A new study, led by Chilean geneticist Dr. Leyla Cárdenas, revealed that the influx of ships, the unusual increase in ocean temperature and the species’ physiological capacity, could provide a “window of invasion.” The research was published in the Scientific Reports journal.
When marine biologist Paulina Bruning was diving in the icy waters of Maxwell Bay, on the Antarctic Peninsula, she was unaware that the sponges she had collected that summer brought with them something that had not previously been recorded on the white continent. However, when analyzing the samples under the microscope, she realized that what she had found was significant.
A study published in the prestigious scientific journal, Scientific Reports (Nature Publishing Group), and headed by the Chilean geneticist of the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL, for its acronym in Spanish) of the Austral University of Chile (UACh), Dra. Leyla Cárdenas, revealed how important that finding was. After a series of laboratory analyzes, the presence of Mytilus cf. platensis -commonly known as Chilean mussels- was confirmed in the Southern Ocean.
The possibilities of finding non-native species in Antarctica existed. A recent investigation by a group of English scientists released a list of 13 species with high probabilities of invading the northernmost area of the white continent. That list was headed by Chilean mussels, considered as an important commercial resource for Chile. However, to date, no research group had managed to find them.
Using cutting-edge genetic tools, such as mitochondrial and nuclear markers, Dr. Cárdenas and a multidisciplinary team of experts from the University of Lával (Canada) and William College (United States), performed an identification based on DNA sequences. After that, they classified the organisms in the group of the Mytilidae. They then used a global database to determine the geographic association of the samples from Antarctica.
“This was not a casual finding. It is the result of a systematic work of monitoring, observation and evaluation of biodiversity that we have been carrying out for more than four years. Chilean mussels that have reached Antarctica require interaction with the environment and the protection of the substrate. At this time, this shelter is being given by sea sponges,” explains Dr. Cárdenas.
After various analyzes, the researchers determined that the individuals corresponded to the same genetic group of mussels that inhabits Patagonia (Chile and Argentina) and the Kerguelen Islands, located in the Indian Ocean. Despite this, the specimens found do not have the same density or abundance, since on the white continent they need association with other organisms to survive and for now they have found no evidence that they are capable of reproducing.
Window of Invasion
One of the most common mechanisms that marine invasive species use to get to other places is through boats. The large influx of this type of transport is a potential responsible for the arrival of exotic species. In general, it is believed that they can move through ballast water or adhere to hooves.
Taking this background into account, the researchers performed an information cross between the official record of the flow of ships arriving in the Antarctic Peninsula, the data on the temperature in the Southern Ocean and the physiological capacity of the mussel. Thanks to this, they discovered that an “invasion window” can be produced, allowing them to survive and settle in the waters of the white continent.
“According to our records, during the summer season there has been an unusual increase in temperature, which coincides with the season with the highest influx of ships, thus opening an opportunity for the entry of exotic species. This does not mean that there is an established population. We find only newly recruited individuals; however, any invasion process begins with the introduction of individuals. It is something that we must still study,” says the ecologist of the IDEAL Center and co-author of the study, Dr. Luis Miguel Pardo.
What about the future?
Scientific work shows that the mussels that were found are outside their historical geographic range. However, further research is needed to determine if these organisms will become abundant and dominant in Antarctic marine ecosystems.
The increase in temperature generated by climate change could open a door and generate local populations of exotic species if they become capable of reproducing.