Marine debris is any man-made object that enters the coastal or marine environment. From the tiniest piece of plastic to giant free-floating fishing nets, ocean pollution causes many challenges for animals in the wild. This debris may enter the oceans through a variety of avenues including direct addition or indirect sources when it is washed out to sea via rivers, streams and storm drains.
Marine debris impacts all aspects of life. Animal health and safety are major concerns as animals become entangled in discarded waste or ingest foreign objects mistaken for food. In addition to the effects on animal well-being, ocean pollution presents problems for fishing industries, human health and safety, and provides an unappealing view of our world’s most precious resource. The impacts on the world’s economy and biodiversity are detrimental to life as we know it.
A garbage patch is an area of marine debris concentration. There are two garbage patches located in the North Pacific Ocean. These large accumulations of trash are composed of many different kinds of debris, much of which is comprised of small bits of floating plastic from land and ocean based sources. Ocean currents and circulation patterns trap the material in a cyclone of water creating large areas of ocean trash. Garbage patches can form in the open ocean or in areas closer to land where marine life is prevalent. Because the ocean patterns alter annually and change in response to environmental factors such as El Niño, the size of these garbage patches and exact location do not remain stagnant. The characteristics of each garbage patch changes in response to ocean conditions making it difficult to determine their true ecological footprint.
The Great Pacific Garbage Patch is comprised of marine debris brought together by slow moving ocean currents. The patch’s size is not known but some scientists estimate it to be twice the size of Texas and weighing approximately 3.5 million tons. Approximately 80% of the marine debris comprising the garbage patch comes from land that is washed into the Pacific Ocean with 20% entering the ocean from cargo, fishing and other oceangoing ships that spill their contents. Though the Great Pacific Garbage Patch is a large conglomerate of trash in the ocean, it is not the only place marine debris exists in the Pacific. Currently, some islands in the Hawaiian archipelago are covered with piles of trash up to 10 feet deep. The Great Pacific Garbage Patch continues to grow on a daily basis and will eventually land ashore bringing its contents with it.
Trash in the ocean kills more than one million seabirds and 100,000 marine mammals and turtles each year through ingestion and entanglement. Plastics and fishing gear greatly contribute to the problem.
Some of the most common types of marine debris are plastics. Plastics are very prevalent in our society and they come in many different kinds of shapes and sizes. Every hour, Americans use 4 million plastic bottles, yet only 1 out of 4 is recycled. When items are thrown away, they end up in either a landfill or the ocean. Plastics were designed to last and they take an incredible amount of time to biodegrade, approximately 400 years! Ocean trash takes longer to biograde than trash in a landfill because the water is cold and does not receive the same intensity of sunlight which is instrumental in degradation. Though many plastics will degrade into tiny pieces, most never completely disappear. In fact, over 46,000 pieces of plastic debris float on every square mile of ocean. These microplastics will continue to cause harm in the marine ecosystem because they intermix with plankton that are then
consumed by animals feeding in the ocean.
Lures, monofilament line, hooks and other fishing equipment creates major problems for marine life. Many animals swallow these objects while they mistake it for food or become entangled in fishing line that has been left behind. Researchers believe it will take 600 years for monofilament fishing line to biodegrade in the ocean.
Some of the most detrimental forms of pollution left behind by fisherman are ghost nets. Whether done so intentionally or unintentionally, commercial fisherman leave large fishing nets, sometimes miles in length, out at sea. When these nets are lost, they continue to fish, catching anything that is in its path that cannot escape through the mesh. This results in the entanglement of thousands of animals that either view the nets as food, shelter or accidently swim into them.
Unfortunately, most of us have seen common litter wash upon the shoreline but have you ever seen anything unusual like a home appliance on the beach? Ever encounter a refrigerator floating by as you traveled by boat to a remote fishing spot? It is not uncommon to find large pieces of equipment that have been dumped at sea or are carried there by a natural phenomenon. As we experience more extreme weather, our oceans are becoming dumping grounds for construction materials carried to the sea after hurricanes, floods and tsunamis. These items such as washers, dryers, refrigerators and the like create a different level of environmental concern. Under the influence of sunlight, wave action and mechanical abrasion these appliances simply break down slowly into ever smaller particles but they do not biodegrade like natural materials and usually contain harmful chemicals.
Marine debris poses a deadly threat to marine and coastal ecosystems. Hundreds of thousands of sea turtles, seabirds and marine mammals are killed annually when they ingest or become tangled in plastic debris. Plastic bags floating through the water resemble jellyfish, a favorite meal for a sea turtle. Fishing lures, hooks, and lines can be swallowed and cause internal injuries. Looped debris such as six-pack rings, rubber bands, packaging material and discarded fishing nets can cause entanglement issues for a variety of marine species.
When animals ingest foreign objects they may suffocate or die of starvation. Six-pack rings stunt animal growth and cut into their skin causing injuries. Ghost nets entangle marine life causing them to drown. As trash continues to accumulate in our oceans, these threats continue to grow as well. Marine animals are constantly faced with challenges from pollution that make it difficult to survive in the wild.
Take Action Against Ocean Pollution
Marine debris can seem like an overwhelming problem but there are simple steps you can take to help keep our oceans clean.
Marine Mammal Center www.marinemammalcenter.org
NOAA: Marine Debris www.marinedebris.noaa.gov
Northern Illinois University:Plastic Facts www3.niu.edu/recycling/alum_facts/page4.html