Meeting Abstract

25.3  Wednesday, Jan. 4  Microscopic filter feeders near boundaries: feeding restrictions and strategies due to eddies PEPPER, Rachel E.*; ROPER, Marcus ; RYU, Sangjin; MATSUDAIRA, Paul; MATSUMOTO, Nobuyoshi; NAGAI, Moeto; STONE, Howard A.; University of California, Berkeley rachel.pepper@berkeley.edu

Microscopic sessile filter feeders are an important part of aquatic ecosystems and form a vital link in the transfer of carbon in marine food webs. These filter feeders live attached to boundaries, consume bacteria and small detritus, and are in turn eaten by larger organisms. Such filter feeders survive by creating a feeding current that draws fluid towards them, and from which they filter their food of interest. We show using calculations, simulations, and experiments that eddies form near these feeders as a result of fluid forcing near a boundary. The extent of these eddies, and their effect on the nutrient uptake of the organism depend on the angle of fluid forcing relative to the boundary. We show through calculations that feeding at an angle greatly increases the feeding efficiency of model filter feeders with perfect nutrient capture efficiency in the absence of diffusion. We also show experimental data that cultured filter feeders feed at an angle to the substrate. We discuss the effects of nutrient diffusion and inefficient nutrient capture on our model, as well as a possible mechanism for filter feeders to change their orientation.