Passow, U. D.. Marine Science Institute, University of California Santa Barbara, passow@lifesci.ucsb,edu
Alldredge, A. D.. Marine Science Institute, University of California Santa Barbara, alldredg@lifesci.ucsb.edu

 
GRAZING OF EUPHAUSIDS ON TRANSPARENT EXOPOLYMER PARTICLES
 
Transparent Exopolymer Particles, called TEP, are discrete gel-like particles between 5 and several hundred micrometer in size, which exist as individual particles or become attached to other marine particles. TEP form abiotically by aggregation or gelation from dissolved extracellular polysaccharides. The hypothesis that TEP will clog feeding structures of the common euphausid Euphausia pacifica and thus depress feeding on diatoms was tested. Contrary to the hypothesis grazing was not inhibited by TEP. Instead E. pacifica fed on TEP-clusters, which had formed from TEP, nanoplankton and detrital particles which individually were too small for E. pacifica's filtering apparatus to retain. TEP-clusters were of similar size and food quality as cells and were grazed at rates similar to those of cells. As TEP are formed abiotically from dissolved material, the grazing on TEP by macrozooplankton represents a new pathway in the food web. The aggregation of small, otherwise inaccessible particles into edible TEP-clusters by TEP increased the available food supply further. TEP were newly generated during feeding experiments, presumably due to sloppy feeding of E. pacifica on cells. Given the above results, sloppy feeding will be advantageous for suspension feeders, as the TEP generated increases the food supply both directly and indirectly.
 
Day: Monday, Feb. 1
Time: 03:30 - 03:45pm
Location: Sweeney Center
 
Code: SS17MO0330S