| Summary: | Moored sediment traps intercepted material for approximately one year in the southern Ross Sea, Antarctica. Fecal pellets >100 um in trap samples were classified according to morphology as tabular, ellipsoidal, or cylindrical. The abundance, relatively large size, and high settling velocities of tabular pellets made them the most important pellet type by volume in vertical flux to 250 meters water depth and to the sea floor. Most pellets arrived at the traps in short-lived, high-flux events from the end of January through early March. Numerically, tabular pellets dominated pellet flux to 250 meters, and ellipsoidal pellets dominated pellet flux to the sea floor. This change suggests the presence of an active mid-depth zooplankton community that intercepts and repackages settling material. The different physical properties and settling velocities of the pellet types indicate that changes in pellet producer populations might significantly affect vertical flux and could modify regional biogeochemical cycles.
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