Chronic urbanization decreases macroinvertebrate resilience to natural disturbances in neotropical streams

Abstract

Natural disturbances play important roles in the functioning and structure of lotic ecosystems, especially in small streams. Adaptation to natural disturbances, in the form of resilience, can be affected by anthropogenic disturbances such as urbanization and industrial zones, which in turn can limit stream biodiversity. The aim of this study was to assess the effects of runoff from urban and industrial zones on the resilience of benthic macroinvertebrate assemblages in small streams. For that, we tested the hypothesis that benthic macroinvertebrate assemblages in streams affected by urbanization and industrialization have lower resilience to natural disturbances than those in reference areas. We calculated the recovery proportions of Taxa Richness, Taxa Abundance, Resistant Taxa Richness, Resistant Taxa Abundance, Sensitive Taxa Richness and Sensitive Taxa Abundance. Recovery proportions of freshwater biodiversity were calculated as the target variable values during the dry season divided by the same variable in the previous rainy season. Taxa Richness recovery proportion and Sensitive Taxa Richness recovery proportion were significantly higher (p < 0.01) in the reference sites. Resistant Taxa Richness and Sensitive Taxa Abundance followed the same pattern but were less significant (p < 0.1). These results indicate that streams draining urban and industrial areas have significantly lower resilience to natural disturbances than their counterparts in reference areas. Our results also suggest that both landscape and local environmental conditions play important roles in maintaining naturally resilient lotic ecosystems and biodiversity in the neotropics.