Ocean School
Environment - Plastics and Marine Life
Plastics are hailed as one of the greatest advances of our times, and indeed, advances in medicine and technology would be impossible without them. However, the very characteristics which make plastics so desirable – particularly their light weight and their stability, make them one of the deadliest substances in the marine environment. Plastics also have extremely long persistence times in marine environments. Styrofoam cups can take 50 years to degrade, six-pack rings upwards of 400, and fishing lines even longer – depending on environment! Plastics floating below the surface are less subject o UV radiation, and may persist for a thousand years. Unlike chemicals, plastics kill by mechanical action – and because of their stability they can kill again, and again and again… The three modes of death are ingestion, entanglement leading to drowning or starvation, and cutting or strangulation secondary to entanglement.
Gannet ensnared by balloon.
Image and caption courtesy of the Ocean Conservancy http://www.oceanconservancy.org
Ingestion remains the biggest issue for marine species feeding on drifting (planktonic) organisms which floating plastics strongly resemble. Sea turtles, especially leatherbacks which preferentially feed on jellyfish, are especially vulnerable, with plastic bags and balloons (especially foil-coated or made out of Mylar) being their biggest killers. Styrofoam is especially deadly for juvenile sea turtles since it degrades into tiny floating pebbles which the small turtles gobble up only to die. Other deadly items include packing bands, foam and plastic pellets, bottles, plastic shards, and many more. After ingestion, plastics simply accumulate in the digestive tract of animals, increasingly filling and finally obstructing it, which invariably leads to death. Sadly most plastics do not even degrade in the digestive system of animals. Having killed one animal many will eventually float free of the carcass to kill again.
Stomach contents of Loggerhead seaturtle (Florida) killed by marine debris (rubber grommet wrapped with plastic, plastic ball point pens and clothes-pin, p.of rubber sponge, p.of torn netting, plastic bottle, plastic strapping, numerous p.of plastic shards, bags and polypropelyne rope).
Image and caption courtesy of the Turtle Hospital.
Marine life can also die from entanglement in plastics such as string, the infamous six-pack rings, and floating lines. This is the biggest issue for animals which dive after their prey. In a dive, fins, flippers, or wings are frequently folded back against the body. If the animal dives through a tangle of marine debris in that position, its appendages will be tied back against the body, and the animal will fail to surface and drown if it is air-breathing, or will sink to the bottom and suffocate if it is gill-breathing. Even a partial entanglement will often restrict the hunting or most cruelly the eating ability of the animal, leading to death by starvation. An animal which fights for its life will often die by strangulation. And finally if the material is thin and strong enough, as for example kite string, it can actually severely cut the animal in its struggle to free itself.
Turtle badly cut and killed by string.
Image and caption courtesy of the Ocean Conservancy http://www.oceanconservancy.org
When we think of marine debris, we most often think of the open ocean dumping of waste, especially medical waste, which today only continues to occur in certain third-world countries. And indeed this problem was significant enough that an international treaty prohibited the intentional discharge of all plastics into the ocean in 1978, but we are still dealing with its legacy and will continue to deal with it for the next millennium unless we find a way to remove from the oceans what we have dumped into them. And then there is gear lost or discarded by fishing vessels which has an absolutely horrifying impact as ‘ghost nets’, and the items lost from commercial shipping, including containers with contents, lines, and deck gear such as gloves, boots, buckets, and other things.
Seal caught in and killed by a plastic strapping band.
Image and caption ©California Coastal Commission. Used with permission. http://www.coastal.ca.gov/publiced/marinedebris.html
But we often fail to see that every single one of us contributes to plastic waste that eventually ends up in marine environments. Styrofoam is found in cheap coolers, coffee cups, packing materials, and some water toys. Any one of those items that we use and loose on a beach or a river bank will end up in the ocean where it will disintegrate and go on to kill hundreds of organisms. Even the innocent-looking dock floats used in lakes will, if they are made of Styrofoam, eventually fall apart into the dangerous little white pebbles. Buckets, shovels, balls, and beach toys can also become dangerous marine debris as they become brittle from UV radiation and fall apart into the multi-colored shards which appear to be so attractive to marine life. Kites which are flown from the beach and lost with part of their string still trailing are especially dangerous, since kite string is essentially high-strength monofilament fishing line and can cruelly entangle marine life. Balloons, small inflatable balls or other water toys, and pieces of foam toys all are deadly to marine life. Never, ever let a balloon get away from you! And finally there is the plastic packing material which companies are so fond of using – plastic wrap, plastic bags, plastic trays…
Common snapping turtle, at least 15 years old. Crawled into a plastic bottle ring as young, her shell then constriced by the ring. Spinal cord partly unprotected. Image and caption ©Dino Ferri. Used with permission. http://www.auduboninstitute.org/zoo/index.htm
Even if we dispose of plastics properly in the trash, this is no guarantee that they will not end up in the ocean. Many plastics are light and can easily get blown off garbage barges, landfills, or trucks into the water somewhere from where they will get washed into the sea, or birds or wildlife will pick them up and transport them near the ocean. Remember, plastics persist for hundreds of years – that’s a lot of chances to make it into the ocean!
The solution: avoid unnecessary plastics. There is a reason why your calculator, your computer, or the inside of your car are made out of plastics. There is no reason for your cookies to be packaged in a plastic tray inside of plastic wrap. Actively choose reusable instead of disposable products. Buy in bulk or items packaged in cardboard or paper. Don’t use anything made out of Styrofoam. Several years ago consumers in Europe effectively protested plastic packaging by unpacking their purchase in the store and leaving the plastic mess for the store to clean up. This eventually resulted in a country-wide packaging reduction and recycling effort as companies were forced to pay for the disposal of their packaging materials.
In order to keep plastics from getting away from you in the environment take food out of disposable packaging at home and take it to the beach in reusable containers. Count your kid’s beach toys and collect them at the end of the day, even if they are broken. Always take home what you brought outside and especially to the shore.
Even if plastics finally seem to disappear, they are never completely gone as scientists discovered this year. They simply get ground down into a very fine powder, which now enters much smaller organisms – causing yet unknown effects.
More Information:
Global Marine Litter Information Gateway
http://marine-litter.gpa.unep.org/
Marine Debris in the News:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/3691749.stm