Posts Tagged ‘marine research’

UGA Skidaway Institute scientists study microbial chemical warfare

April 18, 2017

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.”

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.

A microscopic view of a population of 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.

NOTE:  A complementary video with an interview with Dr. Harvey is available at



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.

Skidaway Institute scientists use microscopic algae to track coastal water quality

January 12, 2009

As burgeoning growth on the Georgia Coast puts additional pressure on the fragile coastal environment, scientists at the Skidaway Institute of Oceanography are researching new techniques to monitor coastal water quality.liz-mann-lab-1

Scientists can measure water quality several ways. One method is to measure the water’s chemical characteristics, such as oxygen and nutrient concentrations. Skidaway Institute researcher Elizabeth Mann is investigating another technique – using a group of microscopic organisms as a bioindicator of water quality.

“When you measure the chemical composition of the water, you essentially get a snap shot of all the individual components in the water at the time you take your sample,” Mann said. “We are trying to determine if the micro-organisms in the water will give us a better picture of water quality because living cells must adapt to all of the stresses in an environment over a longer time span.”

Mann’s research focuses on one of the smallest of microscopic algae or phytoplankton called cyanobacteria. These organisms are less than 2 microns in size and form the base of the food web. Like plants, cyanobacteria such as Synechococcus contain chlorophyll and manufacture their own food through photosynthesis.

Cyanobacteria have many characteristics that make them potentially good indicators of water quality. Synechococcus are abundant in Georgia’s coastal waters and are relatively easily isolated and grown in the laboratory. They can also be identified and counted using flow cytometry, a technique that can accurately count up to 500 cells a second.

“Cyanobacteria can serve like a canary in a coal mine,” said Mann. “Changes in Synechococcus populations may help monitor the condition of the environment in which they live because these small phytoplankton are more sensitive to toxic metals such as copper and cadmium than larger marine algae.”

Mann is examining the water quality in the Savannah River by comparing conditions in that heavily industrialized estuary to the more pristine Altamaha River.

The abundance of cyanobacteria, including Synechococcus, is much lower in the Savannah River than in the relatively pristine Altamaha,” Mann said. “Not only is the total number of cyanobacteria lower in the Savannah River, but certain types of microbes abundant in the Altamaha River are essentially absent from the more heavily impacted Savannah River.

In addition, Mann said, adding water from the Savannah River to populations of estuarine phytoplankton from more pristine locations leads to a decrease in the abundance of cyanobacteria and other small phytoplankton.

Mann’s work is just beginning. A next step will be to identify the types of contaminants responsible for low Synechococcus numbers in the Savannah River and to determine what effect stunted cyanobacteria populations have on the larger organisms in the food web that prey on these small plants.