Agathe Bour, Ane Haarr, Steffen Keiter, Ketil Hylland,

Environmentally relevant microplastic exposure affects sediment-dwelling bivalves,

Environmental Pollution, Volume 236, May 2018, Pages 652-660, ISSN 0269-7491,

Abstract:
Most microplastics are expected to sink and end up in marine sediments.
However, very little is known concerning their potential impact on
sediment-dwelling organisms.
We studied the long-term impact of microplastic exposure on two
sediment-dwelling bivalve species.
Ennucula tenuis and Abra nitida were exposed to polyethylene microparticles at
three concentrations (1; 10 and 25 mg/kg of sediment) for four weeks.
Three size classes (4–6; 20–25 and 125–500 μm) were used to study the
influence of size on microplastic ecotoxicity. Microplastic exposure did
not affect survival, condition index or burrowing behaviour in either
bivalve species. However, significant changes in energy reserves were
observed. No changes were observed in protein, carbohydrate or lipid
contents in E. tenuis, with the exception of a decrease in lipid content
for one condition. However, total energy decreased in a dose-dependent
manner for bivalves exposed to the largest particles. To the contrary,
no significant changes in total energy were observed for A. nitida,
although a significant decrease of protein content was observed for
individuals exposed to the largest particles, at all concentrations.

Concentration and particle size significantly influenced microplastic
impacts on bivalves, the largest particles and higher concentrations
leading to more severe effects. Several hypotheses are presented to
explain the observed modulation of energy reserves, including the
influence of microplastic size and concentration. Our results suggest
that long-term exposure to microplastics at environmentally relevant
concentrations can impact marine benthic biota.

https://drive.google.com/open?id=1qtbSjJ3KxG8tuLTrWDcredbW6bHP85oC
https://doi.org/10.1016/j.envpol.2018.02.006.(https://www.sciencedirect.com/science/article/pii/S026974911734472X)