Using sensors installed in crabeater seals, satellite instruments, and statistical and ocean models, a team of researchers obtained unpublished information. The work was published in the prestigious scientific journal Nature Climate Change.

It is estimated that 98% of the crabeater seal feed is krill. © Mireia Mestre.

Andrea Navarro, IDEAL Center. If you know the behavior of the predator, you will understand how its prey moves. This phrase could belong to a book of the police genre, but it is not the case. That was the premise that a team of scientists used to carry out a multidisciplinary study that showed projections of the effects of climate change on the Antarctic Peninsula, so far, unknown.

In order to contextualize the results of the research, one must locate oneself at the southern end of the planet, specifically on the white continent. Crabeater seals live there, the most abundant large mammal on Earth after humans. It is considered a very important predator and, unlike other species, does not usually form colonies. It lives associated with sea ice.

On the other hand, the Southern Ocean is also the home of the krill, a small crustacean that, as an adult, measures between three and six centimeters. It is known as the “key link” of trophic cascades, as it is the main food for whales, fish, pinnipeds, penguins and seabirds. However, these are not the only animals that eat the desired euphausiid.

It is estimated that 98% of the crabeater seal feed is krill. In fact, its teeth have modifications to filter them better. They are the only crustacean predators that remain throughout the year in Antarctica, unlike, for example, whales that only arrive in summer.

Taking this background into account, a team of scientists carried out an investigation, the results of which were recently published in the prestigious journal Nature Climate Change, and indicate that krill will change its current distribution: It will move away from the coast, moving towards more oceanic areas, and the south of the Antarctic Peninsula, close to the pole.

The work was led by the University of California, in conjunction with the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACh) and the universities of Oregon State, San Jose State, Old Dominion, Alaska Anchorage and Sonoma State.

“The data shows that there will be a decrease in krill densities in coastal waters, which will have an impact on the food webs. Probably, the animals that eat this crustacean, in the future will have to travel much larger distances to find it,” says the marine ecologist at the University of California, Santa Cruz, and study leader, Dr. Luis Huckstadt.

Scientific work determined that krill distribution will vary based on three key factors. © Dan Costa.

But how did they come to this conclusion? The researchers realized that if they could understand the behavior of the crabeater seal, they could model the data and thus understand what the distribution of krill will be in the future.

To carry out the scientific work, in the first instance, they installed sensors in the crabeater seals that gave references to the routes of displacement, the depth of the dives, salinity, temperature and density of the sea, among others. The devices directly sent the data to satellite instruments. With the information obtained, scientists were able to feed a statistical model that allowed them to carry out the projections and that was able to representatively solve the conditions of Antarctica.

“One of the projections of future climate change scenarios indicates that westerly winds on the Antarctic Peninsula will intensify. As a result, we force environmental conditions: We increase the winds by 20% and we increase the transport temperature of the Antarctic Circumpolar Current in the subsurface,” explains the physical oceanographer of the IDEAL Center and co-author of the research, Dr. Andrea Piñones.

Three key factors

Scientific work determined that krill distribution will vary based on three key factors: Ocean circulation, water temperature, and sea ice distribution. The projections of the biomass of the crustacean will be negatively affected by these variables.

Can marine organisms that feed on crustaceans adapt to future conditions of climate change? To answer that question, it is necessary to continue investigating.