The PAL study area encompasses a 200 x 500 km region extending from the nearshore coastal zone heavily influenced by seasonal sea ice cover to the open Southern Ocean, and from a northern area where sea ice cover is now limited to only the colder winters, to the south where perennial sea ice cover persists into summer months. In this region, primary production is dominated by unicellular phytoplankton and limited by light availability to the October-April period. The region is characterized by spring phytoplankton blooms that have declined by up to 90% in the northern region since 1978. In the south, blooms have increased by 60%. In both regions, these differential changes are due to declining sea ice cover that has reduced vertical stratification in the north, but opened new areas to light penetration in the south. Heterotrophic prokaryotes (bacteria and some archaea) process up to 20% of the primary production over the annual cycle. This fraction is about half that metabolized in lower latitude oceans, but low temperature alone is not the major control on bacterial activity. Rather, differences in foodweb structure and dynamics limit the amount of dissolved organic matter channeled to bacteria. In this region, alpha- and gamma proteobacteria and the Sphingobacter-Flavobacter group together comprise about 70% of the total bacterial assemblage. Contact: Hugh Ducklow, hducklow@mbl.edu. Research for this poster was supported by NSF LTER Awards OPP 0217282 and 0823101.