Tag Archive | "rosenstiel school of marine and atmospheric science"

As the Climate Warms, the Indian Ocean’s Mighty Agulhas Current Widens


As the Climate Warms, the Indian Ocean’s Mighty Agulhas Current Widens

The  Rosenstiel School Agulhas Current study has important implications for global climate.

CORAL GABLES, Fla. (November 14, 2016)—A new study by researchers at the  Rosenstiel School of Marine and Atmospheric Science found that the Indian Ocean’s Agulhas Current is getting wider rather than strengthening. The findings, which have important implications for global climate change, suggest that intensifying winds in the region may be increasing the turbulence of the current, rather than increasing its flow rate.

Using measurements collected during three scientific cruises to the Agulhas Current, the Indian Ocean’s version of the Gulf Stream, researchers estimated the long-term transport of the current leveraging 22 years of satellite data. They found the Agulhas Current has broadened, not strengthened, since the early 1990s, due to more turbulence from increased eddying and meandering.

One of the strongest currents in the world, the Agulhas Current flows along the east coast of South Africa, transporting warm, salty water away from the tropics toward the poles. The Agulhas, which is hundreds of kilometers long and over 2,000-meters deep, transports large amounts of ocean heat and is considered to have an influence not only on the regional climate of Africa, but on global climate as part of the ocean’s global overturning circulation.

“Changes in western boundary currents could exacerbate or mitigate future climate change,” said Lisa Beal, a UM Rosenstiel School professor of ocean sciences and lead author of the study. “Currently, western boundary current regions are warming at three times the rate of the rest of the world ocean and our research suggests this may be related to a broadening of these current systems.”

Previous studies have suggested that accelerated warming rates observed over western boundary current regions, together with ongoing strengthening and expansion of the global wind systems predicted by climate models relate to an intensification and pole-ward shift of western boundary currents as a result of man-made climate change.

“To find decades of broadening, rather than intensification, profoundly impacts our understanding of the Agulhas Current and its future role in climate change,” said study co-author Shane Elipot, a UM Rosenstiel School associate scientist. “Increased eddying and meandering could act to decrease poleward heat transport, while increasing coastal upwelling and the exchange of pollutants and larvae across the current from the coast to the open ocean.”

This paper analyzed data collected during the “Agulhas Current Times-Series” experiment, led by Beal and funded by the National Science Foundation. The experiment produced continuous measurements of the Agulhas Current to better understand how the oceans are changing due to climate change.

The study, titled “Broadening not strengthening of the Agulhas Current since the early 1990s,” was published November 9, in the Advance Online Publication of the journal Nature. The authors of the study are Beal and Elipot. DOI: 10.1038/nature19853. Funding was provided the US National Science Foundation, grant OCE-085089.

Visit the University of Miami’s report on climate change,

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Study Reveals Earthquake Hazard


Study Reveals Earthquake Hazard

Special to UM News


These satellite images, obtained from the Envisat satellite, shows (left) the Western India plate boundary zone, which includes the Chaman fault and Kabul, and (right) a ground velocity field of the Ghazaband fault and Quetta.

MIAMI, Fla. (September 27, 2016) — Scientists at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science have revealed alarming conclusions about the earthquake hazard in the Afghanistan-Pakistan border region. The new study focused on two of the major faults in the region—the Chaman and Ghazaband faults.

“Typically earthquake hazard research is a result of extensive ground-based measurements,” said Heresh Fattahi, the study’s lead author and a Rosenstiel School alumnus. “These faults, however, are in a region where the political situation makes these ground-based measurements dangerous and virtually impossible.”

Using satellite data from 2004-2011 acquired by the European Space Agency satellite Envisat and through a technique called interferometry, the researchers were able to measure the relative motion of the ground and then model the movement of the underlying faults with an accuracy of just a few millimeters. Using data for a seven-year timeframe and employing time-series analysis techniques helped increase the confidence in their results.

The new study shows that the Ghazaband fault is accommodating more than half of the relative motion between the Indian and Eurasian tectonic plates, which indicates that the fault accumulates stress, making the potential for a high-magnitude earthquake much higher than previously thought.

Quetta, the capital of Pakistan’s Balochistan province located close to the Ghazaband Fault, lost nearly half of its population following a magnitude 7.7 earthquake in 1935.

“Quetta’s population of more than one million is in serious danger if an earthquake were to strike,” said Falk Amelung, a Rosenstiel School professor of geophysics and a coauthor of the study. “Earthquake-proof construction is vital in avoiding earthquake disasters. Quetta, as well as other cities in the region, is completely unprepared.”

The research team also studied the Chaman Fault, the largest fault in the region, running from southern Pakistan to north of Kabul, Afghanistan’s capital. This fault was thought to accommodate the lion’s share of the relative plate motion, but the satellite data reveal that it may account for only about one third of it. “We have to rethink the tectonics of the region,” said Amelung.

The researchers also found a creeping segment, where the rock masses slide against each other without accumulating any stress that would lead to earthquakes. The creeping fault extends for 340 kilometers (211 miles). “This is the longest creeping fault ever reported,” said Fattahi.

The slower-than-expected fault rate and the presence of the long creeping segment explain why the region has not, for over 500 years, experienced major earthquakes with fault ruptures from several tens to several hundreds of kilometers. However, scientists warn, this does not mean there is no hazard.

The study, titled “InSAR observations of strain accumulation and fault creep along the Chaman Fault system, Pakistan and Afghanistan,” by Fattahi and Amelung appeared in the August 22 issue of the journal Geophysical Research Letters. NASA’s Earth Surface and Interior program and the National Science Foundation’s Tectonics Program funded the study.


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Researchers Take to the Air to Hunt Shipwrecks at Sea

Special to UM News


The University’s Helicopter Observation Platform will conduct aerial shipwreck surveys.

MIAMI—A research team led by the Rosenstiel School of Marine and Atmospheric Science has been awarded funding from the National Geographic Society to conduct aerial shipwreck surveys in Biscayne National Park using technology on its specially designed helicopter. The project will begin in October and run through August 2017.

The research team, led by Frederick “Fritz” Hanselmann, director of UM’s Underwater Archaeology and Underwater Exploration program, and Charles Lawson, Biscayne National Park’s cultural resources manager and archaeologist, will use the  Rosenstiel School’s one-of-a-kind Helicopter Observation Platform (HOP) to conduct aerial geomagnetic surveys to identify potential marine archaeological sites located in the South Florida-based national park.

The test-of-concept project will use advances in airborne and underwater technologies to conduct a rapid assessment to identify potential archaeological sites followed by ground-truthing of aerial results with diver-led visual surveys. Rosenstiel School Dean Roni Avissar will serve as chief pilot and UM Professor and National Geographic Explorer Kenny Broad as co-pilot for flight operations. Bert Ho, senior underwater archaeologist with the National Park Service’s Submerged Resources Center, will be the project’s geophysical expert, along with a representative of Geometrics LLC, and will deploy an airborne magnetometer from the HOP to acquire the data that could lead to the discovery of more shipwrecks in the park.

“If successful, this approach could be a game changer in our ability to rapidly identify and archive submerged cultural resources,” said Hanselmann.

The commercial Airbus Helicopters H125 aircraft that will be used in the study is capable of collecting critical scientific information at the Earth’s surface, whether marine or continental, and the thin atmospheric boundary layer above it. Fully fueled and with both pilot and co-pilot on board, the HOP can carry a scientific payload of up to 1,000 pounds internally (about 2,000 pounds externally) and fly for nearly four hours without refueling at an airspeed of 65 knots. Its fast cruising speed is 140 knots and its range, at that speed, is 350 nautical miles. The Geometrics magnetometer is used to pick up ferrous or metallic differences from the region’s magnetic signature, which have the potential to be historic shipwrecks.

The project will provide significantly more information to park officials on the 50,000 acres of unsurveyed area within Biscayne National Park and allow increased research and protection of critical heritage sites. Over 40 shipwrecks are located within the waters of Biscayne National Park, ranging from 350-foot-long iron steamers and single colonial anchors to 17th century sailing vessels built primarily of wood.

The researchers will use data obtained from previous boat-towed geomagnetic surveys to compare the effectiveness of helicopter-based aerial survey as an underwater archeological method. “If proven effective, this survey model can translate to other, more difficult areas for archaeological survey and ocean exploration,” said Hanselmann.

Additionally, National Geographic fellow Corey Jaskolski will create detailed maps using a 3D image-based scanning based on photogrammetry, which takes many high-resolution underwater images using a calibrated camera system stitched together into incredibly high-resolution 3D models. The image maps will be shared interactively for student or scientist study within virtual or augmented reality, or 3D printed to scale for accurate measurement and analysis.

The study, titled: “A Baseline Characterization of Biscayne National Park’s Submerged Cultural Resources Utilizing Aerial Geomagnetic Survey and Underwater 3-D Imaging,” was funded by a grant from the National Geographic Society’s Expeditions Council.


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Altered Brain Chemistry, Behavior Linked to Elevated CO2


Altered Brain Chemistry, Behavior Linked to Elevated CO2

Special to UM News

Research team studied damselfish behavior and physiology under ocean acidification conditions predicted for year 2300


Spiny damselfish swim in the Lizard Island coral reef.                                   Photo by Jodie L. Rummer


MIAMI, Fla. (September 13, 2016)—In a first-of-its-kind study, researchers from the  Rosenstiel School of Marine and Atmospheric Science and the ARC Centre of Excellence for Coral Reef Studies at James Cook University showed that increased carbon dioxide concentrations alter brain chemistry that may lead to neurological impairment in some fish.

Understanding the impacts of increased carbon dioxide levels in the ocean, which is turning the ocean more acidic, allows scientists to better predict how fish will be impacted by future ocean acidification conditions.

“Coral reef fish, which play a vital role in coral reef ecosystems, are already under threat from multiple human and natural stressors,” said lead author Rachael Heuer, a Rosenstiel School alumna who conducted the study as part of her Ph.D. work. “By specifically understanding how brain and blood chemistry are linked to behavioral disruptions during CO2 exposure, we can better understand not only what may happen during future ocean acidification scenarios, but why it happens.”

In this study, the researchers designed and conducted a novel experiment to directly measure behavioral impairment and brain chemistry of the spiny damselfish (Acanthochromis polyanthus), a fish commonly found on coral reefs in the western Pacific Ocean.

During a three-week period, the scientists collected spiny damselfish from reefs off Lizard Island on Australia’s Great Barrier Reef. The fish were separated into two groups—those exposed to ordinary CO2 “control” conditions and those exposed to elevated CO2 levels that are predicted to occur in the near future but have already been observed in many coastal and upwelling areas throughout the world. Following the exposure, the fish were subjected to a behavioral test, and their brain and blood chemistry were measured.

The unique behavioral test employed a two-choice flume system, where fish were given the choice between control seawater or water containing a chemical alarm cue, which they typically avoid since it represents the smell associated with an injured fish of its own species.

The researchers found that the damselfish exposed to elevated carbon dioxide levels were spending significantly more time near the chemical alarm cue than the control fish, a behavior that would be considered abnormal. The measurements of brain and blood chemistry provided further evidence that elevated CO2 caused the altered behavior of the fish.

“For the first time, physiological measurements showing altered chemistry in brain and blood have been directly linked to altered behavior in a coral reef fish,” said senior author Martin Grosell, the Rosenstiel School’s Maytag Professor of Ichthyology and lead of the RECOVER Project. “Our findings support the idea that fish effectively prevent acidification of internal body fluids and tissues, but that these adjustments lead to downstream effects including impairment of neurological function.”

“If coral reef fish do not acclimate or adapt as oceans continue to acidify, many will likely experience impaired behavior that could ultimately lead to increased predation risk and to negative impacts on population structure and ecosystem function,” said Heuer, currently a postdoctoral researcher at the University of North Texas. “This research supports the growing number of studies indicating that carbon dioxide can drastically alter fish behavior, with the added benefit of providing accurate measurements to support existing hypotheses on why these impairments are occurring.”

The study, titled “Altered brain ion gradients following compensation for elevated COare linked to behavioural alternations in a coral reef fish,” was published in the September 13 online issue of the journal Scientific Reports. In addition to Heuer and Grosell, the study’s coauthors are Megan J. Welch, Jodie L. Rummer, and Philip L. Munday from the ARC Centre of Excellence for Coral Reef Studies at James Cook University.

The National Science Foundation, a University of Miami Koczy Fellowship, and the ARC Centre of Excellence provided funding support for the study. Heuer was also funded by an NSF Graduate Research Fellowship to conduct the research.

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Study Finds Shark Fins and Meat Contain Neurotoxins Linked to Alzheimer’s

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Study Finds Shark Fins and Meat Contain Neurotoxins Linked to Alzheimer’s

UM research team says restricting shark consumption protects human health and shark populations

Researchers detected cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) and mercury in sharks from the Atlantic and Pacific Oceans.

Researchers detected cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) and mercury in sharks from the Atlantic and Pacific Oceans.

MIAMI—In a new study, University of Miami scientists found high concentrations of toxins linked to neurodegenerative diseases in the fins and muscles of 10 species of sharks. The research team suggests that restricting consumption of sharks can have positive health benefits for consumers and for shark conservation, since several of the sharks analyzed in the study are threatened with extinction due to overfishing.

Fins and muscle tissue samples were collected from 10 shark species found in the Atlantic and Pacific Oceans for concentrations of two toxins—mercury and β-N-methylamino-L-alanine (BMAA). “Recent studies have linked BMAA to neurodegenerative diseases such as Alzheimer’s disease and amyotrophic lateral sclerosis (ALS),” said Deborah Mash, professor of neurology at the Miller School of Medicine and senior author of the study.

Researchers at the  Rosenstiel School of Marine and Atmospheric Science and the Miller School detected concentrations of mercury and BMAA in the fins and muscles of all shark species at levels that may pose a threat to human health. While both mercury and BMAA by themselves pose a health risk, together they may also have synergistic toxic impacts.

“Since sharks are predators, living higher up in the food web, their tissues tend to accumulate and concentrate toxins, which may not only pose a threat to shark health, but also put human consumers of shark parts at a health risk,” said the study’s lead author Neil Hammerschlag, research assistant professor at the Rosenstiel School and Abess Center for Ecosystem Science and Policy.

Shark products, including shark fins, cartilage, and meat, are widely consumed in Asia and in Asian communities globally as a delicacy and as a source of traditional Chinese medicine. In addition, dietary supplements containing shark cartilage are consumed globally.

Recently scientists found BMAA in shark fins and shark cartilage supplements. The neurotoxic methyl mercury has been known to bioaccumulate in sharks over their long lifespans.

About 16 percent of the world’s shark species are threatened with extinction. The shark species sampled in this study range in threat status from least concern (bonnethead shark) to endangered (great hammerhead) by the International Union for Conservation of Nature (IUCN).

“Our results suggest that humans who consume shark parts may be at a risk for developing neurological diseases,” Mash said.

“People should be aware and consider restricting consumption of shark parts,” Hammerschlag said.   “Limiting the consumption of shark parts will have positive health benefits for consumers and positive conservation outcomes for sharks, many of which are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products.”

The study, titled “Cyanobacterial Neurotoxin BMAA and Mercury in Sharks,” was published August  16 in the journal Toxins. IN addition to Mash and Hammerschlag, the study coauthors include David A. Davis, Kiyo Mondo, and Matthew S. Seely, from the Miller School’s Department of Neurology; Susan J. Murch and William Broc Glover from the University of British Columbia; and Timothy Divoll and David C. Evers from the Biodiversity Research Institute in Maine. The Herbert W. Hoover Foundation provided the funding for this study.

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