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

Este artículo contiene 9 páginas, 6 figuras, 3 tablas.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 streamwith high nutrient levels.Weselected a reachwith permanent flow(permanent reach) and another subjected to flowregulation (regulated reach)with periods of flowintermittency. 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 (N7 indm−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 reachwith 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 canmediate the effects of anthropogenic alterations such as flowintermittence 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).Peer reviewe

Inter-population variability in dietary traits of invasive bleak Alburnus alburnus (Actinopterygii, Cyprinidae) across the Iberian Peninsula

The bleak Alburnus alburnus is native to most of Europe. This cyprinid fish is a successful invader in the Iberian Peninsula. No studies exist on its foraging strategies on a large scale for this ecoregion. The aim of the present study was to compare dietary traits of invasive bleak among the main Iberian rivers and a "reference" native bleak population from France. Bleak were sampled during May-June 2019 from the Iberian Rivers Ebro, Tagus, Guadiana, Segura and Guadalquivir and the River Saône (France). Diptera larvae and zooplankton were common food categories in the River Saône. Insect nymphs were more important in the River Ebro. The intake of plant material was higher in the River Tagus. Flying insects were more consumed in the River Guadiana. Nektonic insects were important in the River Guadalquivir. Detritus was a frequent food category for all populations, in terms of occurrence and mass. Dietary parameters followed a unimodal response in relation to the latitudinal gradient, with the maximum values for the Tagus and Guadiana populations. Overall, results suggest that this wide interpopulation variability will contribute to the species¿ successful establishment throughout Mediterranean Europe, which poses a serious risk to its highly valuable native fish fauna

Inter-population variability in dietary traits of invasive bleak Alburnus alburnus (Actinopterygii, Cyprinidae) across the Iberian Peninsula

The bleak Alburnus alburnus is native to most of Europe. This cyprinid fish is a successful invader in the Iberian Peninsula. No studies exist on its foraging strategies on a large scale for this ecoregion. The aim of the present study was to compare dietary traits of invasive bleak among the main Iberian rivers and a "reference" native bleak population from France. Bleak were sampled during May-June 2019 from the Iberian Rivers Ebro, Tagus, Guadiana, Segura and Guadalquivir and the River Saône (France). Diptera larvae and zooplankton were common food categories in the River Saône. Insect nymphs were more important in the River Ebro. The intake of plant material was higher in the River Tagus. Flying insects were more consumed in the River Guadiana. Nektonic insects were important in the River Guadalquivir. Detritus was a frequent food category for all populations, in terms of occurrence and mass. Dietary parameters followed a unimodal response in relation to the latitudinal gradient, with the maximum values for the Tagus and Guadiana populations. Overall, results suggest that this wide interpopulation variability will contribute to the species¿ successful establishment throughout Mediterranean Europe, which poses a serious risk to its highly valuable native fish fauna

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

non present