One of my best memories from college is the time I spent on a SEA Semester, sailing around the Caribbean and conducting research from on board a magnificent 134-foot brigantine, the SSV Corwith Cramer (even though I was seasick much of the time and sleep deprived all of the time—there are good reasons why I'm happier as a science writer than a scientist). One of the activities involved towing a net next to the ship either half in and half out of the water or just below the surface. Most tows brought up a variety of ocean life—copepods were common—and at least a small amount of plastic.
Over the last 25 years, Sea Education Association students have collected tens of thousands of pieces of plastic, most of it bits less than a centimeter in size. And about four weeks ago, the Corwith Cramer, with a crew of 11 professionals and 22 volunteers (mostly alumni), set out on a special mission to study the accumulation of plastic in the North Atlantic.
As of this morning, the Corwith Cramer has traveled 3.109 nautical miles, first sailing directly east from Bermuda then following a mostly zig-zag path back to the island nation. They've performed 103 net tows and collected 46,288 pieces of plastic, including a (sadly) record-setting tow on June 21 that netted more than 23,000 pieces of plastic. That's equivalent to more than 26 million pieces per square kilometer (50,000 is considered "high").
It's clear that there's a lot of plastic out there, though it doesn't come in the form of huge floating islands—what you might think of when someone speaks of a "garbage patch" in the sea—and is easy to ignore most of the time you're gliding across the ocean swells. But what happens to the plastic and does it do any harm? Those are two questions the SEA expedition will try to answer. Many kinds of sea life consume the tiny bits of plastic, but does that really hurt them? Do they accumulate any chemicals from the plastic? And does the plastic itself eventually sink to the bottom of the ocean, or does it degrade and break into smaller and smaller pieces? Then what?
Chief scientist Giora Proskurowski provides a daily update on the science end. Yesterday he noted that although the expedition's plastic haul is small in terms of weight (only about 3 pounds if you don't count the big pieces, like a 5-gallon bucket), it represents a huge amount of plastic in the ocean:
Thus the values for plastic concentration that we measure with our nets is rapidly scaled up when we start extrapolating to larger areas. The ounce of plastic we collect in a neuston tow can represent several thousand pounds of plastic in the radius of the Cramer's horizon (say around 20 pounds per square mile), and many millions of pounds in this region of the Atlantic.
Whether these itty bitty bits of plastic turn out to be truly toxic or simply disgusting floating trash, tossing millions (billions? trillions?) of pounds of the stuff into our oceans seems, to me at least, a poor way to treat something so beautiful and full of such interesting (and often tasty) things. (And if you're interested in what ocean currents do to our cast-off debris, check out this excerpt from Flotsametrics and the Floating World.)