Title | DYNAMICS OF BENTHIC BACTERIAL COMMUNITY IN A RIVERINE ENVIRONMENT SUBJECT TO HYDROLOGICAL FLUCTUATIONS (RIVER MULARGIA, ITALY) |
Abstract | Temporary rivers are characterized by
recurrent dry phases, and global warming will stress
their hydrology by amplifying extreme events. Microbial
degradation and transformation of organic matter
(OM) in riverbed sediment are key processes with
regard to carbon and nutrient fluxes. In this study, we
describe structural and functional changes of benthic
microbial communities in a riverine environment subject
to hydrological fluctuation. Sampling was carried
out in the outlet section of the Mulargia River (Sardinia,
Italy) under various water regimes, including one flood
event. Overall, sediments were characterized by low
bacterial cell abundance (range 0.6-1.8 9 109 cell g-1)
as a consequence of their low nutrient and OM
concentrations. No major differences were found in
the community composition. Alpha-Proteobacteria
dominated during the whole year (range 21-30%)
followed by Beta-Proteobacteria, Gamma-Proteobacteria,
and Cytophaga-Flavobacteria which always
contributed \18%. Planctomycetes and Firmicutes
were found in smaller amounts (\7%). In spring, when
the highest total organic carbon content was also
detected (0.42% w/w), both bacterial abundance and C
production (BCP, 170 nmol C h-1 g-1) reached relatively
high values.During the flood event, an increase in
BCP and the highest values of community respiration
(CR, 74 nmol C h-1 g-1) were observed. Moreover,
most of the extracellular enzyme activities (EEA)
changed significantly during the flood. The variation
of the water flowitself can explain part of these changes
and other factors also come into play. The presence of
different patterns of functional parameters could suggest
that the quality of the OM could be the major driving
force in nutrient flux. |
Source | Hydrobiologia (The Hague. Print) 657, pp. 37–51 |
Journal | Hydrobiologia (The Hague. Print) |
Editor | Kluwer Academic Publishers, Boston, Paesi Bassi |
Year | 2010 |
Type | Articolo in rivista |
Authors | ZOPPINI A., AMALFITANO S., FAZI S., PUDDU A. |
Text | 42396 2010 DYNAMICS OF BENTHIC BACTERIAL COMMUNITY IN A RIVERINE ENVIRONMENT SUBJECT TO HYDROLOGICAL FLUCTUATIONS RIVER MULARGIA, ITALY ZOPPINI A., AMALFITANO S., FAZI S., PUDDU A. Water Research Institute IRSA CNR , Via Salaria Km 29.300, CP 10, 00015 Monterotondo, Rome, Italy Temporary rivers are characterized by recurrent dry phases, and global warming will stress their hydrology by amplifying extreme events. Microbial degradation and transformation of organic matter OM in riverbed sediment are key processes with regard to carbon and nutrient fluxes. In this study, we describe structural and functional changes of benthic microbial communities in a riverine environment subject to hydrological fluctuation. Sampling was carried out in the outlet section of the Mulargia River Sardinia, Italy under various water regimes, including one flood event. Overall, sediments were characterized by low bacterial cell abundance range 0.6 1.8 9 109 cell g 1 as a consequence of their low nutrient and OM concentrations. No major differences were found in the community composition. Alpha Proteobacteria dominated during the whole year range 21 30% followed by Beta Proteobacteria, Gamma Proteobacteria, and Cytophaga Flavobacteria which always contributed \18%. Planctomycetes and Firmicutes were found in smaller amounts \7% . In spring, when the highest total organic carbon content was also detected 0.42% w/w , both bacterial abundance and C production BCP, 170 nmol C h 1 g 1 reached relatively high values.During the flood event, an increase in BCP and the highest values of community respiration CR, 74 nmol C h 1 g 1 were observed. Moreover, most of the extracellular enzyme activities EEA changed significantly during the flood. The variation of the water flowitself can explain part of these changes and other factors also come into play. The presence of different patterns of functional parameters could suggest that the quality of the OM could be the major driving force in nutrient flux. 657 Zoppini et al 2010 Zoppini_Hydrobiologia_2010.pdf Articolo in rivista Kluwer Academic Publishers 0018 8158 Hydrobiologia The Hague. Print Hydrobiologia The Hague. Print Hydrobiologia The Hague. Print Hydrobiologia. The Hague. Print Hydrobiologia Dordrecht The Hague. Print Hydrobiologia Boston The Hague. Print Hydrobiologia London The Hague. Print stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO alberto.puddu PUDDU ALBERTO annamaria.zoppini ZOPPINI ANNAMARIA TA.P02.002.003 Ruolo di comunita microbiche nella degradazione della sostanza organica e nella circolazione del carbonio nei sistemi acquatici |