Unwanted visitors of the gelatinous kind are making their way to Nova Scotia waters, spooking some swimmers who have come across potentially lethal Portuguese man-of-war that have travelled far from their tropical homes.
Bethany Nordstrom, a biology student at Dalhousie University who is researching jellyfish, said Tuesday that she has had five confirmed sightings of Portuguese man-of-war so far this summer, raising questions about their unusual presence in northern waters.
“They prefer tropical and subtropical waters, so they don’t usually end up in our waters unless it’s a windy, stormy summer,” she said. “They’re very much affected by wind and tide and currents because they don’t have a way to move on their own … these guys just go by the wind.”
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She said man-of-war don’t have a jellyfish’s classic bell shape that pulses water in and out, allowing them to move on their own. Instead, they have a flotation device like a balloon that holds them above the water and are moved by the currents, while their tentacles drag beneath them.
They are mostly transparent, but have accent colours of bright pinks, blues and purples, with tentacles that can reach nine metres in length.
“It’s kind of like an iceberg – you see this little float on top that is maybe the size of your hand, but everything that is going to do the damage is underneath the water,” she said.
They have been spotted in the Bay of Fundy and around the Scotian Shelf before, but perhaps not in such numbers as being reported this summer.
Nordstrom said strong winds and currents likely pushed the colourful species into areas around Crystal Crescent, a popular beach outside Halifax, where people have seen the colourful creatures lolling on the sand.
Amy Clark was with her family at the beach last week when one of them spotted what they thought was a small toy floating in the water. She said a wave then washed it ashore, leaving it at their feet.
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“It was beautiful – it literally looked like when you blow a bubble,” Clark told CTV News. “It was see through, it was iridescent. It caught the light beautifully.”
She said they did some research after burying it in the sand and determined it was a Portuguese man-of-war, prompting them to warn others on Facebook.
Nordstrom said most of the sightings have been near the beach, but one was spotted out in the water on the south shore in late June.
The man-of-war, which are siphonophores rather than jellyfish, have stinging cells that act like a little harpoon and can inject a venom into anything that runs into them.
She said the creatures can be deadly for people who are allergic to their venom, but that most will just suffer a “very, very painful” sting that can last for hours.
Nordstrom said she’s trying to determine if changes in water temperatures are affecting the presence of jellyfish, which are a main food source for endangered leatherback turtles, and other creatures like the Portuguese man-of-war.
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“I would like to see if there are changes like that happening,” she said from her lab. “I think it’s becoming more and more important to start monitoring species like that to see if that is going to be a problem in the coming years.”
She has been gathering data on lion’s mane jellyfish with the help of about 50 citizen scientists. She received about 300 individual emails last year from people who spotted jellyfish and is on track to receive about the same this year.
She’s hoping anyone who sees a Portuguese man-of-war or jellyfish takes a picture and emails it to her at jellyfish@dal.ca.