Microplastics in Our Fish

Bait fish

George Harvey

We have seen a number of articles about microplastics, or microbeads, in Green Energy Times before. Two examples are Larry Plesent’s article, “Microbeads are in the News!” which appeared in December 15, 2015 (bit.ly/GET-microbeads), and “Garbage Patches in our Oceans,” which appeared in August 15, 2015. (bit.ly/GET-ocean-trash)

Recently, a reader brought more information to our attention. It is specific to microplastics pollution in Lake Champlain, and it may help readers can get a better understanding of the problem.

Microbeads, or microplastics, are plastic particles five millimeters or less in size. The smallest of these particles are too small to see easily. They are so small and light that Brownian motion, the physical phenomenon that accounts for muddy water staying muddy over time, prevents many of them from settling out of the water. That means that they will not go away until they degrade.

Many species of small animals identify microplastics as food. The result is that many of the tiniest animals will get full of them, become unable to digest food, and starve. Those that do not starve are eaten by larger animals in the food chain, so microplastics accumulate in larger species, until the largest fish, such as salmon, can have a fair amount of them in their bodies.

A study conducted by students at the State University of New York at Plattsburgh last year looked at the presence of microbeads in at least fourteen species of fish, along with a number of invertebrate species and at three species of waterfowl. Samples were treated chemically and put through sieves to find the amount of plastic in the flesh of the animals. The only species of those they examined that were found to be free of microplastics were terrestrial isopods, such as woodlice. A poster showing the results of their work is at bit.ly/microplastics-poster.

The microplastics bioaccumulate, so larger carnivorous and omnivorous animals are likely to have greater amounts of them than smaller ones. This is true of many of the lake fish people eat. It is also true of waterfowl. And since waterfowl and other animals leave excreta on land, the pollution of plastics is building there, as well.

We may think of plastics as inert, and they nearly are in some ways. The microplastics represent a serious problem of contamination, however, because they absorb a number of kinds of pollutants, which they can give up to any animal, including human beings, who ingest them. As they accumulate in your body, so do the poisons they hold.

Microplastics come from many different sources. Toothpaste is one example that is well known. It is used in toothpaste as a mild abrasive. They are found in cosmetics also. But they are created as larger pieces of plastic break down with exposure to nature, so major sources include clothing and rope. And since we create and distribute millions of tons of them each year, they have become a nuisance.

Clearly, plastics can have serious problems for just about anything that is alive. There have been proposals that ocean gyres full of them could be cleaned up, if we dedicated hundreds of ships to the work. But that will not help with microplastics, which are difficult to remove from the environment and are found almost everywhere. It appears that one important way to deal with microplastics is to eliminate use of non-biodegradable plastics as much as possible.