Capture, ingestion, and egestion of microplastics by suspension-feeding bivalves: a 40-year history

Abstract

In aquatic environments, suspension-feeding bivalve molluscs are exposed to a manifold of natural and anthropogenically derived particles, including micro- and nanoplastics. Plastic particles interact with feeding and digestive organs and can produce negative effects. As a result of these effects and the potential transfer of microplastics to higher trophic levels, including humans, there has been renewed interest in the ingestion of plastic particles by different species of bivalves. Many recent studies, however, have ignored the ability of bivalves to select among particles both pre- and post-ingestively. Neglecting to consider the factors that mediate particle capture, ingestion, and egestion can lead to erroneous data and conclusions. This paper outlines the current state of knowledge of particle processing by bivalves, and demonstrates how it relates to studies utilizing plastic particles. In particular, the effects of particle size, shape, and surface properties on capture, preferential ingestion, post-ingestive sorting, and egestion are summarized. The implications of particle selection for the use of bivalves as bioindicators of microplastic pollution in the environment are discussed. Only through a full understanding of the types of plastic particles ingested and egested by bivalves can internal exposure, toxic effects, and trophic transfer of microplastics be assessed adequately.

DNA from mollusc shell: a valuable and underutilised substrate for genetic analyses

“…Bivalve molluscs have been widely used for coastal monitoring anthropogenic aquatic contaminants such as heavy metals (Goldberg et al, 1978;Azizi et al, 2018), micro plastics (Ward, Rosa & Shumway, 2019) and human pathogen transmission (Gyawali et al, 2019;Razafimahefa, Ludwig-Begall & Thiry, 2019) together with seasonal ecotoxicological problems such as algal blooms (Gibble, Peacock & Kudela, 2016;Hinder et al, 2011). Their shells have also been used for almost four decades as a proxy to determine exposure to heavy metal concentrations in modern samples (Yap et al, 2002;Koide, Lee & Goldberg, 1982), historic (Wing et al, 2019) and archaeological samples (Binkowski et al, 2019).…”

Microplastics, microfibres and nanoplastics cause variable sub-lethal responses in mussels (Mytilus spp.)

“…The blue mussel (Mytilus edulis) and Mediterranean mussel (Mytilus galloprovincialis) have been widely used in assessing the risks posed by environmental stressors (Farrington et al, 2016;Viarengo and Canesi, 1991). Mussels are omnivorous suspension feeders with proven capacity for consuming microplastics (Ward et al, 2019a). Numerous field-studies have demonstrated that mussels can readily consume microplastic debris under environmental conditions (De Witte et al, 2014;Li et al, 2018;Li et al, 2015;Rochman et al, 2015;Santana et al, 2016;Van Cauwenberghe and Janssen, 2014;Zhao et al, 2018).…”

Impacts of microplastic vs. natural abiotic particles on the clearance rate of a marine mussel

“…Top is a summary of two-way ANOVA of the effect of abiotic particle type and concentration on mussel CR. Microplastics may reduce CR at high concentrations as a result of unique surface properties that affect the filtration process (Ward and Shumway 2004;Rosa et al 2017;Ward et al 2019). Abiotic proportion is the concentration of abiotic particles (MP or silt) divided by the total particle concentration.…”

“…Smaller MP and silt are similar in many characteristics, including size, and lack of nutritional value. Capturing and processing nutrient poor particles can reduce a mussel's energy budget by increasing feeding costs (sorting abiotic particles) or inducing a false sense of fullness, ultimately leading to less energy allocated to maintenance and growth (Widdows and Johnson 1988;Ward et al 2019). Silt has been shown to both positively and negatively affect mussel clearance and growth, creating uncertainty in how mussel CR will respond to similar abiotic particles, like MP (e.g., Bayne et al 1987;Denis et al 1999;Ward and Shumway 2004).…”