title: Direct and indirect effects of glaciers on aquatic biodiversity in high Andean peatlands.
abstract: The rapid melting of glacier cover is one of the most obvious impacts of climate change on alpine ecosystems and biodiversity. Our understanding of the impact of a decrease in glacier runoff on aquatic biodiversity is currently based on the 'glacier-heterogeneity-diversity' paradigm, according to which there is high α-diversity at intermediate levels of glacial influence due to the high degree of environmental heterogeneity caused by glacier water. This α-diversity pattern generates high levels of between-site aquatic community variation (high β diversity) and increases regional diversity (γ-diversity). There is a rich conceptual background in favor of this paradigm, but empirical data supporting it are scarce. We investigated this paradigm by analyzing the different diversity patterns (α, β and γ-diversity) of four aquatic groups (zooplankton, macroinvertebrates, algae and macrophytes) living in high-elevation peatlands (>4500 m above sea level). We sampled 200 pools from 20 peatlands along a glacier gradient in the Cordillera Real of Bolivia. We performed structural equation modeling (SEM) to analyze the potential mechanisms underlying the observed diversity patterns. Intermediate levels of glacial influence (15-20% cover) resulted in high heterogeneity, but α-diversity responded to glacial influence only for the zooplankton group (Cladocera). Our SEM analysis did not identify environmental heterogeneity as a significant variable explaining the relationship between glacier and α-diversity. Peatland area had a strong positive effect on heterogeneity and diversity. β-diversity was significantly associated with glacier gradient, and 12.9% of the total regional diversity (γ-diversity) was restricted to peatlands with a high degree of glacial influence. These species might be lost in a context of glacial retreat. These findings provide new insight into the potential effects of glacial retreat on the aquatic environment and biodiversity in the peatlands of the tropical Andes.
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte (IRBI), Université François-Rabelais, Tours, Tours, 37200, France.|Institut de Recherche pour le Développement (IRD), UMR EGCE-UnivParisSud-CNRS-IRD-ParisSaclay, Gif-sur Yvette, 91198, France.|Unidad de Limnología, Instituto de Ecología, Universidad Mayor San Andrés, calle 27 Cota Cota, La Paz, Bolivia.
authors.forename: Estefania
authors.initials: E
authors.lastname: Quenta
authors.affiliation: Unidad de Limnología, Instituto de Ecología, Universidad Mayor San Andrés, calle 27 Cota Cota, La Paz, Bolivia.
authors.forename: Jorge
authors.initials: J
authors.lastname: Molina-Rodriguez
authors.affiliation: Unidad de Limnología, Instituto de Ecología, Universidad Mayor San Andrés, calle 27 Cota Cota, La Paz, Bolivia.
authors.forename: Karina
authors.initials: K
authors.lastname: Gonzales
authors.affiliation: Institut de Recherche pour le Développement (IRD), UMR EGCE-UnivParisSud-CNRS-IRD-ParisSaclay, Gif-sur Yvette, 91198, France.|Centro de Análisis Espacial, Instituto de Ecología, Universidad Mayor San Andrés, calle 27 Cota Cota, La Paz, Bolivia.
authors.forename: François
authors.initials: F
authors.lastname: Rebaudo
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte (IRBI), Université François-Rabelais, Tours, Tours, 37200, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Casas
authors.affiliation: Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100, Copenhagen, Denmark.|Escuela de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, 12 de Octubre, 1076 y Roca, Quito, Ecuador.
authors.forename: Dean
authors.initials: D
authors.lastname: Jacobsen
authors.affiliation: Institut de Recherche pour le Développement (IRD), UMR EGCE-UnivParisSud-CNRS-IRD-ParisSaclay, Gif-sur Yvette, 91198, France.|Escuela de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, 12 de Octubre, 1076 y Roca, Quito, Ecuador.
authors.forename: Olivier
authors.initials: O
authors.lastname: Dangles
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D044822:Biodiversity; D001838:Bolivia; D057231:Climate Change; D017753:Ecosystem; D046448:Ice Cover
keywords: aquatic biodiversity; environmental heterogeneity; glacial influence; high Andean peatlands; peatland area; tropical Andes