Jellyfish Gone Wild — Text-only | Flash Special Report
HOME TO “THE SLIME BANK”
Nicknamed “America’s Bread Basket,” the Bering Sea produces more than fifty percent of the U.S.’s entire catch of fish and shellfish. But now the long tentacles of environmental change are wrapping around this important fishery.
How? By expanding the range and increasing the size of the Bering Sea’s jellyfish population. The problem? Jellyfish compete for plankton food with pollock, an important commercial fish, and may consume young Pollock.
THE RISE AND FALL OF BERING SEA JELLYFISH
Starting in the 1990s:
Bering Sea jellyfish began fanning out north and west from the Alaskan Peninsula. “We began finding thick concentrations of jellyfish in places where we had hardly seen jellyfish before,” says Lorenzo Ciannelli of Oregon State University.
The size of the jellyfish population in the eastern Bering Sea soared by ten-fold, eventually peaking at record levels in about 2000.
During this period, one area north of the southeastern Alaskan Peninsula became so jellified that fishermen nicknamed it “the Slime Bank” and began avoiding it altogether for fear of tangling their nets in wads of tentacles.
After 2000, the Bering Sea’s jellyfish population downsized, eventually stabilizing at moderate levels that still exceed the relatively low numbers of the 1980s.
THE CAUSES OF JELLIFICATION
Scientists suspect that many factors are influencing the ups and downs of the Bering Sea’s jellyfish population. For example, the annual harvesting of more than one million tons of pollock may increase the availability of plankton food for jellyfish.
In addition, sea temperatures, which have increased since 1990, may be promoting jellyfish reproduction and expanding jellyfish ranges northward. Nevertheless, because temperatures continued to climb as jellyfish populations declined after 2000, scientists believe that--no matter how much temperatures rise--there may be a finite number of jellyfish that the Bering Sea can support.
AN ALL-POINTS-BULLETIN FOR POLYPS
Ciannelli suspects that jellyfish expand their ranges by colonizing new areas as polyps--a developmental phase during which they live as tiny transparent organisms clinging to the ocean floor. But no one knows where the Bering Sea’s elusive polyp colonies are located.
Ciannelli’s research team is currently attempting to find them via computer simulations that recreate the release and drifting of young jellyfish from suspected polyp habitats. These analyses are designed to help scientists identify the locations of cyber polyp colonies that seed cyber swarms resembling real-life jellyfish swarms. Then, the real-life locations of these cyber polyp colonies can be studied further, perhaps eventually by undersea robots. “To really understand the Bering Sea’s jellyfish, we just have to find those polyps,” Ciannelli says.
Ciannelli’s research team includes Mary Beth Decker of Yale University, Kung-Sik Chan of the University of Iowa and Carol Ladd of the National Oceanic and Atmospheric Administration.
Sea nettle populations in the Bering Sea may be increasing and expanding because of climate change. The tentacles of the northern sea nettle extend almost 20 feet. Credit: Photo by Kevin Raskoff
Jellyfish populations peaked in 2000. They have since moderated at levels that still exceed those of the 1980s. In addition, jellyfish ranges have expanded. Credit: Zina Deretsky, National Science Foundation, after Brodeur et al in "Progress in Oceanography"