Microsphere counts from Oikopleura dioica houses following feeding incubations with three microsphere sizes (for each functionalized microsphere) available in environmentally relevant concentrations

Yet, the role of microbial surface properties in avoiding or enhancing predation in the ocean remains a research frontier. Appendicularians are globally abundant marine suspension feeders that capture marine microorganisms in a complex mucous filtration system.

We used artificial microspheres to test whether the surface properties of prey particles influenced selection by the appendicularian, O. dioica. Across microsphere sizes (0.5, 1, 2 and 3 µm) and concentrations (~103-106 particles ml-1), which were varied to represent realistic microbial communities, carboxylate- and amine-modified particles were handled differently by the appendicularians. The carboxylate-modified particles were enriched in the gut while the amine-modified particles were enriched in the mucous filters, leading to different particle fates.