Thanks to the ability of this species to dive to great depths, a group of scientists obtained new information on the conditions of the Antarctic sea.

Antarctica is a complex territory, where climatic conditions, especially in winter, make it difficult for researchers to be on the ground to monitor the changes that the area faces during the year.

However, today it is possible to study the oceanographic conditions of the white continent thanks to one of the most important species that inhabits there: The Weddell seals. Monitoring the hydrological variables of the Antarctic Peninsula with the help of these specimens is a joint effort carried out by researchers from the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACh), the Center for Oceanographic Research in the South-Eastern Pacific (COPAS Coastal) and the BASE Millennium Institute.

The Weddell seal has an average length of 2.5 meters and a weight of up to 600 kg in males and is considered one of the largest in the Southern Ocean. They are expert divers and have the ability to dive up to 600 meters deep, holding their breath for more than an hour.

“Field study of conditions in Antarctica is advancing thanks to connectivity and, in particular, Weddell seals have proven to be an invaluable resource for monitoring data in periods where it is difficult to sample at sea, such as fall and winter, and in the depths under the ice sheets that cover it,” explained the researcher Dr. Andrea Piñones, leader of the Fondecyt project “Covering the gap: Characterization of winter hydrographic conditions and habitat use in the North Antarctic Peninsula, using instrumented seals and ocean modelling.”

The oceanographer leads a team that seeks to describe the variability in the hydrographic conditions of the upper water column along the northern shelf of the peninsula, including the north of South Shetland Island and the Bransfield Strait, given that the information available so far is limited. The new information will allow establishing measures for the conservation of this unique ecosystem.

“We hope that the project’s findings will contribute significantly to our understanding of the Antarctic ecosystem and guide future research in the region. Without a doubt, these fascinating marine creatures have proven to be valuable collaborators in scientific research in one of the most extreme regions of the planet,” commented Dr. Piñones.

In addition to describing the hydrographic conditions of the water column and understanding the inter-annual and climatic variability of winter processes, the research team seeks to understand the feeding and movement behavior of these mammals. To do this, they use advanced tracking and monitoring techniques, as well as the analysis of satellite images and ocean and sea ice models.

Choice of seals

The choice of Weddell seals as study assistants is due to the fact that this species does not migrate in search of food, which allows obtaining a complete record of the area of interest, since they remain close to their breeding territory throughout the year, feeding on a variety of prey such as Antarctic krill and various fish.

To choose the right seals, the researchers looked at their fur, selecting large, healthy adults. “It is a process where the sensor is attached to the back of the animal and it comes off due to the change of fur. This does not cause discomfort or harm the animal,” explained Octavio Mercado, COPAS Coastal oceanographer.

During the first year of this project, four sensors were installed, while in this latest expedition, five. “The amount of information that the teams deliver is enormous. Parameters such as temperature, salinity, pressure and location are recorded every time the seals submerge,” explained Paula Amador, oceanographer at the IDEAL Center, in charge of the instruments.

The scientists will also study the possible relationship between feeding of Weddell seals and vertical mixing in the water, where hotspots of particles, plankton, krill and nutrients are produced, in an area that is poorly accessible and not well known.