Dive Dry with Dr. Bill

#457: Drift Away!

Three recent events have coincided to formulate the topic for today's column. I received an e-mail from a doctoral candidate in New Zealand who was studying the genetics of a nudibranch (shell-less snail) I'd encountered in some of my very early research. Then I did two dives with Dave and Sue from Indian Valley Scuba and encountered a variable starfish that also played a role in that research. Finally, I was at karaoke down at the El Galleon when some "youngsters" (aren't they all these days... sigh) sang one of my all-time favorites, Dobie Gray's rendition of "Drift Away."

Yes, I know... you are scratching your heads wondering just what connection these three events might have. It's all in my mind... or should I say the experiences in my particular (or is it peculiar?) journey through time and space. I arrived on Catalina August 24, 1969, excited about diving in kelp forests and teaching marine biology on SCUBA to my students at the old Catalina Island School for Boys (Toyon Bay). Being new to the West Coast, I had a lot to learn before I could teach effectively... and I'm still learning today (sometimes just relearning what I've forgotten over the years!). I maintained contact with one of my mentors at Harvard, Dr. H. Barraclough Fell, a noted expert on echinoderms (starfish, sea urchins, etc.). We talked about doing joint research under his National Science Foundation grant.

Barry had studied marine life drifting on logs drifting off the coast of New England to see if they could disperse critters to new locations that way. Back in New Zealand he had analyzed unusual sea urchin finds atop deep seamounts in the ocean, and concluded that these sea urchins had drifted there from thousands of miles away by riding on detached kelp plants. Knowing my interest in kelp, Barry suggested I study the marine critters found on rafts drifting in our waters. Our hypothesis was that marine life from other regions where kelp existed could drift out to Catalina in its early days and help colonize the island's newly created shoreline. Over time these travelers could continue to bring new genetic material to the populations already on Catalina. In addition, "kelp rafting" could bring species in from other regions such as north of Pt. Conception (a different biogeographic zone) or from south of the border.

Barry and I carried out this research for 7 1/2 years until his interests shifted to studying the exploration of the Americas by cultures prior to Columbus' "discovery" of the New World. In 1976 he published America BC in which he proposed that inscriptions found on rocks and other objects in the Americas represented writings from ancient Old World cultures that visited the Americas long before Columbus was born. Back then his work was largely dismissed by critics who claimed the only prior contact with the New World was by the Norse. Since then much has been discovered that suggests many cultures from the East and the Far East (West?) may have "discovered" the Americas before Columbus' voyage (but after its colonization by the early Native Americans who truly were the first to discover it). I recently "discovered" Clive Cussler and smiled while reading his book The Navigator which mentioned Barry's name in a discussion of possible ancient exploration of the East Coast.

Okay, Dr. Bill... you've established the background. Now pull it together before this column becomes a novel! The doctoral candidate from New Zealand had read one of my scientific publications in which I mentioned finding a type of nudibranch (Fiona) on the kelp rafts drifting off Catalina. She hoped I still had the preserved specimen to conduct DNA studies. However, I rarely preserved anything in those days, preferring to let my specimens survive and eventually be put back into our waters alive. Given the primitive salt water system I had in my lab, that didn't always happen.

The variable star I showed Sue happened to be another "drifter" occasionally found on my kelp rafts. The interesting thing about that starfish is that it reproduces asexually. A single arm can grow an entire new starfish, as was happening with the one I pointed out. The original arm was quite long and the new arms budding off the central disc were very short. A few decades ago, when I presented my findings at a scientific conference, Dr. Florence McAlary (formerly the wife of the director of the USC Lab) had an "Aha" moment. She had been studying the variable or comet starfish and wondered how they might have gotten to the island. By the way, back in 1997 Flo published a book titled You Can Be a Woman Marine Biologist. Of course I have not read it since the only route for me to achieve that is somewhere I ain't going! However, young women who are interested in a career in the field may want to.

A number of other interesting finds were revealed in that early scientific research. In addition to the variable starfish, dozens of species that only reproduce asexually were found on drifting kelp rafts. I even had an inquiry from the Middle East asking how a form of solitary coral could have drifted on one since they don't attach to kelp. I answered that the coral was attached to a rock that the kelp holdfast adhered to and it broke off with the drifting kelp. We also found a form of sea anemone that broods its young in pits located at the parent's base. Since the young do not disperse until they crawl away from the parent, and they don't travel far, kelp rafting offered an explanation for how they got to Catalina.

Why was this research important? The majority of marine critters reproduce sexually. Many of them, including fish, cast their sperm and eggs into the water where they fertilize externally (what fun is that?). The fertile eggs then drift in the water column with the currents. They may hatch into larvae that continue this journey until they grow big enough and "decide" to settle down. We all know the young of our own species often drift for a while before doing so. Species using this common option often have little problem dispersing to an offshore island like Catalina (although a long distance trip to places like Hawaii is much less likely). However those that do not need a mechanism to transport them to new locations and kelp rafting is an excellent one!

© 2011 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Detached and drifting kelp holdfast, underside of holdfast showing critters rafting on it;
variable sea star growing new arms and solitary cup coral on rock.

This document maintained by Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia