Brown, S. L. University of Hawaii,
Landry, M. L. University of Hawaii,
Nunnery, S. University of Hawaii,
Casciotti, K. UCSD,

As part of the US JGOFS Southern Ocean Program, we participated in Spring (October-November) and Summer (January-February) Survey Cruises designed to locate and map the physical and chemical characteristics of the Antarctic Polar Front Zone (APFZ). Our goal was to determine temporal and spatial changes in the microbial community across the frontal region through high resolution sampling for flow cytometric analysis and video microscopy. The Spring Survey Cruise showed a greater abundance of smaller phytoplankton cells north of the front, with a shift to the dominance of larger cells south of the front. This change in the microbial community was even more pronounced later during the Summer Survey cruise, when there was a dramatic minima in phytoplankton cell abundance in the frontal zone as compared to either the north or the south. Heterotrophic bacteria followed a similar trend, showing a marked decrease in cell number in the region of the Polar Front. In contrast, bacterial cell size increased from north to south with a slight minimum in the frontal region. These changes in microbial community size structure and abundance reflect local variations in physical forcing and have important implications for the export fluxes of biogenic materials from the euphotic zone.
Day: Friday, Feb. 5
Time: 02:15 - 02:30pm
Location: Sweeney Center
Code: SS31FR0215S