RISK ANALYSIS AND POTE NTIAL TRANSMISSION AND IMPLICATIONS OF EXOTIC GYRODACTYLUS SPECIES ON CULTURED AND WILD CYPRINIDS IN THE WESTERN CAPE, SOUTH AFRICA By: Monique Rochelle Maseng Submitted in fulfillment of the requirements for the degree of Magister Scientiae Department of Biodiversity and Conservation Biology Faculty of Natural Sciences University of the Western Cape Bellville Supervisors: Dr Kevin Christison (Department of Biodiversity and Conservation, University of the Western Cape) Prof Charles Griffiths (Zoology Department, University of Cape Town) September 2010 Declaration I declare that this is my own work, that Risk analysis and potential implications of exotic Gyrodactylus species on cultured and wild cyprinids in the Western Cape, South Africa has not been submitted for any degree or examination in any other university, and that all the sources I have used or quoted have been indicated and acknowledged by complete references. ………………………………… Monique Rochelle Maseng September 2010 i Keywords Challenge infections Gyrodactylus Gyrodactylus burchelli Host specificity Morphological variation Phenotypic plasticity Pseudobarbus sp. Risk analysis ii Abstract The expansion of the South African aquaculture industry coupled with the lack of effective parasite management strategies may potentially have negative effects on both the freshwater biodiversity and economics of the aquaculture sector. Koi and goldfish are notorious for the propagation of parasites worldwide, some of which have already infected indigenous fish in South Africa. Koi and goldfish have been released into rivers in South Africa since the 1800’s for food and sport fish and have since spread extensively. These fish are present in most of the river systems in South Africa and pose an additional threat the indigenous cyprinids in the Western Cape. Monogenean parasites of the genus Gyrodactylus are of particular concern, as their unique biology renders them a possible threat. Gyrodactylus kherulensis and G. kobayashii were identified from koi and goldfish respectively imported from Asia, Europe and locally bred fish. Morphometrics and the use of statistical classifiers, which includes univariate (ANOVA and Kruskal-Wallis), bivariate (Pearson’s correlation) and multivariate (Principal Component Analysis) placed the two species within their respective groups. There was some intraspecific variation among the different populations collected from the various locations, especially in the hamulus and ventral bar features, but the marginal hooklets, however, remained static for both helminth species. This illustrates again the importance of the minor variations in the marginal hook features in gyrodactylid taxonomy. Infection trials conducted by co-habitation of infected koi and goldfish with two indigenous redfin minnow species, Pseudobarbus burchelli and P. phlegethon showed that both G. kherulensis and G. kobayashii could successfully transfer and establish themselves on P. phlegethon, where the infection increased rapidly initially, but remained relatively constant thereafter. P. burchelli appeared to be inherently resistant as the parasite population growth rate initially remained steady, until the infection died off. The wild-caught indigenous iii fish were however not infected with any exotic Gyrodactylus species, but a new species, G. burchelli n. sp. described from the body surfaces of P. burchelli. This dissertation is dedicated to my mother, Sylvia Sophia Maseng, for all her support and encouragement through the entirety of the project. iv Acknowledgements I would like to extend my heartfelt gratitude to God who has been with me throughout the journey and who has aided me in my requests. Thank You Lord, I couldn’t have finished this without You. My family has been my pillar of strength and supported me through all times. Thank you, so much. I would also like to thank my friends and former class mates also for their support, especially Riaan Cedras. Also to Sean Marr, who helped me with the wild sampling, you have played an instrumental role in my project, thanks a million. To Martin Hendricks for technical support, and who never hesistated to help at any time, thank you so much. I’d also like to thank my supervisor Dr Kevin Christison and co-supervisor Prof Charles Griffiths for supplying me with the needed tools and knowledge to complete my project. Finally I’d like to thank the Centre for Invasion Biology for their financial support, I am eternally grateful. v Table of Contents Declaration................................................................................................................ i Keywords .................................................................................................................. ii Abstract ..................................................................................................................... iii Dedication ................................................................................................................. iv Acknowledgements .................................................................................................. v Chapter 1: Introduction ............................................................................................ 1 Chapter 2: First records of Gyrodactylus kherulensis Ergens 1974 from Cyprinus carpio koi L. and of Gyrodactylus kobayashii Hukuda, 1940 from Carassius auratus L. in South Africa: A morphological comparison of populations of various geographic origins imported into South Africa. Abstract ...................................................................................................................... 20 Introduction ................................................................................................................ 21 Materials and Methods ............................................................................................... 26 Results ........................................................................................................................ 30 Discussion .................................................................................................................. 61 References .................................................................................................................. 65 vi Chapter 3: Challenge Infections with the exotic monogeneans, Gyrodactylus kherulensis Ergens (1974) and G. kobayashii Hukuda (1940), on two indigenous redfin minnows in the Western Cape, South Africa: A preliminary study. Abstract ...................................................................................................................... 69 Introduction ................................................................................................................ 69 Materials and Methods ............................................................................................... 73 Results ....................................................................................................................... 76 Discussion ................................................................................................................. 84 References ................................................................................................................. 87 Chapter 4: Gyrodactylus burchelli n. sp. from the redfin minnow, Pseudobarbus burchelli Smith, 1841 (Pisces, Cyprinidae). Abstract ...................................................................................................................... 90 Introduction ................................................................................................................ 90 Materials and Methods ............................................................................................... 92 Results ........................................................................................................................ 93 Discussion ................................................................................................................. 98 References .................................................................................................................. 103 vii Chapter 5: Risk Analysis of Gyrodactylus kherulensis Ergens 1974 from Cyprinus carpio koi L. and Gyrodactylus kobayashii Hukuda, 1940 from Carassius auratus L. imported into South Africa: Discussion. Abstract ...................................................................................................................... 105 Introduction ................................................................................................................ 106 Conclusion ................................................................................................................. 124 References .................................................................................................................. 125 Chapter 6: References References .................................................................................................................. 129 Appendix ................................................................................................................... 140 viii Chapter 1 Introduction and background Aquaculture and its socio-economic and ecological implications The worldwide aquaculture industry, for both edible and ornamental species, has increased exponentially over the past 30 years and is predicted to continue growing (Thoney and Hargis 1991) at about 10% per annum, primarily to provide for the needs of a growing human