Researchers Journey to Antarctica

The Drake Passage is a notoriously rough stretch of water that lies between South America and Antarctica. It is well known as a gut-wrenching rite of passage for any eager explorer or committed scientist looking to reach the continent’s western shores, but it sometimes shows travelers its softer side.

A research team from Bigelow Laboratory had the pleasure of experiencing this firsthand last December, enjoying a relatively calm voyage across the often-treacherous waters. The Drake’s unexpected mercy gave them an opportunity to jumpstart their research, and the team went to work assembling equipment and mapping out schedules. For the next two months, they would maintain a grueling pace in order to complete their research before it was time to again board the RV Laurence M. Gould for the return trip to Chile.

The scientists traveled to Antarctica to study the relationship between phytoplankton and bacteria and learn how one critical compound may help shape microbial communities in the icy Southern Ocean. 

While that might initially sound like an esoteric endeavor, the interaction the team is studying has huge implications for our changing and warming planet. Certain phytoplankton produce copious amounts of a com pound called dimethylsulfoniopropionate (DMSP). DMSP provides essential nutrients to marine bacteria and leads to the release of dimethyl sulfide (DMS) — a gas that helps form clouds and may therefore play a key role in regulating the Earth’s climate.

“We want to know how the diversity of life in the ocean affects this very important process,” said Senior Research Scientist Peter Countway. “To do that, we’re looking at the changes that occur in the community, as well as the specific genes that are associated with the use of DMSP.”

The cycling of DMSP provides a narrow focal point through which the scientists can study the complex relationship between bacteria and phytoplankton. They hope to be able to scale up what they learn to gain insights into other microbial interactions of profound influence.

“We need to understand how phytoplankton and bacteria interact throughout the entire ocean, but we have to start small,” Matrai said. “We already know they are interacting, but we can’t yet quantify it. When we have that information, we can use the data to build models and conduct simulations of more widespread processes.”

Phytoplankton and bacteria depend on each other to grow and survive. In the same way that humans rely on a healthy relationship with the bacteria inside us, there is a similar codependency between phytoplankton and bacteria in the ocean.

This relationship has been extremely difficult for scientists to examine and many basic questions remain regarding production and use of DMSP by microbial communities. Molecular tools, however, are now providing scientists with new ways to examine the relationship, connecting physical and chemical measurements to genetic information.

This cutting-edge approach is what sent Countway and Matrai to Palmer Station. They were joined on the expedition by Senior Research Associate Carlton Rauschenberg, as well as Kathryn Moore, an alumna of the Changing Oceans semester-in-residence program run by Bigelow Laboratory and Colby College.

Palmer Station, the smallest of the US Antarctic Program’s research outposts, is located about 700 miles south of Chile on the west Antarctic Peninsula. While the station population varies throughout the year, it hovers around 40 people throughout the busy summer season.

Conducting research in Antarctica is everything people think it is, as well as a lot of things people wouldn’t expect. The team navigated around icebergs and wildlife as they collected their samples aboard a small boat near the station. However, warm showers, reliable Internet access, and tourist cruise ships were no less common during their two-month stay.

“There were times when we were sampling and a humpback whale would pop up 10 feet from the boat or a passel of penguins would come by just to check us out,” Rauschenberg said. “And on our day off, we had a hot tub, sauna, bar, and two amazing chefs to help us get ready for another busy week of research.”

The team’s fieldwork primarily focused on a series of experiments, each taking about 10 days to complete. The scientists transferred sampled seawater into 12 four-liter bottles held in an incubator they designed. Six of the bottles were left sealed as control samples. The others were divided into two groups and provided with a steady supply of nutrients and DMSP at two different rates. The team used this setup to study the compounds in the water, the released gasses, the DMSP metabolism genes being activated, and the composition of the microbial community. 

“Through these short-term experiments, we could simulate an entire bloom cycle over the course of a few days,” Countway said. “This allowed us to simultaneously study the effects of DMSP production and consumption from multiple angles.”

The team used different seawater samples each time they ran the experiment, but they always exposed them to identical conditions. This allowed the scientists to examine the consistency of the interaction between different communities of phytoplankton and bacteria over the course of the Antarctic summer.

The team will be returning to Palmer Station in April 2018 to run the same experiments during a different time of the year. Life in the ocean goes through seasons just like it does on land, and different species of phytoplankton and bacteria will be “blooming” during their second visit. This will allow the scientists to further investigate the consistency of their results between communities.

“We first need to understand this interaction and how consistent it is,” Matrai said. “Then, we hope to use what we learn to examine other significant interactions that influence the health of the ocean and the planet.”