Plastic Debris Effects on Marine Species and Ocean Life

Introduction to Marine Plastic Debris

Marine litter has been a significant threat to marine life, with plastic debris being the most pervasive component. Marine debris is defined as any solid material that finds its way into bodies of water. This debris has many negative effects on aquatic life, and close to 80% of all marine debris is plastic in nature (Van et al.; Weisman).

According to the Greenpeace Report on Plastic Debris in the World's Oceans, over 260 different species of marine life are known and documented to have been adversely affected by being trapped in marine litter or by ingesting it (Allsopp et al. 2). These species include whales, seals, seabirds, sea lions, turtles, and fish. Concerted efforts must be developed and implemented to alleviate the dangerous effects of plastic debris in order to preserve and protect marine life.

In research conducted on the percentage of plastic in marine debris worldwide, the following regional figures were recorded: approximately 92% of sea-bed marine debris in the North Eastern Atlantic consisted of plastics; approximately 70% of sea-floor marine debris along European coasts was plastic; South Australia recorded approximately 62% plastics in beach marine debris; South Africa recorded 88%; and New Zealand recorded 75% (Derraik 843). These figures were aggregated from several studies conducted around the world, and the global trend indicates that between 60% and 80% of marine debris is plastic in nature.

Plastics are artificial compounds, most of which are built from polyesters, and they vary in shape, color, and size depending on their composition and the dyes used. Plastic waste is of major concern because we encounter plastic materials in virtually all daily activities. The most problematic characteristic of plastic materials is that they are not easily decomposable or biodegradable. However, they do break down into smaller particles and simpler compounds. Plastics whose size is less than 5 mm in length are referred to as microplastics (Arthur 2).

This process of breaking down into smaller particles is extremely slow and may take years or even decades. Even when plastics fragment into smaller particles, they cannot be fully mineralized into their individual components such as carbon dioxide, water, and inorganic molecules. Plastics are best disposed of in landfills and compost piles, where heat, moisture, and bacterial activity can assist decomposition. In the ocean, however, conditions are far less favorable, and water impedes the degradation of plastics (Martins and Sobral 1).

Common plastic types found in marine debris include the following: polyethylene terephthalate (PET), used in soda bottles; polyethylene (PE), used in supermarket bags and plastic bottles; polyester (PES), used in textiles; polyvinyl chloride (PVC), used in plumbing pipes; polyvinylidene chloride (PVDC), used in food packaging; polystyrene (PS), used in food containers and cutlery; high-impact polystyrene (HIPS), used in vending machine cups; polypropylene (PP), used in yogurt cups, drinking straws, and bottle caps; polycarbonate (PC), used in compact discs and eyeglasses; polyamides (PA), used in toothbrush bristles and fishing lines; polyurethanes (PU), used in thermal insulation; high-density polyethylene (HDPE), used in milk bottles and detergent containers; and low-density polyethylene (LDPE), used in floor tiles and outdoor furniture.

These plastic materials are found in everyday items commonly used by people at the beach. In a study conducted in the Western North Atlantic Ocean on the size, mass, and composition of plastic debris, the most commonly identified plastic types were low- and high-density polyethylene (LDPE and HDPE), polypropylene (PP), polyethylene terephthalate (PET), nylon 6 (PA6), polystyrene (PS), and polyvinyl chloride (PVC) (Moret-Ferguson et al. 1874).

Plastic materials have also been widely adopted in the manufacture of fishing equipment due to their relatively low cost. Previously, natural fibers and metals were used to make fish nets and fishing lines; however, today the majority of these are manufactured using plastics. The problem is further compounded by the enormous number of people who visit beaches around the world every day. Popular beaches can receive thousands of visitors daily, creating serious waste management challenges and contributing significantly to the rise of plastic debris in marine waters.

Sources of Plastic Debris

The activities that serve as sources of plastic debris can be divided into four main categories:

1. Tourism-related litter — this is litter left by tourists visiting the beach. It includes food packaging materials, food containers, plastic toys, beverage containers, cigarette matter, and similar items.

2. Sewage-related waste — this type of waste enters the sea through storm drains and combined sewer systems that carry both runoff water and sewage. When these systems discharge into oceans, rivers, or lakes, they introduce plastic debris into marine waters. Examples include food packaging materials, used condoms, plastic toys, and beverage containers.

3. Fishing-related waste — this waste is introduced through fishing activities, including when fishing nets or pieces of nets and fishing lines are accidentally left in the water or break away and drift into open waters.

4. Waste from boats and ships — this category covers all waste generated by people aboard ships, as well as structural pieces that break off and enter the water. Such waste may be accidentally or intentionally dumped into the sea.

An alternative classification divides sources of marine plastic debris into two broad categories: land-based sources and sea-based sources. Land-based sources are those from which debris is washed, blown, or discharged into the sea from land. The UN GESAMP (United Nations Joint Group of Experts on the Scientific Aspects of Marine Pollution) estimates that approximately 80% of marine debris originates from land-based sources. These sources arise from five principal activities. First, stormwater collects during heavy rains and can sweep street litter into drainage systems that discharge into rivers, lakes, and oceans. Second, combined sewers carry both stormwater and sewage; during heavy rainfall events, their capacity can exceed what sewage treatment plants can handle, and excess flow may be discharged directly into waterways carrying plastic waste. The remaining land-based activities include littering, industrial activities that introduce plastics into marine waters, and the disposal of solid waste at sea — a practice known as sea barging, which was once widely used.

The second category, sea-based sources, encompasses four major activities through which plastic debris is introduced into the ocean either accidentally or deliberately. These activities include commercial fishing, recreational boating, and operations involving oil tankers, military vessels, and merchant ships. Offshore oil and gas platforms also contribute to the introduction of plastic debris into ocean waters.

Plastic debris has also occasionally been attributed to alien spacecraft crashing into the sea. While this suggestion can be readily dismissed given that the existence of extraterrestrial visitors remains unsubstantiated, it has appeared in some discussions of unusual debris.

Size and Amount of Plastic Debris

There are three principal types of marine plastic debris:

1. Floating debris — this is debris that is less dense than water and therefore floats on the surface. Studies have found that the amount of floating debris in most areas ranges between 0 and 10 items per square kilometer. In the English Channel, however, higher densities have been recorded in the range of 10 to 100 or more items per square kilometer. Indonesia recorded the highest concentrations, with more than 4 items per square meter. This floating debris is thought to be contributed primarily by waste from boats, ships, and fishing expeditions.

2. Seafloor debris — this is debris that is denser than water and sinks to the bottom. Studies conducted in waters around the world found that European waters had the second-highest quantity of seafloor debris, averaging approximately 101,000 items per square kilometer. Indonesia again recorded the highest values, with nearly 700,000 items per square kilometer.

3. Shoreline debris — this is debris found at the water's edge. Indonesia ranked second in this category at approximately 29 items per meter of shoreline, while Sicily in Italy recorded the highest values at approximately 231 items per meter. In Indonesia, shoreline litter covers approximately 90% of the upper shore.

Conclusion

Marine debris is known to have many dangerous effects on marine animals, and plastic debris in particular poses the greatest threat. Some effects are direct and others indirect. Direct effects result from the ingestion of debris or the entanglement of animals in it. Indirect effects include the use of plastic materials as nesting material by seabirds and the attraction or generation of dangerous pollutants. This plastic debris originates from a variety of land-based and sea-based sources.

Various international regulations have been developed to address the problem of plastic debris. However, regulations alone are insufficient for effective management. Complementary approaches — including public education, adoption of zero waste strategies, active cleanup operations, waste buyback programs, and the development of advanced deep-water survey, retrieval, and removal equipment — must be pursued alongside regulatory frameworks to achieve meaningful and lasting reduction of plastic debris in the world's oceans.

Works Cited

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Arthur, Courtney. Plastic Marine Debris: An In-Depth Look. 2010. Print.

Dong-Oh, Cho. "The Incentive Program for Fishermen to Collect Marine Debris in Korea." Marine Pollution Bulletin 58.3 (2009): 415–17. Print.

Derraik, Jose G. B. "The Pollution of the Marine Environment by Plastic Debris: A Review." Marine Pollution Bulletin 44.9 (2002): 842–52. Print.

Jung, Rho-Taek, et al. "Practical Engineering Approaches and Infrastructure to Address the Problem of Marine Debris in Korea." Marine Pollution Bulletin 60.9 (2010): 1523–32. Print.

Martins, J., and P. Sobral. "Plastic Marine Debris on the Portuguese Coastline: A Matter of Size?" Marine Pollution Bulletin. Print.

Moret-Ferguson, Skye, et al. "The Size, Mass, and Composition of Plastic Debris in the Western North Atlantic Ocean." Marine Pollution Bulletin 60.10 (2010): 1873–78. Print.

Raum-Suryan, Kimberly L., Lauri A. Jemison, and Kenneth W. Pitcher. "Entanglement of Steller Sea Lions (Eumetopias jubatus) in Marine Debris: Identifying Causes and Finding Solutions." Marine Pollution Bulletin 58.10 (2009): 1487–95. Print.

The Department of the Environment, Water, Heritage and the Arts. Impacts of Plastic Debris on Australian Marine Wildlife. 2009. Print.

Van, Almira, et al. "Persistent Organic Pollutants in Plastic Marine Debris Found on Beaches in San Diego, California." Chemosphere. Print.

Votier, Stephen C., et al. "The Use of Plastic Debris as Nesting Material by a Colonial Seabird and Associated Entanglement Mortality." Marine Pollution Bulletin 62.1 (2011): 168–72. Print.

Weisman, A. The World without Us. New York, NY: Thomas Dunne Books/St. Martin's Press, 2007. Print.