The Saddest Sea Creatures in the World Feast on Floating Trash

In the Great Pacific Garbage Patch, a new paper reports, barnacles end up eating tiny pieces of our discarded plastic.

Barnacles that have not, to our knowledge, feasted on plastic trash (Shutterstock/Tetyana Moshchenko)

In the middle of the Pacific Ocean, halfway between North America and Asia, there is a stretch of sea—roughly the size of Texas—that is officially known as the North Pacific Subtropical Gyre. More commonly, it is known as the Great Pacific Garbage Patch. It is essentially a swirl of trash, the drifting detritus of human existence, that ocean currents have accumulated into one massive, trashy expanse. The gyre is home not only to floating junk, but also to sea creatures that are adapting—because they can and because they must—to its membrane of human refuse.

Back in 2009, the marine biologist Miriam Goldstein traveled to the gyre to study the species making a go of it in among the maritime muck. In the process, Goldstein collected samples of those species, among them gooseneck barnacles—creatures that are, Goldstein explains, "essentially a little shrimp living upside down in a shell and eating with their feet." The organisms, unlike some other barnacle species, have a stalk that is long and muscular.

Goldstein preserved the barnacles she collected, and kept them preserved (yep, from gyre to jar) for several years. She asked a colleague working in the gyre in 2012 to collect more. She recently processed the samples.

I'll let Goldstein, writing about her work in Deep Sea News, take it from here:

Eventually I found myself in the lab dissecting barnacles in order to identify them. As I sat there, I thought “Well, I’m working on these barnacles anyway – wonder what they’re eating?” So I pulled out the intestine of the barnacle I was working on, cut it open, and a bright blue piece of plastic popped out.

Yep. Blue plastic, inside the creature's intestine. "I reached into my jar o’ dead barnacles and dissected a few more," Goldstein continues, "and found plastic in their guts as well."

Goldstein and a colleague, Deborah Goodwin, ultimately dissected 385 barnacles. And about a third of them (33.5 percent) had tiny pieces of plastic in their guts. Most of those organisms had eaten "just a few particles," Goldstein notes, "but we found a few that were absolutely filled with plastic, to a maximum of 30 particles, which is a lot of plastic in an animal that is just a couple inches long." 

They analyzed the plastic, as well, and determined that it was generally representative of the microscopic plastic that floats on the ocean surface within the gyre. (It was a combination, the pair note in the paper they published about the finding, of polyethylene, polypropylene, and, less commonly, polystyrene.) Which would suggest, Goldstein notes, that "the barnacles are probably just grabbing whatever they come across and shoving it into their mouths." 

(A) A dense aggregation of Lepas spp. barnacles growing on a buoy and attached line, collected in October 2012. (B) Basic anatomy of Lepas denoting the capitulum, which includes the body and its enclosing plates, and the peduncle, the muscular stalk that attaches the barnacle to the substrate. (C) Microplastic ingested by an individual barnacle. (PeerJ)

So this is where our trash—our soda bottles, our coffee cups, our kids-meal toys—can end up when it breaks down: inside the intestines of hungry, and unsuspecting, sea creatures. In some sense, Goldstein notes, it's entirely logical that gooseneck barnacles would be eating plastic. "They are really hardy, able to live on nearly any floating surface from buoys to turtles, so they’re very common in the high-plastic areas of the gyre." Plus, "they live right at the surface, where tiny pieces of buoyant plastic float." Not to mention the fact that "they’re extremely non-picky eaters that will shove anything they can grab into their mouth."

Goldstein notes that the amount of plastic found in her samples is likely not fully representative of the amount of plastic the barnacles actually consume. They probably eat much more plastic than their preserved digestive tracks indicate. ("Barnacles are perfectly capable of pooping out plastic—I observed plastic packaged up in fecal pellets, ready to be excreted the next time the barnacle had access to a couple minutes and a magazine—so it is very likely that more barnacles are eating plastic than we were able to measure.") And one piece of good news, Goldstein and Goodwin note in their paper, is that the plastic particles didn't seem to block the barnacles' stomachs or intestines.

That leads to another concern, though. Since barnacles are small, and since goosenecks are eaten by larger predators like sea slugs and crabs, does that mean that the creatures are introducing plastic into the food chain? Are there traces of trash in our Chicken of the Sea?

Not to worry, Goldstein says. "Fish don’t seem that interested in barnacles," she notes, "maybe because those fish didn’t evolve with a ton of floating debris." While, yes, it's possible that the barnacles' ingestion of plastic particles could transfer plastic or pollutants through the food web, "it is far from clear this is the case." Then again, a 2006 study estimated that at least 267 marine species had ingested trash—and these included mammals, birds, turtles, and fish. So the barnacles aren't alone in their decidedly unfancy feast.

Via Ed Yong