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AME 24:109-115 (2001)
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Abstract
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Marine bacterioplankton show bursts of rapid growth induced by substrate shifts
Åke Hagström1,*, Jarone Pinhassi2, Ulla Li Zweifel1
1Marine Sciences, Kalmar University, Box 905, 39129 Kalmar, Sweden
2Department of Microbiology, Umeå University, 90187 Umeå, Sweden
*E-mail: ake.hagstrom@hik.se
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ABSTRACT: Diel dynamics of marine bacterioplankton was monitored at sampling sites in the Bothnian Sea (NB1) and the Mediterranean Sea (Villefranche Bay). At both locations, considerable diel variation was found in bacterial production, with highest
values recorded during midday and lower values during night and early morning. The abundance of bacteria scored by the number of nucleoid-containing cells (NUCC) also changed during the day, with minimum numbers during midday. The bacterial turnover rate
based on thymidine incorporation and NUCC varied between 0.22-0.31 and 0.48-2.40 d-1 in the Bothnian Sea and Mediterranean, respectively. There was a significant positive correlation between the community turnover rate and phosphate
concentration both in the Bothnian Sea and in the Mediterranean. In the Mediterranean, nutrient addition experiments showed that phosphate was the least available 'commodity' for the bacterial community. Combined addition of phosphate and glucose
stimulated bacterial growth more than a single addition of either substrate alone, reaching a bacterial turnover of 2.4 d-1. This value was equal to the maximum turnover rate found in situ during the daily cycle. Our results suggest that
bacterioplankton rapidly adjust their growth rate in response to diel changes in nutrient supply.
KEY WORDS: Bacterioplankton · Growth · Substrate
Full text in pdf format
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Published in AME Vol.
24, No. 2
(2001) on May 30
ISSN: 0948-3055.
Copyright © Inter-Research, Oldendorf/Luhe, 2001
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