In South Bay, located on Doumer Island, near the Antarctic Peninsula, a team of scientists installed a sediment trap, along with other instruments. The sediment trap is an oceanographic tool that will allow researchers to study the effects of fresh water contribution, or “freshening,” which results from the melting of glaciers.
Credit: Paulina Möller
Andrea Navarro, IDEAL Center. Studying the contribution of fresh water from melting glaciers in Antarctic bays was one of the objectives of a team of scientists from the Research Center: Dynamics of High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACh) and the Marine Sciences Institute (ICM-CSIC) of Barcelona, Spain.
Under the auspices of the Antarctic Scientific Expedition (ECA) 55, the chilean oceanographer Dr. Humberto González and the biogeochemist Dr. Enrique Isla together installed a monitoring system that will allow them to obtain one year’s worth of data covering the physical, chemical, and biological characteristics of South Bay, on Doumer Island (Antarctic Peninsula region). After months of preparation, the researchers, working jointly with the logistics team of the scientific ship Karpuj, submerged a sediment trap at a depth of 200 meters. This trap is an oceanographic instrument that will allow them to quantify the flow of particles in the water column in this part of the Southern Ocean.
The sediment trap is a cylinder that captures the particulate material that falls during a predetermined time interval over a specified area of the seabed. The system includes sensors for acidity, temperature, salinity and oxygen, along with a CO2 pressure sensor, which measures the difference in atmospheric carbon dioxide pressure with respect to that of the ocean.
This study has special relevance because most of the oceanographic work that has been done in the Antarctic has taken place in the open ocean. However, there is very little known about the annual cycles of the flow of particulates in closed coastal systems and the potential impact on these caused by retreating glaciers, resulting principally from global warming. “The information that exists today about the role of the key zooplankton species in the water column is limited. For example, what are the roles of krill, salps, and other organisms? How is organic matter being exported to the bottom of the ocean? These are some of the questions we hope to solve,” says Dr. Humberto González, director of the IDEAL Center.
Credit: Paulina Möller
Meanwhile, this monitoring system will allow researchers to obtain data during the entire year. As a result, they will be able to study the annual cycle of carbon export during the summer season, when the highest annual marine productivity takes place, as well as in winter, where the South Bay is covered with ice and there is practically no particle flow. In February 2020, the scientists will return to the site to download the accumulated data, maintain the equipment, and reinstall the anchor.
“The sampling strategy is for the long-term, which means that we will do a time series of at least four or five years. This will help us to better distinguish natural variations from the variations produced by human activity related to the characteristics of the environment,” explains Dr. Enrique Isla, the ICM-CSIC researcher.
Glacial and oceanic influences The installation of the measurement system was carried out in South Bay, since this is an area with considerable glacier and oceanic influence. The study area is ideal because it accurately represents polar weather conditions and is located near the Antarctic Peninsula where global warming is more evident than in many other regions around the world. In addition, this location offers satisfactory logistical facilities, since it is located near the Chilean scientific base Yelcho, belonging to the Chilean Antarctic Institute (INACh). The monitoring system anchored in South Bay was installed from the Karpuj, a vessel specially equipped for scientific work at high latitudes, featuring the ability to enter closed places inaccessible by larger vessels.
“Thanks to the joint efforts involving logisticians and scientists, the equipment was installed in the Southern Ocean. After waiting for a window of good weather and after three hours of work, the maneuver was successful,” concluded Jorge Acevedo, captain of the Karpuj.