Natural variation: Warm North Atlantic Ocean promotes extreme winters in US and Europe

The extreme cold weather observed across Europe and the east coast of the US in recent winters could be partly down to natural, long-term variations in sea surface temperatures, according to a new study published today.Researchers from the University of California Irvine have shown that a phenomenon known as the Atlantic Multidecadal Oscillation (AMO) — a natural pattern of variation in North Atlantic sea surface temperatures that switches between a positive and negative phase every 60-70 years — can affect an atmospheric circulation pattern, known as the North Atlantic Oscillation (NAO), that influences the temperature and precipitation over the Northern Hemisphere in winter.When the AMO is in its positive phase and the sea surface temperatures are warmer, the study has shown that the main effect in winter is to promote the negative phase of the NAO which leads to “blocking” episodes over the North Atlantic sector, allowing cold weather systems to exist over the eastern US and Europe.The results have been published today, Wednesday 2 April, in IOP Publishing’s journal Environmental Research Letters.To arrive at their results, the researchers combined observations from the past century with climate simulations of the atmospheric response to the AMO.According to their observations, sea surface temperatures in the Atlantic can be up to 1.5 C warmer in the Gulf Stream region during the positive phase of the AMO compared to the negative, colder phase. The climate simulations suggest that these specific anomalies in sea surface temperatures can play a predominant role in promoting the change in the NAO.Lead authors of the study Yannick Peings and Gudrun Magnusdottir said: “Our results indicate that the main effect of the positive AMO in winter is to promote the occurrence of the negative phase of the NAO. A negative NAO in winter usually goes hand-in-hand with cold weather in the eastern US and north-western Europe.”The observations also suggest that it takes around 10-15 years before the positive phase of AMO has any significant effect on the NAO. The reason for this lag is unknown; however, an explanation might be that AMO phases take time to develop fully.As the AMO has been in a positive phase since the early 1990s, it may have contributed to the extreme winters that both the US and Europe have experienced in recent years.The researchers warn, however, that the future evolution of the AMO remains uncertain, with many factors potentially affecting how it interacts with atmospheric circulation patterns, such as Arctic sea ice loss, changes in solar radiation, volcanic eruptions and concentrations of greenhouse gases in the atmosphere.The AMO also shows strong variability from one year to the next in addition to the changes seen every 60 – 70 years, which makes it difficult to attribute specific extreme winters to the AMO’s effects.Responding to the extreme weather that gripped the eastern coast of the US this winter, Yannick Peings continued: “Unlike the 2012/2013 winter, this winter had rather low values of the AMO index and the pattern of sea surface temperature anomalies was not consistent with the typical positive AMO pattern. Moreover, the NAO was mostly positive with a relatively mild winter over Europe.””Therefore it is unlikely that the positive AMO played a defining role on the east coast of the US, although further work is necessary to answer this question. Such an event is consistent with the large internal variability of the atmosphere, and other external forcings may have played a role.”Our future studies will look to compare the role of the AMO compared to Arctic sea ice anomalies, which have also been shown to affect atmospheric circulation patterns and promote colder, more extreme winters.”Story Source:The above story is based on materials provided by Institute of Physics. Note: Materials may be edited for content and length.

Read more

Biologists use sound to identify breeding grounds of endangered whales

Remote acoustic monitoring among endangered whales is the subject of a major article by two doctoral students in The College of Arts and Sciences.Leanna Matthews and Jessica McCordic, members of the Parks Lab in the Department of Biology, have co-authored “Remote Acoustic Monitoring of North Atlantic Right Whales Reveals Seasonal and Diel Variations in Acoustic Behavior.” The article appears in the current issue of PLOS ONE, an inclusive, peer-reviewed, open-access resource from the Public Library of Science in San Francisco.Susan Parks, assistant professor of biology for whom the lab is named, says the article confirms what many conservationists fear — that Roseway Basin, a heavily traveled shipping lane, off the coast of Nova Scotia, is a vital habitat area for the endangered North Atlantic right whale.”Remote acoustic monitoring is an important tool for understanding patterns in animal communication, and studies on the seasonality of context-specific acoustic signals allow inferences to be made about the behavior and habitat use of certain species,” says Parks, an expert in behavioral ecology, acoustic communication and marine science. “Our results support the hypothesis that the North Atlantic right whale’s breeding season occurs mostly from August to November and that this basin is a widely used habitat area.”More than 30 percent of all right whales use Roseway Basin, part of a larger geological formation called the Scotian Shelf, throughout the year. With only 400-500 in existence, these whales, says Parks, must congregate in the basin to feed and find mates.Already, the U.S. and Canadian governments have taken steps to redirect shipping traffic, in response to several fatal collisions with right whales.Matthews, whose research includes animal behavior and physiology, says the object of the article is to determine how and when Roseway Basin is used for male breeding activities.”Part of the answer lies in a loud ‘gunshot’ sound, made by the male whale,” says Matthews, the article’s lead author. “We’re not exactly sure what the gunshot is, but we think it may be a male-to-male antagonistic signal or an advertisement to females. … During a two-year period, we used non-invasive acoustic monitoring to analyze gunshots at two locations on the Scotian Shelf. The resultant data has provided tremendous insights into the whales’ feeding and mating habits.”Matthews and her team found that gunshot sound production occurred mainly in the autumn and, more often than not, at night. Researchers say this kind of information is essential to not only the individual fitness of each whale, but also the survival of the species, in general.McCordic, whose research spans animal behavior and communication, says the observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season.”Our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior, including possible mating activities,” she says, acknowledging David Mellinger, associate professor of marine bioacoustics at Oregon State University, who collected and provided access to the recordings used in the study. “It also provides a better understanding of right whale behavior and what needs to be done with future conservation efforts.”Parks, who assisted with the article, is proud of her students’ accomplishments.”Right whales are increasingly rare, and Leanna’s and Jessica’s research helps us understand how to better protect them,” she says. “By identifying potential breeding areas, we might be able to save this critically endangered species.”Story Source:The above story is based on materials provided by Syracuse University. …

Read more

‘RoboClam’ replicates a clam’s ability to burrow while using little energy

The Atlantic razor clam uses very little energy to burrow into undersea soil at high speed. Now a detailed insight into how the animal digs has led to the development of a robotic clam that can perform the same trick.The device, known as “RoboClam,” could be used to dig itself into the ground to bury anchors or destroy underwater mines, according to its developer, Amos Winter, the Robert N. Noyce Career Development Assistant Professor of Mechanical Engineering at MIT.Despite its rigid shell, the Atlantic razor clam (Ensis directus) can move through soil at a speed of 1 centimeter per second. What’s more, the animal is able to dig up to 0.5 kilometers using only the amount of energy contained in a AA battery. “The clam’s trick is to move its shells in such a way as to liquefy the soil around its body, reducing the drag acting upon it,” Winter says. “This means it requires much less force to pull its shell into the soil than it would when moving through static soil.”To develop a robot that can perform the same trick, Winter and his co-developer, Anette Hosoi, professor of mechanical engineering and applied mathematics at MIT, needed to understand how the clam’s movement causes the soil to liquefy, or turn into quicksand, around its shell. Now, in a paper to be published in the journal Bioinspiration and Biomimetics, the researchers reveal for the first time the mechanics behind this process, and describe how their robot is able to mimic this action.Mechanics of quicksandWhen the razor clam begins to dig, it first retracts its shell, releasing the stress between its body and the soil around it. This causes the soil to begin collapsing, creating a localized landslide around the animal. As the clam continues to contract, reducing its own volume, it sucks water into this region of failing soil. The water and sand particles mix, creating a fluidized substrate — quicksand.But the timing is crucial. …

Read more

Eel expedition 2014 has arrived in The Sargasso Sea

The research vessel Dana is currently in the Sargasso Sea on an intensive research expedition to the European eel’s spawning grounds subsequently following the eel larvae’s drift back to Europe. The Sargasso Sea is a large oceanic area between Bermuda and the West Indies. There are 19 species of eel in the world. Two of them spawn in the Sargasso Sea: The American and The European Eel.In the past 30 years there has been a dramatic decline in the European eel population. Today, the number of young eel returning to the coasts of Europe is just 2-10 per cent of the quantities seen in the 1970s. In 2008, the dramatic decline in eel numbers led the International Union for Conservation of Nature (IUCN) to add the eel to its list of critically endangered species.A characteristic feature of the European eel is that spawning takes place far from the juvenile nursery grounds in Europe, requiring the eel larvae to ride the ocean currents for a 6,000 kilometre return journey across the Atlantic. The expedition will investigate whether climate-related changes in the eel’s spawning grounds or the ocean currents transporting the eel larvae to Europe are responsible for the eel’s sharp decline. The expedition will also gather information on the food preferences of the newly hatched eel — the understanding of eel larval feeding is a prerequisite for successful rearing of larvae and the farming of eel. Farmed eel can be used for re-stocking and using these for consumption would lower the fishing pressure on the population.The expedition brings together almost 40 experts from a wide range of research areas at both Danish and international universities and institutions (including French, German,Swedish and American participants). The expedition, which is headed by Senior Researcher Peter Munk from DTU Aqua, is funded by the Danish Centre for Marine Research and the Carlsberg Foundation. …

Read more

Whales bearing young and humans drilling for oil in same African waters

Scientists with the Wildlife Conservation Society, Oregon State University, Stanford University, Columbia University, and the American Museum of Natural History have found that humpback whales swimming off the coast of western Africa encounter more than warm waters for mating and bearing young; new studies show that the whales share these waters with offshore oil rigs, major shipping routes, and potentially harmful toxicants.With the aid of satellite tags affixed to more than a dozen whales, the researchers have quantified the amount of overlap between hydrocarbon exploration and extraction, environmental toxicants, shipping lanes, and humpback whales occurring in their nearshore breeding areas. The scientists also identified additional parts of the whales’ breeding range and migratory routes to sub-Antarctic feeding grounds.The study appears in the latest edition of the journal Conservation Biology. The authors are: Howard Rosenbaum of the Wildlife Conservation Society and the American Museum of Natural History; Sara Maxwell of Stanford University; Francine Kershaw of Columbia University; and Bruce Mate of Oregon State University.”Throughout numerous coastal and offshore areas, important whale habitats and migration routes are increasingly overlapping with industrial development, a scenario we have quantified for the first time in the eastern South Atlantic,” said Dr. Howard Rosenbaum, Director of WCS’s Ocean Giants Program. “Studies such as this one are crucial for identifying important habitats for humpback whales and how to best protect these populations from potential impacts associated with hydrocarbon exploration and production, shipping, and other forms of coastal and offshore activities.”Rosenbaum added: “From understanding which habitats are most important to tracking their migrations, our work provides great insights into the current issues confronting these whales and how to best engage ocean industries to better protect and ensure the recovery of these leviathans.”Growing to approximately 50 feet in length, humpback whales are characterized by their long pectoral fins, acrobatic behavior, and haunting songs. Like other great whales, the humpback whale was hunted for centuries by commercial whaling fleets, with experts estimating a reduction of possibly 90 percent in its global population size. The International Whaling Commission has protected humpback whales globally from commercial whaling since 1968.While migration patterns of humpbacks have been the subject of extensive study in other ocean basins and regions, the migratory behaviors of humpbacks along the western African coast in the eastern South Atlantic are poorly described. To better understand the movements of humpback whales in the Gulf of Guinea, the researchers deployed satellite tags on 15 individual animals off the coast of Gabon between August and September of 2002.”This study demonstrates clearly that all of the countries on the west coast of Africa need to work together on a range-wide humpback whale conservation strategy and consider the possibility of creating a whale sanctuary,” said Professor Lee White, CBE, director of Gabon’s National Parks Agency. “Gabon supports the concept of a South Atlantic Whale Sanctuary and will continue to work with other nations in the region to this end.”Dr. Bruce Mate, who pioneered the satellite-monitored radio tagging of large whales, said: “This technology allows the science and conservation communities to discover detailed seasonal migration routes, timing and destinations, so we can characterize these important habitats and reduce potential impacts of human activities, even in the harshest possible marine environments.”The major goal of the study was to elucidate the unknown migratory movement of whales from breeding areas off western Africa to areas where the whales likely feed in Antarctic or sub-Antarctic waters. …

Read more

Local foods offer tangible economic benefits in some regions

Despite their typically small size and sparse distribution, farms that sell their products locally may boost economic growth in their communities in some regions of the U.S., according to a team of economists.”There has been a lot of hope, but little evidence, that local food systems can be an engine of economic growth in communities,” said Stephan Goetz, professor of agricultural and regional economics in Penn State’s College of Agricultural Sciences and director of the Northeast Regional Center for Rural Development. “Our findings show that, at least in certain regions of the country, community-focused agriculture has had a measurable effect on economic growth.”The team’s findings, which appear in the February 2014 issue of Economic Development Quarterly, shed new light on the role that local food sales play in economies, and may help inform policymakers about supporting community-focused agriculture programs. The researchers defined community-focused agriculture as farm enterprises that sell products directly to consumers or that generate farm income from agritourism activities or both. Agritourism offers harvest festivals, pick-your-own activities and other recreational opportunities to attract visitors to farms. According to the 2007 U.S. Census of Agriculture — the most recently available data at the time of this study — only 6.2 percent of all farms engage in direct sales, and even fewer engage in agritourism activities. Goetz and his colleagues measured the impact of community-focused agriculture on local economic growth by examining its impact on agricultural sales overall.”Rather than look at the direct effect of community-focused agriculture on economic growth, we looked at the effect of these operations on total agricultural sales, and then at how total agricultural sales affected economic growth,” said Goetz. The study is the first to measure the impacts of local food sales, and agricultural sales more broadly, in this way.Using county-level data from the 2002 and 2007 U.S. Census of Agriculture, the team analyzed the link between direct farm sales — sales made directly from farmer to consumer — and total farm sales. When they examined the data on a national basis, they found a positive but not statistically significant relationship between the two.Goetz said that a different picture emerged when they looked at the data by region, as defined by the U.S. …

Read more

Global ocean currents explain why Northern Hemisphere is the soggier one

Oct. 20, 2013 — A quick glance at a world precipitation map shows that most tropical rain falls in the Northern Hemisphere. The Palmyra Atoll, at 6 degrees north, gets 175 inches of rain a year, while an equal distance on the opposite side of the equator gets only 45 inches.Scientists long believed that this was a quirk of Earth’s geometry — that the ocean basins tilting diagonally while the planet spins pushed tropical rain bands north of the equator. But a new University of Washington study shows that the pattern arises from ocean currents originating from the poles, thousands of miles away.The findings, published Oct. 20 in Nature Geoscience, explain a fundamental feature of the planet’s climate, and show that icy waters affect seasonal rains that are crucial for growing crops in such places as Africa’s Sahel region and southern India.In general, hotter places are wetter because hot air rises and moisture precipitates out.”It rains more in the Northern Hemisphere because it’s warmer,” said corresponding author Dargan Frierson, a UW associate professor of atmospheric sciences. “The question is: What makes the Northern Hemisphere warmer? And we’ve found that it’s the ocean circulation.”Frierson and his co-authors first used detailed measurements from NASA’s Clouds and Earth’s Radiant Energy System, or CERES, satellites to show that sunlight actually provides more heat to the Southern Hemisphere — and so, by atmospheric radiation alone, the Southern Hemisphere should be the soggier one.After using other observations to calculate the ocean heat transport, the authors next used computer models to show the key role of the huge conveyor-belt current that sinks near Greenland, travels along the ocean bottom to Antarctica, and then rises and flows north along the surface. Eliminating this current flips the tropical rain bands to the south.The reason is that as the water moves north over many decades it gradually heats up, carrying some 400 trillion (that’s four with 14 zeroes after it) watts of power across the equator.For many years, slanting ocean basins have been the accepted reason for the asymmetry in tropical rainfall.”But at the same time, a lot of people didn’t really believe that explanation because it’s kind of a complicated argument. For such a major feature there’s usually a simpler explanation,” Frierson said.The ocean current they found to be responsible was made famous in the 2004 movie “The Day After Tomorrow,” in which the premise was that the overturning circulation shut down and New York froze over. While a sudden shutdown like in the movie won’t happen, a gradual slowing — which the recent United Nations report said was “very likely” by 2100 — could shift tropical rains south, the study suggests, as it probably has in the past.The slowdown of the currents is predicted because increasing rain and freshwater in the North Atlantic would make the water less dense and less prone to sinking.”This is really just another part of a big, growing body of evidence that’s come out in the last 10 or 15 years showing how important high latitudes are for other parts of the world,” Frierson said.Frierson’s earlier work shows how the changing temperature balance between hemispheres influences tropical rainfall. …

Read more

‘Stadium waves’ could explain lull in global warming

Oct. 10, 2013 — One of the most controversial issues emerging from the recent Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) is the failure of global climate models to predict a hiatus in warming of global surface temperatures since 1998. Several ideas have been put forward to explain this hiatus, including what the IPCC refers to as ‘unpredictable climate variability’ that is associated with large-scale circulation regimes in the atmosphere and ocean.The most familiar of these regimes is El Niño/La Niña, which are parts of an oscillation in the ocean-atmosphere system. On longer multi-decadal time scales, there is a network of atmospheric and oceanic circulation regimes, including the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation.A new paper published in the journal Climate Dynamics suggests that this ‘unpredictable climate variability’ behaves in a more predictable way than previously assumed. The paper’s authors, Marcia Wyatt and Judith Curry, point to the so-called ‘stadium-wave’ signal that propagates like the cheer at sporting events whereby sections of sports fans seated in a stadium stand and sit as a ‘wave’ propagates through the audience. In like manner, the ‘stadium wave’ climate signal propagates across the Northern Hemisphere through a network of ocean, ice, and atmospheric circulation regimes that self-organize into a collective tempo.The stadium wave hypothesis provides a plausible explanation for the hiatus in warming and helps explain why climate models did not predict this hiatus. Further, the new hypothesis suggests how long the hiatus might last.Building upon Wyatt’s Ph.D. thesis at the University of Colorado, Wyatt and Curry identified two key ingredients to the propagation and maintenance of this stadium wave signal: the Atlantic Multidecadal Oscillation (AMO) and sea ice extent in the Eurasian Arctic shelf seas. The AMO sets the signal’s tempo, while the sea ice bridges communication between ocean and atmosphere. The oscillatory nature of the signal can be thought of in terms of ‘braking,’ in which positive and negative feedbacks interact to support reversals of the circulation regimes. …

Read more

Newly discovered ocean plume could be major source of iron

Aug. 19, 2013 — Scientists have discovered a vast plume of iron and other micronutrients more than 1,000 km long billowing from hydrothermal vents in the South Atlantic Ocean. The finding, soon to be published in the journal Nature Geoscience, calls past estimates of iron abundances into question, and may challenge researchers’ assumptions about iron sources in the world’s seas.”This study and other studies like it are going to force the scientific community to reevaluate how much iron is really being contributed by hydrothermal vents and to increase those estimates, and that has implications for not only iron geochemistry but a number of other disciplines as well,” says Mak Saito, a WHOI associate scientist and lead author of the study.Saito and his team of collaborators — which includes WHOI researchers and a colleague affiliated with the University of Liverpool (U.K.) — didn’t set out to find iron plumes in the South Atlantic. They set sail aboard the R/V Knorr in 2007 as part of the Cobalt, Iron and Micro-organisms from the Upwelling zone to the Gyre (or CoFeMUG, pronounced “coffee mug”) expedition, which intended to map chemical composition and microbial life along the ship’s route between Brazil and Namibia. As the scientists traveled the route, they sampled the seawater at frequent intervals and multiple depths along the way, and then stored the samples for in-depth analysis back on land.Their route passed over the Mid-Atlantic Ridge, a band of mountains and valleys running along the Atlantic Ocean floor from the Arctic to the Antarctic where several of Earth’s major tectonic plates are slowly spreading apart. Hydrothermal vents, or fissures in Earth’s crust, are found along the ridge, but they haven’t been extensively studied because slow-spreading ridges are thought to be less active than fast-spreading ones. Past studies using helium, which is released from Earth’s mantle through hydrothermal vents and is routinely used as an indicator of vent activity, have found little coming from mid-Atlantic vents, and researchers have assumed that means the vents spew little iron as well.So Saito and his colleagues were surprised by what their samples revealed when later studied in the lab. Once filtered and analyzed, some of the seawater showed unexpectedly high levels of iron and manganese. When Abigail Noble, then a WHOI graduate student, and Saito plotted the sites where the iron-rich samples were taken, they realized the samples formed a distinct plume — a cloud of nutrients ranging in depth from 1,500 to 3,500 meters that spanned more than 1,000 km of the South Atlantic Ocean.”We had never seen anything like it,” Saito says. “We were sort of shocked — there’s this huge bull’s-eye right in the middle of the South Atlantic Ocean. …

Read more

Oldest European fort in the inland U.S. discovered in Appalachians

July 23, 2013 — The remains of the earliest European fort in the interior of what is now the United States have been discovered by a team of archaeologists, providing new insight into the start of the U.S. colonial era and the all-too-human reasons spoiling Spanish dreams of gold and glory.Spanish Captain Juan Pardo and his men built Fort San Juan in the foothills of the Appalachian Mountains in 1567, nearly 20 years before Sir Walter Raleigh’s “lost colony” at Roanoke and 40 years before the Jamestown settlement established England’s presence in the region.”Fort San Juan and six others that together stretched from coastal South Carolina into eastern Tennessee were occupied for less than 18 months before the Native Americans destroyed them, killing all but one of the Spanish soldiers who manned the garrisons,” said University of Michigan archaeologist Robin Beck.Beck, an assistant professor in the U-M Department of Anthropology and assistant curator at the U-M Museum of Anthropology, is working with archaeologists Christopher Rodning of Tulane University and David Moore of Warren Wilson College to excavate the site near the city of Morganton in western North Carolina, nearly 300 miles from the Atlantic Coast.The Berry site, named in honor of the stewardship of landowners James and the late Pat Berry, is located along a tributary of the Catawba River and was the location of the Native American town of Joara, part of the mound-building Mississippian culture that flourished in the southeastern U.S. between 800 and about 1500 CE.In 2004, with support from the National Geographic Society and the National Science Foundation, Beck and his colleagues began excavating several of the houses occupied by Spanish soldiers at Joara, where Pardo built Fort San Juan. Pardo named this small colony of Spanish houses Cuenca, after his own hometown in Spain. Yet the remains of the fort itself eluded discovery until last month.”We have known for more than a decade where the Spanish soldiers were living,” Rodning said. “This summer we were trying to learn more about the Mississippian mound at Berry, one that was built by the people of Joara, and instead we discovered part of the fort. For all of us, it was an incredible moment.”Using a combination of large-scale excavations and geophysical techniques like magnetometry, which provides x-ray-like images of what lies below the surface, the archaeologists have now been able to identify sections of the fort’s defensive moat or ditch, a likely corner bastion and a graveled surface that formed an entryway to the garrison.Excavations in the moat conducted in late June reveal it to have been a large V-shaped feature measuring 5.5 feet deep and 15 feet across. Spanish artifacts recovered this summer include iron nails and tacks, Spanish majolica pottery, and an iron clothing hook of the sort used for fastening doublets and attaching sword scabbards to belts.Fort San Juan was the first and largest of the garrisons that Pardo founded as part of an ambitious effort to colonize the American South. Pedro Menéndez de Avilés, who had established the Spanish colonies of St. Augustine and Santa Elena in 1565 and 1566, respectively, spearheaded this effort. …

Read more

Declining sea ice strands baby harp seals

July 22, 2013 — Young harp seals off the eastern coast of Canada are at much higher risk of getting stranded than adult seals because of shrinking sea ice cover caused by recent warming in the North Atlantic, according to a Duke University study.”Stranding rates for the region’s adult seals have generally not gone up as sea ice cover has declined; it’s the young-of-the-year animals who are stranding (those less than one year old),” said David Johnston, a research scientist at Duke’s Nicholas School of the Environment.”And it’s not just the weakest pups — those with low genetic diversity and presumably lower ability to adapt to environmental changes — that are stranding,” he said. “It appears genetic fitness has little effect on this.”The study, published online this week in the peer-reviewed open-access journal PLoS One, is the first to gauge the relative roles that genetic, environmental and demographic factors such as age and gender may be playing in harp seal stranding rates along the U.S. and Canadian east coasts in recent years.Harp seals rely on stable winter sea ice as safe platforms to give birth and nurse their young until the pups can swim, hunt and fend off predators for themselves. In years of extremely light ice cover, entire year-classes may be disappearing from the population, Johnston said.The new study complements a Duke-led study published last year that found seasonal sea ice cover in all four harp seal breeding regions in the North Atlantic has declined by up to 6 percent a decade since 1979, when satellite records of ice conditions in the region began.To expand upon the earlier study, Johnston and four colleagues at the Duke University Marine Lab compared images of winter ice from 1992 to 2010 in a major whelping region off Canada’s east coast, the Gulf of St. Lawrence, with yearly reports of dead harp seal strandings along the U.S. northeast coast that were grouped by gender and estimated age of the seal.The analysis revealed a significant difference: In years when ice cover was reduced, stranding rates for younger seals rose sharply, even though stranding rates for adult seals remained relatively stable.The researchers also compared DNA samples from 106 harp seals that had been stranded ashore with those from seals that had accidentally been caught by fishing boats in the region during the same period.”We used measures of genetic diversity to determine if the dead seals that came ashore were less fit than the presumably healthy ones that had been caught by fishermen, but found no difference,” said Thomas Schultz, director of Duke’s Marine Conservation Molecular Facility. “The stranded animals appear to have come from a genetically diverse population, and we have no evidence to suggest that genetic fitness played a role in their deaths.”The analysis also showed that male seals stranded more frequently than females during the study period, and that this relationship was strongest during light ice years.”Our findings demonstrate that sea ice cover and demographic factors have a greater influence on harp seal stranding rates than genetic diversity,” said Brianne Soulen, who co-led the study while she was a master’s degree student in marine ecology at Duke.Kristina Cammen, a Duke Ph.D. student who also co-led the study, said the findings “provide more context for what we’re seeing in high-latitude species in general. The effects of climate change are acting on younger animals; it’s affecting them during the crucial first part of their life.”

Read more

Cloud brightening to cool seas can protect coral reefs: Targeted cooling could offer a 50-year ‘breathing space’ for coral protection

July 10, 2013 — The seeding of marine clouds to cool sea surface temperatures could protect threatened coral reefs from being bleached by warming oceans. Research, published in Atmospheric Science Letters, proposes that a targeted version of the geo-engineering technique could give coral a fifty year ‘breathing space’ to recover from acidification and warming.”Coral bleaching over the last few decades has been caused by rising sea temperatures and ocean acidification,” said Dr Alan Gadian, from Leeds University. “Our research focuses on how Marine Cloud Brightening (MCB) could quickly lower sea temperatures in targeted areas.”There is a strong association between warmer-than-normal sea conditions and cases of coral bleaching. Bleaching is most likely to occur when a 1˚C temperature rise over a prolonged period, typically a 12-week period.To brighten clouds unmanned vehicles are used to spray tiny seawater droplets, which rise into the cloud, thereby increasing their reflectivity and duration. In this way, more sunlight is bounced back into space, resulting in a cooling sea surface temperature.While MCB was originally envisaged to be a global counter measure against warming, in principle the technique could be more targeted. In 2012 Dr. Gadian wrote how the use of MCB in the Atlantic could tame hurricanes.The new modeling study focuses the impact of seeding marine stratocumulus clouds over the Caribbean, French Polynesia, and the Great Barrier Reef. The study shows how the projected increases in coral bleaching, caused by rising CO2 levels, were eliminated while sea surface temperature cooled to pre-warming levels.Mild and severe coral bleaching events were projected over a 20-year period for the three target regions. Without MCB the amount of coral bleaching was seen to be severe; however, simultaneous deployment of MCB eliminated the risk of extra bleaching.”We estimate that MCB would have an annual cost of $400 million, however political, social and ethical costs make a true figure difficult to estimate, said Gadian. “Whatever the final figure, it will be less expensive than the damage the destruction of coral would wreck on neighboring countries, the local food chain and global biodiversity.”Public and political skepticism of geo-engineering projects remains a hurdle to their development; however, as the least disruptive form of Solar Radiation Management, the authors believe small-scale use of MCB for conservation would be unlikely to generate public opposition.The authors propose field-testing of MCB on a scale of 100 square metres, which could demonstrate its use, without producing significant climate effects. …

Read more

‘Dead zone’ impacts Chesapeake Bay fishes

July 8, 2013 — A 10-year study of Chesapeake Bay fishes by researchers at the Virginia Institute of Marine Science provides the first quantitative evidence on a bay-wide scale that low-oxygen “dead zones” are impacting the distribution and abundance of “demersal” fishes — those that live and feed near the Bay bottom.The affected species — which include Atlantic croaker, white perch, spot, striped bass, and summer flounder — are a key part of the Chesapeake Bay ecosystem and support important commercial and recreational fisheries.The study, published in a recent issue of Marine Ecology Progress Series, was authored by Andre Buchheister, a Ph.D. student in William & Mary’s School of Marine Science at VIMS, along with VIMS colleagues Chris Bonzek, Jim Gartland, and Dr. Rob Latour.All four authors are involved in VIMS’ Chesapeake Bay Multi-Species Monitoring and Assessment Program (ChesMMAP), an ongoing effort to track and understand interactions between and among fishes and other marine life within the Bay ecosystem.Buchheister says “This is the first study to document that chronically low levels of dissolved oxygen in Chesapeake Bay can reduce the number and catch rates of demersal fish species on a large scale.” He notes that other studies have looked at the effects of low oxygen on fishes within the water column and on demersal fishes within individual Bay tributaries.Low-oxygen conditions — what scientists call “hypoxia” — form when excessive loads of nitrogen from fertilizers, sewage, and other sources feed algal blooms in coastal waters. When these algae die and sink, they provide a rich food source for bacteria, which in the act of decomposition take up dissolved oxygen from nearby waters.In Chesapeake Bay, low-oxygen conditions are most pronounced in mid-summer, and in the deep waters of the Bay’s middle reaches. “This appears to displace fish biomass toward the northern and southern edges of the bay’s mainstem channel,” says Buchheister.”The drastic decline we saw in species richness, species diversity, and catch rate under low-oxygen conditions is consistent with work from other systems,” he adds. “It suggests that demersal fishes begin to avoid an area when levels of dissolved oxygen drop below about 4 milligrams per liter, as they start to suffer physiological stress.”The fishes’ response at this value is interesting, says Buchheister, “because it occurs at levels greater than the 2 milligrams per liter that scientists formally use to define hypoxia.” Normal coastal waters contain from 7-8 milligrams of oxygen per liter.Previous research suggests that oxygen-poor waters can stress fish directly, through increased respiration and elevated metabolism, and also by affecting their prey.”Low levels of dissolved oxygen stress or kill the bottom-dwelling invertebrates that demersal fishes rely on for food,” says Buchheister. “Prolonged exposure of these invertebrates to hypoxic conditions in the mid-Bay represents a substantial reduction in the habitat available for foraging by demersal fishes baywide, and could reduce the quality of foraging habitat even after bottom waters become re-oxygenated.”The authors caution, however, that the limits on fish abundance and distribution brought on by low-oxygen conditions are to some degree balanced by the positive effects that nutrients have on production of mid-water and surface-dwelling fishes elsewhere in the Bay. The nutrient-rich waters that encourage dead-zone formation also fuel algal growth, thus turbocharging the base of a food web that ultimately supports fish and other predators.ChesMMAPThe team’s findings are based on an exhaustive study of the distribution and abundance of late juvenile and adult fishes caught and released in trawl nets during 48 sampling trips between 2002 and 2011, the largest quantitative assessment of the bay-wide demersal fish community ever conducted. The sampling took place at 3,640 ChesMMAP stations throughout the mainstem of Chesapeake Bay.ChesMMAP, currently funded by Wallop-Breaux funds from the Virginia Marine Resources Commission, was established in 2002 as part of the growing international recognition that a single-species approach to fisheries management does not fully account for the complex interactions within marine ecosystems.Latour, head of the Multispecies Research Group at VIMS, says “The traditional approach to fisheries management looks at a single species as if it were independent, unaffected by other processes and having no effect on other species. In ChesMMAP and our other multispecies research programs we analyze the interactions between species and their environment, including studies of predator-prey dynamics, seasonal changes in distribution, and water-quality parameters such as temperature, salinity, and DO [dissolved oxygen].”SalinityIndeed, the team’s research shows that salinity is the most important factor affecting the distribution of Bay fishes, whether they live near the bottom or towards the surface.”Salinity was the major environmental gradient structuring community composition, biodiversity, and catch rates in our 10-year dataset,” says Buchheister. …

Read more

After Great Dane success, cancer doc eyes brain tumors

June 27, 2013 — Two University of Colorado Cancer Center publications set stage for K9 cancer vaccine test with human glioblastoma.Michael Graner, PhD, is a CU Cancer Center investigator and associate professor of neurosurgery at the CU School of Medicine. So when his 12-year-old Great Dane got sick, he knew what to do.”We got Star from the Mid-Atlantic Great Dane Rescue,” Graner says. “She got her name because she was always smiling, like a movie star waiting for photos. She’d already been to so many shelters, we didn’t want to change her name again and so we kept it.”At 12, after many years with the Graners, Star had already reached about double the average lifespan for the breed. When she collapsed during a coughing fit, Graner discovered the cause: lung cancer, specifically advanced bronchoalveolar adenocarcinoma with metastasis to the lymph nodes. The prognosis was grim, with a median survival from diagnosis of only about 6-27 days. And Star was well past the age when she could’ve tolerated chemotherapy or radiation.”With that diagnosis, chemotherapy has only a 10-15 percent response rate and she was old — with her prognosis and the drug side effects let’s just say chemotherapy wasn’t viable. We didn’t want to make her any sicker,” Graner says.So he turned to his specialty, immunotherapy. The idea is to circumvent the immune system’s nasty habit of recognizing cancer as its own tissue instead of seeing it as an invading disease and attacking it. By using engineered vaccines to prime the immune system to recognize tumors, cancer immunologists are using the body’s own defenses to clear itself of the disease. …

Read more

Scientists discover thriving colonies of microbes in ocean ‘plastisphere’

June 27, 2013 — Scientists have discovered a diverse multitude of microbes colonizing and thriving on flecks of plastic that have polluted the oceans — a vast new human-made flotilla of microbial communities that they have dubbed the “plastisphere.”In a study recently published online in Environmental Science & Technology, the scientists say the plastisphere represents a novel ecological habitat in the ocean and raises a host of questions: How will it change environmental conditions for marine microbes, favoring some that compete with others? How will it change the overall ocean ecosystem and affect larger organisms? How will it change where microbes, including pathogens, will be transported in the ocean?The collaborative team of scientists — Erik Zettler from Sea Education Association (SEA), Tracy Mincer from Woods Hole Oceanographic Institution (WHOI), and Linda Amaral-Zettler from the Marine Biological Laboratory (MBL), all in Woods Hole, Mass. — analyzed marine plastic debris that was skimmed with fine-scale nets from the sea surface at several locations in the North Atlantic Ocean during SEA research cruises. Most were millimeter-sized fragments.”We’re not just interested in who’s there. We’re interested in their function, how they’re functioning in this ecosystem, how they’re altering this ecosystem, and what’s the ultimate fate of these particles in the ocean,” says Amaral-Zettler. “Are they sinking to the bottom of the ocean? Are they being ingested? If they’re being ingested, what impact does that have?”Using scanning electron microscopy and gene sequencing techniques, they found at least 1000 different types of bacterial cells on the plastic samples, including many individual species yet to be identified. They included plants, algae, and bacteria that manufacture their own food (autotrophs), animals and bacteria that feed on them (heterotrophs), predators that feed on these, and other organisms that establish synergistic relationships (symbionts). …

Read more

Detour ahead: Cities, farms reroute animals seeking cooler climes

June 19, 2013 — In spite of considerable human development, the southeastern United States region could provide some of the Western Hemisphere’s more heavily used thoroughfares for mammals, birds and amphibians on their way to cooler environments in a warming world, according to new research led by the University of Washington.The region is among half a dozen areas that could experience heavier traffic compared with the average species-movement across the Western Hemisphere in response to a warming climate. The estimate in southeastern states, for example, is up to 2.5 times the average amount of movement across North and South America.Other areas that could see pronounced animal movements are northeastern North America, including around the Great Lakes and north into Canada; southeastern Brazil, home to both the species-rich Atlantic Forest and major cities such as Sao Paulo with its 11 million residents; and the Amazon Basin. The basin, stretching across seven South American countries, could have the greatest animal movements, up to 17 times the average across the hemisphere. The high northern latitudes also show pronounced species movements, not because of animals currently found there but because of an expected influx of species.While previous studies mapped where animals need to move to find climates that suit them, this is the first broad-scale study to also consider how animals might travel when confronted with cities, large agricultural areas and other human related barriers, according to Joshua Lawler, UW associate professor of environmental and forestry sciences and lead author of a paper appearing June 19 online in Ecology Letters.The golden mouse, ornate chorus frog and southern cricket frog — three of the species that will likely be on the move in southeastern U.S. — were among the nearly 3,000 mammals, birds and amphibians the scientists included in their study, nearly half of all such animals in the Western Hemisphere.”We took into account that many animals aren’t just going to be able to head directly to areas with climates that suit them,” Lawler said. “Some animals, particularly small mammals and amphibians, are going to have to avoid highways, agricultural development and the like. We also took into consideration major natural barriers such as the Great Lakes in North America and the Amazon River in South America.”Identifying where large numbers of species will need to move can help guide land use and conservation planning. Many of the animals moving southward through central Argentina will be funneled by agriculture and development through the more intact parts of the Gran Chaco region and into the Sierras de Córdoba and the Andes mountains. Similarly, the southern Appalachian Mountains in the southeastern U.S. are projected to act as a conduit for species moving northward in response to climate change.”These findings highlight the importance of the natural corridors that exist in these places — corridors that likely warrant more concerted conservation efforts to help species move in response to climate change,” Lawler said.In other places barriers may need to be breached for animals to disperse successfully.”Southeastern Brazil, for instance, has lots of species that need to move but is a heavily converted landscape. …

Read more

Snail genetic tracks reveal ancient human migration: Mesolithic humans may have carried snail species from France to Ireland

June 19, 2013 — Some snails in Ireland and the Pyrenees are genetically almost identical, perhaps because they were carried across the Atlantic during an 8000-year-old human migration. The snail genetics tie in with studies of human genetics and the colonization of Ireland, according to the research published June 19 in the open access journal PLOS ONE by Angus Davison and colleagues from the University of Nottingham, UK.Share This:Despite being thousands of miles apart, one variety of banded wood snails from Ireland and southern France share similar shell patterns and mitochondrial genes that are rarely seen in other areas of Europe. Davison explains, “There is a very clear pattern, which is difficult to explain except by involving humans. If the snails naturally colonized Ireland, you would expect to find some of the same genetic type in other areas of Europe, especially Britain. We just don’t find them.”He adds, “There are records of Mesolithic or Stone Age humans eating snails in the Pyrenees, and perhaps even farming them. The highways of the past were rivers and the ocean — as the river that flanks the Pyrenees was an ancient trade route to the Atlantic, what we’re actually seeing might be the long lasting legacy of snails that hitched a ride, accidentally or perhaps as food, as humans travelled from the South of France to Ireland 8,000 years ago.”Share this story on Facebook, Twitter, and Google:Other social bookmarking and sharing tools:|Story Source: The above story is reprinted from materials provided by Public Library of Science. Note: Materials may be edited for content and length. For further information, please contact the source cited above. Journal Reference:Adele J. Grindon, Angus Davison. …

Read more

Snail trail reveals ancient human migration

June 20, 2013 — Geneticists from The University of Nottingham have used snails to uncover evidence of an ancient human migration from the Pyrenean region of France to Ireland.Dr Angus Davison, Reader in Evolutionary Genetics at the University, and PhD student Adele Grindon, found that snails in Ireland and the Pyrenees are genetically almost identical, despite being thousands of miles apart. And — as snails aren’t renowned for their speed — the simplest explanation is that snails hitched a ride with human migrants approximately 8,000 years ago.The research is published in journal PLOS ONE on 19 June.From France to IrelandDr Davison said: “There is a very clear pattern, which is difficult to explain except by involving humans. If the snails naturally colonised Ireland, you would expect to find some of the same genetic type in other areas of Europe, especially Britain. We just don’t find them.”There are records of Mesolithic or Stone Age humans eating snails in the Pyrenees, and perhaps even farming them. The highways of the past were rivers and the ocean — as the river that flanks the Pyrenees was an ancient trade route to the Atlantic, what we’re actually seeing might be the long lasting legacy of snails that hitched a ride, accidentally or perhaps as food, as humans travelled from the South of France to Ireland 8,000 years ago.”The results tie in with what we know from human genetics about the human colonisation of Ireland — the people may have come from somewhere in southern Europe.”The flora and fauna of IrelandDespite being close geographically, Ireland is home to many plants and animals which aren’t found in Britain.Dr Davison said: “You would think that anything that gets to Ireland would go through Britain, but it has been a longstanding mystery as to why Ireland is so different from Britain. For these snails, at least, the difference may be that they hitched a ride on a passing boat.”

Read more

Jet stream changes cause climatically exceptional Greenland Ice Sheet melt

June 17, 2013 — Research from the University of Sheffield has shown that unusual changes in atmospheric jet stream circulation caused the exceptional surface melt of the Greenland Ice Sheet (GrIS) in summer 2012.An international team led by Professor Edward Hanna from the University of Sheffield’s Department of Geography used a computer model simulation (called SnowModel) and satellite data to confirm a record surface melting of the GrIS for at least the last 50 years — when on 11 July 2012, more than 90 percent of the ice-sheet surface melted. This far exceeded the previous surface melt extent record of 52 percent in 2010.The team also analysed weather station data from on top of and around the GrIS, largely collected by the Danish Meteorological Institute but also by US programmes, which showed that several new high Greenland temperature records were set in summer 2012.The research, published today in the International Journal of Climatology, clearly demonstrates that the record surface melting of the GrIS was mainly caused by highly unusual atmospheric circulation and jet stream changes, which were also responsible for last summer’s unusually wet weather in England.The analysis shows that ocean temperatures and Arctic sea-ice cover were relatively unimportant factors in causing the extra Greenland melt.Professor Hanna said: “The GrIS is a highly sensitive indicator of regional and global climate change, and has been undergoing rapid warming and mass loss during the last 5-20 years. Much attention has been given to the NASA announcement of record surface melting of the GrIS in mid-July 2012. This event was unprecedented in the satellite record of observations dating back to the 1970s and probably unlikely to have occurred previously for well over a century.”Our research found that a ‘heat dome’ of warm southerly winds over the ice sheet led to widespread surface melting. These jet stream changes over Greenland do not seem to be well captured in the latest Intergovernmental Panel on Climate Change (IPCC) computer model predictions of climate change, and this may indicate a deficiency in these models. According to our current understanding, the unusual atmospheric circulation and consequent warm conditions of summer 2012 do not appear to be climatically representative of future ‘average’ summers predicted later this century.”Taken together, our present results strongly suggest that the main forcing of the extreme GrIS surface melt in July 2012 was atmospheric, linked with changes in the summer North Atlantic Oscillation (NAO), Greenland Blocking Index (GBI, a high pressure system centred over Greenland) and polar jet stream which favoured southerly warm air advection along the western coast.”The next five-10 years will reveal whether or not 2012 was a rare event resulting from the natural variability of the NAO or part of an emerging pattern of new extreme high melt years. Because such atmospheric, and resulting GrIS surface climate, changes are not well projected by the current generation of global climate models, it is currently very hard to predict future changes in Greenland climate. Yet it is crucial to understand such changes much better if we are to have any hope of reliably predicting future changes in GrIS mass balance, which is likely to be a dominant contributor to global sea-level change over the next 100-1000 years.”

Read more

Human activity echoes through Brazilian rainforest

May 30, 2013 — The disappearance of large, fruit-eating birds from tropical forests in Brazil has caused the region’s forest palms to produce smaller, less successful seeds over the past century, researchers say. The findings provide evidence that human activity can trigger fast-paced evolutionary changes in natural populations.

Mauro Galetti from the Universidade Estadual Paulista in São Paulo, Brazil, along with an international team of colleagues, used patches of rainforest that had been fragmented by coffee and sugar cane development during the 1800’s to set up their natural experiment. They collected more than 9,000 seeds from 22 different Euterpe edulis palm populations and used a combination of statistics, genetics and evolutionary models to determine that the absence of large, seed-dispersing birds in the area was the main reason for the observed decrease in the palm’s seed size.

The study appears in the 31 May issue of the journal Science.

“Unfortunately, the effect we document in our work is probably not an isolated case,” said Galetti. “The pervasive, fast-paced extirpation of large vertebrates in their natural habitats is very likely causing unprecedented changes in the evolutionary trajectories of many tropical species.”

In general, researchers estimate that human activity, such as deforestation, drives species to extinction about 100 times faster than natural evolutionary processes. However, very few studies have successfully documented such rapid evolutionary changes in ecosystems that have been modified by human activity.

Galetti and the other researchers found that palms produced significantly smaller seeds in patches of forest that had been fragmented by coffee and sugar cane plantations and were no longer capable of supporting large-gaped birds, or those whose beaks are more than 12 millimeters wide, such as toucans and large cotingas. In undisturbed patches of forest, on the other hand, large-gaped birds still make their homes and palms continue to produce large seeds, successfully dispersed by the birds, they say.

“Small seeds are more vulnerable to desiccation and cannot withstand projected climate change,” explained Galetti. But, small-gaped birds, such as thrushes, that populate the fragmented patches of forest are unable to swallow and disperse large seeds. As a result of this impaired dispersal, palm regeneration became less successful in the area, with less-vigorous seedlings germinating from smaller seeds.

The researchers considered the influence of a wide range of environmental factors, such as climate, soil fertility and forest cover, but none could account for the change in palm seed size over the years in the fragmented forests. They performed genetic analyses to determine that the shrinkage of seeds among forest palms in the region could have taken place within 100 years of an initial disturbance.

This timescale suggests that the conversion of tropical forests for agriculture, which began back in the 1800’s and displaced many large bird populations in the region, triggered a rapid evolution of forest palms that resulted in smaller, less successful seeds.

Long periods of drought and increasingly warmer climate (as predicted by climate model projections for South America) could be particularly harmful to tropical tree populations that depend on animals to disperse their seeds. About 80 percent of the entire Atlantic rainforest biome remains in small fragments, according to the researchers, and the successful restoration of these habitats critically depends on the preservation of mutualistic interactions between animals and plants.

“Habitat loss and species extinction is causing drastic changes in the composition and structure of ecosystems, because critical ecological interactions are being lost,” said Galetti. “This involves the loss of key ecosystem functions that can determine evolutionary changes much faster than we anticipated. Our work highlights the importance of identifying these key functions to quickly diagnose the functional collapse of ecosystems.”

The report by Galetti et al. was supported by the Fundação de Amparo do Estado de São Paulo, Conselho Nacional de Desenvolvimento Científico and Programa Iberoamericano de Ciencia y Tecnología para el Desarollo.

Read more

Utilizzando il sito, accetti l'utilizzo dei cookie da parte nostra. maggiori informazioni

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close