The effect of oscillatory flow on the orientation of V. convallaria

Microscopic sessile suspension feeders (MSSFs) are microscopic protists that live attached to aquatic debris and other underwater surfaces. MSSFs play a role in carbon sequestration, bioremediation, and the overall health of the aquatic environment they reside in by consuming bacteria and debris. Vorticella convallaria are a common MSSF found in many environments, making them excellent models to study. V. convallaria generates a feeding flow using cilia. Previous work shows that the feeding rate of V. convallaria in unidirectional flow is strongly affected by its orientation relative to the flow and the surface of attachment. V. convallaria can also be pushed by this flow towards orientations that are unfavorable for feeding. However, these results do not accurately reflect all of the flow conditions experienced by V. convallaria, such as the oscillatory flow of waves. We, therefore, determined the effect of oscillatory flow on V. convallaria. To create such flow conditions, slides with V. convallaria were placed into a rectangular flow chamber, and a syringe pump generated oscillatory flows of varying speeds and frequencies designed to mimic natural environments. We recorded both the top and side views of the organisms in these flows and determined the 3D orientation of the V. convallaria.