GBF Winter 2022 Newsletter

Kennedy Bucci picks up plastic litter samples Pictures: Bucci et al. 2021 ET&C (DOI: 10.1002/etc.5036) Normal Minnow Some Deformities IT’S NOT JUST PHYSICAL STUDY FINDS COMPLEX CHEMICAL MEAL OF MICROPLASTICS CAUSE UP TO 6X MORE DEFORMITIES IN MINNOWS. Tiny pieces of plastic, some invisible to the naked eye, have been accumulating in the environment for decades. Some breakdown from larger pieces of litter, others are manufactured to be in the small size range. These pieces of plastic are called microplastics, but despite their tiny size, they can have big impacts in the environment. The complexity of microplastic types, shapes, sizes, and chemical cocktail is often overlooked in the study of the effects of microplastics. Many studies investigate how ‘virgin’ microplastics affect organisms, typically using commercially-available polyethylene (PE) or polystyrene (PS) micro-spheres. Although these studies are useful to inform how organisms ingest and excrete microplastics, their effects are difficult to translate to how microplastics truly affect wildlife. In my research, we wanted to compare the effects of microplastics found in the environment to commercially-available ‘virgin’ microplastics. In the aquatic environment, ‘microplastic pollution’ exists as a complex mixture of plastic particles of different sizes, shapes, colours, and types. The types of particles that make up the mixture, as well as howmuch is present, also differs by region and even by when the sample was collected. Plastic pollution also has an associated suite of chemicals, called a chemical cocktail. This cocktail is made up of additives from manufacturing, unreacted monomers from the polymerization process, AND environmental contaminants sorbed from the surrounding environment. These chemicals, once they have concentrated on or within the plastic, are ingested by wildlife, providing an additional vector for these contaminants to enter the food web. Thus, plastic pollution poses both a physical and a chemical threat to organisms. To compare the effects of microplastics found in the environment to commercially available microplastics, we collected polyethylene (PE) and polypropylene (PP) plastic pollution from the shore of Lake Ontario, the most polluted of the Great Lakes. Our goal was to better understand the importance of the chemical cocktail in causing harm to wildlife. To conduct this study, we used fathead minnows (Pimephales promelas), which are a prey species commonly found in lakes and rivers throughout North America. Fathead minnows are prey to larger sportfish including perch, walleye, and northern pike. We chose PE and PP for our experiment because they are commonly produced and polluted. PE is the most widely used plastic type, and is used in food packaging, shopping bags, and products like chairs and snowboards. PP is stronger and more flexible than PE, and is used to produce car parts, medical devices, and food containers. PE and PP already have chemical additives from the manufacturing process, such as plasticizers and antioxidants, that give the products desired properties like flexibility and durability. The plastics collected from Lake Ontario likely have an additional suite of contaminants that are found in Lake Ontario, such as polychlorinated biphenyls (PCBs), organochlorine pesticides (like DDT), and heavy metals like arsenic, mercury, and lead. What my study did: • We exposed minnows to microplastics and their associated contaminants for a total of 14 days, from the egg stage into the larval stage, through the crucial development period. We observed their survival rate, length and weight, and the number of deformities. • And, to understand the chemical dimension of microplastics, we used a unique experimental design. In one treatment, we exposed organisms to the plastic particles after soaking in water for 24 hours, to look at physical and chemical effects together. In the second treatment, we soaked particles for 24 hours, but then sieved the particles out and exposed the fish to only the leachates. The results of our study give two main conclusions. First, microplastics from the environment caused almost 6x more deformities in larval fatheadminnows compared to the microplastics purchased from a manufacturer. Washing machine filters are one practical solution to preventing microplastics (mostly in the form of microfibres) from entering the aquatic environment. Read on to see the results of GBF’s and the University of Toronto’s Parry Sound Washing Machine Filter study. By guest writer Kennedy Bucci. Kennedy Bucci is a PhD candidate in the Rochman Lab at the University of Toronto. Her research investigates the effects of microplastics in freshwater ecosystems, looking at multiple levels of biological organization, from cells to ecosystems. Kennedy is also an avid reader, and loves hiking, foraging, and being outdoors. Second, we saw deformities in both the leachates only and the particles+leachates treatments. This suggests that the chemical component of microplastics does matter — it wasn’t just the physical particles causing these deformities. While more research is needed to further understand the role of chemicals in microplastic pollution, we know that microplastic pollution is harmful to the wildlife of the Great Lakes. Policy measures that prevent plastic pollution from reaching the Great Lakes is critical — we will never solve the problem with beach cleanups alone. GBF.ORG | WINTER 2022 | 3

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