Physical mechanisms and rates of particle capture by suspension-feeders

Abstract

Models of particle encounter efficiency borrowed from aerosol fil- tration theory have revolutionised ideas about mechanisms of suspension-feeding (a form of hydrosol filtration), although they continue to be under-utilised in generating predictions concerning feeding ecology and morphological evolution and in guiding quantitative experimentation . As a complementary tool we model encounter rate, demonstrated with parameterisations ofthe same particle-encounter mechanisms . The rate models include specific encounter geometry, absent from the prevalent efficiency indices, which is used to refine estimates of the absolute and relative effectiveness of the various encounter mechanisms . Using rate (as opposed to effi- ciency and in accord with optimal foraging theory) as the dependent variable yields very different predictions for optimisation schemes . For example, a larger collector radius reduces encounter efficiency for most mechanisms, but it either increases or leaves unaffected encounter rate . Similarly, an increase in advection velocity often reduces encounter efficiency, but it increases encounter rate for most mechanisms