Plastic in the Sea – The Sea as Trash Can

It is not just the industry that dumps wastewater into the sea. Each of us also uses the sea directly or indirectly as a rubbish bin. Our task is to limit the amount and the kind of rubbish. Most of the substances conducting into the sea cannot be reused or broken down by nature and cause soiling, destruction and in the end the death of the seas.

The marine protection organization OceanCare estimates that worldwide every hour about 1’200 tons of waste gets thrown directly into the oceans, more than 85% of it is made out of plastic. Unfortunately plastic has become almost indispensable in our daily life. However, when it is improperly disposed of and ends up in the oceans, plastic debris poses a serious threat to various marine species. Plastics decompose very slowly and this process can take a few hundreds to a few thousands of years. Six million tons of plastic waste per annum finds its way via rivers to the oceans. The heat of the sun and the salty water degrade the plastic into tiny particles which subsequently attract toxic substances. The concentration of pollutants, such as DDT or PCBs, in such plastic particles is up to one million times higher than in the surrounding water.

For many marine species, drifting shopping bags and other plastic items resemble their natural food. This is why marine animals, in particular sea turtles and sea birds, frequently ingest plastic debris. This indigestible “food” blocks the intestinal tract and leads to death through malnutrition and starvation. The animals thus die an agonizing death. The toxic waste poisons marine animals, congests their stomachs and/or sets deadly snares around their bodies. Every year, approximately one million seabirds, 100’000 marine mammals and an innumerable number of sea turtles and fish are harmed or killed by the toxic and entangling plastic debris.

Large plankton-feeding marine animals such as manta rays, whale sharks or whales filter hundreds to thousands of cubic meters of seawater each day. Thereby they absorb large amounts of micro plastic which accumulate in the digestive tract of these huge animals. Larger parts can also damage the digestive tract or block the nutrient uptake which can affect the hormone balance, the metabolism, the growth and the reproduction.

Cigarette filters for example need 200 years to be biologically degraded by nature. They are very poisonous and can get swallowed by fish what they won’t survive.

Ocean waste damages and suffocates marine habitats. On average there are 18’500 pieces of plastic per square kilometer of ocean. In some places, the amount of plastic is six times the amount of plankton which is the first essential link to life in the oceans because it is at the beginning of the food chain. Ingested plastic debris may poison marine animals as harmful substances contained in plastic may leach out and be absorbed by the animal’s body. Moreover, harmful chemicals in the environment may attach themselves to plastic debris. Therefore, the ingestion of very tiny plastic particles – either plastic pellets or broken up fragments of larger plastic items – can also be a source of hazardous substances accumulating in the marine food chain. Eventually, these chemicals wind up on our plates too. The overall effect on humans of consumption of fish that ingested plastics is still being investigated but it is obvious that it can only have a detrimental effect on human health.

Today, plastic debris is one of the biggest sources of global marine pollution. And it is not only found in areas where people live. Far out at sea, marine debris is gathered by ocean currents and bundles up as giant waste patches. In the middle of the North Pacific Ocean, between Hawaii and California, the so called Great Pacific Waste Patch has formed which is the size of Western Europe. The patch weighs an estimated three million tons, exceeding the regional plankton volume by a factor of six. The South Pacific, Atlantic, Mediterranean and Indian Oceans also contain conglomerations of plastic waste trapped in a never-ending plastic carousel.

Around 20% of the waste that is disposed of daily in the sea comes from ships, but all the rest comes directly from the mainland. Waste is also carried directly into the sea by wind, floods and rivers (even from regions far from the coast). From all this garbage the amount of plastic is immense. Every year, more than 9 million tons of plastic end up in the seas. We only see 1 percent of these 9 tons floating on the surface. Most of the rest is floating under the sea surface or is already in the deep sea, as plastic slowly sinks at some point. If this pollution by plastic continues unchanged, there will be more garbage than fish in the seas by the year 2050.

The “out of sight, out of mind” expression doesn’t work with the rubbish. Everything we throw away thoughtlessly will come back to us one day. Even if we cannot see the garbage in the sea anymore – it is still there!

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