This proposal continues work initiated to study the mechanisms of bivalve mollusc selectivity among complex mixtures of particles, living and detrital, in order to (1) develop a quantitative method using video endoscopy to sample particles within the pallial cavity and to analyze these samples by flow cytometry; (2) perform comparative studies among different bivalve feeding types; and (3) to identify limiting processing steps of bivalves (e.g., sorting of particles on the palp, processing particles through the gut) in order to form a model of bivalve particle transfer and processing within the various compartments of the pallial cavity. These results, in turn, can be used to construct an integrative model of bivalve feeding and particle processing, which can ultimately be connected to coastal ecosystem models of seston dynamics. Our previous results demonstrate that the combination of flow cytometry and video endoscopy is a powerful tool to study (a) rates of particle processing and the degree and (b) mechanisms of particle selectivity. We could demonstrate in oysters and mussels strong selection against particles of low nutritional value and effects of particle quality on processing rate. This new approach gives us an excellent assay, and we have only scratched the surface of the important problems in feeding functional ecology and effects on coastal systems that may be examined.
