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BASICS Résumé de rapport

Project ID: EVK3-CT-2002-00078
Financé au titre de: FP5-EESD
Pays: France

Changes of bacterial community composition in the Bay of Villefranche (NW Mediterranean Sea)

The diversity of Bacteria and Archaea was investigated during a 1.5 years study in the Bay of Villefranche and sequence information is available for the phylogenetic affiliation of the detected phylotypes. Between 17 and 30 bands (phylotypes) were detected. Using cluster analysis, phylotypes grouped into specific periods such as phytoplankton bloom, Synechococcus bloom, summer and fall/winter.

However, this grouping differed for waters above and below the thermocline. Specific phylotypes responded characteristically to short-term changes such as blooms, local upwellings, heavy rainfall, forest fires and Sahara dust depositions. These results indicate that unpredictable short-term events play a significant and previously not sufficiently considered role for sustaining diversity in coastal microbial food webs.

Diversity was not linked to ecosystem functions using conventional analysis such as multiple regression analysis, however, when artificial neural networks were used, bacterial production and respiration were linked strongly but in a non-linearizable way to bacterial diversity. This suggests a complex pattern between diversity and ecosystem function, which has to be considered in assessing the effects of global change.

Informations connexes

Reported by

Station Zoologique
06234 Villefranche-sur-mer