Urban-Rich, J. L. LUMCON, jurban@lumcon.edu
Landry, M. L. University of Hawaii at Manoa, landry@iniki.soest.hawaii.edu
Peterson, J. O. LUMCON, peterson@lumcon.edu
Dagg, M. J. LUMCON, dagg@lumcon.edu

 
COPEPOD GRAZING ON PROTOZOANS AND PHYTOPLANKTON DURING THE SUMMER IN THE SOUTHERN OCEAN POLAR FRONT REGION: IMPLICATIONS FOR VERTICAL FLUX
 
Copepod grazing on phytoplankton and protozoan standing stocks in the polar front region was investigated in February-March 1998 during the U.S. JGOFS: AESOPS Process II cruise aboard R.V. Rodger Revelle. The amount and type of food ingested will be compared to the measured total organic carbon and biogenic silica content of the egested fecal pellets to estimate the amount of organic carbon assimilated and the relative role of organic carbon and biogenic silica available for export. The total potential fecal pellet organic carbon and biogenic silica export will be calculated from fecal pellet production rates and fecal pellet content. A regional comparison of 3 stations: 1 north, 1 south and one at the polar front suggest that the relative role of carbon to biogenic silica available for export via copepod fecal pellets was dependent upon the diet of the large copepods. South of the polar front (70 degrees S, 165 degrees W), the copepods consumed 9-13% of the daily phytoplankton growth. The dominant large copepods that comprised 75% of the biomass were Calanus propinquus, Calanoides acutus, Metridia longa. From feeding selectivity experiments it was seen that these copepods were consuming primarily large centric and pennate diatoms and a few small nanoflagellates. While at the polar front (60 degrees S, 170 degrees W), the copepod community consumed 10-16% of the daily phytoplankton growth and the dominant large copepod Calanus simillimus fed primarily on ciliates and dinoflagellates. These changes in diet will be reflected in the composition of the potential copepod fecal pellet export.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: SS31WE1335S