"Many of those affected by the enormous garbage swirl—like sea birds, turtles and beluga whales—can't speak for themselves. They get caught in these nets, or they swallow some of these bottle caps. Killer whales, which are kind of our mirror, our canary in the coal mine, so to speak, are ingesting all sorts of things that are affecting their health.“

                                                                Fabien Cousteau [1]

 

Impact on Marine Life

 

    Countless marine animals have been killed or harmed by marine debris primarily because they either become entangled in it, or, they mistake plastic debris for food and ingest it for example, a sea turtle ingests a plastic bag mistaking it for a jellyfish. At least 267 different species are known to have suffered from entanglement or ingestion of marine debris including seabirds, turtles, seals, sea lions, whales, and fish. [2]

 

Entanglement [2]

    The most problematic debris are fishing nets, ropes, monofilament lines, six-pack rings and packing strapping bands. Once entangled in marine debris, an animal may suffer death by drowning, suffocation, or strangulation. If not lethal, entanglement can impair an animal’s ability to swim and therefore to find food or escape from predators.

    Entanglement can result in lacerations from the abrasive or cutting action of attached debris leading to wound infection and further immunocompromise. Entanglement increases metabolism to compensate for the increased drag during swimming. This, in effect, could cause a 4-fold increase in the quantity of food an animal needs.

    Entanglement among critically endangered species such as the Hawaiian monk seal (Monachus schauinslandi) and the Right Whale has led to a decrease in breeding colonies and represents a threat to the recovery of the population. Research shows population declines in six of seven sea turtle species and in 56 species of marine and coastal birds most commonly pelicans, gannets, and albatrosses.

 

Ingestion       

                [3] (picture shows lighters inside baby albatross carcass)

 

    Many plastic items that have been ingested by marine organisms including plastic fragments derived from larger plastic items, plastic pellets, which are used as a stock material in the plastics industry, plastic bags, and fishing line. The debris may become lodged in the throat or digestive tract leading to suffocation and starvation. Upon ingestion, hazardous chemicals in and on the plastics may leach out and be absorbed into the animal’s body potentially causing toxic effects.[2]

 

Population Effects of Ingestion

    Blockage of the digestive tract with marine debris can give a false sense of fullness, causing the animal to stop eating leading to weight loss & malnutrition. Dietary dilution may occur as the intestine is occupied by marine debris reducing the gut capacity for absorption of essential nutrients. Sharp objects can damage the gastrointestinal tract leading to pain, infection, ulceration, perforation and tissue necrosis. Certain chemicals of ingested debris are thought to be carcinogenic with the rise in the number of beluga whales diagnosed with breast cancer. [5]   Likewise, with the increasing numbers of male fish and seagulls with female organs, these chemicals are thought to be estrogenic and cause hormone imbalance.[6]  BPA, in particular, has been linked with such feminization of males.[6] (please see Human Impact tab for even more information) 

    The NOAA has listed the green turtle, leatherback turtle, hawksbill turtle, kemp’s turtle and olive ridley turtle as endangered species. The loggerhead turtle has been listed as a threatened species.[7] Ingestion of plastic debris is a significant source of mortality among the youth population of the Laysan albatross. 90% of chicks surveyed among the Hawaiian islands had some plastic debris in their upper GI tract.[8] In the Midway Atoll, cigarette lighters are commonly passed from the parent albatross via bolus regurgitation onto their chicks during feeding.[9]
 

 

Damage to Coral Reefs [10][11]

    The weight of approximately 20% of derelict fishing nets recovered from the Northwestern Hawaiian Islands is attributable to broken coral fragments. Fishing gear intentionally discarded, or unintentionally lost in storms may circulate for years in ocean gyres and currents until eventually becoming snagged. Once derelict fishing gear is caught on coral reefs, it begins a cycle of destructive activity. After derelict fishing gear snags on reefs, wave action acting on the debris breaks coral heads on which the debris is held, freeing the debris to subsequently snag and damage additional corals. 

 

Ghost Fishing [13]   [14]

    Ghost nets have been described as perpetual “killing machines” that never stop fishing. Derelict fishing gear which has been lost or discarded by fishermen may continue to function in the water as a fishing apparatus on its own. A cycle ensues whereby marine organisms are captured, and, in turn, these species may attract predator species which may then also become trapped. Sadly, one 1500-meter long section of net was found that contained 99 seabirds, 2 sharks, & salmon.

 

    There are very real effects of the garbage patch on marine life.  What is clear is that the needless death and injury to these helpless animals must stop.  Please see the call to action section for ways that you can help.


 

Works Cited:

[1] Kostigen, T.M. (2008, July) The world’s largest dump: the great pacific garbage patch. Discover. Retrieved on November 25, 2010 from http://discovermagazine.com/2008/jul/10-the-worlds-largest-dump

[2] Allsopp, M.,Walters, A., Santillo, D., Johnston, P., Plastic debris in the world’s oceans. Greenpeace. Retrieved on November 25, 2010 from http://oceans.greenpeace.org/raw/content/en/documents-reports/plastic_ocean_report.pdf

[3] Image retrieved from http://vegan.volblog.at/?itemid=17087 on December 1, 2010.

[4]Laist D.W (1997). Impacts of marine debris:entanglement of marine life in marine debris including a comprehensive list of species with entanglement and ingestion records. In: Marine Debris. Sources, Impacts, Solutions. J.M. Coe and D.B. Rogers (eds.). Springer-Verlag New York, Inc., pp99-140.

[5] Derraik J.G.B (2002).The pollution of the marine environment by plastic debris: a review. Marine Pollution - Bulletin 44: 842-852.

[6] Fabien Cousteau. Retrieved on November 25, 2010 from http://www.pbs.org/engage/live-chats/04-22-2009/fabien-cousteau

[7] Casey, S., (2007). Plastic ocean: the great pacific garbage patch. CDNN. Retrieved on November 25, 2010 from http://www.cdnn.info/news/article/a071104.html

[8] NOAA (2005b). Marine Turtles. Retrieved on November 25, 2010 from http://www.nmfs.noaa.gov/pr/species/turtles/  

[9]   Derraik J.G.B (2002).The pollution of the marine environment by plastic debris: a review. Marine Pollution - Bulletin 44: 842-852.

[10] Tsukayama D. et al. (2003). Marine debris: cigarette lighters and the plastic problem on Midway Atoll. Retrieved on Nov 25, 2010 from http://kms.kapalama.ksbe.edu/projects/2003/albatross/

[11] Image retrived from http://www.oceanservice.noaa.gov/images.html#67 on December 1, 2010

[12]Donohue M.J., Boland R.C., Sramek C.M. and Antonelis G.A. (2001). Derelict fishing gear in the Northwestern Hawaiian Islands: diving surveys and debris removal in 1999 confirm threat to coral reef ecosystems. Marine Pollution Bulletin 42 (12): 1301-1312.

[13] Timmers, M.A., Kistner, C.A., Donohue, M.J. () Marine debris of the northwestern hawaiian islands: ghost net identification. Sea Grant Publication. Retrieved on November 25, 2010 from http://www.soest.hawaii.edu/seagrant/marinedebris/GhostNetIdentification.pdf

[14]Image retrieved on December 1, 2010 from http://seaplexscience.com/2009/08/16/seaplex-day-15/