Aquatic Plastic Debris

How plastics get into lakes, rivers, and oceans

Pollution by plastics has been observed in lakes, rivers, and oceans throughout the world (Derraik 2002; Eriksen et al. 2013) Plastics serve an important purpose for lightweight, inexpensive, durable packaging, but these properties and their prevalent usage also make it easy for plastics to enter the environment. Production of plastics has increased markedly over the past 60 years (Thompson et al. 2009), thereby increasing plastic waste.

Plastics end up in water bodies mainly due to improper disposal and littering by humans. A 2010 study found that 4.8-12.7 million metric tons of plastic waste from coastal countries ends up in the oceans each year. There is another source of plastics that may not be so obvious. Plastics can also get into the environment through wastewater treatment plants. Plastic beads in our personal care products (microbeads) and small fibers from our synthetic clothing end up in wastewater from washing ourselves and our clothing. Many of these plastic beads and fibers are too small to be caught by filtration systems in wastewater treatment plants. They are now being found in many different aquatic environments (Mason et al. 2016).

The world has started to take notice of this vast problem. A number of countries (for example, the Sri Lankan government) have banned single-use plastic items and are working to improve waste management. Countries such as the U.S and the United Kingdom (UK) have banned production and sale of products with plastic microbeads. Also, many non-government organizations such as the Ocean Conservancy, the 5 Gyres Institute, and the Alliance for the Great Lakes, to name a few, are working on research, education, and regulations to prevent plastic pollution and help to clean up the oceans, lakes, and other water bodies.

Microplastics and how they form

Microplastics are small plastic fragments, beads, or fibers that are less than five millimeters. Many materials in the environment are slowly decomposed by a variety of bacteria and other organisms. However, most plastics do not breakdown in this way. Plastics break down by either physical or chemical processes or by ultraviolet light. These processes break large macroplastics (>5mm) down to smaller and smaller pieces to form microplastics, but never transform or completely destroy the plastics. In addition, humans have engineered microplastics in the form of microbeads for use in personal care products (banned now in the U.S. and UK), as microfibers from synthetic textiles, and for use in nanotechnologies (some are 5 million times smaller than the largest microplastic).

How plastics affect the aquatic ecosystem

Some of the most obvious impact of plastics on animals occur when animals become tangled up in plastic netting or rings and suffer physical impairments that may lead to death. Animals can also mistake plastics for food. For example, thin film plastics and plastic bags look a lot like jellyfish or free-floating kelp. Small microplastics can look like plankton, which many fish and smaller aquatic life feed on.

Plastics are hard for digestive systems to pass and usually end up sitting in the gut. This gives the animal a false sense of fullness and can lead to starvation and death. In addition, small bits of plastic can have sharp edges that cause significant internal damage. Furthermore, the small bits of plastic could harbor persistent organic pollutants (POPs) that are resistant to environmental degradation or foreign microbes, viruses, and fungi. POPs can negatively affect development, nervous, and reproductive systems. They can bioaccumulate in animals and other aquatic organisms and may move up the food chain (Roland 2000; Rochman et al. 2015). Other foreign substances on or in the plastics can weaken immune systems and cause animals to be more susceptible to disease (Rochman et al. 2013).