Around the globe, fish populations are declining while the number of jellyfish is exploding. Climate change may be “turning back the clock to the Precambrian world, more than 550 million years ago, when the ancestors of jellyfish ruled the seas,” writes Yale Environment 360. Bow down to our future gelatinous overlords:
The world’s oceans have been experiencing enormous blooms of jellyfish, apparently caused by overfishing, declining water quality, and rising sea temperatures. Now, scientists are trying to determine if these outbreaks could represent a “new normal” in which jellyfish increasingly supplant fish.
The Nomura’s jellyfish is a monster to be reckoned with. It’s the size of a refrigerator and can exceed 450 pounds. For decades the hulking medusa was rarely encountered in its stomping grounds, the Sea of Japan.
Then something changed. Since 2002, the population has exploded six times. In 2005, a particularly bad year, the Sea of Japan brimmed with as many as 20 billion of the bobbing bags of blubber, bludgeoning fisheries with 30 billion yen in losses.
Why has the Nomura’s jellyfish become a recurring nightmare? The answer could portend trouble for the world’s oceans. In recent years, populations of several jellyfish species have made inroads at the expense of their main competitor — fish — in a number of regions, including the Yellow Sea, the Gulf of Mexico, and the Black Sea. Overfishing and deteriorating coastal water quality are chief suspects in the rise of jellies. Global warming may be adding fuel to the fire by making more food available to jellyfish and opening up new habitat. Now, researchers fear, conditions are becoming so bad that some ecosystems could be approaching a tipping point in which jellyfish supplant fish.
“When an ecosystem is dominated by jellyfish, fish will mostly disappear,” says ecologist Sun Song, director of the Institute of Oceanology in Qingdao, China. “Once that happens,” he contends, “there is almost no method to deal with it.” Just think of attempting to purge the Sea of Japan of billions of Nomura’s jellyfish, many of them hovering meters below the surface and therefore invisible to satellites or the naked eye. Total jelly domination would be like turning back the clock to the Precambrian world, more than 550 million years ago, when the ancestors of jellyfish ruled the seas.