Wassup with jellyfish?

in Technical Issues by Admin — August 3, 2009 at 6:00 am | 3 comments

 

Editor’s note:

Accounts of recent dramatic increases in jellyfish populations in the Gulf of Mexico, including exotic species, raise questions about causes for and effects of this phenomenon. For example, check out “Blobs of summer.” 

Jellyfish are grouped into two major taxonomic groups (phyla): Cnidaria and Ctenophora, the former with tentacles and stinging cells, the latter without – and both pronounced with silent “c’s.” 

Jellyfish feed on the eggs and larvae of important fishery species and they clog shrimp nets. On the other hand they are eaten by crabs and sea turtles, for example.

A prospective population explosion of jellyfish carries unpredictable fishery implications for the northern gulf coast but collecting and studying them is problematic, for obvious reasons. Anyhow, I was inspired to post some thoughts about these ephemeral creatures that I find both intriguing and perplexing. 

BTW, from a coastal science perspective the term jellyfish is not inherently pejorative but from a political standpoint  jellyfish is an apt descriptor for spineless coastal decision makers!

I became fascinated with jellyfish at the age of ten, during a two-week sojourn in 1950 at a YMCA camp on the western shore of the Chesapeake Bay near the Calvert Cliffs, sheer bluffs that contain* a mother lode of sixteen million-year-old Miocene fossils, including foot-long oyster shells. When I was there fresh chunks of the cliff face were constantly falling onto the beach. We campers distracted ourselves from homesickness by searching these post-dinosaur, pre-hominid “zoology archives” for the fossilized teeth of gigantic long-extinct sharks – teeth that ranged up to five inches in length! 

Another zoological distraction for us “Lord of the Flies wannabees” was to carefully pick up live jellyfish littering the beach with our pre-calloused hands and then patting our freshly jellied palms against the nape of a victim’s formerly lily-white but now sun-reddened neck.** This caused the victim pain and itching that was curiously hilarious to the perp and it’s one of the zoological memories that contributed to my lifelong fascination for jellyfish and other spineless sea creatures.

The jellyfish weapon for this sting-inducing pastime was the ubiquitous and notorious Atlantic sea nettle Chrysaora quinquecirrha, the animal that makes summertime swimming a miserable experience throughout most of the Chesapeake estuary. This animal has the consistency of Jello with no solid parts, so, although the fearsome 30 ft sharks and nettles swam together, only the sharks left their mark at Calvert Cliffs. On the other hand, the nettle continues to get the last sting!

Purely for the psychological benefit of our concerned parents, the camp administrators had installed “placebo” fencing to form a “nettle-free” swimming area. In reality, tidal and wind driven currents swept the jellyfish against the nettle-shredding netting, allowing free passage of tentacle fragments as painful to the skin as the intact jellyfish outside the fence.

Eight years later at the University of Maryland I sampled engineering and English, then settled on zoology as a major. My mostly pre-med classmates invariably studied the vertebrates, but I was drawn to the richly diverse and highly mysterious invertebrates.

This choice eventually led to a job as an oyster biologist at the Solomon’s Island research lab run by the University of Maryland, where I met John Bishop, a professor on sabbatical from the University of Richmond who was studying the common Chesapeake Bay ctenophore known as the sea walnut (Mnemiopsis leidyi). This is a non-stinging jellyfish that emits beautiful explosions of blue light in boat wakes at night. I became Bishop’s friend and Masters student, before continuing on in grad school to study oyster reef communities in Georgia.

Our anthropomorphic bias toward animals with backbones makes us forget that invertebrate critters far outnumber and outweigh us in the biosphere. Termites comprise a huge proportion of terrestrial animal biomass and I suspect that jellyfish may be analogous in the marine world but no one really knows how plentiful they are. I once set out on a quest to help solve this mystery. 

Around the year 1982 I was an associate professor at LSU on a research trip to the Laguna del Terminos, a beautiful mangrove-dominated estuary on the southern gulf coast of Mexico – due south of New Orleans. I had brought along the prototype of a crude invention that I had fabricated to count ctenophores in open water. My device consisted of a 3 ft long piece of 3 inch diameter PVC pipe fitted on the front end with a plastic funnel like the shields used to prevent dogs from scratching their newly-clipped ears. A Radio Shack phototube and electronic counter were supposed to be the “brains.”

My concept was that if this device were slowly towed from the deck of a research vessel the fragile ctenophores would pass single file through the tube and each would bioluminesce (light up) as they brushed against the inner surface. Each flash would be counted and (voila) the flashes per swept volume could be computed.

The test run didn’t use a boat however. It involved carrying my device into the Laguna del Terminos around midnight in my undershorts after imbibing multiple Dos Equis cervezas with my fellow “researchers.” I waded along the shoreline in waist deep water pulling my invention.

Unfortunately for the future of jellyfish science, the test was an utter failure but, based on their gales of laughter, my witnesses clearly enjoyed watching. These critics included Mike Kemp, a coastal scientist at the University of Maryland (featured here on YouTube) who recently reminded me of the auspicious event.

Despite the questionable performance of “Ctenophorometer I” that ended up in a Mexican landfill I remain confident that a similar device fitted with modern electronics would be successful.

In closing, I call your attention to a July 30 story on National Public Radio’s Morning Edition that described possible effects on climate change by the world jellyfish population.

Len Bahr

*Unfortunately, since my time there the Calvert Cliffs became the construction site for Maryland’s only existing nuclear power plant, which destroyed much of the formation and discourages visitors and collectors.

**This was four years before Brown v. Board of Education and south of the Mason-Dixon line, so there were no campers of color (and I suppose no Jews) in this Christian-theme camp. My cabin counselor (Leonard Neil) was a nice guy who it would have been interesting to contact for this post but many years ago my late mother Florence Riefle Bahr sent me a clipping from the Baltimore Sun reporting that he had died young.