Two Temple University researchers from the College of Science and Technology—glaciologist/polar geophysicist Atsuhiro Muto and biologist Robert Sanders—are embarked on two long research projects in Antarctica funded by the National Science Foundation.
Muto, an assistant professor in the Department of Earth and Environmental Science, is on a nearly three-month research project to investigate how variations in atmospheric and oceanic conditions may be influencing the movement and melt rates, and the stability, of two massive, adjacent Antarctic ice shelves.
Sanders, professor and chair of the Department of Biology, is on a seven-week project. His team's focus: analyzing microscopic phytoplankton, or algae, found in the ocean that are able fuel their energy needs both via photosynthesis, from the sun's rays, and by ingesting food particles.
How fast are Antarctica's glaciers melting?
Muto, who has previously conducted research in Antarctica six times, is part of a joint United States-United Kingdom 11-person research team. They are working on TARSAN, the Thwaites-Amundsen Regional and Network: Integrating Atmosphere-Ice-Ocean Processes project. Their study is one of just eight international investigations of one of Antarctica's most unstable glaciers, the Thwaites Glacier. Some projections indicate that if Thwaites, which is about the size of Florida, fully melts in the coming centuries, it could raise global sea level more than three feet.
Muto's subgroup within the TARSAN project will be using seismic and gravity geophysical techniques to measure the depth of the ocean and the ocean floor underneath the Thwaites and nearby Dotson ice shelves. Another subgroup will conduct radar surveys and a third team will both drill the ice and install remote sensors that will provide feedback on oceanic and atmospheric conditions for two years.
"Knowing how deep the ocean is underneath the ice shelves is a key to understanding what might be going on and projecting into the future," says Muto. "If the ocean floor is shallow, it will be harder for warm ocean water to undercut the ice shelves. But a deeper trough could become a pathway for warm water to melt the glaciers faster."
Do polar winters cause algae to ingest food to survive?
Mixotrophy—the ability of some phytoplankton to both conduct photosynthesis and ingest food—has been known since the late 1800s. But not until the 1980s, when several scientists, including Sanders, began focusing on it, has the widespread prevalence of the phenomenon become apparent. According to Sanders—who also has studied the phenomenon in lakes and in the Atlantic and Arctic oceans—his research team are the only scientists that have investigated the question in the Southern Ocean.
To quantify the diversity of phytoplankton species they find in the ocean water and in sea ice, Sanders and his colleagues, who include researchers from the Woods Hole Oceanographic Institution and University of West Florida, will be using a variety of methods ranging from DNA analyses to microscopic and flow cytometric investigations. The team—which also includes Jean-David Grattepanche, assistant Temple research professor, and Christopher Carnivale, biology PhD candidate—will also experimentally determine ingestion of bacterial prey and productivity of both the microalgae and bacteria populations.
"Between half and three-quarters of all the photosynthesis that occurs in the world is conducted by these minuscule phytoplankton, which can't be seen with the naked eye," says Sanders, who will be conducting research in Antarctica for the fifth time. "But they are quite important because they are responsible for creating oxygen and food for all the animals in the ocean."
While it has yet to be proven, Sanders says the ability to also ingest food containing nitrates and phosphates could explain how these sunlight-dependent phytoplankton survive months of winter darkness.
-Bruce E. Beans