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Microplastics Alter the Properties and Sinking Rates of Zooplankton Faecal Pellets
journal contribution
posted on 2016-02-23, 14:57 authored by Matthew Cole, Penelope
K. Lindeque, Elaine Fileman, James Clark, Ceri Lewis, Claudia Halsband, Tamara
S. GallowayPlastic
debris is a widespread contaminant, prevalent in aquatic
ecosystems across the globe. Zooplankton readily ingest microscopic
plastic (microplastic, < 1 mm), which are later egested within
their faecal pellets. These pellets are a source of food for marine
organisms, and contribute to the oceanic vertical flux of particulate
organic matter as part of the biological pump. The effects of microplastics
on faecal pellet properties are currently unknown. Here we test the
hypotheses that (1) faecal pellets are a vector for transport of microplastics,
(2) polystyrene microplastics can alter the properties and sinking
rates of zooplankton egests and, (3) faecal pellets can facilitate
the transfer of plastics to coprophagous biota. Following exposure
to 20.6 μm polystyrene microplastics (1000 microplastics mL–1) and natural prey (∼1650 algae mL–1) the copepod Calanus helgolandicus egested faecal
pellets with significantly (P < 0.001) reduced
densities, a 2.25-fold reduction in sinking rates, and a higher propensity
for fragmentation. We further show that microplastics, encapsulated
within egests of the copepod Centropages typicus,
could be transferred to C. helgolandicus via coprophagy.
Our results support the proposal that sinking faecal matter represents
a mechanism by which floating plastics can be vertically transported
away from surface waters.