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Study Shows Ocean Acidification Accelerates Reef Erosion


Researchers found that increased activity by worms and other organisms act on coral skeletons

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A coral skeleton sample from the study and its 3D reconstructions show the external surface in gray, the CT-scan analysis of new structure added in green on the outside, and boreholes from worms showing structure loss on the inside (in blue).

MIAMI, Fla. (November 21, 2016)—Scientists studying naturally high carbon dioxide coral reefs in Papua New Guinea found that erosion of essential habitat is accelerated in these highly acidified waters, even as coral growth continues to slow. The new research by Rosenstiel School of Marine and Atmospheric Science’s Cooperative Institute for Marine and Atmospheric Studies (CIMAS), the National Oceanic and Atmospheric Administration (NOAA), and the Australian Institute of Marine Science has important implications for coral reefs around the world as climate change makes the ocean more acidic.

The study, published in the journal Proceedings of the Royal Society B, measured changes in the structural habitat at two reefs in volcanically acidified waters off remote Papau New Guinea and, for the first time, found increased activity of worms and other organisms that bore into the reef structure, resulting in a loss of the framework that is the foundation of coral reef ecosystems.

These “champagne reefs” are natural analogs of how coral reefs may look in 100 years if carbon dioxide continues to rise and ocean acidification conditions continue to worsen.

“This is the first study to demonstrate that ocean acidification is a two-front assault on coral reefs, simultaneously slowing the growth of skeleton, and speeding up the rate at which old reef habitats are eroded,” said Ian Enochs, a coral ecologist at CIMAS and NOAA’s Atlantic Oceanographic and Meteorological Laboratory and lead author of the study.

Enochs placed pieces of coral skeleton alongside these “champagne reefs” for two years to allow diverse coral reef communities to settle on them and to understand how reefs respond to ocean acidification conditions.

Using high-resolution CT scans similar to those taken at hospitals, the scientists created 3D models of the coral skeletons to peer inside them and see the bore holes left by worms and other organisms. These scans allowed them to measure the difference between new coral material added by calcifying organisms and coral material lost through bio-erosion.

The analysis found that a net loss of coral reef skeletons was occurring due to increased bio-erosion and at the pH tipping point of 7.8, reef frameworks in this region will begin to dissolve away.

“At these reefs, carbon dioxide from subterranean volcanic sources bubble up through the water, creating conditions that approximate what the rest of the world’s oceans will experience due to ocean acidification,” said Enochs. “This is the first study to piece together all of the separate coral reef ocean acidification processes, simultaneously looking at the different organisms that grow and erode reef habitats, and their net effects on one another over time.”

The study, titled “Enhanced macroboring and depressed calcification drive net dissolution at high-CO2 coral reefs,” was published in the November 15 issue of the journal Proceedings of the Royal Society B.  In addition to Enochs, the study’s co-authors include Graham Kolodziej and Lauren Valentino from UM/CIMAS; Derek P. Manzello from NOAA’s Atlantic Oceanographic and Meteorological Laboratories; and Sam H. C. Noonan and Katharina E. Fabricius from the Australian Institute of Marine Science.

View a 3D animation of the coral cat scan showing erosion and accretion in naturally acidified waters.

 

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

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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

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Study Reveals Earthquake Hazard


Special to UM News

earthquake-study

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

treasure-chopper

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

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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

damselfish-by-jodie-l-rummer

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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