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

New Study Confirms Water Vapor as Global Warming Amplifier

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New Study Confirms Water Vapor as Global Warming Amplifier


Special to UM News

Color enhanced satellite image of upper tropospheric water vapor. Photo courtesy of NASA.

Color enhanced satellite image of upper tropospheric water vapor. Photo courtesy of NASA.

MIAMI, Fla. (July 28, 2014)—A new study from scientists at the Rosenstiel School of Marine and Atmospheric Science and colleagues confirms rising levels of water vapor in the upper troposphere—a key amplifier of global warming—will intensify the impact of climate change over the next decades.

“The study is the first to confirm that human activities have increased water vapor in the upper troposphere,” said Brian Soden, professor of atmospheric sciences and co-author of the study. Read the full story

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Collateral Damage: Study Reveals Sharks Most Vulnerable to Commercial Fishing

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Collateral Damage: Study Reveals Sharks Most Vulnerable to Commercial Fishing


Shark.Bycatch.Study

Special to UM News

MIAMI, Fla. (July 22, 2014)—A new study that examined the survival rates of 12 different shark species captured as unintentional bycatch in commercial longline fishing operations found large differences across the 12 species, with bigeye thresher, dusky, and scalloped hammerhead being the most vulnerable. Led by researchers at the Rosenstiel School of Marine and Atmospheric Science and the Abess Center for Ecosystem Science and Policy, the study provides new information to consider for future shark conservation measures in the northwest Atlantic. The unintentional capture of one fish species when targeting another, known as bycatch, is one of the largest threats facing many marine fish populations.

Researchers from the University of Miami and the National Marine Fisheries Service analyzed over 10 years of shark bycatch data from western Atlantic Ocean and Gulf of Mexico tuna and swordfish longline fisheries to examine how survival rates of sharks were affected by fishing duration, hook depth, sea temperature, animal size, and the target fish. Some species, such as tiger sharks, had bycatch survival rates that exceeded 95 percent, while other species, such as night sharks and scalloped hammerheads, had significantly lower survival rates— in the 20 to 40 percent range.

“Our study found that the differences in how longline fishing is actually conducted, such as the depth, duration, and time of day that the longlines are fished, can be a major driver of shark survival, depending on the species,” said Austin Gallagher, a Rosenstiel School Ph.D. student and lead author of the study. “At-vessel mortality is a crucial piece of the puzzle in terms of assessing the vulnerability of these open-ocean populations, some of which are highly threatened.”

The researchers also generated overall vulnerability rankings of species, taking into account not only their survival, but also reproductive potential. They found that species most at risk were those with both very slow reproductive potential and unusual body features, such as hammerheads and thresher sharks. The study authors suggest that bycatch likely played an important role in the decline of scalloped hammerhead species in the northwest Atlantic, which has been considered for increased international and national protections, such as the U.S. Endangered Species List.

The researchers suggest that high at-vessel mortality, slow maturity, and specialized body structures combine for the perfect mixture to become extinction-prone.

“Our results suggest that some shark species are being fished beyond their ability to replace themselves,” said Neil Hammerschlag, research assistant professor. “Certain sharks, such as bigeye threshers and scalloped hammerheads, are prone to rapidly dying on the line once caught, and techniques that reduce their interactions with fishing gear in the first place may be the best strategy for conserving these species.”

The study, titled “Vulnerability of oceanic sharks as pelagic longline bycatch,” was published online in the open-access journal Global Ecology and Conservation.

In addition to Gallagher and Hammerschlag, from UM’s R.J. Dunlap Marine Conservation Program, coauthors included Joseph Serafy and Eric Orbesen from the National Oceanic and Atmospheric Administration’s Southeast Fisheries Science Center.

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Study Provides New Approach to Forecast Hurricane Intensity

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Study Provides New Approach to Forecast Hurricane Intensity


Brian Haus, professor of ocean sciences, co-authored the study.

Brian Haus, professor of ocean sciences, co-authored the study.

Special to UM News

MIAMI, Fla. (July 18, 2014)— New research  suggests that physical conditions at the air-sea interface, where the ocean and atmosphere meet, is a key component to improve forecast models. The study  from the Rosenstiel School of Marine and Atmospheric Science offers a new method to aid in storm intensity prediction of hurricanes.

“The general assumption has been that the large density difference between the ocean and atmosphere makes that interface too stable to effect storm intensity,” said Brian Haus, professor of ocean sciences and co-author of the study. “In this study we show that a type of instability may help explain rapid intensification of some tropical storms.”

Experiments conducted at the RSMAS Air-Sea Interaction Salt Water Tank (ASIST) simulated the wind speed and ocean surface conditions of a tropical storm. The researchers used a technique called “shadow imaging,” where a guided laser is sent through the two fluids—air and water—to measure the physical properties of the ocean’s surface during extreme winds, equivalent to a category 3 hurricane.

Using the data obtained from the laboratory experiments conducted with the support of the Gulf of Mexico Research Initiative (GOMRI) through the CARTHE Consortium, the researchers then developed numerical simulations to show that changes in the physical stress at the ocean surface at hurricane force wind speeds may explain the rapid intensification of some tropical storms. The research team’s experimental simulations show that the type of instability, known as Kelvin-Helmoltz instability, could explain this intensification.

Haus and colleagues will conduct further studies on hurricane intensity prediction in the new, one-of-a- kind Alfred C. Glassell, Jr., SUSTAIN research facility located at the UM Rosenstiel School. The SUrge-STructure-Atmosphere INteraction laboratory is the only facility capable of creating category 5-level hurricanes in a controlled, seawater laboratory. The nearly 65-foot long tank allows scientists to simulate major hurricanes using a 3-D wave field to expand research on the physics of hurricanes and the associated impacts of severe wind-driven and wave-induced storm surges on coastal structures.

The SUSTAIN research facility is the centerpiece of the new $45 million Marine Technology and Life Sciences Seawater Complex at the Rosenstiel School where scientists from around the world have access to state-of-the-art seawater laboratories to conduct an array of marine-related research.

The study, titled “The air-sea interface and surface stress under tropical cyclones,” was published in the June 16 issue of the journal Nature Scientific Reports. The paper’s lead author was Alex Soloviev of the Rosenstiel School and Nova Southeastern University Oceanographic Center. Other coauthors include: Mark A. Donelan, from the Rosenstiel School; Roger Lukas of the University of Hawaii; and Isaac Ginis from the University of Rhode Island.

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UM Study Provides New Insights into Deeper Reefs

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UM Study Provides New Insights into Deeper Reefs


In a new study, UM researchers compare bioerosion on deeper reef systems to better understand long-term structural sustainability.

Researcher David Weinstein recovers experimental coral substrates for the bioerosion study at midpath reef site.

Researcher David Weinstein recovers experimental coral substrates for the bioerosion study.

MIAMI – A new University of Miami study of mesophotic tropical coral reefs, which are low-energy reef environments between 30 to 150 meters deep, provides new insights into the differences in bioerosion rates and the distribution of fish, mollusks, sponges, and other bioeroding organisms in mesophotic reefs and their shallow-water counterparts. The study explores the implications of those variations on the sustainability of the reef structure.

Due to major advancements in deeper underwater diving technology, renewed interest in mesophotic reefs has pulsed through the scientific community because of the deeper reefs’ high biodiversity, vast extent, and potential refuge for shallower water reef species at risk from the impacts of climate change.

“Studying how mesophotic reefs function and thrive is especially critical now, when considering results from the new IPCC (Intergovernmental Panel on Climate Change) report reviewed by over 1,700 expects said that coral reefs are the most vulnerable marine ecosystems on earth to the adverse effects of climate change,” said David Weinstein, a Ph.D. candidate at the Rosenstiel School of Marine and Atmospheric Science and lead author of the study, now available online in the journal Geomorphology.

“Developing effective environmental management strategies for these important reef systems requires a basic fundamental understanding of the underlining architecture that supports and creates diverse biological ecosystems.”

Weinstein and his research team used previously identified mesophotic reefs in the U.S. Virgin Islands that are at 30 to 50 meters deep and composed of a surprising number of coral growing atop different types of reef structures (patches, linear banks, basins). Their aim was to better understand the role sedimentary processes play in creating and maintaining the variety of structures that are critical for maximizing the biodiversity and health of the ecosystem. The researchers analyzed coral rubble and coral skeleton discs collected after one and two years of exposure to determine the sources and rates of bioerosion at these reefs.

They found that architecturally unique structures in the study area experience significantly different bioerosion rates.

“This has very important implications when trying to predict how these reefs will grow over time and where preservation efforts might be most effective,” said Weinstein.

Although erosion of the coral skeleton disks at the very deepest sites was more uniform, the researchers suggest that this is likely because the substrates used in the study were all of uniform composition, unlike the diverse composition of the sites. These results imply that bioerosional processes at these depths still exaggerate differences in reef structure depending on the amount of living and dead coral at each reef, the amount of time that material is exposed on the surface, and different localized current flows experienced.

The study also confirmed important concepts in coral geology research that lacked proof from studies venturing deeper than 35 meters. Coral reef bioerosion in the U.S. Virgin Islands and potentially in most of the Caribbean generally decreases with depth. This result stems from the finding that parrotfish are now the most significant bioeroding group from shallow reefs down to a mesophotic reef transition zone identified by Weinstein at 30 to 35 meters in depth.

The study also concluded that bioeroding sponges are the primary organisms responsible for long-term structural modification of mesophotic reefs beyond the transitional zone.

“Coral reefs are essentially a thin benthos veneer draped upon a biologically produced inorganic three-dimensional foundation that creates habitats for many marine organisms,” said Weinstein. “Since mesophotic reefs grow so much slower than shallower reefs, identifying the sources and rate of erosion on mesophotic reefs is even more important to understand the long-term structural sustainability of these tropical reefs systems.”

However, Weinstein suggests that other processes, such as coral growth rates and cementation, must also be more fully studied before scientists have a complete understanding of mesophotic coral reefs.

The paper, which is also slated for print in a special coral reef edition of Geomorphology, is one of the first to address mesophotic reef sedimentology.

More information, videos, pictures, and new developments can be found at the UM Mesophotic Geology Lab  website and on Facebook.

 

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President Shalala Weighs in on ‘The Risky Business’ of Climate Change

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President Shalala Weighs in on ‘The Risky Business’ of Climate Change


By Megan Ondrizek
UM News

UM President Donna E. Shalala.

UM President Donna E. Shalala.

CORAL GABLES, Fla. (June 24, 2014) — On Tuesday, University of Miami President Donna E. Shalala joined the debate on climate change as a member of The Risky Business Project, a joint, non-partisan initiative. Shalala partnered with fellow former political leaders to discuss global trends and the economic risks of climate change. Read the full story

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