Response of sub-Antarctic streams to urbanization: Relevance of assemblage structure and independent reference areas

TAGLIAFERRO, MARINA; GRANITTO, MARIA; RODRÍGUEZ, PATRICIA; ANDERSON, CHRISTOPHER B.

LIMNOLOGICA

ELSEVIER GMBH

Año: 2022 vol. 93

0075-9511

Andean Patagonia is experiencing sudden changes due to unorganized urban expansion. Despite being known forits wilderness areas, southern Patagonian urban streams have been increasingly studied during the last decade,using reference-impact gradients within urbanizing watersheds. Here, we assess urbanization effects on streamintegrity by comparing environmental characteristics on independent reference streams vs. urban streams, andthe benthic macroinvertebrate community structure along three stream reaches in an urbanization gradient. Incomparison to reference sites, urban streams had higher nutrient concentrations, temperature, turbidity, streamflow, and total primary producer biomass, accompanied by lower dissolved oxygen concentrations, substrateparticle size, mainly along mid and downstream areas. These variables were the main factors structuring macroinvertebrateassemblage ordination analysis. Macroinvertebrate assemblages from areas upstream from theurbanization differed from their counterparts in reference streams, but not from downstream reference areas.Environmental characteristics and biotic assemblage structure were altered in urban streams, even in reacheslocated upstream from urbanization, compared to independent upstream reference reaches. This study highlightsthe importance of a community and comparative vision towards independent areas with low impact to serve asreference values and establish appropriate goals or baselines when assessing ecological conditions and potentialrestoration.