Short-term variations in the abundance and cell volume of bacterioplankton in an artificial tropical lake |
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Authors: | Jugnia Louis B Tadonléké Rémy D Sime-Ngando Télesphore Foto Samuel M Kemka N |
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Institution: | (1) Laboratoire de Biologie Comparée des Protistes, UPRES-A CNRS 6023, Université Blaise-Pascal, 63177 Aubière Cedex, France;(2) Laboratoire de Biologie Générale, Faculté des Sciences, Université de Yaoundé I, B.P. 812, Yaoundé, Cameroun |
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Abstract: | Circadian and spatial fluctuations in bacterioplankton abundance and cell volume were examined, for the first time, in the
Municipal Lake located in the down town area of Yaoundé (Capital of Cameroon, Central Africa, ca 3° 52′ N, 11° 31′ E). Bacterial
cell volumes (range, 0.05 to 0.2 μm3) were consistent with those reported for other aquatic systems while bacterial densities
(0.8 to 2 × 108 cells ml-1) were among the highest values reported in pelagic systems. These variables and chlorophyll a and
dissolved oxygen concentrations within a single depth-zone varied from 13 to 61%, while water temperature fluctuated only
from 2 to 6%. Spatial fluctuations of physical-chemical and biological variables were generally higher during the day-time
than during the night-time. A significant diel variation was provided for bacterial cell volume in the surface waters where
synchronized cell division was occurring during the night. The measured bacterial abundances in this study were 4 to 17 fold
higher than values known from other lakes of similar trophic status, and both cell abundance and volume were not correlated
with chlorophyll. We conclude that this was due to the dependence of bacterial populations to different sources of allochthonous
substrates, including untreated sewage from the major influents of the lake, resuspension of benthic material, and substrate
releasing from macrophytes which are prevalent in the littoral zone of the lake.
This revised version was published online in September 2006 with corrections to the Cover Date. |
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Keywords: | tropical lakes artificial lakes circadian variations plankton bacteria algae |
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