Plastic Debris
Plastic is something we use mindlessly everyday for cooking, storage, travel, amongst many others. As a material it is lightweight, durable, strong, and cheap to manufacture. It’s no wonder our world is so blind for the horrors that plastic causes outside of our small bubble of a world. The same reasons we love using plastics in a variety of manufacturing also turn out to be an increasing hazard to the natural environment. Their durability and buoyancy allow these materials to be deposited hundreds of miles away, where they may persist for centuries (Derraik, 2002). Pollution can consist of chemicals including persistent organic pollutants (POPs) and trace elements (heavy metals), both of which are highly resistant to decay. These materials can bioaccumulate in marine organisms and biomagnify through the food chain (Townsend, 2017). Marine debris is a major problem that has been consistently worsening for decades. Marine debris is defined as any man-made product that enters the marine environment; plastic polymers make up 60-80% of these materials (Townsend, 2017).
Plastic materials easily reach marine environments when not disposed of properly. The majority of marine debris originates from land based sources, while 20% are discarded or lost at sea from vessels (Townsend, 2017). Merchant ships and fishing fleet’s dump hundreds of thousands of tons of fishing gear, synthetic packaging material, and plastic containers each day. Recreational fishing and boats are responsible for dumping large amounts of marine debris, approximately 52% of all garbage in United States waters (Derraik, 2002). Closer to home, these materials also end up in marine environments when lost, carelessly handled, or left on beaches (Derraik, 2002). These materials do not biodegrade, but instead break apart into microplastics that may either be ingested by marine life, or result in entanglement in packaging, synthetic ropes and lines, and drift nets. Many marine mammals, turtles and birds are found to have plastic parties in their stomachs. Marine debris is shown to affect at least 86% of sea turtle species, 44% of seabird species, and 43% of marine mammal species. These numbers are an underestimation, as many victims are likely to sink or be eaten by predators as their survival ability and fitness is lessened (Derraik, 2002). These species may select specific plastic shapes and colors, mistaking them for prey. Seabirds with large plastic loads ingested demonstrate reduced food consumption, thus reducing fitness. The ingestion of plastic debris by small fish and seabirds can reduce food uptake, cause internal injuries and block the intestinal tract (Derraik, 2002). Entanglement in plastic debris, especially fishing gear, threatens endangered sea turtles and fur seals, amongst others. The plastic loops may slip onto their necks, and as the animal grows, the plastic will sever arteries or strangle the animal. Once entangled, the ability of the animal to catch food or avoid predators may be impaired, and the threat of drowning will increase (Derraik, 2002).
Microplastic contamination has consistently increased since the 1970s, affecting many fish and seafood species. In addition to harming the health of these species, these contaminants may find their way back into the diets of humans through seafood consumption and drinking water. Studies investigating microplastic concentrations in drinking water demonstrated that 80% of all microparticles were smaller than 20 micrometers, suggesting that most studies do not find or detect particles this small (Schymanski et al., 2018). Due to the small size of these and microplastics, detecting the adverse biological effects and removal from the environment becomes more difficult (Shim & Thompson, 2018). Engineered microplastics used in cosmetics and sandblasting are introduced by discharge after use or in accidental spills. Microplastics may also be generated in the environment as larger plastic materials fragment. The global plastic production has dramatically increased, reaching 299 million tons in 2014 and still rising. While difficult to measure, an estimate for the amount of floating plastic litter (>0.33 mm) is 0.27 tons, with micro plastics accounting for 92% of the plastic particles and 13% by weight. The numbers are much higher when also accounting for litter on the seabed and beaches. These microplastics are ingested by invertebrates, turtles, fish, birds and marine mammals, and biomagnify up the food chain threatening the entire ecosystem (Shim & Thompson, 2018).
Polythene bags commonly used at grocery stores, dry cleaners, and as household trash bags, often drift into oceans and are attracted by turtles, as they resemble jellyfish and other food sources (Derraik, 2002). Balloons are another look-alike for jellyfish, and threaten sea turtles, seabirds, and marine mammals (Townsend, 2017). Whales, manatees, and dolphins are also threatened by the plastic and marine debris. Upon their death, studies and autopsies may be performed to identify the cause of death, often finding polytene bags, fishing line, and waste from human food packaging such as chip bags, water bottles, and plastic cups and utensils (Derraik, 2002).
The threat of plastics has only recently begun to be recognized. Over the past few decades, organizations have implemented regulations and efforts to reduce marine debris and the devastation that results. In 1988, the Marine Protection, Research, and Sanctuaries Act was passed. This prohibits 1) transportation of material from the United States for the purpose of ocean dumping, 2) transportation of material from anywhere for the purpose of ocean dumping by U.S. agencies or U.S. flagged vessels, and 3) dumping of material transported from outside the United States into the U.S. territorial sea (epa.gov). In 2006, the Marine Debris Research, Prevention and Reduction Act was passed to establish programs within the National Oceanic and Atmospheric Administration (NOAA) and the US Coast Guard to identify and determine sources of, assess, reduce, and prevent marine debris. On a more local level, many organizations are taking efforts to reduce marine debris and human impact on marine environments. The Cape May Whale Watch and Research Center takes part in a program known as The Clean Ocean Initiative, where marine debris including balloons or floating plastic is removed during trips on the vessels. Beach cleanups occur worldwide, in which small or large groups roam beaches collecting garbage and other debris left on the beaches to prevent them from entering the ocean. When done with an organization, the collections are often sorted to characterize the collected debris. In 2016, I was fortunate enough to travel to Australia and work on marine conservation and sustainability there. We studied the effects of marine debris, and completed beach cleanups in Port Douglas in Queensland, Australia. After thirty of us collected debris, we sorted through the garbage to compile data on what we found. This information is useful in determining the major threats and causes of debris on different beaches around the world.
Beach cleanup in Port Douglas in Queensland, Australia. Photo by Kayla Varnon
-Kayla Varnon, Virginia Tech
Intern at Cape May Whale Watch and Research Center
Derraik, J. G. B. (2002). The pollution of the marine environment by plastic debris: a review. Marine Pollution Bulletin, 44(9), 842-852. doi:https://doi.org/10.1016/
Schymanski, D., Goldbeck, C., Humpf, H.-U., & Fürst, P. (2018). Analysis of microplastics in water by micro-Raman spectroscopy: Release of plastic particles from different packaging into mineral water. Water Research, 129, 154-162. doi:https://doi.org/10.1016/j.
Shim, W., & Thomposon, R. (2015, 10//). Microplastics in the Ocean, Editorial. Archives of Environmental Contamination & Toxicology, pp. 265-268. Retrieved from http://login.ezproxy.lib.vt.
Townsend, K. (2017). HUMAN IMPACTS ON THE MARINE ENVIRONMENT OF QUEENSLAND. Geodate, 30(4), 3.v