The Presence of Microplastics in Hydrozoa and Ctenophora in Friday Harbor, WA

Abstract

Plastics are an essential material for everyday life due to their durability and versatility but can break down into smaller pieces termed microplastics (<5mm). These fragments end up throughout the water column of the ocean and are consequently ingested by a variety of species leading to physical harm to the organism and introduction into the marine food web. Microplastics that float on the surface often cohabit with jellies, specifically hydrozoans and ctenophores. This study aims to observe whether hydrozoans, Clytia gregaria, and ctenophores, Pleurobrachia bachei, ingest microplastics which may indicate another pathway into the food web. Three experiments were conducted to test if the jellies would 1) ingest microplastic present exclusively, 2) ingest copepods, their natural food source, in a laboratory setting, and 3) ingest microplastics even in the presence of copepods. The results of the experiments showed that the jellies did ingest microplastics when presented to them. When there was a presence of microplastics and copepods, both species still ingested microplastics. Overall, this study demonstrates that Clytia gregaria and Pleurobrachia bachei will ingest microplastics, even in the presence of their natural prey. This thus illustrates these two species of jellies are a potential route for microplastics to enter the food web.