A survey of the metazoan parasite assemblage of snoek, Thyrsites atun (Euphrasen, 1791), off South Africa with an assessment of host-parasite relationships and potential biological tags Muhammad Azher Irfan Nunkoo Dissertation submitted in fulfillment of the requirements for the degree of MASTER OF SCIENCE Marine Research Institute, Department of Biological Sciences University of Cape Town February 2015 University of Cape Town Supervisors: Dr. Cecile. C. Reed 1, Dr Sven. E. Kerwath 1, 2 1 Marine Research Institute, Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa 2 Fisheries Research and Development, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Roggebaai, 8012, Cape Town, South Africa The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgement of the source. The thesis is to be used for private study or non- commercial research purposes only. Published by the University of Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. University of Cape Town Plagiarism Declaration I know that plagiarism is wrong. Plagiarism is to use another’s work and to pretend that it is one’s own. I have used the Harvard convention for citation and referencing. Each contribution to and quotation in this project from the works of other people has been attributed, and has been cited and referenced. This project is my own work. I have not allowed, and will not allow, anyone to copy my work with the intention of passing it off as his or her own work. I acknowledge that copying someone else’s work, or part of it, is wrong and I declare that this is my own work. M. A. Irfan Nunkoo 05 February 2015 ii Table of Contents Abstract .................................................................................................................................... vi Acknowledgements ................................................................................................................. viii Introduction ................................................................................................................................1 1.1: Parasites, Humans and Nature ..........................................................................................1 1.2: The Parasitic Lifestyle ......................................................................................................2 1.3: The Diversity and Biogeography of Parasites ...................................................................2 1.3.1: The Diversity of Parasites ..........................................................................................2 1.3.2: The Origins of Parasite Diversity ...............................................................................3 1.3.3: The Theory of Parasite Diversity ...............................................................................4 1.3.4: The Biogeography of Marine Parasites ......................................................................5 1.4: The Ecological Significance and Consequences of Parasitism ...........................................7 1.4.1: The Ecological Significance of Parasites ....................................................................8 1.4.2: Economic and Health Impacts of Fish Parasites .........................................................9 1.5: Parasitology, Fisheries Biology and Environmental Monitoring ...................................... 10 1.5.1: Parasites as Biological Tags ..................................................................................... 10 1.5.2: Parasites as Bioindicators......................................................................................... 12 1.6: Marine Parasitology in South Africa ............................................................................... 13 1.7: Thyrsites atun ................................................................................................................. 14 1.7.1: The Cape Snoek ....................................................................................................... 15 1.7.2: Parasites of Thyrsites atun: what do we know? ........................................................ 16 1.8: Objectives of this Dissertation ........................................................................................ 17 Materials and Methods .............................................................................................................. 19 2.1: Study Area ..................................................................................................................... 19 2.2: Sampling of Host Population .......................................................................................... 19 2.3: Processing Samples ........................................................................................................ 20 iii 2.3.1: Host dissection and data collection .......................................................................... 20 2.3.2: Preservation and identification of parasites .............................................................. 23 2.4: Statistical Analyses......................................................................................................... 25 2.4.1: Exploratory data analysis ......................................................................................... 25 2.4.2: The hosts’ characteristics ......................................................................................... 26 2.4.3: Determinants of Parasite Infestation ......................................................................... 28 2.4.4: Parasite community structure ................................................................................... 32 Results ...................................................................................................................................... 34 3.1: Exploratory Data Analysis .............................................................................................. 34 3.2: Host Sample Characteristics ........................................................................................... 34 3.3: Parasite Assemblage ....................................................................................................... 40 3.4: Determinants of Infection ............................................................................................... 42 3.4.1: Anisakis spp. ............................................................................................................ 42 3.4.2: Molicola uncinatus .................................................................................................. 44 3.4.3: Hepatoxylon trichiuri ............................................................................................... 49 3.4.4: Tentacularia coryphaenae ....................................................................................... 52 3.4.5: Nothobomolochus fradei .......................................................................................... 55 3.4.6: Hatschekia conifera ................................................................................................. 59 3.4.7: Caligus dakari ......................................................................................................... 64 3.4.8: Caligus zei ............................................................................................................... 67 3.4.9: Corynosoma australe ............................................................................................... 68 3.4.10: Digenea sp. ............................................................................................................ 70 3.5: Community Analysis ...................................................................................................... 73 Discussion ................................................................................................................................. 77 4.1: The Host Sample’s Characteristics ................................................................................. 77 4.2: The Host-Parasite Relationships of Snoek ...................................................................... 78 iv 4.2.1: Nematoda ................................................................................................................ 78 4.2.2: Myxozoa.................................................................................................................. 81 4.2.3: Cestoda .................................................................................................................... 83 4.2.4: Copepoda ................................................................................................................ 86 4.2.5: Acanthocephala ....................................................................................................... 92 4.2.6: Digenea ................................................................................................................... 95 4.3: Parasite Community Structure ........................................................................................ 96 4.4: Population Structure and Biological Tags ....................................................................... 98 4.5: Recommendations and Conclusions .............................................................................. 100 4.5.1: Constraints & Future research ................................................................................ 100 4.5.2: