Does pollution harm sharks?

Microplastics from global pollution are one of the most dangerous threats to aquatic life.

By Blaise Jones

One of the key byproducts of human expansion are heavy metals. No, not Metallica. Cobalt, aluminum, chrome, lead, nickel, zinc, copper, cadmium and mercury (listed from least toxic to most toxic) are all seeping into our oceans as runoff from industries.

Smoke runoff from factories, especially those from coal-burning power plants, contain all these pollutants, which are dissolved in rain as it’s formed and in turn are then rained down into the oceans. While many of these metals are not dangerous in small portions (and, in fact, some of them are necessary components of living things), the amount present in the oceans has turned them toxic. The effects include metabolic interference, mutagenesis, organ failure, neurological damage, and death.

These trace amounts of heavy metals are not just affecting sharks and other predatory fish, but they are directly affecting us as well. They pollute the fish humans eat and if too much of these metals make their way into our systems, we can suffer from the illnesses they cause as well.

Plastic oceans

Another major way sharks are affected by pollution is through plastic pollution. Plastic pollution is one of the worst things happening to our oceans for a multitude of reasons. It’s subtle, very hard to remove once it’s in there, and so easily avoided.

Images of plastic drink rings strangling animals and bags being incorrectly confused for food and consumed illustrate the damage plastic has on animals, but the real damage is done by microplastics that do not often get captured by videos and photos. Microplastics are tiny slivers of plastic so small that they can be nearly invisible to the naked eye. They are either directly manufactured and used in many body care products, such as toothpastes and body wash, or they are formed when normal plastics are eroded by the ocean. While plastic does not dissolve in water, it does break apart into smaller and smaller chunks, creating an ocean of microplastic confetti.

Microplastics causes problems when they are ingested by fish, who often confuse the manmade pollutants as natural food. Like the heavy metals, these plastics cannot be digested by fish and end up inside their digestive tract permanently. The plastics can build up in their stomachs and prevent them from digesting food, making the animals feel like they are full when, in actuality, they are starving to death.

Probably the most upsetting thing about plastic pollution is the sheer volume of plastic in the ocean. Studies have estimated that there is as much as five trillion pieces of plastic in our oceans.

How you can help

There are ways each of us can help the problems sharks face, most notably by avoiding usage of any and all disposable plastics. Use a water bottle and reusable shopping bags instead of buying bottled water and using the plastic grocery bags at the store. Avoid using disposable straws and utensils are much as you can, instead bring your own reusable ones. Make sure to properly recycle all the plastics that you do use to at least minimize the damage it can do.

Most importantly, avoid using body-care products that contain microplastics. Look for any of the following in the ingredient label:

  • Polyethylene/Polythene (PE)
  • Polypropylene (PP)
  • Polyethylene terephthalate (PET)
  • Polymethyl methacrylate (PMMA)
  • Nylon.

All of these are micro-plastics and should be avoided.

Try lowering your carbon footprint as well, as carbon pollution is the biggest source of heavy metals in our oceans. Keep your electronics unplugged when you’re not using them, and try turning off your air conditioner when you’re not home. If possible, ride a bike instead of driving a car when you go out. Try installing solar panels or wind turbines in your home.

Many of the pollution issues our oceans are facing can be fixed with a lot of time and hard work. Part of that hard work has to come from every person doing every little thing they can to minimize their impact.


  1. Eriksen M, Lebreton LCM, Carson HS, Thiel M, Moore CJ, Borerro JC, et al. (2014) Plastic Pollution in the World’s Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea. PLoS ONE 9(12): e111913. doi:10.1371/journal.pone.0111913
  2. Sazima, Ivan, Ott B F Gadig, Rafael C. Namora, and Fabio S. Motta. “Plastic debris collars on juvenile carcharhinid sharks (Rhizoprionodon lalandii) in southwest Atlantic.”Marine Pollution Bulletin10 (2002): 1149-151. Web.
  4. Laist, David W. “Overview of the Biological Effects of Lost and Discarded Plastic Debris in the Marine Environment.”Marine Pollution Bulletin 6 (1987): 319–326. Web. 23 Dec. 2016.
  5. Cliff, Geremy, et al. “Large Sharks and Plastic Debris in KwaZulu-Natal, South Africa.”Marine and Freshwater Research 2 (2002): 575–581. Web. 23 Dec. 2016.
  6. Joyner, Christopher C., and Scot Frew. “Plastic Pollution in the Marine Environment.”Ocean Development & International Law 1 (1991): 33–69. Web.
  7. Storelli, M. M, and G. O Marcotrigiano. “Persistent Organochlorine Residues and Toxic Evaluation of Polychlorinated Biphenyls in Sharks from the Mediterranean Sea (Italy).”Marine Pollution Bulletin 12 (2016): 1323–1329. Web. 23 Dec. 2016.
  8. Marcovecchio, Jorge Eduardo, Victor Jorge Moreno, and Antonio Pérez. “Metal Accumulation in Tissues of Sharks from the Bahía Blanca Estuary, Argentina.”Marine Environmental Research 4 (1991): 263–274. Web. 23 Dec. 2016.
  9. Mársico, E T, M E S Machado, and M Knoff. “Total Mercury in Sharks Along the Southern Brazilian Coast.”Arquivo Brasileiro de Medicina Veterinária e Zootecnia 6 (2007): 1593–1596. Web. 23 Dec. 2016.
  10. Ward-Paige, Christine A., et al. “Large-Scale Absence of Sharks on Reefs in the Greater-Caribbean: A Footprint of Human Pressures.”PLoS ONE 8 (2010): e11968. Web.
  11. Domeier, Michael L.Global Perspectives on the Biology and Life History of the White Shark. N.p.: CRC Press, 2012. Web. 23 Dec. 2016.
  12. Govind, Pandey. “Heavy Metals Causing Toxicity in Animals and Fishes (PDF Download Available).” 2.17 (2014): 17–23. Web. 23 Dec. 2016.


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