OREGON STATE UNIVERSITY

scientific research and advances

Study: Pacific Northwest shows warming trend over past century-plus

CORVALLIS, Ore. – The annual mean temperature in the Pacific Northwest has warmed by about 1.3 degrees Fahrenheit since the early 20th century – a gradual warming trend that has been accelerating over the past 3-4 decades and is attributed to anthropogenic, or human, causes.

The study is one of the first to isolate the role of greenhouse gases associated with regional warming, the authors say. It was published in a recent issue of the Journal of Climate, a publication of the American Meteorological Society.

“The amount of warming may not sound like a lot to the casual observer, but we already are starting to see some of the impacts and what is particularly significant is that the rate of warming is increasing,” said Philip Mote, director of the Oregon Climate Change Research Institute at Oregon State University and a co-author on the study.

“Just a 1.3-degree increase has lengthened the ‘freeze-free’ season by 2-3 weeks and is equivalent to moving the snowline 600 feet up the mountain,” Mote added. “At the rate the temperature is increasing, the next 1.3-degree bump will happen much more quickly.”

In their study, the researchers looked at temperatures and precipitation from 1901 to 2012 in the Northwest, which includes Washington, Oregon, Idaho, western Montana, and the northwestern tip of Wyoming. They examined four different factors to determine the influence of human activities, including greenhouse gases and aerosols; solar cycles; volcanic eruptions; and naturally occurring phenomena including El Niño events and the Pacific Decadal Oscillation.

Using what is called a “multilinear regression” approach, they were able to tease out the influences of the different factors. Volcanic activity, for example, led to cooler temperatures in 1961, 1982 and 1991. Likewise, El Niño events led to warming in numerous years.

“Natural variation can explain much of the change from year to year, but it cannot account for this long-term warming trend,” noted David Rupp, a research associate with the Oregon Climate Change Research Institute and co-author on the report. “Anthropogenic forcing was the most significant predictor of, and leading contributor to, the warming.”

Among the study’s findings:

  • The Northwest experienced relatively cool periods from 1910-25 and from 1945-60, and a warm period around 1940 and from the mid-1980s until the present.
  • The warmest 10-year period has been from 1998 to 2007, and very few years since 1980 have had below average annual mean temperatures.
  • The most apparent warming trend is in the coldest night of the year, which has warmed significantly in recent decades.
  • The only cooling trend the study documented was for spring temperatures the last three decades and is tied to climate variability and increasing precipitation during those spring months.

“The spring has been robustly wetter,” Mote said, “and that has brought some cooler temperatures for a couple of months. But it has been drier in the fall and winter, and the warming in fall and winter has been steepest since the 1970s.”

Lead author John Abatzoglou of the University of Idaho said that the study ties the warming trend to human activities.

“Climate is a bit like a symphony where different factors like El Niño, solar variability, volcanic eruptions and manmade greenhouse emissions all represent different instruments,” Abatzoglou said. “At regional scales like in the Northwest, years or decades can be dominated by natural climate variability, thereby muffling or compounding the tones of human-induced warming.

“Once you silence the influence of natural factors,” he said, “the signal of warming due to human causes is clear – and it is only getting louder.”

The researchers also explored but were unable to find any link between warming in the Northwest over the past century and solar variability.

A major concern, the authors say, is that the warming seems to be increasing.

“Climate is complex and you can get significant variations from year to year,” Mote said. “You have to step back and look at the big picture of what is happening over time. Clearly the Northwest, like much of the world, is experiencing a warming pattern that isn’t likely to change and, in fact, is accelerating.

“At this rate, the chance of the temperature only going up 1.3 degrees in the next century is close to zero.”

The study was funded by the U.S. Department of Agriculture and the National Oceanic and Atmospheric Administration.

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Phil Mote, 541-913-2274, philip.mote@coas.oregonstate.edu

David Rupp, 541-737-5222, David.Rupp@oregonstate.edu

John Abatzoglou, jabatzoglous@uidaho.edu, 208-885-6239

OSU researchers tagging whales off southern California

NEWPORT, Ore. – Oregon State University researchers are tagging blue and fin whales off the coast of southern California this summer to study their movements, some of which include preferred feeding grounds near areas of heavy ship traffic.

The project, which is being funded by the U.S. Navy, will build on a previous study by OSU researchers that documented the seasonal distribution of blue whales, including their appearance near established shipping lanes off Santa Barbara. That analysis was based on satellite tracking of 171 blue whales for up to 13 months during a 15-year stretch from 1993 to 2008.

It was published last month in the journal PLOS ONE. Since that publication, six major shipping companies voluntarily agreed to slow their ships near Santa Barbara to lessen the chance of striking endangered blue whales, and to reduce pollution.

“No one wants to see whales hit by ships, and it is clear from the analysis that there has been some historic overlap of blue whale feeding areas and shipping lanes,” said Bruce Mate, director of Oregon State University’s Marine Mammal Institute, which is conducting the tagging project. “The goal of the new Navy-funded project is to better understand the seasonal occurrence of blue and fin whales in southern California and determine if that overlap is still taking place for these protected species.”

An OSU team led by Ladd Irvine began tagging the whales last month and thus far has successfully deployed 21 tags. The researchers hope to attach 24 long-term satellite tracking tags – a dozen each for blue whales and fin whales – and another eight more sophisticated tags that will track the whales’ underwater feeding habits. They hope to attach four of these Advanced-Dive-Behavior tags on blue whales and four on fin whales.

OSU’s recently published 15-year analysis was the most comprehensive study of blue whales movements ever conducted. It tracked the movement of blue whales off the West Coast to identify important habitat areas and environmental correlates, and subsequently to understand the timing of their presence near major ports and shipping traffic.

“The main areas that attract blue whales are highly productive, strong upwelling zones that produce large amounts of krill – which is pretty much all that they eat,” said Irvine, who was lead author on the PLOS ONE study. “The whales have to maximize their food intake during the summer before they migrate south for the winter, typically starting in mid-October to mid-November. It appears that two of their main foraging areas are coincidentally crossed by shipping lanes.”

An estimated 2,500 of the world’s 10,000 blue whales spend time in the waters off the West Coast of the Americas and are known as the eastern North Pacific population. Blue whales can grow to the length of a basketball court, weigh as much as 25 large elephants combined, and their mouths could hold 100 people, though their diet is primarily krill – tiny shrimp-like creatures less than two inches in length.

At a distance, fin whales look a lot like blue whales. They are the second largest of the whales and reach 75 feet in length – the size of two buses. The tall, columnar blows of fin whales look much like that of blue whales. Fin whales have a taller, sickle-shaped dorsal fin, a lower right lip that is white, and feed on schooling fish as well as krill.

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Bruce Mate, 541-867-0202; bruce.mate@oregonstate.edu

Science study: Sunlight, not microbes, key to CO2 in Arctic

CORVALLIS, Ore. – The vast reservoir of carbon stored in Arctic permafrost is gradually being converted to carbon dioxide (CO2) after entering the freshwater system in a process thought to be controlled largely by microbial activity.

However, a new study – funded by the National Science Foundation and published this week in the journal Science – concludes that sunlight and not bacteria is the key to triggering the production of CO2 from material released by Arctic soils.

The finding is particularly important, scientists say, because climate change could affect when and how permafrost is thawed, which begins the process of converting the organic carbon into CO2.

“Arctic permafrost contains about half of all the organic carbon trapped in soil on the entire Earth – and equals an amount twice of that in the atmosphere,” said Byron Crump, an Oregon State University microbial ecologist and co-author on the Science study. “This represents a major change in thinking about how the carbon cycle works in the Arctic.”

Converting soil carbon to carbon dioxide is a two-step process, notes Rose Cory, an assistant professor of earth and environmental sciences at the University of Michigan, and lead author on the study. First, the permafrost soil has to thaw and then bacteria must turn the carbon into greenhouse gases – carbon dioxide or methane. While much of this conversion process takes place in the soil, a large amount of carbon is washed out of the soils and into rivers and lakes, she said.

“It turns out, that in Arctic rivers and lakes, sunlight is faster than bacteria at turning organic carbon into CO2,” Cory said. “This new understanding is really critical because if we want to get the right answer about how the warming Arctic may feedback to influence the rest of the world, we have to understand the controls on carbon cycling.

“In other words, if we only consider what the bacteria are doing, we’ll get the wrong answer about how much CO2 may eventually be released from Arctic soils,” Cory added.

The research team measured the speed at which both bacteria and sunlight converted dissolved organic carbon into carbon dioxide in all types of rivers and lakes in the Alaskan Arctic, from glacial-fed rivers draining the Brooks Range to tannin-stained lakes on the coastal plain. Measuring these processes is important, the scientists noted, because bacteria types and activities are variable and the amount of sunlight that reaches the carbon sources can differ by body of water.

In virtually all of the freshwater systems they measured, however, sunlight was always faster than bacteria at converting the organic carbon into CO2.

“This is because most of the fresh water in the Arctic is shallow, meaning sunlight can reach the bottom of any river – and most lakes – so that no dissolved organic carbon is kept in the dark,” said Crump, an associate professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. “Also, there is little shading of rivers and lakes in the Arctic because there are no trees.”

Another factor limiting the microbial contribution is that bacteria grow more slowly in these cold, nutrient-rich waters.

“Light, therefore, can have a tremendous effect on organic matter,” University of Michigan’s Cory pointed out.

The source of all of this organic carbon is primarily tundra plants – and it has been building up for hundreds of thousands of years, but doesn’t completely break down immediately because of the Arctic’s cold temperatures. Once the plant material gets deep enough into the soil, the degradation stops and it becomes preserved, much like peat.

“The level of thawing only gets to be a foot deep or so, even in the summer,” Crump said. “Right now, the thaw begins not long before the summer solstice. If the seasons begin to shift with climate change – and the thaw begins earlier, exposing the organic carbon from permafrost to more sunlight – it could potentially trigger the release of more CO2.”

The science community has not yet been able to accurately calculate how much organic carbon from the permafrost is being converted into CO2, and thus it will be difficult to monitor potential changes because of climate change, they acknowledge.

“We have to assume that as more material thaws and enters Arctic lakes and rivers, more will be converted to CO2,” Crump said. “The challenge is how to quantify that.”

Some of the data for the study was made available through the National Science Foundation’s Arctic Long-Term Ecological Research project, which has operated in the Arctic for nearly 30 years.

Other authors on the study are Collin Ward and George Kling of the University of Michigan.

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Byron Crump, 541-737-4369; bcrump@coas.oregonstate.edu;

Rose Cory, 734-615-3199, rmcory@umich.edu

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OSU research helps Chinese crested terns make comeback

CORVALLIS, Ore. – A collaborative project between researchers in Oregon and Asia last year helped establish a new breeding colony for one of the world’s most endangered seabirds – the Chinese crested tern – which then had a global population estimated at fewer than 50 birds.

This summer, at least 43 of the critically endangered birds arrived at the colony on the island of Tiedun Dao in Zhejiang Province, forming at least 20 breeding pairs. By early August, 13 young birds had fledged.

“It is a remarkable success story,” said Dan Roby, a professor of wildlife ecology at Oregon State University, who helped establish the new breeding colony. “The lessons that we learned in Oregon through luring Caspian terns to new breeding colonies away from the Columbia River translated quite well to the Chinese crested terns.”

Once thought to be extinct, there were no recorded sightings of Chinese crested terns from the 1930s until 2000, when a few birds were rediscovered on the Matsu Islands. Until last year, there were only two known breeding colonies for this species of tern – both in island archipelagos close to China’s southeast coast.

Both of these colonies have been susceptible to illegal egg collection for food, as well as to typhoons that can devastate seabird breeding colonies, Roby pointed out. The effort to establish a new colony was the first step toward creating a network of island sanctuaries where Chinese crested terns and other seabird species of conservation concern could raise their young, he added.

To establish a new colony, a project team including students and faculty from OSU’s Department of Fisheries and Wildlife worked with colleagues in China to clear part of Tiedun Dao of brush, then planted 300 tern decoys on the island and used solar-powered recorders to broadcast vocalizations of both Chinese crested terns and greater crested terns, which are more numerous and not endangered.

“When greater crested terns establish a breeding colony, sometimes it lures in Chinese crested terns as well,” Roby said. “We just didn’t expect it to happen so quickly.”

The China project was designed to recapture the success that Roby and the Army Corps of Engineers had in establishing new breeding colonies in Oregon for Caspian terns far away from the Columbia River, where they had been decimating juvenile salmon migrating downstream. They established new colonies in southeast Oregon and successfully lured thousands of birds to the new sites.

The technique of clearing vegetation, planting decoys and luring birds through playback of vocalizations was developed by Stephen Kress of the National Audubon Society.

Even though the new breeding colony for Chinese crested terns was successful, it wasn’t without peril, according to Simba Chan, senior conservation officer of BirdLife International’s Asia Division, who stayed on Tiedun Dao from early May to early August to monitor the colony. During that time, the endangered birds and their chicks endured attempted predation by peregrine falcons, attempted poaching by an egg collector, and three typhoons.

Chan and his colleagues collected a lot of data about the birds’ behavior that will help inform the management of the birds as well as the design of future colonies.

Chinese crested terns are highly efficient at finding and catching forage fish and adept at defending their nest sites during territorial disputes with their neighbors. Crested terns breed in very dense colonies with six to seven nesting pairs per square meter. The decline and near-extinction of Chinese crested terns in the 20th century was likely due to their restricted breeding range and widespread overharvest of seabird eggs.

“Having a new, productive breeding site away from the other two known colonies gives the species a far better chance to recover,” Roby said.

The project was supported by numerous international groups.

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Dan Roby, 541-737-1955; Daniel.roby@oregonstate.edu

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First tagging study of Antarctic minke whales shows unique feeding

NEWPORT, Ore. – Scientists for the first time have used tags to track the behavior of Antarctic minke whales and discovered that this smallest of the lunge-feeding whales utilizes the sea ice more than expected and feeds in ways unique from other species.

The study is also important from another standpoint: The researchers were able to acquire significant data on minke whales using non-lethal methods. Minkes have been the subject of lethal sampling by some countries under the label of “scientific whaling.”

Results of the study, which was funded by the National Science Foundation, are being published in the Journal of Experiment Biology.

“We know a lot about the feeding and diving behavior of larger whales, but not as much has been known about minke whales – especially in Antarctica,” said Ari Friedlaender, a principal investigator with the Marine Mammal Institute at Oregon State University and lead author on the study. “They are major krill predators and understanding how and where they feed is important.

“It gives us a better understanding of how changes in sea ice might affect these whales and the Antarctic ecosystem,” he added.

In their study, the researchers used suction cup tags equipped with multiple sensors to track the feeding performance of minke whales in Antarctica. They recorded 2,831 feeding events during 649 foraging dives from the tag records. They discovered that the small size of the minke whales provides them with better maneuverability, which enables them to navigate in and around the ice to locate krill.

Unlike larger whales, however, minke whales are limited by their comparatively small feeding apparatus. In other words, they cannot take in as much krill-filled water as their larger counterparts. Larger baleen whales feed by taking a small number of very large gulps – encompassing from 100 to 150 percent of their body mass.

Minke whales, in contrast, take high numbers of much smaller gulps – no more than 70 percent of their body mass, and often much less, according to Friedlander, an associate professor in the Department of Fisheries and Wildlife who works out of OSU’s Hatfield Marine Science Center in Newport, Ore.

“They compensate by making many more lunges per dive than other whales,” Friedlaender noted. “They are able to do this because their physiology keeps the energy cost of each lunge very low. We documented minke whales that made foraging dives beneath sea ice that included as many as 24 lunges for krill on each dive – the highest feeding rate for any lunge-feeding whale.”

The Antarctic minke whales occupy a unique niche in the ecosystem, the researchers pointed out. Penguins and seals also feed on krill, but the filter-feeding ability of minke whales allows them to consume greater quantities of the small crustaceans during their dives. The key, researchers say, is their ability to utilize dense patches of prey, which the minke whales can do because of their maneuverability.

The average dive of a minke whale was about 18 meters deep and lasted about a minute-and-a-half. However, the researchers documented dives as deep as 105 meters and lasting as long as seven minutes.

“These kinds of data are important to document because we just haven’t known much about minke whales in any region, but particularly in Antarctica,” Friedlaender pointed out. “The logistics of working in a remote environment, in and around the sea ice – and the difficulty of even approaching the whales - has made them a tough species to study.

“The recent advancement of multi-sensor tag technology helped make this possible.”

Other authors on the paper include Jeremy Goldbogen, Stanford University; Doug Nowacek, Andrew Read and David Johnston, Duke University; and Nick Gales, Australian Antarctic Division.

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Ari Friedlaender, 541-867-0202; ari.friedlaender@oregonstate.edu

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Few surfers are deterred by ocean bacteria that makes them sick

CORVALLIS, Ore. – Health warnings issued when beaches have high levels of bacteria do not keep many surfers out of the water, according to a new study by Oregon State University.

Nearly three in 10 surfers admit they knowingly surf during health advisories – nearly the same amount that chooses not to surf during periods of elevated bacteria. About 40 percent of surfers said they were unaware if they had ever surfed during an active health advisory.

The data can help public officials better warn surfers of potential health risks, said Anna Harding, co-author of the study and professor in OSU's College of Public Health and Human Sciences.

"Beach advisories for bacteria are not having their intended effect of dissuading surfers,” Harding said. “The lack of awareness about advisories – and willingness to take risks surfing in water that may be contaminated – suggests the need to educate surfers about behaviors that make them vulnerable to illness."

More than 500 surfers from the Pacific Northwest provided information for OSU's study and spanned a wide range of ages, incomes, surfing frequency and other demographics.

Of those surveyed by OSU, nearly 40 percent reported ear infections or discharge at some point during surfing; 30 percent, a sore throat or cough; 16 percent experienced diarrhea; 10 percent, fever; and 7 percent had vomited. Results were consistent across experience levels and were not lessened by showering after surfing.

Surfing during and after rain also led to higher rates of waterborne illnesses. Surfers are attracted to large waves that accompany a storm, but rain can send fecal bacteria from stormwater outfalls into the Pacific Ocean, as well as flush harmful microbes from animal feces present in streams and rivers onto beaches.

Surfers cannot avoid swallowing water – which can include harmful bacteria – during wipeouts, Harding said. They ingest 10 times more ocean water than swimmers, about 170 milliliters a day, or half a can of soda, she added.

Health advisories are posted online and on signs around the West Coast. But not every beach entrance has a warning sign, and many surfers do not notice them, said Dave Stone, co-author of the study and an environmental and molecular toxicology professor in OSU's College of Agricultural Sciences.

Beach sampling by states is intermittent, tends to lag behind current conditions and cannot cover all waters, Stone added.

"The best thing surfers can do is pay attention to the weather and where stormwater outfalls are located," said Stone, a toxicologist with OSU Extension. “They should also bookmark beach advisory websites with the latest information.”

"Surfers can go far in minimizing their exposure to microbes just by choosing when and where to surf," he added.

When an advisory is issued for a particular beach, water contact is discouraged and state websites advise beachgoers to avoid any activities during which they might swallow water, such as swimming, surfing, diving, and kayaking.

Using earplugs during surfing also leads to higher rates of ear infections, OSU researchers found. Generic earplugs tend to let water and bacteria inside the ear, Stone said, and then trap it inside the canal

OSU's study was funded by Oregon Sea Grant and is available online in the Journal of Water and Health.

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Anna Harding, 541-737-3830

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Scientists caution against exploitation of deep ocean

CORVALLIS, Ore. – The world’s oceans are vast and deep, yet rapidly advancing technology and the quest for extracting resources from previously unreachable depths is beginning to put the deep seas on the cusp of peril, an international team of scientists warned this week.

In an analysis in Biogeosciences, which is published by the European Geosciences Union, the researchers outline “services” or benefits provided by the deep ocean to society. Yet using these services, now and in the future, is likely to make a significant impact on that habitat and what it ultimately does for society, they point out in their analysis.

“The deep sea is the largest habitat on Earth, it is incredibly important to humans and it is facing a variety of stressors from increased human exploitation to impacts from climate change,” said Andrew Thurber, an Oregon State University marine scientist and lead author on the study. “As we embark upon greater exploitation of this vast environment and start thinking about conserving its resources, it is imperative to know what this habitat already does for us.”

“Our analysis is an effort to begin to summarize what the deep sea provides to humans because we take it for granted or simply do not know that the deep sea does anything to shape our daily lives,” he added. “The truth is that the deep sea affects us, whether we live on the coast or far from the ocean – and its impact on the globe is pervasive.”

The deep sea is important to many critical processes that affect the Earth’s climate, including acting as a “sink” for greenhouse gases – helping offset the growing amounts of carbon dioxide emitted into the atmosphere. It also regenerates nutrients through upwelling that fuel the marine food web in productive coastal systems such as the Pacific Northwest of the United States, Chile and others. Increasingly, fishing and mining industries are going deeper and deeper into the oceans to extract natural resources.

“One concern is that many of these areas are in international waters and outside of any national jurisdiction,” noted Thurber, an assistant professor (senior research) in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. “Yet the impacts are global, so we need a global effort to begin protecting and managing these key, albeit vast, habitats.”

Fishing is an obvious concern, the scientists say. Advances in technology have enabled commercial fisheries to harvest fish at increasing depths – an average of 62.5 meters deeper every decade, according to fisheries scientists. This raises a variety of potential issues.

“The ability to fish deeper is shifting some fisheries to deeper stocks, and opening up harvests of new species,” Thurber said. “In some local cases, individual fisheries are managed aggressively, but due to how slow the majority of the fish grow in the deep, some fish populations are still in decline – even with the best management practices.”

The orange roughy off New Zealand, for instance, is both a model of effective and conservation-based management, yet its populations continue to decline, though at a slower rate than they would have experienced without careful management, Thurber noted.

“We also have to be concerned about pollution that makes its way from our continental shelves into the deep sea,” he added. “Before it was ‘out of sight, out of mind.’  However, some of the pollution can either make it into the fish that we harvest, or harm the fishers that collect the fish for us. It is one of the reasons need to identify how uses of the deep sea in the short term can have long-term consequences. Few things happen fast down there.”

Mining is a major threat to the deep sea, the researchers point out in their analysis. In particular, the quest for rare earth and metal resources, which began decades ago, has skyrocketed in recent years because of their increased use in electronics, and because of dwindling or limited distribution of supplies on land. Mining the deep ocean for manganese nodules, for example – which are rich in nickel – requires machines that may directly impact large swaths of the seafloor and send up a sediment plume that could potentially affect an even larger area, the scientists note.

These mining resources are not limited to muddy habitats, Thurber pointed out. Massive sulfides present at hydrothermal vents are another resource targeted by mining interests.

“The deep sea has been an active area for oil and gas harvesting for many years,” he said, “yet large reservoirs of methane and other potential energy sources remain unexploited. In addition to new energy sources, the potential for novel pharmaceuticals is also vast.

“There are additional threats to these unique habitats, including ocean acidification, warming temperatures and possible changes to ocean circulation through climate change.”

The next step, the researchers say, is to attach an economic value to both the services provided by the deep sea – and the activities that may threaten those services.

“What became clear as we put together this synopsis is that there is vast potential for future resources but we already benefit greatly through this environment,” Thurber said. “”What this means is that while the choices to harvest or mine will be decided over the coming decades, it is important to note that the stakeholders of this environment represent the entire world’s population.”

“The Bible, the Koran, the Torah, and early Greek texts all reference the deep sea,” he added. “Maybe it’s time for all of us to take a closer look at what it has to offer and decide if and how we protect it.”

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Andrew Thurber, 541-737-4500; athurber@coas.oregonstate.edu

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Strategies identified to improve oral contraceptive success with obese women

PORTLAND, Ore. – The findings of a new study suggest two ways to effectively address the problem that birth control pills may not work as well in obese women, compared to women of a normal body mass index.

Birth control pills are a one-size-fits-all method, researchers say, but as the population has increased in weight, concern has grown about how well the pill works for obese women. Studies have consistently found that obesity has a negative impact on drug levels in the body, which may in turn affect how well the pill prevents pregnancy. 

“Birth control pills have been shown in a large population study to fail at a higher rate in women who are obese,” said Ganesh Cherala, an assistant professor in the Oregon State University/Oregon Health & Science University College of Pharmacy.

“Our original studies were focused on why this might occur,” Cherala said, “and we found that obesity changes how a woman’s body clears contraceptive hormones.”

It takes longer for the pill to reach a steady state level in obese women, with possible impacts on efficacy of the birth control, and putting them at greater risk for a pill failure if they forget to take a pill or take it later.

In order to offset these changes, Cherala and Dr. Alison Edelman, an associate professor of obstetrics and gynecology at Oregon Health & Science University, studied two alternative strategies. They found that either a slight increase in the pill dose, from a very low dose to a low dose pill; or using the pill continuously without a “period week” off, appeared to counteract the changes that obesity causes.

This, in turn, may provide improved pregnancy prevention for women of differing weights who use the pill, the researchers said. Their work is published in Contraception, a professional journal, and was supported by the National Institutes of Health.

“Since oral contraception remains one of the most popular forms of birth control in the United States and the majority of our population is obese or overweight, it’s important to find methods of contraception that work for all women, no matter what their weight,” Edelman said.

“The strategies that we studied can be, and are currently being used by women, but now we know that they help to counteract the adverse effects of weight on contraceptive hormones,” she said.

For obese women, simply shifting to an alternative form of birth control is an option, the researchers said. But they also pointed out that oral contraceptives are the most preferred form of birth control and that a woman’s individual preference influences her adherence and continuation with any method.

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Ganesh Cherala, 503-418-0447

Synchronization of North Atlantic, North Pacific preceded abrupt warming, end of ice age

CORVALLIS, Ore. – Scientists have long been concerned that global warming may push Earth’s climate system across a “tipping point,” where rapid melting of ice and further warming may become irreversible – a hotly debated scenario with an unclear picture of what this point of no return may look like.

A newly published study by researchers at Oregon State University probed the geologic past to understand mechanisms of abrupt climate change. The study pinpoints the emergence of synchronized climate variability in the North Pacific Ocean and the North Atlantic Ocean a few hundred years before the rapid warming that took place at the end of the last ice age about 15,000 years ago.

The study suggests that the combined warming of the two oceans may have provided the tipping point for abrupt warming and rapid melting of the northern ice sheets.

Results of the study, which was funded by the National Science Foundation, appear this week in Science.

This new discovery by OSU researchers resulted from an exhaustive 10-year examination of marine sediment cores recovered off southeast Alaska where geologic records of climate change provide an unusually detailed history of changing temperatures on a scale of decades to centuries over many thousands of years.

“Synchronization of two major ocean systems can amplify the transport of heat toward the polar regions and cause larger fluctuations in northern hemisphere climate,” said Summer Praetorius, a doctoral student in marine geology at Oregon State and lead author on the Science paper. “This is consistent with theoretical predictions of what happens when Earth’s climate reaches a tipping point.”

“That doesn’t necessarily mean that the same thing will happen in the future,” she pointed out, “but we cannot rule out that possibility.”

The study found that synchronization of the two regional systems began as climate was gradually warming. After synchronization, the researchers detected wild variability that amplified the changes and accelerated into an abrupt warming event of several degrees within a few decades.

“As the systems become synchronized, they organized and reinforced each other, eventually running away like screeching feedback from a microphone,” said Alan Mix, a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences and co-author on the paper. “Suddenly you had the combined effects of two major oceans forcing the climate instead of one at a time.”

“The example that we uncovered is a cause for concern because many people assume that climate change will be gradual and predictable,” Mix added. “But the study shows that there can be vast climate swings over a period of decades to centuries. If such a thing happened in the future, it could challenges society’s ability to cope.”

What made this study unusual is that the researchers had such a detailed look at the geologic record. While modern climate observations can be made every day, the length of instrumental records is relatively short – typically less than a century. In contrast, paleoclimatic records extend far into the past and give good context for modern changes, the researchers say. However, the resolution of most paleo records is low, limited to looking at changes that occur over thousands of years.

In this study, the researchers examined sediment cores taken from the Gulf of Alaska in 2004 during an expedition led by Mix. The mountains in the region are eroding so fast that sedimentation rates are “phenomenal,” he said. “Essentially, this rapid sedimentation provides a ‘climate tape recorder’ at extremely high fidelity.”

Praetorius then led an effort to look at past temperatures by slicing the sediment into decade-long chunks spanning more than 8,000 years – a laborious process that took years to complete. She measured ratios of oxygen isotopes trapped in fossil shells of marine plankton called foraminifera. The isotopes record the temperature and salinity of the water where the plankton lived.

When the foraminifera died, their shells sank to the sea floor and were preserved in the sediments that eventually were recovered by Mix’s coring team.

The researchers then compared their findings with data from the North Greenland Ice Core Project to see if the two distinct high-latitude climate systems were in any way related.

Most of the time, the two regions vary independently, but about 15,500 years ago, temperature changes started to line up and then both regions warmed abruptly by about five degrees (C) within just a few decades. Praetorius noted that much warmer ocean waters likely would have a profound effect on northern-hemisphere climates by melting sea ice, warming the atmosphere and destabilizing ice sheets over Canada and Europe.

A tipping point for climate change “may be crossed in an instant,” Mix noted, “but the actual response of the Earth’s system may play out over centuries or even thousands of years during a period of dynamic adjustment.”

“Understanding those dynamics requires that we look at examples from the past,” Mix said. “If we really do cross such a boundary in the future, we should probably take a long-term perspective and realize that change will become the new normal. It may be a wild ride.”

Added Praetorius: “Our study does suggest that the synchronization of the two major ocean systems is a potential early warning system to begin looking for the tipping point.”

Media Contact: 
Source: 

Summer Praetorius, 541-737-6159, spraetorius@coas.oregonstate.edu; Alan Mix, 541-737-5212, amix@coas.oregonstate.edu

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15-year analysis of blue whale range off California finds conflict with shipping lanes

NEWPORT, Ore. – A comprehensive 15-year analysis of the movements of satellite-tagged blue whales off the West Coast of the United States found that their favored feeding areas are bisected by heavily used shipping lanes, increasing the threat of injury and mortality.

The researchers note that moving the shipping lanes off Los Angeles and San Francisco to slightly different areas – at least, during summer and fall when blue whales are most abundant – could significantly decrease the probability of ships striking the whales. A similar relocation of shipping lanes in the Bay of Fundy off eastern Canada lowered the likelihood of vessels striking endangered right whales an estimated 80 percent.

Results of the study – which was supported by the Office of Naval Research, the National Geographic Society, the National Science Foundation, private gifts to the Oregon State University Marine Mammal Institute and others – are being published this week in the journal PLOS ONE.

The analysis is the most comprehensive study of blue whales movements ever conducted. It was led by researchers at Oregon State University’s Marine Mammal Institute, who tracked the movement of blue whales off the West Coast to identify important habitat areas and environmental correlates, and subsequently to understand the timing of their presence near major ports and shipping traffic.

“The main areas that attract blue whales are highly productive, strong upwelling zones that produce large amounts of krill – which is pretty much all that they eat,” said Ladd Irvine, a researcher with OSU’s Marine Mammal Institute and lead author on the PLOS ONE study. “The whales have to maximize their food intake during the summer before they migrate south for the winter, typically starting in mid-October to mid-November.”

“It appears that two of their main foraging areas are coincidentally crossed by shipping lanes,” Irvine added.

In their study, the researchers attached transmitters to 171 blue whales off California at different times between 1993 and 2008 and tracked their movements via satellite. Their study looked at seasonal as well as individual differences in whale distribution, documenting a high degree of variability – but also a strong fidelity to the upwelling zones that coincide with ship traffic to and from the major ports of Los Angeles and San Francisco.

Blue whales can grow to the length of a basketball court, weigh as much as 25 large elephants combined, and their mouths could hold 100 people, though their diet is primarily krill – tiny shrimp-like creatures less than two inches in length. The blue whale is the largest creature to ever inhabit the Earth, yet little was known about their range or where they went to breed until Oregon State’s Bruce Mate led a series of tracking studies featured in the popular 2009 National Geographic documentary, “Kingdom of the Blue Whale.”

An estimated 2,500 of the world’s 10,000 blue whales spend time in the waters off the West Coast of the Americas and are known as the eastern North Pacific population. The huge whales can travel from the Gulf of Alaska all the way down to an area near the equator known as the Costa Rica Dome.

The majority of the population spends the summer and fall in the waters off the U.S. West Coast, with the areas most heavily used by the tagged whales occurring off California’s Santa Barbara and San Francisco, which puts them in constant peril from ship strikes.

“During one year, while we were filming the documentary, five blue whales were hit off of southern California during a seven-week period,” said Mate, who directs the Marine Mammal Institute at OSU’s Hatfield Marine Science Center in Newport, Ore. “Blue whales may not be as acoustically aware as species that rely on echolocation to find prey and there is some evidence that the location of the engines in the rear of the ship creates something of an acoustic shadow in front of them, making it hard for whales to hear the ship coming.

“Putting some kind of noise deterrent on the ships isn’t really an option, however,” Mate added. “You don’t really want to drive endangered whales out of their prime habitat and best feeding locations.”

Moving the shipping lanes would not be unprecedented, the researchers note. Scientists brought concerns about right whale ship strikes in the Bay of Fundy to the International Maritime Organization, and the industry led the effort to modify shipping lanes in the North Atlantic more than a decade ago.

Daniel Palacios, also a co-author on the paper and a principal investigator with OSU’s Marine Mammal Institute, said vessel traffic between Santa Barbara and Los Angeles moved south of its current location in the past to comply with the California Clear Air Act, but shifted back to its current location after getting an exemption to the legislation.

“It is not often that research results are so applicable to a policy decision.” Palacios said, “It’s not really our place to make management decisions, but we can inform policy-makers and in this case it is pretty straightforward. You will eliminate many of the ship strikes on blue whales by moving the shipping lanes south of the northern Channel Islands.”

The solution for the San Francisco area is similar, the researchers note, though not quite as simple. Three separate shipping lanes are used in the region and all cross through the home range and core areas of blue whales tagged in this study.

“We did find that the northernmost shipping lanes crossed the area that was most heavily used by tagged whales,” Irvine noted. “Restricting use of the northern lane during the summer and fall when more whales are present is one option; another would be to extend one lane further offshore before separating it into different trajectories, minimizing the overlap of the shipping lanes with the areas used by blue whales.”

The National Oceanic and Atmospheric Administration is planning a review of shipping lanes in the southern California area, which will be informed by this study. A variety of stakeholders must be consulted, however, before any changes are implemented.

Other funding sources for this study over the years including the TOPP Program (Tagging of Pacific Pelagics), the OSU Marine Mammal Institute Endowment, the Alfred P. Sloan Foundation, the Packard Foundation, NASA, the U.S. Geological Survey, the National Park Service, U.S. Fish and Wildlife Service and the Smithsonian Institution.

Media Contact: 
Source: 

Ladd Irvine, 541-867-0394, ladd.irvine@oregonstate.edu; Bruce Mate, 541-867-0202, bruce.mate@oregonstate.edu; Daniel Palacios, 541-990-2750, Daniel.Palacios@oregonstate.edu

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