The pattern of body angle in time for microscopic sessile suspension feeders in situ

Microscopic sessile suspension feeders (MSSFs) are unicellular protists found attached to surfaces in aquatic environments. They generate a feeding current using cilia or flagella and range from about 5 to 100 microns in cell body size. As suspension feeders, MSSFs are critical to aquatic ecosystem health. By feeding on bacteria and detritus in the water, MSSFs sequester large amounts of carbon and can contribute to bioremediation. Understanding their feeding rate is critical to understanding their impact on aquatic ecosystems. Previous work has found that the feeding rate of Vorticella convallaria (a MSSF model organism) is dependent on the interplay of flow velocity and organism angle relative to both surface of attachment and flow. Lab-cultured V. convallaria periodically reorient, an active behavior which can affect food uptake. Here we look at naturally-occurring MSSFs in their habitat to understand their behavior and determine if it matches that of lab-cultured V. convallaria. We recorded MSSFs with an in situ microscope in varied aquatic environments in the Tacoma, Washington area. We measured flow around the organisms and tracked the stalk and cell body angles relative to the surface of attachment. We then compared these to those measured in the lab.