A research team from the University of Georgia Skidaway Institute of Oceanography has completed the first high-resolution, bathymetric (bottom-depth) survey of Wassaw Sound in Chatham County.
Led by Skidaway Institute scientist Clark Alexander, the team produced a detailed picture of the bottom of Wassaw Sound, the Wilmington River and other connected waterways. The yearlong project was developed in conjunction with the Georgia Department of Natural Resources.
The survey provides detailed information about the depth and character of the sound’s bottom. This information will be useful to boaters, but boating safety was not the primary aim of the project. The primary objective was to map bottom habitats for fisheries managers. DNR conducts fish surveys in Georgia sounds, but, according to Alexander, they have limited knowledge of what the bottom is like. “One of the products we developed is an extrapolated bottom character map,” Alexander said. “This describes what the bottom grain size is like throughout the sound. Is it coarse, or shelly or muddy? This is very important in terms of what kind of habitat there is for marine life.”
A second goal was to provide detailed bathymetric data to incorporate into computer models that predict storm surge flooding caused by hurricanes and other major storms. Agencies like the United States Army Corps of Engineers, the Federal Emergency Management Agency and the National Oceanographic and Atmospheric Administration use mathematical models to predict anticipated storm inundation and flooding for specific coastal areas. A key factor in an accurate modeling exercise is the bathymetry of the coastal waters.
“You need to know how the water will pile up, how it will be diverted and how it will be affected by the bottom morphology,” Alexander said. “Since we have a gently dipping coastal plain, storm inundation can reach far inland. It is important to get it as right as we can so the models will provide us with a better estimate of where storm inundation and flooding will occur.”
Funded by an $80,000 Coastal Incentive Grant from DNR, Alexander and his research team, consisting of Mike Robinson and Claudia Venherm, used a cutting-edge interferometric side-scan sonar system to collect bathymetry data. The sonar transmitter/receiver was attached to a pole and lowered into the water from Skidaway Institute’s 28-foot Research Vessel Jack Blanton. Unlike a conventional fishfinder, which uses a single pinger to measure depth under a boat, the Edgetech 4600 sonar array uses fan-shaped sonar beams to both determine water depth and bottom reflectivity, which identifies sediment type, rocky outcroppings and bedforms, in a swath across the boat’s direction of travel.
The actual process of surveying the sound involved long hours of slowly driving the boat back and forth on long parallel tracks. On each leg, the sonar produced a long, narrow strip indicating the depth and character of the sound bottom. Using high-resolution Global Positioning System data that pinpointed the boat’s exact location, the system assembled the digital strips of data into a complete picture of the survey area.
All the other sounds on the Georgia coast were mapped in 1933, but for some reason data from that time period for Wassaw Sound was unavailable. When the team began this project, they believed they were conducting the first survey of the sound. However, just as the researchers were finishing the project, NOAA released data from a 1994 single-beam survey that had been conducted in advance of the 1996 Olympic yachting races that were held in and near Wassaw Sound.
“This worked out very well for our project, because we are able to compare the differences between the two surveys conducted 20 years apart,” Alexander said. “We see areas that have accumulated sediment by more than 2 meters, and we also see areas that have eroded more than 2 meters since 1994. Channels have shifted and bars have grown or been destroyed.”
Because of advances in technology, the current survey is significantly richer in detail than the one conducted in 1994. “We can zoom down to a square 25 centimeters (less than a foot) on a side and know the bottom depth,” Alexander said.
The survey produced a number of findings that were surprising. The intersection of Turner Creek and the Wilmington River is a deep, busy waterway. Although most of the area is deep, the survey revealed several pinnacles sticking up 20 feet off the bottom. “They are round and somewhat flat, almost like underwater mesas,” Alexander said.
The researchers determined that the deepest place mapped in the study area was a very steep-sided hole, 23 meters deep, in the Half Moon River where it is joined by a smaller tidal creek. They also found several sunken barges and other vessels.
The survey data set is available to the public on the Georgia Coastal Hazards Portal at http://gchp.skio.usg.edu/. Alexander warns that while boaters should find the survey interesting, the information is intended for habitat research and storm surge modeling, not for navigation. “Because the bottom of Wassaw Sound is always shifting and changing, as our survey showed, don’t rely on the data for safe navigation,” he cautioned.
Alexander has already received a grant for an additional survey, this time of Ossabaw Sound, the next sound south of Wassaw Sound. He expects work to begin on that survey in early 2015.
The Skidaway Institute of Oceanography is a research unit of the University of Georgia located on Skidaway Island near Savannah. The mission of the institute is to provide the state of Georgia with a nationally and internationally recognized center of excellence in marine science through research and education.
University of Georgia Skidaway Institute of Oceanography scientist Catherine Edwards is part of a research team that has received an $18.8 million grant to continue studies of natural oil seeps and track the impacts of the BP/Deepwater Horizon oil spill in the Gulf of Mexico ecosystem.
Known as ECOGIG-2 or “Ecosystem Impacts of Oil and Gas Inputs to the Gulf,” the project is a collaborative, multi-institutional effort involving biological, chemical, geological and chemical oceanographers led by the University of Georgia’s Samantha Joye. The research team has worked in the Gulf since the weeks following the 2010 Macondo well blowout.
The three-year, $18.8 million ECOGIG-2 program was funded by the Gulf of Mexico Research Initiative, or GoMRI.
“Our goal is to better understand the processes that have affected the oil spill since 2010,” Edwards said. “How the droplets were dispersed? Where the oil went? How it was taken up by small microbes and also the effects on animals further up the food chain?”
Edwards’ role in the project is to use autonomous underwater vehicles, also called “gliders,” to collect data on conditions around the spill site. Equipped with sensors to measure characteristics such as depth, water temperature, salinity and density, the gliders can cruise the submarine environment for weeks at a time, collecting data and transmitting it back to a ship or a shore station.
“We want to understand the ocean currents—how they change over time and how they change in depth,” Edwards said. “Surface measurements give us a two-dimensional picture of the ocean. Glider data in the vertical provides more valuable information for more fully understanding ocean currents and how they arise.”
The gliders will operate both in conjunction with shipboard instruments and also independently. One advantage of using the gliders is they can operate during storms and rough weather, when it may not be possible to use ships. Edwards said shipboard work doesn’t always give a full picture of ocean dynamics simply by the fact that they can only go out when the weather is reasonably clear.
When working in conjunction with research ships, the gliders can provide additional observations, significantly improving the quality of the data set. The gliders also report dissolved oxygen concentrations and optical measurements of chlorophyll and organic matter, and may also be used as a test vehicle for new instruments in development.
Edwards will use “GENIoS,” a new software package, to help navigate the gliders. GENIoS uses high-resolution forecast models of wind and ocean currents, along with information from the glider itself, to calculate the optimal path for the gliders. This will improve the quality of the scientific data collected.
GENIoS is a collaboration among Edwards, Fumin Zhang from the Georgia Institute of Technology and their two Georgia Tech Ph.D. students, Dongsik Chang and Sungjin Cho. GENIos has been tested for more than 210 glider-days on the continental shelf off Georgia and South Carolina. This experiment will be its first test in the Gulf of Mexico.
Edwards also hopes to use this project to test the gliders as platforms for new, experimental sensors developed by other members of the ECOGIG-2 team.
Others involved in ECOGIG-2 include UGA marine sciences faculty Christof Meile, Renato Castelao and Catherine Edwards as well as Annalisa Bracco and Joe Montoya of Georgia Tech.
For additional information, contact Catherine Edwards at (912) 598-2471 or email@example.com.
Educators and scientists from the University of Georgia Skidaway Institute of Oceanography and the UGA Marine Extension Service have developed a novel education program based on ocean robots to spark an interest in science and mathematics in middle and high school students. The team invented a board game that lets students explore different strategies for navigating autonomous underwater vehicles, called AUVs or gliders, through the ocean.
The program, “Choose Your Own Adventure,” capitalizes on Skidaway Institute’s expertise with AUVs and MAREX’s extensive history of marine education. Skidaway Institute scientist and UGA faculty member Catherine Edwards and MAREX faculty members Mary Sweeney-Reeves and Mare Timmons are directing the one-year project, which demonstrates the decision-making process in “driving” gliders.
Gliders are untethered, torpedo-shaped vehicles that are launched into the ocean to collect data as they move through the water. They glide up and down by adjusting their buoyancy and pitch. Gliders can remain on a mission for weeks at a time, equipped with sensors and recorders to collect observations of temperature, salinity, dissolved oxygen, and other biological and physical conditions, even under the roughest weather. Every four to six hours over their mission, they surface and connect to servers on land to report their position and vehicle and mission information. They also can send data back to shore or receive new instructions from pilots anywhere in the world. Skidaway Institute’s glider, nicknamed “Modena,” has been used in several recent projects, including “Gliderpalooza,” a simultaneous, cooperative launch of dozens of AUVs from different institutions in 2013 and again in 2014.
“Gliders are education-friendly, but the existing outreach activities are stale,” Edwards said. “We are developing the next generation of AUV outreach programs by combining cutting-edge, interdisciplinary research with educational activities and strong STEM components.”
The AUV activity/game is a part of an outreach program targeting mostly middle school students and it highlights the problem of working with the strong tides that are characteristic of the Georgia coast. A big issue in operating gliders is developing a guidance and navigation system that will function well in strong currents. The fast-moving Gulf Stream, located roughly 100 miles off the Georgia beaches, also introduces navigation problems.
“Although the AUVs have Global Positioning Systems and can be programmed to travel a set course, tidal and Gulf Stream currents can exceed the glider’s forward speed, which can take the instrument off course and keep us from collecting data where we need it,” Edwards said. “By estimating forecasts of these currents in advance, our software system can predict the best possible route for the glider to take, which helps collect the best possible data.”
On the education side, the predictability of tides makes the proposed program highly intuitive and education-friendly. The activity/game incorporates student role-playing as an AUV maneuvers through a playing field of vector currents on a game board. The student decides how many of his or her moves to spend fighting the current and how many to spend moving toward the finish line. Successful arrival at the destination depends on how the individual pilot responds to currents en route.
Activities depend on grade level, so middle school students have different objectives than those in high school. However, all the activities address the direction and speed the AUV travels to a destination. The AUV direction and speed will depend on the sea state, such as strong currents, storms or high winds.
Teachers April Meeks and Ben Wells from Oglethorpe Academy have offered their classes as a test-bed for the game. The two have worked closely with the team to integrate classroom concepts into the game and guide discussions about strategy based on the math. Since the activities are multidisciplinary, the teachers’ expertise in building a math curriculum has been valuable as the team integrates concepts of marine science, math and engineering into classroom activities. Rolling giant dice is a fun activity that attracts the students—everyone wants to roll the dice. So far, the feedback has been very positive.
“The students really seem to love it,” Sweeney-Reeves said. “More importantly, they are making the connection between the game and science, and learning.
“It took a period of time for some students to understand the concept but after starting the second round, they had the game/activity figured out. The excitement peaked at Oglethorpe Middle School when Mr. Wells played against the students and we really saw the competition heat up.”
Edwards added, “We knew we had a hit when we saw students jump up in celebration when the currents were favorable and pout when they were blown off course.”
The team demonstrated the game at the campus’s annual open house, Skidaway Marine Science Day, in late October, with a life-sized version of the board game with giant dice. Over 120 students played the game, racing against each other as they explored different strategies to win in three- to five-person heats. Sweeney-Reeves and Timmons also rolled out the game for educators at the Georgia Association of Marine Educators annual conference on Tybee Island earlier this month.
“The conference attendees were excited to use the giant dice to roll and hedge their bets on where they could navigate to the finish line,” Timmons said. “This is much like how the AUV is programmed to reach its sampling assignment in the ocean.”
Timmons said the teachers at the conference laughed as they saw the big game board spread out on the sidewalk. “Towards the end as teachers were close to the finish line they shouted, ‘right!’, mentally trying to encourage the roll of the die to their advantage.”
Timmons and Sweeney-Reeves think the game has real-life applications and hope the students can use the concepts they learn in the classroom for swimming in our own local waters. The next step is to expand the classroom demonstrations to Coastal Middle School in Chatham County and Richmond Hill Middle School.
The activities allow students to develop analytical skills in a program that will be compliant with Next Generation Science Standards for the 21st Century in the common core state curriculum.
“We hope this one-year program will serve as a springboard for future funding and continued joint outreach by Skidaway Institute and Marine Extension,” Edwards said. “We’d love to develop computer games and apps for tablets and mobile phones that let students fly gliders through even more realistic scenarios based on the measurements we collect in real time.”
The program is being funded through a joint grant from Skidaway Institute, UGA Office of Public Service and Outreach, and the UGA President’s Venture Fund. The UGA President’s Venture Fund is intended to assist with significant funding challenges or opportunities. The fund also supports small programs and projects in amounts typically ranging from $500 to $5,000.
The Skidaway Institute of Oceanography is a research unit of the University of Georgia located on Skidaway Island. Its mission is to provide a nationally and internationally recognized center of excellence in marine science through research and education. The UGA Marine Extension Service is a unit of the Office of Public Service and Outreach.
For additional information, contact Catherine Edwards at 912-598-2471 or firstname.lastname@example.org; Mary Sweeney-Reeves at 912-598-2350 or email@example.com; or Maryellen Timmons at 912-598-2353 or firstname.lastname@example.org.
Exploring the ocean with underwater robots will be the focus of an Evening @ Skidaway at the UGA Skidaway Institute of Oceanography on Thursday, November 13. The program will held in the McGowan Library at the University of Georgia Skidaway Institute of Oceanography, beginning with a reception at 6:30 p.m. to be followed by the lecture program at 7:15 p.m.
UGA Skidaway Institute professor Catherine Edwards will discuss her adventures and misadventures in the exciting field of underwater robots. Shaped like a six-foot long torpedo with stubby plastic wings, these autonomous underwater vehicles, or gliders, can be packed with sensors and are set lose to cruise the submarine environment for weeks on end. They produce amazing results, and sometimes face unusual and unexpected perils.
An “Evening @ Skidaway” is sponsored by the Skidaway Institute of Oceanography and the Associates of Skidaway Institute.
The program is open to the public, and admission is free.
For additional information, visit www.skio.uga.edu or call (912) 598-2325.
SkIO Seminar: Probing the photochemical reactivity of oceanic dissolved organic carbon
Leanne Powers, Ph.D., Postdoctoral Scholar, SkIO
Skidaway Institute of Oceanography, John F. McGowan Library Auditorium, Savannah, GA
After 20 years of research in aquatic photochemistry, there remains a need to identify and constrain many photochemical reactions involving colored dissolved organic matter (CDOM). In an effort to improve our quantitative understanding of photochemistry’s significance in biogeochemical cycles, the basic approach uses laboratory and field studies in diverse marine systems to examine the photochemical efficiency and reaction rates for carbon monoxide (CO), carbon dioxide (CO2), superoxide (O2-) and hydrogen peroxide (H2O2). Input of these results into ocean color-based models then allows for estimation of photochemical rates on regional and global scales.
Direct photo-oxidation of dissolved organic carbon (DOC) to CO2 and CO is a significant, albeit poorly constrained, DOC removal mechanism. Working in the Northern Gulf of Mexico, we amassed the largest cohesive CO apparent quantum yield (AQY) data set for any marine region (n=99; 18 paired with CO2), defining distinct inshore and offshore AQY spectra for improved regional photochemical rate models. Analytical limitations for determining CO2 AQY spectra forced the use of ill-defined coastal CO2:CO ratios (~6−66) for blue water CO2 calculations, highlighting the need for new direct methods or better proxies to quantify CO2 photochemistry in marine waters.
Significant photochemical removal of biologically refractory DOC (RDOC), well-mixed in the ocean but isolated at depth, is not compatible with its 14C age. Reevaluation of RDOC photochemical reactivity using paired O2- and H2O2 photoproduction studies for abyssal Gulf of Alaska samples showed declining O2- steady-state concentrations during long-term exposure, with little or no H2O2 accumulation past ~6−12 hours. This is consistent with a loss of O2- source, a shift to oxidative pathways for O2‑ decay, and a lack of long-term photochemical reactivity for RDOC.
Because H2O2 formation is a thermal reaction involving O2-, blending remotely sensed sea surface temperature and color allowed correction of H2O2 AQY spectra and production of the first global H2O2 and O2‑ photoproduction rate maps from remotely sensed data. Further analysis of paired H2O2 and CO2 photoproduction experiments indicated that H2O2 is a far better proxy for CO2 photoproduction than CO (CO2:H2O2 ratio = 6).
SkIO Seminar: Consortium for Ocean Leadership Distinguished Lecturer Series, Buried alive: Life beneath the seafloor
Dr. Beth Orcutt, Bigelow Laboratory for Ocean Sciences
Skidaway Institute of Oceanography, John F. McGowan Library Auditorium, Savannah, GA
Roughly seventy percent of the Earth’s surface is covered by marine sediment and oceanic crust. Microbes – bacteria, archaea, tiny eukaryotes, and viruses – are major players in these environments, cycling elements and eating carbon. The marine subsurface is a vast reservoir of life “buried alive” on Earth, yet we don’t fully understand how all of the microbes get their energy to grow, or the full impact of their activity on chemical cycling. Dr. Orcutt has developed novel incubation devices that are deployed in subseafloor observatories to track microbial growth and will present an overview of some of the exciting microbiological, geochemical, and ocean exploration research being conducted within the International Ocean Discovery Program and other deep-sea science programs.
Dr. Orcutt has been involved in IODP Expeditions 327 and 336 to explore for life in deep sediment and rocks.
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