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.”

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 http://www.skio.uga.edu/news/videos/

 

Tiny but voracious marine organism studied — video

Tiny but all-consuming marine organism focus of UGA Skidaway Institute study

Marc Frischer

Doliolids are tiny marine animals rarely seen by humans outside a research setting, yet they are key players in the marine ecosystem, particularly in the ocean’s highly productive tropical and subtropical continental margins, such as Georgia’s continental shelf. University of Georgia Skidaway Institute of Oceanography scientist Marc Frischer is leading a team of researchers investigating doliolids’ role as a predator in the marine food web.

Doliolids are small, barrel-shaped gelatinous organisms that can grow as large as ten millimeters, or about four tenths of an inch. They are not always present in large numbers, but when they bloom they can restructure the marine food web, consuming virtually all the algae and much of the smaller zooplankton.

A doliolid with a cluster of juvenile doliolids on its tail. Actual size is approximately three millimeters, or one eighth inch.

“The goal of this particular study is to find out what the doliolids are eating quantitatively,” Frischer said. “This is so we can understand where they fit in the food web.”

Scientists know from laboratory experiments what doliolids are capable of eating, but they don’t know what they actually do eat in the wild. They are capable of eating organisms as small as bacteria all the way up to much larger organisms.

“What they are eating and how much are they eating from the smorgasbord that is available to them, that is the question,” Frischer said. “We are investigating how much of those different prey types they are really eating out there across the seasons.”

The project involves intensive field work, including 54 days of ship time on board UGA Skidaway Institute’s Research Vessel Savannah. During the cruises they conduct trawls using special plankton nets to collect the doliolids. They also collect water samples to understand the conditions where the doliolids thrive.

Graduate students Lauren Lamboley and Nick Castellane deploy a plankton net from the Research Vessel Savannah.

“We take the doliolids and the water samples back to the laboratory, and that is where the magic begins,” Tina Walters, Frischer’s laboratory manager said.

Because the animals are gelatinous and very delicate, the researchers cannot use classical microscopic techniques to dissect the animals and analyze their gut content. Instead they extract DNA from the animals’ gut and use sequence-based information to determine what the doliolid ate.

“We go through a process called quantitative PCR,” Walters said. “So even though we can’t see the prey in a doliolid’s gut, because the prey have unique DNA sequences, we can identify and quantify them using a molecular approach.”

The three-year project is funded by a $725,000 grant from the National Science Foundation and will run until February 2018. Frischer’s collaborator on the project is Deidre Gibson from Hampton University. Gibson received her Ph.D. from the University of Georgia in 2000, and did much of her graduate research at Skidaway Institute with Professor Gustav Paffenhöfer.  In addition to Walters, Savannah State University graduate student Lauren Lamboley is part of the team, along with a number of students at Hampton University. Several undergraduate research interns have also participated in the project, gaining hands-on research experience. Frischer is also working with the Institute for Interdisciplinary STEM Education at Georgia Southern University to engage K-12 teachers by inviting them to participate in the research cruises.

New imaging lab in the news

There was a nice article in Saturday’s Savannah Morning News regarding a new imaging lab at UGA Skidaway Institute.

http://savannahnow.com/news/2017-01-20/automated-microscopes-aid-crucial-ocean-work-skidaway

WSAV airs story on UGA Skidaway Institute black gill research

Savannah NBC affiliate, WSAV-TV aired an update on Dr. Marc Frischer’s ongoing research into the problem of black gill in Georgia shrimp.

http://wsav.com/2016/12/15/research-reveals-black-gill-kills-shrimp/

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.

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.”

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.

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.”

A sampling of phytoplankton imaged by the LIME’s FlowCam.

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.

Fall black gill cruise rolls out new research

The University of Georgia Skidaway Institute of Oceanography entered the fourth year of its black gill research program with a daylong cruise on board the Research Vessel Savannah and the introduction of a new smartphone app that will allow shrimpers to help scientists collect data on the problem.

Led by UGA scientists Marc Frischer, Richard Lee, Kyle Johnsen and Jeb Byers, the black gill study is being conducted in partnership with UGA Marine Extension and Georgia Sea Grant, and is funded by Georgia Sea Grant.

Black gill is a condition Georgia shrimpers first noticed in the mid-1990s. Many shrimpers have blamed black gill for poor shrimp harvests in recent years, but until Frischer began his study, almost nothing was known about the condition. Now the researchers know black gill is caused by a parasite—a single-cell animal called a ciliate—although the exact type of ciliate is still a mystery.

The October cruise had three goals. The first was simply to collect data and live shrimp for additional experiments.

 

“We were able to collect enough live shrimp in good shape to set up our next experiment,” Frischer said. “We are planning on running another direct mortality study to investigate the relationship between temperature and black gill mortality. This time, instead of comparing ambient temperature to cooler temperatures as we did last spring and summer, we will investigate the effects of warming.”

Researchers Marc Frischer (UGA Skidaway Institute), Brian Fluech and Lisa Gentit (both UGA Marine Extension and Georgia Sea Grant) examine shrimp for signs of black gill.

If his hypothesis is correct, Frischer believes researchers would expect that raising fall water temperatures to warmer summer levels in a laboratory setting will induce black gill associated mortality in the shrimp caught in the fall.

Those studies will be compared to those that are being conducted in South Carolina in a slightly different manner. Frischer expects the results should be similar.

“However, as it goes with research, we are expecting surprises,” Frischer continued. “We also collected a good set of samples that will contribute to our understanding of the distribution and impact of black gill.”

A second goal was to introduce and begin field testing a new smartphone application developed by Johnsen. The app is intended to be a tool that will allow shrimp boat captains and recreational shrimpers to assist the researchers by filling some of the holes in the data by documenting the extent of black gill throughout the shrimp season. The Georgia Department of Natural Resources conducts surveys of the shrimp population up and down the coast throughout the year. However, those surveys do not provide the researchers with the rich data set they need to really get an accurate assessment of the black gill problem.

A sample screen shot of the black gill smartphone application.

“Instead of having just one boat surveying the prevalence of black gill, imagine if we had a dozen, or 50 or a hundred boats all working with us,” Frischer said. “That’s the idea behind this app.”

The fishermen will use the app to document their trawls and report their data to a central database. Using GPS and the camera on their smartphone, they will record the location and images of the shrimp catch, allowing the researchers to see what the shrimpers see. If repeated by many shrimpers throughout the shrimping season, the information would give scientists a much more detailed picture of the prevalence and distribution of black gill.

“The app is complete and available on the app store, but we are still in the testing stages,” Johnsen said. “We want to make sure that it will be robust and as easy to use on a ship as possible before widely deploying it.”

Recruiting, training and coordinating the shrimpers will be the responsibility of UGA Marine Extension and Georgia Sea Grant.

“I think it should be entirely possible to at least have a small group of captains comfortable and ready to start using it when the 2017 season begins,” Frischer said.

Johnsen is excited about the app for what it can provide to the shrimping and research community, but also the implications it has for using apps to involve communities in general.

“There is still work to be done to improve the usability of these systems,” he said. “But I’m confident that we are going to see an increasing number of these ‘citizen science’ applications going forward.”

The final aim of the cruise was to bring together diverse stakeholders, including fishery managers, shrimpers and scientists, to spend the day together and share ideas.

“This was a good venue for promoting cross-talk among the stakeholder groups,” Frischer said. “I had many good conversations and appreciated the opportunity to provide a few more research updates.”

Georgia DNR’s Pat Geer sorts through the marine life caught in a trawl net.

Frischer says he thinks the communication and cooperation among the various stakeholder groups has improved dramatically since the beginning of the study. He recalled that when the study began in 2013, tensions were high. Shrimpers were angry and demanded that something be done to address the problem of black gill. Meanwhile, fishery managers were unclear if black gill was even causing a problem and frustrated that no one could provide them any reliable scientific advice. The research community had not been engaged and given the resources to pursue valid investigations.

“In 2016, we still have black gill. The fishery is still in trouble, but it does feel like we are at least understanding a bit more about the issue,” Frischer said. “Most importantly, it is clear that all of us are now working together.

“My feeling is that the opportunity for us to spend a day like that together helps promote understanding, communication and trust among the shrimpers, managers and researchers.”

Marc Frischer on morning radio program Thursday & Friday

Dr. Marc Frischer was a guest on the WTKS Radio morning show this morning to talk about black gill in shrimp. Thanks to Bill Edwards and Laura Picone for the invitation. They also taped a second interview which will be aired tomorrow morning. In Savannah, it’s 1290 on the AM dial.

Black gill TV story

We had a cruise yesterday that had two purposes — to collect data and samples for the black gill research project, and also to provide  a group of K-12 teachers an up-close-and-personal look at marine field research. We also had two TV reporters along. Here is the report from WTOC’s Marla Rooker.

http://www.wtoc.com/story/32211236/black-gill-continues-to-impact-georgia-shrimp

 

Skidaway Institute scientists study black gill in shrimp

Scientists at the University of Georgia Skidaway Institute of Oceanography are investigating black gill in shrimp, a condition Georgia shrimpers are blaming for an ongoing downturn in shrimp harvests. Very little is known about black gill, so professors Marc Frischer and Dick Lee are working with shrimpers and a number of agencies in a collaborative project to answer some key questions about the condition.

R/V Savannah crewman Chris Keene prepares to dump a load of shrimp and other marine life for inspection and study.

 Black gill is a symptom of a health problem in the shrimp. The affected shrimp are easy to identify because they exhibit large black areas on their gills, which are right behind their head. The black gill has no effect on the edible qualities of the shrimp. Shrimp affected with black gill are perfectly safe to eat, and the condition has no effect on the taste of the shrimp.

 Black gill has been an issue for pond-raised shrimp for more than a decade, but it has only been within the last several years it has become a problem for wild shrimp fishermen. Black gill can be triggered by several factors among pond-raised shrimp. Skidaway researchers believe black gill in wild Georgia shrimp is caused by a microscopic parasite classified as a ciliate—a single cell animal with tiny hairs called cilia that help them move. The scientists don’t know yet exactly which ciliate is to blame. The blackened gills are the result of the shrimp’s immune system reacting to the ciliate invasion. It creates black nodules around the invasive ciliates in the shrimp’s gills.

Three shrimp with black gill.

 Beyond the blackened gills, it is not known how the condition affects the health and morbidity of the shrimp. Shrimp shed their gills through their normal molting process. Scientists suspect the parasite triggers a molting response, causing the shrimp to shed their shells and gills repeatedly in an effort to rid themselves of the parasite. This may cause them to use up extra energy and leave them stressed and vulnerable to predators. Examination of infected gill tissue also reveals the ciliate can damage the shrimp gill and directly impact the ability of the shrimp to breathe.

 The Georgia Department of Natural Resources statistics indicate that at its peak in October 2013, 40 percent of the shrimp captured in its surveys had black gill. Shrimpers are blaming black gill for reduced catches last year and so far this season.

 “That may turn out that is the case, or it may not,” said Frischer. “As of right now, we have no scientific evidence to support it. That would be a good question to address in an additional research project beyond this one.”

 Frischer, Lee and their collaborators will try to determine how black gill is transmitted, and if it is infectious. They also want to determine the distribution of the condition and its causative agent, and also see if the parasite exists in other crustaceans, in sediments or in the water.

 According to Frischer, the black gill ciliate may always be present in the shrimp and probably other places too. For most of the year, shrimp are able to handle it. “However, in the late summer the water warms and the oxygen level drops, the shrimp may become stressed,” he said. “This may stress the shrimp and allow the parasite to proliferate.”

 The two-year project will be sponsored by a $140,000 grant from Georgia Sea Grant, a unit of UGA Public Service and Outreach. The funding is not yet official, but Skidaway Institute scientists began their work early because this is the time of year when black gill is prevalent. 

 Anna Walker of Mercer University is working with the Skidaway Institute researchers to conduct pathological tissue studies.

 Other collaborators on the project include UGA Marine Extension Service, Georgia Department of Natural Resources – Coastal Resources Division, the Georgia Shrimp Association, the South Carolina Department of Natural Resources, Southern Shrimp Alliance, the Florida Fish and Wildlife Conservation Commission and the North Carolina Division of Marine Fisheries.