Phytoplankton equilibrium phases during thermal stratification in a deep subtropical reservoir

1. Equilibrium and non-equilibrium hypotheses have often been used to explain observations in community ecology. Published case studies have demonstrated that steady state phytoplankton assemblages are more likely to occur in deep lakes than in shallow mixed ones. 2. Phytoplankton seasonal successio...

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Published in:Freshwater biology 2008-05, Vol.53 (5), p.952-963
Main Authors: BECKER, VANESSA, HUSZAR, VERA LÚCIA M, NASELLI-FLORES, LUIGI, PADISÁK, JUDIT
Format: Article
Language:English
Subjects:
Anabaena
Animal and plant ecology
Animal, plant and microbial ecology
Asterionella
Biological and medical sciences
Brazil
equilibrium phase
Fresh water ecosystems
Fundamental and applied biological sciences. Psychology
monomictic reservoir
Nephrocytium
steady state
Synecology
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Summary:1. Equilibrium and non-equilibrium hypotheses have often been used to explain observations in community ecology. Published case studies have demonstrated that steady state phytoplankton assemblages are more likely to occur in deep lakes than in shallow mixed ones. 2. Phytoplankton seasonal succession was studied by weekly sampling in Faxinal Reservoir (S Brazil), a subtropical deep, clear, warm monomictic and slightly eutrophic reservoir. This study demonstrated an alternation of steady and non-steady state phases of phytoplankton assemblages with different dominant species during the steady states. 3. During the studied period, three steady states were identified with different dominant algal species: Anabaena crassa (Cyanobacteria), Nephrocytium sp. (green algae) and Asterionella (diatoms). 4. Each steady state in Faxinal Reservoir developed under stratified conditions of the water column according to the predictions of the disturbance concepts. Apparently, the major forces driving the development and persistence of these steady-state phases were closely related to thermal stratification and its consequences. 5. This study is the first report on development of more than one steady state within a year in a stratified water body. The development of three steady states might be the result of the relatively long stratification period in the Faxinal Reservoir and to its unique geochemical features.
ISSN:0046-5070
1365-2427
DOI:10.1111/j.1365-2427.2008.01957.x