Tag Archives: biology

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’s Diaz studies the tiny organisms with a big impact

Like many oceanographers, Julia Diaz is difficult to categorize. Is she a biologist, or is she a chemist? The answer is — a little of both. Diaz’s research interests lie where biology and chemistry meet.

“My absolute favorite thing in the world is looking at phytoplankton under the microscope,” she said. “And I am also very passionate about chemistry.

OLYMPUS DIGITAL CAMERA“Our chemical environment really shapes our health and impacts our climate and all kinds of natural resources. So I am interested in the intersection of those two parts of nature — how tiny microscopic life interacts with the invisible chemistry out there to shape the environment in some pretty big ways.”

Diaz joined the faculty of UGA Skidaway Institute of Oceanography in fall 2015 as a homecoming of sorts. She was raised in Alpharetta just outside Atlanta. She graduated summa cum laude from the University of Georgia with a degree in biology and then went on to earn a Ph.D. in earth and atmospheric sciences from Georgia Tech. Her postdoctoral work took her to Harvard University and Woods Hole Oceanographic Institution.

Diaz targeted science as her future from an early age. Her father is a retired Georgia State University professor, and her entire family was involved in education. Her brother is an astrophysicist, and she jokes that they study opposite ends of the universe—with her specializing in the very small while he studies the very large.

“I grew up talking about science with my dad, my brother and my mom,” she said. “It was always on my mind, and I was pretty good at it. It felt good to learn and to always be exploring new things.”

As an undergrad at UGA, her interest in science grew into a passion.

“I got into some really cool classes, where we basically spent two days out of the week staring down a microscope at pond water and it was just the coolest thing,” she said. “All these creatures that you would never imagine are there. It’s amazing — this whole other world that really drew me in.”

In graduate school, Diaz focused more on chemistry to complement her background in biology.

“I originally got interested in marine chemistry and biology because I was inspired by the fact that, billions of years ago, marine microbes created oxygen and other life-giving chemicals to make this planet the habitable place that it is,” she said.

Diaz’s work has taken her from the Caribbean to Antarctica.

“One of the best parts about this job is that it lets you see the world. Antarctica was the most amazing experience — you never get tired of seeing penguins,” she said.

Diaz with her penguin friends

Diaz with her penguin friends

“Personally, I never got tired of looking at Antarctic phytoplankton, either. They can attach to the underside of sea ice, making it look like it’s been dipped in coffee, but under the microscope, it’s like peering inside a jewelry box of gorgeous single cells, so many ornate shapes and vibrant colors. It’s just magical.”

Many of Diaz’s projects focus on phytoplankton — microscopic plantlike organisms that drift with the ocean’s currents. They form the base of the marine food chain and produce half of the oxygen in the atmosphere. Among other projects, she studies how starving phytoplankton obtain the chemical nutrients they need from seawater, and she attempts to identify the enzymes that drive those biogeochemical processes.

Diaz is also interested in how phytoplankton convert chemical elements into forms that can be harmful or beneficial to life, such as reactive oxygen species, or ROS, types of oxygen with additional electrons. They are produced in all living things as a byproduct of metabolism.

“ROS can be toxic, but they can also be very beneficial to life,” Diaz said. “They can serve as cell signals that promote growth and immune defense. Our own white blood cells produce ROS as a defense mechanism against invading pathogens.”

An important facet her work seeks to understand is how phytoplankton may use ROS to survive stressful situations, such as attack by predators. These ROS-driven processes may play a role in the formation and decline of giant phytoplankton blooms so large they can be seen by satellites.

She admits her work can be challenging to communicate outside of her field, because much of the research cannot be seen by the naked eye. However, she said, those invisible chemical processes are occurring in the ocean over sizeable areas and long time periods, and they produce large visible effects that shape our daily lives.

“From starvation to cell defense, a lot of the work I do relates to stress in the oceans — how marine life copes with stressful conditions, how stress changes the chemistry of the oceans and ultimately how that changes the environment on a global scale. The oceans are under increasing amounts of stress due to climate change, pollution and other human impacts, so I think this kind of research has an important place in the understanding of our changing planet.”

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Black gill stakeholders meeting set for June 22

As the 2016 Georgia shrimping season gets underway, the University of Georgia Marine Extension and Georgia Sea Grant, and the UGA Skidaway Institute of Oceanography will host a meeting to present the latest research and other information on black gill in Georgia and South Carolina shrimp. The meeting will be held at the UGA Marine Extension Aquarium at the north end of Skidaway Island in Savannah, Ga. on Wednesday, June 22, from 1-4 p.m.

Black gill is a condition affecting the coastal shrimp population. It is caused by a microscopic parasite. Many shrimpers believe black gill may be largely responsible for reduced shrimp harvests in recent years. UGA Skidaway Institute scientist Marc Frischer is leading a research project, now in its third year, into the causes and effects of black gill on the Georgia and South Carolina shrimp population.

A shrimp with the Black Gill condition clearly evident.

A shrimp with the Black Gill condition clearly evident.

The purpose of the meeting is to provide stakeholders, such as shrimpers, fish house owners, wholesalers or anyone else interested in black gill, with an update on black gill research efforts.  Frischer and South Carolina Department of Natural Resources scientist Amy Fowler and will present their latest research findings. UGA Marine Extension and the Georgia Department of Natural Resources will also provide updates. The meeting will be open to the public.

The meeting is for information purposes only. No management decisions will be made.

For additional information, contact Bryan Fluech, UGA Marine Extension, at (912) 264-7269.

What: Black Gill Stakeholders Meeting

When: Wednesday, June 22, 1-4: p.m.

Where: UGA  Aquarium, 30 Ocean Science Circle, Savannah, Ga., 31411

Directions: http://marex.uga.edu/visit_aquarium/