Biotic diversity of benthic macroinvertebrates at contrasting glacier-fed systems in Patagonia Mountains: The role of environmental heterogeneity facing global warming

MISERENDINO MARÍA LAURA; BRAND CECILIA; EPELE LUIS BELTRAN; DI PRINZIO CECILIA YANINA; OMAD GUILLERMO HUGO; ARCHANGELSKY MIGUEL; MARTÍNEZ, OSCAR N.; KUTSCHKER ADRIANA

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 622- p. 152 - 163

0048-9697

Patagonia is by far the largest glacierized area in South America. However, little is known about ecology, functioningand biodiversity of glacier-fed streams facing global warming.Weinvestigated changes in environmental featuresand macroinvertebrate communities along a longitudinal gradient of glacier influence of two Patagoniansystems that differ in glacier cover magnitude and the spatial sequence of lotic and lentic phases. Both glaciers,Torrecillas (~5.5 km2, Torrecillas system) and Cónico (~0.44 km2, Baggilt system), are retreating. Longitudinaldistribution of benthic invertebrates partially fitted to predictions for glacierized temperate systems, withDiamesinae spp. dominating at closest sites to the Cónico, and Orthocladiinae increasing downstream, but patternswere unclear at Torrecillas. Generalized Linear Model identified chlorophyll a and conductivity as havingsignificant effect on richness and density respectively at Torrecillas; detritus biomass and gravel influenced speciesrichness, and boulder percentage and water temperature affected density, at Baggilt. Canonical CorrespondenceAnalyses integrating benthic biota and environmental variables revealed that a higher environmentalheterogeneity at Baggilt, related with spatial dimension (unshaded/shaded reaches, wetland reaches), local resources(detritus, bryophytes) and temperature, probably explained the unexpected high richness in benthic assemblages(67 taxa). Environmental conditions imposed by the lake outlet (proglacial) at Torrecillas resulted in aless diverse community (31 taxa). Finally our results suggest that thesei solated, small glacier-fed streams typicalof the Patagonian landscape appear highly vulnerable to global warming. Endemic elements could disappear atupper segments being replaced by other species common at rhithral environments, which might increase local diversity (alfa diversity) but decrease regional diversity (gamma diversity). From an ecosystem perspective stream functioning can result altered. Glacier retreating or disappearing threatens major ecosystem services for Patagonian inhabitants such as water supply, hydrological regulation, recreation and tourism