Aquatic Sciences Meeting, Albuquerque 2001

CS20 Microbial Dynamics

Date: Friday, February 16, 2001, Time: 8:45:00 AM

Location: Ruidoso/Pecos

Bertilsson, S, , Massachusetts Institute of Technology, Cambridge, USA, Stebe@mit.edu

Hansson, L, A, Lund University, Lund, Sweden, Lars-Anders.Hansson@limnol.lu.se

Graneli, W, , Lund University, Lund, Sweden, wilhelm.graneli@limnol.lu.se

BACTERIAL GROWTH AND ABUNDANCE IN ARCTIC FRESHWATERS -SUBSTRATE AND GRAZING CONTROL

The Arctic Ocean receives a major input of dissolved organic matter from the northern Tundra. This input is influenced by heterotrophic bacterial activity in freshwaters linking soil systems to the marine environment. Bacterial degradation of organic matter also forms an important link of energy and nutrients to higher trophic levels with a strong influence on food webs. We studied the potential influence of growth substrate-availability and zooplankton grazing on bacterial abundance and activity in a wide range of freshwaters in the Canadian Arctic. The bacterial growth and abundance was measured in 26 lakes and ponds on islands in between Alaska and northern Greenland. These in situ parameters were positively correlated to the bacterial regrowth in dilution cultures prepared from these systems, indicating a major role of substrate availability in the regulation of bacterial abundance and activity in these systems. Grazer control is an alternative mechanism that could potentially influence bacterial activity and abundance and we show that the dense populations of Daphnia that are frequently observed in arctic freshwaters have the potential to graze efficiently on bacteria.

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Aquatic Sciences Meeting, Albuquerque 2001

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