Microbial Investigations of Surface Microlayers, Water Column, Ice and Sediment in the Arctic Ocean*

A microbiological study was conducted in the area north and northeast of Svalbard, Arctic Ocean. Samples were taken in surface microlayers, ice, water column (down to 300 m) and sediment (maximum depth 3920 m). ATP-content in the upper 100 m was between 8 and 80 ng I-'; total bacterial numbers varied between 0.4 and 4.4 105 ml-l. Ice-samples contained high amounts of ATP (max. 120 ng I-'). Bacteria accumulated at the air-sea interface (surface microlayers) at concentrations 130 to 300 times those in subsurface water Viable counts in the sediment ranged between 100 and 3 . 105 cm-3. The degradation potential of 716 bacterial isolates was measured with 6 different media. A capacity index, c,, measuring the capacity of a group of isolates to degrade certain substrates was determined for the various strata. Bacterial sulfate reduction was measurable in the sediment at the 3 shallowest stations. The data are discussed and compared to those obtained in other marine environments.