Rivers are dangerously impacted by human activities, with chemical pollution being one of the most pressing concerns. In this context, fluvial biofilms act both as a mirror and as a driver of water quality and are particularly linked to the capacity of the river to provide environmental services. Biofilms have been proposed as early-warning signs of chemical contamination, but exactly what aspect of biofilms is symptomatic of ecosystem service deficiencies? We defined 3 main ecosystem services (i.e. nutrient cycling, carbon uptake, toxicant removal) and 14 associated variables (8 structural, 6 functional) and organic matter decomposition as a proxy for ecosystem functioning, to evaluate epilithic and sediment biofilms as ecosystem service providers (ESPs) in response to pollution. We tested this framework in two different settings: laboratory experiments using simplified fluvial systems, and a snapshot field sampling of 30 rivers along Catalonia (NE Spain, fall 2022) covering a wide array of contamination profiles. Preliminary results from four of the study variables indicate that chemical pollution primarily affected biofilm structure whilst functional endpoints show no obvious pattern yet. With further analyses, we expect to identify keystone aspects of biofilms associated with carbon and nutrient cycling that can be linked to ecosystem service loss and serve as predictors of environmental damage.

Primary Presenter: Nuria Rubio Morales, Centro de Estudios Avanzados de Blanes (nurisarubio@yahoo.com)

Authors:

Nuria Rubio, Centro de Estudios Avanzados de Blanes, CSIC  (nrubio@ceab.csic.es)

Natalia Sanchez Cosijn, Universitat de Girona  (nataliasanchezcos@gmail.com)

Amina Khalid, Universitat de Girona  (amina.khalid@udg.edu)

Berta Bonet, Centro de Estudios Avanzados de Blanes, CSIC  (berta.bonet@ceab.csic.es)

Helena Guasch, Centro de Estudios Avanzados de Blanes, CSIC  (helena.guasch@ceab.csic.es)

Anna Romani, Universitat de Girona  (anna.romani@udg.edu)