title: Invertebrate Metacommunity Structure and Dynamics in an Andean Glacial Stream Network Facing Climate Change.
abstract: Under the ongoing climate change, understanding the mechanisms structuring the spatial distribution of aquatic species in glacial stream networks is of critical importance to predict the response of aquatic biodiversity in the face of glacier melting. In this study, we propose to use metacommunity theory as a conceptual framework to better understand how river network structure influences the spatial organization of aquatic communities in glacierized catchments. At 51 stream sites in an Andean glacierized catchment (Ecuador), we sampled benthic macroinvertebrates, measured physico-chemical and food resource conditions, and calculated geographical, altitudinal and glaciality distances among all sites. Using partial redundancy analysis, we partitioned community variation to evaluate the relative strength of environmental conditions (e.g., glaciality, food resource) vs. spatial processes (e.g., overland, watercourse, and downstream directional dispersal) in organizing the aquatic metacommunity. Results revealed that both environmental and spatial variables significantly explained community variation among sites. Among all environmental variables, the glacial influence component best explained community variation. Overland spatial variables based on geographical and altitudinal distances significantly affected community variation. Watercourse spatial variables based on glaciality distances had a unique significant effect on community variation. Within alpine catchment, glacial meltwater affects macroinvertebrate metacommunity structure in many ways. Indeed, the harsh environmental conditions characterizing glacial influence not only constitute the primary environmental filter but also, limit water-borne macroinvertebrate dispersal. Therefore, glacier runoff acts as an aquatic dispersal barrier, isolating species in headwater streams, and preventing non-adapted species to colonize throughout the entire stream network. Under a scenario of glacier runoff decrease, we expect a reduction in both environmental filtering and dispersal limitation, inducing a taxonomic homogenization of the aquatic fauna in glacierized catchments as well as the extinction of specialized species in headwater groundwater and glacier-fed streams, and consequently an irreversible reduction in regional diversity.
authors: IRD, Institut de Recherche pour le Développement, UMR EGCE, IRD-247 CNRS-UP Sud-9191, 91198 Gif-sur-Yvette cedex, France; Pontificia Universidad Católica del Ecuador, Facultad de Ciencias Exactas y Naturales, Quito, Ecuador; Instituto de Ecología, Universidad Mayor San Andrés, Cotacota, La Paz, Bolivia.
authors: Sophie
authors: S
authors: Cauvy-Fraunié
authors: Pontificia Universidad Católica del Ecuador, Facultad de Ciencias Exactas y Naturales, Quito, Ecuador.
authors: Rodrigo
authors: R
authors: Espinosa
authors: Pontificia Universidad Católica del Ecuador, Facultad de Ciencias Exactas y Naturales, Quito, Ecuador.
authors: Patricio
authors: P
authors: Andino
authors: Pontificia Universidad Católica del Ecuador, Facultad de Ciencias Exactas y Naturales, Quito, Ecuador; Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark.
authors: Dean
authors: D
authors: Jacobsen
authors: IRD, Institut de Recherche pour le Développement, UMR EGCE, IRD-247 CNRS-UP Sud-9191, 91198 Gif-sur-Yvette cedex, France; Pontificia Universidad Católica del Ecuador, Facultad de Ciencias Exactas y Naturales, Quito, Ecuador; Instituto de Ecología, Universidad Mayor San Andrés, Cotacota, La Paz, Bolivia.
authors: Olivier
authors: O
authors: Dangles
mesh_terms: D000818:Animals; D001118:Argentina; D044822:Biodiversity; D057231:Climate Change; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D046448:Ice Cover; D007448:Invertebrates / Q000145:classification / Q000502:physiology*; D011157:Population Dynamics; D045483:Rivers