Phagotrophy and fecal pellet production by an athecate dinoflagellate in antarctic sea ice
Buck, K.R.; Bolt, P.A.; Garrison, D.L.
Marine Ecology Progress Series 60(1-2): 75-84
A phagotrophic athecate dinoflagellate was found in sea ice and the underlying water-column of the Weddell Sea ice edge during the austral autumn of 1986. This organism lacked a sulcus, a cingulum and flagella but possessed a dinokont nucleus, a cystostome and amphiesmal vesicles. Abundances exceeded 105 l-1 in the ice. The single large food vacuole contained a variety of protistan prey but was predominantly composed of the pennate diatom Nitzschia cylindrus. The fecal pellet produced upon the egestion of this vacuole was membrane bound. Of the fecal pellet volume 15% was identifiable protoplasm, mostly N. cylindrus. Carbon per pellet averaged 97 pg, and abundance of the fecal pellet in the ice also exceeded 105 l-1. Release of the fecal pellet into the underlying water column upon melting of the ice may account for a significant proportion of the particulate organic carbon available to metazoan grazers at the ice edge. Flux of material out of the euphotic zone via this fecal pellet may be significant.