Tag Archives: phytoplankton

NSF grant funds Diaz’s research

Julia Diaz

UGA Skidaway Institute researcher Julia Diaz is the lead scientist on a $852,906 three-year grant from the National Science Foundation titled “Collaborative Research: Assessing the role of compound specific phosphorus hydrolase transformations in the marine phosphorus cycle.” Diaz and her colleague, Solange Duhamel from the Lamont-Doherty Earth Observatory of Columbia University, will study how phytoplankton cope with shortages of phosphorus in the ocean, and if phytoplankton in phosphorus-rich environments also exhibit some of the same strategies. Skidaway Institute’s share of the grant is $296,831 and the funding began on Sept. 1, 2017.

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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.

UGA Skidaway Institute develops cutting-edge microbial imaging laboratory

A team of researchers from the University of Georgia Skidaway Institute of Oceanography has received a $226,557 grant from the National Science Foundation to acquire state-of-the-art imaging equipment to investigate microorganisms from the tiniest viruses to larger zooplankton. The equipment will be housed in UGA Skidaway Institute’s new Laboratory for Imaging Microbial Ecology, or LIME.

Researcher Elizabeth Harvey leads the research team that also includes UGA Skidaway Institute scientists Julia Diaz, Marc Frischer, James Nelson and James Sanders.

UGA Skidaway Institute researchers Tina Walters, Marc Frischer and Karrie Bulski practice running zooplankton samples on the FlowCam, a new instrument that is part of LIME

UGA Skidaway Institute researchers Tina Walters, Marc Frischer and Karrie Bulski practice running zooplankton samples on the FlowCam, a new instrument that is part of LIME

The equipment will improve Skidaway Institute’s capability to conduct field and laboratory experiments by automating many viewing methods.

“Anyone who uses a microscope will tell you that it is both tedious and time consuming,” Harvey said. “This equipment will allow us to enumerate and analyze microbes and other planktonic organisms much faster, and will allow us to do more large-scale projects than we could in the past.”

Microscopic phytoplankton photogaphed in the LIME.

Microscopic phytoplankton photogaphed in the LIME.

Much of the equipment will also have imaging capability so researchers will be able to do more detailed measurements on the size and shape of the tiny organisms and how that might relate to the health of an ecosystem.

Marine microbes are an essential component of all marine ecosystems and they play central roles in mediating biogeochemical cycling and food web structure.

“They are the things that drive all other processes in the ocean,” Harvey said. “They play a really important role in the way nutrients, oxygen and carbon are cycled through the ocean. We care a lot about those processes because they impact our climate, fisheries and the ocean’s overall health.”

The benefits of LIME will be shared beyond Skidaway Institute’s science team. Harvey envisions it as a regional center for microbial imaging, available to any other researchers who need the capability.

“Anyone is welcome to come here and get trained to use them,” she said. “They just need to contact me and we can make arrangements.”

Some of the equipment is already in place, while other pieces have not been delivered. Harvey anticipates all the equipment being functional by mid-2017.

Molecular-level relationships key to deciphering ocean carbon

by Alan Flurry

From beach shallows to the ocean depths, vast numbers of chemical compounds work together to reduce and store atmospheric carbon in the world’s oceans.

In the past, studying the connections between ocean-borne compounds and microbes has been impractical because of the sheer complexity of each. Three University of Georgia faculty members—along with an international team of scientists—bring to the forefront technological developments that are providing scientists with the analytical tools needed to understand these molecular-level relationships.

Their perspective article appears March 7 in the Proceedings of the National Academy of Sciences. It focuses on dissolved organic matter, or DOM, in the world’s oceans as a central carbon reservoir in the current and future global carbon cycle.

“Dissolved organic carbon is an amazing and confounding molecular soup,” said Aron Stubbins, co-author and associate professor of marine sciences at UGA housed at the Skidaway Institute of Oceanography in Savannah. “It sits at the center of the ocean carbon cycle, directing the energy flow from the tiny plants of the sea, phytoplankton, to ocean bacteria. Though around a quarter of all the sunlight trapped by plants each year passes through dissolved organic carbon, we know very little about the chemistry of the molecules or the biology of the bacterial players involved.”

The carbon the microbes process is stored in seawater in the form of tens of thousands of different dissolved organic compounds.

Researchers thought they had a handle on how some aspects of the process works, but “a number of new studies have now fundamentally changed our understanding of the ocean carbon cycle,” said the paper’s lead author Mary Ann Moran, Distinguished Research Professor at UGA.

In the context of methodological and technological innovations, the researchers examine several questions that illustrate how new tools—particularly innovations in analytical chemistry, microbiology and informatics—are transforming the field.

From how different major elements have cycles linked though marine dissolved organic matter to how and why refractory organic matter persists for thousands of years in the deep ocean to the number of metabolic pathways necessary for microbial transformation, the article infers a scale of enhanced and expanded understanding of complex processes that was previously impractical.

The perspective article, “Deciphering Ocean Carbon in a Changing World,” was shaped in discussions at a 2014 workshop supported by the Gordon and Betty Moore Foundation and Microsoft Research Corporation. Moran’s research has been supported by the Gordon and Betty Moore Foundation’s Marine Microbiology Initiative.

Co-authors on the paper include UGA’s Patricia Medeiros, assistant professor in the department of marine sciences. Others involved are with the Woods Hole Oceanographic Institute; the Scripps Institute of Oceanography and the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego; University of Tennessee, Knoxville; Oregon State University; Columbia University; The Pacific Northwest National Laboratory, Richland Washington; the University of Washington; University of Oldenburg, Germany; Sorbonne Universités; and the University of Chicago.

 

Death in the ocean keeps Skidaway Institute’s Harvey’s research alive

UGA Skidaway Institute of Oceanography scientist Elizabeth Harvey travels to the farthest reaches of the globe and in the nastiest weather to study microscopic marine plants known as phytoplankton. Last fall, Harvey spent a month on board a research ship in the turbulent North Atlantic as part of a NASA-funded project to learn more about these tiny organisms that are vital to life on the planet.

OLYMPUS DIGITAL CAMERAHarvey is one of UGA Skidaway Institute’s newest researchers, having joined the faculty in August of last year. Originally from Maine, she received her doctorate in oceanography from the University of Rhode Island and followed that with a position as a post-doctoral investigator at Woods Hole Oceanographic Institute. While she has a broad set of interests, phytoplankton have become the focus of her research.

“Phytoplankton are really important to a lot of different processes that impact life on Earth,” Harvey said. “They are at the bottom of the food chain so they are really important for feeding higher trophic levels like fish — and even higher — to whales really.”

Phytoplankton also play an important role in how nutrients and carbon are cycled around the world. It’s estimated that phytoplankton provide about 50 percent of the oxygen we breathe.

“So if you like breathing oxygen, you should like phytoplankton,” she said.

To study phytoplankton, she said, is to look into a world where lots of different interactions happen. Harvey’s work specifically focuses on the interactions between those single cell plants and the other organisms around them, including microzooplankton predators, bacteria and other phytoplankton. She hopes to better understand some of those individual interactions in order to make predictions on a larger scale.

“You wouldn’t think a single cell could be so dynamic, but phytoplankton are really complex,” Harvey said. “Rumor is NASA once took a look at one particular class of phytoplankton to see if they were extra-terrestrial.”

Using sensors on their cell surface, phytoplankton can sense their immediate surroundings — detecting organisms around them, sensing predators and modifying their behavior to escape predation. Some also produce toxic compounds in self-defense.

“Amazingly, they have very specific but very important interactions with other organisms,” she said. “You wouldn’t think a single cell could to that, but they do, and it can have some large-scale consequences.”

Last fall’s cruise on board the Woods Hole Research Vessel Atlantis was part of the NASA-sponsored North Atlantic Aerosols and Marine Ecosystems Study, or NAAMES. It was the first of a series of cruises to study an annual spring phytoplankton bloom in the North Atlantic. Harvey was one of 32 scientists on board. Her particular role was to measure phytoplankton mortality by both looking at the rate that phytoplankton were subject to predation or “grazing” by microzooplankton and also mortality due to viruses.

“I like to try to get people’s attention by telling them I am interested in death, which I sort of am,” Harvey said. “I am interested in how phytoplankton die.”

Understanding the relationship of phytoplankton mortality due to grazing compared to viral infections is important when trying to understand how carbon flows through marine ecosystems. The carbon from phytoplankton cells consumed by microzooplankton may continue to travel up the food web, while carbon from phytoplankton killed by viruses fuels the growth of other microbes, or could result in carbon sinking to the deep ocean.

Cruising the North Atlantic in November was no picnic. Harvey recalled 30-foot seas and 50-knot winds.

“That was a little adventurous,” she said. “We couldn’t do deck work. I didn’t tell my parents or husband about that.”

However, at 274 feet long and displacing more than 3,500 tons, the R/V Atlantis is a fairly large research ship, and Harvey says she never felt unsafe.

The days frequently started at 4 a.m. when scientists would lower an instrument package over the side to measure ocean conditions like salinity and temperature and to collect water samples. The scientists would work until eight or nine in the evening before catching some sleep and starting again the next morning.

“It’s a lot of long, hard work, but, on the other hand, your life becomes very simple,” she said. “The commitments in your normal life fade away. Someone even cooks your food for you every day.

“You work for long hours, but in the scheme of things, that is what you are there to do. There are no other distractions.”

Harvey says she was very happy to be part of the science team on the first cruise of the NAAMES project, and she enjoyed working with the other scientists on board.

“Everyone was very collegial and thrilled to be a part of a really cool project,” she said. “Scientists always like to get data, so sometimes I think that if I can be collecting new data, I am happy.”

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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