Rapid Assessment Program 15 Bulletin of Biological Assessment A Biological Assessment of the Aquatic Ecosystems of the Upper Río Orthon Basin, Pando, Bolivia Barry Chernoff and Philip W. Willink, Editors CONSERVATION INTERNATIONAL THE FIELD MUSEUM MUSEO NACIONAL DE HISTORIA NATURAL - BOLIVIA Bulletin of Biological Assessment is published by: Conservation International Center for Applied Biodiversity Science Department of Conservation Biology Rapid Assessment Program 2501 M Street NW, Suite 200 Washington, DC 20037 USA 202-429-5660 202-887-0193 fax www.conservation.org Editors: Barry Chernoff and Philip W. Willink Assistant Editors: Leeanne E. Alonso and Jensen Reitz Montambault Design: Glenda P. Fábregas Maps: Philip W. Willink Cover photograph: Theresa Bert Translations: María del Carmen Arce S. Conservation International is a private, non-profit organization exempt from federal income tax under section 501 c(3) of the Internal Revenue Code. ISBN 1-881173-30-5 1999 by Conservation International. All rights reserved. Library of Congress Card Catalog Number 99-069140 The designations of geographical entities in this publication, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of Conservation International or its supporting organizations concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. Any opinions expressed in the Bulletin of Biological Assessment are those of the writers and do not necessarily reflect those of Conserva- tion International or its co-publishers. Bulletin of Biological Assessment was formerly RAP Working Papers. Numbers 1-14 of this series were published under the previous title. Suggested citation: Chernoff, B. and P.W. Willink (Editors). 1999. A biological assessment of the aquatic ecosystems of the Upper Río Orthon basin, Pando, Bolivia. Bulletin of Biological Assessment 15. Conservation International, Washington, DC 2 CONSERVATION INTERNATIONAL Rapid Assessment Program PREFACE From 4 - 20 September 1996 a team of 21 scientists undertook the first AquaRAP expedition to northern Bolivia, State of Pando, in the Tahuamanu and Manuripi river systems upstream from their confluence at the town of Puerto Rico (see Maps 1, 2 and 3). The scientific team was multinational and multidisciplinary. They came from Bolivia, Brazil, Perú, Paraguay, Venezuela and the United States. The scientists were specialists in aquatic and terrestrial botany; crustaceans and macro-invertebrates; population genetics; ichthyology; and limnology, including water chemistry and plankton. The AquaRAP team contained both established scientists and students. The expedition was focused primarily upon the biological and conservation value of the region as well as upon the current and future threats facing the region. However, the expedition was also intended to evaluate the protocols for rapidly assessing aquatic ecosystems. The organization of this report begins with an executive summary which includes a brief overview of the physical and terrestrial characteristics of the region, as well as summaries of the chapters from each of the scientific disciplines, and concludes with recommendations for a conservation strategy. We then present the biological results from limnology, decapod crustaceans, fishes and genetics. The limnology group combines water chemistry with plankton and benthos. Although traditionally these disciplines have been separated, we combine what should be integrated. The disciplinary chapters are written as scientific papers, each self-contained with its own literature citations for ease of use. After the scientific papers we include a glossary of terms and the appendices with much of the raw data. Explanations may be needed for the terms diversity and species richness. In vernacular usage diversity, when used in the context of biological organisms, refers to the numbers of and variety of types of species, organisms, taxa, etc. In the ecological literature, diversity takes on a slightly different meaning, referring to not only the number of entities but also their relative abundances. Such use of diversity can be found in Chapter 1. In this volume diversity is used in two ways: i) in the general, vernacular sense we occasionally refer to the “diversity of organisms”, meaning the number of and variety of organisms; but ii) in the ecological sense, we refer to “low or high diversity”, meaning “diversity” as calculated from a specific formula. Note that in the vernacular usage, diversity is never modified by high or low or used in a comparative way. With the exception of the limno- logical assessment, given the nature of rapid assessment we are unable to evaluate abundances of organisms in a quantitative fashion. Therefore, most of the disciplinary chapters reference only the number of species captured. From the ecological literature, the term species richness means the number of species. We use species richness in several chapters (e.g., Chapter 5) when referring to the number of species present in a habitat or river basin. This report is intended to be used by decision makers, environmental managers, governmental and non-governmental agencies, students, and scientists. The novel information and analyses presented herein have two aims: (i) that we have pre- sented a compelling case and cogent strategy for conservation efforts within the region; and (ii) that the scientific data and analyses will stimulate future scientific research of this critical region. We have attempted in this volume not simply to present an inventory of the organisms that we encountered during our expedition but rather to use that information to evaluate conservation strategies under different scenarios of environmental threat (e.g., Chapter 5). We welcome comments and criticisms as we continue to evolve AquaRAP and the methods used for evaluating conservation strategies from biological data. Barry Chernoff Philip W. Willink BULLETIN OF BIOLOGICAL ASSESSMENT FIFTEEN December 1999 3 TABLE OF CONTENTS 3 Preface 27 1. Water Quality, Zooplankton and Macroinvertebrates of the Río 6 Participants Tahuamanu and the Río Nareuda Francisco Antonio R. Barbosa, Fernando Villarte 8 Organizational Profiles V., Juan Fernando Guerra Serrudo, Germana de 10 Acknowledgments Paula Castro Prates Renault, Paulina María Maia-Barbosa, Rosa María Menéndez, Marcos 11 Report at a Glance Callisto Faria Pereira, and Juliana de Abreu Vianna 12 Informe de un Vistazo 35 2. Diversity and Abundance of Decapod 13 Executive Summary and Overview Crustaceans in the Río Tahuamanu Barry Chernoff and Philip W. Willink and Río Manuripi Basins Célio Magalhães 13 Introduction 39 3. Fishes of the Ríos Tahuamanu, Manuripi and 14 Chapter Summaries Nareuda, Depto. Pando, Bolivia: Diversity, 16 Recommended Conservation and Distribution, Critical Habitats and Economic Research Activities Value Barry Chernoff, Philip W. Willink, Jaime 18 Resumen Ejecutivo Sarmiento, Soraya Barrera, Antonio Machado- Allison, Naércio Menezes, and Hernán Ortega 18 Introducción 19 Resumen de Capitulos 47 4. Diversity and Abundance of Fishes and 21 Actividades recomendadas para la Habitats in the Río Tahuamanu and Río Manuripi conservación e investigación Basins Antonio Machado-Allison, Jaime Sarmiento, Philip 23 Maps of the Río Orthon Basin, Pando, W. Willink, Naércio Menezes, Hernán Ortega, and Bolivia Soraya Barrera 25 Images of the AquaRAP Expedition 51 5. Geographic and Macrohabitat Partitioning of Fishes in the Tahuamanu-Manuripi Region, 26 Satellite Image of Upper Río Orthon Upper Río Orthon Basin, Bolivia Barry Chernoff, Philip W. Willink, Jaime Sarmiento Basin, Pando, Bolivia Antonio Machado-Allison, Naércio Menezes, and 27 Chapters Hernán Ortega 68 6. Landscape-Based Genetic Assessment of the Fishes of the Ríos Tahuamanu and Manuripi Basins, Bolivia Theresa M. Bert 4 CONSERVATION INTERNATIONAL Rapid Assessment Program 73 Glossary 84 4. Distribution of Chironomidae genera 75 Appendices identified from selected sites of the AquaRAP expedition to Pando, Bolivia in September 76 1. Summary of the physico-chemical 1996. characteristics of the waters in the Upper Francisco Antonio R. Barbosa, Fernando Villarte Tahuamanu and Lower Nareuda/Middle V., Juan Fernando Guerra Serrudo, Marcos Tahuamanu sub-basins during the Callisto Faria Pereira, and Juliana de Abreu AquaRAP expedition to Pando, Bolivia Vianna in September 1996. Francisco Antonio R. Barbosa, Fernando 85 5. Decapod crustaceans collected by the Villarte V., Juan Fernando Guerra Serrudo, AquaRAP expedition to Pando, Bolivia in Germana de Paula Castro Prates Renault, September 1996. Paulina María Maia-Barbosa, Rosa María Célio Magalhães Menéndez, Marcos Callisto Faria Pereira, and Juliana de Abreu Vianna 87 6. Fishes collected during the AquaRAP expedition to Pando, Bolivia in September 79 2. Distribution of zooplankton species 1996. along the sampling stations of the Jaime Sarmiento, Barry Chernoff, Soraya Barrera, AquaRAP expedition to Pando, Bolivia in Antonio Machado-Allison, Naércio Menezes, and September 1996. Hernán Ortega Francisco Antonio R. Barbosa, Fernando Villarte V., Juan Fernando Guerra Serrudo, Germana de Paula Castro Prates Renault, 96 7. Comparative list of fishes reported from the Paulina María Maia-Barbosa, Rosa María Bolivian Amazon. Menéndez, Marcos Callisto Faria Pereira, and Philip W. Willink, Jaime Sarmiento, and Barry Juliana de Abreu Vianna Chernoff 83 3. Composition of the benthic 114