Scientists have discovered that microplastics in the ocean can seriously harm the health of marine worms (sea worms), a species at the bottom of the food chain, through ingestion, further impacting the overall marine ecosystem.
Microplastics can be composed of polyethylene, polyethylene terephthalate, polyvinyl chloride, or polystyrene. Because of their small size, they are difficult to filter out by current wastewater treatment processes and end up in the ocean. Since the 1960s, microplastics smaller than 5 millimeters have been accumulating in the ocean and are now one of the most common solid pollutants on Earth.
Species at the bottom of the food chain are food for other species and play an indispensable role in the food chain. When sediment contains high concentrations of microplastics and these species ingest it, does it harm them? Two UK studies published in the journal Current Biology explore the impact of these microplastics, which are invisible to the naked eye, on species at the bottom of the food chain.
A study by the University of Exeter in the UK, using sea worms, found that sea worms foraging in highly polluted waters consumed less food and had less energy. A study by the University of Plymouth, however, is the first to discover that worms ingesting microplastics also consume pollutants and additives, affecting their health and biodiversity. Many other organisms and worms exhibit similar foraging behaviors, such as starfish, sea cucumbers, and fiddler crabs, and these organisms may also be affected in a similar way.
Microplastics fall into three categories: The first is "nurdles," a type of plastic raw material. When melted, these can be made into larger plastic objects or used to create exfoliating granules in skincare products. The "nurdles" found on the windward side of the Nansoko Islands in Hong Kong are examples of plastic granules used as raw materials. The second type consists of smaller particles resulting from the breakdown of large pieces of plastic over time. The third type is fibers, derived from synthetic fabrics such as polyester. Each wash of synthetic clothing releases up to 1,900 tiny fibers.
Research has found that microplastics can carry many different chemical components that may harm worms. Many plastics contain additives such as plasticizers, dyes, or antimicrobial chemicals, which can be released into seawater and seabed sediments. Water-based chemicals such as pesticides or detergents can also accumulate on the surface of microplastics.
The impact of major marine plastic pollutants on marine life is well-known; there are numerous documented cases of fish and birds becoming entangled and suffocating after ingesting plastic waste. However, many more marine creatures at the bottom of the food chain may be affected by ingesting microplastics.
Sources: Environmental Information Center (2013-12-5)
