Faculty of Bioscience Engineering Academic year 2013 – 2014 Ecological assessment of the Guayas river basin in Ecuador Natalija Semjonova Promotor: Prof. dr. ir. Peter Goethals Tutor: Nguyen Thi Hanh Tien Ir. Gert Everaert Ir. Elina Bennetsen Master’s dissertation submitted in partial fulfillment of the requirements for the degree of Master of Environmental Sanitation PREFACE Work on the thesis was feasible with the effort of several people to whom I would like to dedicate the following words. First of all, I would like to express my gratitude to Prof. Peter Goethals for the remarkable opportunity to participate in the research project of ecological assessment of the Guayas river basin in Ecuador. Also, I would like to thank Nguyen Thi Hanh Tien, who led me through the field-work and sampling practices, and particularly Gert Everaert and Elina Bennetsen for their great assistance, patience and all the knowledge I gained as a result of working with them. i ABSTRACT In this dissertation the physical-chemical and ecological status of the Guayas river basin in Ecuador and its relation to alterations caused by human activities were studied. Physical-chemical and biological (macroinvertebrates) samples were taken at 120 locations in the Guayas river basin. At each sampling location hydro-morphological conditions were recorded by means of field protocols. Prior to the actual data analysis, data were explored to identify outliers and correlated variables. Next, generalized linear models (GLMs) were used to relate the ecological water quality (quantified as the biological monitoring working party (BMWP)) with the environmental variables that were measured. A threshold indicator taxa analysis (TITAN) was used to identify community composition shifts along environmental gradients. The GLM successfully predicted the low BMWP ranges (poor to moderate ecological status). It was found that the BMWP strongly depended on the nutrient status, the landuse type (forests, arable lands, pastures and urban areas) and the altitude where the samples were taken. The most representative gradients in the TITAN analysis were dissolved oxygen, turbidity, velocity, distance to mouth, elevation and hydro-morphological coordinate gradient as these variables showed clear changes in community abundance and diversity change along the measured gradient. Furthermore, we found that the macroinvertebrate community in the stagnant water of the Peripa reservoir was different from the communities in the rivers upstream and downstream from the reservoir. These results suggest that in future research the Guayas river basin should be differentiated into at least three independent aquatic systems: source streams, reservoir and lowland streams. ii TABLE OF CONTENTS PREFACE............................................................................................................................. i ABSTRACT ........................................................................................................................ ii TABLE OF CONTENTS ................................................................................................... iii LIST OF TABLES .............................................................................................................. v LIST OF FIGURES ............................................................................................................ vi LIST OF ABBREVIATIONS ............................................................................................ ix CHAPTER 1: INTRODUCTION........................................................................................ 1 CHAPTER 2: LITERATURE REVIEW............................................................................. 2 2.1.Water quality.............................................................................................................. 2 2.1.1. Eutrophication and organic matter ..................................................................... 3 2.1.2. Toxic substances and poisons ............................................................................ 4 2.1.3. Engineering impacts on flow regime ................................................................. 8 2.1.4. Other abiotic factors ........................................................................................... 9 2.2. Water quality assessment .......................................................................................... 9 2.2.1. Physical-chemical assessment .......................................................................... 10 2.2.2. Ecological assessment ...................................................................................... 10 2.2.3. Hydro-morphological assessment .................................................................... 11 2.3. Ecological metrics and multimetric indices ............................................................ 11 2.3.1. Biological monitoring working party (BMWP) ............................................... 12 2.3.2. Ecological quality ratio (EQR) ......................................................................... 13 2.4. Ecological data analysis .......................................................................................... 13 2.5. Problem statement and research question ............................................................... 15 CHAPTER 3: MATERIALS AND METHODS ............................................................... 16 3.1. Description of study area ........................................................................................ 16 3.1.1. Geographical information ................................................................................ 16 3.1.2. Landuse ............................................................................................................ 16 3.1.3. Climate ............................................................................................................. 17 3.2. Data collection ........................................................................................................ 18 3.2.1. Physical-chemical variables ............................................................................. 18 3.2.2. Macroinvertebrates ........................................................................................... 18 iii 3.2.3. Hydro-morphological variables ....................................................................... 20 3.3. Statistical analysis ................................................................................................... 20 3.3.1. Removal of undisputed values ......................................................................... 21 3.3.2. Data exploration ............................................................................................... 21 3.4. Statistical modeling................................................................................................. 23 3.4.1. Predictive modeling ......................................................................................... 23 3.4.2. Threshold Indicator Taxa ANalysis (TITAN) .................................................. 24 3.5. Ordination analysis of hydro-morphological variables .......................................... 26 3.6. R software ............................................................................................................... 27 CHAPTER 4: RESULTS .................................................................................................. 28 4.1. Data exploration ...................................................................................................... 28 4.1.1. Outliers ............................................................................................................. 28 4.1.2. Collinearity ....................................................................................................... 31 4.2. BMWP correlation with physical-chemical and hydro-morphological variables .. 35 4.3. GLM........................................................................................................................ 40 4.4. TITAN .................................................................................................................... 46 4.5. PCOA ...................................................................................................................... 60 4.6. Titan analysis with hydro-morphological variable gradient as coordinate vector .. 67 CHAPTER 5: DISCUSSION ............................................................................................ 69 5.1. Objective of the study ............................................................................................. 69 5.2. Ecological status prediction .................................................................................... 69 5.3. Representative gradients and macroinvertebrate community variation .................. 70 5.4. Elevation and landuse influence on macroinvertebrate community ....................... 72 5.5. Clusters of macroinvertebrate communities ........................................................... 74 5.6. Influence of water hyacinth on reservoir ecosystem .............................................. 75 CHAPTER 6: CONCLUSION .......................................................................................... 77 LIST OF REFERENCES .................................................................................................. 80 iv LIST OF TABLES Table 2.1 BMWP score categories (Mahazar et al., 2013) ..............................................