By Christina Albright-Mundy
Barnacles are crustaceans, related to lobsters and shrimp. Barnacle larvae spend their youth swimming in the open ocean amongst the zooplankton, but spend their adult lives anchored head first on rocks in the upper regions of the intertidal zone.
Using a strong, self-made adhesive, barnacles anchor in place and begin forming the calcite plates that will form their trademark stratovolcanic shape. At the top of the cone, four plates form a door that the barnacle is able to close to form a leak-proof seal during low tide. At high tide, the barnacles will open the door and stick out legs outfitted both with tiny hairs for filter feeding on phytoplankton and with gills for gas exchange.
With plastic debris littering our oceans to an ever-greater extent, it should come as no surprise that barnacles have also been impacted. A recent study of the North Pacific gyre revealed that almost 34 percent of the barnacles living in this region contained some plastic in their digestive systems. The study, which involved the collection and necropsy of 385 barnacles, was meant to identify the presence of micro-plastic, material measuring less than 5 mm in diameter, inside the digestive systems of these animals.
Barnacles that were collected were attached to floating debris, and almost 34 percent of them contained some micro-plastics in their digestive systems. Of those barnacles containing micro-plastics, nearly half of them contained more than three pieces; one barnacle contained 30 pieces of micro-plastic. It is of note that the plastic removed from the barnacles was a multitude of colors, not just the color of the debris they were attached to, which indicated that the barnacle was not obtaining the micro-plastic through their host debris, but from a variety of sources.
While it is not believed that the ingestion of micro-plastics is an immediate danger to the barnacles, there is the risk that through increased micro-plastic ingestion, and the subsequent decrease in phytoplankton intake, that these animals could suffer malnutrition.
A more pressing issue is what this study tells us about the occurrence of micro-plastic and plastic ingestion by all marine animals. This is a direct demonstration of the polluted state of our oceans and how it affects the ocean ecosystem. There are 267 marine species that have been identified as consuming plastic materials, and for some it proves fatal.
Current estimates have placed the size of the North Pacific gyre at twice the size of the state of Texas. There are 11 million tons of floating plastic in this 5-million-square-mile area, which is corralled by currents and the wind.
And though we may never be able to clean the ocean of plastic, we can help prevent the addition of further debris by using reusable shopping bags and water bottles, by encouraging stores to discontinue use of plastic bags and by recycling and collecting trash, especially from around waterways. Though it may seem a small step, each of us can make a difference in the amount of trash added to the North Pacific gyre and help keep micro-plastic away from barnacles — and everything else in the sea.
