A HISTOLOGY-BASED HEALTH ASSESSMENT OF SELECTED FISH SPECIES FROM TWO RIVERS IN THE KRUGER NATIONAL PARK BY WARREN CLIFFORD SMITH DISSERTATION SUBMITTED IN FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE MAGISTER SCIENTIAE IN AQUATIC HEALTH IN THE FACULTY OF SCIENCE AT THE UNIVERSITY OF JOHANNESBURG SUPERVISOR: DR. G.M. WAGENAAR CO-SUPERVISOR: PROF. N.J. SMIT MAY 2012 Contents Acknowledgements _______________________________________________________ 6 Abstract ________________________________________________________________ 8 List of abbreviations _____________________________________________________ 11 List of figures ___________________________________________________________ 14 List of Tables ___________________________________________________________ 17 Chapter 1: General Introduction ____________________________________________ 19 1.1 Introduction _______________________________________________________ 19 1.2 Study motivation ___________________________________________________ 19 1.3 Hypotheses ________________________________________________________ 21 1.4 Aim of the study ____________________________________________________ 21 1.5 Objectives _________________________________________________________ 21 1.6 Dissertation outline _________________________________________________ 21 Chapter 2: Literature Review ______________________________________________ 23 2.1 Introduction _______________________________________________________ 23 2.2 Study Sites ________________________________________________________ 23 2.2.1 Olifants River (OR) _______________________________________________ 23 2.2.2 Luvuvhu River (LR) _______________________________________________ 25 2.3 Metals in the aquatic environment _____________________________________ 26 2.3.1 Aluminium (Al) ___________________________________________________ 26 2.3.2 Arsenic (As) _____________________________________________________ 27 2.3.3 Cadmium (Cd) ___________________________________________________ 28 2.3.4 Chromium (Cr) ___________________________________________________ 29 2.3.5 Copper (Cu) _____________________________________________________ 30 2.3.6 Iron (Fe) ________________________________________________________ 31 2.3.7 Lead (Pb) _______________________________________________________ 31 2.3.8 Manganese (Mn) _________________________________________________ 32 [1] 2.3.9 Zinc (Zn) _______________________________________________________ 33 2.4 Study organisms ___________________________________________________ 34 2.4.1 Hydrocynus vittatus _______________________________________________ 34 2.4.2 Labeobarbus marequensis _________________________________________ 35 2.4.3 Labeo cylindricus _________________________________________________ 37 2.4.4 Labeo rosae _____________________________________________________ 38 2.5 Health Assessment Index ____________________________________________ 39 2.6 Blood constituents’ analysis __________________________________________ 39 2.7 Biometric indices ___________________________________________________ 40 2.7.1 Condition factor __________________________________________________ 40 2.7.2 Hepatosomatic index ______________________________________________ 40 2.7.3 Splenosomatic index ______________________________________________ 40 2.7.4 Gonadosomatic index _____________________________________________ 41 2.8 Histology and histopathology of selected target organs ___________________ 41 2.8.1 Liver as a target organ _____________________________________________ 41 2.8.2 Kidney as a target organ ___________________________________________ 43 2.8.3 Gill as a target organ ______________________________________________ 46 2.8.4 Testis as a target organ ____________________________________________ 52 2.8.5 Ovary as a target organ ____________________________________________ 53 2.8.6 Semi-quantitative histological assessment _____________________________ 54 2.9 Ageing ____________________________________________________________ 54 Chapter 3: Materials and Methods __________________________________________ 56 3.1 Introduction _______________________________________________________ 56 3.2 Study period _______________________________________________________ 56 3.3 Water and sediment collection ________________________________________ 60 3.4 Physical water quality parameters _____________________________________ 60 3.5 Field surveys ______________________________________________________ 61 3.6 Histology-based health assessment protocol ____________________________ 64 3.6.1 Blood constituents analysis _________________________________________ 64 3.6.2 Necropsy _______________________________________________________ 64 3.6.3 HAI ____________________________________________________________ 64 [2] 3.6.4 Biometric indices _________________________________________________ 64 3.7 Tissue processing __________________________________________________ 65 3.8 Qualitative histological assessment ___________________________________ 67 3.8.1 Gonadal reproductive stage determination: _____________________________ 67 3.9 Semi-quantitative histological assessment ______________________________ 69 3.10 Ageing ___________________________________________________________ 72 3.11 Statistical analysis _________________________________________________ 73 Chapter 4: Results _______________________________________________________ 74 4.1 Introduction _______________________________________________________ 74 4.2 Physical water quality parameters _____________________________________ 74 4.2.1 Temperature ______________________________________________________ 74 4.2.2 pH ____________________________________________________________ 74 4.2.3 Oxygen percentage _______________________________________________ 74 4.2.4 Conductivity _____________________________________________________ 74 4.2.5 Total dissolved salts ______________________________________________ 75 4.3 Metal concentrations ________________________________________________ 75 4.3.1 Water metal concentrations _________________________________________ 75 4.3.2 Sediment metal concentrations ______________________________________ 77 4.4 Biometric indices ___________________________________________________ 78 4.4.1 Condition factor (Cf) _______________________________________________ 78 4.4.2 Hepatosomatic index (HSI) _________________________________________ 78 4.4.3 Splenosomatic index (SSI) _________________________________________ 78 4.4.4 Male Gonadosomatic index (GSI) ____________________________________ 79 4.4.5 Female Gonadosomatic index (GSI) __________________________________ 79 4.5 Blood parameters ___________________________________________________ 79 4.5.1 Haematocrit (Hct) _________________________________________________ 79 4.5.2 Leukocrit (Lct) ___________________________________________________ 80 4.5.3 Total plasma protein (TP) __________________________________________ 81 4.6 Health assessment index ____________________________________________ 83 4.7 Normal histology ___________________________________________________ 85 4.7.1 Normal liver histology _____________________________________________ 85 [3] 4.7.2 Normal kidney tissue ______________________________________________ 88 4.7.3 Normal gill tissue _________________________________________________ 91 4.7.4 Normal testis tissue _______________________________________________ 93 4.7.5 Normal ovary tissue _______________________________________________ 96 4.8 Gonadal staging ____________________________________________________ 99 4.8.1 Testis staging ____________________________________________________ 99 4.8.2 Ovary staging ____________________________________________________ 99 4.9 Histopathology _____________________________________________________ 99 4.9.1 Liver histopathology ______________________________________________ 100 4.9.2 Kidney histopathology ____________________________________________ 104 4.9.3 Gill histopathology _______________________________________________ 108 4.9.4 Testis histopathology _____________________________________________ 109 4.9.5 Ovary histopathology _____________________________________________ 111 4.9.6 Fish index _____________________________________________________ 113 4.10 Age _____________________________________________________________ 115 4.11 Age – Histopathology correlations ___________________________________ 118 4.11.1 Age – Liver Index Correlations ____________________________________ 118 4.11.2 Age – Fish Index Correlations _____________________________________ 118 Chapter 5: Discussion ___________________________________________________ 121 5.1 Introduction ______________________________________________________ 121 5.2 Physical water quality parameters ____________________________________ 121 5.2.1 Temperature ___________________________________________________ 121 5.2.2 pH ___________________________________________________________ 121 5.2.3 Dissolved oxygen ________________________________________________ 122 5.2.4 TDS/Conductivity ________________________________________________ 122 5.3 Metal concentrations in water and sediment ____________________________ 122 5.4 Biometric indices __________________________________________________ 125 5.4.1 Condition factor (Cf) ______________________________________________ 125 5.4.2 Hepatosomatic index (HSI) ________________________________________ 126 5.4.3 Splenosomatic index (SSI) ________________________________________ 126 5.4.4 Gonadosomatic index (GSI) _______________________________________ 126 5.5 Blood parameters __________________________________________________