(H. Ducklow, PI)

Microorganisms < 1 _m long form an important ecosystem component at the base of Antarctic foodwebs and catalyze critical biogeochemical transformations in the carbon, nitrogen and other elemental cycles. The goal of the PAL microbial component is to document the long term trends and variability of bulk bacterial and Archaeal biomass and production rates in space and time. Observations have been made on the LTER sampling grid encompassing the offshore domain since 1993. More recently we initiated a semiweekly time series in the inshore regime near Palmer Station. The goal of the biogeochemistry component is to understand how climate change and ecosystem response impacts several key biogeochemical properties: dissolved oxygen, organic and inorganic carbon. The Southern Ocean is an important sink for atmospheric CO2; our studies of the metabolically active gases are aimed at clarifying the linkages among biological and physical processes affecting CO2 storage. Microbial oxidation of DOC is an important flow in marine ecosystems including the Antarctic and provides a link between microbial functioning and O2/CO2 cycles.