Limited effects of structural restoration on ecosystem functioning in an urban tropical stream

Abstract Introduction Hydromorphological restoration through structural interventions is commonly used to mitigate urbanization impacts on lotic freshwater systems, but their effects on ecosystem functioning in urban tropical streams remain unexplored. Objectives Here, we aimed at evaluating the short‐term effects of the deployment of cross‐vanes and riffles in a third‐order urban tropical stream on indicators of ecosystem structure (e.g. water quality, hydrodynamics, and substrate diversity) and functioning, including ammonium–nitrogen () and soluble reactive phosphorus (SRP) uptake, as well as whole‐stream metabolism. Methods The assessed indicators were compared before (March–December 2022) and after (October 2023–April 2024) restoration, as well as against reference conditions. Results Post‐restoration, the stream became significantly wider and shallower, with increased sand and gravel content and enhanced transient storage zone effectiveness. However, gross primary production was reduced, while ecosystem respiration and and SRP uptake efficiencies remained unchanged. Despite some notable improvements, all ecosystem functions still differed from those observed in reference streams. Conclusions Our results point to challenges in effective structural restoration of larger streams and suggest that reach‐scale restoration measures in urban areas should be integrated with upland best management practices to enhance their effectiveness. These insights are critical for informing future structural in‐situ restoration projects.