A new study, published in the journal Global Change Biology, which used physiological experiments and ecological models, proposes that future climate change scenarios will favor its expansion towards the end of the century.

Andrea Navarro, IDEAL Center. Halicarcinus planatus is a small crustacean, commonly known as “southern crab,” which is distributed in shallow coastal waters. It lives in the extreme south of South America, including the regions of Aysén and Magallanes and also the subantarctic islands of the Southern Ocean (Malvinas, Marion, Crozet, Kerguelen and Macquarie.) It tends to be more abundant in protected areas such as bays, straits, and inlets.

In 2010, an American researcher found on Decepción Island, located in the Antarctic Peninsula (south of the South Shetland Archipelago), a female with eggs of this species. The event aroused the curiosity of a team of scientists, as reaching the Antarctic shores requires dispersal through vast and deep biogeographic barriers that have isolated the continent for millions of years, including the crossing of the Antarctic Circumpolar Current.

This is how the group of researchers carried out a study, which results were recently published in the journal Global Change Biology, that states that nowadays the southern crab cannot establish itself in the waters of the Antarctic Peninsula. However, this situation is highly likely to change under the projected climate change scenario in the 21st century.

The work was developed thanks to the collaboration of a multidisciplinary team of experts from national and foreign institutions: Center for Dynamic Research of High Latitude Marine Ecosystems of the Austral University Chile (IDEAL-UACh), University of Magallanes (UMAG), University of Chile (UChile), University of Otago (New Zealand), Royal Belgian Institute of Natural Sciences (Belgium), Université Bourgogne Franche-Comté (France) and Université Libre de Bruxelles (Belgium). In addition, this multidisciplinary study was supported by the projects “Inach-thesis (INACh DG_14-17,) Fondecyt-1161358, PIA CONICYT-ACT172065, Fondecyt 1160877 and, of course, the Centro Fondap-IDEAL 15150003.

To conduct the study, the researchers used a combination of physiological experiments and ecological models to assess the potential niche of Halicarcinus planatus and estimate its future limits to the south under climatic conditions.

“As a result of the warming that Antarctica has suffered, since the mid-20th century, and the increase in anthropogenic activities, the probability that exotic species will reach the white continent is greater and also the probability of establishing themselves there. Although, to date, there are no established exotic marine species, this situation could change over the years,” says Zambra López, marine biologist, doctoral student and co-author of the scientific work.

Research shows that the southern crab has a minimum thermal limit of 1°C, and that its current distribution (assessed by sampling and niche modeling) is physiologically restricted to the subantarctic region. While this species is currently unable to survive in Antarctica, future warming under ‘strongly mitigated’ and ‘no mitigation’ greenhouse gas emission scenarios will favor its niche expansion to the West Antarctic Peninsula by 2100. Human activity also has the potential to increase the probability of anthropogenic translocation of this species to Antarctic ecosystems.

The presence of this crab in Antarctica could be random, however, it is also possible that at some point it could be present in high density.

Successful Antarctic invasions to date have been exclusively recorded in terrestrial habitats. Although non-native marine species such as crabs, mussels and tunicates had already been reported off the coasts of the white continent, they have not yet established themselves there. Even if the full consequences of Antarctic warming have not yet been understood, some changes in the distribution and composition of communities have already been observed.

“Today our work shows that this crab cannot withstand Antarctic winters, which makes establishing and reproducing not viable yet. This would change due to the effects of climate change that continue to increase the temperature, making this crab able to establish itself on the white continent throughout the year,” concludes the researcher from the IDEAL Center, Vice-rector for Research, Development and Artistic Creation (VIDCA) of the UACh and co-author of the study, Dr. Luis Vargas-Chacoff.

Read the research here.