The good news is that fewer discarded plastic bags have been showing up in our coastal cleanups lately; however, plastic litter we cannot see continues to worry us.
As the group that protects the health of our coastal waters, Friends of Casco Bay felt it was our duty to see if microplastics—defined as plastic fragments smaller than 5 millimeters (smaller than 1/16 of an inch)—are present in Casco Bay.
Unfortunately, we found microplastics in every region of the Bay we sampled.
Last summer, over the course of two days, we collected jars of seawater in Portland Harbor, between Chebeague and Cousins Islands, in Merepoint Bay, and ten miles offshore near Halfway Rock. We found 20 microplastic pieces in total; half of the pieces were from Portland Harbor. Of the 20 pieces of microplastics, 19 were less than 1.5 mm long. 14 of 20 pieces were microfibers. Microplastic films and fragments were present as well. No microbeads and no nurdles were found. (If you don’t know what these are, read more about plastics here.)
The highest number of microplastics were in the samples taken closest to shore, in Portland Harbor (10). We found fewer microplastics around Cousins Island (4), Merepoint Bay (3), and Halfway Rock (3). The fact that we found them at every place we sampled was concerning.
“I think the important message is that we found microplastics in every region of the Bay, just by grabbing a couple of liters of water,” Friends of Casco Bay Research Associate Mike Doan observes. “We found microplastics close to shore and we found them ten miles from the mainland.”
Plastic debris that enters the ocean can break into fragments that are nearly invisible to the naked eye. Mussels and oysters may ingest microplastics instead of plankton. Pollutants, such as DDT and PCBs, may adhere to these tiny particles, making them more toxic to marine life. Accumulations of plastic have been shown to move up the food chain to humans.
We will use our microplastics sampling data as we advocate for policies to reduce plastics pollution in our coastal waters. We plan to repeat the sampling in 2019 and compare it to our 2017 findings, as well as to those of other researchers in other areas of the country.
An article on our study appeared in the January 28, 2018 edition of the Maine Sunday Telegram: