Aspects of the biology of Ergasilus sarsi a gill ectoparasite of Lamprichthys tanganicanus from Lake Tanganyika. By ESMARI KILIAN DISSERTATION Submitted in fulfilment of the requirements for the degree MASTER OF SCIENCE In ZOOLOGY in the FACULTY OF SCIENCE at the UNIVERSITY OF JOHANNESBURG SUPERVISOR: PROF. A. AVENANT-OLDEWAGE October 2012 i ACKNOWLEDGEMENTS I would like to acknowledge the following people: - Professor A. Avenant- Oldewage for her support and guidance during the study. - The National Research Foundation (NRF) and the University of Johannesburg for funding the study. - Tannie Edie Lutch for all her help during the practical part of my study. - Mr. Ebrahim Karim of the Graphic department of the University of Johannesburg for the making of photo plates. - My family and friends for emotional support and encouragement to succeed. ii ABSTRACT A literature survey revealed gaps in the knowledge on Ergasilus in Africa. This studied aimed to elucidate on some of these matters. Ergasilus sarsi was collected from Lamprichthys tanganicanus during an expedition to Lake Tanganyika in March 2010. The gills of the fish were removed and preserved for further studies. Preserved specimens were studied with dissection- and light microscopy. Some specimens were also studied with a scanning electron microscope (SEM). For light microscopy the specimens were sectioned and then stained with AZAN and H&E. A total of 32 Lamprichthys tanganicanus were collected and studied for ergasilids. The prevalence was 86.40%, the mean intensity 7.56 and the mean abundance 6.38. A total of 204 parasites were collected and only 27 hosts were infected. The highest intensity was 29 parasites. Pearson’s Chi-squared test was used to compare attachment preferences of Ergasilus sarsi. The parasite exhibited site selection but not host specificity. It was noticed that E. sarsi mostly attach to the tip of the gill filament of the second gill arch. The second gill arch receives the largest portion of water flow supporting distribution of newly hatch ergasilid nauplius. There was no significant preference for the dorsal, medial and ventral attachment sites (p-value = 0.000542). However, significant preference between distal, central and proximal regions (p-value = 1.19) was observed. Fryer (1965) observed that the pathology caused by ergasilids is related to their attachment position on the host. Ergasilids display variation regarding morphology of their second antennae. Some have spines and others elongated antennae that wraps around the entire gill filament. This study shows that Ergasilus sarsi (with no spines on the second antennae) wraps around the gill filament and cause considerable damage to the host. The entire gill filament structure changed due to lamellar fusion and proliferation of mucous – and epithelial cells. Comparison of an infected gill to a healthy gill revealed differences. The compression caused by the second antennae caused some blood vessels to rupture resulting in haemorrhage. The swimming legs of the parasite also cause considerable damage by scraping gill tissue off the host and pushing it towards the mouth parts of the parasite. Mucous cells, gill epithelium and blood cells were observed in the vicinity of the mouth and in the intestine of the parasite. An increase in the number of Rodlet cells and mast cells were also observed on the gills in close proximity to the parasite. Increase in the number of these cells clearly indicate an inflammatory response. iii This is the first record of Ergasilus sarsi on Lamprichthys tanganicanus. This study also provides the first detailed description of the pathology caused by Ergasilus sarsi as well as the attachment distribution of this parasite. The shortcomings of the study and future study areas are discussed in the last chapter. iv OPSOMMING ‘n Literatuur oorsig het gapings in die kennis oor Ergasilus in Afrika bloot gelê. Hierdie studie het probeer om van die gapings te vul. Ergasilus sarsi is gevind op Lamprichthys tanganicanus tydens ‘n ekspedisie na Tanganjika- meer in Maart 2010. Die kieue van die vis was verwyder en fikseer vir verdere studies. Eksemplare was bestudeer met behulp van disseksie- en ligmikroskopie. Sommige eksemplare was ook bestudeer met ‘n skandeerelektronmikroskoop (SEM). Eksemplare vir ligmikroskopie was in hars ingebed en seriesneë is gemaak. Sneë was gekleur met AZAN en H&E. ‘n Totaal van 32 Lamprichthys tanganicanus is versamel en ondersoek vir verteenwoordigers van die Ergasilidae en daar is gevind dit is besmet met Ergasilus sarsi. Die persentasie besmetting was 86.40%, die gemiddelde besmettingsintensiteit was 7.56 en die besmettingsmoontlikheid was 6.38. ‘n Totaal van 204 parasiete was versamel en 27 gashere was besmet. Die hoogste besmettingsintensiteit was 29 parasiete. Pearson se Chi- kwadraat-toets was gebruik om vashegtings voorkeure van Ergasilus sarsi te vergelyk. Die parasiet toon ‘n voorkeur vir die vashegtings area maar nie vir die gasheer spesie nie. Ergasilus sarsi heg meestal aan die punte van die kieu-filamente van die tweede kieuboog vas. Die tweede kieuboog ontvang die grootste porsie van watervloei wat waarskynlik bydra tot die verspreiding van die nauplii wanneer hul uitbroei. Daar was geen beduidende voorkeur tussen die dorsale, median en ventrale vashegtings areas nie (p-waarde = 0.000542). Beduidende voorkeur tussen die distale, sentrale en proksimale streke (p-waarde = 1.19) was egter waargeneem. Fryer (1965) het waargeneem dat die patologie wat deur verteenwoordigers van die genus Ergasilus veroorsaak word afhang van die vashegtingposisie op die gasheer. Parasiete verskil ten opsigte van die morfologie van hul tweede antennas. Sommige het hakies en ander is langer wat hul instaat stel om, om die kieufilamente te vou. Die studie wys hoe Ergasilus sarsi (met geen hakies op die tweede antenna) om die kieufilament vou en sodoende aansienlike skade veroorsaak. Die hele kieufilament struktuur word verander as gevolg van lamellêre samesmelting en proliferasie van mukus-en epiteelselle. Vergelyking van 'n besmette kieu met ‘n gesonde kieu vertoon groot verskille. Die kompressie wat veroorsaak word deur die tweede antennas veroorsaak dat sommige bloedvate bars wat lei tot bloeding. Swempote van die parasiet het ook aansienlike skade veroorsaak deur die kieuweefsel van die gasheer af te skraap en dan voorentoe te druk na die mond gedeeltes van die parasiet. Slymselle, kieu-epiteel en bloedselle is waargeneem in die omgewing van v die parasiet se mond sowel as in die intestinum van die parasiet. ‘n Toename in die aantal Rodletselle en mastselle is waargeneem op die kieue in die omgewing van die parasiet. ‘n Toename in dié selle dui op ‘n inflamatoriese reaksie van die gasheer. Dit is die eerste rekord van Ergasilus sarsi op Lamprichtys tanganicanus, in Tanganjika- meer. Hierdie studie verskaf ook die eerste gedetallieerde beskrywing van die patologie wat veroorsaak word deur E. sarsi asook die besmettings statistiek van die parasiet. Tekortkominge van die studie sowel as moontlike toekomstige studies word in die laaste samevattende hoofstuk bespreek. vi TABLE OF CONTENTS ABSTRACT ..................................................................................................................................................III OPSOMMING ............................................................................................................................................... V LIST OF FIGURES ..................................................................................................................................... VII LIST OF TABLES........................................................................................................................................ IX 1 GENERAL INTRODUCTION ............................................................................................................... 2 1.1 MORPHOLOGY AND ECOLOGY ....................................................................................................................... 3 1.1.1 Background on Taxonomy ....................................................................................................... 3 1.1.2 Background on Ergasilus .......................................................................................................... 6 1.1.3 Background on the species found in Lake Tanganyika ..................................................... 27 1.2 OBJECTIVES OF THIS STUDY ......................................................................................................................... 28 1.2.1 Outline of the dissertation ....................................................................................................... 29 1.2.2 Oral presentations ................................................................................................................... 30 1.2.3 Special awards received during this study ........................................................................... 31 2 PATHOLOGY AND INFECTION STATISTICS ................................................................................ 33 2.1 INTRODUCTION ........................................................................................................................................ 33 2.2 MATERIALS AND METHODS: ....................................................................................................................... 34 2.3 RESULTS ................................................................................................................................................