Preferential grazing and repackaging of small polyethylene microplastic particles (≤ 5 μm) by the ciliate Sterkiella sp.
https://doi.org/10.1016/j.marenvres.2021.105260 Summary Microplastic (MP) particles are pollutants of global concern and are ubiquitously distributed in the ocean by physical and biological processes. It has been shown that zooplankton can ingest MP yet the interaction between ciliates and MP is still mostly unknown. The discrimination and preferential uptake of MP rather than algal prey by ciliates was assessed in this study. The ciliate Sterkiella sp. was fed a diet that consisted of only Isochrysis galbana only or a mixture of the same algae and similarly sized polyethylene beads in a 1:3 ratio. Significant, preferential MP grazing was observed in the Plastic-Algae treatment, which is the first reported evidence of proto-zooplankton preferentially ingesting MP over algal food. The mixed treatment contained fecal pellets with embedded MP. Preferential uptake of MP suggests that Sterkiella sp. is capable of ingesting and then “repackaging” MP that would otherwise be too small for larger taxa. This process would thus offer a mechanism for the reintroduction of MP into different compartments of the marine food web. As a consequence, it is necessary to account for small-sized MP (<5 μm) particles, that may have additional, and yet unknown, impacts on marine food webs. HEADERS DESCRIPTION Treatment= Algae or Algae-Plastic Type= Refers to the type of particle of one pg the above treatments: Algae or Plastic. Rep= Replicateof each treatment type. Time= Sampling time in 1 hour intervals, from T0 to T3. Num= Number of particles per ml (algae or plastic).