Modern oceans have been plagued by pollution for years, annually becoming worse and worse despite advertising and large campaigns to reduce pollution and clean up beaches. To many, pollution simply means trash being discarded on the beach and washed out to sea with the tide. However toxic pollution has become more prevalent, and an increasingly serious problem for oceans all over the world. Toxic pollution occurs when synthetic chemicals, human-made chemicals including pesticides, PCBs and dioxins, are liquidated or broken down, or when natural chemicals accumulate to lethal levels in the environment (“Ocean Issue Briefs”). Air emissions from manufacturing, fuel incineration in cars and motors, and from power plants containing numerous chemicals that are expelled into the atmosphere, accumulate and rain down into oceans worldwide (“Ocean Issue Briefs”). Pesticides are dispersed from agriculture by rain running off chemically treated land and flowing into lakes, rivers, and ocean waters. Pollutants can also be found in run-off coming from roads, parking lots, city streets, buildings, cars and houses (“Ocean Issue Briefs”). This kind of pollution causes reductions in ocean life, corruption of ecosystem functions and can even be threatening human health. Because water is such an effective solvent, most toxic pollution generated by humans eventually ends up in the ocean. After this pollution enters a marine environment, many chemicals inhabit the sediment found on the ocean floor, beaches and the sea surface microlayer (“Ocean Issue Briefs”). One major pollution concern is the breakdown of plastics into microplastics, consumed by a huge number of marine life.
Microplastics, less than 5mm in size, are the products of larger plastics being broken down due to UV, mechanical or microbial fragmentation (Wright). As these microplastics are broken down further and further, filter-feeding animals ingest them as the comb the waters for food. Filter feeding animals include bivalves, planktivorous, or plankton-eating fish, and a variety of whales (Henderson). This means that smaller filter feeding animals ingesting microplastics are also contaminating larger predators eating them. Thus, a larger, more widespread epidemic of plastics ingestion presents itself. The list of whale species found containing macroplastic, larger than 20mm, has been growing continuously and now contains 61.5% of whales (Henderson). Even tiny plastic pieces can cause problems for ocean creatures, thus the ingestion of macroplastics is even more devastating on marine life’s health. Plastics can cause obstructions with digestion, can clog necessary filters for feeding and result in starvation and death (Henderson).
Microplastic effects organisms at multiple levels throughout the ocean during the stages of breakdown associated with larger plastics. As large plastics breakdown into smaller pieces near the surface, zooplankon and other fish ingest some of the microplastics created (Wright). The rest of the smaller pieces slowly settle towards the ocean bottom due to a high density of polymers (Wright). Between the water’s surface and the sediment on the ocean floor, other organisms such as crabs or other filter feeding animals ingest some of the microplastics. Once on the ocean floor, the microplastics are also either ingested there or ocean creatures feed on the smaller organisms that had already ingested microplastic. Once in the sediment of the ocean floor, the microplastics can be ingested by sediment dwelling organisms such as lugworms (Wright).
At each depth level throughout the ocean plastics are effecting a multitude of organisms, both directly and indirectly. Side effects of plastic ingestion range from internal and external abrasions and ulcers, and blockages in the digestive tract resulting in satiation, starvation or physical deterioration (Wright). These ailments can lead to reduced reproductive ability, drowning, weakened predator avoidance, deficiency in an organisms’ ability to feed itself, transfer of damaging toxicants and in some cases, ultimately, death (Wright). All these conditions are all repercussions of the increasing pollution in ocean ecosystems. As humans increasingly impose on marine life, the obviously effects of pollution are becoming more and more serious. Plastics are just one facet of the extremely expansive pollution problem plaguing ocean life today. Pollution is an epidemic that needs to be addressed and combated vigorously, for the benefit of all ocean life.
Henderson, Lis. “Tiny Plastic Pieces Accumulate in a Huge Marine Filter feeder.” Oceanbites. University of Rhode Island, 01 July 2015.
“Ocean Issue Briefs:Toxic Pollution.” Ocean Briefing Book. Seaweb, 2016.
Wright, Stephanie L., Richard C. Thompson, and Tamara S. Galloway. “The Physical Impacts of Microplastics on Marine Organisms: A Review.”Environmental Pollution 178 (2013): 483-92. Elsevier, 13 Feb. 2013.