Microplastics in Invasive Freshwater Mussels (Dreissena sp.): Spatiotemporal Variation and Occurrence With Chemical Contaminants

Abstract

Invasive zebra and quagga mussels (Dreissena spp.) in the Great Lakes of North America are biomonitors for chemical contaminants, but are also exposed to microplastics (<5 mm). Little research has examined in situ microplastic ingestion by dreissenid mussels, or the relationship between microplastics and chemical contaminants. We measured microplastics and chemical contaminants in mussel tissue from Milwaukee Harbor (Lake Michigan, United States) harvested from reference locations and sites influenced by wastewater effluent and urban river discharge. Mussels were deployed in cages in the summer of 2018, retrieved after 30 and 60 days, sorted by size class, and analyzed for microplastics and body burdens of three classes of contaminants: alkylphenols, polyaromatic hydrocarbons, and petroleum biomarkers. Microplastics in mussels were higher in the largest mussels at the wastewater-adjacent site after 30 days deployment. However, there was no distinction among sites for microplastics in smaller mussels, and no differences among sites after 60 days of deployment. Microplastics and chemical contaminants in mussels were not correlated. Microplastics have a diversity of intrinsic and extrinsic factors which influence their ingestion, retention, and egestion by mussels, and which vary relative to chemicals. While dreissenid mussels may not serve as plastic pollution biomonitors like they can for chemical contaminants, microplastics in dreissenid mussels are widespread, variable, and have unknown effects on physiology, mussel-mediated ecosystem processes, and lake food webs. These data will inform our understanding of the spatial distribution of microplastics in urban freshwaters, the role of dreissenid mussels in plastic budgets, and models for the fate of plastic pollution.

Anthropogenically impacted lake catchments in Denmark reveal low microplastic pollution

“…Yet, Phuong et al ( 2018 ) found that larger bivalves contained more microplastic than smaller ones, whilst Doucet et al ( 2021 ) reported a negative correlation between body size of the freshwater mussel Margaritifera margaritifera L. and the number of ingested microfibers. Hoellein et al ( 2021 ) found that Dreissena polymorpha < 1 cm had significantly less microplastic per individual than organisms with a size between 1 and 2.5 cm, and when reported per gram wet weight, the size class with the highest concentration was the size class 1–1.5 mm whereas mussels < 1 cm and > 2.5 had the lowest concentration. This supports the chosen size of mussels for this study, as well as the fact that they are more numerous than larger individuals and thus are easier to sample—and they have a higher filtration rate.…”

Egestion rates of microplastic fibres in fish scaled to in situ concentration and fish density

“…We prepared particles for polymer identification as described in Barrows et al (2018) and Hoellein et al (2021). We wrapped glass microscope slides in aluminium foil and rinsed with filtered DI water.…”

Effects of elevated temperature and microplastic exposure on growth and predatory performance of a freshwater fish

“…The concentration of microplastic beads chosen to be injected into each mussel was informed by microplastic counts from quagga mussels collected from the St. Lawrence River, which ingested 2-11 microplastic particlesÁindividual À1 (Supplementary Table S2) and 2-4 beadsÁindividual À1 (Supplementary Table S3). Given that round gobies consume 30-40 dreissenid mussels daily (Naddafi and Rudstam 2014), they would be exposed to at least 18-24 microplastic particles daily from trophic transfer, assuming quagga mussel body burden is similar to that reported in the Great Lakes Basin (Hoellein et al 2021; Supplementary Tables S2, S3). To be conservative, we chose concentrations of 10 beadsÁmussel À1 as a low microplastic treatment.…”