Air Date: Week of December 16, 2011
The team at Southern Maine Community College assembles drifters that either float at the surface or hang about 5-10 meters beneath it, and then get pushed along by the currents. (Photo: Tom Long.)
Little floats armed with GPS units are providing scientists and fishermen with important information about ocean currents. These so-called drifters can monitor movement of fish, and the path of oil spills and waste. Producer Ari Daniel Shapiro went out with a group of students and scientists to drop some drifters into the water.
GELLERMAN: It's Living on Earth, I'm Bruce Gellerman. To measure and calculate the flow of ocean currents, scientists use a simple device called a drifter. It's a little float carrying a satellite tracking unit. But as Ari Daniel Shapiro reports, drifters play a big role for lobstermen who use them and for the students who build them.
MANNING: Each drifter has a story to it.
SHAPIRO: The story of the drifter project starts with this guy, Jim Manning. He’s an oceanographer with the National Oceanic and Atmospheric Administration in Woods Hole, Massachusetts. And Manning’s the one who thought up the idea of partnering with a variety of community colleges to design and build drifters. Drifters that could be used by the colleges for their own research, and to facilitate the science of oceanographers elsewhere. Manning leads me outside.
[SOUND OF DOOR OPENING]
MANNING: We’re just going out to the storage barn here where I keep all my junk and assorted parts of drifters.
[SOUND OF JANGLING KEYS]
SHAPIRO: He shoves open the door to reveal a large warehouse filled with metal shelves piled up with all sorts of salt-encrusted equipment.
MANNING: I should clean this out someday.
SHAPIRO: We walk down one of the aisles and dust off some gear.
MANNING: Let’s see if we have any parts. These are some of the older units.
[SOUNDS OF RUMMAGING THROUGH STUFF]
MANNING: Simple flotation with stainless hardware, fiberglass rods that hold the sails together.
SHAPIRO: There are a handful of different drifter models here. The ones being built these days are made from PVC piping, cantaloupe-sized Styrofoam floats, and flexible plastic sheets or sails. The sails wrap around the PVC skeleton kind of like a hoopskirt and give the currents something to push against. The flotation is rigged to get the drifter to hang at a particular depth: at the surface, say, or five meters underwater.
A few weeks later, on a cold, bright morning, I'm standing near the dock at Southern Maine Community College, or SMCC. A team’s getting ready to take a boat out a short ways to drop a couple of drifters into the water. Brian Tarbox is part of that team. He’s a faculty member at SMCC and a former lobsterman. Tarbox unfurls a map showing me where we’re headed.
[SOUND OF MAP UNFURLING]
TARBOX: So, here we are right here on the South Portland shore. What we’re looking for is to get the drifters out past Cape Elizabeth. We start ’em off in Hussey Sound. Hussey Sound’s got a pretty good current on the going tide. They’ll have to run through the gauntlet of lobster gear.
SHAPIRO: How do you steer around that, do you just hope, kind of?
LONG: Yeah, that’s pretty much it.
SHAPIRO: Drifters move passively with the currents. They can’t be guided once they’re set afloat. So the drifters might snag or get entangled on the lobster gear scattered all over the sound. But as long as they steer clear of all that, then they’ll provide tracks of where the currents are flowing and where the water’s moving.
Each drifter’s got a small GPS transmitter glued to it that relays its position via satellite for remote tracking. Tom Long is the science lab manager at SMCC.
LONG: Students who’ve come onto the project are asked to help design and build these units that are gonna be used by researchers, not just by us. What the students get out of that from a practical point of view is how to think about design, how to put that design into action, into reality. And then there’s just the physical skills of learning how to build things, you know, use a table saw, that kind of thing.
SHAPIRO: And are you nervous about anything, or is there anything to be concerned about today?
LONG: Today? Nah, the only thing I’m nervous about today is the transmitters, to be honest with you. They’ve been a little quirky for us lately. And so I’m going to be very anxious within the next hour or two to see that we’re actually getting good fixes. That’s what I’m nervous about. But other than that, have a good trip!
[BOAT SOUNDS: All set? All set.]
SHAPIRO: As we motor out towards Hussey Sound, Catherine Chipman, one of the students involved with the project, points out a couple of landmarks.
CHIPMAN: That’s Fort Gorgeous right over there. Think that’s Peak’s Island.
SHAPIRO: So, can you tell me, you’ve been involved with helping to build some of the drifters as well?
CHIPMAN: I did for a short period of time, but then my school schedule didn’t really allow me to work on them too much.
SHAPIRO: These days, Chipman’s working on a research project using the data from some of the drifters she used to build. The drifters we’re deploying today are going be used by a professors at SMCC to teach about local currents in his oceanography class.
[SOUND OF CHANGING BOAT’S GEARS]
SHAPIRO: Tarbox steers the boat to the deployment location. One of the drifters is to float at the surface, and the other is to drift about 5 meters down.
LA LOMIA: We ready?
TARBOX: I guess so, yeah.
LA LOMIA: I think I’ll put this in first.
SHAPIRO: The drifters are on their way pretty quickly, and Kara La Lomia, a technician who helped to build them, looked delighted.
LA LOMIA: (Laughs.) That’s trucking along pretty good, isn’t it?
SHAPIRO: So what are you thinkin’? Does it look good?
LA LOMIA: It looks very good. And it’s nice to be able to see the two side by side and compare how they’re floating for right now. We’ll have to see what happens here.
SHAPIRO: We watch the drifters move off for a couple of minutes. Then Tarbox guides us expertly back to the dock. I turn back to La Lomia. So what’s it like to kind of come out here and say goodbye to them? To kind of put them in the water, and set them free?
LA LOMIA: It’s always very exciting. I like to be part of coming out here to let them go. I’ve worked on them for so long, and it’s just great to see them go out.
SHAPIRO: When we get back to the dock, a tall, trim, local lobsterman named Elliott Thomas is waiting for us. We walk inside, and he explains what all this has to do with his line of work.
THOMAS: There seems to be a trend over the last 10 years of getting fishermen involved in science.
SHAPIRO: Do the lobsterman pretty much know why these drifters are out there?
THOMAS: Those who follow do know. I mean, the movement of the drifters can indicate movement of lobster larvae before they settle. So it’s a good thing for people to know.
SHAPIRO: By tracking ocean currents, the drifters can also say something about how fish and clam larvae get dispersed. Where invasive crabs might end up, or the path that waste might take coming from a power plant. These drifters even helped keep track of the oil spill on the Gulf of Mexico. Before leaving campus, I drop by Thomas Long’s office to make sure the transmitters on those two drifters we deployed are working okay.
LONG: As you can see, we’ve got two relatively new pings off of our drifters, which is a good thing.
SHAPIRO: So, this must be kind of, I mean this is exciting for me: We just went out on the boat to put these things in the water, and you’re already getting data right here in your lab.
LONG: Well I get excited every time we do it. And it engages the students too.
CHIPMAN: It’s like you learn one thing and then you keep wanting to know more about it ’cause there’s really no end. It’s like seeing something interesting and then being like, ‘Oh, I wonder what that’s all about.’ And then actually getting to really try and figure it out. I think that’s awesome.
LONG: It’s almost like having pets out there that you can watch, you know? People get very interested in it, in following it, in where they’re going.
SHAPIRO: For Living on Earth, I’m Ari Daniel Shapiro.
GELLERMAN: Our story – Adroitly Adrift – comes to us from Ocean Gazing, a podcast about our seas produced by COSEE NOW. To learn more about Ocean Gazing and its new teaching curriculum, drift over to our website: loe.org.
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