by Lukas Szpojnarowicz –

Our oceans face many growing threats, particularly caused by the presence of plastic debris and polluting microplastics. A journal article written by Vegter et al. (2014) addresses the environmental challenge of mitigating pollution, by compiling the global research efforts of 27 marine scientists, and 196 initial research questions (rqs) – which were then reduced to 16 overarching rqs specific to mitigating plastic pollution impacts [1]. These focus on and suggest research priorities for myriad negative impacts of plastic pollution.

History of Plastic

There has been a 52900% increase in the production of plastic – from 0.5 to 265 million tons between 1950 and 2010, respectively [2,3]. Plastics are persistent, they can take over 450 years to biodegrade [4]. This, combined with its insubstantial weight and cheap cost of production, has made plastic omnipresent in all environments.

The Impacts

Out of the 16 priority rqs, 7 focus on the impacts of plastic pollution, where the majority of these are direct, as they are more readily measurable, quantifiable, and visible. Over 170 marine species have been recorded to ingest human-made polymers that could cause life-threatening complications [5] and this number is almost definitely greater. This direct impact is a critical issue, as plastics exposure is occurring at the base of the food web [6], due to the ingestion of microplastics by filter feeding marine invertebrates [7].

Plastic pollution in Ghana. Image: Muntaka Chasant, CC BY-SA 4.0 via Wikimedia Commons

The presence of plastics and fragmented debris may also reduce oxygen and light availability [8] and change temperature and water currents [9]. These will cause direct changes to marine environments, with indirect impacts on marine wildlife. These longer-term impacts of plastic pollution are not currently well understood but are likely to have drastic future effects on a population level – and be amplified by toxicological effects of plastic on: growth rates, survivorship, and reproduction [1].

The provision of new habitats for some species, such as hard surface shells for hermit crabs, may initially appear beneficial, but these act as mass murderers of this species; one study uncovered 526 dead hermit crabs in 1 wide container [10]. Furthermore, the impacts of climate change – increased sea level, global surface mean temperature, and altering ocean pH and rainfall patterns – will amplify the amount of plastic entering the ocean system by flooding waste dumps, as well as the scale of the impact the current plastic has within the ocean basin, with changing ocean current patterns. Subsequently, plastic exposure and accumulation will increase, with further damage to benthic environments (deep ocean) in particular in the future [8].

Conclusion

The quantification of global research by Vegter, (2014) has shown that an immediate and global-scale change is critical to the issue of plastic pollution [1]. This must inherently be interdisciplinary, as plastic pollution impacts on everything, from plankton to humans to coral reefs. These impacts can be direct (entanglement), indirect (change in marine environments) or predicted for the future (climate change amplification).

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References

[1] Vegter, A.C. and Barletta, M. and Beck, C. and Borrero, J. and Burton, H. and Campbell, M.L. and Costa, M.F. and Eriksen, M. and Eriksson, C. and Estrades, A. and Gilardi, K.V. (2014) Global research priorities to mitigate plastic pollution impacts on marine wildlife. Endangered Species Research, 25(3), 225-247.

[2] Thompson, R.C. and Moore, C.J. and vom Saal, F.S. and Swan, S.H. (2009). Plastics, the environment and human health: current consensus and future trends. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 364(1526), 2153-2166.

[3] Plastics Europe (2011) Plastics – the Facts 2011. ‘https://www.plasticseurope.org/application/files/1015/1862/4126/FactsFigures_UK2011.pdf’ [30.11.20].

[4] Small Business (2019) The Decomposition of Waste in Landfills. ‘https://www.thebalancesmb.com/how-long-does-it-take-garbage-to-decompose-2878033#:~:text=Plastic%20waste%20is%20one%20of,take%20450%20years%20or%20more’ [28.11.20].

[5] Müller, C. and Townsend, K. and Matschullat, J. (2012) Experimental degradation of polymer shopping bags (standard and degradable plastic, and biodegradable) in the gastrointestinal fluids of sea turtles. Science of The Total Environment, 416, 464-467.

[6] Thompson, R.C. and Olsen, Y. and Mitchell, R.P. and Davis, A. and Rowland, S.J. John, A.W.G. and McGonigle, D. and Russell, A.E. (2004) Lost at sea: where is all the plastic? Science, 304(5672) 838.

[7] Wright, S.L. and Thompson, R.C. and Galloway, T.S. (2013) the physical impacts of microplastics on marine organisms: a review. ScienceDirect, 178, 483-492.

[8] Goldberg, E.D. (1997) Plasticizing the seafloor: an overview, Environmental technology. 18(2), 195-201.

[9] Carson, H.S. and Colbert, S.L. and Kaylor, M.J. and McDermid K.J. (2011) Small plastic debris changes water movement and heat transfer through beach sediments, ScienceDirect. 62(8), 1708-1713.

[10] NRDC (2020) How plastic bottles become death traps for hermit crabs. ‘https://www.nrdc.org/onearth/how-plastic-bottles-become-death-traps-hermit-crabs’ [30.11.20].