Back in my younger days, I worked a brief stint in the men’s department of Macy’s. I quickly bonded with one of my co-workers, and our giggle-fests ultimately got us both fired – much to our joy. I first noticed him when he was standing near me during a one-day sale and there were throngs of bargain-hungry customers. He said “Look! They’re swarming!!” Since then, the word “swarm” has always cracked me up.

After reading an article published recently in the New York Times, the word is no longer very funny. In the context of jellyfish swarms, the word is a very serious indicator of the health of the ocean. It means that ecosystems are way out of balance. The predators that normally feed on jellyfish are declining due to overfishing, which allows jellyfish species to quickly proliferate. Predators of jellyfish are reduced as are fish species that normally compete with jellyfish for food such as phyto- and zooplankton.

Now, they’re terrorizing tourists and beachgoers as they appear en mass near beaches where they were once rare. The sting of jellyfish-swarms are a problem; but the real problem is far larger. In addition to overfishing of jellyfish predators and imbalanced ecosystems, rising sea temperatures are contributing to jellyfish overpopulation because they prefer warm waters for breeding. Oxygen-depleting pollution in coastal waters is a problem for most marine species that cannot survive in “dead zones.” Jellyfish, often referred to as the cockroaches of the sea (though much more aesthetically pleasing in my opinion!), have no problem living in oxygen-depleted waters.

The scientific community does not agree on whether jellyfish swarms are a red-flag for ocean health. The cause, in my lay-opinion, is likely due to human activity. More research is needed to determine why jellyfish are “swarming” in some areas and not in others, but it’s not a good sign.