Archive for December, 2009

Skidaway Institute researcher maps armored shorelines

December 10, 2009

Skidaway Institute of Oceanography researcher Karrie Brinkley has spent a lot of time in recent months traveling up and down Georgia’s coastal waterways in boats and canoes with maps and binoculars in hand. Brinkley is working on a project to identify and map all the armored shorelines in the state’s six coastal counties.

Brinkley has been looking for bulkheads, causeways and rip-rap – the piles or rock or concrete frequently used to stabilize a shore or river bank. The purpose of the study is to establish a baseline set of data to help understand and project the effect of rising sea level on the Georgia coast.

Karrie Brinkley examines a bulkhead armored shoreline on Skidaway Island.

“The shorelines are going to act differently as the sea level rises, depending on whether they are armored or not,” said Brinkley. “In this project, we want to see how much of the coast is armored and what type of armory is being used for individual sections as well as the entire coast.”

Brinkley is working under the guidance of Skidaway Institute professor Clark Alexander. He says that currently the oceans are rising at approximately three millimeters per year, or roughly a foot per century, however many scientists project that rate could double, triple or quadruple in coming decades. This could have a tremendous impact on coastal areas.

“One environmental area of concern is the salt marshes,” said Alexander. “If the sea level gradually rises along a natural coast, the salt marshes that thrive in the intertidal zone will gradually migrate to the upland.

“However, if a section is armored, the intertidal zone may become completely submerged, and we would lose the function of the salt marsh in that area.”

The study is funded by the Georgia Department of Natural Resources, under the umbrella of a larger Environmental Protection Agency project. Geographically, Brinkley is studying all the coastal shores, from the beaches westward to either Interstate 95 or US Highway 17, which ever is further to the west.

For the first ten months of the project, Brinkley spent her time in front of a computer, studying aerial photographs of the coastal counties. Using a Geographical Information System program, she electronically marked the photos to indicate causeways, bulkheads, rip-rap and other shoreline armor.

An aerial photo of Wilmington Island showing causeways in purple and shoreline armor in yellow.

“Depending on the resolution of the photography, you can identify a lot from the photos,” Brinkley said. “Bulkheads show up as straight lines, and the bright stones of concrete rip-rap are fairly obvious as well.”

There are still many areas that Brinkley cannot characterize from the aerial photographs due to poor resolution, foliage overhangs or other reasons. Even the tide cycle when the aerial photography was shot can affect how much information can be gleaned from the photos. “A high tide may cover some rip-rap and make it invisible in the aerial photograph,” Brinkley said.

For those sections, she gets in a car, a boat or a canoe and visits the sites personally.

Once completed, the project will be shared with officials in Georgia’s coastal counties. Brinkley expects to have the project completed early in 2010.

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Skidaway Institute scientists study Arctic climate change

December 1, 2009

Climate change will have profound effects on the Arctic ecosystem, and those effects may be felt around the world. Skidaway Institute of Oceanography professor Marc Frischer is launching a three-year project to examine the effects of rising temperatures in the Arctic and how those changes will impact the marine food web.

The project is funded by a $356,139 grant from the National Science Foundation (NSF).

“We know global climate change is impacting the fragile Arctic environment,” said Frischer. “Atmospheric concentrations of heat absorbing greenhouse gases including carbon dioxide are rising; the Arctic sea ice and permafrost are melting; and models are predicting significant changes in precipitation patterns in the Arctic.

“What we don’t know is how living systems will respond or adapt to those changes and how, ultimately we as humans will have to adapt to those changes.”

The work will be conducted in Point Barrow, the northernmost location in the US, at a NSF supported research station operated by the Barrow Arctic Science Consortium.

Pt. Barrow, Alaska, in winter

The landscape at Point Barrow is tundra that sits on top of as much as 1,300 feet of permanently frozen soil called “permafrost.” The concern is that with climate warming this permafrost will begin to melt and release an enormous amount of organic material into the coastal ocean.

“What you have now is have is up to 1,300 ft deep frozen soils consisting of ancient forest peat locked in the permafrost,” said Frischer. “What will happen when the permafrost starts to melt and that material, called humic acid, is released into groundwater, streams, rivers and ultimately into the ocean? That is what we want to know.”

Frischer’s focus will be on the microscopic organisms that comprise the very bottom of the Arctic Ocean food web. They include a wide variety of tiny organisms. On one end are the autotrophs, organisms that consume inorganic material and produce energy through photosynthesis, like plants. At the other end are the heterotrophs that consume organic material and obtain their energy from what they eat, like animals.

The humic acid material is rich in carbon, but lacks nitrogen, a key element that both autotrophs and heterotrophs need to make use of the carbon in the humic material. For every carbon molecule an organism uses, it will also need nitrogen.

“If you are going to grow more things, then that nitrogen has to come from somewhere,” said Frischer. “Our hypothesis is that as this humic material enters the coastal Arctic, there will be a greater demand for nitrogen at the base of the food web.”

Whoever gets that nitrogen, whether it will be the plant-like autotrophs or the animal-like heterotrophs, will determine how much organic production ends up farther up the food web in larger marine animals and eventually humans.

“This will all be set by whoever wins the war for nitrogen,” said Frischer.

Over the course of the project, Frischer and his team will travel to the Arctic several times a year. While in the Arctic, Frischer’s team will focus on making observations of the system and conducing experiments to determine what organisms are growing, which organisms are using the humic material, and determining where they are getting their nitrogen from and how they are doing it.

“We will manipulate the nutrients in the water samples and see how the different micro-organisms react,” said Frischer. “From that we should be able to project how the natural environment will react and ultimately contribute new data that help us understand and predict the biological effects of climate warming in the Arctic.”

Frischer will be working with two collaborators on the project, Patricia Yager from the University of Georgia, and Deborah Bronk from the Virginia Institute of Marine Science. Both Yager and Bronk received independent grants from NSF to participate in the study.