Microbial activities in the Lena River delta and Laptev Sea

Total bacteria, bacterial production and bacterial extracellular enzymatic activities were determined from water samples taken in the Lena River delta and adjacent Laptev Sea. These parameters were determined to assess organic matter recycling and ultimate preservation with regard to organic carbon production, transport from continent into the ocean, and sequestration in arctic environments. Total bacterial cells varied in the range 2.0 × 108 − 8.3 × 109 1−1, higher values being encountered in the Lena River and its delta and in the Laptev Sea, at stations influenced by riverine waters. Net bacterial production was highly variable, from high values in the Lena River and its delta (up to 7.8 pmol l−1 h−1) down to the lowest values (< 0.005 pmol l−1 h−1) observed in open-sea, high-salinity waters (> 19). Specific extracellular enzymatic activities of protease, glucosidase, galactosidase and phosphatase were determined with some insight into kinetic parameters, substrate affinity and maximum incorporation rate.