Active bacteria (CTC+) in temperate lakes: temporal and cross-system variations
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Active bacteria (CTC+) in temperate lakes: temporal and cross-system variations. / Søndergaard, Morten; Danielsen, M.
I: Journal of Plankton Research, Bind 23, Nr. 11, 2001, s. 1195-1206.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Active bacteria (CTC+) in temperate lakes: temporal and cross-system variations
AU - Søndergaard, Morten
AU - Danielsen, M.
PY - 2001
Y1 - 2001
N2 - The temporal variation in the abundance and proportion of highly respiration-active bacteria in the eutrophic lakes Esrum and Frederiksborg Slotssø was determined with the redox dye 5-cyano-2,3-ditolyl tetrazolium chloride (CTC). In addition, a comparative late summer study was undertaken across a gradient of nutrient enrichment in Danish lakes. The purpose was to investigate the importance of substrate (chlorophyll) and temperature for the control of CTC-active cells (CTC+). The abundance of CTC+ cells was much lower and more variable than the total number of cells counted after 4',6-diamidino-2-phenylindole (DAPI) staining. The proportion of CTC+ cells in Lake Esrum and Frederiksborg Slotssø was normally <5%, and between 2.5 and 20% in 14 other lakes. The abundance as well as the proportion of CTC+ cells increased with chlorophyll in Lake Esrum and Frederiksborg Slotssø, and chlorophyll explained 43% of the variability in CTC+ abundance. In the comparative study, the abundance of CTC+ cells increased along the chlorophyll gradient, which explained 49% of the variability. The results showed that the abundance and, to a lesser degree, the proportion of CTC+ bacteria were controlled by substrate supply. One consequence of the low abundance of active bacteria is that in situ growth rates scaled to CTC+ cells are 3- to 7-fold higher than those scaled to DAPI counts. It is suggested that studies on factors controlling bacterioplankton activity at the single-cell level should be investigated scaled to active cells.
AB - The temporal variation in the abundance and proportion of highly respiration-active bacteria in the eutrophic lakes Esrum and Frederiksborg Slotssø was determined with the redox dye 5-cyano-2,3-ditolyl tetrazolium chloride (CTC). In addition, a comparative late summer study was undertaken across a gradient of nutrient enrichment in Danish lakes. The purpose was to investigate the importance of substrate (chlorophyll) and temperature for the control of CTC-active cells (CTC+). The abundance of CTC+ cells was much lower and more variable than the total number of cells counted after 4',6-diamidino-2-phenylindole (DAPI) staining. The proportion of CTC+ cells in Lake Esrum and Frederiksborg Slotssø was normally <5%, and between 2.5 and 20% in 14 other lakes. The abundance as well as the proportion of CTC+ cells increased with chlorophyll in Lake Esrum and Frederiksborg Slotssø, and chlorophyll explained 43% of the variability in CTC+ abundance. In the comparative study, the abundance of CTC+ cells increased along the chlorophyll gradient, which explained 49% of the variability. The results showed that the abundance and, to a lesser degree, the proportion of CTC+ bacteria were controlled by substrate supply. One consequence of the low abundance of active bacteria is that in situ growth rates scaled to CTC+ cells are 3- to 7-fold higher than those scaled to DAPI counts. It is suggested that studies on factors controlling bacterioplankton activity at the single-cell level should be investigated scaled to active cells.
M3 - Journal article
VL - 23
SP - 1195
EP - 1206
JO - Journal of Plankton Research
JF - Journal of Plankton Research
SN - 0142-7873
IS - 11
ER -
ID: 144621