Assessing the effects of urbanization on streams in Tierra del Fuego

Abstract

We set out to understand how urbanization affects streams in Ushuaia, Tierra del Fuego. Paired ttestsand linear regressions were used to compare physico-chemical stream habitat variables (i.e., temperature,turbidity, conductivity, dissolved oxygen and pH) and benthic macroinvertebrate community structure (i.e.,density, taxonomic richness, Shannon-Weiner diversity) and function (functional feeding groups [FFG]) in fourwatersheds with urban and reference sites. We then calculated indices of biotic integrity for habitat (rapid visualassessment protocol [RVAP]) and benthos (Ephemeroptera, Plecoptera, Trichoptera richness [EPT], family bioticindex [FBI], rapid bioassessment protocol [RBP] and biotic monitoring Patagonian streams [BMPS]). Resultsindicated that urbanization negatively impacted these streams? underlying ecological condition, decreasingbenthic biodiversity and dissolved oxygen, while increasing conductivity and turbidity. FFG assemblagewas similar between both sites, but urbanization increased the existing dominance of collector-gatherers.Additionally, urban sites presented lower values in three of the benthic macroinvertebrate indices (EPT, RBP,BMPS, but not FBI) and also for habitat (RVAP). These data fill an existing gap in stream ecology for southernPatagonia and are useful to create monitoring tools. By incorporating urbanization as a driver of ecosystemchange, managers and planners will be better able to confront the issue of sustainable development in thisregion, which is considered one of the most pristine wilderness areas remaining on the planet but whosehuman population is concentrated in a few densely populated urban areas.