Our oceans are polluted with a wide variety of marine debris, ranging from tiny cigarette butts and plastic bags to 4,000-pound derelict fishing nets and abandoned vessels.
The National Oceanic and Atmospheric Administration (NOAA) defines marine debris as any “persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment or the Great Lakes.”
Trash and debris along the coasts of the United States mainly comes from littering or mass dumping. It washes down storm drains, through our waterways and ultimately into the sea. Marine debris can also come from coastal activities ranging from beach-goers leaving behind picnic food packaging to mismanagement of accumulated waste that’s been destined for export or landfill.
According to reporting by the US Environmental Protection Agency (EPA), trash, packaging, and improperly disposed waste from sources on land accounts for 80% of the marine debris found on beaches during cleanups and surveys.
Marine debris is problematic at a local, national, and global level. Because the strength of ocean currents can carry solid pollution into the open ocean, the negative effects of marine debris are not evenly distributed among the living and non-living systems on our planet.
The Plastic Problem
Plastics overwhelmingly dominate the make-up of marine debris. Oceanographic modeling has led researchers to estimate that there are 5.25 trillion plastic particles in the ocean weighing 268,940 tons. That’s 13 times more pieces of plastic than stars in our galaxy!
It’s no surprise this estimate is so massive since marine debris comes from human-created waste, and plastics are used in many aspects of our daily lives. It is estimated that the equivalent of one garbage truck of plastic waste enters the ocean each minute!
More than half of all plastic ever created was produced in the last 15 years, and the scale of production grows every year. By 2050, estimates suggest there will be more plastic in the ocean than fish by weight.
Plastics can enter the ocean in countless different ways, from microfibers released by washing polyester or nylon fabrics in your household washing machine to the microbeads in common personal care products to industrial waste or even forms of eco-terrorism. The one thing plastics have in common is their high durability, at the physical and chemical level. Overtime, plastics will not break down into their components chemically in the same way we’d think of for other natural processes, like a banana peel composting. They will form smaller and smaller plastic pieces, known as microplastics (smaller than 5mm in size). Sometimes they’re already this small from their source, but even the largest forms of plastic marine debris can fragment into these tiny bits that actually make up the vast majority of garbage patches in the deep ocean.
Marine debris, whether plastic or otherwise, significantly interferes with ecosystem and human health, and it has many socioeconomic impacts. The eradication of marine debris is essential to the well-being of current and future generations, and the unique characteristics of marine debris as an environmental problem requires an innovative approach to its eradication.
Some human activities have historically had a positive impact on the environment, but it’s worth acknowledging that many have negatively altered the natural processes and health of ecosystems. Marine debris also bears a disproportionate impact on populations that have been historically marginalized and/or contributed less to the accumulation of marine debris, as well as those who lack the financial resources or political power to address the problem. When taking a step back to look at the bigger picture, however, it is clear that marine debris and plastic pollution also pose tangible threats to coastal assets and economic productivity as we know it.
Through ingestion, entanglement, and interaction; marine debris negatively impact the natural functions of fresh and saltwater ecosystems as well as the activities and health of the organisms that they are home to. From direct damage to habitats or internal organs to external injury or forced migration of non-native species; marine debris plays a role in all levels of the aquatic environment.
Ingestion refers to the common pattern of disillusioned marine life eating marine debris. The jellyfish-like movement of a drifting plastic bag may come to mind, but this problem isn’t limited to physical appearances. A recent study found that sea turtles responded most similarly to the smell of “biofouled” plastics as to that of their own food. This finding suggests that the unavoidable accumulation of microbes, algae, plants and small animals on the surface of marine debris makes it that much more attractive for turtles to eat our trash.
Studies show that ingested marine debris is quite common in samples of dead and captured seabirds and turtles as well as captured fish formerly marked for human consumption. The current literature suggests that many marine organisms mistake small bits of plastic and trash for food, and this has clear effects on the survival of individual organisms, food webs, and health of marine ecosystems at-large.
Many marine organisms have also been found to become entangled in the debris, another interaction that can cause direct physical injuries and death. Entanglement cases have been reported for at least 344 species as of 2015. Derelict fishing gear is particularly harmful as it often results in “ghost fishing.” Ghost fishing occurs when lost or abandoned fishing gear continues to capture and entrap marine life. Debris entanglement can also have damaging effects on marine habitats, such as coral reefs and seagrass beds.
Marine debris also indirectly affects ecological functions. The chemical additives in plastics and other highly processed materials may leach out and impact the chemical composition (and in turn the potential toxicity) of natural water bodies. The physical bulk of debris on the surface can also block the sunlight needed by autotrophic marine organisms at different levels of the photic zone that rely on sunlight to nourish themselves and survive. Once the autotrophs’ productivity declines, we start to see that ripple effect in the fitness and niche of other larger marine organisms up the food web.
Peer-reviewed publications on the impacts of plastic marine debris impacts have been shedding light on the detriment to ecosystems and wildlife as far back as the 1980s. This excellent table showcases such evidence published through 2013 based on analysis by Rochman et al. (2016).
“Researchers are actively examining the physical and chemical effects of ingesting microplastics on organisms and how those chemicals may travel through the food web. Though we know marine debris can impact individual organisms, it is still not clear how it affects populations and communities. This is a data gap that researchers are beginning to explore”. – NOAA
Human Health and Social Impacts
Marine debris is also responsible for a range of short and long-term impacts that reduce public health, safety, and quality of life. This is a complex, far-reaching issue within the problematic reality of marine debris and further research is needed to strengthen the limited data available now.
Whether marine debris is beached on the shorelines or circulating in the oceans, it poses numerous threats to public health. Physical objects (especially netting, shards of glass, and medical waste) can injure people visiting our waterways directly. Meanwhile, chemical additives in plastics and other manufactured products can leach out and pose threats to humans after being exposed to light, heat and/or water. Scientists do not have a clear understanding of the wide range of negative consequences that may result from our exposure to the chemicals leached from marine debris; this is an issue that a great deal of research has been dedicated to more recently. Debris from sewage systems is especially problematic for ecological health because it facilitates the spread of disease through viruses and bacteria.
Studies have shown that plastics absorb contaminants more readily than natural sediments and even some of the other manufactured materials that may comprise marine debris. It’s important to consider the health impacts associated with marine debris and plastics alike, “holistically … rather than one variable at a time.”
The lifecycle of plastics is responsible for a range of serious human health impacts beyond those posed by their eventual discharge into marine environments. Atmospheric emissions and pollution from extraction, transport, manufacturing, consumer use and waste management has historically been disproportionately concentrated in low-income and BIPOC communities.
Dense accumulation of all types of marine debris in coastal communities deters residents and visitors from spending time in their surrounding natural environment. When this repeats over time, it may reduce the physical and mental health of community members by reducing their social contact and exposure to the outdoors.
Marine debris may directly impact the economic well-being of coastal communities by creating a need for cleanup programs that mitigate the public health and safety risks previously discussed.
As we see greater needs for infrastructure to address flood-prone areas, marine debris also exacerbates the severity of flooding episodes by blocking drains and weirs used to divert water. When these systemic defenses fail, there is a high cost for clean up and damage repair that most often hurts the communities in the end by unnecessarily diverting funds from other potentially more effective flood-mitigating public investments.
For coastal communities, shifts in tourism are among the most detrimental and costly impacts that marine debris impose on the local economy. In response to loss of productivity in the tourism industry, local governments and seaside businesses may resort to funneling more money into cleanup efforts in the hopes of regaining the reputation of an aesthetically agreeable environment for recreation.
The difference between a marine or lakeside environment littered with debris and one characterized by “almost none” represented a change in annual recreational value of $19.8 million in Delaware and Maryland, $88 million in Ohio, and $129.7 million in Orange County, California. Changes in recreational activity due to the presence or absence of marine debris impact the regional economy by factoring into the value attributed to local businesses and services in the nearby area. Impacts may range from taxes on production to the level of employee compensation to overall job availability.
Indirect impacts may be just as weighty when environmental degradation over long periods of time reduces property values and “civic pride” amongst residents. It is becoming more difficult for economists and ecologists to set a numerical value for the ecosystem services that are simultaneously declining with the accumulation of marine debris.