Impacts of diffuse urban stressors on stream benthic communities and ecosystem functioning: A review
Authors: Colls Miriam , Viza Aida , Zufiarre Aitziber , Camacho-Santamans Alba , Laini Alex , González-Ferreras Alexia Maria , Filipe Ana Filipa , Pérez-Calpe Ana Victoria , Freixa Anna , Lupon Anna , Santamans Anna C. , Pradhan Arunava , Espinosa Carmen , Vera-Trujillo Carmen , Gutiérrez-Cánovas Cayetano , Mendoza-Lera Clara , Bruno Daniel , Mercado-Bettin Daniel , Morant Daniel , Batista Daniela , Cunillera-Montcusi David , Graça Diana , Vico-Oton Eduard , Estévez Edurne , Leon-Palmero Elizabeth , Suarez Ena Lucia , Fenoy Encarnación , Lima Eva , Picazo Félix , Oficialdegui Francisco J. , Keck François , Gionchetta Giulia , Sabas Ibor , Pérez-Silos Ignacio , Antunes Ilisa , Alvarez-Manzaneda Inmaculada , de Guzmán Ioar , Fernandes Isabel , Pereira da Silva Janine , Wei Jing , Montes-Pérez Jorge Juan , Trabulo José , Ledesma José L. J. , Fernandez-Calero José Maria , Ramião José Pedro , Rubio-Rios Juan , Gonzalez-Trujillo Juan David , Barral-Fraga Laura , Jiménez Laura , Vendrell-Puigmitja Lidia , Bertrans Lluís , Gomez-Gener Lluís , Rovelli Lorenzo , Thuile-Bistarelli Lukas , Sanchez-Morales Marc , Cabrerizo Marco J. , Aranguren-Gassis Maria , Argudo Maria , Navarro-Ramos Maria J. , Atristain Miren , Lopez-Rojo Naiara , Valiente Nicolás , Perujo Nuria , Pereda Olatz , Llanos-Paez Oriana , Belmar Oscar , Tascon-Peña Osvaldo , Rodriguez-Lozano Pablo , Sánchez de Pedro Raquel , Arias-Real Rebeca , Bolpagni Rossano , del Campo Rubén , Poblador Silvia , Guareschi Simone , Hilgert Stephan , Duarte Sofia , Rodriguez-Castillo Tamara , Chonova Teofana , Conejo-Orosa Teresa , Céspedes Vanessa , Granados Verónica , Osorio Victor , Vázquez Víctor , Martin-Vélez Víctor , Romero Ferran 
Published: May 2023

Catchment urbanisation results in urban streams being exposed to a multitude of stressors. Notably, stressors originating from diffuse sources have received less attention than stressors originating from point sources. Here, advances related to diffuse urban stressors and their consequences for stream benthic communities are summarised by reviewing 92 articles. Based on the search criteria, the number of articles dealing with diffuse urban stressors in streams has been increasing, and most of them focused on North America, Europe, and China. Land use was the most common measure used to characterize diffuse stressor sources in urban streams (70.7 % of the articles characterised land use), and chemical stressors (inorganic nutrients, xenobiotics, metals, and water properties, including pH and conductivity) were more frequently reported than physical or biological stressors. A total of 53.3 % of the articles addressed the impact of urban stressors on macroinvertebrates, while 35.9 % focused on bacteria, 9.8 % on fungi, and 8.7 % on algae. Regarding ecosystem functions, almost half of the articles (43.5 %) addressed changes in community dynamics, 40.3 % addressed organic matter decomposition, and 33.9 % addressed nutrient cycling. When comparing urban and non-urban streams, the reviewed studies suggest that urbanisation negatively impacts the diversity of benthic organisms, leading to shifts in community composition. These changes imply functional degradation of streams. The results of the present review summarise the knowledge gained to date and identify its main gaps to help improve our understanding of urban streams.