EIM0008
Written evidence submitted by Plymouth Marine Laboratory
Introduction
1. Plymouth Marine Laboratory[i] (PML) is an independent company, limited by guarantee, with charitable status and a National Capability delivery partner for the Natural Environment Research Council, as well as a designated Research Councils UK research institute. PML undertakes interdisciplinary research that brings together areas of scientific expertise to address key scientific and socially relevant questions relating to the marine environment.
Executive Summary
2. This evidence is provided by a number of PML scientists and students, with key points as follows:
Inquiry Terms of Reference
Question 1: How do microplastics impact on marine plants and animals? What economic consequences could result from increased microplastic pollution in the ocean?
3. Current assessment of microplastics in our seas is hindered by technical challenges, especially determining the prevalence of microplastics of a size potentially ingestible by small marine animals. One such group of animals that is likely to be affected by microplastics are zooplankton. Within marine food webs, zooplankton are key secondary producers, aiding energy transfer from primary producers (‘plants’) to higher trophic levels such as commercially important fish larvae and small fish as well as the larger fish that in turn feed on them . Of particular concern is that the small size of microplastics means they are readily mistaken for prey and can be ingested by zooplankton, subsequently causing harm to the organisms themselves with potential impacts on ecosystem functioning and biogeochemical processes. Research at PML in collaboration with the University of Exeter, employing bio-imaging techniques, has visualised the ingestion and internal adherence of polystyrene microplastics of a range of filter-feeding zooplankton taxa (Cole, 2013). The laboratory-based research, focussing on copepods and the impact of microplastic ingestion, shows that the presence of microplastics negatively impacts upon the feeding rates of a range of copepods. This decreases their energy reserves, in turn resulting in reduced reproductive success and increased mortality (Cole, 2015). In addition, our research has shown that microplastics become encapsulated within egests of copepods such that their faecal pellets have significantly reduced densities, reduced sinking rates, and a higher propensity for fragmentation. The encapsulated microplastics can then be further transferred within food webs via the ingestion of faecal pellets by other organisms (Cole, 2016). Sinking faecal matter may therefore be a mechanism by which floating plastics can be vertically transported away from surface waters. The risk microplastics may pose to zooplankton in their natural environment is a matter of on-going concern.
4. Microplastic ingestion has been reported in a number of marine vertebrate taxa such as fish (Lusher et al., 2013; Stolte et al., 2015; Collard et al., 2015; Rochman et al., 2015), sea birds (Bond et al., 2014, Hammer et al., 2016) and marine mammals (Eriksson & Burton 2003, Bravo Rebolledo et al., 2013, Lusher et al., 2015, Besseling et al., 2015). There is evidence to suggest that marine turtles also ingest microplastics (Tourinho et al., 2010) but, to date, the majority of research has focused on their ingestion of macro-plastic– (Nelms & Duncan et al., 2015).
5. The occurrence of microplastics ingestion has been relatively well studied in commercially important fish (Lusher 2015).
6. Trophic transfer of microplastics and their associated chemicals may cause implications for higher trophic-level organisms such as seabirds, marine mammals and humans (Miranda and Freire de Carvalho-Souza, 2016). The effects are so far unknown.
7. In comparison to the natural sciences, the social and economic research on microplastics is in its infancy. Impacts on ecosystems will affect ecosystem services and the economic and social benefits that they provide. Scoping work has begun at PML (funded through the Postcode Dream Trust and Norwegian Research Council Polar Research programme (POLARPROG)) to examine the economic consequences, in the UK and globally, of marine plastics (from micro to macro-sized materials). This will review available evidence on both the direct impacts on different commercial sectors, and the impacts that are mediated through effects on ecosystems and hence on ecosystem services, their benefits and the sectors reliant on them. There is some evidence on the social and economic consequences of macro-sized marine plastics, examining direct impacts on human health and well-being (e.g. Wyles et al., 2015), the cost to the tourism industry (e.g. Ballance et al. 2000; Tudor & Williams 2006; Watkins et al., 2015), and the physical risks of getting caught in debris for, e.g. fisheries, shipping industry and tourist. Whilst this is relevant for microplastics (as macro-debris can break down into microplastics), little work has been dedicated to microplastics specifically.
8. As identified in a recent advisory report, microplastics can have an impact on a number of commercial sectors (GESAMP, 2016). For example, an increase in microplastic pollution in the ocean could have economic consequences for fisheries and aquaculture, as well as tourism, leisure and recreation and their dependant industries. As noted above (paragraphs 3-5), commercially important fish and shellfish, as well as species of wildlife importance (e.g. dolphins, whales, seals, seabirds, basking sharks) may be contaminated by microplastics through direct consumption, as well as through trophic transfer and bioaccumulation in food chains. This may reduce the availability of seafood. In the UK alone, Van der Meulen et al (2014) estimated a yearly loss of up to 0.7% of the annual income for the aquaculture sector due to microplastics. Another important consideration is consumers’ concern over the topic. If consumers perceive a risk to their health (regardless of whether scientists conclude that there is a threat to human health or not), consumer demand can be heavily reduced. However, more research is needed to 1) examine the extent of risk of microplastics to the health of commercially important fish and shellfish and their consumers, 2) understand consumers’ current perceptions and concerns about the risk of microplastics to human health via potential exposure through seafood consumption and how this could affect their purchase and consumption intentions, 3) examine the extent of risk of microplastics to key wildlife species that support tourism, leisure and recreation, and 4) current economic impacts and predictions of future impact if microplastics in the ocean continue to increase.
9. Sectors can also be economically impacted by the public image and media relating to microplastics. For instance, if water quality and beach cleanliness labels included levels of microplastics, this could influence visiting rates and thus the tourist industry. The “Beat the Microbead” campaign initiated by the North Sea and Plastic Soup foundation has made the inclusion of microplastics in cosmetics salient to consumers. In the US and Canada, for example, this has pressured producers to review and phase out the use of microplastics in their products, with further support from national policies.
Question 2: How do the main sources of microplastics differ in (a) scale of output and (b) the importance of their environmental impacts? How should these relative impacts direct policy priorities?
10. Microplastics originate from three main sources; 1) ‘macro-plastics’ that are broken down by wave action, photo-degradation by solar UV-radiation and physical abrasion (Andrady, 2011; Barnes et al., 2009) 2) industrial pre-production plastics pellets, or ‘nurdles and 3) microbeads from exfoliating cosmetics and synthetic microfibers released during the washing of clothes (Browne et al., 2011; Cole et al., 2011; UNEP, 2009). The scale of output from macro-litter is unknown but it is estimated that 4-12 million tons of plastic enter the oceans annually. It can be assumed that the majority of this will fragment into microplastics over time (PlasticsEurope, 2015). Again, it is not known how many pre-production plastic pellets are lost at sea each year but some studies have found that the number has declined over time. For example, van Franeker & Law (2015) reported a 75% decrease in pre-production plastic pellets in North Sea fulmars since the 1980s.It has been estimated that the UK population could emit between 16 and 86 tonnes of plastic per year just from facial exfoliants alone (Napper et al., 2015) and a single garment may release >1900 synthetic fibres per wash (Browne et al., 2011). Plastic debris from all three sources have been found to varying degrees within the intestines of marine vertebrates. In a laboratory setting, microplastic with microbead characteristics have been shown to negatively affect a number of invertebrates, such as zooplankton, molluscs, worms, crustaceans (Cole 2011 et al., Wright et al., 2013, Watts et al., 2014, Cole et al., 2015) and whilst experimental work using fibres is in its infancy, ingestion of rope fibres by shore crabs lead to a reduction in energy available for growth (Watts et al., 2016). Other animals with less discriminate feeding capabilities may be at greater risk of depleted energy reserves, potentially impacting on life history traits such as reproductive success. Fibres have been found as one of the main constituents of debris found in fish intestines (Lusher et al., 2013) and green turtles (Chelonia mydas) also appear to be susceptible to ingestion of synthetic fibres that are tangled amongst their main food source, sea grass (Di Beneditto and Awabdi 2014, Nelms & Duncan et al., 2015), making this an urgent area for research focus.
11. In terms of policy, the over-arching aim should be to prevent plastic waste entering the marine environment. Macro-litter from land-based activities is a major source of microplastics but reducing it is a complicated, inter-disciplinary problem requiring socio-economic considerations. More research is needed into the contribution of domestic and industrial wastewater to microplastic pollution; for example synthetic fibres likely enter the water in significant numbers from household washing machines, and policies could be put in place to prevent this. Microbeads in cosmetics are an unnecessary pollutant which could have huge environmental implications. For the consumer, there is little benefit, if any, of their presence and so removing them from the market can be seen as ‘low-hanging fruit’ in the effort to reduce plastic pollution of our seas.
Question 3: What impact could microplastics have on human health? Are there knock-on impacts for Government policies, on e.g. food standards?
12. To the authors’ knowledge, the impacts of microplastics on human health are currently unknown. Work is still being undertaken to identify potential methods of exposure to microplastics and any associated toxins. These exposure routes could include, for example, direct ingestion from products containing microplastics such as toothpaste and cosmetics, indirect ingestion such as consumption of seafood that may have ingested microplastics (either directly or indirectly through the ingestion of prey containing microplastics), and even passive exposure from contact with the sand on tourist beaches.
Question 4: Other countries, including the USA, have taken action against microbeads in personal care products. What kind of impact would a similar ban in the UK have on the environmental situation around microplastics?
13. As discussed above, microbeads are of no benefit to the consumer when non-plastic alternatives such as sand, nut shell and coffee grounds are available. Although a ban would reduce the amount of plastics entering the marine environment and thus would be an important and fundamental step to addressing the issue, it would not eliminate the problem due to the quantities already present. In addition, other forms of microplastic appear to be present in much higher quantities than microbeads; in surveys of North East Atlantic sub-surface waters, microbeads were by far the least common form of microplastic debris found (Lusher, Burke et al. 2014). Despite this, any action that reduces the use of unnecessary plastics would undoubtedly help the environmental situation around microplastics, and there is no reason why microbeads should not be banned, as long as this is not seen as the ultimate solution to the problem.
Question 5: To what extent do larger pieces of plastic in the ocean contribute to microplastic pollution, and how can this be dealt with?
14. Larger pieces of plastic litter can degrade and fragment into smaller, micro-sized particles. While exact numbers are uncertain, it is likely this pathway represents a significant flux of microplastics into the marine environment. Degradation can result from exposure to UV radiation, thermo-oxidation reactions, hydrolysis and microbial degradation. Of these, UV exposure in air, combined with thermo-oxidation, operates at the fastest rate under normal environmental conditions. Rates of degradation are retarded in sea water due to i) lower ambient temperatures, ii) biofouling, acting to shield the plastic from UV rays, iii) reduced oxygen availability and iv) UV attenuation in sea water. The latter is particularly significant for submerged plastics or plastics that have settled in deep sea sediments. Thus, rates of degradation will be fastest for plastics stranded on beaches, or floating at the sea surface. These arguments suggest that removing larger plastics from beaches and the ocean’s surface should help to reduce the flux of microplastics entering the marine environment as a result of degradation and fragmentation.
15. Marine plastic (from macro- to micro- or even nano-sized) needs to be addressed from both angles: waste management to prevent the entry of plastics into the marine environment; and the removal of existing plastics in the marine environment. Multiple actors are needed to help address both components: 1) improved waste management facilities and services, 2) manufacturing/product design to improve ease of re-use (i.e. circular economy) and/or use of truly biodegradable materials, 3) changes in policy (e.g. single-use plastic bag charges, banning the use of microbeads in cosmetics), and 4) greater public engagement, such that consumers buy appropriate materials (e.g. avoid single-use packaging or cosmetics with microplastics in them), dispose of waste appropriately or volunteer in schemes such as Fishing For Litter or public beach cleans.
16. There are numerous actions different sectors can do (e.g. see[ii]) and some research has begun to identify and evaluate them (see Wyles et al., in preparation for further discussion). For example, campaigns can both remove plastic from the marine environment and have additional educational value (that can encourage further pro-environmental behaviour). This has been demonstrated for volunteer beach cleans with the public and also the Fishing For Litter scheme that is adopted in the Southwest of England and in Scotland (Wyles et al, submitted; Wyles et al, in preparation).
Question 6: How comprehensive and certain is our knowledge about the scale of microplastics and their effects on the natural environment? What should research priorities be, and who should fund this research?
17. For many areas of the globe, we have no or very limited data on the abundance of microplastics. Furthermore, what data we do have tends to be from surface net tows performed with relatively coarse nets. These tend to miss smaller particles, and particles that reside below the surface or in seabed and beach sediment.
18. Our current knowledge about the scale of microplastics occurrence and its effects on the natural environment is by no means comprehensive. Research on the impact of microplastics on marine organisms, and consequently the health of the whole ecosystem, is still in its infancy. It is crucial that we gain more information on the prevalence of microplastics in the marine environment, their interaction with marine organisms and the consequence of ingestion of microplastics by marine organisms to the health of the organisms and their functioning within the ecosystem. The effect of toxicity to marine organisms can potentially be caused by the plastic polymer itself, the additives it contains, or by pollutants which are known to associate with microplastics after residing in the ocean.
19. Key research priorities should include:
Question 7: How effective is international cooperation around these issues, and what more can be done?
20. Environmental impact of microplastics is an issue of both national and international concern particularly with respect to the marine environment. The UK could proactively encourage European and international collaboration to develop an integrated and holistic understanding of the current and future environmental, economic, social and health impacts of microplastics in the marine environment, for example through the EU’s Horizon 2020 programme, through active engagement in the EU Joint Programming Initiative on the Oceans. International collaboration could be facilitated through the Newton fund. The Norwegian Research Council recently funded “Marine Plastic Pollution in the Arctic: origin, status, costs and incentives for Prevention (MARP3)” project is a good example of an interdisciplinary and international research project which will investigate the impact of plastic pollution, including microplastics.
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April 2016