PHOTOSYNTHETIC EFFICIENCY OF PHYTOPLANKTON IN A TROPICAL MOUNTAIN LAKE

Minimum (F0), maximum (Fm), and variable (Fv = Fm - F0) fluorescence andphotosynthetic efficiency (Fv/Fm) of phytoplankton were measured for severaldepths and under laboratory conditions during two seasons (June and October of2000) in Lake Guatavita, Colombia. When the lake was stratified (June) the...

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Bibliographic Details
Published in:Caldasia 2006-06, Vol.28 (1), p.57-66
Main Authors: Pinilla-A, Gabriel A, JOHN CH DONATO-R, Rivera-R, Carlos A
Format: Article
Language:eng ; por
Subjects:
BIOLOGY
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Summary:Minimum (F0), maximum (Fm), and variable (Fv = Fm - F0) fluorescence andphotosynthetic efficiency (Fv/Fm) of phytoplankton were measured for severaldepths and under laboratory conditions during two seasons (June and October of2000) in Lake Guatavita, Colombia. When the lake was stratified (June) the surfacealgae were photoinhibited and photosynthetic efficiency was very low, especially inthe hypolimnion. In October, when the lake was circulating, efficiency was higherthroughout the water column. Laboratory samples exhibited a gradual decline inefficiency over time, but with higher values in October. Significant differencesbetween June and October samples were observed both in the laboratory and thefield. Except for hypolimnetic samples for June, there were no significant differencesbetween field observations and laboratory measures. When the lake was stratified,the concentration of chlorophyll-a was high in the hypolimnion, but the efficiencywas low. During circulation, the concentration of chlorophyll-a was low but theefficiency was higher. The results demonstrate that the photosynthetic efficiencyof the phytoplankton is independent of biomass and that in addition to biomass,other factors, such as availability of nutrients and light could affect photosyntheticefficiency.
ISSN:0366-5232
2357-3759