Some shark species able to adapt to climate change: study
Researchers look at shark teeth fossils from the Canadian Arctic
A new study has found that some sharks who lived in Arctic waters millions of years ago were able to cope with climate change — suggesting today’s species may also survive more recent warming of the climate.
As part of their study, researchers at the University of Chicago looked at sand tiger sharks’ teeth found in the western Canadian Arctic.
The teeth date back to between 38 and 53 million years ago during the Eocene area, when the Arctic was a temperate forest with brackish waters — an area of low salinity, where rivers and seawater meet.
Researcher Sora Kim isolated and measured oxygen isotopes found in the shark teeth — a measure that usually reflects ocean temperature and salinity.
“The numbers I got back were really weird,” Kim said in a University of Chicago release. “They looked like fresh water.”
Sand tiger sharks, part of a group called lamniform sharks, prefer waters with high salinity.
They are still present along the east coast of North America, and in more southern waters off the coasts of Australia, Japan and South Africa.
While fears that current climate change may further contribute to a declining population of sharks, the study’s findings suggest that some shark species could handle the falling salinity that may come with rising temperatures in the Arctic, as more freshwater is expected to flow into the Arctic Ocean.
Although the Eocene-era Canadian Arctic region home to a variety of animal life, including hippo-like creatures, crocodiles and giant tortoises, marine records have been hard to find.
Shark teeth are one of the few marine fossils available from the time period, as they preserve well.
Kim describes the time period as a “deep-time analogue for what’s going to happen if we don’t curb CO2 emissions today, and potentially what a runaway greenhouse effect looks like.”
Canada is home to more than 20 species of shark, although few, like the Greenland shark, inhabit Arctic regions. Two — the basking shark and the white shark — are listed under Canada’s Species At Risk Act.