The Composition And Function Of The Main Group Of Microbial Food Loop In Offshore Of Polar Region

Through several Antarctic and Arctic expeditions, including the 21th Chinese National Antarctic Expedition in 2004/2005, and the Chinese Arctic Yellow River Station Expeditions in 2004 and 2005, the following studies were carried out in Great Wall Bay and Ardley Bay near Chinese Great Wall Station, King George Island (Anatarctic), and in Kongsfjorden near Chinese Yellow River Station, Svalbard (Arctic): The biomass, community structure and the vertical distribution within the upper water column, at the same time, the vertical distribution of temperature, salinity, nutrients and chlorophyll a concentration were determined. And the growth and grazing rates of the main plankton assemblages were tested through the dilution experiment. The distribution and biomass of mixotrophic plankton in Kongsfjorden were also investigated.In Great Wall Bay and Ardley Bay, water samples were taken at 0, 2, 5 and 10m depths with a 2.5-L Kemmer water sampler, and profiles of temperature and salinity were obtained using a YSI-560 Water Quality Sonde. 1-2L water samples were filtered onto the GF/F filters for chlorophyll a concentration measurement. 30~100mL subsamples were stained with the fluorochrome DAPI (4',6-diamidino-2- phenylindole) for 10min, and then filtered onto 0.2μm pore size black-stained polycarbonate filters for microbial enumeration with Leica (or Zeiss) epifluorescence microscope. A further 250 mL water sample was preserved in Lugol's Solution (final concentration 1.5%) for diatom enumeration. A series dilution experiments were used to analyze the growth and grazing rates of the main assemblages of microbial food loop.In Kongsfjorden of Arctic, water samples were taken with a 2.5-L Niskin water sampler at seven discrete depths down to 50m, and profiles of temperature, nutrients and salinity were obtained using a SEB-19plus CTD. 500-1000mL water samples were filtered onto the GF/F filters for chlorophyll a concentration measurement. 30~50mL subsamples were stained with the fluorochrome DAPI and filtered onto 0.2μm pore size black-stained polycarbonate filters for <20μm microbial enumeration. 150~250mL subsamples were filtered onto 0.8μm pore size black-stained polycarbonate filters for >20μm microbial individual enumeration. The fluorescent labelled microspheres (FLMs) were used as probe to distinguish mixotrophic plankton...