Garbage guts

Today's post is my attempt to combine something for World Oceans Day with The Crustacean Society meeting.

Plastic is everywhere, including the oceans. While the "great garbage patch" may be an exaggeration (as Miriam Goldstein has repeatedly told us), ships are estimated to dump about 6 and a half million tons of plastics into the ocean annually.

While people have realized the negative effects of plastics on vertebrates for some time, due to some horrendous pictures of animals laden down or entangled with plastics, the effects on invertebrates aren't as clear. Could they mistake plastics for food and ingest them? And if they did... then what?

Murray and Cowie examined the stomachs of 120 lobsters, captured off the coast of Scotland. (Not a task I envy them). Fully 100 had plastic in their stomachs, usually some ball of plastic filaments.

There seems to be a size factor at work here somehow. The larger animals were less likely to have plastic in their stomach. Whether this is a function of pure digestion - the plastic is easier to pass - or behaviour (the animals are better able to discriminate or sort plastic, or avoid it for some other reason) isn't clear yet.

The authors also found that animals that had just molted were unlikely to have plastic in their stomachs. This is probably due to the fact that when the animal sheds its exoskeleton, it also sort of sheds its gut (or part of it, at least). To be honest, I am not sure how they do that.

Reference

Murray F, Cowie PR. 2011. Plastic contamination in the decapod crustacean Nephrops norvegicus (Linnaeus, 1758). Marine Pollution Bulletin: In press. 10.1016/j.marpolbul.2011.03.032

Photo by caruba on Flickr; used under a Creative Commons license.