title: Metal leaching, acidity, and altitude confine benthic macroinvertebrate community composition in Andean streams.
abstract: Andean streams drain metal-rich bedrock and are subjected to an extreme altitude gradient, which may create highly selective conditions for life. The aim of the present study was to evaluate the combined effects of metals and altitude on benthic macroinvertebrate community composition in Andean streams. Metal-rich sites were characterized by high metal concentrations and low pH, and high-altitude sites were characterized by high ultraviolet-B radiation and low concentrations of dissolved organic matter. Canonical correspondence analysis indicated that the patterns in faunal composition were best explained by metals followed by altitude, with dipterans and collembolans occurring mostly under harsh conditions of high altitude and high metal levels. Interaction between metals and altitude was most evident at metal-rich sites. It is suggested that in Andean streams, metal leaching from igneous rock and altitude may be important factors confining benthic macroinvertebrate communities, reducing their numbers and changing their composition toward specialized taxa.
authors.affiliation: Laboratory of Ecotoxicology, Faculty of Sciences and Philosophy, Universidad Peruana Cayetano Heredia, Lima, Peru; Institute for Biodiversity and Ecosystem Dynamics, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Raúl A
authors.initials: RA
authors.lastname: Loayza-Muro
authors.forename: Joost F
authors.initials: JF
authors.lastname: Duivenvoorden
authors.forename: Michiel H S
authors.initials: MH
authors.lastname: Kraak
authors.forename: Wim
authors.initials: W
authors.lastname: Admiraal
mesh_terms: D000531:Altitude; D000818:Animals; D001151:Arsenic / Q000032:analysis* / Q000737:chemistry; D044822:Biodiversity; D055593:Geological Phenomena; D006863:Hydrogen-Ion Concentration; D007448:Invertebrates / Q000145:classification*; D008670:Metals / Q000032:analysis* / Q000737:chemistry; D010568:Peru; D045483:Rivers / Q000737:chemistry; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical; D001151:Arsenic
keywords: Andean stream; Community composition; High altitude; Macroinvertebrate; Metal leaching