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Microbial carbon processing along a river discontinuum

The hydrological continuum in rivers can be altered by the presence of small dams that modify the water residence time (WRT) and prevailing habitat, turning lotic river sections into lentic ones and influencing downstream reaches. The structure and activity of the microbial community occurring in the benthic and planktonic compartments can be modified by these small dams. We studied the microbial community processing of organic C along a sequence of 4 lentic-lotic sections in a medium-size Mediterranean river during base flow (spring) and low flow (summer). We hypothesized that longitudinal anomalies in WRT would influence the relative contribution of benthic vs planktonic compartments and their relevance in C processing along the river network, particularly during low flows. The biomass of free-living and particle-associated bacterioplankton was higher in the lentic sections, which had longer WRT, resulting in higher organic C processing (enzymatic activities and respiration). Microbial aggregates occurred in the lentic sections especially during the low-flow period and resulted in hotspots of organic C processing. The lotic reaches received a significant contribution of C in the form of bacterio- and phytoplankton. The small dams subsidized the lotic sections downstream and increased their respiration activity. Our results reveal the influence of small dams on organic C processing along the river network. Accounting for their effect, together with that of large dams, may be essential for accurate estimations of organicmatter transformation in river networks

This study was funded by the projects of the Spanish Ministry of Economy and Competitiveness CARBONET (CGL2011-30474-C02-01) and FUNSTREAM (CGL2014-58760-C3-3-R)

Society for Freshwater Science

Manager: Ministerio de Ciencia e Innovación (Espanya)
Ministerio de Economía y Competitividad (Espanya)
Author: Proia, Lorenzo
von Schiller, Daniel
Gutiérrez, Carmen
Casas Ruiz, Joan Pere
Gómez-Gener, Lluís
Marcé Romero, Rafael
Obrador, Biel
Acuña i Salazar, Vicenç
Sabater, Sergi
Abstract: The hydrological continuum in rivers can be altered by the presence of small dams that modify the water residence time (WRT) and prevailing habitat, turning lotic river sections into lentic ones and influencing downstream reaches. The structure and activity of the microbial community occurring in the benthic and planktonic compartments can be modified by these small dams. We studied the microbial community processing of organic C along a sequence of 4 lentic-lotic sections in a medium-size Mediterranean river during base flow (spring) and low flow (summer). We hypothesized that longitudinal anomalies in WRT would influence the relative contribution of benthic vs planktonic compartments and their relevance in C processing along the river network, particularly during low flows. The biomass of free-living and particle-associated bacterioplankton was higher in the lentic sections, which had longer WRT, resulting in higher organic C processing (enzymatic activities and respiration). Microbial aggregates occurred in the lentic sections especially during the low-flow period and resulted in hotspots of organic C processing. The lotic reaches received a significant contribution of C in the form of bacterio- and phytoplankton. The small dams subsidized the lotic sections downstream and increased their respiration activity. Our results reveal the influence of small dams on organic C processing along the river network. Accounting for their effect, together with that of large dams, may be essential for accurate estimations of organicmatter transformation in river networks
This study was funded by the projects of the Spanish Ministry of Economy and Competitiveness CARBONET (CGL2011-30474-C02-01) and FUNSTREAM (CGL2014-58760-C3-3-R)
Document access: http://hdl.handle.net/2072/299525
Language: eng
Publisher: Society for Freshwater Science
Rights: Tots els drets reservats
Subject: Ecologia microbiana
Microbial ecology
Title: Microbial carbon processing along a river discontinuum
Type: info:eu-repo/semantics/article
Repository: Recercat

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