OREGON STATE UNIVERSITY

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Country’s largest estuary facing increasing acidification risk

CORVALLIS, Ore. – Chesapeake Bay, the largest estuary in the United States and one of the largest in the world, is facing new risks from a layer of highly acidified water some 10 to 15 meters below the surface, a new study has found.

This “pH minimum zone” is 10 times more acidic than the bay’s surface waters and may pose a risk to a variety of economically and ecologically important marine species, including oysters, crabs and fish, the researchers say. A decline in the number of calcium carbonate-shelled organisms – particularly oysters – may be hampering the bay’s ability to deal with the increase in acidity, they add.

Results of the study are being reported this week in Nature Communications.

“Oysters and other bivalves provide a built-in Tums effect that naturally helps the bay deal with corrosive water,” said George Waldbusser, an Oregon State University marine ecologist and co-author on the study. “They generate large amounts of calcium carbonate structures, which may be able to buffer the increasing amounts of carbon dioxide entering the bay.

“Overharvesting and disease have reduced the number of oysters, however, and we’re seeing the results.”

Lead author Wei-Jun Cai from the University of Delaware led the study, which found pH levels in this stratified layer of water to be about 7.4, nearly a unit lower than surface waters where the average pH is about 8.2. A combination of factors likely caused this corrosive zone, including hypoxia and generation of toxic hydrogen sulfide in the bottom waters mixing with other layers of the bay.

“This study shows for the first time that the oxidation of hydrogen sulfide and ammonia from the bottom waters could be a major contributor to lower pH in coastal oceans and may lead to more rapid acidification in coastal waters compared to the open ocean,” Cai said.

Previous studies, including work by Waldbusser, have shown that agricultural nutrients entering Chesapeake Bay have progressively depleted oxygen levels in the bottom waters – a process known as hypoxia – as well as acidifying the bay more quickly than offshore ocean waters. Animals need oxygen to live and without it, they die. Bacteria, however, can “breathe” without oxygen, often producing hydrogen sulfide, which further increases oxygen demand and also enhances acidification, Waldbusser said.

“Hypoxia in this case leads to an amplification of acidification,” he pointed out. “If more oysters were there, they would help pull the food out of the water, reduce oxygen demand, and sequester carbon from the system. Now the acidification is such that we have to be concerned that it will make it harder for some marine organisms to produce their calcium carbonate shells. We don’t yet know what those thresholds are all around.”

Oysters have been shown to be sensitive to changes in acidifications, particularly on the West Coast where corrosive waters severely affected the industry several years ago. Waldbusser and OSU colleague Burke Hales helped growers mitigate the issue by identifying times of the day when local acidification levels were lower so hatcheries could draw in more favorable waters to use in raising their oysters.

East Coast oysters are a different variety, Waldbusser said, and may actually be somewhat more resilient than the West Coast’s Pacific oysters. But scientific understanding of how much acidity they can withstand is limited.

“We know that in some areas of Chesapeake Bay where there has been high acidity, oysters have survived, but we don’t know if there are sub-populations that have more resilience, or what the threshold is for their ability to create shells.”

Waldbusser said individual oysters can filter upwards of 50 gallons of water each day. Researchers have estimated that prior to European settlement, Chesapeake Bay had so many oysters that they could filter the entire bay in three days. Today, it would take roughly 300 days because of fewer oysters and more nutrients in the water, he said.

“Dredging of the bay in the 1950s and 1960s removed a lot of oyster shells that formed a base for creating oyster reefs,” said Waldbusser, who began his research on oysters and acidification at the University of Maryland more than 10 years ago before coming to Oregon State.

“Since the 1980s, many of the restaurants on the East Coast participated in a program to recycle oyster shells into the bay to create more habitat, but it hasn’t been enough to replace what has been take out.”

Waldbusser is on the faculty of OSU’s College of Earth, Ocean, and Atmospheric Sciences.

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George Waldbusser, 541-737-8964, waldbuss@coas.oregonstate.edu

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Chesapeake Bay

Study: Methane from tundra, ocean floor didn’t spike during previous natural warming period

CORVALLIS, Ore. – Scientists concerned that global warming may release huge stores of methane from reservoirs beneath Arctic tundra and deposits of marine hydrates – a theory known as the “clathrate gun” hypothesis – have turned to geologic history to search for evidence of significant methane release during past warming events.

A new study published this week in the journal Nature suggests, however, that the last ice age transition to a warmer climate some 11,500 years ago did not include massive methane flux from marine sediments or the tundra. Instead, the likely source of rising levels of atmospheric methane was from tropical wetlands, authors of the new study say.

While this certainly is good news, the study also points at a larger role of humans in the recent methane rise, noted Edward Brook, an Oregon State University paleoclimatologist and co-author on the study

“Our findings show that natural geologic emissions of methane – for example, leakage from oil seeps or gas deposits in the ground – are much smaller than previously thought,” Brook said. “That means that a greater percentage of the methane in the atmosphere today is due to human activities, including oil drilling, and the extraction and transport of natural gas.”

The study suggests that human emissions of geologic methane may be as much as 25 percent higher than previous estimates. Although not as abundant as carbon dioxide, methane is a much more powerful greenhouse gas and therefore the rising levels are an important contributor to global warming.

“This means we have even more potential to fight global warming by curbing methane emissions from our fossil fuel use,” said Vasilii Petrenko, an associate professor of earth and environmental sciences at the University of Rochester, and lead author on the study.

Anthropogenic methane emissions are the second largest contributor to global warming after carbon dioxide, but there has been uncertainty as to the source of that methane and whether it has changed over time, Brook noted. The new study sheds light on the issue by analyzing levels of atmospheric methane from the last deglaciation in air bubbles that have been trapped in pristine ice cores from Antarctica’s Taylor Glacier.

The researchers were able to estimate the magnitude of methane emissions from roughly 11,500 years ago by measuring radioactive carbon isotopes in methane, (carbon-14, also known as 14C or radiocarbon), which decay fairly rapidly. Methane released from those marine hydrates and permafrost is old enough that any 14C originally present has now decayed away.

They found that amount of methane from ancient “14C-free sources” was very low – less than 10 percent of the total methane – during the entire range of sampling, from 11,800 to 11,300 years ago.

“A lot of people have painted the Arctic as a methane time bomb,” Brook said, “but this shows that it may be more stable than we thought. Past performance isn’t always a predictor of the future, but it is a good analog. We should be more concerned about anthropogenic sources of methane into the atmosphere, which continue to increase.”

The levels of 14C in the ice cores suggest that the increase in methane during the last deglaciation had another source – likely from tropical wetlands, said Christo Buizert, an Oregon State University researcher and co-author on the paper.

“Methane is not stored in the tropics for long periods of time, but produced every day by microbial activity in wetlands,” Buizert said. “We know from other studies that rainfall increased in the tropics during the last warming period, and that likely created more wetlands that produced the additional methane.”

Atmospheric methane has increased from 750 parts per billion in the year 1750 to more than 1,800 parts per billion today – mostly from anthropogenic sources, especially leakage from fossil fuel production, the creation of rice paddies, and cattle ranching, the researchers say.

“All of the natural gas that we mine is very old and leaking inevitably occurs during that process,” Brook said. “Natural gas is considered a cleaner energy source than coal, but it can be a significant problem depending on how much of the methane is leaking out.”

The key to documenting the source of atmospheric methane is the pristine ice cores of Taylor Glacier in Antarctica, where dry, windy conditions have allowed this ancient ice to be slowly brought to the surface. One reason scientists had yet to pin down the sources of methane during the last ice age is that the amount of 14C is so small, it takes enormous amounts of ice to get enough air to measure the isotope.

In fact, it takes some 2,000 pounds of ice, running a melting instrument over three days, to get enough air to produce one sample of measurable 14C. Drilling down in the center of the ice sheet to find that much ice from the end of the last ice age would be prohibitively costly and labor-intensive, but the unique conditions at Taylor Glacier – pushing that old ice toward the surface – made it possible.

Brook and Buizert are on the faculty of OSU’s College of Earth, Ocean, and Atmospheric Sciences

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Ed Brook, 541-737-8197, brooke@geo.oregonstate.edu;

Christo Buizert, 541-737-1572, buizertc.science.oregonstate.edu

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Field Office
Taylor Glacier in Antarctica

Are blue whales finding new "microphone channel" to communicate in?

NEWPORT, Ore. – For the past two decades, scientists have documented a gradual lowering of the frequency of blue whale calls and they haven’t been sure why – or even whether the phenomenon is intentional.

Other baleen whales in the North Pacific have been recorded in recent years generating vocalizations that are missing the “overtone” portions of their calls. Again, scientists are unsure why.

A new study published this week in Scientific Reports may shed some light on these mysteries. A group of acoustic researchers at Oregon State University’s Hatfield Marine Science Center recorded a blue whale call, then created a model to replicate that sound based on a series of controlled air bursts from the animal’s vocal cords.

In other words, they showed that whales can control the frequency of their calls by blowing air through their vocal cords at a faster or slower rate.

“Our study shows that blue whales in particular – and perhaps other baleen whales in general – may be making their harmonious sounds in a much different way than previously thought,” said Robert Dziak, an acoustics scientist with the National Oceanic and Atmospheric Administration and lead author on the study. “It was long thought that they generated their calls mostly by resonating sound in large chambers or cavities in their upper respiratory system.

“But this implies that the frequency of the whale’s calls are dictated by the size of the animal – the lower the frequency, the bigger the animal. We show that blue whales can make these low frequency sounds, and even change frequency in the middle of their call, by pulsing air through their vocal cords.”

“That also suggests that the change in the frequency might be cognitive. They are choosing to make it higher or lower in response to some sort of environmental stimulus.”

One theory is that as blue whale populations recover from commercial whaling, there are more of them and the lowering of frequency and other unusual characteristics of the calls are related to changes in population. It also is possible that an increase in ambient noise off the Pacific Coast plays a role, noted Joe Haxel, an Oregon State University acoustics specialist at Hatfield Marine Science Center.

“We conducted a year-long study of sound off the Oregon Coast and at times it can be really noisy out there,” Haxel said. “In addition to vibrant natural sounds – especially waves breaking on the beach – a few long-term studies have documented a substantial increase in ocean noise over several decades from expanding container shipping traffic.

“It may be possible the whales are modulating their vocalization frequency in response to an increase in human-generated noise. They are essentially trying to find a radio channel that has less static to communicate in.”

Dziak and his colleagues have created similar acoustic models to replicate the sounds of icebergs scraping across the seafloor as well as the explosions from undersea volcanic eruptions. To recreate the sound of a blue whale, they began using a clear call from a blue whale off Yaquina Head near Newport that they recorded using an undersea hydrophone that was part of a study to monitor the environmental impacts of wave energy.

They then developed acoustical models of the whale sound and incorporated anatomical respiratory system models of blue whales, the largest animals to have ever lived on Earth.

“We tried to envision a mechanism whereby whales could gradually lower the frequency of their calls through time, or produce calls with unusual harmonic structure, by only resonating sound in their upper respiratory chamber – and it was physically impossible,” said Dziak, who has a courtesy appointment in OSU’s College of Earth, Ocean, and Atmospheric Sciences.

“Only when we pulsed air through the process of opening and closing the vocal cords did we get a way to produce sounds that can change frequencies in mid-call as well as remove overtones. And this method produced models that matched the natural Yaquina Head blue whale call very, very closely.

“Lower-frequency sounds can be produced at lower intensity by the animal than high-frequency sounds and yet low-frequency sound still travels further,” Dziak pointed out. “Those factors may also play a role in the vocalization changes over the past two decades.”

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Bob Dziak, 541-867-0175, robert.p.dziak@noaa.gov;

Joe Haxel, 541-867-0282, joe.haxel@oregonstate.edu

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Tail of the whale
A blue whale off the California coast.

 

 

 

 

 

 

 


September workshop set to explore drilling project at Newberry Volcano

BEND, Ore. – An international group of geoscience experts will convene in Bend Sept. 10-14 to develop a proposal for drilling one of the hottest wells in the world at Newberry Volcano in central Oregon.

More than 40 scientists and engineers will meet at the Oregon State University-Cascades campus in Bend to explore options for the geothermal energy project, as well as funding potential. The workshop is sponsored by the International Continental Drilling Program, a non-profit organization that supports international science teams pursuing land-based drilling.

The event is being coordinated by the NEWGEN consortium, which was formed in 2015 by Pacific Northwest National Laboratory, AltaRock Energy, Oregon State University and Statoil to develop a research observatory on geothermal energy on Newberry Volcano.

The Newberry Geothermal Test Facility, located on the western flank of the caldera rim of Newberry Volcano, is one of the largest geothermal heat reservoirs in the western United States. Hot rock is relatively close to the surface at the site, making it easier to drill super-hot wells and carry out enhanced geothermal system research, according to Adam Schultz, an OSU geologist and geophysicist involved with the effort.

“There is enormous geothermal energy potential in the United States, with the greatest concentration of resources in the West,” Schultz said. “Our test site at Newberry Volcano represents one of the most promising geologic settings for geothermal power in the West, where super-hot rock could produce a high yield of stable, baseline electric power production that – unlike other renewable energy sources – doesn’t vary with sunlight, wind or wave conditions.

“Geothermal can serve as a like-for-like replacement for coal, oil, gas and nuclear power that can operate 24/7 and underpin our nation’s energy supply. By drilling deep beneath the west flank of the volcano, we can develop new technologies for green, carbon-free energy production.”

The site has been studied for 40 years and millions of dollars have been invested there by the U.S. Department of Energy and private geothermal developers, resulting in a ready-to-use facility with the necessary infrastructure, environmental permits, land commitments, and monitoring plans.

An idle geothermal exploration well drilled in 2008, which is 3,500 meters deep, has temperatures of 320 degrees Celsius (608 degrees Fahrenheit) at the bottom. Researchers are evaluating plans to deepen the well another 1,500 meters to reach temperatures above 450 degrees Celsius (842 degrees Fahrenheit).

Scientists and engineers with expertise in geothermal energy, high-temperature drilling, seismology and volcanology are expected to attend the workshop. They are from the U.S., Canada, Japan, Norway, Iceland, France and Italy.

More information on the project is available at http://www.newberrygeothermal.com.

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Adam Schultz, 541-737-9832, adam.schultz@oregonstate.edu

New assessment identifies global hotspots for water conflict

CORVALLIS, Ore. – More than 1,400 new dams or water diversion projects are planned or already under construction and many of them are on rivers flowing through multiple nations, fueling the potential for increased water conflict between some countries.

A new analysis commissioned by the United Nations uses a comprehensive combination of social, economic, political and environmental factors to identify areas around the world most at-risk for “hydro-political” strife. This river basins study was part of the U.N.’s Transboundary Waters Assessment Program.

Researchers from the United States, Spain and Chile took part in the analysis, which has been recommended by the U.N. Economic Commission for Europe as an indicator for the U.N.’s sustainable development goals for water cooperation.

Results of the study have just been published in the journal Global Environment Change. 

The analysis suggests that risks for conflict are projected to increase over the next 15 to 30 years in four hotspot regions – the Middle East, central Asia, the Ganges-Brahmaputra-Meghna basin, and the Orange and Limpopo basins in southern Africa.

Additionally, the Nile River in Africa, much of southern Asia, the Balkans in southeastern Europe, and upper South America are all areas where new dams are under construction and neighboring countries face increasing water demand, may lack workable treaties, or worse, haven’t even discussed the issue.

“If two countries have agreed on water flow and distribution when there’s a dam upstream, there usually is no conflict,” said Eric Sproles, an Oregon State University hydrologist and a co-author on the study. “Such is the case with the Columbia River basin between the United States and Canada, whose treaty is recognized as one of the most resilient and advanced agreements in the world. 

“Unfortunately, that isn’t the case with many other river systems, where a variety of factors come into play, including strong nationalism, political contentiousness, and drought or shifting climate conditions.”

The conflict over water isn’t restricted to human consumption, the researchers say. There is a global threat to biodiversity in many of the world’s river systems, and the risk of species extinction is moderate to very high in 70 percent of the area of transboundary river basins.

Asia has the highest number of dams proposed or under construction on transboundary basins of any continent with 807, followed by South America, 354; Europe, 148; Africa, 99; and North America, 8. But Africa has a higher level of hydro-political tension, the researchers say, with more exacerbating factors.

The Nile River, for example, is one of the more contentious areas of the globe. Ethiopia is constructing several dams on tributaries of the Nile in its uplands, which will divert water from countries downstream, including Egypt. Contributing to the tension is drought and a growing population more dependent on a water source that may be diminishing.

“When you look at a region, the first thing you try to identify is whether there is a treaty and, if so, is it one that works for all parties and is flexible enough to withstand change,” Sproles said. “It’s easy to plan for water if it is the same every year – sometimes even when it’s low. When conditions vary – and drought is a key factor – the tension tends to increase and conflict is more likely to occur.”

In addition to environmental variability and lack of treaties, other factors leading to conflict include political and economic instability, and armed conflict, the analysis shows.

Sproles said one reason the Columbia River Basin treaty between the U.S. and Canada has worked well is the relative stability of the water supply. In contrast, climate models suggest that the Orinoco River Basin in northern Brazil and the Amazon Basin in upper South America may face drier conditions, which could lead to more strife.

Sproles is a courtesy faculty member in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences, where he received his doctorate.

More information on the United Nations Transboundary Waters Assessment Program is available at: http://www.geftwap.org/.

A shorter version of the paper was published July 13 on the Sustainable Security website.

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Mark Floyd, 541-737-0788

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OSU inks largest research grant in its history to begin ship construction

CORVALLIS, Ore. – Oregon State University has just received a grant of $121.88 million from the National Science Foundation to spearhead the construction of a new class of research vessels for the United States Academic Research Fleet. It is the largest grant in the university’s history.

This grant will fund the construction of the first of three planned vessels approved by Congress for research in coastal regions of the continental United States and Alaska. When funding for the next two vessels is authorized, the total grant to OSU could increase to as much as $365 million. The first vessel is slated to be operated by OSU for research missions focusing on the U.S. West Coast. The NSF will begin the competitive selection of operating institutions for the second and third vessels later this year – likely to universities or consortia for operations on the U.S. East Coast and the Gulf of Mexico.

“Oregon State University is extremely proud to lead this effort to create the next generation of regional ocean-going research vessels funded by NSF,” said OSU President Edward J. Ray. “Our exceptional marine science programs are uniquely positioned to advance knowledge of the oceans and to seek solutions to the threats facing healthy coastal communities – and more broadly, global ecological well-being – through their teaching and research.”

OSU was selected by the National Science Foundation in 2013 to lead the initial design phase for the new vessels, and to develop and execute a competitive selection for a shipyard in the United States to do the construction. Gulf Island Shipyards, LLC, in Louisiana was chosen and will conduct the detailed design verification over the next year. Officials hope to have a keel-laying ceremony for the first vessel in the spring of 2018, with the ship delivered to OSU for a year of extensive testing in 2020.

This new class of modern well-equipped ships is essential to support research encompassing marine physical, chemical, biological and geologic processes in coastal waters, said Roberta Marinelli, dean of Oregon State’s College of Earth, Ocean, and Atmospheric Sciences.

“Rising sea levels, ocean acidification, low-oxygen waters or ‘hypoxia,’ declining fisheries, offshore energy, and the threat of catastrophic tsunamis are issues not only in the Pacific Northwest but around the world,” Marinelli said. “These new vessels will provide valuable scientific capacity for better understanding our changing oceans.”

The ships will be equipped to conduct detailed seafloor mapping, to reveal geologic structures important to understanding processes such as subduction zone earthquakes that may trigger tsunamis. The Pacific Northwest is considered a high-risk region because of the Cascadia Subduction Zone, which has produced about two dozen major earthquakes of magnitude 8.0 or greater over the past 10,000 years.

The new ships will also be equipped with advanced sensors that will be used to detect and characterize harmful algal blooms, changing ocean chemistry, and the interactions between the sea and atmosphere. The emerging fields of wave, tidal and wind energy will benefit from ship observations. Oregon State is the site of the Northwest National Marine Renewable Energy Center, which in December was awarded a grant of up to $35 million from the U.S. Department of Energy to create the world’s premier wave energy test facility in Newport.

Some characteristics of the new regional class research vessels (RCRVs), which were designed by The Glosten Associates, a naval architecture firm based in Seattle:

  • 193 feet long with a 41-foot beam;
  • Range of approximately 7,000 nautical miles;
  • Cruising speed is 11.5 knots with a maximum speed of 13 knots;
  • 16 berths for scientists and 13 for crew members;
  • Ability to stay out at sea for at least 21 days before returning to port;
  • High bandwidth satellite communications for streaming data and video to shore;

“This class of ships will enable researchers to work much more safely and efficiently at sea because of better handling and stability, more capacity for instrumentation and less noise,” said Clare Reimers, a professor in the College of Earth, Ocean, and Atmospheric Sciences and project co-leader. “The design also has numerous ‘green’ features, including an optimized hull form, waste heat recovery, LED lighting, and variable speed power generation.”

Oregon State is expected to begin operating the first of the new ships in the fall of 2021, after a year of testing and then official Academic-Fleet designation by the University-National Oceanographic Laboratory System (UNOLS), according to Demian Bailey, also a project co-leader for OSU.

“There will be a full year of testing because there are many interconnected systems to try out,” Bailey said. “Any new ship needs to have shakedown cruises, but we’ll have to test all of the scientific instrumentation as well, from the acoustic multibeam seafloor mapping system to its seawater and meteorological data collection, processing and transfer capabilities.

“These ships will be very forward-looking and are expected to support science operations for 40 years or longer. They will be the most advanced ships of their kind in the country.”

OSU previously operated the 184-foot R/V Wecoma from 1975 until 2012, when it was retired. The university then assumed operations of Wecoma’s sister ship, R/V Oceanus, from Woods Hole Oceanographic Institution; that ship will be retired when the new ship is ready.

The tentative timetable for the new ships:

  • Ship No. 1 keel laying – spring 2018;
  • Ship No. 1 transition to OSU for a year of testing – fall 2020;
  • Ship No. 1 should be fully tested, have UNOLS designation and be fully operational by fall 2021;
  • Ship No. 2 – Keel laying in winter of 2018, delivery in spring 2021, and UNOLS designation in late spring 2022;
  • Ship No. 3 – Keel laying in fall 2020, delivery in spring 2022, and UNOLS designation in spring 2023.

More information on the ships and the project is available at: http://ceoas.oregonstate.edu/ships/rcrv/.

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Mark Floyd, 541-737-0788

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Regional class research vessel

Regional class research vessel

Study finds Earth’s magnetic field ‘simpler than we thought’

CORVALLIS, Ore. – Scientists have identified patterns in the Earth’s magnetic field that evolve on the order of 1,000 years, providing new insight into how the field works and adding a measure of predictability to changes in the field not previously known.

The discovery also will allow researchers to study the planet’s past with finer resolution by using this geomagnetic “fingerprint” to compare sediment cores taken from the Atlantic and Pacific oceans.

Results of the research, which was supported by the National Science Foundation, were recently published in Earth and Planetary Science Letters.

The geomagnetic field is critical to life on Earth. Without it, charged particles from the sun (the “solar wind”) would blow away the atmosphere, scientists say. The field also aids in human navigation and animal migrations in ways scientists are only beginning to understand. Centuries of human observation, as well as the geologic record, show our field changes dramatically in its strength and structure over time.

Yet in spite of its importance, many questions remain unanswered about why and how these changes occur. The simplest form of magnetic field comes from a dipole: a pair of equally and oppositely charged poles, like a bar magnet.

“We’ve known for some time that the Earth is not a perfect dipole, and we can see these imperfections in the historical record,” said Maureen “Mo” Walczak, a post-doctoral researcher at Oregon State University and lead author on the study. “We are finding that non-dipolar structures are not evanescent, unpredictable things. They are very long-lived, recurring over 10,000 years – persistent in their location throughout the Holocene.

“This is something of a Holy Grail discovery,” she added, “though it is not perfect. It is an important first step in better understanding the magnetic field, and synchronizing sediment core data at a finer scale.”

Some 800,000 years ago, a magnetic compass’ needle would have pointed south because the Earth’s magnetic field was reversed. These reversals typically happen every several hundred thousand years.

While scientists are well aware of the pattern of reversals in the Earth’s magnetic field, a secondary pattern of geomagnetic “wobble” within periods of stable polarity, known as paleomagnetic secular variation, or PSV, may be a key to understanding why some geomagnetic changes occur. 

The Earth’s magnetic field does not align perfectly with the axis of rotation, which is why “true north” differs from “magnetic north,” the researchers say. In the Northern Hemisphere this disparity in the modern field is apparently driven by regions of high geomagnetic intensity that are centered beneath North America and Asia.

“What we have not known is whether this snapshot has any longer-term meaning – and what we have found out is that it does,” said Joseph Stoner, an Oregon State University paleomagnetic specialist and co-author on the study. 

When the magnetic field is stronger beneath North America, or in the “North American Mode,” it drives steep inclinations and high intensities in the North Pacific, and low intensities in Europe with westward declinations in the North Atlantic. This is more consistent with the historical record.

The alternate “European mode” is in some ways the opposite, with shallow inclination and low intensity in North Pacific, and eastward declinations in the North Atlantic and high intensities in Europe.

“As it turns out, the magnetic field is somewhat less complicated than we thought,” Stoner said. “It is a fairly simple oscillation that appears to result from geomagnetic intensity variations at just a few recurrent locations with large spatial impacts. We’re not yet sure what drives this variation, though it is likely a combination of factors including convection of the outer core that may be biased in configuration by the lowermost mantle.”

The researchers were able to identify the pattern by studying two high-resolution sediment cores from the Gulf of Alaska that allowed them to develop a 17,400-year reconstruction of the PSV in that region. They then compared those records with sediment cores from other sites in the Pacific Ocean to capture a magnetic fingerprint, which is based on the orientation of the magnetite in the sediment, which acts as a magnetic recorder of the past.

The common magnetic signal found in the cores now covers an area spanning from Alaska to Oregon, and over to Hawaii.

“Magnetic alignment of distant environmental reconstructions using reversals in the paleomagnetic record provides insights into the past on a scale of hundreds of thousands of years,” Walczak said. “Development of the coherent PSV stratigraphy will let us look at the record on a scale possibly as short as a few centuries, compare events between ocean basins, and really get down to the nitty-gritty of how climate anomalies are propagated around the planet on a scale relevant to human society.”

The magnetic field is generated within the Earth by a fluid outer core of iron, nickel and other metals that creates electric currents, which in turn produce magnetic fields. The magnetic field is strong enough to shield the Earth from solar winds and cosmic radiation. The fact that it changes is well known; the reasons why have remained a mystery.

Now this mystery may be a little closer to being solved.

Walczak and Stoner are in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. Other authors on the study are Alan Mix, also of OSU; John Jaeger, Gillian Rosen and James Channell of the University of Florida; David Heslop of Australian National University; and Chuang Xuan of the University of Southampton.

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Mark Floyd, 541-737-0788

Krill hotspot fuels incredible biodiversity in Antarctic region

CORVALLIS, Ore. – There are so many Antarctic krill in the Southern Ocean that the combined mass of these tiny aquatic organisms is more than that of the world’s 7.5 billion human inhabitants.

Scientists have long known about this important zooplankton species, but they haven’t been certain why particular regions or “hotspots” in the Southern Ocean are so productive. One such hotspot exists off Anvers Island – along the western Antarctic Peninsula – where high densities of Antarctic krill episodically concentrate near the shore close to a number of Adélie penguin breeding colonies. 

As it turns out, a perfect combination of tides and wind is responsible, according to scientists who just published a study on the krill in the journal Deep Sea Research. The research was funded by the National Science Foundation.

“This region off the western Antarctic Peninsula has been a known breeding area for Adélie penguins for thousands of years,” said Kim Bernard, a biological oceanographer at Oregon State University and lead author on the study. “We know it today as a krill hotspot and it probably has been for some time.

“But despite their abundance, there is growing concern about krill not only because of climate change, but because they are now being harvested for human food, nutritional supplements and aquaculture feed. Yet historically we’ve known little about what makes this particular area so productive for krill. So we set out to learn more about it.”

Bernard and a team of colleagues spent four consecutive summer seasons in the Antarctic mapping the patterns in distribution and biomass of Antarctic krill, also known as Euphausia superba. They also sought to identify the environmental conditions responsible for the hotspot. 

What they discovered is a near-perfect system in which krill aggregations situated over the Palm Deep Canyon – a region of nutrient-rich waters that produce a lot of food for the krill – are delivered close to shore by tidal currents and winds. When the winds are westerly and the tides are diurnal – one high tide and one low tide each day – the krill biomass close to shore is at its peak and krill aggregations are huge.

“It’s neat – we can predict exactly when humpback whales will be close to shore off Palmer Station just based on the tides,” Bernard said. “When there are diurnal tides, you’ll see krill from the surface to the ocean floor – they are everywhere. And when they are, the whales are there, too.

“This concentration and transport toward shore are particularly important for the penguins that breed there. The farther they have to go to forage, the less their chicks have to eat and chick weight is a huge factor in their survival. A difference of a few hundred grams in chick weight is the difference between life and death.”

When the tides shift to semi-diurnal – two high and two low tides daily – currents move the krill away from shore and their predators follow. Likewise, a shift to southerly winds keeps the krill farther from shore and more spread out.

Antarctic krill can live five to seven years, and grow to a length of a little more than two inches. They don’t reach sexual maturity for two years, and when they reproduce, they must release their eggs in water roughly 1,000 meters (or about 3,200 feet) deep. That’s because they need a certain period of time to develop as they drift to the ocean floor, and another period of time to go through different life stages as they re-ascend to the surface.

Studies have shown that sea ice may be critical to their survival, but scientists are not exactly sure why, Bernard said.

“We see very strong correlations between krill biomass and sea ice,” she noted. “When the sea ice is low, the krill populations crash the next summer. It could be a change in algae or other food for them, or it could be that sea ice provides shelter from predators, or affects the currents in some way. We just don’t yet know.

“It would be nice to find out, because sea ice abundance may vary greatly in the future.”

Bernard is on the faculty of OSU’s College of Earth, Ocean, and Atmospheric Sciences.

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Penguins rely on close-to-shore krill

Analyzing magma temperatures may help get closer to forecasting volcanic eruptions

CORVALLIS, Ore. – Although volcanic eruptions are often quite hazardous, scientists have been unable to pinpoint the processes leading up to major eruptions – and one important limitation has been a lack of knowledge about the temperature history of the magma.

A new study analyzed crystals of the mineral zircon – zirconium silicate – in magma from an eruption in the Taupo Volcanic Zone in New Zealand about 700 years ago to determine the magma’s history. The analysis shows the magma went through a comparatively “cool” period for thousands of years before heating up. Once magma temperatures reached 750 degrees Celsius, it was a short amount of time – decades or less – before an eruption occurred.

This pattern of long-term crystal storage in near-solid magma, punctuated by rapid heating, is applicable to many other volcanoes around the world, the researchers say, and may begin to help scientists recognize when a volcano is heading toward an eruptive phase.

Results of the research, which was supported by the National Science Foundation, are being reported this week in Science.

“Mobility in magma is a function of temperature and most of the time when it’s sitting there in the Earth’s crust under the volcano it’s cool,” said Adam Kent, an Oregon State University geologist and co-author on the study. “Of course, cool is a relative description since it’s still some 650 degrees (Celsius). I wouldn’t put my finger on it.

“But to erupt onto the Earth’s surface magma needs to heat up so it can be runny enough to be squeezed along cracks in the Earth and pushed up to the surface. At lower temperatures, the magma is too crystal-rich and viscous to move. It’s like trying to spread cold peanut butter onto a piece of bread. It takes higher temperatures to get things moving – and then our data show it’s only a period of years or decades before it erupts.”

Kent said the Taupo magma system has similarities to many volcanoes around the world, including the Cascade Range in the Pacific Northwest of the United States. A past study by Kent and his colleagues using a different approach found that Mount Hood in Oregon also spent most of its history in a cold, rigid state before moving rapidly into an eruptive phase.

This new study adds more certainty to the method and provides a new tool to apply this work to other volcanoes, the researchers say.

The key to honing in on these long-term geologic processes is understanding the volcanoes’ thermal or temperature history, according to the researchers. Past studies began making inroads into understanding the history of magma temperatures, but they relied on trying to reconcile data from a sample containing many thousands of individual crystals.

Using zircon crystals, which can be dated through analyzing the decay of uranium and thorium, adds more resolution, or precision, to the process. The crystals are like a “black box” flight recorder for studying volcanic eruptions, according to Kari Cooper of the University of California, Davis, corresponding author on the study.

“Instead of trying to piece together what happened from the wreckage,” Cooper said, “the crystals can tell us what was going on while they were below the surface, including the runup to an eruption.”

Zircon crystals occur in magma from many volcanoes and the new technique will have wide applications to volcanoes along the ring of fire – the belt of volcanoes that surround the Pacific Ocean – and elsewhere.

“It removes some uncertainty and gives us a great new tool to go back and look at other volcanoes,” Kent said.

The finding also suggests that if many volcanoes store their magma in this relatively cold state, recognizing volcanoes where warm and mobile magma is present may help researchers find volcanoes in the early throes of producing future eruptions. The technology to monitor volcanoes using seismic waves and other remote techniques is improving all the time, the researchers said.

The Science study was led by Allison Rubin and Cooper of the University of California at Davis. Other researchers included Christy Till and Maitrayee Bose of Arizona State University; Fidel Costa, Nanyang Technological University of Singapore; Darren Gravley and Jim Cole of the University of Canterbury in New Zealand; and Chad Deering, Michigan Technological University.

Kent is on the faculty of the College of Earth, Ocean, and Atmospheric Sciences at Oregon State.

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Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe

CORVALLIS, Ore. – Sediment that eroded from the Himalayas and Tibetan plateau over millions of years was transported thousands of kilometers by rivers and in the Indian Ocean – and became sufficiently thick over time to generate temperatures warm enough to strengthen the sediment and increase the severity of the catastrophic 2004 Sumatra earthquake.

The magnitude 9.2 earthquake on Dec. 26, 2004, generated a massive tsunami that devastated coastal regions of the Indian Ocean. The earthquake and tsunami together killed more than 250,000 people making it one of the deadliest natural disasters in history.

An international team of scientists that outlined the process of sediment warming says the same mechanism could be in place in the Cascadia Subduction Zone off the Pacific Northwest coast of North America, as well as off Iran, Pakistan and in the Caribbean.

Results of the research, which was conducted as part of the International Ocean Discovery Program, are being published this week in the journal Science.

“The 2004 Indian Ocean tsunami was triggered by an unusually strong earthquake with an extensive rupture area,” said expedition co-leader Lisa McNeill, an Oregon State University graduate now at the University of Southampton. “We wanted to find out what caused such a large earthquake and tsunami, and what it might mean for other regions with similar geological properties.”

The research team sampled for the first time sediment and rocks from the tectonic plate that feeds the Sumatra subduction zone. From the research vessel JOIDES Resolution, the team drilled down 1.5 kilometers below the seabed, measured different properties of the sediments, and ran simulations to calculate how the sediment and rock behaves as it piles up and travels eastward 250 kilometers toward the subduction zone.

“We discovered that in some areas where the sediments are especially thick, dehydration of the sediments occurred before they were subducted,” noted Marta Torres, an Oregon State University geochemist and co-author on the study. “Previous earthquake models assumed that dehydration occurred after the material was subducted, but we had suspected that it might be happening earlier in some margins.

“The earlier dehydration creates stronger, more rigid material prior to subduction, resulting in a very large fault area that is prone to rupture and can lead to a bigger and more dangerous earthquake.”

Torres explained that when the scientists examined the sediments, they found water between the sediment grains that was less salty than seawater only within a zone where the plate boundary fault develops, some 1.2 to 1.4 kilometers below the seafloor.

“This along with some other chemical changes are clear signals that it was an increase in temperature from the thick accumulation of sediment that was dehydrating the minerals,” Torres said.

Lead author Andre Hüpers of the University of Bremen in Germany said that the discovery will generate new interest in other subduction zone sites that also have thick, hot sediment and rock, especially those areas where the hazard potential is unknown.

The Cascadia Subduction Zone is one of the most widely studied sites in the world and experts say it may have experienced as many as two dozen major earthquakes over the past 10,000 years.

The sediment at the Cascadia deformation front is between 2.5 and 4.0 kilometers thick, which is somewhat less than the 4-5 kilometer thickness of the Sumatra region. However, because the subducting plate at Cascadia is younger when the plate arrives at the subduction zone, the estimated temperatures at the fault surface are about the same in both regions.

Torres is a professor in Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences.

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Marta Torres, 541-737-2902, mtorres@coas.oregonstate.edu

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Sediment cores

Sediment cores