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Families find Manitoba's first jellyfish

Province studies impact of aquatic invaders

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Just when you thought it was safe to get in the water... well, it's still safe, but you might be getting a little jelly on your legs.

For the first time, a spreading species of freshwater jellyfish has been spotted in a Manitoba lake.

On Aug. 21, two families were taking a dip in little Star Lake, just northwest of Falcon Lake in the Whiteshell, when they realized they weren't alone in the water. "We jumped off the boats, we were swimming around enjoying the evening," Troy Milne recalls. "Then one of the girls said 'Look down, what does this look like?' "

Bobbing alongside them, about a foot below the surface: hundreds of tiny, translucent jellyfish. Stunned by the sight, Milne and his family, along with friends Bev and Harley Alexiuk and their kids, went to tell park attendants what they had found. At first, officials were skeptical of the sighting, so the families went back to the northwest corner of the lake again.

This time, they brought a jar and, a retired biologist later confirmed, they scooped up a bunch of the unfortunately-named freshwater jellyfish species, Craspedacusta sowerbyi. "We put them on the counter in front of the park people and said 'Here, what do you think these are?' Everybody's jaws dropped," Milne chuckles. "I've been out in that neck of the woods for 35 years, and never once have I ever heard or seen anything like this."

Officials from Manitoba Water Stewardship stressed that the species' identity had yet to be confirmed, but agreed that the Alexiuks' photos of the see-through critters appeared to be of a freshwater jellyfish.

Since busting out of China's Yangtze River valley over 100 years ago, the itty bitty jellies -- their gossamer heads can be as small as a penny -- have spread all over the world, with sightings on every continent except for South America. But they had never been seen in Manitoba, Alberta and Saskatchewan until Milne and friends splashed into them at Star Lake.

It's not unusual for the little fellows to suddenly blossom in waterways where they hadn't been spotted before, then disappear as cold weather moves in. Since they prefer water temperatures over 25 degrees Celsius, southern Manitoba's summer heat wave could have triggered their rapid spread at Star Lake, a spokeswoman for Manitoba Water Stewardship said. Officials speculated that the jellyfish could have hopped a ride to Star Lake with waterfowl.

Although scientists are still uncertain about how a Craspedacusta sowerbyi impacts ecosystems, "Manitoba remains concerned about any new invader entering our waters," Wendy Ralley, acting manager of Water Stewardship's water quality management section, said in a statement. She urged anyone else spotting an invasive species to contact conservation officials.

"Aquatic invasive species can significantly alter the ecology of our lakes, rivers, and streams, they can out-compete our native species for food and other resources, they can impact recreational activities, and can cost millions of dollars to control.

"Manitobans are reminded to clean, drain, and dry watercraft and related aquatic equipment before leaving a water source to reduce the risk of transporting unwanted species from one waterbody to another."

Meanwhile, the families that found the jellies are still smiling over the discovery. "The kids were quite excited when we told them that I think we're the first people to bring this forward," Milne says. "It's quite a unique situation."


That's right, Craspedacusta sowerbyi (say that five times fast) have been spotted in Manitoba for the first time. On Aug. 21, the little critters were found floating in the northwest corner of Star Lake in the Whiteshell.


Don't jellyfish like salt water?

Yep. Except for craspy over here. It loves calm, placid freshwater spans, flourishing in lakes, reservoirs, and quarries.


Are they dangerous?

Just be glad you're not a plankton. Although sowerbyi hunts by stinging its prey with poison, their wee stingers are pretty unlikely to penetrate human flesh. Even if they managed to put a dent in you, their wee poison wouldn't do much either.


Where do they come from?

Sowerbyi originally came from China, and came to North America by 1880, probably by tagging along with ornamental aquatic plants. Until now, there had been no confirmed sightings in Manitoba, North Dakota, Saskatchewan or Alberta; likely, the cold kept them away. Some theorize that Southern Manitoba's recent heat wave may have triggered cold-resistant sowerbyi polyps -- which can long dwell undetected -- to bloom into a whole colony of grown-up jellyfish.


-- Melissa Martin

Republished from the Winnipeg Free Press print edition August 30, 2010 A4

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