Climate change likely leading to increase in jellyfish in B.C. lakes: researchers

Peach blossom jellyfish are shown in sample jars in this photo provided by UBC. (Credit: Polina Orlov)

There are already thousands of invasive jellyfish clones in B.C. lakes and the number could "increase rapidly" in the next decade due to the impacts of climate change, according to researchers.

Dr. Florian Lüskow and Dr. Evgeny Pakhomov, with UBC's department of earth, ocean and atmospheric sciences, are the only two researchers in Canada studying the "mysterious" peach blossom jellyfish, the university said on its website.

"We know very little about how they affect ecosystems and biodiversity of these systems in Canada, because the research hasn’t been done yet. The worry is that they harm indigenous species by outcompeting them," Lüskow said in a Q and A about the pair's most recent paper.

The creature, which is native to China and has spread around the world, first appeared in British Columbia in 1990. The species can only survive in climates where lakes are relatively warm and the province is the northernmost place on the continent in which they have been spotted.

"We do not know how and when introduction of the species occurred, but it was likely through medusa-producing polyps carried on recreational boats or on the bills or feet of birds when feeding," Pakhomov said.

According to Lüskow and Pakhomov, there were 84 sightings of the freshwater jellyfish recorded in 34 different locations between 1990 and 2023.

"Each sighting could be one or thousands of jellyfish," according to the researchers.

An increase in the number of sightings, according to an abstract for the paper, occurred during summer months with above-average temperatures.

Over the next 10 years, the pair predict there will be nearly as many sightings as there have been over the past 34 years and that the jellyfish will be seen in more locations.

"If climate change leads to freshwater temperature increases across B.C., we will likely see wider spread. Modelling indicates that even Alaskan reservoirs may potentially see invasion," Pakhomov said.

The peach blossom jellyfish only makes itself known to observers when the temperature in a body of water is higher than 21 C. that's when the researchers say they enter their "floating medusa form." Prior to that, they are in "polyp form" and much more difficult to detect. A polyp is about a millimetre in size, meaning "polyps could be in many more lakes without us knowing about it," the researchers said.

So far, Lüskow and Pakhomov have studied 100 of the jellyfish and have learned that they are not harmful to humans because their stings aren’t strong enough to pierce through skin. Another thing they found was that all 100 of the jellyfish were male and genetically identical, meaning they are "effectively clones" and can not complete their "sexual reproduction" – something that will ultimately limit the spread.

Still, the pair says assessing the prevalence of the jellyfish and understanding their impact on local ecosystems – including freshwater salmon -- will require further study.

To assist the researchers, people who spot these jellyfish are encouraged to report the sightings using iNaturalist or to the Invasive Species Council of BC.

The earliest one of the jellyfish has been reported is in July and the latest is in October. The jellyfish have been spotted in the Lower Mainland, on Vancouver Island and the Sunshine Coast and in the southern Interior.