Plastic is everywhere in our lives, and unfortunately, much of it ends up in the ocean. Most of the plastic in the ocean comes from municipal storm drains and water that flows from rivers and creeks that all eventually drain into the ocean.  Drop litter on the sidewalk or leave a plastic bottle on the creek bank while hiking and it may end up polluting the ocean. But a significant plastic in the ocean also comes from visitors leaving plastic on the beach which inevitably ends up in the water.  

According to the California Coastal Commission, marine debris is a global pollution problem that impacts human health and safety, endangers wildlife and aquatic habitats, and costs local and national economies millions in cleanup costs, wasted resources, and lost revenues. California residents and tourists love our coast and ocean, making more than 150 million visits to California beaches each year. Any even though most visitors take care to bring their trash home, the plastics that do get left behind add up fast. A recent study found more than 300,000 pieces of plastic per square mile in the North Pacific Central Gyre (sometimes referred to as the Great Pacific Garbage Patch. 

All this debris in the marine environment means hazards for animals and humans. A recent study found documented cases of entanglement or ingestion by marine animals in nearly 1,000 separate species including all known sea turtle species and about half of all marine mammal species. And most of these incidents involved plastic debris like fishing line, strapping bands and six-pack rings which can cause trouble with eating, breathing, and swimming and may have fatal results. And unless the plastic is physically removed, it will remain in the ocean forever. Plastic does not biodegrade and may continue to trap and kill animals year after year.

Birds, fish and mammals can mistake plastic for food. Debris may cause choking and injuries, and with plastic filling their stomachs, animals may have a false feeling of being full and may die of starvation. Sea turtles mistake plastic bags for jellyfish, one of their favorite foods. Ingestion of debris has been documented in 56% of cetacean species, including whales. The Laysan albatross is a sea bird that nests in the Northwest Hawaiian Islands. The adult birds collect colorful plastic debris (along with food) from the ocean to feed to their chicks. In a study of dead chicks during 97.6% were found to contain plastic.

Plastics are the most common form of marine debris. They can come from a variety of land and ocean-based sources; enter the water in many ways; and impact the ocean and Great Lakes. Once in the water, plastic debris never fully biodegrades. Yellow text in the above graphic shows sources of plastic that eventually end up in the ocean. Orange text shows ways that these plastics move into the ocean. Red text provides examples of the harmful impacts of this debris.

Marine debris is not just an issue for the surface of the ocean. Debris is also found on the deep ocean floor. An extensive survey extending down to 4,000 meters off the coast of Monterey found that debris was more common in the deeper parts of Monterey Canyon, below 2,000 feet. Found items included large numbers of plastic bags, as well as metal cans, fishing equipment, glass bottles, shoes, and tires. A study of microplastics in Monterey Bay found particles widespread throughout the water column depth range, with the highest concentration between 200 and 600 meters deep.

Marine debris can present a danger to human health as well. Nails, glass, and syringes on the beach can cause physical harm to beachgoers. Additionally, trash in our waterways can contain harmful chemicals, negatively impacting water quality. Plastic debris serves to concentrate and transport chemical pollutants into the marine food web, and potentially to human diets. A 2015 study of fish and shellfish for sale in markets found 25% of individual fish sampled in California contained human-made items in their digestive tracts. 

Read more here:  https://www.coastal.ca.gov/publiced/marinedebris.html