Vulnerability and adaptability of Africa’s inland fisheries to climate change: An interdisciplinary approach to a multi-dimensional conservation challenge Elizabeth A. Nyboer Department of Biology McGill University, Montreal September, 2018 A thesis submitted to McGill University in partial fulfillment of the requirements of the degree of Doctor of Philosophy. ©Elizabeth A. Nyboer, 2018 1 Contents Abstract viii Résumé x Preface xii Thesis format xii Contribution of authors xiii Statement of originality xiv Ethics statement xvi Acknowledgements xvii Introduction 1 Effects of climate change on inland aquatic ecosystems 2 Temperature effects on fishes 3 Fish metabolism and temperature 5 Climate change in tropical ectotherms 8 Climate change and African fisheries 8 Thesis structure 9 References 11 Chapter 1: Assessing the vulnerability of Africa’s freshwater fishes to climate change: a continent-wide trait-based analysis 23 1.1 Abstract 24 1.2 Introduction 25 1.2.1 Climate change vulnerability assessments 25 1.2.2 Vulnerability of inland waters to climate change 26 1.2.3 African freshwater fishes – Integration of climate change into conservation needs 27 1.3 Methods 28 1.3.1 Fish species selection 28 1.3.2 Assessing climate change vulnerability: overview 29 1.3.3 Data collection 29 1.3.3.1 Trait data 29 1.3.3.2 Distribution data 30 1.3.4 Defining vulnerability dimensions 30 1.3.4.1 Sensitivity and low adaptive capacity dimensions 30 1.3.4.2 Exposure dimension 31 1.3.5 Assigning climate change vulnerability scores 32 1.3.6 Assigning conservation value scores 34 1.3.7 Mapping areas of greatest concentration of vulnerable species 34 1.3.8 Trait and family analysis 35 1.4 Results 36 1.4.1 Data availability and quality 36 1.4.2 Summary of vulnerability dimensions 36 1.4.3 Summary of climate change vulnerability 38 1.4.3.1 Vulnerable regions 38 i 1.4.3.2 Vulnerable families 39 1.4.4 Summary of conservation value 39 1.4.4.1 Regions and families of high conservation value 40 1.4.5 Comparison of vulnerability and conservation value 40 1.5 Discussion 41 1.5.1 Vulnerable species and families 42 1.5.2 Species traits that contributed to vulnerability 42 1.5.3 Other environmental stressors 44 1.5.4 Identifying research needs 45 1.5.5 Conservation planning 45 1.5.5.1 Comparison of climate vulnerability to traditional conservation value metrics 46 1.5.5.2 Contribution to conservation management 47 1.6 Conclusion 48 1.7 References 49 1.8 Tables 55 Table 1.1 - Description of trait sets, variables and thresholds qualifying species and high or low for vulnerability and conservation value. 55 Table 1.2 - Numbers and proportions of species within families that are vulnerable and of high conservation value. 59 1.9 Figures 60 Figure 1.1 - Map showing ichthyological provinces, main water bodies, and species richness of freshwater fish species. 60 Figure 1.2 - Numbers of species in each climate change vulnerability category and conservation value under optimistic and pessimistic scenarios. 61 Figure 1.3 - Bivariate map showing overlap in biological susceptibility and exposure. 62 Figure 1.4 - Univariate map of conservation value and bivariate map of vulnerability and conservation value. 63 Figure 1.4 - Numbers of species qualifying as highly vulnerable due to a single trait within each vulnerability dimension, and conservation value. 64 Preface to Chapter 2 65 Chapter 2: Elevated temperature and acclimation time affect metabolic performance in the heavily exploited Nile perch of Lake Victoria 66 2.1 Abstract 67 2.2 List of abbreviations 68 2.3 Introduction 69 2.4 Methods 72 2.4.1 Fish collection and holding 72 2.4.1.1. 3-week acclimation trials 72 2.4.1.2 Acute exposure trials 73 2.4.2 Critical thermal maximum (CTmax) protocol 74 2.4.3 Respirometry set-up 74 2.4.4 Respirometry protocol 75 2.4.4.1 Time validation for Nile perch 75 2.4.4.2 Respirometry trials 76 2.4.4.3 Calculations of metabolic traits 76 2.4.5 Growth and condition 77 2.4.6 Statistical analyses 79 2.5 Results 79 2.5.1 Critical thermal maxima 79 ii 2.5.2 Metabolic traits: SMR, MMR, AS, EPOC, RT 80 2.5.3 Growth and condition 81 2.6 Discussion 81 2.6.1 Critical thermal maximum is affected by temperature and exposure time 82 2.6.2 Metabolic variables are affected by temperature 83 2.6.3 Metabolic variables are affected by exposure time 84 2.6.4 Other performance measures provide insight 85 2.6.5 Implications for climate change 87 2.7 Conclusions 88 2.8 References 89 2.9 Tables 95 Table 2.1 - Sample sizes and body size of acclimated fish. 95 Table 2.2 - ANCOVA results for CTmax, metabolic traits, and fitness-related traits across experimental temperature within each acclimation time. 96 Table 2.3 - ANCOVA results for the effects of experimental temperature, exposure time, and their interaction for CTmax, metabolic traits, and fitness-related traits. 97 Table 2.4 - Pearson’s correlations of body mass with metabolic traits. 98 2.10 Figures 99 Figure 2.1 - Critical thermal maxima for Nile perch across acclimation time and experimental temperature. 99 Figure 2.2 - Linear relationships between log body mass and log SMR, MMR and AS. 100 Figure 2.3 - Results of ANCOVA testing aerobic metabolic performance of juvenile Nile perch over a range of experimental temperatures. 101 Figure 2.4 - Results of ANCOVA comparing aerobic metabolic performance among acutely exposed and thermally acclimated Nile perch over a range of temperatures. 102 Figure 2.5 - Changes in condition and growth across experimental temperatures. 103 Preface to Chapter 3 104 Chapter 3: Cardiac plasticity influences aerobic performance and thermal tolerance in a tropical, freshwater fish at elevated temperatures 105 3.1 Abstract 106 3.2 List of abbreviations 107 3.3 Introduction 108 3.4 Methods 112 3.4.1 Overview 112 3.4.2 Fish collection and rearing 113 3.4.3 Laboratory experiments 115 3.4.3.1 Metabolic traits 115 3.4.3.2 Critical thermal maximum 116 3.4.4 Calculations of metabolic traits 117 3.4.5 Body size, condition, and organ measurements 117 3.4.6 Statistical analysis 119 3.5 Results 121 3.5.1 Body size and condition 121 3.5.2 Metabolic traits and critical thermal maximum 121 3.5.3 Organ development and plasticity 122 3.6 Discussion 123 3.6.1 Developmental plasticity in upper thermal tolerance and metabolic traits 124 3.6.2 Responses of organ traits 126 iii 3.6.3 Cardiac plasticity affects thermal tolerance and metabolic function 128 3.7 References 131 3.8 Tables 137 Table 3.1 - ANOVA results of tank water quality variables. 137 Table 3.2 - Sample sizes and means of body mass, standard length, total length, and condition of juvenile Nile perch in experiments. 138 Table 3.3 - ANVOA results of differences in body size and organ traits across rearing temperatures. 139 Table 3.4 - ANOVA results of effects of rearing temperature and experimental temperature on CTmax and metabolic traits. 140 Table 3.5 - ANCOVA reuslts of the influence of cardiac traits on thermal tolerance and metabolic performance of Nile perch from different rearing temperatures. 141 Table 3.6 - ANOVA results testing the effects of rearing temperature on a series of gill traits. 142 3.9 Figures 143 Figure 3.1 - Illustrations depicting morphology and dissection points for Nile perch organs. 143 Figure 3.2 - Results of ANOVA examining the effects of rearing regime on fitness-related traits and organ traits. 144 Figure 3.3 - ANOVAS results comparing metabolic traits and thermal tolerance limits in Nile perch among experimental temperatures and between rearing temperatures. 145 Figure 3.4 - Linear relationships between metabolic traits and heart traits. 146 Preface to Chapter 4 147 Chapter 4: Assessing the vulnerability and adaptive capacity of fishing communities to climate change in the Lake Victoria basin of East Africa 148 4.1 Abstract 149 4.2 Introduction 150 4.2.1 Theoretical framework 150 4.2.2 Research context: History and social-ecological changes in the Lake Victoria basin 152 4.3 Methods 155 4.3.1 Site selection 155 4.3.2 Research approach 157 4.3.2.1 Survey methods 157 4.3.2.2 Survey analysis 158 4.3.2.3 Focus groups and key informant interview methods 159 4.4 Results 160 4.4.1 Differences among landing sites, involvement types, and between genders 160 4.4.2 Relationships among indices 162 4.4.3 Perceptions of climate change, and impacts on livelihoods 162 4.4.4 Diversification options, adaptive strategies, and coping with climate change 163 4.4.4.1 Diversification 163 4.4.4.2 Adaptive strategies and outcomes 164 4.4.4.3 Coping strategies 166 4.4.5 Barriers to diversification 166 4.5 Discussion 166 4.5.1 Perceptions of environmental change 167 4.5.2 Climate change narrows the walls of social-ecological traps 168 4.5.3 Developing capacity for livelihood diversification 171 4.5.4 Building social capital 173 4.5.5 Using traditional knowledge to inform fishery sustainability 174 4.5.6 Promoting community agency through improved governance 175 iv 4.6 Conclusions 177 4.7 References 178 4.8 Tables 186 Table 4.1 - Landing site characteristics and respondent demographics from surveys. 186 Table 4.2 - Description and definitions of indices calculated from household surveys. 187 Table 4.3 - Number of participants and groupings for focus groups discussions.