Jellyfish blooms can emerge when their predators are reduced because of commercial fishing, or when low levels of dissolved oxygen chase off competition for food, allowing more jellyfish to thrive. They also appear to surge around undersea structures like oil rigs and wind turbines, which give their budding young more places to latch onto and grow.
But while spikes in jellyfish clusters, known as blooms, have wreaked havoc in some circumstances, fears that rising numbers of jellyfish are taking over the oceans “are probably a myth,” said Rob Condon, an oceanographer and marine scientist who studies the species.
“It’s more likely that we’re interacting more with them in their backyard rather than them being in our back yard,” he said.
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Condon started the Jellyfish Database Initiative, which compiles current and historical data on the creatures. Its data suggests jellyfish populations wax and wane in 20-plus year cycles, the last of which peaked more than a decade ago. He’s now the executive director of the Young Scientists Academy, a nonprofit that tries to foster interest in science among students, some of whom are helping update it now.
“Since about 2005 or 2006 we’re actually going through a declining phase in the cycle,” he said. “We’re about to hit another rising phase. So partially, those claims that jellies are increasing are correct — you’ve just got to get the right time period.” And with more people living and working on the coasts or offshore, “We’re going to experience these type of encounters more.”
While cyclical jellyfish blooms appear to be a global, natural phenomenon, Gershwin said populations can surge in some areas that have been “highly disturbed.”
“We’re taking out their competitors. We’re giving them warmer waters where they grow faster and reproduce faster. We’re giving them coastal construction that’s giving their polyp stages more room to live and grow their colonies,” she said. “We’re doing a whole lot of things that are giving them conditions they’ve never known in half a billion years. They’ve never had it so good.”
But consuming large numbers of jellyfish in response “just opens up eco-space for the next pest in line,” she said. “It doesn’t really solve the problem of why pests are getting into super-abundances.”
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Condon said Pedersen’s process sounds “kind of cool,” even though he’s not personally enthusiastic about the taste of jellyfish in general: “It’s okay. It’s something you should experience, I guess.”
But he said a process that fast-tracks the consumption of jellyfish should be subjected to further study to make sure they can be harvested sustainably. Jellyfish aren’t just pests. They’re the entire diet of leatherback turtles, they’re a major food source for some species, and their trailing tentacles are “almost a little microhabitat” for smaller marine life. Medical researchers have also used glowing jellyfish proteins to track genetic changes and fight diseases like AIDS.
And Pedersen said while her research may yield gastronomic benefits, she doesn’t see it as a magic bullet for fears of a jellified ocean.
“I don’t think we save the world by eating jellyfish crisps,” she said. “But I know there is a big discussion about the different kinds of jellyfish problems around the world, so it makes sense that we could eat some of them.”
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