Tag Archives: science

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.”

Savannah Science Seminar students learn about Skidaway Institute research

A group of local high school students got an up-close look at oceanography through a special program at UGA’s Skidaway Institute of Oceanography. The students were participants in the Savannah Science Seminar, a nine-month-long program designed to promote an understanding and appreciation for science through informative, participatory presentations and hands-on workshops in the fields of engineering, technology, mathematics and the medicine.

Julia Diaz profiles some of her research.

Their March 27 visit to Skidaway Institute exposed them to some of the topics studied and techniques used in marine research.

Skidaway Institute scientist Julia Diaz organized the evening’s program. After an introductory talk by researcher Jim Sanders, the students were split into three groups that rotated among three science stations.

Physical oceanographer Catherine Edwards explained the workings of autonomous underwater vehicles.

Catherine Edwards describes an AUV.

Graduate students Patrick Duffy and Sean Anderson demonstrated the new LIME imaging lab.

Patrick Duffy (2nd from right) and Sean Anderson (far right) introduce the students to cutting edge microbial imaging instruments.

Diaz and grad student Sydney Plummer discussed eutrophication and phytoplankton blooms.

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.

Skidaway Institute adds to fleet

UGA Skidaway Institute has added its newest and smallest research vessel to its fleet. Researcher Clark Alexander’s team is in the process of configuring a new shallow water survey boat to enhance its capabilities for collecting high-resolution bathymetric data. new-boat-1-w

Hydrographic surveys in shallow environments present challenging logistical situations.  The new Hydrographic Survey Launch will greatly extend the range of tides and conditions available for survey missions. The launch is 10 feet long and will be equipped with a Knudsen Mini-Sounder single-beam sonar, a dual head GNSS GPS system, an inertial motion sensor  and a waterproof touchscreen computer.

UGA Skidaway Institute develops cutting-edge microbial imaging laboratory

A team of researchers from the University of Georgia Skidaway Institute of Oceanography has received a $226,557 grant from the National Science Foundation to acquire state-of-the-art imaging equipment to investigate microorganisms from the tiniest viruses to larger zooplankton. The equipment will be housed in UGA Skidaway Institute’s new Laboratory for Imaging Microbial Ecology, or LIME.

Researcher Elizabeth Harvey leads the research team that also includes UGA Skidaway Institute scientists Julia Diaz, Marc Frischer, James Nelson and James Sanders.

UGA Skidaway Institute researchers Tina Walters, Marc Frischer and Karrie Bulski practice running zooplankton samples on the FlowCam, a new instrument that is part of LIME

UGA Skidaway Institute researchers Tina Walters, Marc Frischer and Karrie Bulski practice running zooplankton samples on the FlowCam, a new instrument that is part of LIME

The equipment will improve Skidaway Institute’s capability to conduct field and laboratory experiments by automating many viewing methods.

“Anyone who uses a microscope will tell you that it is both tedious and time consuming,” Harvey said. “This equipment will allow us to enumerate and analyze microbes and other planktonic organisms much faster, and will allow us to do more large-scale projects than we could in the past.”

Microscopic phytoplankton photogaphed in the LIME.

Microscopic phytoplankton photogaphed in the LIME.

Much of the equipment will also have imaging capability so researchers will be able to do more detailed measurements on the size and shape of the tiny organisms and how that might relate to the health of an ecosystem.

Marine microbes are an essential component of all marine ecosystems and they play central roles in mediating biogeochemical cycling and food web structure.

“They are the things that drive all other processes in the ocean,” Harvey said. “They play a really important role in the way nutrients, oxygen and carbon are cycled through the ocean. We care a lot about those processes because they impact our climate, fisheries and the ocean’s overall health.”

The benefits of LIME will be shared beyond Skidaway Institute’s science team. Harvey envisions it as a regional center for microbial imaging, available to any other researchers who need the capability.

“Anyone is welcome to come here and get trained to use them,” she said. “They just need to contact me and we can make arrangements.”

Some of the equipment is already in place, while other pieces have not been delivered. Harvey anticipates all the equipment being functional by mid-2017.