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Diel Division Cycle and Growth Rates of Synechococcus in Lakes Huron and Michigan 1
Author(s) -
Fahnenstiel Gary L.,
Patton Tyrone R.,
Carrick Hunter J.,
McCormick Michael J.
Publication year - 1991
Publication title -
internationale revue der gesamten hydrobiologie und hydrographie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 0020-9309
DOI - 10.1002/iroh.19910760415
Subject(s) - diel vertical migration , growth rate , synechococcus , biology , cell division , annual cycle , division (mathematics) , zoology , morning , clone (java method) , population , cyanobacteria , ecology , botany , biochemistry , bacteria , cell , dna , genetics , geometry , mathematics , arithmetic , demography , sociology
A clone of Synechococcus isolated from Lake Huron and natural populations of Synechococcus from lakes Huron and Michigan were studied in 1989 to examine the diel division cycle and to provide estimates of the in situ growth rate based on the frequency of dividing cells (FDC) method. Cultured populations of Synechococcus exhibited a consistent diel division pattern with a midday/afternoon (1100–1800 h) peak in the percent of dividing cells. The maximum percent of dividing cells varied among cultures (8‐27%) and was related to the growth rate. A small fraction of dividing cells (3‐5%) remained throughout the dark period, suggesting that some cells were arrested in the doublet stage prior to division. The duration of division ( t d ) ranged from 2.6‐4.9 h, with a 3.7 h mean for cultures with growth rates ≥0.34 d −1 but increased to 8 h at a lower growth rate of 0.20 d −1 . The diel division pattern for natural populations was very similar to the laboratory clone; an afternoon peak (1400‐2100 h) in dividing cells and a small fraction of dividing cells (2‐5%) remained during the dark period. The maximum percent of dividing cells for natural populations ranged from 6‐10%. In situ growth rates, determined from the FDC and assuming a constant t d of 3.7 h, ranged from 0.30‐0.42 d −1 . The FDC method may provide accurate estimates of in situ growth, particularly in environments where the growth rate is >0.34 d −1 , but in lakes Huron and Michigan where growth rates can be lower and t d values may increase, FDC‐growth rates must be viewed with caution.