Geobiologists propose that the earliest complex organisms fed by absorbing ocean buffet

Research at Virginia Tech has shown that the oldest complex life forms — living in nutrient-rich oceans more than 540 million years ago – likely fed by osmosis.

The researchers studied two groups of modular Ediacara organisms, the fern-shaped rangeomorphs and the air mattress-shaped erniettomorphs. These macroscopic organisms, typically several inches in size, absorbed nutrients through their outer membrane, much like modern microscopic bacteria, according to the cover story of the Aug. 25, 2009 issue of the Proceedings of the National Academy of Sciences (PNAS), “Osmotrophy in modular Edicara organisms,” by Marc Laflamme, Shuhai Xiao, and Michal Kowalewski. Laflamme, now a Postdoctoral Fellow in the Department of Geology and Geophysics at Yale University, did the research as a postdoc in Xiao’s lab at Virginia Tech. Xiao and Kowalewski are professors of geobiology in the College of Science at Virginia Tech.

The rangeomorphs had a repeatedly branching system like fern leaves and the erniettomorphs had a folded surface like an inflated air mattress to make tubular modules. “These organisms are unlike any life forms since and so are poorly understood,” said Laflamme.

Their feeding strategy has been a topic of controversy, with theories ranging from parasitism to symbiosis to photosynthesis. “Some hypotheses can be ruled out because the organisms lack feeding structures, such as tentacles or mouths, and because many of them lived in the deep ocean where there was no sunlight for photosynthesis” said Xiao.

The researchers decided to simulate various morphological changes in the overall construction of the organisms to test whether it would have been possible for them to attain surface area to volume ratios on the same order as modern bacteria that feed by osmosis. Theoretical models were constructed to explore the effects of length, width, thickness, number of modules, and presence of internal vacuoles, on the surface area of the Precambrian fossils. “Modeling efforts suggest that internal vacuoles – that is, voids filled with fluids or other biologically inert materials – are a particularly effective way of increasing surface-to-volume ratio of complex, macroscopic organisms,” said Kowalewski.

They discovered that the two groups (the repeatedly branching rangeomorphs and the air-mattress like erniettomorphs) grew and constructed their bodies in different ways; however both groups attempted to maximize their surface-area to volume ratios in their own way. “The increase in size was clearly accomplished primarily by addition of modules for the erniettomorphs and repetitive branching and inflation of modules for the rangemorphs,” Laflamme said. “The repeated branching system in rangeomorphs was essential to allow for a high surface-area to volume ratio necessary for proper osmosis-based feeding.”

Today, only microscopic bacteria find it efficient to us only osmosis to feed, although some animals, such as sponges and corals, use osmosis as a supplementary food source. But in the Ediacaran period, 635 to 541 million years ago, with nutrient-rich oceans, “a diffusion-based feeding strategy was more feasible,” Laflamme said.

“We believe the Ediacarans were feeding on dissolved organic carbon, which can come in many forms,” he said. “It represents the organic material originating from plants, fungi, animals — you name it, which has dissolved into fats and proteins during natural organic decay. There is a growing body of evidence that in Ediacaran times, due mainly to the absence of animals with true guts capable of packaging organic matter into fecal pellets, there was a much greater pool of dissolved organic nutrients, especially in deeper waters. Without fecal pellets, organic substances would have remained in suspension and decomposed into fats and proteins capable of dissolution into marine waters,” he said. “We believe these compounds were then absorbed via osmosis through Ediacaran “skin” due to the high surface-area to volume ratios.”

The PNAS article concludes that today “giant sulfur bacteria, such as Thiomargarita, thrive along the coastal area of Namibia, where constant upwelling allows for greater access to (dissolved organic carbon) and nutrients. Such nutrient-rich areas may be modern-day analogs to Ediacaran deep oceans … suggesting that it may be more than coincidental that the earliest rangeomorphs occurred in (dissolved organic carbon)-rich deep waters.”

Research institutes from Bremen install new Arctic deep-sea observatory

The ROV MARUM-QUEST can operate in depths down to 4000 meters below sea level. -  Photo: Dirk Olonscheck, Alfred Wegener Institute
The ROV MARUM-QUEST can operate in depths down to 4000 meters below sea level. – Photo: Dirk Olonscheck, Alfred Wegener Institute

Three research institutes from the German federal state Bremen among others have set up an observation ward for the long-term observation of a mud volcano in the Norwegian deep sea. This took place during RV Polarstern’s 24th Arctic expedition from July 10th until August 3rd. The endeavours are part of the project ESONET (European Seas Observatory NETwork), funded by the European Union. Its purposes are to provide information about the dynamics of gas eruptions in the next years and to show the consequences of these eruptions, for example on the biological communities on the seafloor.

Another investigation area was the deep sea ecosystem west of Spitsbergen, the so-called “Hausgarten” of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. 50 researchers from seven nations participated in the research activities on board of Polarstern.

The Fram Strait between eastern Greenland and Spitsbergen is the only deep sea connection between the North Atlantic and the central Arctic Ocean. The Hausgarten is situated here and the Alfred Wegener Institute is conducting long-term observations at this observatory since 1999. The observatory consists of 16 separate stations from 1.000 to 5.500 m depth. The researchers are able to discern considerable changes after a decade of systematic research. The water temperature in 2.500 m depth has increased by a tenth degree Celsius, for example. There is first evidence that the oxygen saturation has decreased at the boundary layer between seafloor and water and that the composition of the animal community has changed quicker than expected. “Whether we really observe consequences of rapid change in the Arctic in several thousand metres of water depth, or if we are witnesses to natural changes taking place over several decades will be seen after the analysis of our data and further research”, says Dr. Michael Klages, biologist at the Alfred Wegener Institute and scientific head of the expedition.

The research schedule at the AWI Hausgarten further contributes to other projects funded by the European Union: for example, work in shallower sea areas has been carried out in coordination with Norwegian Institutes in the framework of a project financed by the company StatoilHydro.

The construction of the long-term observatory LOOME (Long Term Observation of Mud Volcano Eruptions) was another focus of the expedition. The target of the observatory is to better understand the Hakon Mosby mud volcano situated at the Norwegian continental shelf in regard to the processes happening inside. The mud volcano has a diameter of about 1.5 km and it lies in 1.250 m water depth in the southwestern Barent Sea. Mud, gases and water are pressed from the centre of the active mud volcano from a depth of about three kilometres to the surface of the seafloor. The efflux decreases in the direction of the outer areas of this structure. This is the spot where methane gas hydrates can be found on the floor which help to stabilize this zone

Earlier research conducted by the Alfred Wegener Institute, the Max Planck Institute for Marine Microbiology and the French Institute IFREMER show that the efflux controls the distribution of biological communities and the stability of the gas hydrates as well as their release. With the construction of the long-term observatory it is possible to examine the mud volcano in regard to sudden gas eruptions and possible effects on the gas hydrate system, the composition of the soil and the organisms living at the fringe of the mud volcano. “The distribution of the long-term observatory is an important milestone of the project ESONET”, explains Dr. Dirk DeBeer, coordinator of the project from the Max Planck Institute for Marine Microbiology in Bremen. “It was possible to install the complicated construction of the observatory as planned with the help of all partners from Germany, France and Norway involved in the project. It shows again that good collaboration of the involved institutes is an important component of European marine research”, DeBeer continues.

The availability of a remote-controlled submarine vehicle, a so-called ROV (Remotely Operated Vehicle), was essential for the scientific work in the investigation area. The deep sea robot QUEST from the Center for Marine Environmental Research (Marum) of the University Bremen was therefore on board of Polarstern for the second time after 2007. “This journey posed the highest scientific-technical demands on the ROV and my team”, explains Dr. Volker Ratmeyer, head of QUEST at Marum. “I think that we were able to show with our expedition that it is possible to work on tasks of this difficulty in Germany as well, like the installation of a deep sea observatory or the retrieval of heavy equipment”, Ratmeyer continues. Klages adds:”It is impressive to see the level of competence that has grown together during the last years between Bremerhaven and Bremen. It is also impressive to see what we are able to achieve in deep sea research if we bring our excellent infrastructures jointly into such projects.”

‘Hydropalooza’ provides deeper understanding of Alaska’s Kachemak Bay

NOAA ships and scientists have returned to Alaska’s Kachemak Bay to kick off year two of Hydropalooza – a NOAA-led project to develop the most detailed seafloor and coastline maps ever generated of the area.

Kachemak Bay, one of south central Alaska’s most productive and ecologically diverse estuaries, supports maritime commerce, ferry transportation, fishing, and recreational boating from the nearby harbors of Homer and Seldovia. Up-to-date NOAA nautical charts, as well as sea bottom, water level, and shoreline information, are needed to ensure safe navigation, manage coastal resources, and support local planning.

“The mapping data that NOAA collects will be used by state and local officials to make better informed decisions related to the coast, its habitats and its people,” said James Hornaday, mayor of Homer. “I welcome our NOAA friends back to Kachemak Bay.”

Crews on board NOAA ships Fairweather and Rainier will conduct hydrographic surveys of the seafloor, measuring depths and identifying obstructions. When the ships complete data collection in early September, they will have surveyed more than 350 square nautical miles-an area nearly twice the size of Chicago.

“This is one of our largest survey efforts of the year,” said Capt. Steven Barnum, director of NOAA’s Office of Coast Survey and U.S. national hydrographer. “The data we collect will contribute to navigation safety in the state and also be used to keep the coast healthy and productive.”

The vessels will also install new tide stations and high-precision global positioning system (GPS) base stations, which will record water levels and location information in real time. With Kachemak Bay’s 28-foot tidal range from low to high tide – the fourth largest in North America – these data are needed to ensure the best quality surveys are conducted.

Scientists from the NOAA Kasitsna Bay Laboratory, Kachemak Bay National Estuarine Research Reserve, Alaska Department of Fish and Game, University of Alaska Fairbanks and other NOAA offices are collaborating on how to use Hydropalooza mapping data to improve assessment and management of coastal resources. NOAA and Alaska Department of Environmental Conservation scientists are also conducting sediment sampling to assess pollutant levels and biodiversity on the seafloor.

NOAA and the University of Alaska-Fairbanks will also use this detailed mapping data to provide an opportunity for college students to train in how to better sustain marine ecosystems in the Arctic and subarctic.

The collection of shoreline and seafloor mapping data for a range of uses is the primary objective behind the federal multi-agency Integrated Ocean and Coastal Mapping initiative. The program allows NOAA and its partners to maximize the benefits of the data collected.

“Our data are used by countless federal, state, and local stakeholders,” said Captain Roger Parsons, NOAA Corps (ret.), IOCM director. “Coastline and seafloor data, once collected solely for updating NOAA’s national suite of nautical charts, is now used for marine spatial planning efforts, ocean circulation monitoring, and assessing the impacts of climate change, among other uses.”

Ocean-drilling expedition cites new evidence related to origin and evolution of seismogenic faults

Dr. Michael Strasser (center, MARUM at Bremen University, Germany) and science party observe core sample recovered from Nankai Trough at the laboratory on the Chikyu during IODP Expedition 316 in 2007-2008. -  Copyright: JAMSTEC/IODP
Dr. Michael Strasser (center, MARUM at Bremen University, Germany) and science party observe core sample recovered from Nankai Trough at the laboratory on the Chikyu during IODP Expedition 316 in 2007-2008. – Copyright: JAMSTEC/IODP

New research about what triggers earthquakes, authored by Michael Strasser of Bremen University, Germany, with colleagues from the USA, Japan, China, France, and Germany, will appear in the Aug. 16 2009 issue of Nature Geoscience (online version). The research article, titled “Origin and evolution of a splay-fault in the Nankai accretionary wedge” is drawn from the scientists’ participation in the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), a long-term scientific ocean-drilling project conducted by the Integrated Ocean Drilling Program (IODP). Since September 2007, rotating teams of scientists have spent months aboard Japan’s drilling vessel, CHIKYU, investigating the Nankai Trough, a seismogenic zone located beneath the ocean off the southwest coast of Japan. Drilling operations, managed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) through its Center for Deep Earth Exploration, have resulted in a collection of cored samples from the sea floor, which have provided scientists with deeper insights into the geologic past of the area.

Discussion in the above-noted article focuses on the Nankai Trough, in which the Philippine Sea plate slips below the Eurasian Plate with a velocity of 4 cm per year. This area is one of the most active earthquake zones on the planet. While being subducted, sediments are scraped off the oceanic plate and added to the overriding continental plate. Due to the movement of the plates these so-called accretionary wedges are exposed to enormous stress that form large faults. The landward wedge in the Nankai Trough is completely intersected by such a prominent fault which extends laterally over more than 120 km. Scientists refer to this structure as “the megasplay.” Movements along such megasplay faults during large magnitude earthquakes generated at depth may rupture the ocean floor and generate tsunamis.

“Our knowledge of megasplay faults up till now has been based on seismic or modelling experiments accomplished over the last twenty years,” says Michael Strasser of Post-Doc Fellow of the Center for Marine Environmental Sciences (MARUM) at University of Bremen. “For the first time, with cored samples brought onto the CHIKYU, it has become possible to reconstruct the geological history of a fault in great detail.” With his associates, Dr. Strasser found that the fault in the Nankai Trough originated about two million years ago. From the information recorded in the cores, the research team can draw conclusions on the mechanics of the accretionary wedge. They also can infer in which geological time periods the fault was most active.

“Our most significant conclusion is that splay fault activity varies through time,” Dr. Strasser states. According to Strasser, after an initial period of high activity, the movement along the fault slowed down. Since about 1.55 million years ago, this fault has been reactivated, favoring ongoing megasplay slip along it.

“It is absolutely fascinating to be part of NanTroSEIZE,” says Strasser, noting that the expedition series aims to sample and monitor activity at the point where earthquakes originate. “NanTroSEIZE is something completely new and innovative in scientific drilling,” Strasser explains. “Ultimately, we hope to detect signals occurring just before an earthquake to get a better understanding of the processes leading to earthquakes and tsunamis.”

The Nankai Trough is particularly suited for this experiment because historical records of earthquakes and tsunamis in this area date back into the seventh century. Additionally, the area where earthquakes are generated, the so-called seismogenic zone, is located at a relatively shallow depth of about six kilometers below the seafloor.

In 2007 and 2008, during the first stage of NanTroSEIZE, the deep sea drilling vessel CHIKYU carried out three expeditions. This drilling project consists of four stages in all, and ultimately focuses on “ultra-deep” drilling that can reach the seismogenic zone, where great earthquakes have occurred repeatedly.

During upcoming expeditions, the Nankai Trough boreholes will be equipped with instruments to establish an ocean observatory network. Currently, scientists are making preparations to install monitoring devices for continous measurements of the Nankai Trough. Prof. Gaku Kimura of University of Tokyo, who led an earlier NanTroSEIZE expedition 316 as Co-Chief Scientist says, “Not only do we have new insights about historic fault activities in Nankai Trough, but the data strongly suggests that the megasplay fault may be a key factor in the occurrence of large earthquakes in the future.” He adds, “Greater understanding about the processes of earthquake and tsunami generation in the active subduction zone will be a great contribution to society.”

NOAA and Oregon State University map Oregon’s seafloor

Surveyors and scientists from NOAA’s Office of Coast Survey and Oregon State University over the next two years will create the most detailed maps ever generated of the seafloor along Oregon’s coast. Using the latest technologies, they will measure water depth, search for navigational hazards, and record the natural features of coastal seabeds and fragile aquatic life. The images will help researchers and coastal managers protect coastal communities and marine habitat.

“These projects help Oregon prepare for future challenges,” said Oregon Gov. Ted Kulongoski. “With the data collected from these surveys, we can model tsunamis, identify marine habitats, select alternative energy sites, identify geological hazards, and enhance safe and efficient marine transportation.”

NOAA awarded $5 million to private contractors to assist in the joint effort. The State of Oregon provided $1.3 million in funding to OSU. NOAA will use the data from the surveys to update nautical charts that currently contain depth information acquired before 1939.

“Officials need the best possible information to manage ocean and coastal resources,” said John H. Dunnigan, assistant administrator for NOAA’s National Ocean Service. “Updated nautical charts will also make ocean shipping and recreational boating along Oregon’s coasts much safer.”

“Along with the governors of California and Washington, I set a goal of mapping our three states’ ocean areas by the year 2020,” Kulongoski added. “Thanks to the strong partnership between NOAA, academia, private industry, fishermen, state legislators, and multiple state and federal agencies, Oregon is on track to reach that goal.”

With a resolution of a half-meter, the maps will cover about 34 percent of the state waters and 75 percent of its rocky reefs, recording every bump, depression, reef and boulder on the seafloor from a depth of 10 meters out to three miles, the boundary of Oregon’s territorial sea.

Chris Goldfinger, an associate professor of oceanic and atmospheric sciences at OSU, says the university’s work will begin immediately and will focus initially on sites important for tsunami modeling, wave energy, and marine reserves. Some maps of Oregon’s territorial sea and seabed habitats, showing water depths and topography, are already online.

Goldfinger previously led an effort to create a map of Oregon’s territorial sea and seabed habitats, which show water depths and topography and can be overlaid with information about buoys, seabirds, marine life, and kelp beds. The map is available online at the site listed below. New products from this project will be distributed through the same site.

Oregon state legislators from districts along the coast, led by state Rep. Deborah Boone, spearheaded the OSU project. The Oregon Department of State Lands and other state agencies supported the effort which also meets goals set in the West Coast Governors’ Agreement on Ocean Health.

The OSU College of Oceanic and Atmospheric Sciences 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.

Heavier rainstorms ahead

Heavier rainstorms lie in our future. That’s the clear conclusion of a new MIT and Caltech study on the impact that global climate change will have on precipitation patterns.

But the increase in extreme downpours is not uniformly spread around the world, the analysis shows. While the pattern is clear and consistent outside of the tropics, climate models give conflicting results within the tropics and more research will be needed to determine the likely outcomes in tropical regions.

Overall, previous studies have shown that average annual precipitation will increase in both the deep tropics and in temperate zones, but will decrease in the subtropics. However, it’s important to know how the frequency and magnitude of extreme precipitation events will be affected, as these heavy downpours can lead to increased flooding and soil erosion.

It is the frequency of these extreme events that was the subject of this new research, which will appear online in the Proceedings of the National Academy of Sciences during the week of Aug. 17. The report was written by Paul O’Gorman, assistant professor in the Department of Earth, Atmospheric and Planetary Sciences at MIT, and Tapio Schneider, professor of environmental science and engineering at Caltech.

Model simulations used in the study suggest that precipitation in extreme events will go up by about 6 percent for every one degree Celsius increase in temperature. Separate projections published earlier this year by MIT’s Joint Program on the Science and Policy of Global Change indicate that without rapid and massive policy changes, there is a median probability of global surface warming of 5.2 degrees Celsius by 2100, with a 90 percent probability range of 3.5 to 7.4 degrees.

Specialists in the field called the new report by O’Gorman and Schneider a significant advance. Richard Allan, a senior research fellow at the Environmental Systems Science Centre at Reading University in Britain, says, “O’Gorman’s analysis is an important step in understanding the physical basis for future increases in the most intense rainfall projected by climate models.” He adds, however, that “more work is required in reconciling these simulations with observed changes in extreme rainfall events.” The basic underlying reason for the projected increase in precipitation is that warmer air can hold more water vapor. So as the climate heats up, “there will be more vapor in the atmosphere, which will lead to an increase in precipitation extremes,” O’Gorman says.

However, contrary to what might be expected, extremes events do not increase at the same rate as the moisture capacity of the atmosphere. The extremes do go up, but not by as much as the total water vapor, he says. That is because water condenses out as rising air cools, but the rate of cooling for the rising air is less in a warmer climate, and this moderates the increase in precipitation, he says.

The reason the climate models are less consistent about what will happen to precipitation extremes in the tropics, O’Gorman explains, is that typical weather systems there fall below the size limitations of the models. While high and low pressure areas in temperate zones may span 1,000 kilometers, typical storm circulations in the tropics are too small for models to account for directly. To address that problem, O’Gorman and others are trying to run much smaller-scale, higher-resolution models for tropical areas.

Listening to rocks helps researchers better understand earthquakes

When Apollo punished King Midas by giving him donkey ears, only the king and his barber knew. Unable to keep a secret, the barber dug a hole, whispered into it, “King Midas has donkey ears,” and filled the hole. But plants sprouted from the hole, and with each passing breeze, shared the king’s secret.

Earth, as it turns out, has other secrets to divulge. From the pounding of the surf and the rumbling of thunder, to the gentle rustling of leaves, Earth is not a quiet planet. The key is knowing how to listen to the ever-present ambient noise.
University of Illinois seismologist Xiaodong Song and graduate student Zhen J. Xu have become good listeners, especially to the sounds beneath our feet.

Using a technique called “ambient noise correlation,” Xu and Song have observed significant changes in the behavior of parts of Earth’s crust that were disturbed by three major earthquakes.

“The observations are important for understanding the aftermath of a major earthquake at depth,” Song said, “and for understanding how the rock recovers from it and begins again to accumulate stress and strain for future earthquakes.”

The pair report their findings in a paper accepted for publication in the Proceedings of the National Academy of Sciences, and posted on the journal’s Web site.

Researchers have used ambient noise to image Earth’s interior and to monitor changes in seismic velocity near active volcanoes.

Xu and Song used the technique to examine how surface waves (extracted from ambient noise) between seismic stations change with time, because of earthquake-induced changes in the surrounding rock.

Xu and Song were not measuring the time it took for earthquake waves to travel from the epicenter to a seismic station. Rather, they were measuring the time it took for surface waves to travel from one station to another. Because the distance between stations is fixed, the technique allowed researchers to detect very tiny changes in seismic velocity.

“The observations allow us to see not just what happened at the surface, but what happened at depth, and how it affects not just the rupture area, but also the surrounding area,” Xu said.

In their study, the researchers examined the three largest and most recent earthquakes in Sumatra, Indonesia. The earthquakes took place on Dec. 26, 2004; March 28, 2005; and Sept. 12, 2007.

The earthquakes occurred along the Sumatra subduction zone, where a portion of the Indian tectonic plate dives beneath the Eurasian plate. Fault rupture lengths ranged from 450 kilometers for the 2007 earthquake to 1,200 kilometers for the 2004 earthquake.

“We observed a clear change in surface wave velocity over a large area after each of the earthquakes,” Xu said.

In one set of measurements, for example, a surface wave traveling between two particular seismic stations normally required 600 seconds to complete the journey. Following the 2005 earthquake, this time shifted by 1.44 seconds, which is a significant change. But, in all cases, the seismic velocities returned to normal levels within two to three months, indicating that elastic properties in the surrounding rock had recovered.

The most plausible explanation for the time shifts, the researchers write, is increased stress and relaxation in Earth’s upper crust in the immediate vicinity of the rupture, as well as in the broad area near the fault zone. Using ambient noise correlation, the researchers can observe changes in stress several hundreds of kilometers from the source region.

The researchers also observed an unusual time shift that took place a month before the 2004 earthquake. More data is needed, however, to draw a conclusion and to determine whether it was a precursory signal to a major earthquake.

To that end, Xu and Song are studying last year’s devastating earthquake in Wenchuan county in southwest China. An abundance of data was recorded at nearly 300 seismic stations in the source region by seismologists in China. The analysis of respective time shifts will help the researchers better understand how the fault and surrounding behaved before and after the earthquake.

“We need to densify our monitoring network,” Song said. “With this natural source that’s on all the time, and enough paths between different seismic stations, we can see not only changes in time, but also changes in space. So we can have a spatial and temporal image of what’s going on both before and after a major earthquake.”

Antarctic glacier thinning at alarming rate

The Pine Island Glacier in West Antarctica
The Pine Island Glacier in West Antarctica

The thinning of a gigantic glacier in Antarctica is accelerating, scientists warned today.

The Pine Island Glacier in West Antarctica, which is around twice the size of Scotland, is losing ice four times as fast as it was a decade years ago.

The research, published in the journal Geophysical Research Letters, also reveals that ice thinning is now occurring much further inland.At this rate scientists estimate that the main section of the glacier will have disappeared in just 100 years, six times sooner than was previously thought.

The Pine Island Glacier is located within the most inaccessible area of Antarctica – over 1000 km from the nearest research base – and was for many years overlooked. Now, scientists have been able to track the glacier’s development using continuous satellite measurements over the past 15years.

“Accelerated thinning of the Pine Island Glacier represents perhaps the greatest imbalance in the cryosphere today, and yet we would not have known about it if it weren’t for a succession of satellite instruments,” says Professor Andrew Shepherd, a co-author of the research from the School of Earth and Environment at the University of Leeds.

“Being able to assemble a continuous record of measurements over the past 15 years has provided us with the remarkable ability to identify both subtle and dramatic changes in ice that were previously hidden,” he adds.

Scientists believe that the retreat of glaciers in this sector of Antarctica is caused by warming of the surrounding oceans, though it is too early to link such a trend to global warming.

The 5,400 km squared region of the Pine Island Glacier affected today is big enough to impact the rate at which sea level rise around the world.

“Because the Pine Island Glacier contains enough ice to almost double the IPCC’s best estimate of 21st century sea level rise, the manner in which the glacier will respond to the accelerated thinning is a matter of great concern ” says Professor Shepherd.

GPS helps locate soil erosion pathways

Grassed waterways are placed in agricultural fields where runoff water tends to concentrate because they can substantially reduce soil erosion. Mapping techniques that help identify where erosion channels will likely form could help farmers and conservation professionals do a better job of designing and locating grassed waterways in agricultural fields.

Tom Mueller, associate professor in the University of Kentucky (UK), College of Agriculture, guided Adam Pike, UK graduate student, on a project that examined whether reliable prediction models could be created to identify eroded waterways from digital terrain information such as landscape curvature and estimates of water flow from upslope areas.

“The terrain attributes were calculated from elevation data obtained with survey-grade GPS measurements collected on a farm in the Outer Bluegrass Region of Kentucky,” Mueller explains.

Results from the study are published in the September-October issue of Agronomy Journal. This work supported by a special grant from the U.S. Department of Agriculture.

The authors developed equations that accurately identified the potential locations of erosion-prone areas. They found that simple regression methods could be used to fit these equations as well as more complex non-linear neural-network procedures. The equations were used to map areas in fields where erosion was predicted. These areas corresponded very well with actual field observations of erosion. This work was confirmed with a leave-one-field-out validation procedure.

Research showed these maps could help conservation planners and farmers identify where erosion from concentrated flow is likely to occur, but not necessarily the exact shapes of these features. Field site-assessments would still likely be required for verification and to accurately delineate the boundaries of erosion-prone areas.

Mueller stated, “while this study is promising, more work is needed to determine whether these techniques can also be used with USGS digital elevation grids and from elevation data obtained with light detecting and ranging (LIDAR) data. Further, we need to evaluate whether models can be developed to predict across larger geographic areas.”

Mueller is conducting follow-up research to evaluate quality of erosion predictions created with 10-m USGS data sets and evaluating the performance of these models on fields in western Kentucky. He hopes to present the results of some of this work at the 2009 Annual American Society of Agronomy Meetings.

Hiking, horses and helicopter: Scientists deploy seismic network for study of Sierra Negra, Galapagos

An interdisciplinary team of scientists from the University of Miami, University of Rochester, University of Idaho-Moscow and the Instituto Geofísico, Escuela Politécnica Nacional (Quito, Ecuador) joined forces to study one the world's most active volcanoes, Sierra Negra in the Galápagos.  Each site includes a seismometer, battery and solar panel, and electronics to continuously record ground vibrations from local and distant earthquakes. The broadband seismometers were provided by the PASSCAL instrument center and will record data for the next three years. -  Falk Amelung, University of Miami
An interdisciplinary team of scientists from the University of Miami, University of Rochester, University of Idaho-Moscow and the Instituto Geofísico, Escuela Politécnica Nacional (Quito, Ecuador) joined forces to study one the world’s most active volcanoes, Sierra Negra in the Galápagos. Each site includes a seismometer, battery and solar panel, and electronics to continuously record ground vibrations from local and distant earthquakes. The broadband seismometers were provided by the PASSCAL instrument center and will record data for the next three years. – Falk Amelung, University of Miami

An interdisciplinary team of scientists from the University of Miami (UM), University of Rochester, University of Idaho-Moscow and the Instituto Geofísico, Escuela Politécnica Nacional (Quito, Ecuador) have joined forces to study one the world’s most active volcanoes, Sierra Negra in the Galápagos. The volcano’s last eruption occurred in 2005, deepening its 8 km (~5 mile) wide caldera by 4 – 5 meters (~13 – 16 feet). The previous eruption in 1979 produced more than 1 km3 (~0.7 miles3) of lava and was one of the largest eruptions of the 20th century.

The team consists of Dr. Falk Amelung, associate professor of Marine Geology and Geophysics at UM’s Rosenstiel School of Marine and Atmospheric Science; seismologists Dr. Cindy Ebinger of the University of Rochester and Dr. Mario Ruiz of the Instituto Geofísico, Escuela Politécnica Nacional de Quito; volcanologist Dr. Dennis Geist of the University of Idaho (Moscow); science teacher Lisa Hjelm from The Girls’ Middle School in Mountain View, California; Escuela Politécnica Nacional undergraduate geology student Daniel Pacheco; and Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL) engineer Eliana Arias-Dotson. They returned from an adventure that lasted nearly three weeks, which included hiking, riding horses and navigating dangerous waters to deploy an experimental seismic network of 16 stations around Isla Isabela, Galápagos. The broadband seismometers provided by the PASSCAL instrument center will record data for the next three years.

“With the satellite data we regularly collect here at the University of Miami, using a technique called satellite radar interferometry, we are able to see the underground location of the magma chamber. The new seismic data will allow us to corroborate our information and obtain proof that the magma chamber is actually 2 km. (~1.2 miles) down and to what depth it extends,” said Amelung. “Petrologists suggest that the chamber may extend to a depth of 10 km. (~6.2 miles), whereas geophysicists believe it might go only to a depth of 3 km. (1.8 miles) or so.” These new seismic data will be analyzed to provide the first 3-D pictures of the volcanic plumbing system, completing the picture derived from satellite and rock studies.

The team conducted eight dry and wet landings from a boat, placing sites along the coastline. The Galápagos-based Charles Darwin Foundation and Parque Nacional de Galápagos, both celebrating their 50th anniversary in 2009, assisted in providing horses and other support to transport equipment to more remote regions of Isla Isabela. However, the most challenging deployment took place in the center of the caldera, where scientists had to hike over miles of sharp, jagged igneous rock from the last lava flow. Geist arranged for a helicopter to fly the heavy equipment to a central drop site so they could navigate the unforgiving terrain, which tore into their hiking boots and required heavy duty work gloves to traverse.

Once set up, each site included a seismometer that had to be precisely leveled, a battery and solar panel, and electronics to continuously record ground vibrations from local and distant earthquakes. A number of the sensitive instruments were buried, but in areas where hard volcanic rock was present, the stations were left above ground and protected by rocks and other natural features.

The integrated seismic-geodetic study of the active magmatic processes at Sierra Negra volcano was funded by the National Science Foundation (NSF). An additional NSF grant was awarded to Hjelm for education and outreach. Her intent is to use data from this study to create a visualization of the interior of the volcano as an educational product for teens.