Spatio-temporal patterns in the abundance of bacterioplankton from Antarctic and SW Atlantic waters

. ALDER, V.A.; FRANZOSI, C.

Portland USA

Congreso; XXXII SCAR and Open Science Conference & COMNAP XXIV AGM; 2012

SCAR

We present an overview of the quantitative distribution of subsurface bacterioplankton abundance and biomass from a data series obtained during summer and autumn of four consecutive years (2002-2005) by latitudinal transects covering Argentine shelf waters, the Drake Passage, the Bellingshausen Sea and the Weddell Sea. Samples collected at each of ca. 300 oceanographic stations were processed (DAPI staining) by duplicate on board. Concentrations of heterotrophic bacteria and other picoplanktonic autotrophic cells (cyanobacteria and picoeukaryotic algae) were estimated by fluorescence microscopy and further analyzed by digital imaging for biovolume-to-biomass conversions. The large spatial scale covered by this study allowed to: 1) examine the seasonal, interannual and spatial fluctuations of bacterioplankton biomass in relation with the main environmental variables (temperature, salinity, Chl-a, nutrients) of these contrasting systems; 2) describe the changes in the heterotrophic/autotrophic ratio from a mesotrophic shelf system to oligotrophic oceanic waters; 3) demonstrate how global temperature increments can affect the ecological trends of bacterioplankton; and 4) relate the different categories of El Niño events to bacterioplankton concentration at local and regional scales. Future plans related with long term data collection from microbial planktonic communities will be briefly discussed.