Assessing the performance of macroinvertebrate metrics in the Challhuaco-Ñireco System (Northern Patagonia, Argentina)

MAUAD MELINA; MISERENDINO MARIA LAURA; RISSO MIGUEL ANGEL; MASSAFERRO JULIETA

IHERINGIA. SéRIE ZOOLOGIA

FUNDACAO ZOOBOTANICA RIO GRANDE SUL

Lugar: Porto Alegre; Año: 2015 vol. 105 p. 348 - 358

0073-4721

Seven sites were examined in the Challhuaco-Ñireco system, located in the reserve of the Nahuel Huapi National Park, however partof the catchment is urbanized, being San Carlos de Bariloche (150,000 inhabitants) placed in the lower part of the basin. Physico-chemical variableswere measured and benthic macroinvertebrates were collected during three consecutive years at seven sites from the headwater to the river outlet.Sites near the source of the river were characterised by Plecoptera, Ephemeroptera, Trichoptera and Diptera, whereas sites close to the river mouthwere dominated by Diptera, Oligochaeta and Mollusca. Regarding functional feeding groups, collector-gatherers were dominant at all sites andthis pattern was consistent among years. Ordination Analysis (RDA) revealed that species assemblages distribution responded to the climatic andtopographic gradient (temperature and elevation), but also were associated with variables related to human impact (conductivity, nitrate and phosphatecontents). Species assemblages at headwaters were mostly represented by sensitive insects, whereas tolerant taxa such as Tubificidae, Lumbriculidae,Chironomidae and crustacean Aegla sp. were dominant at urbanised sites. Regarding macroinvertebrate metrics employed, total richness, EPT taxa,Shannon diversity index and Biotic Monitoring Patagonian Stream index resulted fairly consistent and evidenced different levels of disturbances atthe stream, meaning that this measures are suitable for evaluation of the status of Patagonian mountain streams.