Background

Humanity consumes and produces plastic at an astonishing rate; according to the Ellen MacArthur Foundation, “plastics production has surged over the past 50 years, from 15 million tonnes in 1964 to 31 million tonnes in 2014”[1].

Ignoring potential issues of misuse of resources, this consumption of plastic presents another issue: its disposal. A large proportion of this plastic enters the oceans, almost 8 million tonnes per year[2].

Data suggests that 80% of all the world’s marine pollution comes from just 20 countries[3], with the top 5 contributing more than half. Although it might be tempting to apportion the majority of the blame with these five, the plastic pollution they produce arises partly out of their own consumption but also as a result of Western consumption, with Western countries shipping their plastic waste to Asia.

The plastic enters the oceans from multiple streams and although 55% might be entering the oceans from a few countries, that leaves almost 4 million tonnes of plastic entering across the rest of the world. 

Plastics can take several hundred, if not thousands, of years to break down under the conditions present in the ocean environment. Typically, this is through UV and mechanical degradation, resulting in finer particulate matter. The mix of macro and micro plastic pollution poses different threats to marine life and the ecosystem at large. 

Death rates due to marine plastics remain excessively high. The combination of the risk of entanglement and ingestion results in catastrophically high casualty rates amongst marine life. 

After breaking down to microplastics, they pose a more insidious threat. Plastic acts as a vector for heavy metals, plasticisers, and other toxins. And, once ingested, these toxins leach into the organism, contaminating the entire food chain. 

One study showed that approximately a quarter of fish, sampled in locations in Asia and North America, had plastics and textiles debris in the digestive system[4]. Furthermore, young fish were shown to actively target plastics as a food source, affecting their physical performance and leading to an increase in juvenile deaths, which in turn decreases the breeding pool[5]. The concentration of the ingested toxins, therefore, increases up the food chain and in humans is thought to lead to some cancers, infertility, as well as immune, metabolic, cognitive and behavioural disorders.

Marine life, and specifically the feeding patterns of most marine animals, are centred around the location of phytoplankton. The major phytoplankton growth areas are along the coast, where nutrient rich water circulates back up after travelling along the sea floor, and is found up to depths of 100 metres, decreasing in concentration as the penetration of UV light decreases.

Plankton is defined as anything unable to swim against a current, where phytoplankton is a subtype of plankton. They can be considered analogous to plants as species of autotrophic photosynthesizers; the grass of the sea.

[1], [2] World Economic Forum, Ellen MacArthur Foundation and McKinsey & Company, The New Plastics Economy — Rethinking the future of plastics, 2016, (http://www.ellenmacarthurfoundation. org/publications).
[3] The New Economist, World’s worst marine polluters named and shamed, February 13th, 2015
[4] K. Gruber, New Scientist, Plastic in the food chain: Artificial debris found in fish, 25 September 2015
[5] Chelsea M. Rochman, Science, Ecologically relevant data are policy-relevant data, 03 Jun 2016