Abstract | River and stream biofilms in mediterranean
fluvial ecosystems face both extreme seasonality
as well as arrhythmic fluctuations. The hydrological
extremes (droughts and floods) impose direct changes
in water availability but also in the quantity and quality
of organic matter and nutrients that sustain the
microbial growth. This review analyzes how these
ecological pulses might determine unique properties
of biofilms developing in mediterranean streams. The
paper brings together data from heterotrophic and
autotrophic community structure, and extracellular
enzyme activities in biofilms in mediterranean
streams. Mediterranean stream biofilms show higher
use of peptides during the favorable period for epilithic
algae development (spring), and preferential use of
cellulose and hemicellulose in autumn as a response to
allochthonous input. The drying process causes the
reduction in bacterial production and chlorophyll
biomass, but the rapid recovery of both autotrophs
and heterotrophs with rewetting indicates their adaptability
to fluctuations. Bacteria surviving the drought
are mainly associated with sediment and leaf litter
which serve as ''humid refuges''. Some algae and
cyanobacteria show resistant strategies to cope with
the drought stress. The resistance to these fluctuations
is strongly linked to the streambed characteristics
(e.g., sediment grain size, organic matter accumulation,
nutrient content). |
Text | 223596 2012 10.1007/s10750 012 1302 y Biofil Extracellular enzymes Drought resistance Bacteria Microbial biofilm structure and organic matter use in Mediterranean streams Romani A.M., Amalfitano S., Artigas J., Fazi S., Sabater S., Timoner X.,Ylla I., Zoppini A. A. M. Roman ´ S. Sabate X. Timoner I. Ylla Institute of Aquatic Ecology, University of Girona, Campus de Montilivi, 17071 Girona, Spain e mail anna.romani@udg.edu S. Amalfitano S. Fazi A. Zoppini Water Research Institute IRSA , National Research Council CNR , Via Salaria km 29.3 CP10, 00015 Monterotondo, Italy J. Artigas Irstea, 3 Quai Chauveau CP 220, 69336 Lyon, France S. Sabater X. Timoner Catalan Institute for Water Research ICRA , Emili Grahit 101, Edifici H2O Parc Cient ´fic i Tecnolo`gic de la Universitat de Girona, 17003 Girona, Spain River and stream biofilms in mediterranean fluvial ecosystems face both extreme seasonality as well as arrhythmic fluctuations. The hydrological extremes droughts and floods impose direct changes in water availability but also in the quantity and quality of organic matter and nutrients that sustain the microbial growth. This review analyzes how these ecological pulses might determine unique properties of biofilms developing in mediterranean streams. The paper brings together data from heterotrophic and autotrophic community structure, and extracellular enzyme activities in biofilms in mediterranean streams. Mediterranean stream biofilms show higher use of peptides during the favorable period for epilithic algae development spring , and preferential use of cellulose and hemicellulose in autumn as a response to allochthonous input. The drying process causes the reduction in bacterial production and chlorophyll biomass, but the rapid recovery of both autotrophs and heterotrophs with rewetting indicates their adaptability to fluctuations. Bacteria surviving the drought are mainly associated with sediment and leaf litter which serve as humid refuges . Some algae and cyanobacteria show resistant strategies to cope with the drought stress. The resistance to these fluctuations is strongly linked to the streambed characteristics e.g., sediment grain size, organic matter accumulation, nutrient content . Articolo on line Articolo.pdf Articolo in rivista Kluwer 1573 5117 Hydrobiologia Dordr., Online Hydrobiologia Dordr., Online Hydrobiologia Dordr., Online Hydrobiologia. Dordr., Online Hydrobiologia Dordrecht Dordr., Online Hydrobiologia Boston Dordr., Online Hydrobiologia London Dordr., Online stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO annamaria.zoppini ZOPPINI ANNAMARIA TA.P04.032.002 Ruolo delle comunita microbiche nei cicli biogeochimici e nella degradazione degli inquinanti |