39 research outputs found
Linkages between bacterioplankton community composition, heterotrophic carbon cycling and environmental conditions in a highly dynamic coastal ecosystem
12 páginas, 4 figuras, 1 tablasWe used mesocosm experiments to study the bacterioplankton
community in a highly dynamic coastal
ecosystem during four contrasting periods of the
seasonal cycle: winter mixing, spring phytoplankton
bloom, summer stratification and autumn upwelling.
A correlation approach was used in order to measure
the degree of coupling between the dynamics of
major bacterial groups, heterotrophic carbon cycling
and environmental factors. We used catalysed
reporter deposition-fluorescence in situ hybridization
to follow changes in the relative abundance of
the most abundant groups of bacteria (Alphaproteobacteria,
Gammaproteobacteria and Bacteroidetes).
Bacterial carbon flux-related variables included bacterial
standing stock, bacterial production and microbial
respiration. The environmental factors included
both, biotic variables such as chlorophyll-a concentration,
primary production, phytoplankton extracellular
release, and abiotic variables such as the
concentration of dissolved inorganic and organic
nutrients. Rapid shifts in the dominant bacterial
groups occurred associated to environmental
changes and bacterial bulk functions. An alternation
between Alphaproteobacteria and Bacteroidetes was
observed associated to different phytoplankton growth phases. The dominance of the group
Bacteroidetes was related to high bacterial biomass
and production. We found a significant, nonspurious,
linkage between the relative abundances
of major bacterial groups and bacterial carbon
cycling. Our results suggest that bacteria belonging
to these major groups could actually share a function
in planktonic ecosystemsThis research was supported by the MEC contract
IMPRESION (VEM2003-20021). E.T. was funded by a European
Community Marie Curie Reintegration Fellowship
(MERG-CT-2004-511937) and a Juan de la Cierva-MEC
contractPeer reviewe