The previous post explored the extent of plastic pollution in the ocean, with an introduction to the Great Pacific Garbage Patch. In this post, we will zoom further into the plastic problem, focusing specifically on its impact on marine life.
Plastics are synthetic or semi-synthetic polymers, often produced from petroleum. Their unique properties make them ideal for a wide range of applications such as packaging, building & construction, textiles, consumer products and more. While plastics have brought about many benefits to humankind, the pollution of these materials is spelling trouble. Plastics persist in the marine environment, as they are not readily biodegradable but merely disintegrate physically in those conditions (Worm et al., 2017). This physical disintegration is the result of solar UV radiation, currents and winds that break down the plastics into a variety of size categories.
Size classification of plastics (infographic by Alexander Kunz)
Impacts on marine life
Megaplastics and macroplastics, such as fishing nets and lines, may cause the entanglement of marine organisms. Marine mammals, turtles and seabirds are especially susceptible to these effects (Thushari & Senevirathna, 2020).
Plastic ingestion is another widespread problem. Chen et al. (2018) found that 84% of the plastics sampled had Persistent Bio-accumulative Toxic (PBT) chemicals exceeding threshold levels. These chemicals are either plastic additives like flame retardants, plasticizers and lubricants, or are absorbed from the surrounding seawater (Campanele et al., 2020).
With a diameter of 5mm or less, microplastics are able to be ingested by marine organisms as small as zooplankton (Law & Thompson, 2014). More than 220 species have been reported to ingest microplastics (Lusher et al., 2017), either through direct ingestion or through trophic transfer (Smith et al., 2018) leading to biomagnification. Found to remain in some marine organisms after ingestion, these microplastics can disrupt physiological processes (Law & Thompson, 2014) and have a harmful effect on organisms’ feeding ability, growth rate, reproduction process and lifespan (Botterell et al., 2019).
In the next post, we will take a closer look at the impacts of plastics on human health. Stay tuned!
Cheers,
Sarah
References
Botterell, Z.L.R., Beaumont, N., Dorrington, T., Steinke, M., Thompson, R.C. & Lindeque, P.K. (2019). Bioavailability and effects of microplastics on marine zooplankton: a review. Environmental Pollution, 245: 98-110.
Campanale, C., Massarelli, C., Savino, I., Locaputo, V. & Uricchio, V.F. (2020). A detailed review study on potential effects of microplastics and additives of concern on human health. International Journal of Environmental Research and Public Health, 17(4): 1212.
Chen, Q., Reisser, J., Cunsolo, S., Kwadijk, C., Kotterman, M., Proietti, M., Slat, B., Ferrari, F.F., Schwarz, A., Levivier, A. Yin, D., Hollert, H. & Koelmans, A.A. (2018). Pollutants in plastics within the North Pacific subtropical gyre. Environmental Science & Technology, 52(2): 446-456.
Law, K.L. & Thompson, R.C. (2014). Microplastics in the seas. Science, 345(6193): 144-145.
Lusher, A., Hollman, P. & Mendoza-Hill, J. (2017). Microplastics in fisheries and aquaculture: status of knowledge on their occurrence and implications for aquatic organisms and food safety. FAO Fisheries and Aquaculture Technical Paper: 615.
Smith, M., Love, D.C., Rochman, C.M. & Neff, R.A. (2018). Microplastics in seafood and the implications for human health. Current Environmental Health Reports, 5(3): 375-386.
Thushari, G.G.N. & Senevirathna, J.D.M. (2020). Plastic pollution in the marine environment. Heliyon, 6(8).
Worm, B., Lotze, H.K., Jubinville, I., Wilcox, C. & Jambeck, J. (2017). Plastic as a persistent marine pollutant. Annual Review of Environment and Resources, 42: 1-26.