OREGON STATE UNIVERSITY

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Study finds prey distribution, not biomass, key to marine food chain

CORVALLIS, Ore. – A new study has found that each step of the marine food chain is clearly controlled by the trophic level below it – and the driving factor influencing that relationship is not the abundance of prey, but how that prey is distributed.

The importance of the spatial pattern of resources – sometimes called “patchiness” – is gaining new appreciation from ecologists, who are finding the overall abundance of food less important than its density and ease of access to it.

Results of the study are being published this week in the Royal Society journal Biology Letters.

Kelly Benoit-Bird, an Oregon State University oceanographer and lead author on the study, said patchiness is not a new concept, but one that has gained acceptance as sophisticated technologies have evolved to track relationships among marine species.

“The spatial patterns of the resource ultimately determine how the ecosystem functions,” said Benoit-Bird, who received a prestigious MacArthur Fellowship in 2010. “In the past, ecologists primarily used biomass as the determining factor for understanding the food chain, and the story was always rather muddled. We used to think that the size and abundance of prey was what mattered most.

“But patchiness is not only ubiquitous in marine systems, it ultimately dictates the behavior of many animals and their relationships to the environment,” she added.

Benoit-Bird specializes in the relationship of different species in marine ecosystems. In one study in the Bering Sea, she and her colleagues were estimating the abundance of krill, an important food resource for many species. Closer examination through the use of acoustics, however, found that the distribution of krill was not at all uniform – which the researchers say explained why two colonies of fur seals and seabirds were faring poorly, but a third was healthy.

“The amount of food near the third colony was not abundant,” she said, “but what was there was sufficiently dense – and at the right depth – that made it more accessible for predation than the krill near the other two colonies.”

The ability to use acoustics to track animal behavior underwater is opening new avenues to researchers.  During their study in the Bering Sea, Benoit-Bird and her colleagues discovered that they could also use sonar to plot the dives of thick-billed murres, which would plunge up to 200 meters below the surface in search of the krill.

Although the krill were spread throughout the water column, the murres ended up focusing on areas where the patches of krill were the densest.

“The murres are amazingly good at diving right down to the best patches,” Benoit-Bird pointed out. “We don’t know just how they are able to identify them, but 10 years ago, we wouldn’t have known that they had that ability. Now we can use high-frequency sound waves to look at krill, different frequencies to look at murres, and still others to look at squid, dolphins and other animals.

“And everywhere we’ve looked the same pattern occurs,” she added. “It is the distribution of food, not the biomass, which is important.”

An associate professor in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University, Benoit-Bird has received young investigator or early career awards from the Office of Naval Research, the White House and the American Geophysical Union. She also has received honors from the Acoustical Society of America, which has used her as a model scientist in publications aimed at middle school students.

Her work has taken her around the world, including Hawaii where she has used acoustics to study the sophisticated feeding behavior of spinner dolphins. Those studies, she says, helped lead to new revelations about the importance of patchiness.

Ocean physics in the region results in long, thin layers of phytoplankton that may stretch for miles, but are only a few inches thick and a few meters below the surface. Benoit-Bird and her colleagues discovered a layer of zooplankton – tiny animals that feed on the plankton – treading water a meter below to be near the food source. Next up in the food chain were micronekton, larger pelagic fish and crustaceans that would spend the day 600 to 1,000 meters beneath the surface, then come up to the continental shelf at night to target the zooplankton. And the spinner dolphins would emerge at night, where they could reach the depth of the micronekton.

“The phytoplankton were responding to ocean physics,” Benoit-Bird said, “but all of the others in the food chain were targeting their prey by focusing on the densest patches. We got to the point where we could predict with 70 percent accuracy where the dolphins would show up based just on the phytoplankton density – without even considering the zooplankton and micronekton distribution.”

Ocean “patchiness” is not a new concept, Benoit-Bird reiterated, but may have been under-appreciated in importance.

“If you’re a murre that is diving a hundred meters below the surface to find food, you want to maximize the payoff for all of the energy you’re expending,” Benoit-Bird said. “Now we need more research to determine how different species are able to determine where the best patches are.”

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Kelly Benoit-Bird, 541-737-2063

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Dolphins circling prey
Prey density is key

OSU unveils new seafloor mapping of Oregon’s nearshore ocean

CORVALLIS, Ore. – After more than two years of intense field work and digital cartography, researchers have unveiled new maps of the seafloor off Oregon that cover more than half of the state’s territorial waters – a collaborative project that will provide new data for scientists, marine spatial planners, and the fishing industry.

The most immediate benefit will be improved tsunami inundation modeling for the Oregon coast, according to Chris Goldfinger, director of the Active Tectonics and Seafloor Mapping Laboratory at Oregon State University, who led much of the field work.

“Understanding the nature of Oregon’s Territorial Sea is critical to sustaining sport and commercial fisheries, coastal tourism, the future of wave energy, and a range of other ocean-derived ecosystem services valued by Oregonians,” Goldfinger said. “The most immediate focus, though, is the threat posed by a major tsunami.

“Knowing what lies beneath the surface of coastal waters will allow much more accurate predictions of how a tsunami will propagate as it comes ashore,” he added. “We’ve also found and mapped a number of unknown reefs and other new features we’re just starting to investigate, now that the processing work is done.”

The mapping project was a collaborative effort of the National Oceanic and Atmospheric Administration, OSU’s College of Earth, Ocean, and Atmospheric Sciences, David Evans and Associations, and Fugro. It was funded by NOAA and the Oregon Department of State Lands.

Goldfinger said the applications for the data are numerous. Scientists will be better able to match near-shore biological studies with undersea terrain; planners will be able to make better decisions on siting marine reserves and wave energy test beds; and commercial and recreational fishermen will be able to locate reefs, rockpiles and sandy-bottomed areas with greater efficiency.

“Prior to this, most people used nautical charts,” Goldfinger said. “They would provide the depth of the water, the distance off shore, and in some cases, a bit about the ocean floor – whether it might be mud, rock or sand. Through this project, we’ve been able to map more than half of Oregon’s state waters in a much more comprehensive way.”

Oregon’s Territorial Sea extends three nautical miles from the coast and comprises about 950 square nautical miles. The researchers have created numerous different habitat maps covering 55 percent of those waters, which show distinction between fine, medium and coarse sands; display rocky outcrops; and have contour lines, not unlike a terrestrial topographic map.

Some of the mapping was done aboard the Pacific Storm, an OSU ship operated by the university’s Marine Mammal Institute. The project also utilized commercial fishing boats during their off-season.

More information about the project, as well as the maps and data, are available at: http://activetectonics.coas.oregonstate.edu/state_waters.htm

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Chris Goldfinger, 541-737-5214

Hatchery, OSU scientists link ocean acidification to larval oyster failure

CORVALLIS, Ore. – Researchers at Oregon State University have definitively linked an increase in ocean acidification to the collapse of oyster seed production at a commercial oyster hatchery in Oregon, where larval growth had declined to a level considered by the owners to be “non-economically viable.”

A study by the researchers found that elevated seawater carbon dioxide (CO2) levels, resulting in more corrosive ocean water, inhibited the larval oysters from developing their shells and growing at a pace that would make commercial production cost-effective. As atmospheric CO2 levels continue to rise, this may serve as the proverbial canary in the coal mine for other ocean acidification impacts on shellfish, the scientists say.

Results of the research have just been published in the journal, Limnology and Oceanography.

“This is one of the first times that we have been able to show how ocean acidification affects oyster larval development at a critical life stage,” said Burke Hales, an OSU chemical oceanographer and co-author on the study. “The predicted rise of atmospheric CO2 in the next two to three decades may push oyster larval growth past the break-even point in terms of production.”

The owners of Whiskey Creek Shellfish Hatchery at Oregon’s Netarts Bay began experiencing a decline in oyster seed production several years ago, and looked at potential causes including low oxygen and pathogenic bacteria. Alan Barton, who works at the hatchery and is an author on the journal article, was able to eliminate those potential causes and shifted his focus to acidification.

Barton sent samples to OSU and the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory for analysis. Their ensuing study clearly linked the production failures to the CO2 levels in the water in which the larval oysters are spawned and spend the first 24 hours of their lives, the critical time when they develop from fertilized eggs to swimming larvae, and build their initial shells.

“The early growth stage for oysters is particularly sensitive to the carbonate chemistry of the water,” said George Waldbusser, a benthic ecologist in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “As the water becomes more acidified, it affects the formation of calcium carbonate, the mineral of which the shell material consists. As the CO2 goes up, the mineral stability goes down, ultimately leading to reduced growth or mortality.”

Commercial oyster production on the West Coast of North America generates more than $100 million in gross sales annually, generating economic activity of some $273 million. The industry has depended since the 1970s on oyster hatcheries for a steady supply of the seed used by growers. From 2007 to 2010, major hatcheries supplying the seed for West Coast oyster growers suffered persistent production failures.

The wild stocks of non-hatchery oysters simultaneously showed low recruitment, putting additional strain on limited seed supply.

Hales said Netarts Bay, where the Whiskey Creek hatchery is located, experiences a wide range of chemistry fluctuations. The OSU researchers say hatchery operators may be able to adapt their operations to take advantage of periods when water quality is at its highest.

“In addition to the impact of seasonal upwelling, the water chemistry changes with the tidal cycle, and with the time of day,” Hales said. “Afternoon sunlight, for example, promotes photosynthesis in the bay and that production can absorb some of the carbon dioxide and lower the corrosiveness of the water.”

A previous study co-authored by Hales found the water that is being upwelled in the Pacific Ocean off the Oregon coast has been kept at depth away from the surface for about 50 years – meaning it was last exposed to the atmosphere a half-century ago, when carbon dioxide levels were much lower. “Since atmospheric CO2 levels have risen significantly in the past half-century, it means that the water that will be upwelled in the future will become increasingly be more corrosive,” Hales said.

The OSU researchers also found that larval oysters showed delayed response to the water chemistry, which may cast new light on other experiments looking at the impacts of acidification on shellfish. In their study, they found that larval oysters raised in water that was acidic, but non-lethal, had significantly less growth in later stages of their life.

“The takeaway message here is that the response to poor water quality isn’t always immediate,” said Waldbusser. “In some cases, it took until three weeks after fertilization for the impact from the acidic water to become apparent. Short-term experiments of just a few days may not detect the damage.”

The research has been funded by a grant from the National Science Foundation, and supported by NOAA and the Pacific Coast Shellfish Growers Association. Other authors on the journal article include Chris Langdon, of OSU’s Hatfield Marine Science Center, and Richard Feely, of NOAA’s Pacific Marine Environmental Laboratories.

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Burke Hales, 541-737-8121

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Whiskey Creek Hatchery Oyster larvae oyster spat

Welcome to spring – when snow isn’t as unusual as you might think…

CORVALLIS, Ore. – Many Oregonians woke up Wednesday morning to a blanket of snow, slushy roads and the realization that the arrival of spring doesn’t necessarily mean it’s time to get out the sunscreen.

But such weather isn’t all that unusual in western Oregon – especially during a La Niña winter, according to Kathie Dello, deputy director of the Oregon Climate Service at Oregon State University.

“This is the La Niña winter weather we’ve been waiting for,” Dello said. “It’s pretty typical – an active storm track, wet and cool. It’s a bit later than we’ve expected, but low-elevation snow in March isn’t unprecedented.

“La Niña is officially waning,” Dello added, “but she’s still got some fight in her.”

Late-season snow can be particularly problematic, Dello said, because it typically is wet and heavy, putting trees, branches and power lines in peril. Yet the cold, wet weather brings positive attributes along with the negative. Oregon’s snowpack is starting to recover and southern Oregon, in particularly, needed more snow in the mountains.

Despite the flooding in mid-January, the period from December to February was drier than normal. “It was the 10th driest winter on record in Oregon,” said Dello, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences.

Weather in the Pacific Northwest is in sharp contrast with much of the rest of the country, Dello noted, which is experiencing record high temperatures.

Just how unusual is spring snow? Dello says a quick check of the record books shows that March can indeed go out like a lion – and that April showers aren’t always rain. The year 1951 was particularly cold and wet, with up to eight days of measurable snowfall in much of western Oregon.

  • Corvallis: The latest measurable snowfall came in 2008, when 0.3 inches fell – believe it or not – on April 20. The heaviest March snowfall took place in 1960, when four inches fell on March 3.
  • Portland: The year 1951 was memorable in the Rose City, which had eight days with measurable snowfall in March of that year at the Portland Airport. The deepest March snowfall was on March 8, 1951, when 7.6 inches fell. Portland’s latest snowfall was on March 25, 1965, with 0.3 inches.
  • Eugene: There were five days of measurable snowfall in March of 1951 in Eugene, led by 4.9 inches on March 5. The latest snowfall was 0.5 inches on March 25, although snow records are spotty and snow was reported on April 20, 2008, but not recorded at the airport station.
  • Salem: There were eight days of measurable snowfall in 1951, but the highest March snowfall in Salem was on March 2, 1960, when 6.7 inches fell. The latest snowfall was 0.1 inches on April 8, 1972.

“Historic snow records can be a bit spotty,” Dello said, “and in some places, the overnight snowfall might be at near-record levels. There also is a lot of local variation. We’ve had volunteer observers with the CoCoRaHS program measure more than six inches of snow outside of Eugene today, and 4.5 inches in Monroe of southern Benton County.”

The program – known as the Community Collaborative Rain, Hail and Snow Network – helps experts enhance their snow observations by measuring and reporting local levels. More information on the program is available at: http://www.cocorahs.org/Maps/ViewMap.aspx?state=usa

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

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Kathie Dello, 541-737-8927

Scientists document first consumption of abundant life form, Archaea

CORVALLIS, Ore. – A team of scientists has documented for the first time that animals can and do consume Archaea – a type of single-celled microorganism thought to be among the most abundant life forms on Earth.

Archaea that consume the greenhouse gas methane were in turn eaten by worms living at deep-sea cold seeps off Costa Rica and the West Coast of the United States. Archaea perform many key ecosystem services including being involved with nitrogen cycling, and they are known to be the main mechanism by which marine methane is kept out of the atmosphere.

The finding of this new study adds a wrinkle to scientific understand of greenhouse gas cycles. Results of the study, which was funded by the National Science Foundation, have been published online in the International Society for Microbial Ecology Journal, a subsidiary of the journal Nature.

“This opens up a new avenue of research,” said Andrew Thurber, a post-doctoral researcher at Oregon State University and lead author on the study. “Archaea weren’t even discovered until 1977, and were thought to be rare and unimportant, but we are beginning to realize that they not only are abundant, but they have roles that have not fully been appreciated.”

Archaea are considered one of the three “domains of life” on Earth, along with bacteria and eukaryota (plants and animals). Despite their abundance, no member of the Archaea domain has been known to be part of a food web.

One of the basic questions scientists have asked is whether this life form could act as a food source for animals. To answer this, the researchers performed a laboratory study during which they fed two types of Archaea to the worms, as well as meals of bacteria, spinach or rice, and the worms thrived on all of the food sources, growing at the same rate.

“That showed us that Archaea can be a viable food source for at least some animals,” Thurber pointed out. 

Thurber and his colleagues initially were looking at biological life forms at a cold seep in the deep ocean off Costa Rica, when they opened up a rock and found worms living within the crevices. They found that the worms had been feeding on Archaea, which had, in turn, been consuming methane. They were able to trace the isotopic signature of the methane from the Archaea to the worms.

From what they learned from the Costa Rican study, the scientists also discovered that worms of the same family as those found in the rocks consume methane-munching Archaea at cold seeps off northern California and at Hydrate Ridge off the central Oregon coast, west of Newport. The researchers think the family of worms, the Dorvilleids, uses its teeth to scrape the Archaea off rocks.

The consumption of Archaea by grazers, a process coined “archivory” by Thurber in the article, is particularly interesting because the only way it could be documented was by tracing the isotopic biomarkers from the methane. When the researchers attempted to trace consumption of Archaea through lipid types and other mechanisms, they failed because the chemicals and proteins broke down within the worms.

“It could be that many other animals are consuming Archaea but we haven’t been able to detect it,” pointed out Thurber, who did much of the research as a doctoral candidate at the Scripps Institution of Oceanography.  “We still haven’t found the right technique to identify animals that eat Archaea that don’t rely on methane, but now we know to look.

“Hopefully, this will open up a lot of new research,” Thurber added, “and provide a greater understanding of how the world works.”

The deep ocean sequesters vast amounts of methane and researchers believe that Archaea consume a majority of it before it reaches the water column. The role of Archaea consumers now will have to be taken into effect, Thurber said.

“We’re not yet sure of the implications,” said Thurber, who is affiliated with OSU’s College of Earth, Ocean, and Atmospheric Sciences. “But Archaea are found in many different places, from estuaries to the deep sea, so it is possible that they fit into food webs beyond the cold seeps where we documented the process.”

Other authors on the paper include Lisa Levin of Scripps, and Victoria Orphan and Jeffrey Marlow of the California Institute of Technology.

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Andrew Thurber, 541-737-8251

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Archivory worm

Archaea-eating worm

 

Archaea rock

Rock where worms, Archaea were found

Antarctic salty soil sucks water out of atmosphere: Could it happen on Mars?

CORVALLIS, Ore. – The frigid McMurdo Dry Valleys in Antarctica are a cold, polar desert, yet the sandy soils there are frequently dotted with moist patches in the spring despite a lack of snowmelt and no possibility of rain.

A new study, led by an Oregon State University geologist, has found that that the salty soils in the region actually suck moisture out of the atmosphere, raising the possibility that such a process could take place on Mars or on other planets.

The study, which was supported by the National Science Foundation, has been published online this week in the journal Geophysical Research Letters, and will appear in a forthcoming printed edition.

Joseph Levy, a post-doctoral researcher in OSU’s College of Earth, Ocean, and Atmospheric Sciences, said it takes a combination of the right kinds of salts and sufficient humidity to make the process work. But those ingredients are present on Mars and, in fact, in many desert areas on Earth, he pointed out.

“The soils in the area have a fair amount of salt from sea spray and from ancient fjords that flooded the region,” said Levy, who earned his doctorate at Brown University. “Salts from snowflakes also settle into the valleys and can form areas of very salty soil. With the right kinds of salts, and enough humidity, those salty soils suck the water right out of the air.

“If you have sodium chloride, or table salt, you may need a day with 75 percent humidity to make it work,” he added. “But if you have calcium chloride, even on a frigid day, you only need a humidity level above 35 percent to trigger the response.”

Once a brine forms by sucking water vapor out of the air, Levy said, the brine will keep collecting water vapor until it equalizes with the atmosphere.

“It’s kind of like a siphon made from salt.”

Levy and his colleagues, from Portland State University and Ohio State University, found that the wet soils created by this phenomenon were 3-5 times more water-rich than surrounding soils – and they were also full of organic matter, including microbes, enhancing the potential for life on Mars. The elevated salt content also depresses the freezing temperature of the groundwater, which continues to draw moisture out of the air when other wet areas in the valleys begin to freeze in the winter.

Though Mars, in general, has lower humidity than most places on Earth, studies have shown that it is sufficient to reach the thresholds that Levy and his colleagues have documented. The salty soils also are present on the Red Planet, which makes the upcoming landing of the Mars Science Laboratory this summer even more tantalizing.

Levy said the science team discovered the process as part of “walking around geology” – a result of observing the mysterious patches of wet soil in Antarctica, and then exploring their causes. Through soil excavations and other studies, they eliminated the possibility of groundwater, snow melt, and glacial runoff. Then they began investigating the salty properties of the soil, and discovered that the McMurdo Dry Valleys weather stations had reported several days of high humidity earlier in the spring, leading them to their discovery of the vapor transfer.

“It seems kind of odd, but it really works,” Levy said. “Before one of our trips, I put a bowl of the dried, salty soil and a jar of water into a sealed Tupperware container and left it on my shelf. When I came back, the water had transferred from the jar to the salt and created brine.

“I knew it would work,” he added with a laugh, “but somehow it still surprised me that it did.”

Evidence of the salty nature of the McMurdo Dry Valleys is everywhere, Levy said. Salts are found in the soils, along seasonal streams, and even under glaciers. Don Juan Pond, the saltiest body of water on Earth, is found in Wright Valley, the valley adjacent to the wet patch study area.

“The conditions for creating this new water source into the permafrost are perfect,” Levy said, “but this isn’t the only place where this could or does happen. It takes an arid region to create the salty soils, and enough humidity to make the transference work, but the rest of it is just physics and chemistry.”

Other authors on the study include Andrew Fountain, Portland State University, and Kathy Welch and W. Berry Lyons, Ohio State University.

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Joe Levy, 541-737-4915

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McMurdo Dry Valleys
Polar desert sucks water from the atmosphere

Verena Tunnicliffe to deliver OSU “Vents” lecture on March 1

CORVALLIS, Ore. – Verena Tunnicliffe, a University of Victoria marine ecologist and explorer of deep-sea environments, will deliver a free public lecture at Oregon State University on Thursday, March 1, to commemorate OSU’s Hydrothermal Vents Discovery Day.

Tunnicliffe’s lecture is sponsored by the “Frontiers of Science” lecture series.

“Beyond the Mid-Ocean Ridge: Hydrothermalism and Vent Communities on Volcanic Arcs of the Western Pacific,” will provide a biologist’s viewpoint of hydrothermal eruptions in a different part of the ocean than on ridge crests, which are more widely known. Her talk begins at 4 p.m. in Gilfillan Auditorium on the OSU campus.

The lecture marks the 35th anniversary of the discovery of hydrothermal vents on a research cruise to the Galapagos, led by OSU scientist Jack Corliss. That discovery revealed an entire colony of marine creatures – many of which had never been seen before – and launched a new era of oceanographic exploration.

As more hydrothermal vents were documented beyond the ridge crest systems throughout the world oceans, scientists have discovered life-nurturing conditions in volcanic arcs and seamounts that have their own geophysical, chemical and biological features. Life at volcanoes ranges from shallow-water “smokers” to liquid carbon-dioxide vents and pools of molten sulfur.

These will be a focus of the presentation by Tunnicliffe, which is sponsored by OSU’s College of Earth, Ocean, and Atmospheric Sciences.

Tunnicliffe has worked closely with researchers at OSU’s Hatfield Marine Science Center, including Bill Chadwick and Susan Merle, on explorations of undersea volcanoes and associated hydrothermal vent colonies. She is a principal investigator with the Canadian Healthy Ocean Network, as well as the director of Ocean Network Canada’s VENUS (Victoria Experimental Network Under the Sea) cabled observatory.

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Bob Collier, 541-737-4367

"Patchiness” altering perceptions of ocean predators, prey

CORVALLIS, Ore. – Scientists and resource managers have always been interested in how animals in the ocean find their prey and the relative health of marine ecosystems is often judged by the abundance of food for the myriad species living there.

But new studies focusing on ocean “patchiness” suggest that it isn’t just the total amount of prey that is important to predators – it is the density of the food source, and ease of access to it.

Kelly Benoit-Bird, an Oregon State University oceanographer, outlined the importance of this new way of looking at ocean habitats during a keynote talk Wednesday (Feb. 22) at the 2012 Ocean Sciences meeting in Salt Lake City, Utah.

Sophisticated new technologies are helping scientists document how predators target prey, from zooplankton feasting on phytoplankton, to dolphins teaming up to devour micronekton, according to Benoit-Bird, who received a prestigious MacArthur Fellowship in 2010.

“We used to think that the size and abundance of prey was what mattered most,” said Benoit-Bird, a marine ecologist who studies relationships among marine species. “But patchiness is ubiquitous in marine systems and ultimately dictates the behavior of many animals and their relationships to the environment. We need to change our way of thinking about how we look at predator-prey relationships.”

Benoit-Bird pointed to a section of the Bering Sea, where her research with collaborators had estimated the abundance of krill. Closer examination through the use of acoustics, however, found that the distribution of krill was not at all uniform – and this may explain why two colonies of fur seals and seabirds were faring poorly, but a third was healthy.

“The amount of food near the third colony was not abundant,” she said, “but what was there was sufficiently dense – and at the right depth – that made it accessible to predators.”

The ability to use acoustics to track animal behavior underwater is opening new avenues to researchers.  During their study in the Bering Sea, Benoit-Bird and her colleagues discovered that they could also use sonar to plot the dives of thick-billed murres, which would plunge up to 200 meters below the surface in search of the krill.

Although the krill were spread throughout the water column, the murres ended up focusing on areas where the patches of krill were the densest.

“The murres are amazingly good at diving right down to the best patches,” Benoit-Bird pointed out. “We don’t know just how they are able to identify them, but 10 years ago, we wouldn’t have known that they had that ability. Now we can use high-frequency sound waves to look at krill, different frequencies to look at murres, and still others to look at squid, dolphins and other animals.

“And everywhere we’ve looked the same pattern occurs,” she added. “It is the distribution of food, not the biomass, which is important.”

An associate professor in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University, Benoit-Bird has received young investigator or early career awards from the Office of Naval Research, the White House and the American Geophysical Union. She also has received honors from the Acoustical Society of America, which has used her as a model scientist in publications aimed at middle school students.

Her work has taken her around the world, including Hawaii where she has used acoustics to study the sophisticated feeding behavior of spinner dolphins. Those studies, she says, helped lead to new revelations about the importance of patchiness.

Ocean physics in the region results in long, thin layers of phytoplankton that may stretch for miles, but are only a few inches thick and a few meters below the surface. Benoit-Bird and her colleagues discovered a layer of zooplankton – tiny animals that feed on the plankton – treading water a meter below to be near the food source. Next up in the food chain were micronekton, larger pelagic fish and crustaceans that would spend the day 600 to 1,000 meters beneath the surface, then come up to the continental shelf at night to target the zooplankton. And the spinner dolphins would emerge at night, where they could reach the depth of the micronekton.

“The phytoplankton were responding to ocean physics,” Benoit-Bird said, “but all of the others in the food chain were targeting their prey by focusing on the densest patches. We got to the point where we could predict with 70 percent accuracy where the dolphins would show up based just on the phytoplankton density – without even considering the zooplankton and micronekton distribution.”

Ocean “patchiness” is not a new concept, Benoit-Bird says, but may have been under-appreciated in importance.

“If you’re a murre that is diving a hundred meters below the surface to find food, you want to maximize the payoff for all of the energy you’re expending,” Benoit-Bird said. “Now we need more research to determine how different species are able to determine where the best patches are.”

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Kelly Benoit-Bird, 541-737-2063

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Dolphins circling prey
Dense patches of food draw ocean predators

OSU scientist receives prestigious Sloan Research Fellowship

CORVALLIS, Ore. – Angelicque “Angel” White, an oceanographer from Oregon State University, has received a 2012 Sloan Research Fellowship from the Alfred P. Sloan Foundation.

Fellowships were awarded to 126 top young researchers in the United States and Canada. Awarded annually since 1955, the fellowships are given to early-career scientists and scholars identified as rising stars and the next generation of scientific leaders.

“Today’s Sloan Research Fellows are tomorrow’s Nobel Prize winners, said Paul L. Joskow, president of the Alfred P. Sloan Foundation.

Sloan Fellowships historically have been awarded in seven fields, including chemistry, computer science, economics, mathematics, evolutionary and computational molecular biology, neuroscience, and physics. This year, the foundation expanded to include ocean sciences and awarded eight fellowships in that field, including the one to White.

White is an assistant professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences whose work focuses on ocean productivity and phytoplankton physiology. She is a member of the National Science Foundation-funded Center for Microbial Oceanography: Research and Education (C-MORE), and has been active in a collaborative project to monitor harmful algal blooms off the Oregon coast.

She also has studied the Pacific Ocean “garbage patch,” a huge collection of plastic trapped in a gyre off the West Coast, which she has described as problematic, but exaggerated in scale in many media reports.

Sloan Fellowships provide $50,000 over two years for equipment, technical assistance, professional travel, trainee support and other activities supporting the fellow’s research.

A list of the 2012 recipients is available at: www.sloan.org/fellowships/page/21

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Angel White, 541-737-6397

Scientists discover reason for Mt. Hood’s non-explosive nature

CORVALLIS, Ore. – For a half-million years, Mount Hood has towered over the landscape, but unlike some of its cousins in Oregon’s Cascade Mountains and many other volcanoes around the Pacific “Rim of Fire,” it doesn’t have a history of large, explosive eruptions.

Now a team of scientists has found out why.

In new research just published online in the Journal of Volcanology and Geothermal Research, lead author Alison Koleszar of Oregon State University and her colleagues describe how mixing of magma deep beneath Mount Hood appears to have prevented it from blowing its top over the millennia. Their research has been funded primarily by the National Science Foundation.

Volcanic eruptions are usually described as “high-explosivity” or “low-explosivity” events, said Koleszar, who is a post-doctoral researcher in OSU’s College of Earth, Ocean, and Atmospheric Sciences. Many volcanoes have experienced both. High-explosivity events are often referred to as Plinian eruptions, named after Pliny the Younger who described the eruption of Mount Vesuvius that destroyed the Roman city of Pompeii in AD 79. During these eruptions, large amounts of magma are ejected into the atmosphere at high velocity – such as Mount St. Helens in 1980 and Mount Pinatubo in 1992.

But studies of the rocks around Mount Hood show that the volcano has never experienced a Plinian eruption despite having similar chemical magma composition and gas contents as other volcanoes that have gone through these violent episodes.

The reason, Koleszar says, is that eruptions at Mount Hood appear to be preceded by episodes of intense mixing between magmas of different temperatures. Hot magma rises from deep below Mount Hood and mixes with the cooler magma that underlies the volcano. Heat from the deeper, hotter magma increases the temperature and lowers the viscosity of the magma that eventually erupts.

Instead of exploding, a la Mount St. Helens, magma at Mount Hood oozes out the top of the volcano and piles up to form a lava dome.

“If you take a straw and blow bubbles into a glass of milk, it will bubble up and allow the pressure to escape,” Koleszar said. “But if you blow bubbles into a thick milkshake you need more pressure and it essentially ‘erupts’ with more force as bits of milkshake get thrown into the air. Add a little heat to the milkshake, though, and it thins out and bubbles gently when you blow into it, more like the glass of milk.

"That what Mount Hood has been doing – heating things up enough to avoid a major explosion.”

What happens instead of an explosive eruption is more of a hiccup, according to Adam Kent, an OSU volcanologist who was Koleszar’s major professor when she earned her doctorate. The researchers analyzed three eruptive events on Mount Hood from the past 30,000 years, the last of which occurred about 220 years ago. These low-explosivity events resulted in the formation of lava domes near Mount Hood’s summit. Crater Rock, on the south side of the mountain, is a remnant of one of these lava domes.

“Instead of an explosion, it would be more like squeezing a tube of toothpaste,” said Kent, who also is an author on the study. “Lava piles up to form a dome; the dome eventually collapses under its own weight and forms a hot landslide that travels down the side of the volcano. In contrast, during a Plinian event such as the kind seen at other volcanoes, ash and rock are blown high into the air and distributed all over.”

Although Mount Hood lacks an explosive history, it doesn’t mean the 11,240-foot peak is completely docile. Collapses of the lava dome at Crater Rock about 1,500 years ago, and again 220 years ago, sent scalding landslides of hot lava blocks down the south side of the volcano, Kent pointed out.

“These types of events have dominated the eruptive activity at Mount Hood for the past 30,000 years,” Kent said. “The other danger is from lahars, which are major mudflows that stream down the side of the mountain at some 50 miles-an-hour, with the consistency of cement. They result when heat from the magma melts snow and mixes it with the volcanic ash and rock.

“Lahars probably accompany most eruptions of the volcano, and can even occur between eruptions after heavy rains or rapid snowmelt,” Kent added. “And they can go quite a ways – all the way to the Columbia River, for instance.”

Koleszar said few other volcanoes around the world act quite like Mt. Hood. It is, she said, a poster child for low-explosivity eruptions.

“Mount Hood is really cool because it is such a model for one extreme of volcano behavior,” Koleszar pointed out. “It may not have the colorful history of Mount Mazama or St. Helens, but it has its own niche among volcanoes – and now we better understand why it behaves the way it does.”

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