Terrapins are one of the most endangered vertebrate groups, with almost half of the more than 300 extant species threatened with extinction. This study was conducted to investigate parasite host-switching from the invasive American Red-eared slider, Trachemys scripta elegans, to the native Mediterranean pond terrapin, Mauremys leprosa in natural environments in southern France and Spain. The study also included a risk assessment approach that was developed to assess the viability of the native M. leprosa terrapins in a small river of southern France. The diversity of haemogregarine parasites within South African terrapins was also explored. The thesis is structured as follows: CHAPTER 1 gives a broad introduction to reptiles and chelonians as well as the importance of chelonians in ecosystems with emphasis to the threats that are driving terrapins to decline. The various terrapin species examined during this study as well as the parasite groups of interest (Monogenea and Apicomplexa) are also discussed in detail. CHAPTER 2 documents the extent of platyhelminth invasions from T. s. elegans to natural M. leprosa populations in northern Spain and southern France. From DNA barcoding analysis based on the sequencing of the Cytochrome c Oxidase I gene, the inferred Minimum Evolution tree and p-distance comparisons of closely related haplotypes revealed a greater polystome richness within M. leprosa than expected, suggesting that host switching may take place in natural environments. T. s. elegans would serve as a carrier for a variety of polystomes that usually infest American turtles in their home range. These are transmitted to M. leprosa throughout the south of France, also suggesting that turtle polystomes are not strictly host-specific. CHAPTER 3 investigates polystome egg production under changing environmental conditions. The experimental procedure that was conducted on M. leprosa showed that environmental temperature has an effect on the egg laying rhythm of its parasite, i.e., Neopolystoma sp., with a two day lag of egg production in response to environmental temperature change. Results suggest the adaptability of the parasite to the physiology of their chelonian hosts which are ecthothermic animals. They also show that eggs production may be attributable to the release of host factors like hormones that once secreted may act and stimulate parasite reproduction. CHAPTER 4 relates risk assessment for the viability of the native Mediterranean pond terrapin (M. leprosa) in a natural environment by using the Relative Risk Model (RRM) method, taking into consideration various threats and environmental conditions that may impact this species. CHAPTER 5 examines the diversity of South African terrapin haemogregarines (Protozoa: Apicomplexa: Haemogregarinidae) as well as their phylogenetic placement among haemogregarines based on molecular and morphological evidences. CHAPTER 6 summarizes all findings of the study and explores new ways of Research. / PhD (Zoology), North-West University, Potchefstroom Campus, 2014

Monogeneans are mainly ectoparasitic on fish, but the family Polystomatidae radiated onto tetrapods and can be found on the skin and gills of the Australian lungfish, in the urinary bladder of frogs, gills and skin of salamanders, cloaca and phalodeum of caecileans, on the eye, nostrils, mouth, cloaca or urinary bladder of freshwater turtles, and on the eye of the hippopotamus. These host organisms are ecologically related through their association with freshwater habitats that favour parasite transmission. Firm attachment is critical to maintain a close relationship with their hosts. Attachment organs usually comprise of several units that are semi related to each other due to the need to form a functional unit. Interactions between subunits are expected to be under stabilising selection, and therefore hinder evolutionary change. Monogeneans are renowned for their effective posterior attachment structures in the form of hooks or hamuli and suckers that secure them, permanently or semi-permanently, to their hosts. The aim of this study was to investigate the morphology and functioning of attachment organs of selected polystomes representing different genera. A number of genera were selected in the study of attachment structures, genera included: Protopolystoma, Polystoma, Eupolystoma, Neopolystoma, Polystomoides and Oculotrema. Light microscopy and scanning electron microscopy was used to study the external morphology. Histology followed by light microscopy, confocal microscopy and enzyme digestion techniques followed by scanning electron microscopy was used to study the internal morphology. It was found that variation in haptoral components do exist, even among congeners, living for example in the bladder and oral cavity of the same host. Environmental factors relating to host ecology need to be taken into account when studying the morphology of monogenean haptors. Such factors play an important role in the adaptation of monogeneans and have possibly led to the change in microhabitats, which in turn explain the variation of haptoral components between parasites. Not all haptoral structures necessarily function in attachment throughout the entire life of the parasite and different haptoral structures are important for attachment to the host at different developmental stages of the parasite. / PhD, North-West University, Potchefstroom Campus, 2015

Terrapins are one of the most endangered vertebrate groups, with almost half of the more than 300 extant species threatened with extinction. This study was conducted to investigate parasite host-switching from the invasive American Red-eared slider, Trachemys scripta elegans, to the native Mediterranean pond terrapin, Mauremys leprosa in natural environments in southern France and Spain. The study also included a risk assessment approach that was developed to assess the viability of the native M. leprosa terrapins in a small river of southern France. The diversity of haemogregarine parasites within South African terrapins was also explored. The thesis is structured as follows: CHAPTER 1 gives a broad introduction to reptiles and chelonians as well as the importance of chelonians in ecosystems with emphasis to the threats that are driving terrapins to decline. The various terrapin species examined during this study as well as the parasite groups of interest (Monogenea and Apicomplexa) are also discussed in detail. CHAPTER 2 documents the extent of platyhelminth invasions from T. s. elegans to natural M. leprosa populations in northern Spain and southern France. From DNA barcoding analysis based on the sequencing of the Cytochrome c Oxidase I gene, the inferred Minimum Evolution tree and p-distance comparisons of closely related haplotypes revealed a greater polystome richness within M. leprosa than expected, suggesting that host switching may take place in natural environments. T. s. elegans would serve as a carrier for a variety of polystomes that usually infest American turtles in their home range. These are transmitted to M. leprosa throughout the south of France, also suggesting that turtle polystomes are not strictly host-specific. CHAPTER 3 investigates polystome egg production under changing environmental conditions. The experimental procedure that was conducted on M. leprosa showed that environmental temperature has an effect on the egg laying rhythm of its parasite, i.e., Neopolystoma sp., with a two day lag of egg production in response to environmental temperature change. Results suggest the adaptability of the parasite to the physiology of their chelonian hosts which are ecthothermic animals. They also show that eggs production may be attributable to the release of host factors like hormones that once secreted may act and stimulate parasite reproduction. CHAPTER 4 relates risk assessment for the viability of the native Mediterranean pond terrapin (M. leprosa) in a natural environment by using the Relative Risk Model (RRM) method, taking into consideration various threats and environmental conditions that may impact this species. CHAPTER 5 examines the diversity of South African terrapin haemogregarines (Protozoa: Apicomplexa: Haemogregarinidae) as well as their phylogenetic placement among haemogregarines based on molecular and morphological evidences. CHAPTER 6 summarizes all findings of the study and explores new ways of Research. / PhD (Zoology), North-West University, Potchefstroom Campus, 2014

Monogeneans are mainly ectoparasitic on fish, but the family Polystomatidae radiated onto tetrapods and can be found on the skin and gills of the Australian lungfish, in the urinary bladder of frogs, gills and skin of salamanders, cloaca and phalodeum of caecileans, on the eye, nostrils, mouth, cloaca or urinary bladder of freshwater turtles, and on the eye of the hippopotamus. These host organisms are ecologically related through their association with freshwater habitats that favour parasite transmission. Firm attachment is critical to maintain a close relationship with their hosts. Attachment organs usually comprise of several units that are semi related to each other due to the need to form a functional unit. Interactions between subunits are expected to be under stabilising selection, and therefore hinder evolutionary change. Monogeneans are renowned for their effective posterior attachment structures in the form of hooks or hamuli and suckers that secure them, permanently or semi-permanently, to their hosts. The aim of this study was to investigate the morphology and functioning of attachment organs of selected polystomes representing different genera. A number of genera were selected in the study of attachment structures, genera included: Protopolystoma, Polystoma, Eupolystoma, Neopolystoma, Polystomoides and Oculotrema. Light microscopy and scanning electron microscopy was used to study the external morphology. Histology followed by light microscopy, confocal microscopy and enzyme digestion techniques followed by scanning electron microscopy was used to study the internal morphology. It was found that variation in haptoral components do exist, even among congeners, living for example in the bladder and oral cavity of the same host. Environmental factors relating to host ecology need to be taken into account when studying the morphology of monogenean haptors. Such factors play an important role in the adaptation of monogeneans and have possibly led to the change in microhabitats, which in turn explain the variation of haptoral components between parasites. Not all haptoral structures necessarily function in attachment throughout the entire life of the parasite and different haptoral structures are important for attachment to the host at different developmental stages of the parasite. / PhD, North-West University, Potchefstroom Campus, 2015

The ectoparasitic monogenean fluke, Gyrodactylus salaris, is a parasite known to be highly pathogenic to Atlantic salmon (Salmo salar). Although present in the environment of several neighbouring European countries, the UK is thought to be G. salaris-free, but, if national contingency plans to control this parasite are to be effective, it is vital that we understand the factors underlying its transmission from host to host. This study demonstrates that the majority of parasites transferring to new hosts are mature parasites that have reproduced at least once. Since, exploration and host transfer strategies pose a risk to survival; the parasite will endeavour to pass on its genes before attempting to transfer from one host to another. This study has also shown that when pregnant parasites are forced to leave their hosts, their offspring are aborted prematurely to ensure the survival of the mature parasite. Gyrodactylids do not possess a free-swimming stage in their life cycle, which allows for their migration between hosts. In spite of this, they are able to rapidly colonise naïve hosts, even in non-shoaling populations of fish. This study investigates the transmission strategies employed by detached parasites in the colonisation of new hosts. Observations of gyrodactylids collected from 3-spine sticklebacks, Gasterosteus acuelatus, suggest that their activity increases as a stickleback approaches, alerting the host to its presence. The parasite is then ingested directly by the prospective host. A time series of experimental exposures and specimens prepared for Scanning Electron Microscopy (SEM) suggest that once ingested, the parasites attach to the lining of the buccal cavity and then migrate out to their preferred colonisation site on the outer surface of the fish. It is proposed that this may be an alternative route for host infection. Similarly, direct ingestion by the scavenging on infected hosts by 3-spine sticklebacks suggests another route of infection of new hosts. Although these routes of transmission may be of lesser significance, infections in the buccal cavity may be an important indicator for detection of infection and those personnel involved in screening fish for gyrodactylids should be aware that this is an area in which infections can occur. This study also demonstrated that the use of the anaesthetic 2-phenoxyethanol does not affect the number of gyrodactylids which leave the host to colonise a new host. Additionally, observations of the transmission process suggest that turbulence produced by the movement of the fish’s fins may facilitate the transfer of detached parasites from the substrate. While this hypothesis appears to be supported by video evidence and photographic stills gathered throughout the duration of this study, further work should be conducted using particle tracking techniques to determine the efficacy of using a vortex effect as a means of colonising new hosts. Field sampling processes may have an effect on this type of research, giving rise to problems with the accurate diagnosis, management and control of gyrodactylids in a variety of fish. Gyrodactylus infected specimens of 3-spine stickleback (Gasterosteus aculeatus L.), minnows (Phoxinus phoxinus L.) and stone loach (Barbatula barbatula L.) from one Scottish river were cohabited. The study found that small numbers of Gyrodactylus do transfer to atypical hosts. This study highlights that personnel involved in fish disease surveillance programmes should be aware of the consequences of transporting multiple species in the same transport vessel as gyrodactylids may infect species previously thought to be resistant. Equally, diagnosticians should be aware of the fact that atypical species may act as temporary hosts and that their gyrodactylid fauna should not be assumed. Non-feeding life-cycle stages, such as the dispersal stages of parasites, are dependant for survival upon finite energy reserves gathered during feeding phases. Thus, those individuals with more limited reserves will die sooner and consequently have less time available to find a new host once detached. At this stage, the principal energy reserves in gyrodactylids are stored as large lipids droplets. Confocal laser scanning microscopy (CLSM) has been used to investigate the distribution of lipid droplets in Gyrodactylus, which have migrated off their fish host, testing the hypothesis that these droplets function as a proxy for the nutritional state. This study, demonstrated that the lipid droplets were particularly associated with the gut and that there is a significant variability in the volume of stored lipid carried out by each individual. Transmission Electron Microscopy (TEM) showed that gyrodactylids carry lipid droplets at all stages of their life cycle, including at release from the birth pore. It is likely that transferring worms require stored energy reserves to survive in the event of failure to establish contact with a new host. These reserves could allow the parasite to survive without a host for several days. As gyrodactylids appear to respond to a range of stimuli including vibration and chemicals released from the host, the presence or absence of such cues may have consequences on the rates of Gyrodactylus transmission. If these chemical stimuli can be identified and then mimicked or blocked, then this may offer potential opportunities for the control of gyrodactylid behaviour and for disrupting their transmission to new hosts. Baseline gyrodactylid behaviour, in the absence of a host, was determined under white light and infrared. This was achieved using a specially constructed arena and purpose written image analysis software to analyse parasite movement under different lighting conditions. The study found that gyrodactylids were more active in the dark than in light conditions, typically displaying longer, more sinuous tracks under red light than under white light. To begin investigating the effect of chemical presence on gyrodactylid behaviour, the activity of octopaminergic agonists and antagonist which bind to muscle receptors and alter muscle activity, were assessed. The impact of octopamine hydrochloride, clonidine hydrochloride, amitraz and, a toxic reference, chlordimeform, over a range of concentrations (0.2 to 3.2µM/L) were assessed on gyrodactylid behaviour. All of the four chemicals affected Gyrodactylus and produced muscle tetanus, causing muscle spasms when extension was attempted. Prolonged exposure resulted in death. Only the highest concentration of chlordimeform, the toxic reference, affected 100% of Gyrodactylus after 24 hours. After 48 hours, all of the Gyrodactylus treated with chlordimeform were either affected, moribund or dead. Amitraz was more toxic than chlordimeform with 80% of Gyrodactylus being dead after 24 hours at the highest concentration. After 48 hours 100% of Gyrodactylus exposed to 3.2 µm/L amitraz were dead, and up to 80% were dead in those exposed to lower concentrations; with no parasites being left unaffected. Although these particular compounds are toxic to fish, the effect of these agonistic chemicals on Gyrodactylus behaviour and survival is interesting and suggests that a closely related compound that is safe for use against fish may offer a potential treatment for the control of G. salaris infections in rivers. An ultrastructure study was undertaken to contribute to the current understanding of gyrodactylid ultrastructure. The findings of this research require broad understanding of gyrodactylid behaviour for their interpretation. Photographic evidence was gathered using transmission and electron microscopy. From these results, it is clear that Gyrodactylus gasterostei on a three-spine stickleback host will respond to a range of stimuli (i.e. vibration or chemical cues released from the host) in their assessment of host suitability.

The blood processing mechanisms in monogeneans of the subclass Polyopisthocotylea are known from ultrastructural and histochemical analyses only. In contrast to other blood- feeding parasites, just few biochemical and molecular analyses have been done on digestive enzymes in monogeneans. Therefore, we focused on the biochemical and molecular characterization of hydrolytic enzymes (peptidases) in the hematophagous species Paradiplozoon bliccae and Eudiplozoon nipponicum. The presence of the cysteine class peptidases, mainly cathepsin L, in excretory- secretory products and soluble protein extracts of P. bliccae and E. nipponicum we found. Detection was carried out using fluorogenic substrates, specific inhibitors and the labelled probe DCG-04. On the gels / membranes after electrophoresis / blotting we detected bands of approximately size of 35 kDa in the case of both species and 24 kDa for E. nipponicum. Soluble protein extracts of worms were separated by 2D gel electrophoresis and relevant spots around 35 kDa (P. bliccae) and around 25 ˗ 35 kDa (E. nipponicum) were confirmed by mass spectrometry as cathepsins L. Using degenerate primers based on the conserved motifs of cysteine class peptidases, a partial sequence of cathepsin L gene from E. nipponicum was obtained. Furthermore, 3'RACE PCR method...

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-02-27T18:03:38Z No. of bitstreams: 1 2017 - Fabiano Paschoal de Oliveira.pdf: 3969824 bytes, checksum: 01879ccf451104bee02c819243b351cc (MD5) / Made available in DSpace on 2018-02-27T18:03:38Z (GMT). No. of bitstreams: 1 2017 - Fabiano Paschoal de Oliveira.pdf: 3969824 bytes, checksum: 01879ccf451104bee02c819243b351cc (MD5) Previous issue date: 2017-04-06 / CAPES / Between the period from march 2013 to november 2016 were collected and analyzed 195 specimens of hosts belonging to 25 species of actinopterygian fishes in Brazil, with the objective of perform a taxonomic study of your parasitic monogeneans and copepods. Two species of monogeneans, Sciadiclethrum araguariensis Paschoal, Scholz, Tavares-Dias & Luque, 2016 and S. edgari Paschoal, Scholz, Tavares-Dias & Luque, 2016 were described from two cichlids from the Araguar? River, State of Amap?, northern Brazil; in addition to the new species, new host and geographical records of six dactylogyrid monogeneans from cichlid fishes are presented from the Araguar? River and the Xing? River, State of Par?, Brazil. Two copepods of the family Philichthyidae Vogt, 1877, Colobomatus kimi Paschoal, Pereira & Luque 2016 and Leposphilus vogti Paschoal, Nagasawa & Luque 2016 parasites in the Upeneus parvus (Poey) and Micropogonias furnieri (Desmarest), respectively, in the litoral of the state of Rio de Janeiro, Brazil, are described and illustrated; In addition, an amendment diagnosis of the genus Leposphilus is provided based on the characters found in the present work. The copepod Hatschekia sp. n. is described based specimens collected on the haemulid fishes Anisotremus virginicus (Linnaeus) and A. surinamensis (Bloch) in the Bay of Angra dos Reis, State of Rio de Janeiro, Brazil, being this the first species of the family Hatschekiidae Kabata, 1979 described from the coast of Brazil. Beyond the descriptions s?o fornecidas novas informa??es sobre 15 esp?cies de cop?podes parasitas de 12 esp?cies de peixes marinhos de diferentes localidades litor?neas no Brasil; Are provided new information about 15 species of parasitic copepods found on 12 marine species of fishes in Brazil; these data including 12 new host records, eight new geographical records (locality) and first record of the genera Cresseyus and Pseudochondracanthus in the western South Atlantic. / Entre o per?odo de mar?o de 2013 a novembro de 2016 foram coletados e analisados 195 esp?cimes de hospedeiros pertencentes a 25 esp?cies de peixes actinopter?geos no Brasil, com objetivo de realizar um estudo taxonomico de seus monogen?ticos e cop?podes parasitas. Duas esp?cies de monogen?ticos, Sciadiclethrum araguariensis Paschoal, Scholz, Tavares-Dias & Luque, 2016 e S. edgari Paschoal, Scholz, Tavares-Dias & Luque, 2016 foram descritas a partir de dois ciclideos do rio Araguar?, Estado do Amap?, norte do Brasil; al?m das duas esp?cies, foram apresentados novos registros de hospedeiros e geogr?ficos de seis monogen?ticos dactilogir?deos a partir de peixes ciclideos do rio Araquari e do rio Xing?, Estado do Par?, Brasil. Dois cop?podes da fam?lia Philichthyidae Vogt, 1877, Colobomatus kimi Paschoal, Pereira & Luque 2016 e Leposphilus vogti Paschoal, Nagasawa & Luque 2016 parasitas de Upeneus parvus (Poey) e Micropogonias furnieri (Desmarest), respectivamente, do litoral do estado do Rio de Janeiro, Brasil, foram descritas e ilustradas; ademais uma altera??o do diagn?stico gen?rico de Leposphilus ? fornecido com base nos caracteres encontrados no presente trabalho. O cop?pode Hatschekia sp. n. ? descrita e ilustrada a partir de esp?cimes coletados dos peixes haemulideos Anisotremus virginicus (Linnaeus) e A. surinamensis (Bloch) provenientes da Ba?a de Angra dos Reis, Estado do Rio de Janeiro, Brasil, sendo esta a primeira esp?cie da fam?lia Hatschekiidae Kabata, 1979 descrita a partir do litoral do Brasil. Al?m das descri??es s?o fornecidas novas informa??es sobre 15 esp?cies de cop?podes parasitas de 12 esp?cies de peixes marinhos de diferentes localidades litor?neas no Brasil; estes dados incluem 12 novos registros de hospedeiros, 08 novos geogr?ficos (de localidade) e primeiros registros dos g?neros Cresseyus e Pseudochondracanthus no oeste do Atl?ntico Sul.

Of the 430+ extant species of Gyrodactylus, ectoparasitic monogenetic flukes of aquatic vertebrates, Gyrodactylus salaris Malmberg, 1957 is arguably the most well-known. Following the introduction of this species into Norway in the 1970s with consignments of infected Atlantic salmon smolts, Salmo salar L., this species has had a devastating impact on the Norwegian Atlantic salmon population, decimating wild stocks in over 40 rivers. Gyrodactylus salaris is the only OIE (Office International des Epizooties) listed parasitic pathogen of fish and has been reported from 19 countries across Europe, though many of these records require confirmation. The UK, Ireland and some selected watersheds in Finland are currently recognised as G. salaris-free states; however, the threat that this notifiable parasite poses to the salmon industry in the UK and Ireland is of national concern. Current British contingency plans are based on the assumption that if G. salaris were to be introduced, the parasite would follow similar dynamics to those on salmonid stocks from across Scandinavia, i.e. that Atlantic strains of Atlantic salmon would be highly susceptible to infection, with mortalities resulting; that brown trout, Salmo trutta fario L., would be resistant and would lose their infection in a relatively short period of time; and that grayling, Thymallus thymallus (L.), would also be resistant to infection, but would carry parasites, at a low level, for up to 143 days. Two of the objectives of this study were to confirm the current distribution of G. salaris across Europe, and then, to investigate the relative susceptibility of British salmonids to G. salaris, to determine whether they would follow a similar pattern of infection to their Scandinavian counterparts or whether, given their isolation since the last glaciation and potential genetic differences, they would exhibit different responses. It has been almost six years since the distribution of G. salaris across Europe was last evaluated. Some of the European states identified as being G. salaris-positive, however, are ascribed this status based on misidentifications, on partial data resulting from either morphological or molecular tests, or according to records that have not been revisited. Additional Gyrodactylus material from selected salmonids was obtained from several countries to contribute to current understanding regarding the distribution of G. salaris across Europe. From the work conducted in the study, G. salaris is reported from Italy for the first time, alongside three other species, and appears to occur extensively throughout the central region without causing significant mortalities to their rainbow trout, Oncorhynchus mykiss (Walbaum), hosts. The analysis of archive material from G. salaris-positive farms would suggest that G. salaris has been in the country for at least 12 years. Material obtained from rainbow trout from Finland and Germany was confirmed as G. salaris supporting existing data for these countries. No specimens of G. salaris, however, were found in the additional Gyrodactylus material obtained from Portuguese and Spanish rainbow trout, only Gyrodactylus teuchis Lautraite, Blanc, Thiery, Daniel et Vigneulle, 1999, a morphologically similar species was found. Gyrodactylus salaris is now reported from 23 out of ~50 recognised states throughout Europe, only 17 of these however, have been confirmed by either morphology or by an appropriate molecular test, and only ten of these records have been confirmed by a combination of both methods. To assess the susceptibility of English and Welsh salmonids to G. salaris, a number of salmonid stocks of wild origin, were flown to the Norwegian Veterinary Institute (NVI) in Oslo, where they were experimentally challenged with G. salaris. Atlantic salmon from the Welsh River Dee, S. trutta fario from the English River Tyne and T. thymallus from the English River Nidd, raised from wild stock in government hatcheries, were flown out and subsequently challenged with G. salaris haplotype A. After acclimation, each fish was infected with ~50–70 G. salaris and marked, so that parasite numbers on individual fish could be followed. The dynamics on individual fish were followed against a control (Lierelva Atlantic salmon). The experiment found that the number of G. salaris on S. salar from the River Dee continued to rise exponentially to a mean intensity (m.i.) of ~3851 G. salaris fish-1 (day 40 post-infection). These salmon were highly susceptible, more so than the Norwegian salmon control (m.i. ~1989 G. salaris fish-1 d40 post-infection) and were unable to regulate parasite numbers. The S. trutta fario and T. thymallus populations, although initially susceptible, were able to control and reduce parasite burdens after 12 (m.i. ~146 G. salaris fish-1) and 19 (m.i. ~253 G. salaris fish-1) days, respectively when peak infections were seen. Although the latter two hosts were able to limit their G. salaris numbers, both hosts carried infections for up to 110 days (i.e. when the experiment was terminated). The ability of S. trutta fario and T. thymallus to carry an infection for long periods increases the window of exposure and the potential transfer of G. salaris to other susceptible hosts. The potential role that brown trout may play in the transmission and spread of G. salaris in the event of an outbreak, needs to be considered carefully, as well as the interpretation of the term “resistant” which is commonly used when referring to brown trout’s susceptibility to G. salaris. The current British surveillance programmes for G. salaris are focused on the screening of Atlantic salmon and on the monitoring of the rainbow trout movements. The findings from this study demonstrate that G. salaris can persist on brown trout for long periods, and suggest that brown trout sites which overlap with Atlantic salmon or rainbow trout sites are also included within surveillance programmes and that the role that brown trout could play in disseminating infections needs to be factored into contingency/management plans. Throughout the course of the study, a number of parasite samples were sent to the Aquatic Parasitology Laboratory at Stirling for evaluation. Some of these samples represented Gyrodactylus material that were associated with fish mortalities, but the species of Gyrodactylus responsible appeared to be new to science. A further aspect of this study was, therefore, to investigate these Gyrodactylus related mortalities in aquaculture stock and to describe the species found in each case, which may represent emerging pathogens. The two new species, Gyrodactylus orecchiae Paladini, Cable, Fioravanti, Faria, Di Cave et Shinn, 2009 and Gyrodactylus longipes Paladini, Hansen, Fioravanti et Shinn, 2011 on farmed gilthead seabream, Sparus aurata L., were collected from several Mediterranean farms. The finding of G. orecchiae in Albania and Croatia was associated with 2–10% mortality of juvenile stock and represents the first species of Gyrodactylus to be formally described from S. aurata. Subsequently, G. longipes was found in Bosnia-Herzegovina and Italy, and at the Italian farm site, it occurred as a mixed infection with G. orecchiae, but these infections did not appear to result in any loss of stock. Unconfirmed farm reports from this latter site, however, suggest that a 5–10% mortality of juvenile S. aurata was also caused by an infection of Gyrodactylus, which is suspected to be G. longipes. Additional samples of Gyrodactylus from a gilthead seabream farm located in the north of France have been morphologically identified as G. longipes, extending the geographical distribution of this potentially pathogenic species to three countries and three different coasts. In addition to these samples, some specimens of Gyrodactylus from a Mexican population of rainbow trout were sent for evaluation.

Ph.D. / Members of Cichlidogyrus are monogenean ectoparasites occurring on the gill filaments of mainly cichlid fishes. An overview of the taxonomic background of the genus and motivation for the study is provided. In this study, existing information on their distribution is organised in a comprehensive table which includes 85 species, their taxonomic authors, hosts and localities from which they have been recorded. Representatives of this genus occur mainly in Africa, but have been found on cichlids as far as Mexico. Host specificity of members of the group is discussed. During the present investigation specimens of the genus Cichlidogyrus were found parasitising Pseudocrenilabrus philander philander, in the Padda Dam in Johannesburg, Gauteng, South Africa. Specimens were examined and identified as Cichlidogyrus philander, previously described from the same host, from Lake Kariba, in Zimbabwe. The morphology was studied utilizing light – and scanning electron microscopy. Specimens were stained with Horen‟s trichrome and photographed. Furthermore 100 whole mounted specimens, which were fixed and mounted in glycerine-ammonium-picrate, were measured. Larval specimens, and mature individuals with eggs in situ, were examined. The investigation of the ecology entailed monthly surveys during which a total of 245 fish specimens were collected with the aid of hand nets, over a period of 14 months (from March 2006 to June 2007). The fish were transported to the laboratory and killed by severing the spinal cord. Gills of specimens of P. p. philander (111), Gambusia affinis (105), Tilapia sparmanii (28) and one (1) 2 specimen of Cyprinus carpio were inspected, for the presence of monogeneans, with the aid of a dissection microscope. Only members of P. p. philander were parasitised by C. philander, indicating strict host specificity. The number of specimens varied from 0 to 184 per fish. The highest mean intensity of 91.6 occurred in the winter month of June 2007, although no significant correlation between season and the occurrence of this parasite was recorded. The prevalence was 100 % for ten of the fifteen surveys and no preference for host sex was recorded. The intensity of the infection correlates positively to the total length of the host, i.e. larger hosts harbour more worms. A positive correlation between condition factor and the total number of worms was found, indicating that more parasites are found on fish with a normal condition factor. No significant difference occurred between the numbers of parasites collected from gill arches on the left or right sides of fish. Statistical analysis of data showed that parasites disperse across the four gill arches with a higher proportion of parasites on the third and second gill arch. The highest proportion of the collected parasites occurred on the dorsal regions and on the distal ends of the gill filaments. Water quality variables do not significantly correlate to the prevalence, abundance or mean intensity of this parasite. This is the first ecological study conducted on specimens of C. philander, worldwide.

>Magister Scientiae - MSc / Aquaculture is a vast industry all over the world and has increased significantly during the past 30 years. In South Africa, finfish aquaculture farms stretch from Gansbaai to as far as Richards bay with the potential of extending into Mozambique. The future success of this fast growing industry in South Africa strongly relies on the development of the supporting sector such as government legislation, sponsorship, participation of the pharmaceutical industry and research and development in aquatic organism health management. Diplectanum oliveri Williams, 1989, a monogenean gill parasite of both Argyrosomus japonicus (Temminck & Schlegel, 1843) (dusky kob) and A. inodorus Griffiths & Heemstra, 1995 (silver kob) is currently regarded in South Africa as the most persistent ectoparasite associated with the culture of both fish species, causing pathological tissue changes in the areas associated with attachment and feeding which can result in stock losses. The egg production of D. oliveri was used to evaluate and develop a method to quantify monogenean infections on fish, by counting the eggs produced by infra-populations of these parasites over a 24-hour period and to determine the reliability of this method as a non-invasive/non-destructive method to quantify the intensity of an individual infra-population of parasites on a single host. Currently, Diplectanum spp. on dusky kob are being controlled in local mariculture facilities using methods and drugs that are traditionally used for monogeneans (flukes) and are regarded as effective. Most of these drugs are, however, no longer approved for use in food fish and none of them has proven to be very effective in controlling D. oliveri in culture facilities, which can result in subsequent re-infections of epidemic proportion. Currently, there are no anthelmintics registered for aquaculture in South Africa. An registered anthelmintic used in terrestrial animals (sheep, goats, cattle and ostriches) containing praziquantel was tested at various concentrations and exposures against D. oliveri on A. japonicus to determine the efficacy of two different formulations and the potential for "off label" use. The 20 ppm (high) praziquantel concentration treatments eliminated all adult parasites, but caused significant measureable stress and affected the central nervous system of the fish, which resulted in death of all fish in the solution group after 18 hours. The 2 ppm (low) concentrations failed to remove all adult parasites. Although both the 2 hour (short) exposure/high concentration and 24 hour (long) exposure/low concentration of the suspension formulation were effective, but only the short exposure/high concentration eliminated all adult parasites with little change in behaviour by the treated fish.