Assessing Urban Impacts on Water Quality,

MISERENDINO M.L; BRAND C.; DI PRINZIO C.Y.

Water Air Soil Pollut

Año: 2008 p. 1 - 20

Communities of aquatic macroinvertebrates,fish density and biomass, and environmentalvariables were investigated in three Patagonianmountain rivers affected by urbanization. The riversLas Minas, Esquel and Carbón that flow through thetowns of Cholila, Esquel and Corcovado, respectively(northwest Chubut, Argentina) were selected to assessthe degree of impairment. A reference site and anurban site were established on each river. Waterquality variables including conductivity, majornutrients, total suspended solids (TSS) and dissolvedoxygen, habitat conditions and quality of riparianecosystems were investigated in autumn, winter,spring and summer 2005–2006. Macroinvertebrateswere sampled concurrently in three riffles and threepools at each site. Invertebrate species richness, EPTrichness, the Shannon–Weaver diversity index, %EPT density, and the BMPS index were lower aturban sites, whereas % collectors increased. The mostimpaired site was below Esquel, the largest town.Senzilloides panguipulli (Plecoptera), Polypedilumand Rheotanytarsus species (Diptera: Chironomidae),Nais communis (Oligochaeta) and Meridialaris chiloeensis(Ephemeroptera) dominated assemblages atreference and moderately impaired sites in summer,whereas the strongly polluted reach below Esquel hadlow flow in summer and a community dominated byLimnodrilus spp. (Oligochaeta), Helobdella spp.(Hirudinea), and two Hyallela species (Amphipoda).Canonical correspondence analysis indicated thatammonia, conductivity and TSS were importantvariables structuring invertebrate assemblages. Incontrast, fish density and biomass varied in a nonsystematicmanner among sites. Overall, urbanizationresulted in varying degrees of habitat degradation,sedimentation and nutrient enrichment that werereflected by the macroinvertebrate assemblages,which can be used effectively to monitor the effectsof urban communities on Patagonian mountainstreams.