You might have heard a few supposed facts about plastic in the ocean: 1) There is a massive swirling gyre of plastic, the “Great Pacific Garbage Patch,” between California and Japan that is twice the size of Texas; and 2) this plastic debris outweighs plankton and is growing in size. Interestingly, the scientific literature does not support these statements.
In 2008, I participated in one of the few scientific expeditions aimed at characterizing the abundance of plastic debris and the associated impacts of plastic on microbial communities. That expedition was part of research funded by the National Science Foundation through C-MORE, the Center for Microbial Oceanography: Research and Education.
Standing on the bow of a research ship, floating in the heart of the alleged garbage patch, my colleagues and I looked out onto a calm, apparently pristine blue ocean. By towing a mesh net through these waters and deploying instruments capable of measuring particle size and abundance, it became clear that the sea around us actually contained few, very small pieces of plastic. If you were to line up 1,000 1-liter Nalgene™ bottles filled with ocean water from this location, one to five of them would contain a single piece of plastic roughly the size of a worn-down pencil eraser. In comparison, plankton (millions to billions of organisms per milliliter) outnumber and outweigh plastic by a considerable measure.
The amount of plastic out there isn’t inconsequential, but using the highest concentrations ever reported by scientists, the plastic debris floating in the surface waters of the North Pacific could be rounded up to produce a patch that is a small fraction of the state of Texas, not twice the size. This is not to say that the issue of plastic in the ocean should be dismissed; rather, the problem is more complex and enigmatic.
One of the longest records of ocean plastic comes from the western North Atlantic. Compiling a 22-year survey of plastic debris, researchers reported concentrations very similar to what we found in the Pacific, but there was a catch. The amount of plastic in the North Atlantic has not increased since the mid-1980s, despite a surge in plastic production over the same period. This unexpected conclusion has led to a lot of speculation: Are we doing a better job of preventing plastics from getting into the ocean? Is more plastic sinking out of the surface waters? Is plastic being more efficiently broken down? At present, we just don’t know.
New research findings may point to one part of the answer: microbes! Not only is plastic prime real estate for microbes, but they may actively degrade it. This interesting finding may partially explain the mystery of “missing plastic” in the Atlantic.
If there is a take-home message, it’s that plastic clearly does not belong in the ocean. The practical solution is to reduce the input of plastic into our oceans in the first place. There is no need to exaggerate the problem to Texas-sized proportions.