The impacts of marine plastic pollution:

It is well known that plastic entering the world’s oceans are having a huge impact on our marine life but it also has far reaching impacts on human health and the economy.

The UNEP (2014) Report, Valuing Plastics: The Business Case for Measuring, Managing and Disclosing Plastic Use in the Consumer Goods Industry, identifies that plastics finding their way into the world’s oceans costs approximately AUD$17.3 billion per year in environmental damage to marine ecosystems; and the total natural capital cost of plastic used in the consumer goods industry estimated to be more than AUD$99 billion per year. Natural capital is the term used to describe the renewable and non-renewable natural resources that companies rely on to produce goods and deliver services. When the lifespan of products and packaging is taken into account, the annualised overall natural capital cost of the consumer goods sector is $35bn, with the largest contributors being food (25%), non-durable household goods (20%), soft drinks (13%), and retail (8%).

Examples of the impacts on the economy associated with marine plastic pollution include:

  • Asia-Pacific Economic Cooperation (APEC) estimates that the cost to the tourism, fishing and shipping industries was $1.6bn (AUD) in our region alone;

  • Local authorities have to bear the cost of cleaning up plastic litter from beaches, maintaining litter traps and bins etc. The cost on local government to manage litter in NSW is a staggering $132 million p.a.

Impacts of plastics in the marine environment on our biodiversity:

  • Starvation of species due to the ingestion of large amounts of plastic;

  • The manner in which plastics absorb and bioaccumulate toxic chemicals such as PCBs, DDT and PBDEs;

  • Entanglement and injury from plastic rubbish;

  • Indirect impacts across the food chain as a result of bio magnification of plastic related pollution via the ingestion of plastic contaminated species.

In particular, microplastics have larger surface to volume ratios than other debris, potentially facilitating contaminant exchange and have been shown to be ingested by a range of organisms. While recent modelling studies show that the flux of contaminants associated with microplastics in remote areas is small compared with that from oceanic and especially long distance atmospheric transport processes, the problem is that plastics and their accumulated contaminant load are directly digested by organisms.

Particles, including microplastics have recently been found in the circulatory systems and other tissues of filter feeding organisms such as blue mussels following experimental exposure, i.e. in organisms low in the food-chain. These particles caused typical inflammatory responses. Very small (nano-size) microplastics have been shown to cross cell membranes, under laboratory conditions, causing tissue damage. Whether the presence of acid conditions or surface active digestive substances in the guts of such marine organisms can desorb and release contaminants in significant quantities to cause such effects, or whether such a response is to their physical presence or both, still remains to be answered.

Within marine food webs, plastic debris commonly serves as both a transport medium and a potential source of toxic chemicals such as polychlorinated biphenyls (PCBs), endocrine-active substances and chemicals similar to DDT (often used as an agricultural insecticide). These chemicals are known to compromise immunity and cause infertility, even at very low levels.

Australian studies

The Great Barrier Reef Outlook Report 2014 has identified marine debris and plastics as a major threat to the health of the reef. It was found that between 2008 and 2014, 683,000 items of marine debris were recovered within the marine park. According to a recent study by the ARC Centre of Excellence for Coral Reef Studies, corals digest microbeads at about the same rate as normal food. As demonstrated by the large amounts of plastic found in their guts, corals are unable to expel these fragments. Eventually, corals will starve and die when their stomachs become filled with plastic.

In addition to the manner in which plastic acts as a toxic sponge is the fact that microplastics are so small that they have the huge potential to affect virtually all marine life. "When things get that small, it targets up for 96 per cent of the world's biodiversity, which are invertebrates, to potentially start ingesting them. They can enter the bloodstream through the gut, and then they can circulate in the bloodstream directly entering cells and tissues of these animals, says researcher Professor Emma Johnston, from the Sydney Institute of Marine Science.

Marine Biologist Dr. Kathy Townsend from the Moreton Bay Research Station, University of QLD, confirms that approximately 30% of the turtles she autopsies have plastics, including plastic bags, in their intestinal tract with a further 6% killed due to entanglement. Marine turtles are particularly vulnerable to floating debris as some species of marine turtles are thought to mistake plastic bags and other similar items for jellyfish prey.

Moreover, the CSIRO has suggested that by 2050, “95% of all sea birds will have plastics in their gut". It is estimated that globally over 1 million sea birds and over 100,000 mammals die every year as a result of plastic. These creatures die through ingestion mistaking it as food or from entanglement in plastic items. Consumed debris may starve animals by preventing ingestion of food, reducing absorption of nutrients, mechanical blockage or impairment of the digestive system resulting in internal wounds and ulceration. When plastics are regurgitated as food to chicks by their parents, physical impacts and internal ulcerations are likely to lower survival rates.

Additionally, a significant number of dead whales and dolphins have been found to ingest sufficient plastics to have caused fatal blockages. In August 2000, an eight metre Bryde’s whale died soon after becoming stranded on a Cairns beach. An autopsy found that the whale’s stomach was tightly packed with 6m2 of plastic, including many plastic check-out bags. Such obstructions in animals can cause severe pain, distress and eventual death.


Author: Dave West