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A Blue View: Jellies - Oceans Out of Balance

by John Racanelli, Chief Executive Officer

Published August 14, 2013

A Blue View is a weekly perspective on the life aquatic, hosted by National Aquarium CEO John Racanelli.

From the smallest plants and animals invisible to the human eye to entire ecosystems, every living thing depends on and is intricately linked by water.

Tune in to 88.1 WYPR every Tuesday at 5:45 p.m. as John brings to the surface important issues and fascinating discoveries making waves in the world today.

August 14, 2013: Jellies - Oceans Out of Balance

Click here to listen to John discuss how the rapid increase in jellyfish populations has negatively impacted the health of our oceans.

Beautiful, eye-catching, and otherworldly, jellyfish are dazzling creatures to look at, though not something you want to run into at the beach.

Not technically fish, jellies have drifted through our seas for more than 500 million years. They range in size from that of a pinhead to more than 8 feet in diameter, with tentacles 130 feet long. Most species have tentacles that sting, even when they become detached from the jelly’s body. And, as many a beach-goer can attest, those stinging cells can make for some less than pleasant experiences when our paths accidentally cross.

Related to sea anemones and corals, jellies have no heart, brain, blood, or bones, and are 95 percent water. Contrary to popular myths, jellies are not out to get you. As ocean drifters, they are carried along on ocean currents. But their vast numbers in certain places have made them a menace, and their unique ability to thrive in less-than-ideal conditions has scientists keeping a close eye on these fascinating creatures.

Jellies seem less susceptible to algae blooms, pollution, warming waters, and reduced oxygen levels, meaning that the more the environment deteriorates, the better it is for jellies. In an alarming phenomenon dubbed “jellification” by some scientists, jellies in some areas of the world are literally taking over the seas.

The role of jellies in the ocean ecosystem and whether or not their increasing numbers are displacing other ocean inhabitants are both matters of active debate in the marine science community. There are several reasons attributed to the rise of jelly populations. In addition to their ability to thrive in inhospitable conditions, jellies benefit when the fish, turtles, and other species that normally eat them are overfished. Then, as jellies eat zooplankton, fish eggs, larvae, and even fish, they further impact the food chain, perpetuating an imbalance that’s difficult to correct.

An overabundance of jellies isn’t good for tourism around the globe, particularly when they wash up on beaches. Depending upon the species, a jellyfish sting can cause anything from mild discomfort to severe pain and in rare cases, like the box jellies of Australia, even death. Jellies also affect fisheries—and fisherman—when they collide with nets, sometimes even killing the catch with their toxins. Jellies can also cause power outages and equipment damage at power plants by clogging cooling intakes.

Considered a delicacy in China, some see dining on these unique creatures as a creative and efficient way to control the jellyfish population. The European Union has embarked on an international research program to evaluate the spread of jellies in the Mediterranean and other regions and develop a coastal management strategy accordingly.

For all the issues that jellyfish blooms can cause, they are essential and active participants in the ocean ecosystem. They belong there. The best way you can keep bays and oceans healthy is to make smart choices at home. One important place to start is in your yard. Avoid over-fertilizing your lawn and garden. Excess fertilizer washes into our waterways, reduces oxygen, and contributes to harmful algae blooms—conditions that are great for jellies but terrible for fish populations. You might even consider opening your mind to a new delicacy when jellies show up on a restaurant menu near you.

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