Life in Plastic Ain’t so Fantastic

Guest post by Louis Vassos, MEnvSci Candidate in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

Much like the Buggles’ 1980 debut album, our material preferences are well within the age of plastic. Thanks to its light weight, durability, inertness, and low manufacturing costs, our use of plastics has increased dramatically since the mid-20^th century. From bottles and toys to car parts and electronics, there is seemingly no application beyond its reach. Despite its uses and benefits, it has come under increasing scrutiny by environmentalists in recent years. In this regard, we tend to think of larger-scale and more visible environmental impacts, such as accumulation in landfills and petrochemical use in manufacturing. There has also been a significant amount of research on plastic in marine environments, usually focused on larger debris known as macroplastics. Over the past decade, however, there has been increasing concern about a new type of plastic debris in our oceans. Though its presence was first highlighted in the 1970s, we are only just beginning to realize the impact of fragments known as microplastics. As their name would suggest, they are small pieces of plastic, typically measuring less than 5mm in diameter and sorted into two distinct classifications.

Primary microplastics are manufactured to be microscopically sized and are typically used in air blasting as a paint and rust remover, as well as in personal care products as an exfoliating scrubber. This latter use has risen sharply in cosmetics and facial cleansers since the 1980s, with plastic “microbeads” replacing natural materials such as pumice and ground almonds. Regardless of application they usually enter water bodies through drainage systems, and are easily able to pass through filtration systems at sewage treatment plants due to their small size.

Microbeads in toothpaste. Retrieved from: https://blog.nationalgeographic.org/2016/04/04/pesky-plastic-the-true-harm-of-microplastics-in-the-oceans/

Secondary microplastics arise from the breakdown of larger pieces of plastic debris on both land and in water. Larger debris will typically enter marine ecosystems directly or indirectly through careless waste disposal, often being transported through river systems. Sources of transfer include coastal tourism, extreme weather events, fishing, other marine industries, and accidental spillage during transportation. Over time, a culmination of processes such as exposure to UV radiation can reduce the debris’ structural integrity, causing brittleness, cracking, and yellowing. This in turn can lead to fragmentation through abrasion and waves, and fragments will gradually become smaller over time before reaching microplastic size (Cole et al, 2011).

As Eriksen et al (2014) have estimated, there is a minimum of 5.25 trillion plastic particles weighing 268,940 tons in the world’s oceans. Microplastics account for 92.4% of this mass, and their reach has been substantial. Because of their buoyancy and durability, they have the ability to travel long distances without degrading for years. Denser plastics (such as PVC) will sink and have the potential to reach coastal sediment (Andray, 2011). Other marine microplastics will end up trapped in ocean current systems known as gyres, the most famous grouping of which is the “Great Pacific Garbage Patch” in the North Pacific Gyre. Despite what the name would suggest, it is not an island-like mass of floating debris, but is more akin to an extensive “soup” of debris difficult to see with the naked eye. At a density of 334,271 pieces/km², microplastic mass in the area was found to be 6 times that of plankton (Moore et al, 2001). 

Potential microplastic transport pathways (From Wright et al, 2013)

Densities such as this increase potential microplastic ingestion by various marine organisms, especially filter feeders, plankton, and suspension feeders. These species may mistake debris for prey based on size or colour, or passively ingest them without being selective (Wright et al, 2013). In Farrell and Nelson’s (2013) study of mussel-eating crabs, they found that it is possible for microplastics to be transferred to individuals at a higher trophic level. The large surface area to volume ratio of microplastics makes them susceptible to water-borne pollutant contamination, and can cause toxic plastic additives such as BPA and PCB to leach into the water. This debris can also act as a dispersal vector for microbial communities, including potentially pathogenic species (Jiang et al, 2018). While the ingested debris can accumulate within individuals and be transferred up the food chain, the exact effects of this are not entirely known at this point in time (Avio et al, 2017). A recent study by Lei et al (2018), however, found that microplastics can cause oxidative stress and intestinal damage in zebrafish and nematodes, and that their toxicity is closely dependent on particle size.

Intestinal damage in zebrafish caused by exposure to 1.0 mg L^-1 of different microplastic types and sizes. Photograph A shows control (top), survival (middle), and dead after exposure (bottom) zebrafish (From Jiang et al, 2018)

Fluorescent microspheres on a crab’s gill lamella transferred from ingesting mussels, each measuring 5 micrometres in diameter (From Farrell and Nelson, 2013)

          What does the future hold for microplastics? Because their effects on both marine life and humans is relatively unknown, it is important to try and prevent them from entering and accumulating within marine environments. Properly dispose of larger plastic items to prevent them from entering waterways and breaking down into secondary microplastics, and be conscious about the presence of primary microplastics in other products. Make informed decisions when buying cosmetics, and choose ones that use natural exfoliating materials. Microbead bans have already begun to be enacted in several countries, including the UK, US, Canada and New Zealand (Pfeifer, 2018). There is also the potential for future studies on topics such as the health effects of microplastic ingestion and leached additives, debris behavior within the water column, and new standardized techniques for detection and sampling (Cole et al, 2011). It is hard to say what will happen next, but the removal of these 5.25 trillion particles from our oceans will prove to be a very difficult challenge without the development of novel extraction methods.

SOURCES

Anadrady, A.L. 2011. Microplastics in the marine environment. Marine Pollution Bulletin 62:1596 – 1605

Avio, C.G., S. Gorbi, and F. Regoli. 2017. Plastics and microplastics in oceans: from emerging pollutants to emerged threat. Environmental Research 128: 2 – 11

Cole, M., P. Lindeque, C. Halsband, and T.S. Galloway. 2011. Microplastics as contaminants in the marine environment: a review. Marine Pollution Bulletin 62:2588 – 2597

Eriksen, M., L.C.M. Lebreton, H.S. Carson, M. Thiel, C.J. Moore, J.C. Borerro. F. Galgani, P.G. Ryan, and J. Reisser. 2014. Plastic pollution in the world’s oceans: more than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PLOS One

Farrell, P., and K. Nelson. 2013. Trophic level transfer of microplastic: Mytilus edulis (L.) to Carcinus maenas (L.). Environmental Pollution 177:1 – 3

Jiang, P., S. Zhao, L. Zhu, and L. Daoji. 2018. Microplastic-associated bacterial assemblages in the intertidal zone of the Yangtze Estuary. Science of the Total Environment 624:48 – 54

Lei, L., S. Wu, S. Lu, M. Liu, Y. Song, Z. Fu, H Shi, K. Raley-Susman, and D. He. 2018. Microplastic particles cause intestinal damage and other adverse effects in zebrafish Danio rerio and nematode Caenorhabditis elegans. Science of the Total Environment 619:1 – 8

Moore, C.J., S.L. Moore, M.K. Leecaster, and S.B. Weisberg. 2001. A comparison of plastic and plankton in the North Pacific Central Gyre. Marine Pollution Bulletin 42:1297 – 1300

Pfeifer, H. 2018. The UK now has one of the world’s toughest microbead bans. CNN. Retrieved from: https://www.cnn.com/2018/01/09/health/microbead-ban-uk-intl/index.html

Wright, S.L., R.C. Thompson, and T.S. Galloway. 2013. The physical impacts of microplastics on marine organisms: a review. Environmental Pollution 178:483 – 492

The problematic charismatics: Are loveable invasives getting a free pass?

Guest post by Will Brown, MEnvSci Candidate in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

In the world of animal conservation, charismatic wildlife - those loveable, huggable species like giant pandas or koalas - take centre stage. They’re the kinds of animals you see dominating news stories, books, and movies, with less-attractive species often falling by the wayside. The concept of charismatic species is tied closely to animal conservation and protection. And the public’s love and adoration for charismatic creatures plays an essential role in the success of conservation and awareness campaigns. As flagship species they become ambassadors and icons, rallying support and focusing the public’s attention (and money) on an environmental cause or conservation program.

Figure 1 A famous example of a charismatic species used as a flagship species for a conservation group, the World Wildlife Fund (WWF). (Source)

For many years, a societal bias for charismatics has been important for protecting and conserving rare and imperilled species. But what happens when a charismatic species, rather than requiring protection, is considered an invasive pest? And how does this affect the proper implementation of invasive species management and threat abatement?

A perfect example of a charismatic species as an invasive pest is wild horses, known as brumbies, in Australia. First introduced for farm work in 1788, there are now over 400 000 brumbies throughout the country. As an invasive this species causes erosion and damages vegetation with their hard hooves and overgrazing. They damage and foul waterholes and spread weeds through seeds carried in their dung, manes, and tails. As competitors with native species, they can force wildlife from favoured habitats and dominate food and water sources. There is a significant portion of the public, however, that see the brumby as an iconic Australian species that is  ’a unique equine and epitomizes the spirit of freedom’.

 

Figure 2 Feral horses threaten fragile ecosystems in Kosciusko National Park. (Source)

To manage the impacts of brumbies in Kosciuszko National Park, a plan was released in 2016 to reduce the number of wild horses by 90% over a 20-year period. The cull was to be carried out using humane control methods including trapping, fertility control and ground shooting rather than aerial shooting and roping. The management plan sparked angry protests and fierce opposition, despite warnings from scientists about the impacts of brumbies in the region. Even though government scientists declared that the horse population in the region severely degrade natural waterways and threaten fragile native alpine wildlife, hundreds of people protested the cull in Sydney and support groups downplayed the adverse effects brumbies have had on the environment. Lisa Caldwell of the Snowy Mountain Horse Riding Association was reported as saying ‘You've got to remember that the national park is 6,900 square kilometres…horses are not going to have a huge impact on those wetlands’ (www.abc.net.au).

Now almost 2 years on, backlash to the draft legislation has halted any form of management and a new amended management plan is in the works. It is reported that the amended plan includes less aggressive reduction of wild horses, with culling more likely to reduce the numbers to several thousand rather than just 600. To overcome Australia’s environment laws that require a more complete removal of wild horses, a ‘brumbies bill’ is being put forward to give recognition to the horses’ ‘cultural significance’, providing them with legal protection to remain in the park.

Now consider how an uncharismatic species is treated in a similar situation. The feral pig, generally perceived as dirty, disease-ridden and hated by farmers, also roams through Kosciuszko National Park and has very similar impacts on the environment. Feral pigs degrade natural areas through rooting up soils, grasslands and forest litter as they feed on native plants. They also spread a number of diseases and predate on a host of native animals including insects, frogs, snakes and small ground-nesting birds. Unlike brumbies however, their numbers are managed within in the park with almost no opposition.

 

Figure 3 Feral pigs populations are controlled in Australia with minimal public opposition. (Source)

In both cases there are two species found in the same location, negatively impacting the ecosystem in a similar way. For the uncharismatic species, management plans are carried out promptly and effectively. But for the charismatic species, it seems clear that societal bias can lead to strong resistance from the public and as a result, management efforts can be delayed or watered down.

And this pattern isn’t restricted to Australia. In Canada, introduced feral cats are the No.1 killer of birds, responsible for over 100 million bird deaths per year. Even with this information available, there is no widescale control programs for managing feral cat populations. In British Columbia, an exploding European rabbit population at the University of Victoria was responsible for extensive damage to fields, lawns and mature trees. When the university tried to implement a removal program, public outcry delayed efforts and the university ended up committing to using non-lethal methods for controlling the rabbit population. Meanwhile, less cute and fluffy invasive species such as America bullfrogs in BC have active population control programs with almost no objection from the public.

Based on these examples, it is clear there is a degree of favouritism when it comes to how invasive species are perceived and subsequently managed. With an obvious bias towards charismatic species, the power of public opinion can have significant impacts on invasive species control. This in turn has the potential to result in severe ecological consequences. Unfortunately, due to the complexity of the issue there is likely no single solution. The most impactful approach may be to increase the public’s awareness of the negative impacts of invasives with a focus on how these species may be damaging native wildlife. A more controversial approach may be to simply provide government scientists with greater decision-making power when it comes to wildlife management, especially for federally and state-owned lands. Adding to the complexity of the issue is how valuable are the cultural ecosystem services provided by charismatic invasives. Are the cultural benefits of invasive species as important as those provided by native species? This is an important question that should be addressed in evaluating the overall impacts caused by invasive species. Biases present in invasion biology are rarely discussed but the issues are clear. For the effective management of all invasive species, whether huggable or ugly, these biases should be recognised and carefully considered.