Hydro-ecoregions of the bolivian Amazon : a geographical framework for the functioning of river ecosystems

We present in this chapter the regional approach of the BIOBAB project, whose aim was to define homogeneous regions as regards the ecological functioning of running waters. The approach consisted of identifying at different hierarchical levels the ecohydrological links between physical control factors and ecosystem structures. Such an approach should provide a global outlook of the natural diversity of aquatic ecosystems in the basin, and by understanding the distribution of the main functional types, to allow some spatial prediction of their most important physical characteristics and associated biota. We shall define, map, and briefly describe the “hydro-ecoregions” of the Bolivian Amazonian basin and present some important aquatic ecosystem characteristics about morphology, hydro-chemistry, and fish and invertebrate communities in the Andean zone. This work is the first attempt to regionalize running water ecosystems in South America, with the end objective to provide a geographical frame for management and conservation. To order the document http://www.cig. ensmp.fr/~iahs/bluebooks/SP6.pdf International Association of Hydrological Sciences The Ecohydrology of South American Rivers and Wetlands Edited by Michael E. McClain The UNESCO Regional Bureau for Science in Europe established in Venice, Italy, provided sponsorship for this publication IAHS Special Publication no. 6 (published December 2002) ISBN 1-901502-02-3; 210 + xiv pp.; price £39.50 The IAHS Series of Special Publications comprises scientific reports prepared by individuals or working parties within the framework of IAHS activities (ISSN 1024-4891) An overview of ecohydrological processes operating in South America’s most important aquatic systems. River reaches ranging from pristine to heavily impacted and processes operating in channels, wetlands, and riparian environments are considered. The Amazon, Orinoco, and Paraná, receive the greatest attention, but the condition of the Piracicaba (São Paulo) and the Paraíba do Sul (Rio de Janeiro) are also evaluated. There is an urgent need for action— many spectacular ecosystems remain to be preserved. The natural attenuation processes in these ecosystems stand to aid South America in achieving its goal for sustainable use of its resources. Ecohydrological processes serve to regulate environmental conditions within aquatic systems, maintaining energy levels, water quantity and water quality, within ranges suitable to native flora and fauna. South America, the wettest and most ecologically diverse continent on Earth with an unrivalled waterscape of giant rivers and wetlands, has great opportunities to capitalize on the natural attenuation effects of ecohydrological processes. South Americans have greatly benefited from the resources derived from their rivers and wetlands, but these aquatic systems have not generally benefited from their association with humans. Dam building, dredging, and canalization are expanding across the continent, eliminating the natural flow regimes of many river reaches and draining wetlands. Much riparian vegetation lying along river margins has been removed. Disturbance of riparian zones has changed the rates of material exchanges from land to aquatic systems, generally increasing erosion and contaminant fluxes. Uncontrolled waste discharges have also degraded water quality in many urban rivers and wetlands, with consequent negative impacts on the health of many urban and downstream rural poor. The chapter titles and contents, and authors, are listed overleaf. This book stems from the IAHS co-sponsored International Symposium on Hydrology and Geochemistry of Large-scale River Basins (with special emphasis on the Amazon and other tropical basins), held November 1999, in Manaus, Brazil. Orders Please send book orders and enquiries to: Mrs Jill Gash tel. : + 44 1491 692442 IAHS Press, Centre for Ecology and Hydrology fax: + 44 1491 692448/692424 Wallingford, Oxfordshire OX10 8BB, UK e-mail: jilly@iahs.demon. co.uk IAHS Members may obtain a discount on books bought for their personal use. Members wanting a discount should ask for it when they place an order—we regret that discounts cannot be backdated. Please note that membership discount will not be given on official purchase orders unless there is an accompanying letter from a member which says that the book(s) ordered will be used by that member for his/her personal use. 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The Ecohydrology of South American Rivers and Wetlands IAHS Special Publ. no. 6 1 Processing of Bioactive Elements in the Amazon River System Emilio Mayorga & Anthony Aufdenkampe Geographical and historical perspectives of the Amazon Role of size on fate and transport Variability and scale in the river system 2 Organic Matter Size Dynamics in the Amazon River Stéphane Mounier, Marc Benedetti, Jean Yves Benaïm & Jacques Boulègue Experiments and results New insights on Amazon discharge chemistry Carbon fluxes Metal ions and carbon Carbon size dynamics Understanding size speciation variation Estimation of carbon fluxes to the estuary 3 Nitrogen Dynamics on the Amazon Flood Plain in Relation to the Flood Pulse of the Solimões River Jürgen Kern, Heidi Kreibich & Assad Darwich Hydrochemistry of the Solimões River and Lake Camaleão Seasonal N processes in flooded and exposed sediments Role of N2 fixation Land-use strategies 4 Total Mercury Distribution and Importance of the Biomagnification Process in Rivers of the Bolivian Amazon Laurence Maurice-Bourgoin & Irma Quiroga Description of the study area Concentrations and distribution of mercury species in surface waters Methodology Total Hg distribution in rivers of the Bolivian Amazon Partitioning of Hg between dissolved and particulate fractions in surface waters Biomagnification and bioaccumulation of Hg in fish Results of total Hg and methylmercury in fish of the Beni, Tuichi and Quiquibey Bioavailability and bioconcentration Biomagnification in the aquatic food chain: basic concepts and in situ evaluations Consequences in riparian populations 5 Hydro-ecoregions of the Bolivian Amazon: a Geographical Framework for the Functioning of River Ecosystems Jean-Gabriel Wasson, Soraya Barrera, Bénédicte Barrère, David Binet, David Collomb, Ismael Gonzales, Franck Gourdin, Jean-Loup Guyot & Giovanna Rocabado Conceptual framework Methodology The hydro-ecoregions of the Bolivian Amazon basin Validation: regional characteristics of running water ecosystems Discussion and perspectives 6 Ecohydrology of Riparian Forests in the Orinoco River Basin Judith Rosales, Conrad Vispo, Nelda Dezzeo, Ligia Blanco-Belmonte, Claudia Knab-Vispo, Nirson Gonzalez, Félix Daza, Chris Bradley, David Gilvear, Gladys Escalante, Noemí Chacón & Geoffrey Petts Ecohydrological interactions in the Caura River flood plain Aquatic invertebrates and fish communities of the lower Caura River Ecohydrological interactions in the confluence zone of the Mapire River Organic litter decomposition in the Mapire vs the Caura 7 Benthic Macroinvertebrates and Physical Habitat Relationships in the Paraná River Flood-plain System Mercedes Marchese, Inés Ezcurra de Drago & Edmundo C. Drago Geographical setting Geomorphology and bed sediments Hydrology Flood-plain lakes Structure and distribution of benthic macroinvertebrates Lateral and temporal dimensions Functional feeding groups 8 Hydrological Controls of Ecological Structure and Function in the Pantanal Wetland (Brazil)