by Scubacrowd - 05/07/2013
In Indonesia, litter has been found to cover up to 90% of shore and strandline, and around 80% of marine debris is from land-based sources. Marine debris has an impact on marine life and humans. In the Pacific Ocean there is already a garbage patch of the size of Texas.
There are four major sources of marine debris. First, as we already know, tourism has a major impact on our environment. Tourists leave their litter on the coastlines such as food and beverage packages, cigarettes and plastic beach toys. Second, there is sewage-related debris. During heavy rainfall, some litter such as garbage and street litter are directly washed into the sea or rivers. Fishing related debris can include old fishing lines and nets (so called ghost nets), fishing pots and strapping bands accidently lost or deliberately dumped in the ocean by commercial fishing boats. Last, wastes from ships and boats are accidentally or deliberately dumped into the ocean. Illegal dumping of domestic or industrial wastes into coastal and marine waters is an important source of marine debris.
Marine debris can have an important impact on marine wildlife, but also on humans. Marine life, such as turtle, fish, dolphins, whales or birds can become entangled in marine debris. Most problems come from fishing nets and ropes, monofilament lines, six-pack rings and packing strapping band. Once an animal gets entangled, it may not be able to free itself anymore and dies from drowning or suffocation. Also coral reefs can be object to entanglement in marine debris. The debris gets entangled in a coral and subsequent wave action causes coral heads to break off at points where the debris was attached. This process is repeated over and over again. Another serious problem are ghost nets. Little fish or crustaceans get entangled in the nets, this attracts bigger fish searching for prey and then the bigger fish also gets entangled. Dead organisms in the nets and pots may subsequently attract scavengers such as crustaceans and again these species may then also become trapped.
Furthermore, marine debris do harm to marine life due to ingestion. Turtles, fish or sea birds often mistake plastic bags or other floating marine debris for prey and eat the litter. The debris can be harmlessly digested, but it can also happen that it stays in their stomach. The animal either dies from harmful chemicals contained in plastics or other debris, or the debris stays in their stomach, giving the animal a false feeling of fullness and the animal dies from starvation.
Humans are also affected by marine debris. For humans there can be economic losses as well as safety problems concerning marine debris. The marine debris might do harm to ships by blocking water intakes, propellers and rudders. The reparation of the ships is expensive and over more, the debris can lead to serious safety problems. Tourism might as well be affected by the marine debrisas shore debris are a big aesthetic problem on beaches as discourages tourists form swimming and visiting the spot. Therefore economic losses can be foreseen.
Marine debris can be found in different places. First floating marine debris is swimming in different areas of the marine environment. Generally, up to 10 items of debris can be found per square kilometer of ocean. Seafloor debris instead can be found in European waters, in the USA, the Caribbean and in Indonesia. Shoreline debris is predominantly a problem in Indonesia and Sicily where up to 231 items per meter of shoreline can be found.
Another problem is trash vortex. A vortex known as the Great Pacific Garbage Patch is an area of the size of Texas in the Pacific Ocean where an exceptionally high concentration of pelagic plastics, chemical sludge and other debris can be found. Marine debris gets accumulated in this area due to currents. For every kilo of natural plankton an estimated six kilos of plastics can be found there. The garbage swirls around along with dead fish and other marine life. Due to the good stability of plastics, the Great Pacific Garbage Patch will probably not be degenerated for centuries.
In general, plastics consistently make up 60 to 80% of all marine debris. Plastic floats and travels thousands of miles around the ocean. We use plastics because it is cheap and durable. But the highly estimated durability can be fatal. As the plastic is resistant to natural biodegradation processes, it either stays in its original form or gets broken into smaller fragments over time. The plastics and plastic particles can be found ingested by marine life.
Photos: CC - BY - NOAA's National Ocean Service
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