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Hydro-Écologie Des Communautés D'invertébrés Aquatiques Dans Les

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Hydro-Écologie Des Communautés D'invertébrés Aquatiques Dans Les Université Pierre et Marie Curie Ecole doctorale du Muséum « Sciences de la Nature et de l'Homme » Laboratoire Évolution, Génomes et Spéciation Équipe Diversité, Écologie et Évolution des Insectes Tropicaux Hydro-écologie des communautés d’invertébrés aquatiques dans les rivières glaciaires équatoriennes Par Sophie Cauvy-Fraunié Thèse de doctorat en Écologie Dirigée par Olivier Dangles Présentée et soutenue publiquement le 10 Octobre 2014 Devant un jury composé de : M. Olivier DANGLES, DR, IRD-LEGS Directeur de thèse M. Christopher ROBINSON, DR, EAWAG Rapporteur M. Nicolas LAMOUROUX, DR, IRSTEA Rapporteur M. Alexander MILNER, DR, Univ. Birmingham Examinateur M. Thomas CONDOM, CR, IRD-LTHE Examinateur M. Nicolas LOEUILLE, HDR, UPMC Examinateur 1 2 Université Pierre et Marie Curie Ecole doctorale du Muséum « Sciences de la Nature et de l'Homme » Laboratory Évolution, Génomes et Spéciation Diversité, Écologie et Évolution des Insectes Tropicaux Hydroecology of invertebrate communities in equatorial glacier-fed streams By Sophie Cauvy-Fraunié Doctoral thesis in Ecology Headed by Olivier Dangles Defended on 10 October 10th 2014 in front of the jury composed by M. Olivier DANGLES, DR, IRD-LEGS Supervisor M. Christopher ROBINSON, DR, EAWAG Reviewer M. Nicolas LAMOUROUX, DR, IRSTEA Reviewer M. Alexander MILNER, DR, Univ. Birmingham Examiner M. Thomas CONDOM, CR, IRD-LTHE Examiner M. Nicolas LOEUILLE, HDR, UPMC Examiner 3 4 ACKNOWLEDGEMENTS To Olivier Dangles for teaching me Research. For sharing his knowledge and experience, for his enthusiastic involvement in my thesis and his guidance. For always having time for discussion, but also for all his continued encouragements, and moral support. Merci +++ ;-) To Dean Jacobsen for all his relevant comments and advice, for his participation to the entire study, and for his support and his friendship. Tak! To Thomas Condom for his insightful comments and advice, for teaching me concepts in hydrology, for his participation to the paper HESS and for his friendship. To Fabien Anthelme for his advice, support and kindness. To Antoine Rabatel for his relevant comments and his participation to the paper HESS. To Rodrigo Espinosa and Patricio Andino for their warmly welcome, for their patience to teaching me Spanish, laboratory and field works and for technical support in the field. To all the people that gave a hand in the field and laboratory in Ecuador: Andres Morabowen, Vincent Fugère, Belen Liger, Gabriel Mosquera, Ricardo Mogollón, Daniela Cueva, Cristina Ibarra, Philip Brask Madsen. To Rafael Cárdenas for his support and for revising mi abstract in Spanish. To Ruben Basantes Serrano and Maëlle Collet for computing and providing me the glacier outlines. To Gaëlle Boutin for providing a considerable administrative assistance. To Francois Rebaudo for his advice, his technical and administrative assistance and for his warmly welcome in the LEGS laboratory. To the DEEIT team in Gif-sur-Yvette, especially Jean-Francois Silvain, for their hospitality during my stay in the laboratory (LEGS) and for their interest in my work. 5 To the French Institute for Development (IRD) in Quito (Ecuador) and in La Paz (Bolivia). Special thanks to Aída Melgarejo, Ivan Cangas, Marie Garino, Alex Terrazas, Bernard Francou and Jacques Gardon for their efficiency in administrative support. To the Laboratoy of Entomology at the Facultad de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador (Quito, Ecuador) for always providing an enjoyable place to work, and part of the material used in the experiments and laboratory analyses. Special acknowledgements to Alvaro Barragan and Veronica Crespo-Perez. To the Laboratory of Limnology at the Instituto de Ecología, Universidad Mayor San Andrés (La Paz, Bolivia) for their hosting in 2012-2013, especially to Julio Pinto and Ruben Marin and Estefanía Quenta for their welcome. To my friends Pierre Semana, Justin Eyquem, Delphine Lethimonier, Antonin Pépin, Pierre- Marie Assimon, and Flavia Tamayo, Valeria Tamayo, Andrea Tamayo, Daniela Lopez, Cristina Arias for providing me their comfy couch during the last year in Paris and in Quito. To my friends Clio Randimbivololona, Isabel Moreno, Pauline Bonneviot, Lucile Lejemble, Diane Sanchez, and Florie Moranville for their moral support throughout my thesis and for hosting me every time in Paris. To my family, especially my parents, my brothers and my nephews, for their love and their moral support throughout my thesis. To my boyfriend, Emile Faye, for his unconditional moral support throughout my thesis, for his help and advice in many situations. For his patience, and doing everything the last weeks. With love. 6 ABSTRACT In the face of climate change, freshwater species in glacierized catchments are confronted to modifications in glacier runoff, linked to the acceleration of glacier retreat. This thesis aims to evaluate the effect of glacial meltwater contribution to alpine streams flow on the organization of aquatic communities in a glacierized catchment in the tropical Andes (Antisana, Ecuador). At different spatial and temporal scales, we quantified glacial influence, determined its effects on aquatic macroinvertebrate communities and anticipated the possible consequences of glacier retreat on aquatic biodiversity. We first examined at the stream reach scale, the effect of the temporal variability in hydraulic stress generated by daily glacial floods on macroinvertebrates. Then at the catchment scale, we assessed the effect of spatial and temporal variability in glacial influence on macroinvertebrates community composition. For this, we developed new quantitative indices of glacial influence based on the diurnal flow variation identified by performing wavelet analyses on water level time series. Finally, we evaluated the effect of glacial meltwater contribution to alpine streams flow on the macroinvertebrate metacommunity structure and dynamics within the entire catchment. At the stream reach scale, macroinvertebrate communities were poorly affected by the diurnal increase in hydraulic stress caused by daily glacial floods occurring all year round in the tropics. However, although those high flow events were frequent, temporal variability in flood intensity generated temporal β-diversity. At the catchment scale, local diversity peaked at intermediate level of glacial influence. In addition, metacommunity was structured by environmental filtering and dispersal processes among which glacial influence was not only the main environmental filter but also a significant factor limiting aquatic dispersion. Thus, glacial meltwater also engendered high spatial β-diversity. We expect that reduction in glacier runoff would diminish hydraulic stress and harshness within glacier-fed streams and thereby spatial and temporal environmental heterogeneity within the catchment. Those changes would probably reduce both environmental filtering and aquatic dispersal limitation, allowing thus more generalist species not adapted to the harshness of glacial meltwater to colonize and establish throughout the entire catchment. Therefore, we assume that glacier retreat would provoke the extinction of specialized species adapted to glacier runoff (loss of α-diversity) and to a taxonomic homogenization of the aquatic fauna within the catchment (decrease in spatial and temporal β-diversity), both resulting in an irreversible reduction in regional diversity. Keywords: climate change, glacier retreat, glacier-fed stream, hydroecology, aquatic macroinvertebrates, freshwater ecosystem structure, tropical Andes, Antisana, Ecuador. 7 8 RESUMEN Hidroecología de las comunidades de invertebrados en los ríos glaciares del Ecuador Frente al cambio climático, las especies de agua dulce en las cuencas glaciares se enfrentan a modificaciones del caudal glaciar relacionado con la aceleración del retroceso glaciar. El objetivo de esta tesis es evaluar la contribución de las aguas glaciares en la organización de las comunidades de organismos acuáticos en ríos alpinos de una cuenca glaciar en los Andes tropicales (Antisana, Ecuador). Para esto, a diferentes escalas espaciales y temporales, cuantificamos la influencia glaciar, determinamos sus efectos sobre las comunidades de macroinvertebrados acuáticos y anticipamos las posibles consecuencias del retroceso glaciar sobre la biodiversidad acuática. En una primera instancia, a escala del río examinamos el efecto de la variabilidad temporal del estrés hídrico generado por las crecidas glaciares diarias sobre los macroinvertebrados. En una segunda instancia, a escala de la cuenca, evaluamos el efecto de la variabilidad espacial y temporal de la influencia glaciar sobre la composición de las comunidades de macroinvertebrados. Para ello, desarrollamos nuevos índices cuantitativos de influencia glacial basados en la variación diurna del flujo identificado mediante la realización de análisis de ondículas de series temporales de nivel de agua. Finalmente, evaluamos el efecto de la contribución de las aguas glaciares al flujo de ríos sobre la estructura y la dinámica de la metacomunidad de macroinvertebrados dentro de toda la cuenca. A escala del río, la comunidad de macroinvertebrados fue levemente afectada por el aumento diurno del estrés hídrico causado por las crecidas glaciares diarias a lo largo de un año. Aunque los eventos de alto flujo fueron muy frecuentes, la variabilidad temporal de la intensidad del flujo generaba β-diversidad temporal. Por otra parte, a escala de la cuenca, la diversidad local alcanzó su
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