2026-04-18T03:16:33Zhttps://recercat.cat/oai/request

oai:recercat.cat:10256/227562025-02-13T05:00:02Zcom_2072_452955com_2072_2054col_2072_452959col_2072_453077

00925njm 22002777a 4500 dc Jiménez Carro, Laura author Freixa Casals, Anna author Besolí Mestres, Neus author Sabater, Sergi author 2023-05-01 One of the main effects of global change is the human interference in the global water cycle, which alters river hydrological dynamics and submits their biological communities to hydric stress. Hydric stress is a pulse disturbance with potential multiple effects on biodiversity and functions in river ecosystems. The presence of habitat specialists may support the response of biological communities to pulse disturbances, maintaining ecological functions more consistently than other communities only having generalists. We tested this general hypothesis in stream communities submitted to increasing hydric stress (normal conditions vs humidity vs desiccation). We used communities with variable proportion of specialist algal and cyanobacterial taxa and tested their resistance to hydric stress by analyzing potential changes on their number of species, biovolume, proportion of intact cells, and photosynthetic variables (basal fluorescence, photosynthetic yield). We also evaluated the recovery of ecological functions (net community primary production, community respiration, phosphorus uptake) once hydric stress conditions ended. Hydric stress caused a slight decrease in the number of species and biovolume of assemblages, but the proportion of intact cells did not significantly change because of the disturbance. Basal fluorescence and photosynthetic yield under hydric stress decreased more markedly in communities without specialist taxa, while communities with habitat specialists resisted better. Metabolism did not remarkably decrease under moderate hydric stress, but dropped by half under desiccation in all communities, having or not specialist taxa. Overall, specialist taxa did provide higher resistance to stress but did not support a distinct recovery of ecological functions. We suggest that this characteristic response is related to the high plasticity of biofilm structures This research was funded by the project RIVSTRESS (PID2020-115708RB-C22). ICRA researchers acknowledge funding from the CERCA program and the support through the Consolidated Research Group ICRA-ENV 2021 SGR 01282. AF acknowledges the Juan de la Cierva program (IJC2019-039181-I) funded by MCIN/AEI Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier 6 Ecologia fluvial Stream ecology Estrès hídric Hydric stress Adaptació (Biologia) Adaptation (Biology) Resistance but not recovery is related to the role of specialist taxa in river communities submitted to hydric stress