A study led by Dr. Jorge Navarro, IDEAL center researcher, determined the species has a limited range of thermal tolerance.

Patagonian scallop inhabits the sub-Antarctic zone. Photograph by Jorge Navarro.

The Patagonian scallop (Zygochlamys patagonica), a species inhabiting the sub-Antarctic zone and of great commercial importance to the Magallanes Region, would not be able to adapt to warmer temperatures caused by climate change. This was the main conclusion reached in a study carried out by Dr. Jorge Navarro, a researcher for the Center for the Dynamic Research of High Latitude Marine Ecosystems (IDEAL) and the Institute of Marine and Limnological Sciences of the Universidad Austral de Chile (UACh).

According to figures from the National Fisheries and Aquaculture Service (Sernapesca), Patagonian scallop and southern scallop harvests (3660 tons) in 1998 were the largest catches ever made in the Magallanes Region. Two years later, catches had declined to just above 200 tons. Extraction of this resource is currently closed.

During the first IDEAL Center scientific campaign in October 2016, Dr. Navarro’s team extracted some 100 specimens of Patagonian scallop from 20 meters depth in Fiordo Pía, in the Beagle Channel. After acclimatization to the laboratory, specimens were exposed to different temperatures for 60 days. The main objective of the research, carried out in association with Alejandro Ortiz, Marine Biologist, and María José Agüero, Marine Biology Thesis Student, both at UACh, was to assess the species’ tolerance to current Antarctic temperatures and those expected under future scenarios of global change. For this, specimens were exposed to temperatures ranging from 1 to 15º Celsius.

“The Patagonian scallop was collected at approximately 4° Celsius. When exposed to extreme temperatures (15° Celsius) that could occur in some sectors of the Magallanes Region as a result of global change – according to data from the Intergovernmental Panel on Climate Change (IPCC) – mortality rates were 100%,” explains the researcher. Significant mortality was also observed at 12º Celsius (60%).

Based on these results, the scientists concluded that the Patagonian scallop is not able to adapt to warmer temperatures caused by global change.

“The species has a narrow range of thermal tolerance. We do not know what will happen in the future, but in the case of an abrupt increase in sub-Antarctic water temperature, the Patagonian scallop would not have the capacity to tolerate these conditions,” states Dr. Navarro.

Alejandro Ortiz, Marine Biologist, during the first IDEAL Center oceanographic campaign.

Could they move to the Antarctic?

The Patagonian scallop belongs to a group of bivalves that only inhabit the sub-Antarctic zone. To date, there has been no presence of this species in Antarctica.

“Another objective of our research was to know what would happen if the Patagonian scallop somehow managed to cross the Antarctic Circumpolar Current and reach the white continent,” says Dr. Navarro.

The scientist and his team found that, when exposed to waters at 1° Celsius, representative of Antarctic waters, the result was overwhelming: none of the specimens survived, with mortality rate of 100% by day 20.

“The Patagonian scallop can be considered a ‘stenothermic’ species, as it cannot withstand extreme conditions, due to inhabiting an environment with a low range of temperature variation,” he concluded.