to larvae, common principles at work in swimming

Whale and diver (stock illustration). Using simple hydrodynamics, researchers were able to show that a handful of principles govern how virtually every animal -- from the tiniest fish to birds to gigantic whales propel themselves though the water. Credit: © James Thew / Fotolia

At nearly 100 feet long and weighing as much as 170 tons, the blue whale is the largest creature on the planet, and by far the heaviest living thing ever seen on Earth. So there's no way it could have anything in common with the tiniest fish larvae, which measure millimeters in length and tip the scales at a fraction of a gram, right?

Not so fast, says L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, of Organismic and Evolutionary Biology, and of Physics.

Using simple hydrodynamics, a team of researchers led by Mahadevan was able to show that a handful of principles govern how virtually every animal -- from the tiniest fish to birds to gigantic whales propel themselves though the water. The study is described in a September 14 paper in Nature Physics.

"What we wanted to investigate was how the speed of an organism changes as a function of how large it is, how quickly it moves and how much it moves," Mahadevan said. "To resolve that in detail, however, is very complex, because there is a great deal of differences in morphology and what parts of the body different creatures use to swim. The question is: Is there anything in common across all these organisms? The answer, we found, is yes."

In an effort to uncover those common principles, Mahadevan working with a postdoctoral fellow in his group , Mattia Gazzola, and a colleague Mederic Argentina from the University of Nice, began by trying to unpack the physics of how different creatures swim.

"The traditional approach to swimming phenomena is to take a certain specimen and accurately characterize it via experiments and/or simulations, and try to generalize from there, but it is very hard to strip out specific biological effects from general principles," Gazzola said. "We instead thought that while swimmers exhibit a huge diversity in shapes and kinematics, at the end of the day they all live in the same media, water.

"Therefore we thought that if a unifying mechanistic principle existed, it had to lie in the constraints that the flow environment poses to all its inhabitants," he continued. "And this is a purely physical problem, much easier to solve since it is not affected by biological vagaries. What I like about this paper is that in one line of algebra we derived a compact formula that accounts for 50 years of experiments. This is an example of how powerful minimal modeling can be."

"The basic relationship we wanted to understand was how the input variables -- namely the size of the organism, the amount an organism moves and how quickly it moves -- control the output variable, which is effectively the speed at which it moves," Mahadevan explained. "What we found is that there is a specific relationship, which can be described by in terms of a simple scaling law with two limits."

The first, which corresponds to creatures moving at intermediate speeds, describes situations where the bulk of the resistance is caused by skin friction, because water "sticks" to the organism's body. At faster speeds, Mahadevan said, the resistance organisms face largely comes from pressure that builds up in front of and around them, which is described by the second limit.

"While it wasn't a surprise that the resistance changed at organisms moved faster, the fact that those challenges could be so simply described was interesting and provocative, because we are talking about organisms that range in size from a few millimeters to the size of a blue whale," Mahadevan said.

Armed with those observations, Mahadevan and colleagues turned to a host of empirical observations that had been made over the past 50-plus years. When those data were plotted on a graph, the researchers found that the swimming speed of virtually every organism, from fish larvae to frogs to birds, amphibians and even whales, could be described by one of the two equations.

The same also held true, Mahadevan said, when Gazzola created complex computer models to solve the governing equations of fluid dynamics to describe how different organisms swim.

"What is particularly interesting is that all the organisms essentially reach the hydrodynamic limits of performance," he said. "Our simple theory, which doesn't distinguish in any detailed way between something like a blue whale and fish larvae, except in the parameters of how large you are, much you move and how quickly you move, can describe all this diversity. That suggests there are general principles at work here."


Source: Harvard University

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Ancient Europeans intolerant to lactose for 5,000 years after they adopted agriculture

Milk

By analysing DNA extracted from the petrous bones of skulls of ancient Europeans, scientists have identified that these peoples remained intolerant to lactose (natural sugar in the milk of mammals) for 5,000 years after they adopted agricultural practices and 4,000 years after the onset of cheese-making among Central European Neolithic farmers.

The findings published online in the scientific journal Nature Communications (21 Oct) also suggest that major technological transitions in Central Europe between the Neolithic, Bronze Age and Iron Age were also associated with major changes in the genetics of these populations.

For the study, the international team of scientists examined nuclear ancient DNA extracted from thirteen individuals from burials from archaeological sites located in the Great Hungarian Plain, an area known to have been at the crossroads of major cultural transformations that shaped European prehistory. The skeletons sampled date from 5,700 BC (Early Neolithic) to 800 BC (Iron Age).

It took several years of experimentation with different bones of varying density and DNA preservation for the scientists to discover that the inner ear region of the petrous bone in the skull, which is the hardest bone and well protected from damage, is ideal for ancient DNA analysis in humans and any other mammals.

According to Professor Ron Pinhasi from the UCD Earth Institute and UCD School of Archaeology, University College Dublin, the joint senior author on the paper, "the high percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold. This gave us anywhere between 12% and almost 90% human DNA in our samples compared to somewhere between 0% and 20% obtained from teeth, fingers and rib bones."

For the first time, these exceptionally high percentage DNA yields from ancient remains made it possible for scientists to systematically analyse a series of skeletons from the same region and check for known genetic markers including lactose intolerance.

"Our findings show progression towards lighter skin pigmentation as hunter and gatherers and non-local farmers intermarried, but surprisingly no presence of increased lactose persistence or tolerance to lactose" adds Professor Pinhasi.

"This means that these ancient Europeans would have had domesticated animals like cows, goats and sheep, but they would not yet have genetically developed a tolerance for drinking large quantities of milk from mammals," he says.

According to Professor Dan Bradley from the Smurfit Institute of Genetics, Trinity College Dublin, co-senior author on the paper, "our results also imply that the great changes in prehistoric technology including the adoption of farming, followed by the first use of the hard metals, bronze and then iron, were each associated with the substantial influx of new people. We can no longer believe these fundamental innovations were simply absorbed by existing populations in a sort of cultural osmosis."

Source: University College Dublin

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Tailor-made for the aquaculture sector

Details are important. The hood is specially adapted for personnel wearing helmets – without compromising vision. Credit: SINTEF Health Research

Fish husbandry workers have played an active part in developing work clothing tailor-made for their wet, windy and messy working conditions.

They're standing in a small circle around a net pen out in the ocean. Their job is to maintain the net pens, de-louse the salmon, and carry out the many other tasks essential to the running of a fish farm facility. The wind is bitter and the rain is lashing in from all directions. Sea water is splashing around their feet. Everything they handle is wet. Cold water creeps relentlessly up to their knees and along to their elbows inside their coveralls, which are only waterproof up until the second wash.

This is a normal working day for a couple of thousand workers in fish farms all along the Norwegian coast. In spite of this no work clothing exists that is specifically adapted to their very special working conditions. Yet.

Industrial designers Tore Christian Bjørsvik Storholmen and Ole Petter Næsgaard at SINTEF Health Research have developed work clothing which they hope will make conditions both safer and more comfortable for husbandry workers out on the fish farms. Their project has been carried out in close collaboration with the workers who will be wearing the clothing.

Better together

"We've spent a lot of time getting to know the business and the needs of the husbandry workers," says Næsgaard. "We've taken part in many tasks, observed what goes on, and have obtained input and feedback in response to our suggestions," he says. "We've met with a thoroughly honest group of people. They don't hold back when they're not satisfied," he says.

They visited three different facilities close to Hitra and Frøya as part of a pilot project. Ideas and sketches made during one visit were taken to the next so that they could encourage reactions and get feedback. It has been an iterative process involving an ongoing series of corrections and improvements.

"This has served as a quality control on our work to develop relevant and attractive solutions," says Storholmen. "We could never have put the first prototype on the market," he says. "But our dialogue with the users has enabled continuous refinement. New details are always being developed and incorporated. "We're now getting close to a product that can be introduced to the market," he says.

Inspired by climbers and skiers

"When we were studying the husbandry workers, we saw that they do a lot of climbing from boat to boat through ropes and cables and across a variety of different barriers. This led us to obtain inspiration from clothes developed for climbers. The result is that the clothing now offers a very good fit - combined with excellent freedom of movement," explains Storholmen.

When it comes to choosing fabrics, the researchers have obtained greater inspiration from sports clothes than from other types of work clothing. Instead of thick, insulated suits, the new clothing concept has much more in common with kit worn by skiers.

"We've exploited the shell principle," says Storholmen. "The fabric of the outermost layer is water- and wind-proof and very light and durable," he says. "We've also developed intermediate layers and underwear, so users can select the clothing they need based on weather conditions and their own level of activity," he explains.

The clothing is also specifically adapted to allow good freedom of movement in the neck area - even when wearing a life vest. The same applies to the hood which has plenty of room for the mandatory helmet. What about reflective patches? These are placed strategically on the arms, hood and shoulders, and not across the shoulders and legs which is standard for the majority of existing work clothing.

"Actually, we saw that workers testing the clothing were at first sorry to have to return it following the tests," says Storholmen. "This has to be a good sign," he says.

However, the developers are not satisfied simply with anatomical adjustments, new fabrics and good visibility. There has to be a place for modern technology in this type of clothing. So the suit is equipped with a waterproof pocket for a mobile phone, and will also be fitted with a separate pocket to accommodate a man-overboard alarm.

Comfort equals effective HSE

The fish farms visited by the researchers are in exposed coastal locations, often about a half-hour's boat trip from land. The husbandry workers are housed in floating pontoons, surrounded by net pens. They may have to stay here for as much as a week at a time. There have been situations where workers have fallen into the sea. It is essential that the new work clothing represents an improvement in safety. It must be easy for the wearer to get hold of important tools such as knives, tape and communications equipment.

"An Operations Manager told us that good work clothing is one of the most important aids to effective HSE," says Storholmen. "People standing around getting cold lose concentration on what they're doing, making accidents more likely. We believe that this is thoroughly addressed by the new clothing," he says.

A net pen is an enormous "warehouse," and if a major accident occurs, the consequences for the environment and the company's profitability may be very large.

"Aquaculture uniform"

The clothing currently worn by husbandry workers is essentially the same as the standard primarily developed for the building and construction industry, where competitive pricing is a major issue. The clothing being developed in this project will probably be more expensive.

"Current work clothing is a consumer item," say the researchers. "Our impression is that there is a willingness to pay for a better and more durable product specifically adapted to the needs of the aquaculture industry - a specially designed "aquaculture uniform" which can identify the workers and promote an increase in the pride they have in their profession," they say.

Source: SINTEF

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Electric eels deliver taser-like shocks

News research has discovered that the electric eel delivers Taser-like shocks. Credit: Kenneth Catania, Vanderbilt University

The electric eel -- the scaleless Amazonian fish that can deliver an electrical jolt strong enough to knock down a full-grown horse -- possesses an electroshock system uncannily similar to a Taser.

That is the conclusion of a nine-month study of the way in which the electric eel uses high-voltage electrical discharges to locate and incapacitate its prey. The research was conducted by Vanderbilt University Stevenson Professor of Biological Sciences Kenneth Catania and is described in the article "The shocking predatory strike of the electric eel" published in the Dec. 5 issue of the journal Science.

People have known about electric fish for a long time. The ancient Egyptians used an electric marine ray to treat epilepsy. Michael Faraday used eels to investigate the nature of electricity and eel anatomy helped inspire Volta to create the first battery. Biologists have determined that a six-foot electric eel can generate about 600 volts of electricity -- five times that of a U.S. electrical outlet. This summer scientists at the University of Wisconsin-Madison announced that they had sequenced the complete electric eel genome.

Until now, however, no one had figured out how the eel's electroshock system actually worked. In order to do so, Catania equipped a large aquarium with a system that can detect the eel's electric signals and obtained several eels, ranging up to four feet in length.

As he began observing the eels' behavior, the biologist discovered that their movements are incredibly fast. They can strike and swallow a worm or small fish in about a tenth of a second. So Catania rigged up a high-speed video system that ran at a thousand frames per second so he could study the eel's actions in slow motion.

Catania recorded three different kinds of electrical discharges from the eels: low-voltage pulses for sensing their environment; short sequences of two or three high-voltage millisecond pulses (called doublets or triplets) given off while hunting; and volleys of high-voltage, high-frequency pulses when capturing prey or defending themselves from attack.

He found that the eel begins its attack on free-swimming prey with a high-frequency volley of high-voltage pulses about 10 to 15 milliseconds before it strikes. In the high-speed video, it became apparent that the fish were completely immobilized within three to four milliseconds after the volley hit them. The paralysis was temporary: If the eel didn't immediately capture a fish, it normally regained its mobility after a short period and swam away.

"It's amazing. The eel can totally inactivate its prey in just three milliseconds. The fish are completely paralyzed," said Catania.

These observations raised an obvious question: How do the eels do it? For that, there was no clear answer in the scientific literature.

"I have some friends in law enforcement, so I was familiar with how a Taser works," said Catania. "And I was struck by the similarity between the eel's volley and a Taser discharge. A Taser delivers 19 high-voltage pulses per second while the electric eel produces 400 pulses per second."

The Taser works by overwhelming the nerves that control the muscles in the target's body, causing the muscles to involuntarily contract. To determine if the eel's electrical discharge had the same effect, Catania walled off part of the aquarium with an electrically permeable barrier. He placed a pithed fish on other side of the barrier from the eel and then fed the eel some earthworms, which triggered its electrical volleys. The volleys that passed through the barrier and struck the fish produced strong muscle contractions.

To determine whether the discharges were acting on the prey's motor neurons -- the nerves that control the muscles -- or on the muscles themselves, he placed two pithed fish behind the barrier: one injected with saline solution and other injected with curare, a paralytic agent that targets the nervous system. The muscles of the fish with the saline continued to contract in response to the eel's electrical discharges but the muscle contractions in the fish given the curare disappeared as the drug took effect. This demonstrated that the eel's electrical discharges were acting through the motor neurons just like Taser discharges.

Next Catania turned his attention to the way in which the eel uses electrical signals for hunting. The eel is nocturnal and doesn't have very good eyesight. So it needs other ways to detect hidden prey.

The biologist determined that the closely space doublets and triplets that the eel emits correspond to the electric signal that motor neurons send to muscles to produce an extremely rapid contraction.

"Normally, you or I or any other animal can't cause all of the muscles in our body to contract at the same time. However, that is just what the eel can cause with this signal," Catania said.
Putting together the fact that the eels are extremely sensitive to water movements with the fact that the whole-body muscle contraction causes the prey's body to twitch, creating water movements that the eel can sense, Catania concluded that the eel is using these signals to locate hidden prey.

To test this hypothesis, Catania connected a pithed fish to a stimulator.. He put the fish in a clear plastic bag to protect it from the eel's emissions. He found that when he stimulated the fish to twitch right after the eel emitted one of its signals, the eel would attack. But, when the fish failed to respond to its signal, the eel did not attack. The result supports the idea that the eel uses its electroshock system to force its prey to reveal their location.

"If you take a step back and think about it, what the eel can do is extremely remarkable," said Catania. "It can use its electrical system to take remote control of its prey's body. If a fish is hiding nearby, the eel can force it to twitch, giving away its location, and if the eel is ready to capture a fish, it can paralyze it so it can't escape."

The research was funded by a Pradel Award from the National Academy of Sciences, a Guggenheim fellowship and National Science Foundation grant 0844743.

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Source: Vanderbilt University

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Trade winds ventilate the tropical oceans: Explanation for increasing oxygen deficiency

Scheme of the tropical Pacific: Strong growth of plankton (1) leads to a high oxygen consumption and extended oxygen minimum zones (2). Ocean currents (3) at a few hundred meters depth provide an influx of oxygenated water from the subtropics (4). Fluctuations of the trade winds (5) influence the strength of these currents. Credit: Graphics: Claus Böning, Markus Scheinert, GEOMAR

Long-term observations indicate that the oxygen minimum zones in the tropical oceans have expanded in recent decades. The reason is still unknown. Now scientists at the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Collaborative Research Centre 754 "Climate -- Biogeochemical Interactions in the Tropical Ocean" have found an explanation with the help of model simulations: a natural fluctuation of the trade winds. The study has been published in the international journal Geophysical Research Letters.

The changes can be measured, but their reasons were unknown. For several decades, scientists have carefully observed that the oxygen minimum zones (OMZ) in the tropical oceans are expanding. These zones are a paradise for some specially adapted microorganisms, but for all larger marine organisms such as fish and marine mammals they are uninhabitable. Thus, their expansion has already narrowed down the habitat of some fish species.

Marine scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Kiel Collaborative Research Centre (Sonderforschungsbereich, SFB) 754 "Climate -- Biogeochemical Interactions in the Tropical Ocean" now have found a possible reason for these changes by using a model simulation of climate and biological processes. As their study shows, the trade winds north and south of the Equator play a crucial role in the supply of oxygen to tropical sea water. "So fluctuations in the trade winds could also be responsible for the observed enlargement of the oxygen minimum zones in recent years," explains Dr. Olaf Duteil, lead author of the study, which has now been published in the international journal Geophysical Research Letters.

OMZs exist in different intensities at the eastern edges of all tropical oceans. Because nutrient-rich water from the depths reaches the surface in these areas plankton thrives particularly well. Therefore large amounts of plankton organisms die there, too. After their death they sink down to the ocean floor. On the way down bacteria start to decompose the biomass. In doing so they consume the oxygen. The largest of these OMZs stretches from the coasts of Chile and Peru far into the Pacific ocean.

At the same time currents at a few hundred meters depth transport oxygen-rich water from the subtropics towards the tropics, where the oxygen minimum zones lie. "One can think of the tropical Pacific Ocean as a bathtub. When I open the tap, I fill the bathtub with water or 'oxygen', respectively. When the siphon is open, too, we lose oxygen at the same time. We then have an instable equilibrium between input and output," explains Dr. Duteil, "If I turn off the tap a little, the tub empties slowly."

As the researchers were able to determine in a computer simulation of the oxygen balance now, the strength of the currents and thus the oxygen flow to the tropics is directly related to the strength of the trade winds. "It is well known that they vary on a decadal time scale," says co-author Prof. Dr. Claus Böning from GEOMAR, "but these variations haven never been investigated in relation to the oxygen budget of tropical oceans. "

Since the trade winds have been in a weak phase since the mid-1970s, this could be the explanation for the observed enlargement of the oxygen minimum zones. "The oxygen bathtub of the tropical oceans is emptying," says Dr. Duteil. Once the trade winds come back into a stronger phase, the process will be reversed.

This does not mean that external processes such as the general global warming have no influence on the oxygen concentrations in the tropical oceans. "There is evidence that global change affects the major wind systems of the Earth. That would have a direct impact on the oxygen transport in the subtropical and tropical ocean," explains Prof. Andreas Oschlies, co-author and speaker of the SFB 754. "But it is important that according to this study the trade winds in any case as must be considered as a factor for long-term development of tropical oxygen minimum zones," Oschlies adds.

Source: Helmholtz Centre for Ocean Research Kiel (GEOMAR)

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Microplastics in the ocean: Biologists study effects on marine animals

A marine isopod of the genus Idotea with food pellets.
Credit: Photo Alfred Wegener Institute / Julia Hämer

Ingestion of microplastic particles does not mechanically affect marine isopods. This was the result of a study by biologists at the North Sea Office of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) that was published recently in the journal Environmental Science and Technology. The study marks the launch of a series of investigations aimed at forming a risk matrix on the sensitivity of different marine species to microplastic pollution.

Uptake of large plastic items by birds and fish may cause blockage of the gastrointestinal tract and severe starvation of the animals. "We were wondering whether small plastic particles have a comparable effect on smaller animals," says Dr. Lars Gutow from AWI's North Sea Office. "Only very limited research has been done on the effects of microplastics on living beings. Accordingly, there is great uncertainty about the implications for marine animals," the biologist explains the motivation for the study.

Lars Gutow and his colleagues selected the isopod Idotea emarginata as their model organism for an initial case study. In feeding experiments the researchers offered the isopods artificial algal food supplemented with plastic particles. The food contained three different kinds of microplastics in varying concentrations. They used industrially produced polystyrene particles with a diameter of ten micrometers as well as self-made fragments and fibres made of polyethylene and polyacryl, respectively.

The researchers studied the fate of the different materials under a light microscope, with the help of a fluorescence microscope, and with an electron microscope. They were able to trace the path of the microplastic particles through the isopods and determine the concentrations of the particles in different sections of the digestive system. The study showed that the concentration of microplastics in the faecal material of the isopods was as high as in the food. The scientists found small amounts of microplastics both in the stomach and in the gut of the animals. However, they did not detect any microparticles in the digestive glands. "The isopods ingested and excreted the artificial food with the microplastic particles without absorbing or accumulating the particles," Gutow summarises the results. Thus, plastic particles in the specific size range studied do not represent a direct mechanical risk for isopods and probably not for other crustaceans either. "In the case of Idotea emarginata, the microplastic particles did not enter the digestive gland, which is the principle organ in crustaceans where digestion and resorption of nutrients takes place," states the biologist from AWI's North Sea Office.

In a long-term experiment the scientists could also show that isopods did not display any long-term effects even after feeding on microplastic enriched food for six to seven weeks. 

Fitness parameters such as survival rate and growth did not differ between animals that were fed with and without microplastics, respectively. In an earlier study, however, AWI biologist Prof. Dr. Angela Köhler demonstrated that mussels show inflammatory reactions if they take up and absorb high concentrations of microplastic in an experiment. This clearly shows that different animal species react differently to microplastics. "In contrast to filter feeding mussels, isopods of the genus Idotea probably take up more frequently indigestible particles with their food in their natural habitat and may, thus, have adapted accordingly," elucidates Gutow.

But the biologists are not only interested in the feeding type: "We want to study systematically how the life style, habitat, physiology and anatomy of different marine organisms influence the uptake and utilisation of microplastic particles in order to come up with a risk matrix for diverse types of organisms," says Lars Gutow. "Therefore, it will be necessary to also study the possible chemical (toxic) and biochemical effects in addition to the physical effects that we looked at," he outlines future tasks.

Source: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research

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Dolly Varden are a species of char common in southeast Alaska. The fish shown is in spawning coloration.

Not all species may suffer from climate change. A new analysis shows that Dolly Varden, a species of char common in southeast Alaska, adjust their migrations so they can keep feasting on a key food source -- salmon eggs -- even as shifts in climate altered the timing of salmon spawning.

The resiliency of species to climate change may depend on how well they adapt to climate-driven changes in their food and habitat, such as altered growth of plants they feed on. A mismatch in timing between predators and the availability of prey could cause some species to lose access to food. But others such as Dolly Varden that successfully adjust to shifts in climate and prey offer a climate change story with a happy ending, according to the study published in Freshwater Biology.

Ignoring environmental cues may help this predator

The Dolly Varden's secret appears to be that instead of taking its migration cues from environmental variables such as water temperature or streamflow, the species cues directly off the presence of salmon the Dolly Varden depend on for food, the study found.

"Despite warming temperatures and shifting salmon migrations, Dolly Varden do a great job of following their food," said lead author Chris Sergeant of the National Park Service's Inventory and Monitoring Program in southeast Alaska. "Species that can handle a high degree of variability are the ones that should be most resilient to further changes associated with climate."

Dolly Varden get most of their energy over the course of each year by gorging themselves on salmon eggs, which are abundant in summer and rich in energy thanks to the same fatty acids that make fish healthy for humans. Eggs from any single species of salmon may be available during a narrow spawning window of two to six weeks. The Dolly Varden must follow salmon migrations closely to take full advantage of this annual salmon egg bonanza.

Sticking with salmon to find food

But salmon migrations are shifting as the climate warms. Previous research by the University of Alaska and NOAA Fisheries' Alaska Fisheries Science Center in southeast Alaska's Auke Creek has shown that pink and coho salmon now migrate to their spawning grounds 10 to 17 days earlier while sockeye salmon migrate eight days earlier.

Instead of falling out of synch with salmon, though, seagoing Dolly Varden in Auke Creek have accurately adjusted their annual migrations from the ocean back to freshwater to stick with the salmon. The adjustment has maintained their access to egg meals, according to the new research that includes coauthors from the University of Wyoming and NOAA Fisheries' Northwest Fisheries Science Center.

Researchers rely on long record of fish migration data

The research depended on a wealth of fish data from a weir on Auke Creek maintained primarily since 1980 by NOAA Fisheries' Alaska Fisheries Science Center Auke Bay Labs, supported by collaborations with the University of Alaska Fairbanks and Alaska Department of Fish and Game. From 1997 to 2006 crews counted and measured Dolly Varden migrating from the ocean, past the weir and into Auke Creek, providing an unusual long-term picture of fish migration times.

"We're really indebted to the people who kept that record going for so long," said Eric Ward of the Northwest Fisheries Science Center. "It turns out to be very valuable in understanding how species are responding to the changing climate."

Researchers in the new study used the weir data to examine the relationship between migrations of salmon and Dolly Varden from year to year. They found the timing of Dolly Varden migration more closely related to the presence and timing of the salmon than on environmental variables such as temperature and precipitation that are often seen as driving animal migrations.

In short, the Dolly Varden are shifting their migration to follow their food instead of following temperatures or other environmental cues that, as the climate changes, might otherwise lead them to migrate at a different time than the salmon that provide their most important food.

The researchers cautioned that it's unclear whether other salmon predators could adjust their timing to follow salmon as effectively as Dolly Varden do, apparently by watching salmon passing by or detecting salmon eggs through smell. But the adaptability of Dolly Varden suggests that at least some species may be more resilient to climate-induced changes in migration timing than ecologists might assume.

Source: NOAA Fisheries West Coast Region

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Arctic conditions may become critical for polar bears by end of 21st century

This is a photo of an Arctic polar bear. Shifts in the timing and duration of ice cover, especially the possible lengthening of ice-free periods, may impact polar bears under projected warming before the end of the 21st century, according to a study published Nov. 26, 2014 in the open-access journal PLOS ONE by Stephen Hamilton from University of Alberta and colleagues. Credit: Andrew Derocher; CC-BY

Shifts in the timing and duration of ice cover, especially the possible lengthening of ice-free periods, may impact polar bears under projected warming before the end of the 21st century, according to a study published November 26, 2014 in the open-access journal PLOS ONE by Stephen Hamilton from University of Alberta and colleagues.

Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems, and polar bears are vulnerable to these changes in sea ice conditions. The authors of this study used sea ice projections for the Canadian Arctic Archipelago from 2006-2100 and metrics developed from polar bear energetics modeling to gain insight into the conservation challenges for polar bears facing habitat loss.

Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100. "We predict that nearly one-tenth of the world's polar bear habitat, as much as one-quarter of their global population, may undergo significant habitat loss under business-as-usual climate projections," said Stephen Hamilton.

Source: PLOS

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Climate change projected to drive species northward

Coho salmon are among the species anticipated to shift northward with climate change. Credit: NOAA Fisheries

Anticipated changes in climate will push West Coast marine species from sharks to salmon northward an average of 30 kilometers per decade, shaking up fish communities and shifting fishing grounds, according to a new study published in Progress in Oceanography.

The study suggests that shifting species will likely move into the habitats of other marine life to the north, especially in the Gulf of Alaska and Bering Sea. Some will simultaneously disappear from areas at the southern end of their ranges, especially off Oregon and California.

"As the climate warms, the species will follow the conditions they're adapted to," said Richard Brodeur, a NOAA Fisheries senior scientist at the Northwest Fisheries Science Center's Newport Research Station and coauthor of the study. "We're going to see more interactions between species and there will be winners and losers that we cannot foresee."

The study, led by William Cheung of the University of British Columbia, estimated changes in the distribution of 28 near-surface fish species commonly collected by research surveys in the northeast Pacific Ocean. The researchers used established global climate models to project how the distribution of the fish would shift by 2050 as greenhouse gases warm the atmosphere and, in turn, the ocean surface.

Brodeur cautioned that like any models, climate models carry uncertainty. While they provide a glimpse of the most likely changes in global climate, they may be less accurate when estimating more fine-scale, local changes.

"Nothing is certain," he said, "but we think we have a picture of the most likely changes."
Some species shifts are already being documented as West Coast waters are warming: predatory Humboldt squid from Central and South America have invaded the West Coast of North America in recent years, albacore have shifted to more northerly waters and eulachon have disappeared from warming waters at the southern end of their range.

"Thinking more broadly, this re-shuffling of marine species across the whole biological community may lead to declines in the beneficial functions of marine and coastal ecosystems," said Tom Okey, a Pew Fellow in Marine Conservation at the University of Victoria and a coauthor of the study. "These declines may occur much more rapidly and in more surprising ways than our expected changes in species alone."

The study anticipates warm-water species such as thresher sharks and chub mackerel becoming more prominent in the Gulf of Alaska and off British Columbia. Some predators such as sea lions and seabirds, which rear their young in fixed rookeries or colonies, may find the fish they usually prey on moving beyond predators' usual foraging ranges.

"If their prey moves farther north, they either have to travel farther and expend more energy to get to them, or find something else to eat," Brodeur said. "It's the same thing for fishermen. If it gets warmer, the fish they depend on are going to move up north and that means more travel time and more fuel will be needed to follow them, or else they may need to switch to different target species. It may not happen right away but we are likely to see that kind of a trend."

El Nino years, when tropical influences temporarily warm the eastern Pacific, offer a preview of what to expect as the climate warms.

Shifts in marine communities may be most pronounced in high-latitude regions such as the Gulf of Alaska and Bering Sea, which the study identifies as "hotspots" of change. Cold-water species such as salmon and capelin have narrower temperature preferences than warmer water species, making them more sensitive to ocean warming and likely to respond more quickly.

An intrusion of warm-water species into cooler areas could lead to significant changes in marine communities and ecosystems. The diversity of northern fish communities, now often dominated by a few very prolific species such as walleye pollock, may increase as southern species enter the region, leading to new food web and species interactions.

Source: NOAA Fisheries West Coast Region

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Managing reefs to benefit coastal communities

Fishing. Credit: Josh Cinner

Coral reefs provide a range of benefits, such as food, opportunities for income and education, but not everyone has the same access to them, according to a new study conducted by the ARC Centre of Excellence for Coral Reef Studies at James Cook University.

The researchers examined how people from 28 fishing communities in Madagascar, Kenya, Tanzania and Seychelles benefit from the marine environment.

For many years conservation in developing countries has been based on the assumption that improvements in ecosystem conditions, such as increasing coral reef fish biomass, will benefit the community as a whole.

But Dr Christina Hicks, a social scientist, says this is approach is too simplistic.

"Increased supply tends to benefit the elite, not the community as a whole," Dr Hicks says.

"We need to look at the social and economic access mechanisms that would enable a wider group of people to benefit from reefs and then develop policies based on that information," she says.

Study co-author Professor Josh Cinner from the Coral CoE says the focus on increasing the supply of benefits isn't enough.

"We need to pay more attention to how that benefit is distributed and how it is accessed by different people within a community," Professor Cinner says.

The researchers argue that policy makers need a more inclusive approach to managing coral reefs, which includes a focus on improving wellbeing.

"We tend to focus on economic growth because it is easy to measure, but this should be greatly expanded to include the way people can share in the benefits that flow from reefs," Dr Hicks says.

Source:  ARC Centre of Excellence in Coral Reef Studies.

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You can hear the coral reefs dying, experts say

A lionfish in an Indonesian reef. Credit: Image courtesy of University of Essex

You can hear the sound of former bustling coral reefs dying due to the impact of human activity, according to new research from the Universities of Essex and Exeter.

Coral reefs are amongst the noisiest environments on our planet and healthy reefs can be heard using underwater microphones from kilometres away.

However, scientists have found that coral reefs impacted by human activity, such as overfishing, are much quieter than protected reefs, which can have a big impact on the fish and invertebrates which rely on the reefs for survival.

Led by Dr Julius Piercy, from the University of Essex, the study, which also involved the University of Derby, involved taking acoustic recordings of coral reefs with different levels of protection around islands in the Philippines. The research found that the noise produced by the few remaining resident fish and crustaceans on unprotected reefs was only one third of the sound produced at bustling, healthy reef communities

This is particularly important to the larval stages of reef fish and invertebrates, which spend the first few days of their life away from reefs and use sound as an orientation cue to find their way back. With less sound being produced at impacted reefs, the distance over which larvae can detect habitat is ten times less, impacting on the replenishment of future generations needed to build up and maintain healthy population levels.

"In an environment where underwater noise plays such an important role in the population dynamics of coral reefs, it is alarming to find such a large effect of human impact on the natural acoustic environment," explained Dr Piercy. "This puts reef sound in the spotlight for the people who manage coral reef ecosystems on two counts. Firstly, that they might need to consider reef sound as an integral part of the design of marine protected area networks to ensure that there is sufficient recruitment of larvae within and between reserves and neighbouring reefs. Secondly, this study shows sound can be useful in monitoring the health of coral reefs."

With growing evidence demonstrating the direct impacts of human-made noise on aquatic life, these findings highlight additional indirect human impacts -- such as overfishing and landscape development -- on natural underwater sounds.

Dr Steve Simpson, from Biosciences at the University of Exeter, added: "Taking sound recordings is a cheap, fast and objective way to get a broad idea of whether a reef is in a good condition or not. While it cannot replace detailed visual surveys conducted by snorkelers or divers, it gives a good account of the cryptic and nocturnal species missed in visual census, and quickly provides a general picture of the state of coral reefs without requiring time-consuming surveys and extensive training."

The researchers also found that reef sounds can be detected further away than predicted, increasing previous estimates of the likely detection zone for recruiting larvae and increasing the potential importance of reef sound in attracting new fish and crustaceans to coral reefs.

The study highlights the need to further characterise reef soundscapes and identify acoustic cues that larvae tune into when seeking a suitable home. Dr Simpson said: "We still know very little about what sounds these animals are listening to and it is likely to be very different between species. Combined with recent findings that fish dislike the smell of impacted reefs (another homing cue used by the larvae), there is a real need to understand how human impacts can indirectly affect the success of future generations of reef organisms."

Source: University of Essex

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Recreational activity a major pollutant on Canadian coast of Pacific Ocean

This is University of Calgary associate professor in geography Stefania Bertazzon.
Credit: Robert Walker

From recreational boats and fishing vessels to commercial cruise ships and private marinas, a newly published study shows that oil discharges related to human maritime activity on the Canadian coast is posing a major threat to marine ecosystems in the Pacific Ocean.

The study -- published in the August edition of the journal Applied Geography, with University of Calgary associate professor in geography Stefania Bertazzon as lead author -- provides a geospatial analysis of oil discharges in the Canadian Pacific Ocean.

The findings show that a large portion of oil discharge within these waters stems from recreational activities, passenger traffic and fisheries. According to this scientific analysis -- conducted on oil spills observed by the National Aerial Surveillance Program with the use of remote sensing devices -- these sources are polluting the ocean along the British Columbia coast more than oil tankers and commercial cargo ships.

"Cargo ships and oil tankers are much more regulated with portside inspections and they have to meet certain standards," explains Bertazzon. "They're very aware of this surveillance and this is probably why our analysis suggests that they are responsible for a smaller portion of detected oil discharges. They have to be more careful."

Bertazzon adds: "We're not saying that cargo ships and oil tankers are not polluting. What we are saying is that they are not the only source of pollution in the Canadian Pacific Ocean."
Bertazzon and her co-authors explain that fuel docks for recreational and fishing vessels can be problematic. "We know that there's a lot of oil discharge in these fuel docks, which is largely uncontrolled," she says.

"One thing that happens in these marinas is there's a lot of old boats which have been sitting there for years slowly leaking into the ocean. These are not huge spills. It's a relatively small discharge. But there's a lot of these derelict vessels and together they make for a large source of pollution."

While there's no denying the impact of large-scale oil industry disasters such as the Gulf of Mexico spill in 2010, Bertazzon argues that the oil discharges related to maritime activities are even more devastating to marine ecosystems in the long run.
"There is scientific evidence to show that these day to day activities have a larger impact on the wild life and the marine ecosystem than those accidents that are huge, but limited in space and time," says Bertazzon. "What we're talking about happens every day, all along the coast. The impact is longer term and over a larger spatial extent."

Source:  University of Calgary

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