Tag Archives: research

Skidaway Institute graduate students participate on a glider team cruise off Cape Hatteras

Skidaway Institute graduate students Kun Ma and Lixin Zhu recently joined a science cruise on the Research Vessel Savannah off Cape Hatteras, North Carolina. The cruise, which ran from May 31-June 5, was led by Jeffrey Book from the U.S. Naval Research Laboratory. The main objective of this cruise was to test and demonstrate the use of gliders together in teams and to assimilate the data into ocean forecast models. The cruise was 22 days in total, divided into three legs. Ma and Zhu were part of the third leg.

Kun Ma cocking the Niskin bottles on a Conductivity-Temperature-Depth array.

Ma is a new University of Georgia doctoral student at Skidway, working mainly on a National Science Foundation-funded photochemistry project with professors Jay Brandes and Aron Stubbins. This was her first science cruise and she collected some particulate organic matter and dissolved inorganic carbon samples. She also helped Skidaway Institute researcher Bill Savidge by collecting some chlorophyll samples in order to calibrate the chlorophyll sensor on the CTD instrument, an instrument used to collect water samples and measure those samples’ properties, such as Conductivity (a proxy for salinity), Temperature and Depth.

Lixin Zhu in immersion suit during safety trainning

Zhu is a visiting doctoral student in Aron Stubbins’s lab from East China Normal University. He collected filtered water samples on the cruise. Zhu will analyze the color and fluorescence of dissolved organic matter, and dissolved black carbon concentrations. In addition, Zhu performed solid phase extraction and collected high-resolution real-time data on colored organic matter with the underway scientific computer system on the ship. Eventually, he will combine these data with other field data collected in the South Atlantic Bight area to see the overall dynamics of dissolved black carbon.

“I am glad that we overcame seasickness, and it’s really cool to see that the glider team controlled six gliders at the same time aboard,” Zhu said. “Furthermore, their working approach and decision making process, based on real-time data, modeling and satellite results, impressed me a lot.”

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Jay Brandes collaborator on research paper

UGA Skidaway Institute professor Jay Brandes is a collaborator on a recent publication focusing on the roles of methane, iron and microbes in regulating the temperature of the primordial ocean. The research team was led by Georgia Tech Ph.D. student Marcus Bray. An article describing the project, can be found here.

 

UGA Skidaway Institute researchers probe complex Atlantic Ocean currents

Dana Savidge

The ocean off the coast of North Carolina has a complex system of ocean currents that make it one of the least understood areas on the U.S. Eastern Seaboard. University of Georgia Skidaway Institute of Oceanography professor Dana Savidge is leading a team of scientists, including UGA Skidaway Institute scientist Catherine Edwards, working to unravel the mysteries of the complex ocean currents near Cape Hatteras.

The four-year project, informally called PEACH: Processes driving Exchange At Cape Hatteras, was launched in early 2016 and is funded by a $5 million grant from the National Science Foundation to better understand the relationship between the waters of the continental shelf and the deep ocean.

“The U.S. continent, like others, has a shallow ocean immediately around it, called the continental shelf. It’s like an apron that extends out from the shoreline and it is fairly shallow, only about 60 meters deep,” Savidge said. “At its outer edge, the bottom drops sharply into the deep ocean, which can be miles deep.”

Exchange at the shelf edge can push cold, nutrient-rich water from the deep ocean onto the shelf, which drives productivity of marine algae and the food web that it supports.

“There’s a reason people love offshore fishing at the edge of the Gulf Stream,” said Edwards. “Areas with regular exchange of shelf and deep waters are often known hot spots for commercial and recreational fishing.”

One reason Cape Hatteras attracted the researchers’ attention is that two opposing deep ocean currents collide there, making the ocean there highly dynamic. The warm Gulf Stream hugs the edge of the continental shelf as it flows north from the tip of Florida. At Cape Hatteras, the Gulf Stream opposes a colder current, the Slope Sea Gyre current, that moves southward along the mid-Atlantic coast. There, the Gulfstream breaks away from the coast toward northern Europe.

There is a convergence of shelf currents at Cape Hatteras as well, as cool shelf waters of the mid-Atlantic continental shelf meet the warm salty shelf waters from the south. Each of these currents, on the shelf and at the shelf edge, has a distinct temperature, salinity, and often a biological signal that reflects the origin of the water it carries. The team will measure these properties and ocean currents to better understand the exchange processes.

During the first year of the study, the researchers prepared and installed a network of sophisticated, high-tech instruments on the shore and in the ocean to monitor and capture the movement of water and changing properties like temperature and salinity. Together with scientists from the University of North Carolina and North Carolina State University, the team has worked with ocean models to better understand the interaction between shelf currents and the deeper currents of the Gulf Stream and the Slope Sea Gyre.

“Circulation on the continental shelf and the deep ocean can be quite separate things, but their effects on one another can be quite complicated,” Savidge said.
In addition to subsurface packages moored on the sea floor, the PEACH team is taking advantage of modern sampling techniques with shore-based radar systems and autonomous underwater vehicles called gliders to collect data remotely.

Savidge working on a radar antenna on the Outer banks.

Savidge’s hardware contribution to the project is a series of low-power, high-frequency radar stations that scan the waters of the continental shelf and measure the speed and direction of surface currents.

“Measuring surface currents remotely with the radars is a real advantage here,” Savidge said. “They cover regions that are too shallow for mobile vehicles like ships to operate, while providing detailed information over areas where circulation can change quite dramatically over short times and distances.”

An array of radar antennae on an Outer Banks beach.

Savidge’s research technician, Gabe Matthias, installed the radar systems on the beach at Salvo and Buxton, and at the airports at Frisco and Ocracoke, North Carolina. Currently, the researchers are working out the bugs in the system and getting the four stations to work together to paint a composite picture of the surface currents. The radars produce a massive amount of data to be processed.

Edwards leads the effort to use gliders that will operate on the shelf for nearly the entire 16-month experiment. Gliders are shaped like torpedoes and equipped with sensors to measure properties like temperature, salinity and dissolved oxygen. They can be programmed to cruise the underwater environment for weeks at a time, surfacing at regular intervals to transmit its collected data via a satellite phone.

Edwards in her lab with a glider.

Edwards’s specialty is improving the way these gliders sample the coastal waters using information from models and real-time data streams, including surface currents from Savidge’s HF radar. Edwards and doctoral students Qiuyang Tao and Mengxue Hou, co-advised by Edwards and Fumin Zhang of Georgia Tech, have developed new systems that optimize the path of the gliders based on near real-time information about current patterns and how they are expected to change, making operations more efficient and allowing better data collection.

“The glider provides data that help explain how temperature, salinity, and density change in space and time underwater, and the HF radar provides high resolution maps of surface currents every 20 minutes,” said Edwards. “The two systems are highly complementary, and their combination provides an unprecedented view of when, where, and why there is exchange between the shelf and deep ocean.”

According to Savidge, the study should produce a greater understanding of the forces at work at Cape Hatteras with implications across a wide range of interests from fisheries management to pollution control. Microscopic marine plants, known as phytoplankton, are a vital part of the marine ecosystem. Phytoplankton are the very base of the marine food web and they produce approximately half the oxygen in the atmosphere. In addition to tracking deep water inputs that support productivity on the shelf, Savidge said, it would is also be important to understand any processes that transport carbon-rich shelf water back to the deep ocean. When phytoplankton and the rest of the food web convert nutrients into their own biomass, water returned to the deep ocean can carry large quantities of organic carbon with it.

The knowledge gathered at Cape Hatteras will be applicable to other oceans around the world.

“Cape Hatteras is the ideal place to look at these processes that you are going to find elsewhere,” Savidge said. “You have a lot of energetic forcing and everything is concentrated in a very small space, with large variations over short distances. The idea is to understand the processes so you can model them effectively. If you can do that, you can anticipate how circulation on the shelf and exchanges with the deep ocean will respond to changes in the Gulf Stream or the wind over time.”

The project will run through March 2020. The other members of the research team are Harvey Seim and John Bane of the University of North Carolina; Ruoying He of North Carolina State University; and Robert Todd, Magdalena Andres and Glen Gawarkiewicz from Woods Hole Oceanographic Institute.

Savidge expressed special appreciation to the National Park Service and the North Carolina Department of Transportation for providing sites for the radar installations, and the University of North Carolina’s Coastal Studies Institute for help in installing them.

UGA Skidaway Institute scientists study microbial chemical warfare

In the battlefield of the microbial ocean, scientists have known for some time that certain bacteria can exude chemicals that kill single-cell marine plants, known as phytoplankton. However, the identification of these chemical compounds and the reason why bacteria are producing these lethal compounds has been challenging.

Now, University of Georgia Skidaway Institute of Oceanography scientist Elizabeth Harvey is leading a team of researchers that has received a $904,200 grant from the National Science Foundation to fund a three-year study into the mechanisms that drive bacteria-phytoplankton dynamics.

Researcher Elizabeth Harvey examines a part of her phytoplankton collection.

Understanding these dynamics is important, as phytoplankton are essential contributors to all marine life. Phytoplankton form the base of the marine food chain, and, as plants, produce approximately half of the world’s oxygen.

“Bacteria that interact with phytoplankton and cause their mortality could potentially play a large role in influencing the abundance and distribution of phytoplankton in the world ocean,” Harvey said. “We are interested in understanding this process so we can better predict fisheries health and the general health of the ocean.”

A microscopic view of a population of phytoplankton.

This project is a continuation of research conducted by Harvey and co-team leader Kristen Whalen of Haverford College when they were post-doctoral fellows at Woods Hole Oceanographic Institution. They wanted to understand how one particular bacteria species impacted phytoplankton.

“We added the bacteria to the phytoplankton and the phytoplankton died,” Harvey said. “So we became very interested in finding the mechanism that caused that mortality.”

They identified a particular compound, 2-heptyl-4-quinlone or HHQ, that was killing the phytoplankton. HHQ is well known in the medical field where it is associated with a bacterium that can cause lung infections, but it had not been seen before in the ocean. The team will conduct laboratory experiments to determine the environmental factors driving HHQ production in marine bacteria; establish a mechanism of how the chemical kills phytoplankton; and use field-based experiments to understand how HHQ influences the population dynamics of bacteria and phytoplankton.

“This project has the potential to significantly change our understanding of how bacteria and phytoplankton chemically communicate in the ocean.” Harvey said.

The project will also include a strong education component. The researchers will recruit undergraduate students, with an effort to target recruitment of traditionally under-represented groups, to participate in an intense summer learning experience with research, field-based exercises and some classroom work.

“The idea is for the students to return to their home institutions at the end of the summer, but to continue to work with us on this project,” Harvey said. “This will be a unique opportunity to offer students cross disciplinary training in ecology, chemistry, microbiology, physiology and oceanography.”

In addition to Harvey and Whalen, the research team includes David Rowley of the University of Rhode Island.

UGA Skidaway Institute associate professor cited for top research articles

University of Georgia Skidaway Institute of Oceanography associate professor Aron Stubbins is one of just a handful of researchers cited in the journal Limnology and Oceanography for authoring two of the journal’s top scientific papers over the past 60 years.OLYMPUS DIGITAL CAMERA

Limnology and Oceanography is an official publication of the Association for the Sciences of Limnology and Oceanography and is considered a premier scientific journal. In its recently published 60th anniversary issue, the journal collected and republished the 10 most cited research papers for each of the last six decades. Stubbins authored or co-authored two of those papers, one in 2008 and the other in 2010.

“It came as quite a surprise to see two articles show up on the list,” Stubbins said. “I was at a conference and wasn’t really checking my email when one of my colleagues let me know.”

The journal used the number of times a paper was cited in future studies as the yardstick to determine which papers should be included on the list. It is one commonly used method for measuring the impact of a scientist’s work.

“The list isn’t really about popularity,” Stubbins said. “It’s about usefulness. That people have found some of my work useful over the years is rewarding.”

The 2008 paper was titled “Absorption spectral slopes and slope ratios as indicators of molecular weight, source, and photobleaching of chromophoric dissolved organic matter.” The lead author was John Helms. Stubbins was a co-author along with four other scientists. The research team developed a new method for extracting new information from a relatively common and simple test of the color of dissolved organic matter.

Stubbins was the lead author, along with nine co-authors, of the second paper, “Illuminated darkness: Molecular signatures of Congo River dissolved organic matter and its photochemical alteration as revealed by ultrahigh precision mass spectrometry.” The study examined organic carbon carried to the ocean by the Congo River — after the Amazon, the second largest river in the world in terms of carbon and water flow. The research team studied how sunlight degrades organic material, including which compounds are degraded, which are not and what new compounds are created when sunlight shines on river water.

“His inclusion in this seminal volume is quite an honor for Dr. Stubbins,” UGA Skidaway Institute Interim Director Clark Alexander said. “This recognition validates what we have always known, that he is conducting groundbreaking and meaningful research that is recognized around the world.”

All 60 papers can be found at http://aslopubs.onlinelibrary.wiley.com/.

 

Teachers join UGA Skidaway Institute research cruises

JoCasta Green became a teacher after she was told as a child she couldn’t be a scientist because she was a girl. In May, the pre-K teacher from Decatur, Georgia, achieved a small piece of her childhood dream by joining a research cruise on board the University of Georgia Skidaway Institute of Oceanography’s Research Vessel Savannah. Green was one of two teachers on the overnight cruise, some of the first to participate in a cooperative program between UGA Skidaway Institute and Georgia Southern University’s Institute for Interdisciplinary STEM Education (i2STEM).

“Because I am an elementary teacher, I was afraid that maybe I shouldn’t have applied,” Green said. “However, once I got here and everyone was so interested and wanted to share, I really did learn a lot.”

Green (left) learns to set the spring-loaded bottle plugs on a conductivity-temperature-depth sensor array with the help of Natalia Lopez Figueroa from Hampton University.

JoCasta Green (right) learns how to prepare a conductivity-temperature-depth sensor array for deployment with the help of Natalia Lopez Figueroa from Hampton University.

UGA Skidaway Institute scientist Marc Frischer led the cruise with the aim to hunt, collect and study doliolids — a small gelatinous organism of great significance to the ecology and productivity of continental shelf environments around the world. Green and middle school teacher Vicki Albritton of Savannah were the only teachers on board and were able to actively participate in the research activities.

“I think giving any teacher the opportunity come to out to sea is an amazing experience,” Frischer said. “I think it’s transformative, but to have them integrated into the research, we haven’t really done that before.”

Marc Frischer chats with JoCasta Green during the cruise.

Marc Frischer chats with JoCasta Green during the cruise.

Green and Albritton participated in the deck activities. They helped launch the CTD (conductivity-temperature-depth) sensor packages mounted on heavy metal frames and deployed plankton nets that concentrated a wide variety of tiny marine creatures into a small container. The two teachers then worked with the science team in the darkened wet lab to sort through gallons of water and to isolate the doliolids they were seeking.

“I was hoping to see science in action, and I did that all day long,” Albritton said. “I got to participate and learn what was going on and take many pictures, and now I have a wealth of information to take back to the classroom.”

Albritton says an experience like the cruise raises teachers’ credibility in the classroom, because the students see the teachers going out to learn more themselves. “If I want them to be perpetual learners, then I need to demonstrate that same trait,” she said.

Although Green admitted she was nervous about the cruise initially, she credited the scientists with making her comfortable. “They were great teachers,” she said. “I understood what we were doing and why we were doing it.”

Albritton echoed Green’s thoughts and cited the graciousness of everyone she encountered on the cruise. “There wasn’t condescension or an implication that we didn’t know anything,” she said. “There was genuine respect for all of us as professionals in our fields. That was really wonderful.”

A research cruise on the 92-foot R/V Savannah will never be confused with a luxury vacation cruise. Green and Albritton agreed the food was good, but the working spaces were tight and the bunks and cabins even more so.

Green and Albritton were the second group of teachers to join an R/V Savannah research cruise through the partnership with Georgia Southern’s i2STEM program. The goal of the i2STEM program is to improve the teaching and learning of science, technology, engineering and mathematics at all levels from kindergarten through college throughout coastal Georgia.

Vicki Albritton (left) and JoCasta Green

Vicki Albritton (left) and JoCasta Green

The partnership between UGA Skidaway Institute and i2STEM is expected to grow. Five additional doliolid cruises are scheduled this year with space available for as many as four teachers on each cruise. UGA Skidaway Institute will also offer two half-day cruises this month as part of i2STEM’s summer professional development workshop for teachers.

According to Frischer, the ultimate goal of scientific research is to generate and communicate information. “Teachers are some of our most important communicators,” he said. “They communicate to the next generation, so I think it is really special to be able to bring teachers right to where the research is happening. It gives them a total perspective, not only on what we are doing, but how research works and to communicate that to their students.”

Both Green and Albritton said they would encourage their fellow teachers to take advantage of opportunities like this. “You would be crazy not to, in terms of learning and what you can bring back to the kids in your classroom,” Albritton said. “It’s an experience you will never forget.”

Molecular-level relationships key to deciphering ocean carbon

by Alan Flurry

From beach shallows to the ocean depths, vast numbers of chemical compounds work together to reduce and store atmospheric carbon in the world’s oceans.

In the past, studying the connections between ocean-borne compounds and microbes has been impractical because of the sheer complexity of each. Three University of Georgia faculty members—along with an international team of scientists—bring to the forefront technological developments that are providing scientists with the analytical tools needed to understand these molecular-level relationships.

Their perspective article appears March 7 in the Proceedings of the National Academy of Sciences. It focuses on dissolved organic matter, or DOM, in the world’s oceans as a central carbon reservoir in the current and future global carbon cycle.

“Dissolved organic carbon is an amazing and confounding molecular soup,” said Aron Stubbins, co-author and associate professor of marine sciences at UGA housed at the Skidaway Institute of Oceanography in Savannah. “It sits at the center of the ocean carbon cycle, directing the energy flow from the tiny plants of the sea, phytoplankton, to ocean bacteria. Though around a quarter of all the sunlight trapped by plants each year passes through dissolved organic carbon, we know very little about the chemistry of the molecules or the biology of the bacterial players involved.”

The carbon the microbes process is stored in seawater in the form of tens of thousands of different dissolved organic compounds.

Researchers thought they had a handle on how some aspects of the process works, but “a number of new studies have now fundamentally changed our understanding of the ocean carbon cycle,” said the paper’s lead author Mary Ann Moran, Distinguished Research Professor at UGA.

In the context of methodological and technological innovations, the researchers examine several questions that illustrate how new tools—particularly innovations in analytical chemistry, microbiology and informatics—are transforming the field.

From how different major elements have cycles linked though marine dissolved organic matter to how and why refractory organic matter persists for thousands of years in the deep ocean to the number of metabolic pathways necessary for microbial transformation, the article infers a scale of enhanced and expanded understanding of complex processes that was previously impractical.

The perspective article, “Deciphering Ocean Carbon in a Changing World,” was shaped in discussions at a 2014 workshop supported by the Gordon and Betty Moore Foundation and Microsoft Research Corporation. Moran’s research has been supported by the Gordon and Betty Moore Foundation’s Marine Microbiology Initiative.

Co-authors on the paper include UGA’s Patricia Medeiros, assistant professor in the department of marine sciences. Others involved are with the Woods Hole Oceanographic Institute; the Scripps Institute of Oceanography and the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego; University of Tennessee, Knoxville; Oregon State University; Columbia University; The Pacific Northwest National Laboratory, Richland Washington; the University of Washington; University of Oldenburg, Germany; Sorbonne Universités; and the University of Chicago.