Every year, an estimated 14 pounds of waste (mostly plastic) enters our oceans, and this number is only growing. Some of this garbage sinks, some is eaten by marine animals that mistake it for food, and some accumulates in ocean gyres.
Where Does This Pollution Come From?
The vast majority of pollutants enter the ocean due to human activity on coastlines and far inland. The main type of ocean pollution is nonpoint source pollution, which is when runoff carries waste from sources like septic tanks, vehicles, farms, livestock ranches, and timber harvest areas into the ocean. Pollution that comes from a single source, like an oil or chemical spill, is known as point source pollution. Although, these events rarely occur, they often have devastating, large-scale impacts.
What Are the Impacts?
Nutrients and Algal Blooms
Often times, it is not the substance but its concentration which determines whether it is a pollutant. As an example, the nutrients nitrogen and phosphorus are essential elements for plant growth. However, if they are too abundant in a body of water, they can cause algae overgrowth, creating harmful algal blooms. HABs, also called "red tides" grow rapidly and produce toxic effects that can affect marine life and sometimes even humans. High concentrations of nutrients in a body of water can also result in hypoxia or dead zones. When large amounts of algae sink and decompose in the water, the decomposition process consumes oxygen and depletes the supply available to healthy marine life. Many species which live in such zones either die or migrate away. As such, ocean pollution if too severe, can destroy marine habitats and evolve into a human public health issue.
Marine debris is a persistent pollution problem throughout the all of the oceans. Worldwide, hundreds of marine species are nearing extinction due to pollution from tiny microplastics, to large fishing equipment, and even abandoned vessels. Littering, storm winds, and poor waste management all contribute to the accumulation of this debris, 80 percent of which comes from sources on land. Common types of marine debris include various plastic items like shopping bags and beverage bottles, along with cigarette butts, bottle caps, food wrappers, and fishing gear. Plastic waste is particularly problematic as a pollutant because it is so long-lasting. Plastic items can take hundreds of years to decompose.
Plastic debris poses dangers to both humans and animals. Fish become tangled and injured in the debris, and some animals mistake items like plastic bags for food and ingest them. Small organisms feed microplastics and absorb the chemicals from the plastic into their tissues. This problem is extensive, as microplastics have been detected in a range of marine species, including plankton and whales. When small organisms that consume microplastics are eaten by larger animals, the toxic chemicals then become part of their tissues. In this way, the microplastic pollution moves up the food chain,potentially becoming part of the seafood that humans eat.
Garbage patches are large areas of the ocean where marine debris collects. These patches are formed by enormous, rotating currents called ocean gyres that pull pollutants into the center of the gyre. There are five gyres in the ocean: one in the Indian Ocean, two in the Atlantic Ocean, and two in the Pacific Ocean. Garbage patches of varying sizes are located in each gyre. Due to winds and currents, garbage patches are constantly changing size and shape. The debris making up the garbage patches can be found from the surface of the ocean all the way to the ocean floor.
How Can We Help Solve This Problem?
Solutions for marine pollution include prevention and cleanups. Prevention involves eliminating single-use plastic like shopping bags to shipping packaging to plastic bottles, and moving towards recyclables which can be broken down. However, changing society’s approach to plastic use will be a long and economically challenging process. Nonetheless, many countries are taking action. According to a 2018 report from the United Nations, more than sixty countries have enacted regulations to limit or ban the use of disposable plastic items.
Cleanups can reduce the amount of waste which enters the ocean as well. Although collecting waste, especially microplastics, directly from the oceans can be challenging, organized local beach cleanups and even inland cleanups can make a difference. If you would like to make a difference, make sure to participate in Environa's annual beach cleanup.