The physical impacts of microplastics on marine organisms: A review

Plastic debris at the micro-, and potentially also the nano-scale, are widespread in the environment. Microplastics have accumulated in oceans and sediments worldwide in recent years, with maximum concentrations reaching 100 000 particles m3. Due to their small size, microplastics may be ingested by low trophic fauna, with uncertain consequences for the health of the organism. This review focuses on marine invertebrates and their susceptibility to the physical impacts of microplastic uptake. Some of the main points discussed are (1) an evaluation of the factors contributing to the bioavailability of microplastics including size and density; (2) an assessment of the relative susceptibility of different feeding guilds; (3) an overview of the factors most likely to influence the physical impacts of microplastics such as accumulation and translocation; and (4) the trophic transfer of microplastics. These findings are important in guiding future marine litter research and management strategies. -- Highlights: •Accumulation of plastic waste in the oceans has become a pressing issue. •Here we review the susceptibility of marine invertebrates to microplastic uptake. •Size, shape and abundance influence uptake; microfibres are considered most harmful. •Colonisation of microplastics could have population-level impacts. •Results will inform future marine litter research and management strategies. -- Here we review microplastic uptake in marine organisms and assess individual, population and community level effects, highlighting the most susceptible species