Biologists at the Alfred Wegener Institute’s Helmholtz Centre for Polar and Marine Research (AWI) have now investigated just how many of these particles remain in the stomachs of certain fish. It depends quite dramatically on the fish. Some fish have numerous particles in their stomachs. Others have nearly none.
In doing so they discovered that mackerel fish consumed plastics at far higher levels than fish that spend more of their time close to the seafloor. The latter group includes flounder and yellow fin sole. Mackerel had plastics in their stomachs between 13 and 30 percent of the time, depending on the region where they were caught.
In a separate study, Gutow discovered that herbivore invertebrates also ingest plastics while feeding. That study involved Littorina littorea, or the common periwinkle snail, in a laboratory experiment.
Since plastics adhere well to seaweed’s sticky leaves – one of the snails’ favorite dishes – researchers used fluorescent plastic particles attached to the leaves to follow the microplastics inside the snails.
These particles didn’t remain inside the animals for long. After digesting the biological components of the meal, the plastics were excreted.