Document Detail

Does microorganism stoichiometry predict microbial food web interactions after a phosphorus pulse?
MedLine Citation:
PMID:  18165873     Owner:  NLM     Status:  MEDLINE    
Knowledge of variations in microbial food web interactions resulting from atmospheric nutrient loads is crucial to improve our understanding of aquatic food web structure in pristine ecosystems. Three experiments mimicking atmospheric inputs at different nitrogen/phosphorus (N/P) ratios were performed in situ covering the seasonal biological succession of the pelagic zone in a high-mountain Spanish lake. In all experiments, abundance, biomass, algal cell biovolume, P-incorporation rates, P-cell quota, and N/P ratio of algae strongly responded to P-enrichment, whereas heterotrophic bacteria remained relatively unchanged. Ciliates were severely restricted when a strong algal exploitation of the available P (bloom growth or storage strategies) led to transient (mid-ice-free experiment) or chronic (late ice-free experiment) P-deficiencies in bacteria. In contrast, maximum development of ciliates was reached when bacteria remained P-rich (N/P < 20) and algae approached Redfield proportions (N/P approximately 16). Evidence of a higher P-incorporation rate supports the proposition that algae and bacteria shifted from a mainly commensalistic-mutualistic to a competitive relationship for the available P when bacterial P-deficiency increased, as reflected by their unbalanced N/P ratio (N/P > 20-24). Hence, the bacterial N/P ratio proved be a key factor to understand the algae-bacteria relationship and microbial food web development. This study not only demonstrates the interdependence of life history strategies, stoichiometric nutrient content, and growth but also supports the use of bacterial N/P thresholds for diagnosing ciliate development, a little-studied aspect worthy of further attention.
Presentación Carrillo; Manuel Villar-Argaiz; Juan M Medina-Sánchez
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-12-29
Journal Detail:
Title:  Microbial ecology     Volume:  56     ISSN:  0095-3628     ISO Abbreviation:  Microb. Ecol.     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-06-30     Completed Date:  2008-09-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7500663     Medline TA:  Microb Ecol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  350-63     Citation Subset:  IM    
Instituto del Agua, Universidad de Granada, 18071, Granada, Spain.
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MeSH Terms
Algae* / growth & development,  metabolism
Bacteria* / growth & development,  metabolism
Ciliophora* / growth & development,  metabolism
Food Chain*
Fresh Water / microbiology,  parasitology
Heterotrophic Processes
Nitrogen / metabolism
Phosphorus / metabolism*
Reg. No./Substance:
7723-14-0/Phosphorus; 7727-37-9/Nitrogen

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