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In the increasingly damaged sea, one animal is thriving

August 3, 2016 at 6:10 PM EDT
Climate change, overfishing and pollution would naturally seem harmful for marine life. But one group of animals appears to be thriving: jellyfish. The blob-like creatures reproduce rapidly in higher temperatures and can prosper in waters tainted by human activity, such as the Gulf of Mexico’s oxygen-depleted “dead-zone.” Plus, declining fish populations mean reduced competition for food.
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GWEN IFILL: It’s that time of year when many folks are heading to the beach. But along parts of the southeast coast, vacationers may run into some unwanted visitors, as the National Weather Service has issued hazard warnings caused by jellyfish found in Myrtle Beach, South Carolina.

That’s temporary, but what’s not are the persistent numbers of the slimy creatures populating the waters of the ocean.

Science correspondent Miles O’Brien reports, just in time for the summer, for our weekly series on the Leading Edge of science and technology.

MILES O’BRIEN: On beaches, in harbors and beneath bays all over the world, jellies are on a roll. And it appears it’s a stinging rebuke of us from Mother Nature herself.

JENNY PURCELL, Western Washington University: Jellyfish are thriving in environments that are damaged by the human activities.

MILES O’BRIEN: Marine biologist Jenny Purcell is a research associate at Western Washington University in Bellingham. She studies huge aggregations, or smacks, of moon jellyfish that have exploded in Puget Sound.

JENNY PURCELL: Human populations have increased. Their pressure on the oceans have increased. And the jellyfish populations have increased. So it’s very hard to put a cause and effect on that, but the correlations are certainly there.

MILES O’BRIEN: There is plenty of anecdotal evidence that it’s happening, but arriving at hard numbers is like nailing jelly to a wall.

JENNY PURCELL: Because there have been so few jellyfish scientists, there’s a critical shortage of jellyfish data. We don’t know how many jellyfish or even what jellyfish are there.

MILES O’BRIEN: But at aquariums all over the country, there is plenty of concrete proof jellyfish fascinate us.

CHILD: Cute, but dangerous.

MILES O’BRIEN: They are nature’s lava lamp, a morbidly mesmerizing marquee attraction.

STEVEN BAILEY, New England Aquarium: Penguins, hard to beat penguins.

MILES O’BRIEN: Yes.

STEVEN BAILEY: Sharks, hard to beat sharks. But I would say that jellies come in a strong third rather consistently.

This is hour cold culture room.

MILES O’BRIEN: Steven Bailey is the curator of fishes at the New England Aquarium, smack dab on Boston Harbor, if you will. Bailey is a card-carrying jellyhead.

STEVEN BAILEY: They seem to be capable of doing things physiologically that can’t be described by their body plan, by the structures that they possess.

MILES O’BRIEN: This got me intrigued.

CHRIS DOLLER, New England Aquarium: This is actually the fifth floor of the aquarium, considered, like, sort of the attic.

MILES O’BRIEN: So I asked senior aquarist Chris Doller for a behind-the-scenes tour.

Where are we now?

CHRIS DOLLER: This area is affectionately known as Area X.

(LAUGHTER)

MILES O’BRIEN: Area X is the one of the most prolific jellyfish nurseries in the nation. They keep about 13 at the aquarium, a varied sampling of the 200 large and 800 small types of jellyfish in the world.

They are all cnidaria, in the same phylum as anemones and corals among others.

CHRIS DOLLER: They’re so simple, yet so complex. There’s a huge variety of jellies. So, you can get very colorful jellies. You can get very iridescent jellies. We have some fluorescent jellies.

MILES O’BRIEN: No brain, no blood, no spinal cord, just muscle, nerves and stinging cells to kill prey, and inadvertently bother beach-loving humans.

How often do you get stung?

CHRIS DOLLER: I try not to, but it’s almost a daily occurrence.

MILES O’BRIEN: So what does a grizzled pro use? Warm water or vinegar.

CHRIS DOLLER: I think the worst sting I ever got was from a flower hat jelly.

MILES O’BRIEN: Really?

CHRIS DOLLER: Yes.

MILES O’BRIEN: Some jellies bear more than a resemblance to a plant. The lagoon and upside down jellyfish species are among those that are photosynthetic. Their tissue becomes a home for algae, and the jellies use it for energy. All they need is sunshine to stay alive.

CHRIS DOLLER: That brown that you see in the tissue, that’s all algal cells, so they are basically harvesting within them. Yes, the plant is sort of living in their tissue.

MILES O’BRIEN: Jellyfish reproduce sexually and asexually. Most adults send sperm and eggs into the water, creating small larvae that grow into polyps. They reproduce by cloning over and over and over again.

Voila, a jellyfish smack.

They’re not schooling in the classic sense, right?

CHRIS DOLLER: Right. The way they bud off, it’s just pure numbers, and then they’re all sort of drifting in the same current. They don’t migrate intentionally. They just sort of go where the ocean takes them.

MILES O’BRIEN: They go with the flow.

CHRIS DOLLER: Go with the flow.

MILES O’BRIEN: On the move, they are constantly grazing. So why are they thriving?

Many jelly species reproduce faster in warmer water, so climate change has an impact. But, right now, researchers say overfishing is the biggest cause of the jellyfish bonanza.

JENNY PURCELL: People have fished out the fisheries. There is more food left for the jellyfish.

MILES O’BRIEN: And they will eat almost anything. They also don’t mind living in troubled waters, like the huge oxygen-starved Dead Zone in the Gulf of Mexico. It is caused by nutrient-rich fertilizer flowing down the Mississippi.

It creates a lot of algae that depletes underwater oxygen levels. That means fewer fish and more food for the jellies. So, algae blooms and jellyfish smacks go hand in hand.

The guy who has that perfect lawn right down to the river, if you will, when he goes to the beach and he gets stung by a jellyfish, he actually has some culpability.

STEVEN BAILEY: I would say that that’s rather poetic, yes.

MILES O’BRIEN: Maybe one solution is to start eating them more. In Florida, Georgia and the Carolinas, a new kind of fishing industry is emerging. Entrepreneurs are harvesting cannonball jellies, pickling them, and exporting jelly balls to Asia, where they are considered a delicacy.

Have you ever eaten a jellyfish?

CHRIS DOLLER: I have.

MILES O’BRIEN: How is it?

CHRIS DOLLER: Didn’t enjoy it.

MILES O’BRIEN: Really?

No surprise. They have no taste, are as chewy as an eraser, and pack precious little caloric value. I guess that means we can eat a lot of them, if we like. But there is little concern we might fish these guys into oblivion.

JENNY PURCELL: I think the jellyfish will persist after the Armageddon.

(LAUGHTER)

MILES O’BRIEN: They started on Earth more than 500 million years ago, so why not go for a billion? The cockroaches of the sea, perhaps, but in the smackdown for fans, the jellies win, tentacles down.

Miles O’Brien, the “PBS NewsHour,” Boston.

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