Jellyfish Updates

1 Response to “Jellyfish Updates”

• shan

  24/10/2008 at 13:25

  Living World / Unusual Organisms
  Do Jellyfish Rule the World?
  The brainless blobs are booming. All scientists know is it isn’t good.

  by Thomas Mallon
  published online September 13, 2007

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  Red Lobate ctenophore
  Image Kevin Raskoff © 1999 MBARI
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  A scientist doesn’t often fret that his research subjects might clog the ventilation system of his office. But Chad Widmer, 37, a senior aquarist at the Monterey Bay Aquarium just south of San Fran­cisco, studies jellyfish, and along the world’s coasts, jellies seem to be exploding in size and number, pulsing through waters they haven’t ventured into before. In places like the Gulf of Mexico—where 60-pound blobs with 80-foot tentacles have appeared in recent years—the increasingly abundant creatures provoke mostly fear and disgust. To Widmer, though, everything about the jellies is fascinating. (He has a crystal jelly, the Aequorea victoria, tattooed on his left leg.) He especially wants to be able to predict their “blooms,” sudden spurts in the jelly population that can wreak havoc on fishermen’s nets or snarl a building—like the Monterey Bay Aquarium—whose operations depend on running seawater through it.

  The aquarium stands on a part of the waterfront where John Steinbeck famously described boats brimming with fish. Within a decade of Cannery Row’s 1945 publication, though, the bay had been emptied of silver sardines, and now, a half century later, amid the jellyfish boom, something dire is happening to the bay once more. Over the past several years, Widmer says, salmon catches have “gotten worse and worse and worse,” while leatherback sea turtles, in order to find their food, have had to go “farther and farther offshore.” And the mola, a large sunfish that was once so abundant in Monterey Bay? “They’re just not here,” Widmer says. At first glance, even jellyfish would seem to be vanishing; in recent years the creatures have been more or less disappearing from the bay’s surface. Look deeper, though, and you’ll find a staggering diversity of these spectacular, tentacular creatures.

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  Along with the worries comes a rich set of scientific questions: Does the rise of the jellies (pdf) have something to do with the decline of the fish? What can jellyfish tell us about the health of the oceans? How will they fare as the oceans absorb more carbon dioxide from the air and become more acidic? Right now, no one knows. Across town at Monterey Peninsula College, Kevin Raskoff, who has investigated jellies in the Arctic, argues that for all their abundance, they are “probably the most alien life-form on the planet.” He still sees the animals as being, to a great extent, “a big black box. We know they’re there, but we don’t necessarily know what they’re doing.” Yet everything we have managed to learn about jellies in recent years “keeps pointing to how much more important they are than we thought,” Raskoff says. “There’s a long history of jellyfish really coming into huge numbers, big blooms, with a big effect on ecology, when you have perturbations to the system.” While perturbations can be part of a natural cycle, humans have been jostling the ocean ecosystem with dismaying gusto. We’ve been overfishing tuna and swordfish—some of the jellies’ predators—and the jellies seem to be responding.

  At the Monterey Bay Aquarium Research Institute (MBARI), founded in 1987 by computer pioneer David Packard, veteran scientist Bruce Robison isn’t ready to make a primary-level link between jelly increases and global warming, but he’s certainly intrigued by the “second-, third-, or eighth-level connections.” Jellies, he says, “show us how the seas are changing, both naturally and in response to our own meddling.” We may not be putting jellies in charge of the oceans, but “we are giving them their shot at playing a bigger role by wiping out much of their competition,” he says. It’s their “broadly adaptable physiology” that will allow them “to outcompete more complicated animals for niches that become available because of warming, or acidification, or any number of reasons.”

  So don’t blame the jellies. However many intake valves they clog or swimmers’ legs they sting, jellies aren’t turning the oceans acidic or warming them up. We are.

  Jellyfish are not fish at all. They lack brains and spines, and yet they seem to exhibit a curious superiority, generating their own light and taking on guises almost ridiculously beyond classification. Siphonophores are jellyfish linked together to form what look like weaponized space platforms, while among the discrete medusae, moon jellies can appear both vegetal and artificial—purple pansies trapped under gauzy, throbbing petticoats. Brainless and bloblike though they may be, jellyfish “make a lot of different choices,” Widmer says: to seek the light or the dark; to spawn or not to spawn. They can sense food—zooplankton or fish larvae—in the distance and then cast out their tentacles to catch it.

  Any scientist hoping to study jellies must reckon with a distinct set of obstacles. The creatures are too fragile to tag and monitor, so it’s hard even to know how long they live. Some probably last only several weeks, though Widmer has managed to keep a cohort of moon jellies alive for more than five years in one of the aquarium’s tanks. Only in the past two decades has what he calls “a revolution in collection techniques”—involving manned and remote-operated submersible vehicles—allowed researchers to bring intact specimens, instead of undifferentiated goo, back to their labs.

  Yet for all that can be learned there, how much better it would be to know how jellies live and breathe, not in the glass tanks of human laboratories but in the ocean, where they actually reside. Knowing how much oxygen they use, for example, would indicate how much energy jellies require, how much prey they need to consume, and thus how big a player they are in the underwater food web.

  To learn just how much jellies breathe in their native habitat, scientists from MBARI are setting off this morning in the Point Lobos, one of the institute’s three research vessels. Leading the team is Robison, a native Californian who still bears traces of his surfer-boy youth beneath the lines of weathering. He has watchful blue eyes, an easy, cackling laugh, and an undiminished enthusiasm for the work he’s been doing for more than three decades.

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