Posts Tagged ‘Salt marsh’

Video — UGA Skidaway Institute scientists complete sea level study on Georgia coast

February 25, 2016

Sea level is projected to rise at least one meter by 2100. Where will that water go and how will it change the Georgia coastal ecosystem? University of Georgia Skidaway Institute of Oceanography scientist Clark Alexander and Georgia Southern University researcher Christine Hladik are attempting to answer those questions.

https://youtu.be/vNFrxb4cytU

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An early morning TV story at UGA Skidaway Institute

September 22, 2015

WSAV TV and reporter Martin Staunton aired a story t his morning on Dr. Clark Alexander’s study on sea level rise on the Georgia coast.

http://wsav.com/2015/09/22/rising-sea-level-may-change-georgias-marshes/

Scientists work to predict 22nd century look of the Georgia coast

August 27, 2015

University of Georgia Skidaway Institute of Oceanography scientist Clark Alexander is working on a project to predict how the Georgia coast—characterized by a complex system of barrier islands, salt marshes, estuaries, tidal creeks and rivers—may look 25, 50 and 100 years from now. As sea level rises over the next century, that picture is changing.

Predictions of sea level rise over the next century vary from the current rate of roughly 30 centimeters—about a foot—to as much as two meters—about 6 feet. Although scientists disagree on the ultimate height of the rise, they all agree that salty water is moving inland and will continue to do so for the foreseeable future, Alexander said. Here on the Georgia coast, islands will become smaller or disappear entirely; salt marshes will be inundated by the rising waters and migrate towards the uplands; and some low-lying uplands will become salt marshes.

To predict the extent of these changes, scientists are using the predictive Sea Level Affecting Marshes Model, or SLAMM, which was originally developed for the U.S. Fish and Wildlife Service.

SLAMM predicts the effects of future sea level rise based on two key inputs: an elevation mapping of the coastal zone and salinity profiles up the rivers and waterways. Salinity and elevation are two key factors that determine the type of plants, and thus habitat, that will be present at any particular location.

“As sea level rises, the fresh water in rivers will be pushed further upstream,” Alexander said. “The brackish and salty water will also move up, and the salt marshes will expand.”

Researcher Mike Robinson adjusts the salinity monitoring equipment while LeAnn DeLeo drives the boat.

Researcher Mike Robinson adjusts the salinity monitoring equipment while LeAnn DeLeo drives the boat.

Funded by a Coastal Incentive Grant from the Georgia Department of Natural Resources Coastal Management Program, Alexander and his team have been studying the five key river systems along the coast and numerous salt marsh estuaries. Salinity along the coast is dominantly affected by river discharge into the estuaries, so the team has been conducting its surveys during both winter—high river flow—and the summer—low river flow—conditions.

“We start at the mouth of a river about an hour before high tide and then we follow that high tide up the river, mapping the surface salinity along the way,” Alexander said. “We find the maximum inshore intrusion of salinity at high tide during a spring tide. That is the location that defines the boundary between the brackish marshes and the freshwater marshes.”

In addition to tracking surface salinity, the researchers also stop periodically and measure the salinity throughout the water column to determine if what they measure at the surface is similar to what is present near the bottom. They lower a device that measures the water conductivity (which is related to salinity), temperature and depth from the surface to the bottom. Also equipped with GPS capability, the device automatically captures the location of every water column profile.

Researcher LeeAnn DeLeo lowers the sensor to measure conductivity, temperature and depth from the surface to the bottom.

Researcher LeeAnn DeLeo lowers the sensor to measure conductivity, temperature and depth from the surface to the bottom.

In many coastal regions, denser, saltier water tends to sink to the bottom and the lighter, fresh water remains near the surface. However, because of the energy produced by Georgia’s wide tidal range, the team found that most of the water on the Georgia coast is well mixed and doesn’t show up as layers.

The second part of the project is to fine-tune existing elevation data. Scientists have an extensive set of elevation information from airplane-mounted Light Detection And Ranging systems. LIDAR is usually very accurate, except in marshes, because it cannot see through the vegetation to the actual ground surface.

“You might be off by 30 centimeters or more, and in a low-lying, flat area like our coastal zone, that can make a big difference in predicting where the water will flood,” Alexander said.

The Skidaway Institute team is working with Georgia Southern University scientist Christine Hladik on a fix. By comparing LIDAR data with the true elevation in a particular area, Hladik observed that the LIDAR error varied according to the type of plants growing there. For example, if the area contained the dense, tall spartina, the error was large and, on average, a consistent number of centimeters. If the region was covered with a different, less-dense-growing salt marsh plant, like short spartina, the error was smaller but also consistent.

“She discovered that if you know what type of vegetation is covering a section of marshland, you can plug in the correction and come back with an accurate measure of the elevation,” Alexander said.

The research team observed the vegetation and measured the true ground level at 400 randomly selected points throughout coastal brackish and salt marshes in Georgia. That information and knowledge of plant types is being used to correct the existing marsh elevations.

The research team will complete one more set of river surveys before the project ends in September. Alexander hopes to obtain continued funding to use this newly acquired elevation and salinity data in a fresh SLAMM model run for the Georgia coast, using all the high-resolution data developed in this project.

“We should be able to look out as much as 100 years in the future and see where the different wetlands will be by then,” he said. “That way we can plan for marsh sustainability, retreat and sea level rise.”

UGA study finds high marine debris, need for standardized reporting along Georgia coast

February 3, 2015

Skidaway Island, Ga. – University of Georgia researchers are hoping to find a consistent way to record the marine debris—particularly pieces of plastic—crowding Georgia’s beaches as part of an effort to find a solution for the growing problem.

Marine debris has been washing up on Georgia beaches and uninhabited islands for years. Combatting the issue starts with figuring out how big it is, and a new two-part study from the UGA Skidaway Institute of Oceanography and Marine Extension published online in the Marine Pollution Bulletin finds that marine debris reporting can improve if it becomes standardized.

The problem right now is this: A volunteer group goes out and records the weight or volume of the marine debris collected. However, volunteers don’t often record the specific square feet measured or the contents of the debris. Due to a lack of report standardization, researchers often can’t compare the marine debris, especially plastic fragments, reported by different groups.

A sample of marine debris collected along the Georgia coast sits on a table at the UGA Skidaway Institute of Oceanography.

A sample of marine debris collected along the Georgia coast sits on a table at the UGA Skidaway Institute of Oceanography.

“We’ve seen plastic usage go up dramatically,” said study co-author Dodie Sanders, a marine educator and outreach coordinator for UGA Marine Extension, a unit of the Office of Public Service and Outreach. “It’s an important 21st century global issue. We need to learn more to better understand the issues of marine debris.”

The study’s lead author Richard F. Lee, professor emeritus with the UGA Skidaway Institute of Oceanography, agrees.

“Plastic debris is created on land and then it goes into rivers, flows into the ocean and washes up on land,” he said. “We’ve found that plastic debris ends up not only on populated beaches, but on inaccessible islands as well. We’ve found plastic everywhere on the coast.”

The first part of the study gathered debris from 20 sites along Georgia’s coast, including Tybee, Cumberland and Ossabaw islands. The debris was reported from volunteer organizations like Clean Coast, which hold monthly beach and marsh cleanups in Georgia.

Participants in a July 2014 teacher's workshop focusing on marine debris sift through the sands of Tybee Island in search of microplastic particles.

Participants in a July 2014 teacher’s workshop focusing on marine debris sift through the sands of Tybee Island in search of microplastic particles.

“The volunteer groups reported the weight of the debris, though we didn’t know the exact amount of plastic,” Lee said. “Based off the volunteer information we received, we did a follow-up study to more precisely measure the marine debris in a fixed location and period of time.”

The total collected debris ranged from 180 to 1,000 kilograms. The levels of plastic debris differed at each site over the course of the study, though plastic was consistently among the mix. Found plastic included plastic bottles, wrappers, food utensils and fragments of fishing gear.

Sanders spearheaded the second part of the study, where she and students collected plastic debris from Skidaway and Wassaw islands over a period of two years.

“While Dr. Lee did data analysis, I did some of the field work,” Sanders said. “We picked the two islands in the second part of the study because they were accessible sites where Marine Extension often takes students for marine education.”

For the fieldwork, Sanders and students visited the islands each month. They took inventory of what kinds of plastics were on specific areas of the coast.

“On about a monthly basis, I would take students to learn about debris and tally all the items on the islands,” Sanders said. “We took areas of 200 meters by 40 meters and recorded the items found. We also used GPS units to mark what areas we had done.”

The students, many of them in middle and high school, came from all over Georgia to assist. As part of Marine Extension, Sanders regularly teaches visiting students about marine life. When students volunteered to clean up, she tried to emphasize the issues surrounding debris.

“The bulk of the plastic comes from land,” Sanders said. “When people think of marine debris, they think of the ocean. I try to emphasize watershed concepts—what happens upstream ultimately gets downstream.”

“It can take years for plastic to degrade,” Lee said, adding, “80 percent of the plastic found at Wassaw turned out to be fragments. The fragments then spread and can have a number of environmental effects.”

Sanders says that since plastic debris is everywhere on the coast, it has to be addressed and reported efficiently to reduce its effects.

“There are proactive and reactive approaches to the issues of marine debris, and both are important,” she said. “We’ve been reactive so far by picking up debris. The proactive approach is our role in educating the public and researching the negative impacts of marine debris.”

The study was supported by the Georgia Department of Natural Resources Coastal Incentive Grant, NOAA Southeast Atlantic Marine Debris Initiative and the NOAA Marine Debris Program.

The full article on “The amount and accumulation rate of plastic debris on marshes and beaches on the Georgia coast” is available at www.sciencedirect.com/science/article/pii/S0025326X14008200#.

 

26 Hours on the Marsh — November edition

November 6, 2014

Associate Professor Aron Stubbins led a 26 hour sampling program on the marsh. The team, including Thais Bittar, Robert Spencer, Zachary Tait, Megan Thompson, Alison Buchan, and Drew Steen, spent the day and night monitoring a day in the life of the microbes, gases and organic carbon molecules that form the biogeochemical milieu of the marsh. This work is part of two National Science Foundation projects involving professors and students from Skidaway Institute of Oceanography, University of Tennessee – Knoxville, and Florida State University.

Cutting edge techniques are being employed to watch the marsh creek in real time over 18 months. The sampling event shown in the time lapse video is the fall rendition of four seasonal sampling events that are recording the daily life of the creek. Manual sampling is required so that we can collect live bacteria and gas (such as carbon dioxide) samples that need to be processed by hand, immediately upon collection. The bacteria collected are being genetically characterized, so we know who was in the creek at different times of day (DNA). Then we will also determine which genes were active (RNA). This tells us what the bacteria present in the marsh were doing throughout the day.

We also record the changes in dissolved organic carbon throughout the day. Dissolved organic carbon is a major part of the global carbon cycle and so understanding its cycling is important with respect to understanding how natural carbon cycling responds to and plays a role in climate change. For the microbes in the creek, the dissolved organic carbon (DOC) is food. So by looking at which bacteria are there (DNA), what they are doing (RNA), and what types of food is present (DOC), we hope to gain a more complete understanding of the miniature world within every drop of creek water. The daily routines of these tiny bacteria and dissolved organic molecules shape the marsh ecosystem and play important roles in determining the current and future climate of our planet.

UGA Skidaway Institute researchers complete ‘26 Hours on the Marsh’

July 30, 2014

Pitching a tent in the woods and fighting off mosquitos may not sound like logistics of a typical oceanography experiment, but that is how researchers at the University of Georgia Skidaway Institute of Oceanography completed an intensive, round-the-clock sampling regimen this month. The project, dubbed “26 Hours on the Marsh” was designed to investigate how salt marshes function and interact with their surrounding environment—specifically how bacteria consume and process carbon in the marsh.

The team set up a sampling station and an outdoor laboratory on a bluff overlooking the Groves Creek salt marsh on the UGA Skidaway Institute campus. The scientists collected and processed water samples from the salt marsh every two hours, beginning at 11 a.m. on July 16 and running through 1 p.m. July 17. By conducting the tests for a continuous 26 hours, the team can compare the samples collected during the day with those collected at night, as well as through two full tidal cycles.

The UGA Skidaway Institute team processes water samples at their outdoor laboratory. (l-r) Megan Thompson, John DeRosa (UGA Intern), Zachary Tait and Dylan Munn (UGA Intern.)

The UGA Skidaway Institute team processes water samples at their outdoor laboratory. (l-r) Megan Thompson, John DeRosa (UGA Intern), Zachary Tait and Dylan Munn (UGA Intern.)

“We wanted to be able to compare not only what is happening to the carbon throughout the tidal cycle, but also what the microbes are doing at high and low tides and also during the day and night,” said Zachary Tait, a UGA Skidaway Institute research technician. “So we had to have two high tides and two low tides and a day and night for each. That works out to about 26 hours.”

The research team ran more than 30 different tests on each sample. The samples will provide data to several ongoing research projects. A research team from the University of Tennessee also participated in the sampling program. Their primary focus was to identify the bacterial population using DNA and RNA analysis.

This sampling project is one of many the researchers conduct during the year. They use an automatic sampling system for most of the other activities. The automatic system collects a liter of water every two hours, and holds it to be collected and processed at the end of the 26-hour cycle. The team could not use the auto sampler this time for several reasons; the scientists needed to collect much more water in each sample than the auto sampler could handle and the auto sampler tends to produce bubbles in the water, so it is not effective for measuring dissolved gasses.

Megan Thompson supervises Dan Barrett (l) and John DeRosa, both UGA interns, as they process samples in a UGA Skidaway Institute laboratory.

Megan Thompson supervises Dan Barrett (l) and John DeRosa, both UGA interns, as they process samples in a UGA Skidaway Institute laboratory.

“The UT scientists wanted to conduct enzyme analysis as well as RNA and DNA tests on the samples, and for those, the samples must be very fresh,” said Megan Thompson, a UGA Skidaway Institute research technician. “You can’t just go out and pick them up the next day.”

About a dozen scientists and students were involved in the project, including Thompson, Tait, a group of undergraduate students completing summer internships at UGA’s Skidaway Institute and a similar group from UT. They split their time between the tent and outdoor laboratory on a bluff overlooking Groves Creek, and the UGA Skidaway Institute laboratories a mile away.

“It was an interesting experience, and I think it went very well,” said Thompson. “However, when we wrapped it up, we were all ready to just go home and sleep.”

“26 Hours on the Marsh” is supported by two grants from the National Science Foundation, totaling $1.7 million that represent larger, three-year, multi-institutional and multi-disciplinary research projects into salt marsh activity. These projects bring together faculty, students and staff from UGA’s Skidaway Institute, UT and Woods Hole Research Center. UGA Skidaway Institute scientists include principal investigator Jay Brandes; chemical oceanographers Aron Stubbins and Bill Savidge; physical oceanographers Dana Savidge, Catherine Edwards and Jack Blanton; and geologist Clark Alexander. Additional investigators include microbial ecologist Alison Buchan and chemical oceanographer Drew Steen, both from UT; as well as geochemist Robert Spencer from WHRC.

Interesting time-lapse video of salt marsh

January 10, 2014

We have a sampling station set up in Groves Creek on the east side of Skidaway Island as part of a salt marsh study. One added element is a time lapse camera. This short video is pretty cool. Enjoy.

Skidaway Institute scientists seek answers to salt marsh questions

January 2, 2013

Salt marshes are a vital part of the coastal ecosystem. They provide a nursery for many kinds of marine animal life. Sitting in the transition zone between the ocean and the land, salt marshes serve as a physical buffer against severe weather. They act as a chemical buffer by capturing, holding and releasing nutrients that are brought in on each tide. As a result, the marshes have a great influence on the type and amount of nutrients that enter the sounds and the ocean. That buffering capacity varies on tidal, daily and seasonal time scales, but how it functions is poorly documented.

A team of Skidaway Institute of Oceanography scientists have begun a project to get a clearer picture of how salt marshes function and interact with their surrounding environment.

The composition of the science team reflects the interdisciplinary nature of the project. Principal investigator Jay Brandes, Aron Stubbins and Bill Savidge are chemical oceanographers, and Catherine Edwards is a physical oceanographer. Geologist Clark Alexander and physical oceanographers Jack Blanton and Dana Savidge are also contributing to the effort. The three-year project is funded by a $699, 971 grant from the National Science Foundation.

The research team at Groves Creek (l-r) Clark Alexander, Jack Blanton, Catherine Edwards, Jay Brandes, Dana Savidge, Bill Savidge, Aron Stubbins

The research team at Groves Creek (l-r) Clark Alexander, Jack Blanton, Catherine Edwards, Jay Brandes, Dana Savidge, Bill Savidge, Aron Stubbins

“Scientists have looked at salt marshes in the past and have gotten some good data,” Brandes said. “However, this will be the first detailed look at the combined functions of one of these marsh systems.”

The project will focus on Groves Creek, a portion of coastal salt marsh along the Wilmington River, adjacent to the Skidaway Institute campus. Groves Creek has been the site of other research projects.  Over the past three years, Blanton, Alexander, Dana Savidge and others have studied the topography and water-flow in the marsh as part of a Department of Energy-funded project.  Because of this, the physical layout of the marsh has been documented to a fine detail.

“We already know a lot about this area, especially how the water moves in and out of the marsh on the tides,” said Brandes. “We have a very good understanding of the topography of the top of the marsh and its tidal creeks, both above and below the surface.”

The scientists also believe the Groves Creek area is fairly representative of salt marshes along the Georgia and South Carolina coasts.

From a chemical standpoint, the research will focus on way the salt marsh uses carbon: is it a consumer or producer of carbon-based organic material and nutrients?

“Marshes take material in from the river on every high tide, and they deliver material back to the river on the falling tide — but it isn’t the same stuff,” Savidge said. “The marsh changes the river chemistry on every tidal cycle.”

There isn’t much consensus on what controls that exchange between river and marsh. “That is one of the big questions,” said Brandes, “Trying to understand whether the marsh is a producer or consumer, and how that changes over time, the seasons, the tides and so on.”

To get a detailed history of marsh-river exchange, the scientists will place sensors in the marsh that will measure various conditions every 15 minutes. Remote sensors cannot measure everything, so the research team will also be collecting samples on a daily basis and returning them to their labs for analysis.  Understanding the big picture will come from adding up all the little incremental changes over time and relating them to the actions of sun, tide and weather on the marsh surface.

Stubbins will focus his efforts on the role of dissolved organic carbon in the marsh. Savidge will work look at how the salt marsh uses dissolved oxygen. Edwards will be modeling how water flows in and out of the system and how that movement interacts with the chemical and biological activity.

When the project is complete in three years, the Skidaway scientists expect to have a much more extensive picture of the role salt marshes play in the larger coastal ecosystem.

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Little help for marsh from eco-friendly dock designs

April 25, 2012

New dock designs intended to reduce damage to salt marshes are not much better than traditional docks, according to a recently completed study by Clark Alexander of Skidaway Institute of Oceanography. Alexander also concluded the compass orientation and height of a dock has more impact on the health of the salt marsh than the dock design or materials.

The problem is the shadow docks cast on the salt marsh vegetation beneath them. The marsh grass (Spartina alterniflora) does not flourish in reduced sunlight.  In recent years, alternative materials and designs have appeared on the dock-building market to try to mitigate this problem. Alexander tested three types of alternative material and designs – ThruFlow fiberglass-impregnated plastic grating; Gator Dock Fibergrate grating; and the DockRider Sundock, which uses a set of wooden rails and an electric trolley in place of traditional wood planking.

“These all sounded good,” said Alexander. “But what we didn’t know was if they actually worked effectively.”

To answer that question, Alexander conducted a three-year, two-part research project funded by a $195,488 grant from the Georgia Coastal Zone Management Program.

The first part of the study was to conduct field-based “before-and-after” studies of salt marshes where some of the new designs were being built. Alexander’s team collected samples and recorded conditions in the marsh before the docks were built and continued to monitor the salt marshes after they were completed.

In the second part of the study, Alexander and his team constructed four dock models, “mock docks”, using alternative materials on high ground at the Skidaway campus. The docks were placed in a field with unobstructed sunlight and were fitted with light meters that measured the amount of sunlight being received above and below each dock. The researchers measured the shadow footprint of the various dock designs over the course of two years.

Clark Alexander (r) and research team member Mike Robinson examine the light meter equipment beneath on of the mock docks.

“Because orientation is an important parameter in light transmission through these materials, we made the mock docks mobile, so we could re-oriented them during the four seasons to see the effects of orientation and seasonal sun angle” said Alexander.

They also adjusted the dock heights to assess the impact of height on light penetration to the ground below.

In the first part of the study, Alexander and his team examined three separate field sites – Turners Creek (ThruFlow decking), Shell Point Cove (Dockrider) and Betz Creek (traditional plank design) They measured the stem density of the marsh grass before the docks were constructed and then monitored it for two years after construction. Stem density in the dock shadow footprint decreased between 44 and 80 percent compared to nearby, non-dock sites.

The team also observed additional dock-related impacts. Some sections of salt marsh transitioned to denuded mudflats due to the marsh wrack that accumulated around the dock pilings.

The results of the field study were supported by the mock-dock project on the Skidaway campus. Seasonal measurements showed a significant reduction of the light needed to support the health of the marsh plants in the areas affected by the docks’ shadows.  At Skidaway Institute’s latitude, the elevation of the sun is high enough to allow sunlight to penetrate through the grated deck material only during the spring and summer, and even then, provides only about 10% more light than traditional plank decking.

The mock-dock project also documented two additional dock-shading impacts.  The compass orientation of a dock plays a significant role in the effect the dock has on the marsh. Docks that are oriented in a generally north-south direction have a much smaller shading impact than those oriented east-west. The height of the dock also has a significant effect. The duration of the shadow under the dock and the total light loss decreases as the height increases, up to 7 feet above the marsh surface, with smaller, less significant decreases above that height.

“The results of the two studies demonstrate that neither current alternative materials nor construction methods effectively negate the effects of dock shading in our region,” said Alexander. “However, the Dockrider system had one half to one third the shading impact of decked walkways in our study.”

“In addition to shading impacts, marsh wrack accumulation around dock and walkway pilings also negatively impacts the marsh and will be a problem with any piling-supported structure.”

The results of the study have been sent to the Department of Natural Resources, which will use these results to better manage the important coastal saltmarshes of Georgia.

Some nice news coverage

January 4, 2012

Clark Alexander’s project on erosion on the Intracoastal Waterway generated some good news coverage.

Mary Landers from the Savannah Morning News wrote this story that was published last week.

Alice Massimi, from WSAV-TV (local NBC affiliate), shot this story before Christmas, but it aired yesterday.

Enjoy!