Jumars, P. A. University of Washington, jumars@ocean.washington.edu
Mayer, L. W. University of Maine, lmayer@maine.maine.edu
Vetter, Y. University of Washington, yav@u.washington.edu
Schmidt, J. University of Washington, jills@ocean.washington.edu

 
CONTRASTING CHARACTERISTICS AND CONSEQUENCES OF DIGESTION BY DEPOSIT FEEDERS AND SEDIMENTARY BACTERIA
 
Deposit feeders process large volumes of particles quickly. They use various operating policies to achieve net gain on this dilute resource. One is control of adsorption through secretion of surfactants. Another is control of fluid residence times through management of luminal solute transport. Intensive digestion employs freely diffusing, dissolved enzymes that afford access to particulate, adsorbed and dissolved food within the container of the gut lumen. Feeding is more or less continuous. At any one time, spatial distribution of deposit feeders is generally non-uniform; the animal's net gain increases nonlinearly with increasing food quality. Sedimentary bacteria, on the other hand, appear to depend on proximity of particulate material and must use tightly adsorbing enzymes in order to achieve net gain of dissolved products. Allowing enzymes to diffuse away freely in solution fails to yield net gain because the products are formed too far from the cell to allow quantitatively significant acquisition. Bacteria are surprisingly uniformly distributed in pore water on the millimeter to centimeter scale, with their state of (in)activity being determined by local availability of space and organic matter. Due to differing digestive geometries, bacteria and animals have very different marginal gain functions from secretion of additional enzyme molecules.
 
Day: Thursday, Feb. 4
Time: 09:45 - 10:00am
Location: Hilton of Santa Fe
 
Code: SS30FR0945S