Invasive Clone Jellyfish Are Spreading in North America Due to Climate Change

Freshwater jellyfish Craspedacusta sowerbyi Lankester, 1880 in the Suma Aqualife Park (Kobe, Japan).Photo byOpen Cage via Wikimedia Commons

“There is a thin semantic line separating weird and beautiful, and that line is covered in jellyfish.”
— Welcome to Nightvale

An unusal invasive species has been taking over lakes in North America.

The peach blossom jellyfish (Craspedacusta sowerbii) have now been found in 34 locations in North America, according to a recent study by Canada's University of British Columbia (UBC).

Researchers found that British Columbia is the farthest north the squishy marine critters have been spotted in North America. It's not the first time the peach blossom jellies have made the news. In 2022, they were found in a lake in Louisville, Kentucky.

Researchers found that human-driven climate change is expected to increase their range even further within the next 10 years.

"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," postdoctoral researcher at UBC Florian Lüskow, said in a statement.

The creatures were first noticed in British Columbia in 1990, primarily in the Lower Mainland, Vancouver Island, and along the Sunshine Coat. More recently, they've moved inward, expanding to Osoyoos Lake.

In the U.S., they were first reported in 1908. As of 2000, they were living in 43 of the 50 states, according to Animal Diversity Web. They were first recorded in England in 1880.

Squishy though they look — they're hardy creatures. They can live just about anywhere there's fresh water.

Freshwater lakes have been their home, but they can live in reservoirs, gravel pits, and in quarries.

They're not harmful to humans — their stings are for killing their favorite prey, tiny zooplankton — but concerns remain over their impact to local ecosystems. Invasive species — species that aren't native to a given area and are introduced some other way — aren't always bad for the ecosystem.

House geckos are one of the most commonly-seen invasive species in the U.S. They generally don't damage local ecosystems, just for for example.

"Between 1990 and 2023, a 34-year span, there have been 85 sightings, counted once per location per year, where each sighting could be one or thousands of jellyfish. But in this decade alone, we are predicting about 80 sightings, and likely in more than the 34 locations currently observed," Lüskow said.

The study also revealed an interesting quirk about the jellyfish — all of them are male. And more, they're all clones of one another.

These jellyfish are believed to have originated from a single polyp or cluster of polyps, the tiny stage of jellyfish life that resides at the bottom of a body of water.

"Polyps are very small, usually around a millimeter in size, and it is challenging to locate them. They inhabit shallow areas and can be found on rocks and submerged wood debris," Evgeny Pakhomov, professor at UBC's Earth, Ocean and Atmospheric Sciences (EOAS) department and the Institute for the Oceans and Fisheries (IOF), said in a statement.

The jellyfish are native to China. Their presence in British Columbia is closely linked with the region's climate — mild winters and warm summers.

Pakhomov explained that their spread may accelerate due to climate change, which is warming the region's freshwater systems.

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

What currently has researchers puzzled — and hopeful — is that, since all the jellyfish are male, they can't sexually reproduce. Ergo, they're restricted in how far they can naturally range and increase their populations. Still, they're quickly reproducing with cloning, and increasing their populations by the thousands.

Researchers are now focused on mapping the actual distribution of peach blossom jellyfish in British Columbia and understanding their impact on freshwater ecosystems, especially on young salmon populations.

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