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New study finds “nighttime heat waves” increasing in Pacific Northwest

CORVALLIS, Ore. – A new study has found that heat waves are increasing in the western portions of the Pacific Northwest, but not the kind most people envision, with scorching hot days of temperatures reaching triple digits.

These heat waves occur at night.

Researchers documented 15 examples of “nighttime heat waves” from 1901 through 2009 and 10 of those have occurred since 1990. Five of them took place during a four-year period from 2006-09. And since the study was accepted for publication in the Journal of Applied Meteorology and Climatology, another nighttime heat wave took place at the end of this June, the authors point out.

“Most people are familiar with daytime heat waves, when the temperatures get into the 100s and stay there for a few days,” said Kathie Dello, deputy director of the Oregon Climate Service at Oregon State University and a co-author on the study. “A nighttime heat wave relates to how high the minimum temperature remains overnight.

“Daytime events are usually influenced by downslope warming over the Cascade Mountains, while nighttime heat waves seem to be triggered by humidity,” said Dello, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Elevated low-level moisture at night tends to trap the heat in.”

In their study, Dello and co-authors Karin Bumbaco and Nicholas Bond from the University of Washington defined heat waves as three consecutive days of temperatures at the warmest 1 percentile over the past century. Using that standard criterion, they documented 13 examples of daytime heat waves during the time period from 1901 to 2009. Only two of those occurred in the last 20 years.

In contrast, nighttime heat waves have been clustered over the past two decades, with what appears to be accelerating frequency. A warming climate suggests the problem may worsen, studies suggest.

“If you look at nighttime temperatures in Oregon and compared them to say the Midwest, people there would laugh at the concept of a Pacific Northwest heat wave,” Dello said. “However, people in the Midwest are acclimated to the heat while in the Northwest, they are not. People in other regions of the country may also be more likely to have air conditioning in their homes.

On occasion, daytime and nighttime heat waves coincide, Dello said, as happened in 2009 when temperatures in the Pacific Northwest set all-time records in Washington (including 103 degrees at SeaTac), and temperatures in Oregon surpassed 105 degrees in Portland, Eugene, Corvallis and Medford. It was the second most-intense daytime heat wave in the last century, but lasted only three days by the 1 percentile definition.

However, that same stretch of hot weather in 2009 results in a nighttime heat wave that extended eight days, by far the longest stretch since records were kept beginning in 1901.

The latest nighttime heat wave began in late June of this year, and continued into early July, Dello said.

“Like many nighttime heat waves, a large high-pressure ridge settled in over the Northwest, while at the same time, some monsoonal moisture was coming up from the Southwest,” she pointed out. “The high swept around and grabbed enough moisture to elevate the humidity and trap the warm air at night.”

Dello frequently provides weather facts and historical data via Twitter at: www.twitter.com/orclimatesvc.

The Oregon Climate Change Research Institute is supported by the state of Oregon, U.S. Department of the Interior, National Oceanic and Atmospheric Association, and other agencies.

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Kathie Dello, 541-737-8927

Scientists outline long-term sea-level rise in response to warming of planet

CORVALLIS, Ore. – A new study estimates that global sea levels will rise about 2.3 meters, or more than seven feet, over the next several thousand years for every degree (Celsius) the planet warms.

This international study is one of the first to combine analyses of four major contributors to potential sea level rise into a collective estimate, and compare it with evidence of past sea-level responses to global temperature changes.

Results of the study, funded primarily by the National Science Foundation and the German Federal Ministry of Education and Research, are being published this week in the Proceedings of the National Academy of Sciences.

“The study did not seek to estimate how much the planet will warm, or how rapidly sea levels will rise,” noted Peter Clark, an Oregon State University paleoclimatologist and author on the PNAS article. “Instead, we were trying to pin down the ‘sea-level commitment’ of global warming on a multi-millennial time scale. In other words, how much would sea levels rise over long periods of time for each degree the planet warms and holds that warmth?”

“The simulations of future scenarios we ran from physical models were fairly consistent with evidence of sea-level rise from the past,” Clark added. “Some 120,000 years ago, for example, it was 1-2 degrees warmer than it is now and sea levels were about five to nine meters higher. This is consistent with what our models say may happen in the future.”

Scientists say the four major contributors to sea-level rise on a global scale will come from melting of glaciers, melting of the Greenland ice sheet, melting of the Antarctic ice sheet, and expansion of the ocean itself as it warms. Several past studies have examined each of these components, the authors say, but this is one of the first efforts at merging different analyses into a single projection.

The researchers ran hundreds of simulations through their models to calculate how the four areas would respond to warming, Clark said, and the response was mostly linear. The amount of melting and subsequent sea-level response was commensurate with the amount of warming. The exception, he said, was in Greenland, which seems to have a threshold at which the response can be amplified.

“As the ice sheet in Greenland melts over thousands of years and becomes lower, the temperature will increase because of the elevation loss,” Clark said. “For every 1,000 meters of elevation loss, it warms about six degrees (Celsius). That elevation loss would accelerate the melting of the Greenland ice sheet.”

In contrast, the Antarctic ice sheet is so cold that elevation loss won’t affect it the same way. The melting of the ice sheet there comes primarily from the calving of icebergs, which float away and melt in warmer ocean waters, or the contact between the edges of the ice sheet and seawater.

In their paper, the authors note that sea-level rise in the past century has been dominated by the expansion of the ocean and melting of glaciers. The biggest contributions in the future may come from melting of the Greenland ice sheet, which could disappear entirely, and the Antarctic ice sheet, which will likely reach some kind of equilibrium with atmospheric temperatures and shrink significantly, but not disappear.

“Keep in mind that the sea level rise projected by these models of 2.3 meters per degree of warming is over thousands of years,” emphasized Clark, who is a professor in Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences. “If it warms a degree in the next two years, sea levels won’t necessarily rise immediately. The Earth has to warm and hold that increased temperature over time.

“However, carbon dioxide has a very long time scale and the amounts we’ve emitted into the atmosphere will stay up there for thousands of years,” he added. “Even if we were to reduce emissions, the sea-level commitment of global warming will be significant.”

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Peter Clark, cell phone: 541-740-5237 (clarkp@geo.oregonstate.edu)

Researchers document acceleration of ocean denitrification during deglaciation

CORVALLIS, Ore. – As ice sheets melted during the deglaciation of the last ice age and global oceans warmed, oceanic oxygen levels decreased and “denitrification” accelerated by 30 to 120 percent, a new international study shows, creating oxygen-poor marine regions and throwing the oceanic nitrogen cycle off balance.

By the end of the deglaciation, however, the oceans had adjusted to their new warmer state and the nitrogen cycle had stabilized – though it took several millennia. Recent increases in global warming, thought to be caused by human activities, are raising concerns that denitrification may adversely affect marine environments over the next few hundred years, with potentially significant effects on ocean food webs.

Results of the study have been published this week in the journal Nature Geoscience. It was supported by the National Science Foundation.

“The warming that occurred during deglaciation some 20,000 to 10,000 years ago led to a reduction of oxygen gas dissolved in sea water and more denitrification, or removal of nitrogen nutrients from the ocean,” explained Andreas Schmittner, an Oregon State University oceanographer and author on the Nature Geoscience paper. “Since nitrogen nutrients are needed by algae to grow, this affects phytoplankton growth and productivity, and may also affect atmospheric carbon dioxide concentrations.”

“This study shows just what happened in the past, and suggests that decreases in oceanic oxygen that will likely take place under future global warming scenarios could mean more denitrification and fewer nutrients available for phytoplankton,” Schmittner added.

In their study, the scientists analyzed more than 2,300 seafloor core samples, and created 76 time series of nitrogen isotopes in those sediments spanning the past 30,000 years. They discovered that during the last glacial maximum, the Earth’s nitrogen cycle was at a near steady state. In other words, the amount of nitrogen nutrients added to the oceans – known as nitrogen fixation – was sufficient to compensate for the amount lost by denitrification.

A lack of nitrogen can essentially starve a marine ecosystem by not providing enough nutrients. Conversely, too much nitrogen can create an excess of plant growth that eventually decays and uses up the oxygen dissolved in sea water, suffocating fish and other marine organisms.

Following the period of enhanced denitrification and nitrogen loss during deglaciation, the world’s oceans slowly moved back toward a state of near stabilization. But there are signs that recent rates of global warming may be pushing the nitrogen cycle out of balance.

“Measurements show that oxygen is already decreasing in the ocean,” Schmittner said “The changes we saw during deglaciation of the last ice age happened over thousands of years. But current warming trends are happening at a much faster rate than in the past, which almost certainly will cause oceanic changes to occur more rapidly.

“It still may take decades, even centuries to unfold,” he added.

Schmittner and Christopher Somes, a former graduate student in the OSU College of Earth, Ocean, and Atmospheric Sciences, developed a model of nitrogen isotope cycling in the ocean, and compared that with the nitrogen measurements from the seafloor sediments. Their sensitivity experiments with the model helped to interpret the complex patterns seen in the observations.

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Andreas Schmittner, 541-737-9952; aschmittner@coas.oregonstate.edu

OSU geographer to receive international prize for mediation

CORVALLIS, Ore. – An Oregon State University faculty member has won a major international prize for his mediation efforts in water conflicts.

Aaron Wolf, a geography professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences, has been named a 2013 recipient of Il Monito del Giardino (The Warning from the Garden) Award by the Bardini and Peyron Monumental Parks Foundation of Florence, Italy.

The honor is given to persons who have distinguished themselves internationally in safeguarding the environment and raising awareness of ecological issues. The 2012 recipient was Jane Goodall.

Wolf will receive his award next week June in Florence.

The scientific committee cited Wolf’s involvement in striving for more democratic access to the world’s water sources. “The value of his work has come to be recognized on the world stage, mediation work in controversies relative to water’s being at the center of the geopolitical scences that are very delicate, such as that of the Mideast.”

Wolf has traveled throughout the world as both a scientist and a mediator in the area of water conflicts. He has been a consultant to the U.S. Department of State, the U.S. Agency for International Development, the World Bank, and numerous governments.

He directs the Program in Water Conflict Management and Transformation, and developed the Transboundary Freshwater Dispute database, which includes a compilation of 400 water-related treaties as well as information on water conflicts and resolution.

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Aaron Wolf, 541-737-2722; wolf@geo.oregonstate.edu

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Natural Resources Leadership Academy 2012
Aaron Wolf

Occasional raindrops do little to address drying state

CORVALLIS, Ore. – When Oregonians can rototill their gardens in March, but then have to water their lawns all throughout April and May, you know it’s drier than usual.

Experts say that through May 10, it has been the driest start to the year on record at the Eugene and Salem airport weather stations, and the second driest start at Hyslop Farm in Corvallis and the Medford Airport. This is the third driest start to the year for the Portland Airport station.

“We’ve seen some pretty drastic swings from very wet to very dry over the past year,” said Oregon State University’s Kathie Dello, who is the deputy director of the Oregon Climate Service at OSU. “The whole West Coast has been abnormally dry. We’ve had some strong high pressure ridging, which means the storm track is sent to our north.

“When it does that, we get weather that generally results in hot days and cool nights,” Dello said, “and it is usually quite dry.”

The spring of 2012 – from March to May – was the fourth wettest on record statewide, and then things dried up quickly. The summer July to September period was the second driest on record. But the fall October to December period saw above-normal precipitation, before the transition to this spring’s dry conditions.

“It’s been pretty topsy-turvy,” Dello said. “On one hand, we built up a nice snowpack through November and December in the central and northern Cascades, but abnormally warm temperatures are melting that quickly.”

More than 91 percent of Oregon is considered abnormally dry for this time of year, Dello said, citing the U.S. Drought Monitor. The NOAA Climate Prediction Center shows that the odds favor the dry trend continuing into July.

“The biggest concern when that happens is warm, dry ground and early melting of snow,” Dello said. “That equates to fire danger. The National Interagency Fire Center is saying that fire season may begin weeks earlier than normal this year.

“And, of course, dry conditions are a concern for farmers, stream health and fish,” she added. “We have seen occasional bouts of cloudiness and sprinkles, but not enough to chase the overall pattern of dryness.”

For the record:

  • Through May 10, the Eugene Airport has received just 6.54 inches of rain, which is 14.08 inches below normal. It is the driest on record dating back to 1940.
  • The Salem Airport has had 7.65 inches of rain, driest on record back to 1928, and 9.67 inches below normal.
  • The Corvallis Hyslop station has received 8.27 inches of rain, second driest on record back to 1893 and 10.59 inches below normal. The driest on record was in 2001, when it got just 7.98 inches.
  • Medford Airport has received a scant 3.05 inches, which is 4.48 inches below normal in records dating back to 1928. The driest start to a year on record was in 1992 with 2.99 inches.
  • Portland Airport has logged 8.3 inches of precipitation, 6.55 inches before normal and third driest since 1942. The record year was in 1985, with 6.0 inches.

Weather-lovers can learn more about Oregon weather by following Dello on Twitter at: www.twitter.com/orclimatesvc. The state is also looking for volunteers to collect precipitation data. For more information, go to http://www.cocorahs.org/.

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Kathie Dello, 541-737-8927

Study traces origin of cirrus clouds primarily to mineral dust and metals

CORVALLIS, Ore. – Researchers studying the origin of cirrus clouds have found that these thin, wispy trails of ice crystals are formed primarily on dust particles and some unusual combinations of metal particles – both of which may be influenced by human activities.

The findings are important, scientists say, because cirrus clouds cover as much as one-third of the Earth and play an important role in global climate. Depending on altitude and the number and size of ice crystals, cirrus clouds can cool the planet by reflecting incoming solar radiation – or warm it by trapping outgoing heat.

However, what the net effect is, and how humans impact it, is still unclear.

Results of the study, which was funded by NASA and the National Science Foundation, were published this week in the journal Science.

“Cirrus clouds are complicated but the important message is that dust and certain metals provide the seeds for a majority of the ice crystals that form the clouds,” said Cynthia Twohy, an Oregon State University atmospheric scientist and co-author on the study. “Other particle types – including bacteria and soot from human-produced combustion or natural sources – don’t seem to contribute much to the nuclei of cirrus crystals.

“These biological particles may be important in the formation of lower altitude clouds,” added Twohy, who is a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “But they were surprisingly absent from the particles we sampled from cirrus clouds.”

During the study, led by scientists at the Massachusetts Institute of Technology and the National Oceanic and Atmospheric Administration, the researchers conducted flight missions from 2002 to 2011 over North America and Central America at 20,000 to 50,000 feet elevation, where cirrus clouds often form. As their planes flew through the clouds, researchers captured and heated the ice crystals, which then evaporated, leaving behind a tiny kernel that they analyzed using an onboard mass spectrometer.

Despite the length of the study and its different geographic locations, the researchers found similar outcomes: About 60 percent of the cloud particles they analyzed could be traced to mineral dust blown into the atmosphere, or to metallic aerosols.

“Mineral dust can occur naturally,” Twohy said, “or it can be influenced by human activities. Certainly the major deserts like the Sahara and Gobi are enormous sources of mineral dust. But agriculture, over-grazing and climate and land-use changes can also contribute.”

Twohy said the scientists have not yet traced the origin of the dust to see how much of it came from natural versus anthropogenic causes. The metallic aerosols, she added, are unusual and may be easier to trace to specific sources. Containing elements like lead, zinc, tin and copper, they appear to be from industrial activities, according to other scientists in the study.

“As the climate warms, it is possible that we will see an expansion of desert lands, which could lead to even more dust entering the atmosphere,” Twohy said. “That could create more cirrus clouds, but what that means in terms of warming or cooling is unsure and an area for future research.”

An expert in cloud formation, Twohy has been involved in some 30 different aircraft missions over the years to understand the composition and characteristics of clouds and how they are influenced by pollution. She has studied clouds in North America, Central America, South America, Africa, the Southern Ocean and the Indian Ocean.

“At lower altitudes, clouds are known to be influenced by pollution – especially near cities,” Twohy said. “They have more droplets, they reflect more light and they rain less. The impacts of cirrus clouds on climate are much more complex. But this gives us a starting point because we now have a better understanding of the particle types and mechanisms that lead to their formation.”

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Cynthia Twohy, 541-737-5690

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College of Earth, Ocean, and Atmospheric Sciences

About the OSU College of Earth, Ocean, and Atmospheric Sciences: CEOAS is internationally recognized for its faculty, research and facilities, including state-of-the-art computing infrastructure to support real-time ocean/atmosphere observation and prediction. The college is a leader in the study of the Earth as an integrated system, providing scientific understanding to address complex environmental challenges

Reconstruction of temperature history shows significance of recent warming

 

Editor’s Note: In light of the many questions the authors of this study have received about their work, they have posted an FAQ that lays out how they gathered and analyzed data and reached conclusions. http://www.realclimate.org/index.php/archives/2013/03/response-by-marcott-et-al/

 

CORVALLIS, Ore. – Using data from 73 sites around the world, scientists have been able to reconstruct Earth’s temperature history back to the end of the last Ice Age, revealing that the planet today is warmer than it has been during 70 to 80 percent of the time over the last 11,300 years.

Of even more concern are projections of global temperature for the year 2100, when virtually every climate model evaluated by the Intergovernmental Panel on Climate Change (IPCC) shows that temperatures will exceed the warmest temperatures during that 11,300-year period known as the Holocene – under all plausible greenhouse gas emission scenarios.

Results of the study, by researchers at Oregon State University and Harvard University, were published this week in the journal Science. It was funded by the National Science Foundation’s Paleoclimate Program.

Lead author Shaun Marcott, a post-doctoral researcher in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences, noted that previous research on past global temperature change has largely focused on the last 2,000 years. Extending the reconstruction of global temperatures back to the end of the last Ice Age puts today’s climate into a larger context.

“We already knew that on a global scale, Earth is warmer today than it was over much of the past 2,000 years,” Marcott said. “Now we know that it is warmer than most of the past 11,300 years. This is of particular interest because the Holocene spans the entire period of human civilization.”

Peter Clark, an OSU paleoclimatologist and co-author on the Science article, said many previous temperature reconstructions were regional in nature and were not placed in a global context. Marcott led the effort to combine data from 73 sites around the world, providing a much broader perspective.

“When you just look at one part of the world, the temperature history can be affected by regional climate processes like El Nino or monsoon variations,” noted Clark. “But when you combine the data from sites all around the world, you can average out those regional anomalies and get a clear sense of the Earth’s global temperature history.”

What that history shows, the researchers say, is that over the past 5,000 years, the Earth on average cooled about 1.3 degrees (Fahrenheit) – until the past 100 years, when it warmed ̴ 1.3 degrees (F). The largest changes were in the northern hemisphere, where there are more land masses and greater human populations.

Climate models project that global temperature will rise another 2.0 to 11.5 degrees (F) by the end of this century, largely dependent on the magnitude of carbon emissions. “What is most troubling,” Clark said, “is that this warming will be significantly greater than at any time during the past 11,300 years.”

Marcott said that one of the natural factors affecting global temperatures over the past 11,300 years is gradual change in the distribution of solar insolation associated with Earth’s position relative to the sun.

“During the warmest period of the Holocene, the Earth was positioned such that Northern Hemisphere summers warmed more,” Marcott said. “As the Earth’s orientation changed, Northern Hemisphere summers became cooler, and we should now be near the bottom of this long-term cooling trend – but obviously, we are not.”

Clark said that other studies, including those outlined in past IPCC reports, have attributed the warming of the planet over the past 50 years to anthropogenic, or human-caused activities – and not solar variability or other natural causes.

“The last century stands out as the anomaly in this record of global temperature since the end of the last ice age,” said Candace Major, program director in the National Science Foundation’s Division of Ocean Sciences, which co-funded the research with NSF’s Division of Atmospheric and Geospace Sciences. “This research shows that we’ve experienced almost the same range of temperature change since the beginning of the industrial revolution as over the previous 11,000 years of Earth history – but this change happened a lot more quickly.”

The research team, which included Jeremy Shakun of Harvard University and Alan Mix of Oregon State, primarily used fossils from ocean sediment cores and terrestrial archives to reconstruct the temperature history. The chemical and physical characteristics of the fossils – including the species as well as their chemical composition and isotopic ratios – provide reliable proxy records for past temperatures by calibrating them to modern temperature records.

Using data from 73 sites around the world allows a global picture of the Earth’s history and provides new context for climate change analysis.

“The Earth’s climate is complex and responds to multiple forcings, including CO2 and solar insolation,” Marcott said. “Both of those changed very slowly over the past 11,000 years. But in the last 100 years, the increase in CO2 through increased emissions from human activities has been significant. It is the only variable that can best explain the rapid increase in global temperatures.”

Marcott received his Ph.D. in geology in 2011 from OSU.

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Shaun Marcott, 541-737-1209

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Ocean sediment collection Ice core West Antarctica

NSF selects OSU to lead project rejuvenating U.S. research fleet

CORVALLIS, Ore. – The National Science Foundation has notified Oregon State University that it will be the lead institution on a project to finalize the design and coordinate the construction of as many as three new coastal research vessels to bolster the marine science research capabilities of the United States.

OSU initially will receive nearly $3 million to coordinate the design phase of the project – and if funds are appropriated for all three vessels, the total grant is projected to reach $290 million over 10 years. The final number constructed, and the geographic positioning of these vessels, will be determined by the National Science Foundation based on geographic scientific requirements and availability of funding.

If all three vessels are built, it is likely that one would be positioned on the East Coast, West Coast and Gulf Coast, officials say.

A project team led by Oregon State’s College of Earth, Ocean, and Atmospheric Sciences will finalize the design for the 175-foot long, technically enhanced Regional Class ships, select a shipyard, oversee construction, and coordinate the system integration, testing, commissioning and acceptance, and transition to operations.

“These will be floating, multi-use laboratories that are flexible and can be adapted for different scientific purposes, yet are more seaworthy and environmentally ‘green’ than previous research vessels,” said Mark Abbott, dean of the OSU College of Earth, Ocean, and Atmospheric Sciences. “These ships will be used to address critical issues related to climate change, ocean circulation, natural hazards, human health, and marine ecosystems.”

OSU vice president for research Rick Spinrad, who previously directed research programs for the U.S. Navy and the National Oceanic and Atmospheric Administration (NOAA), said the new vessels would “revitalize and transform” coastal ocean science in the United States.

“Many of the most pressing issues facing our oceans are in these coastal regions, including acidification, hypoxia, tsunami prediction, declining fisheries, and harmful algal blooms,” Spinrad said. “Because of their flexibility, these new vessels will attract a broad range of users and will become ideal platforms to training early-career scientists and mariners.”

The project had the support of Oregon Gov. John Kitzhaber’s Office, noted OSU President Ed Ray, who said the university will benefit from the process long before the first ship hits the water in 2019 or 2020.

“What is really unique about this project is that it will involve faculty from engineering and business, who will join their oceanography colleagues on the design and construction elements – and provide unbelievable training opportunities for OSU undergraduate and graduate students interested in project management, marine technology and marine science,” Ray pointed out.

The successful OSU proposal was submitted to the National Science Foundation by Clare Reimers, an oceanography professor, and Demian Bailey, the university’s marine superintendent. As part of that submission, OSU proposed to be the operator of the first vessel. Additional operating institutions will be determined once the total number of vessels to be built is known.

The university now operates the R/V Oceanus, an older research vessel scheduled for retirement about the time the new research vessels will become available.

“The National Science Foundation hasn’t authorized a multi-ship project since the 1970s,” Bailey said, “and these are likely the only ships scheduled by NSF to be built during the next decade – so this is a big deal. The endurance and size of the new ships will be similar to that of Oceanus and (former OSU vessel) Wecoma but they will be much more efficient and have far greater scientific capacity and flexibility.”

Bailey said the new vessels will have advanced dynamic positioning that will help them stay in place in the rugged Pacific Ocean. That is a benefit for launching and retrieving gliders and other autonomous or remotely operated vehicles, conducting precise seafloor mapping, and retrieving moorings and other instrumentation. They also will be much quieter, which will help researchers who use acoustics to study everything from endangered whales to undersea earthquakes and volcanoes.

Reimers said the first phase of the 10-year project will begin in early 2013 with the finalization of the vessel design. A concept design is already in place and the OSU project team will partner with two regional firms – The Glosten Associates in Seattle, Wash., and Science Applications International Corporation in Oregon City – to meet naval architecture, marine design and systems engineering requirements.

“These new vessels will allow scientists at sea to conduct state-of-the-art scientific research from the atmosphere above into the seafloor below our coastal oceans,” Reimers said. “Broader impacts will also be possible because these ships will be equipped with modern telecommunications technologies and sensors to be able to transmit a rich variety of observations to scientists, educators and the public ashore.”

U.S. Sen. Ron Wyden (D-Ore.) praised the project and selection of OSU.

“These research ships will keep the United States in the forefront of coastal ocean science,” Wyden said. “The selection of Oregon State University to design these vessels represents an important investment in our nation’s research infrastructure and adds to the state’s already-growing reputation as a center for marine research and the place that will train the next generation of ocean scientists.”

Fellow Senator Jeff Merkley (D-Ore.) described the announcement as “great news for both Oregon State University and the state of Oregon.”

“Oregon State is on the cutting edge for marine research and it is only fitting that they have received the honor of designing these new research ships,” Merkley said. “I am excited that we will be developing top-notch research into the health of our oceans and the effects of climate change through this targeted investment right here in Oregon.”

History of OSU Research Vessels

1964 – The Department of Oceanography commissions the 180-foot Yaquina

1968 – The Department of Oceanography commissions the 80-foot Cayuse

1975 – The School of Oceanography commissions the 184-foot Wecoma

2000 – The 54-foot Elakha was funded by a Packard Foundation grant to College of Science researchers, and after construction operated by the College of Oceanic and Atmospheric Sciences

2012 – The College of Earth, Ocean, and Atmospheric Sciences takes over operation of the 177-foot Oceanus, formerly operated by Woods Hole Oceanographic Institution.

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Mark Abbott, 541-737-5195

Study finds prey density more important to predators than biomass

Note: The journal article this release is based on can be found at: http://dx.plos.org/10.1371/journal.pone.0053348

CORVALLIS, Ore. – Marine resource managers often gauge the health of species based on overall biomass, but a new study of predator-prey relationships in the Bering Sea found that it isn’t the total number of individuals that predators care about – it’s how densely they are aggregated.

It’s more than searching for an easy meal, the researchers say. Predators need to balance how much energy they expend in searching for food with the caloric and nutrient value of that which they consume. When prey doesn’t aggregate, however, the search for food becomes much more difficult – affecting the health of the predators’ offspring and the vitality of their overall population.

Results of the study were published this week in the journal PLOS ONE. The study was part of the Bering Sea Integrated Ecosystem Research Project, which was funded by the North Pacific Research Board and the National Science Foundation.

“We had to think very differently about these interactions, trying to see the world from the predators’ point of view,” said Kelly Benoit-Bird, an Oregon State University marine ecologist and lead author on the study. “When we first tried to identify good foraging locations for predator species we looked at areas of high prey numbers because it makes sense that they’d be where the food is. But the results didn’t match what we might have expected.

“Predator populations that should have been doing well, based on prey numbers or biomass, were in fact not doing well,” added Benoit-Bird, an associate professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “What we discovered is that smaller aggregations of prey are more attractive to predators if they are sufficiently dense.”

The findings are particularly important, scientists say, because almost all fisheries management is based on biomass – tons of fish – and not how those fish may be distributed in the sea.

In their study, the researchers looked at the feeding behaviors of three co-occurring species in the Bering Sea, all of which consume juvenile pollock or krill – black-legged kittiwakes, thick-billed murres and northern fur seals. When they attempted to find a spatial relationship between these predators and the pollock using areal biomass and numerical abundance, they found little correlation.

However, when they began finding small patches of prey at certain depths and of sufficient density, the predators were there. And though the scientists know why – feeding efficiency – they aren’t sure how.

“To be honest, we aren’t really sure how these predators – which may travel many miles – locate the densest aggregations at depths well below the surface – and often at night,” said Scott Heppell, a fisheries ecologist at Oregon State University and co-author on the PLOS ONE paper. “You wouldn’t think murres and fur seals would have that much in common, but in this case they do.”

“In a way, they’re looking for the same thing that commercial fishing fleets look for – high-quality prey in aggregations dense enough to be economical,” added Heppell, an assistant professor of fisheries and wildlife at OSU.

Benoit-Bird likened the predator-prey link to locating a box of popcorn in a darkened movie theater. You may have to search for it, she noted, but if you find the popcorn box, the payoff will be much more significant than what you might get by stumbling upon individual kernels in the dark that are spread throughout the theater – even though the number of kernels is the same.

That payoff is particularly meaningful for nurturing young, the researchers point out. During their two-year study, the research group tagged and observed female fur seals from St. Paul Island and Bogoslof Island as they swam hundreds of kilometers over a period of 1-2 weeks to gorge on nutrient-rich pollock then return to their homes to nurse pups.

They also tagged and observed adult murres and kittiwakes at St. Paul, St. George and Bogoslof Islands. The birds would capture local prey to feed their chicks during the day, but make numerous long flights at night to gorge on energy-rich, deep-water prey before returning to their nests to feed their chicks.

“It is a trade-off strategy,” said Benoit-Bird, a 2010 recipient of a MacArthur Fellowship. “They feed themselves in one place and nourish their offspring from another.”

This concept of prey “patchiness” can change rapidly, the researchers noted. Pollock aggregated only when the number of individuals in an area reached a certain threshold; below that threshold, they swam as individuals.

“If the population is sufficiently diffuse, the pollock don’t aggregate and that could spell trouble for species that prey upon them,” Heppell said. “A 10 percent shift in the number of fish could change how the entire stock behaves – and have a major impact on the birds, seals and other predators.”

Other authors on the PLOS ONE paper include Brian Battaile, Chad Nordstrom and Andrew Trites of the University of British Columbia; Brian Hoover and Nathan Jones, University of California’s Moss Landing Marine Laboratories; David Irons and Kathy Kuletz of the U.S. Fish and Wildlife Service in Anchorage; and Rosana Paredes, Robert Suryan and Chad Waluk of Oregon State University.

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Kelly Benoit-Bird, 541-737-2063

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