Jellyfish cause problems beyond stinging swimmers. Cooling systems that use cold water pumped from the ocean are vulnerable to being clogged by swarms of jellyfish. Mother Jones rounds up an impressive list of such cases:
"Jellyfish blooms—the term for giant swarms of jellyfish—have also been responsible for nuclear shut downs in California, Florida, Israel, Scotland, India, and Japan, where one plant has reported removing as much as 150 tons of jellyfish from its system in one day. In 1999, a jellyfish bloom clogged the cooling system of a major coal-fired plant in the Philippines, leaving 40 million people without power. And in 2006, in a nigh unprecedented act of aggression, jellyfish in Brisbane, Australia, afflicted the massive nuclear-powered USS Ronald Reagan with an "acute case of fouling," clogging its cooling systems and forcing it to leave the harbor."
To address the issue of jellyfish blooms, engineers at the Korea Advanced Institute of Science and Technology have built self-propelled robots that chop up jellyfish in the water. Imagine an underwater mulcher.
Below is a video of one of the robots shredding jellyfish. Don't watch if you don't want to see jellyfish being shredded.
Lead by Prof. Hyeon Myeong, the research team and has been testing the robots in Gyeongnam Masan Bay. The institute's website has more details about the project, which is called JEROS:
"JEROS uses its propulsion speed to capture jellyfish into the grinding part on the bottom, which then suctions the jellyfish toward the propeller to be exterminated.
The field test results show that three assembly robots operating at 4 knots (7.2km/h) disposes jellyfish at the rate of about 900kg/h."
For the sake of this post, I'm sidestepping the issue of whether or not killing jellyfish is ethical. However, I would like to ask some questions about other issues related to shredding jellyfish.
Is the jellyfish population really a growing problem?
A number of scientists warn that despite the media attention surrounding jellyfish blooms, there's a lack of historic data on jellyfish populations. However, the Jellyfish Database Initiative, in collaboration with the National Center for Ecological Analysis and Synthesis is working to collect such data.
The debate over the "jellyfish joyride" is as contentious as I hope the comment section on this post will be. Some biologists argue that there is nonetheless a need to manage and reduce jellyfish populations in ecosystems that have seen negative impacts associated with blooms.
Is shredding biologically sound?
Biologist Rebecca R. Helm, who studies jellyfish, wrote a fascinating post on why the JEROS is a bad idea. Not only will the machines leave tons of dead jellyfish tissue floating around in the ocean, it may even provoke artificial fertilization in some species. This could lead to the exact opposite of the intended result:
"Assuming you rip through 6000 jellies per hour for 12 hours, you’ve now released SEVENTY TWO THOUSAND jellies worth of eggs and sperm into the water all at once, rather than slowly over time. And where are those embryos going to go? They’re going to the sea floor to metamorphose into polyps, in stressful conditions that are now great for them and terrible for everyone else (thanks to all the dead biomass floating around) and they’re going to multiply. Jelly polyps can live for years, and can clone themselves. One polyp can produce hundreds of clones, and each clone can produce hundreds of jellies."
Does shredding address the cause of the problem?
What we do know is there are some very hearty species of jellyfish, that can survive in waters that are increasingly warm and acidic. Overfishing has been pointed to as another factor that has enabled jellyfish blooms. The conditions that could lead to a growing jellyfish population and growing jellyfish problems are also bad for the ocean's biodiversity in general. Of course, addressing problems like global warming is considerably more difficult than killing off thousands of jellyfish.