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Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream

Flow regimes are important drivers of both stream community and biogeochemical processes. However, the interplay between community and biogeochemical responses under different flow regimes in streams is less understood. In this study, we investigated the structural and functional responses of periphyton and macroinvertebrates to different densities of the Mediterranean barbel (Barbus meridionalis, Cyprinidae) in two stream reaches differing in flow regime. The study was conducted in Llémena Stream, a small calcareous Mediterranean stream with high nutrient levels. We selected a reach with permanent flow (permanent reach) and another subjected to flow regulation (regulated reach) with periods of flow intermittency. At each reach, we used in situ cages to generate 3 levels of fish density. Cages with 10 barbels were used to simulate high fish density ( > 7 ind m − 2 ); cages with open sides were used as controls (i.e. exposed to actual fish densities of each stream reach) thus having low fish density; and those with no fish were used to simulate the disappearance of fish that occurs with stream drying. Differences in fish density did not cause significant changes in periphyton biomass and macroinvertebrate density. However, phosphate uptake by periphyton was enhanced in treatments lacking fish in the regulated reach with intermittent flow but not in the permanent reach, suggesting that hydrologic alteration hampers the ability of biotic communities to compensate for the absence of fish. This study indicates that fish density can mediate the effects of anthropogenic alterations such as flow intermittence derived from hydrologic regulation on stream benthic communities and associated biogeochemical processes, at least in eutrophic streams

This research was supported by the Spanish Ministry of Economy and Competitiveness (projects CGL2013-43822-R and CGL2016-80820-R); the Government of Catalonia (ref. 2014 SGR 484 and CERCA Programme) and the University of Girona (ref.MPCUdG2016/120). David Almeida benefitted from a postdoctoral fellowship from the Generalitat de Catalunya (2013 BP_B00172) and Baigal-Amar Tuulaikhuu benefited from a doctoral fellowship from the European Commission (Erasmus Mundus Partnership “Techno II”, 372228-1-2012-1-FR-ERA MUNDUS-EMA21)

Elsevier

Manager: Ministerio de Economía y Competitividad (Espanya)
Author: Rubio Gracia, Francesc Manel
Almeida, David
Bonet, Berta
Casals, Frederic
Espinosa Angona, Carmen
Flecker, Alexander S.
García-Berthou, Emili
Martí, Eugènia
Tuulaikhuu, Baigal-Amar
Vila i Gispert, Anna
Zamora Hernández, Lluís
Guasch i Padró, Helena
Abstract: Flow regimes are important drivers of both stream community and biogeochemical processes. However, the interplay between community and biogeochemical responses under different flow regimes in streams is less understood. In this study, we investigated the structural and functional responses of periphyton and macroinvertebrates to different densities of the Mediterranean barbel (Barbus meridionalis, Cyprinidae) in two stream reaches differing in flow regime. The study was conducted in Llémena Stream, a small calcareous Mediterranean stream with high nutrient levels. We selected a reach with permanent flow (permanent reach) and another subjected to flow regulation (regulated reach) with periods of flow intermittency. At each reach, we used in situ cages to generate 3 levels of fish density. Cages with 10 barbels were used to simulate high fish density ( > 7 ind m − 2 ); cages with open sides were used as controls (i.e. exposed to actual fish densities of each stream reach) thus having low fish density; and those with no fish were used to simulate the disappearance of fish that occurs with stream drying. Differences in fish density did not cause significant changes in periphyton biomass and macroinvertebrate density. However, phosphate uptake by periphyton was enhanced in treatments lacking fish in the regulated reach with intermittent flow but not in the permanent reach, suggesting that hydrologic alteration hampers the ability of biotic communities to compensate for the absence of fish. This study indicates that fish density can mediate the effects of anthropogenic alterations such as flow intermittence derived from hydrologic regulation on stream benthic communities and associated biogeochemical processes, at least in eutrophic streams
This research was supported by the Spanish Ministry of Economy and Competitiveness (projects CGL2013-43822-R and CGL2016-80820-R); the Government of Catalonia (ref. 2014 SGR 484 and CERCA Programme) and the University of Girona (ref.MPCUdG2016/120). David Almeida benefitted from a postdoctoral fellowship from the Generalitat de Catalunya (2013 BP_B00172) and Baigal-Amar Tuulaikhuu benefited from a doctoral fellowship from the European Commission (Erasmus Mundus Partnership “Techno II”, 372228-1-2012-1-FR-ERA MUNDUS-EMA21)
Document access: http://hdl.handle.net/2072/299798
Language: eng
Publisher: Elsevier
Rights: Tots els drets reservats
Subject: Ciprínids
Cyprinidae
Peixos -- Alimentació
Fishes -- Feeding and feeds
Peixos -- Poblacions
Fish populations
Title: Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream
Type: info:eu-repo/semantics/article
Repository: Recercat

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