Ph.D. / Within the order Isopoda, only a few families are known to be parasitic. Representatives from the family, Cymothoidae, are obligate parasites of both marine and freshwater fishes. In South Africa, information regarding these isopods is scanty and the little that is known is mostly outdated and inaccurate. Currently only 12 species of cymothoid isopods are known from this region and thus it was hypothesised that with proper sampling and identification, this number would increase and that the known number is not a true reflection of the actual number of cymothoid isopods present. A complete revision of the southern African Cymothoidae is required and thus this project focussed on three of the least studied genera, Ceratothoa Dana, 1852, Cinusa Schioedte & Meinert, 1884, and Cymothoa Fabricius, 1787. The cymothoid isopods studied in this project were obtained from fresh collections along the southern African coast as well as from museum collections. The fresh material was obtained from various sampling trips along the east and south coasts of South Africa as well as from Zanzibar, Tanzania. The museum collections were loaned from a number of national and international museums, and preserved isopods were also collected from fish specimens housed in the South African Institute for Aquatic Biodiversity (SAIAB) museum. Isopods were dissected (if possible), drawn and described. Species descriptions were prepared in DELTA (Descriptive Language for Taxonomy) using a specifically constructed Cymothoidae data set. All valid members of the buccal inhabiting genera Ceratothoa, Cinusa and Cymothoa, were completely reviewed including a full account of the species synonymy, distribution, and known hosts as well as a few additional notes. Where applicable, a redescription of the type specimen was also provided and problematic combinations or issues in the species were discussed. Each species was then defined as valid, invalid or of questionable status and a complete reviewed species list for the genus was provided. According to the World Marine, Freshwater and Terrestrial Isopod Crustaceans database, there are 31 accepted Ceratothoa species names. After completion of the Ceratothoa review, eight species were considered questionable and another three were synonymised with other valid species. Thus, the species list was diminished to a total of 20 currently known and valid Ceratothoa species. In South Africa, another two new species were identified and described, which would increase the number of Ceratothoa species in this region to four, and will add another two species onto the world list once published.

Thesis (M.Sc. (Zoology)) -- University of Limpopo, 2020 / The present study was carried out in the Kwena Dam, with the aim of determining selected water quality parameters, parasite diversity and condition factor (K) of Clarias gariepinus (sharptooth catfish), Cyprinus carpio (common carp) and Oreochromis mossambicus (Mozambique tilapia). This study was conducted in autumn (April 2016), winter (July 2016), spring (October 2016) and summer (February 2017). The present study was the first to investigate the parasite composition of these three fish species in the Kwena Dam. A total number of 26 Clarias gariepinus, 21 Cyprinus carpio and 57 O. mossambicus specimens were collected using gill nets of different mesh sizes (30 mm – 120 mm). Each fish was weighed, measured and euthanised by severing the spinal cord. Mucus smears from the skin, fins and gills were examined for ectoparasites using a stereo-microscope. The fish were then dissected and all organs examined for endoparasites. All parasites were fixed and preserved according to standard methods for each parasite group. In situ water parameters were determined using a handheld multi-parameter instrument for each sampling season. In addition, water samples were collected seasonally and sent to an accredited laboratory where they were analysed for selected metals and nutrients. Water quality parameters and the presence of metals in water are of importance in determining the water quality of an aquatic environment. Most water quality parameters were within the Target Water Quality Range (TWQR) for aquatic ecosystems. Aluminium, selenium and zinc had concentrations above the TWQR for aquatic ecosystems. Nutrient concentrations were within the TQWR during all sampling seasons. The water quality did not differ significantly between seasons during the present study. Four parasite groups were reported infecting Cyprinus carpio and these included Monogenea (Dactylogyrus extensus and Dactylogyrus minutus), Digenea (Diplostomum sp.), Cestoda (Atractolytocestus huronensis), Branchiura (Argulus japonicus) and Copepoda (Neoergasilus japonicus). Parasites collected from Clarias gariepinus belonged to four groups, namely Protozoa (Trypanosoma sp.), Monogenea (Quadriacanthus sp. and Gyrodactylus sp.), Nematoda (Paracamallanus cyathopharynx and Contracaecum sp.) and Branchiura (Dolops ranarum). Parasites collected from O. mossambicus belonged to five groups, namely Monogenea (Cichlidogyrus halli, Cichlidogyrus sclerosus, Cichlidogyrus tilapiae and Enterogyrus conoratus), Nematoda (Contracaecum sp.), Cestoda (Neogryporhynchus sp.), Acanthocephala (Acanthogyrus tilapiae) and Branchiura (Dolops ranarum). iv The number of parasite species for the four seasons were as follows: summer (13) > autumn and winter (12) > spring (11). From the Shannon-Wiener index results, O. mossambicus had a higher parasite diversity than Clarias gariepinus and Cyprinus carpio. The Parasite Index (IP) and Inverted Parasite Index (IPI) of the three fish species indicated that the water from the dam is not polluted. The condition factor (K) for all fish species indicated that fish collected from the dam during all sampling seasons were in a good condition and parasite load had little effect on K for all fish species. The use of PI and IPI in conjunction with the fish K can be regarded as a useful tool in freshwater and fish health monitoring. The present results report new geographical records of the parasites of Clarias gariepinus, Cyprinus carpio and Oreochromis mossambicus. Since no parasitological research was done before the present study at the Kwena Dam, the results of the present study form baseline data for future parasitology studies and can consequently be useful in the management and conservation of the Kwena Dam. / DSI–NRF SARChI Chair (Ecosystem Health) of the University of Limpopo and the Limpopo Department of Economic Development and Tourism (LEDET)

A study has been carried out to investigate some aspects of the feeding and digestion of the parasitic copepod Lepeophtheirus salmonis (Kreyer, 1837), a serious pathogen of wild and farmed marine salmonids. The alimentary canal consists of a cuticularised foregut and hindgut and a midgut, the latter comprising most of the length of the alimentary canal. It consisted of an anterior diverticulum, and anterior midgut, mid midgut and posterior midgut. All the midgut is lined in the luminal side with a monolayer of digestive epithelium. The latter is supported by a porous basal membrane. Mesenteries suspend the gut in the haemocoel and attach to the basal membrane by means of extensions of their cytoplasm that interlock with the pores of the basal membrane and are intimately associated with the cellular basal membrane of the enterocytes. Four types of cells could be recognised ultrastructurally and were named according a widely accepted nomenclature for the types of digestive epithelial cells found in decapod crustaceans. R-cells were the most abundant type and were believed to be involved in the absorption of nutrients, storage of lipids and probably excretion of waste material. Once the R-cells have finished their useful life, it is proposed that they finally die after passing through a stage, called A-cell stage, comparable to apoptosis or programmed cell death, after which the A-cell is finally sloughed off the epithelium and discarded in the faeces. F-cells constituted the second cell type, in charge probably of the secretion of digestive enzymes. Once this stage is finished, F-cells are believed to transform into the third type of cells, the B-cells, which engage in intracellular digestion of nutrients. At the end of their useful life they are sloughed off the epithelium. The last cell type, the E-cells, are believed to be embryonic cells that differentiate either into R- or F-cells. A revised mode of feeding is proposed, in which the louse scoops up strips of host skin epithelium of relatively constant size and shape, by means of the structures associated with the mouth cone. Analysis of the gut contents and the faecal pellets revealed that the main food item was host skin epithelium. The feeding activity usually reaches the dermal layer, suggested by the common occurrence of host melanin in the gut and in the faecal pellets. Two types of faecal pellets were found. The first type was a cylindrical one which was made of the ingested host's epithelial cells with little signs of having being digested. Cylindrical pellets could be clear or dark depending on the amount of host melanin present in them. The second type of pellet was a tape- or ribbon-like gelatinous pellet produced mainly when the lice were not eating (as during starvation) or sometimes associated to the end of the cylindrical pellets. Pellets were always surrounded by a delicate peritrophic envelope composed of several peritrophic membranes. Blood was believed to be another important food item. Blood feeding was commonly associated with the production of lipids in the R-cells and it is proposed (but not confirmed) that this alternative food item could be associated with some physiological process that requires lipogenesis, like vitellogenesis. A method for manually feeding the lice was devised. Salmon blood and milk were fed in this way. No sign of digestion of these food items was observed suggesting that possibly an endogenous factor different from the presence of food in the gut is necessary to trigger the digestive process. An analysis of type of gut contents, peritrophic membranes and cell type occurrences during a digestive period was carried out. The results suggested that some digestive processes take place preferentially in one or another gut region. Mid and posterior midgut are probably associated with the production of faecal pellets, production of digestive enzymes, intracellular digestion and excretion of waste materials judging by the higher occurrence of peritrophic membranes, B- and A-cells in these regions. Absorption of nutrients probably takes place throughout the midgut. The morphological changes in the topography shown by the midgut epithelium suggest that it is a very active and plastic tissue. The results of this study were discussed and compared with similar studies of other crustaceans, including other parasitic and free living copepod species. Suggestions were made of the implications of the present findings in the search for a control method for this parasite.

The Rietvlei Dam near Pretoria, South Africa, provides drinking water for the city and for the wild life in the Rietvlei Nature Reserve, and is also used for recreational fishing. The dam is part of the Sesmyl Spruit system, which has a history of pollution, the major sources of which are industrial, agricultural and sewage from informal human settlements upstream of the reserve. With a large wetland separating the upstream Marais Dam and the Rietvlei Dam, the system has a high conservation priority status because of the high number of bird species that breed and roost in the various habitats. As part of a big aquatic health project in the Zoology Department, Rand Afrikaans University, aimed at finding suitable biomarkers for water quality monitoring in the system, this study was done to identify the major internal helminth parasites of the sharptooth catfish, Clarias gariepinus, that can be used in fish health assessment studies, and to determine their prevalence and intensity in the Rietvlei Dam. Fish were collected during one sampling survey and examined for endoparasites, also noting any ectoparasites that are recorded in routine fish health studies. Five species of helminths were identified: the adult cestodes, Polyonchobothrium clarias (intestine and stomach), Proteocephalus glanduliger (anterior intestine), the adult nematode Procamallanus laevionchus (stomach), larvae of the nematode Contracaecum sp. and many trematode metacercariae encysted in the muscles, of which only Ornithodiplostomum sp. was successfully excysted and identified. This trematode is recorded in South Africa for the first time, but could not be specifically identified because the reproductive system was still immature. Examination of piscivorous birds in the area or experimental infection of young birds are the only means by which the adult trematodes can be obtained. The adult cestodes and nematodes had specialised structures for attachment to the stomach and/or intestinal mucosa, adaptations associated with pathological effects in the host. Polyonchobothrium clarias had a crown of 26-30 hooks on its rostellum, and this number differs from those of specimens described from catfish in other African countries. Scanning electron microscopy showed that the rostellum of the P. clarias specimens from Rietvlei Dam was different from that of specimens from other localities in South Africa. Proteocephalus glanduliger in C. gariepinus from Rietvlei Dam differed in strobila size and size of glandular organ from specimens described by Janicki (Egypt) and Mashego (South Africa), the present specimens being much longer but with smaller glandular organs. Procamallanus laevionchus is a common parasite of catfish from many African countries, including South Africa, and scanning electron microscopy showed some form of transverse markings and presence of papillae-like structures at the posterior end of female specimens, an observation which was not described in previous studies. Larval Contracaecum are also common in C. gariepinus and other fish species, and adults have been identified in several species of fish-eating birds from South Africa. The sample size of fish collected in this survey was too low for a full health assessment index (HAI) study to be undertaken. Polyonchobothrium clarias and Contracaecum, however, were highly prevalent in the host species, and Contracaecum and Ornithodiplostomum occurred at high intensity (up to 44 and 140 respectively). Endoparasites of C. gariepinus can therefore be used in the fish HAI as a bioindicator of water quality. Only two ectoparasitic species were found on C. gariepinus: Argulus japonicus (skin and fins) and Lamproglena clariae (gills). Most water quality variables from the dam were within the target limits recommended by the Department of Water Affairs and Forestry, but the levels of inorganic nitrogen (nitrate and ammonia) and phosphorus (orthophosphate) exceeded the limit. If uncontrolled, these may lead to eutrophication of the dam. With the parasite species and diversity known, it is recommended that fish health assessments should be conducted along pollution gradients in the system to determine whether it can be incorporated into the suite of biomarkers for water quality monitoring of the Sesmyl Spruit system. / Prof. A. Avent-Oldewage

Thesis (M.SC. (Aquaculture)) --University of Limpopo, 2011 / The present MSc dissertation emanates from seasonal surveys conducted by the fish parasitological group of the Department of Biodiversity and Aquaculture Research Unit of the University of Limpopo, Turfloop Campus. The first part of the present study was aimed at investigating the metazoan parasites of three cyprinids occurring in the Nwanedi-Luphephe Dams. The main purpose of it was to determine temporal changes in the intensity of infestation in terms of prevalence, mean intensity and abundance of parasite species parasitizing the cyprinids studied over a two year period. Ecological parameters including species host-specificity, seasonality, and gender preference and host size versus species intensity are discussed for each parasite. Altogether 152 specimens were examined for parasites and a total of 2 432 metazoan parasites of ten species were recorded. At the sampling site, all three hosts co-occurred, however, a substantial proportion of Barbus radiatus was collected from the perennial stream feeding one of the twindams. Fish were sampled by means of gill nets and electrofishing or seine netting in accordance with the habitat conditions. Hosts were killed and organs investigated for metazoan parasites. After collection of parasites, standard methods for processing individual parasites were followed. The results obtained revealed the following groups of parasites; monogeneans (ectoparasites) included Dactylogyrus spinicirrus, D. afrolongicornis afrolongicornis, D. afrolongicornis alberti, Afrodiplozoon polycotyleus, Gyrodactylus sp., and Dogielius sp. (all recorded from the gills); Crustacea, Dolops ranarum was found from the mouth cavity, gills and skin of Labeobarbus marequensis. Of these, only two specialists, both monogeneans, were found on Barbus trimaculatus namely, D. afrolongicornis afrolongicornis and D. afrolongicornis alberti. Based on morphology of the haptoral hard parts, these two species were almost similar to each other than to D. spinicirrus. The appreciable difference between D. afrolongicornis afrolongicornis and D. afrolongicornis alberti was mainly in the shape of the marginal bar. Both D. spinicirrus and A. polycotyleus were widely distributed and recorded on the gills of all hosts during all seasons. Both species were recorded for the first time on B. radiatus. Also, D. spinicirrus was recorded for the first time on the gills of B. trimaculatus. Based on comparison with the original material, the species could be identified to species level. These analyses provided sufficient evidence for restoration of Afrodiplozoon polycotyleus as a valid taxon. The existence of two species, Gyrodactylus sp. and Dogielius sp. were recorded for the first time on B. radiatus in South Africa, and this possibly represents new species. The endoparasites included the following groups: digeneans- Diplostomulum metacercariae from the eyes of Lb. marequensis, Ornithodiplostomum sp. and black spot (grubs) were recorded from B. trimaculatus. The latter was also recorded in the muscle of B. radiatus. Unidentified digenean cysts were recovered from the gills and in the body cavity of both Lb. marequensis and B. trimaculatus; nematodes were represented by Contracaecum larvae in the body cavity of both Lb. marequensis and B. trimaculatus; cestodes were represented by gryporynchid larvae from the intestine of B. radiatus. The general high prevalence and intensities of ectoparasites recorded is an indication that the Nwanedi-Luphephe Dams has a biotic mechanism which might have enabled it to sustain the growth rate of ectoparasite intra-population. There was no correlation between either fish length or condition factor and the number of parasites. The study indicated that the abundance of monogeneans is partly influenced by season and that of endoparasites was principally governed by the presence of intermediate hosts and definitive hosts. The second part of this dissertation dealt with the health status of Lb. marequensis. Fish health was assessed using condition-related indices including condition factor and a modified Health Assessment Index (HAI) and the associated Parasite Index (PI). The HAI was performed to determine and examine any macroscopic abnormalities regarding external features and internal organs. The purpose of combining the two indices was to use the infestation of the metazoan parasites found on and/or in Lb. marequensis to determine whether or not the environment they live in was healthy. Both indices together with the condition factor provided relatively simple and rapid indications of how well fish were coping in their environment. The HAI score varied amongst the four sampling seasons. The highest individual mean value was 63 in winter, followed by a score of 50 in autumn, while the lowest were 42 and 33 in summer and spring respectively. To authenticate the HAI and PI data, certain water quality variables were measured and are discussed in detail in this dissertation. The Nwanedi-Luphephe Dams are generally believed to have good water quality. This was supported in this study; conditions assessed in fish using the aforementioned indices did not differ greatly between seasons, nor did the conditions deviate appreciably from normality. The HAI values were low overall which signifies a healthy fish profile for the system. The present investigation showed the existence of differences in the occurrence of individual parasite to be linked to water temperature changes. Thus, seasonal changes do influence parasite developmental stages to a certain degree. Tested heavy and trace metals were within the permissible limits as provided by the Department of Water Affairs and Tourism (DWAF, 1996).

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.

Collections of Saprolegniaceous fungi were made from diseased tropical fish. Nineteen strains, representing three fungal genera (<u>Saprolegnia</u>, <u>Achlya</u> and <u>Pythium</u>), were isolated from 11 fish species. Due to difficulty in inducing sexual fruiting, only two strains were identified to species; both of these being <u>A. americana</u>. Laboratory infection studies revealed the ability of strains of each different fungus to infect five selected tropical fish species. <u>Saprolegnia</u> sp. and <u>A. americana</u> proved to be more vigorous and lethal pathogens than <u>Pythium</u> sp. No indications of host specificity were evident. All chemicals tested (Table 4) showed definite fungicidal abilities. No effective fungicidal concentration of the chemicals tested would permit sustained fish culturing. Malachite green was the most effective fungicide tested, being functional in concentrations as low as 2 ppm. / Master of Science

Lernaeocera branchialis (Linnaeus, 1767) is a parasitic copepod possessing a complex dual-host lifecycle. The “definitive” gadoid hosts, including Gadus morhua (Atlantic cod), Melanogrammus aeglefinus (haddock) and Merlangius merlangus (whiting), are infected by the fertilised female, which penetrates the host’s ventral aorta or bulbus arteriosus whilst undertaking extensive metamorphosis and a haematophagous lifestyle. The pathogenic effects of this activity upon the host have been well documented and mortality may occur, especially when multiple parasites are present. These negative impacts on cod, particularly juveniles, by L. branchialis have the potential to adversely affect cod aquaculture in the future, and already vulnerable wild cod stocks. This PhD project therefore, investigated the immune response of wild haddock and cultured-cod post-infection by L. branchialis, and the possible mechanisms by which the parasite modulates/evades the host’s immune response. The systemic immune response of both wild haddock and cultured-cod post-infection by L. branchialis depended on the maturation stage of the parasite, and in the former host species, upon the infection intensity. Wild haddock harbouring fully metamorphosed females showed an increase in circulating thrombocytes and a decrease in serum protein levels however; if multiple mature L. branchialis were present the haddock possessed reduced circulating monocytes, and increased circulating thrombocytes and serum anti-trypsin activity. Infection by L. branchialis was also associated with a suppressive effect on haddock serum spontaneous haemolytic activity. These responses were thought to be due to the host trying to counteract the increased damage caused by the massive increase in size and the feeding of the mature parasite, which is more pronounced when multiple parasites are present, resulting in the increase in some parameters and the ‘consumption’ of others. However, the effect of parasite-derived secretions and other pathogens due to observations on wild fish could not be discounted. The laboratory-infection of cultured-cod from two different sources was also performed in order to study the immune response over time. The two groups of cod showed differences in their immune response to L. branchialis. The first group showed suppressed respiratory burst activity of phagocytes, as the parasite reached the early penella sub-stage, whilst no suppression in phagocyte respiratory burst activity was found in the second group. The parasite was found to migrate along the afferent branchial artery of the cod where a thrombus formed and was present throughout its migration into the ventral aorta. At 14 d post-infection, leukocytes expressing Interleukin 8 mRNA were observed within the free-flowing blood at the periphery of the organising thrombus within the lumen of the ventral aorta. This was speculated to aid the recruitment and activation of leukocytes to the site, and the maturation and neovascularisation of granulation tissue. The infection of the second group subsided with the death of the parasite, and none of the parasites metamorphosed past the early penella sub-stage. The live parasites infecting the first group of cod did not possess IgM or complement component C3 binding on their cuticle, however, both IgM and C3 binding occurred on the dead parasites in the second infection trial. This may highlight the importance of these opsonins and the cytotoxic effect of phagocytes in the elimination of L. branchialis by some cod. However, the first infection was terminated as the parasite reached the early penella sub-stage due to a loss of stock cod prior to the study, so the long-term success of the infection can not be concluded. Therefore, the immune response to infection needs to be determined over the entire metamorphosis of L. branchialis to determine whether the infection was successful or not, and preferably in populations with varying susceptibility to L. branchialis. This will not be possible without further studies into the resistance of different stocks of cultured-cod. Many arthropod parasites, such as ticks and salmon lice, have been previously documented to produce pharmacologically active secretions, aiding host invasion and parasite feeding, preventing the host immune response from working effectively against the parasite, all aimed at improving survival of the parasite. Therefore, the effects of the secretory/excretory products (SEPs) produced during the initial infective stage and by the mature, fully metamorphosed female on the immune response of cultured-cod in vitro, and the location of exocrine glands associated with the oral region of the parasite were investigated. The SEPs from the infective stage of the parasite were found not to affect the intracellular hydrogen peroxide (H2O2) production of phagocytes. The practical difficulties in collecting large quantities of the SEPs from the infective stage meant that their effects could not be tested on the other host immune parameters studied. The SEPs from fully metamorphosed female L. branchialis, however, had a number of suppressive effects on the host immune response in vitro including: 1) suppression of the intracellular production of cytotoxic H2O2 during the respiratory burst of phagocytic leukocytes post-PMA stimulation, 2) suppression of the production of macrophage activating factor by leukocytes with a priming effect on naïve phagocyte function, and 3) suppression of the chemo-attraction ‘power’ of zymosan activated cod serum, i.e. anaphylatoxin activity, on head kidney-derived leukocytes. These effects were dose-dependent, and highlight the capacity of L. branchialis to suppress its host’s innate immune response at the local feeding area. Further work is required to establish the mechanisms by which the parasite-derived SEPs suppress these host immune parameters, and to identify which molecules produced by the parasite are responsible. The correlation between these in vitro results, and systemic immune parameters measured from laboratory-infected Atlantic cod and wild infected haddock are discussed. Host immuno-modulation by other arthropod parasites is mediated by pharmacologically active secretions produced by exocrine glands. Therefore, the exocrine glands of the infective and fully metamorphosed female L. branchialis were also investigated in order to identify those that might be responsible for the secretion of host-modifying products. Adult female exocrine glands were mapped using diaminobenzidine (DAB), most commonly known to stain peroxidases and catalases. These compounds are known to be involved in the neutralisation of harmful free radicals which are released during the respiratory burst and tissue damage. Such products may therefore be important protective secretory components at the site of feeding / infection. Exocrine glands were located in the infective stage associated with the oral region, one pair termed the anterior gland complex (AGC), and the other pair extending either side of the oral cone termed the circum-oral glands (CG). These were further investigated using light microscopy and transmission electron microcopy. The AGC and CGs possessed multi-component secretions and they possessed secretory vesicles, abundant and highly active rough endoplasmic reticulum and Golgi apparatus suggesting that protein is an important component of the secretory products. These glands were also observed in the fully metamorphosed females where they had increased in size within the cephalothorax post-metamorphosis. It is hoped that the identification of these glandular structures, which are thought to secrete within the local vicinity of the oral cone, will aid future studies regarding the identification and secretion kinetics of parasite-derived molecules during the infection and feeding process.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-05-04T20:03:01Z No. of bitstreams: 1 2014 - Cl?udia da Silveira de S?o Sabas.pdf: 2854723 bytes, checksum: 72c0b891175db64f709341d091e509e2 (MD5) / Made available in DSpace on 2018-05-04T20:03:01Z (GMT). No. of bitstreams: 1 2014 - Cl?udia da Silveira de S?o Sabas.pdf: 2854723 bytes, checksum: 72c0b891175db64f709341d091e509e2 (MD5) Previous issue date: 2014-02-28 / CAPES / CNPq / Specimens of Conorhynchos conirostris (Valenciennes, 1840), Duopalatinus emarginatus (Valenciennes, 1840), Pimelodus pohli Ribeiro & Lucena, 2006 and Cephalosilurus fowleri (Haseman, 1911) endemic fishes the river S?o Francisco, were collected from the upper S?o Francisco River, Minas Gerais, downstream from the Tr?s Marias Dam (18 ? 12'32'' S and 45 ? 15'41''W), from April 2008 to January , 2012. Twenty three species of parasites were found: Demidospermus uncusvalidus, Scleroductus sp., Pavanelliella pavanellii, metacercariae Austrodiplostomum compactum, Creptotrema creptorema, Crepidostomum platense, Iheringtrema iheringi, Karipharynx sp. Prosthenhystera obesa, metacestodes and plerocercodes of Proteocephalidea, Contracaecum sp. Cucullanus sp. Hysterothylacium sp., Procamallanus (Spirocamallanus) sp1., Procamallanus pimelodus larvae, adults of Cucullanus caballeroi, Cucullanus zungaro, Goezia brevicaeca, Procamallanus (S.) sp2., P. freitasi, Paracapillaria rhamdiae, Philometra sp. and Neoechinorhynchus pimelodi. The host sex did not influence parasite indexes. The total length and weight of the hosts had some influence on the parasite indexes. Parasite communities of C. conirostris, D. emarginatus, P. pohli and C. fowleri were characterized by a low number of central species and few significant interspecific associations. Austrodiplostomum compactum, Contracaecum sp. and N. pimelodi were common on parasite communities of four hosts studied. The parasitics communities of these siluriformes were analyzed in first time with the exception of C. conirostris. Iheringtrema iheringi, Kalipharynx sp., C. caballeroi, G. brevicaeca and P. rhamdiae constitute new records for the S?o Francisco River, expanding their geographic distributions and their host?s lists. / Esp?cimes de Conorhynchos conirostris (Valenciennes, 1840), Duopalatinus emarginatus (Valenciennes, 1840), Pimelodus pohli Ribeiro & Lucena, 2006 e Cephalosilurus fowleri Haseman, 1911, peixes end?micos do rio S?o Francisco, foram coletados da regi?o do alto rio S?o Francisco, Minas Gerais, ? jusante da barragem de Tr?s Marias (18?12?32??S e 45?15?41??W), no per?odo de abril de 2008 a janeiro de 2012. Foram encontradas 23 esp?cies de parasitos: Demidospermus uncusvalidus, Scleroductus sp., Pavanelliella pavanellii, metacerc?rias de Austrodiplostomum compactum, Creptotrema creptorema, Crepidostomum platense, Iheringtrema iheringi, Karipharynx sp. Prosthenhystera obesa, metacest?ides e plerocerc?ides de Proteocephalidea, larvas de Contracaecum sp. Cucullanus sp. Hysterothylacium sp., Procamallanus (Spirocamallanus) sp1., Procamallanus pimelodus, adultos de Cucullanus caballeroi, Cucullanus zungaro, Goezia brevicaeca, Procamallanus (S.) sp2., P. freitasi, Paracapillaria rhamdiae, Philometra sp. e Neoechinorhynchus pimelodi. O sexo dos hospedeiros n?o influenciou os ?ndices parasit?rios. O comprimento e o peso dos hospedeiros tiveram influ?ncia sobre os ?ndices parasit?rios. As comunidades parasit?rias de C. conirostris, D. emarginatus, P. pohli e C. fowleri foram caracterizadas pelo baixo n?mero de esp?cies centrais e poucas associa??es interespec?ficas significativas. Austrodiplostomum compactum, Contracaecum sp. e N. pimelodi foram comuns ?s comunidades parasit?rias dos quatro hospedeiros estudados. ? a primeira vez que as comunidades parasit?rias desses siluriformes s?o analisadas com exce??o de C. conirostris. Iheringtrema iheringi, Kalipharynx sp., C. caballeroi, G. brevicaeca e P. rhamdiae constituem-se novos registros para o rio S?o Francisco, ampliando suas distribui??es geogr?ficas.

The study investigated biological and ecological parameters controlling and influencing the production and distribution of the free-swimming larval stages of Lepeophtheirus salmonis (Kroyer, 1838), and to a lesser extent Caligus elongatus Nordmann 1832, in the natural environment The reproductive output of L. salmonis was influenced by seasonal effects. The number of eggs produced per brood showed an inverse relationship with increasing temperature. The number of eggs per brood was also influenced by adult female body size (cephalothorax length), which in itself exhibited an inverse relationship with increasing temperature. Photoperiod had no significant effect upon the number of eggs produced or on adult female size. Mean egg size of L. salmonis varied significantly over the year; larger eggs were produced during the summer months and smaller eggs over the winter. However, factors controlling the size of the eggs were not elucidated. The proportion of viable eggs per L. salmonis ovisac remained constant throughout the year. Large variations in egg number per egg string were found in both L. salmonis and C elongatus populations sampled at one point in time. These were attributed in part to phenotypic variation in adult female size and also the number of broods individual females had produced. Egg viability was not correlated with brood size, but mean egg size was related to the number of eggs per brood. Experimental studies indicated that hatching and development of L. salmonis was highly variable. The percentage of eggs hatched and the time period over which hatching occurred varied markedly, even when held under constant and optimal environmental conditions. Temperature did not affect hatching success or viability of the nauplius I stage, although at higher temperatures the period over which hatching occurred was reduced. Low and medium salinities caused a significant decrease in both hatching success and nauplius viability. Photoperiod had no effect on initiation of hatching. Hatching occurred in a manner similar to that observed in free-living copepods. The nauplii were enclosed by two egg membranes, the outer one bursting within the ovisac, the inner one after the ovisac membrane has split. Swelling of the egg and its subsequent hatching was attributed to osmotic effects, with water being taken up from the external environment. Development was also highly dependent upon both temperature and salinity. At 5'C, nauplius 11 stages failed to enter the moult to the copepodid stage. At 7.5'C, although moulting was initiated, in a large proportion of cases it was not successfully completed. At I O'C, development to the copepodid stage was successful. Nauplii only developed successfully to the copepodid stage at salinities of 25%o or greater. Copepodids raised under optimal conditions then exposed to a range of salinities had a greater salinity tolerance than nauplii. Biochemical analysis of the eggs of L. salmonis revealed that lipids constituted a large proportion of their dry weight. Naupliar stages contained a discrete area containing lipid which decreased in size over time, suggesting that the free-swimming larval stages utilised this as an energy reserve. Rate of depletion was faster in nauplii held at higher temperatures. Longevity, activity and infectivity of the infective stage decreased with age. However, both spontaneous and stimulus dependent activity ceased many hours before death and both activity and longevity were affected by temperature. Infectivity of I day old L. salmonis copepodids was higher than 7 day old larvae, and was considered to be related to the size of the energy reserves. The settlement and distribution pattern of copepodids did not change with age of copepodid, the majority being recorded from the fins. All three L. salmonis free-swimming larval stages demonstrated a &quot;hop and sink&quot; swimming pattern. The velocity and duration of both passive sinking and active swimming was recorded for both nauplii and copepodids. Although greater periods of time were spent passively sinking, the speeds obtained during both upward spontaneous and stimulated swimming meant that a net upward movement of larvae in the water column occurred. At higher temperatures spontaneous swimming activity increased, whilst low salinities caused a cessation of such ability. L. salmonis larvae were positively phototactic and negatively geotactic. As well as their positive responses to light intensity, the nauplius 11 and copepodid stages reacted positively to blue-green spectral wavelengths. Moulting times were relatively short, although the larvae were not able to swim during such periods. No relationship was found between the level of lipid reserves and the overall buoyancy of the larvae. Naupliar stages of both L. salmonis and C. elongalus were obtained from the water column as a result of a plankton sampling programme at a commercial Atlantic salmon farm. No copepodid stages of either species were found. There was no difference in the vertical distribution of the two L. salmonis naupliar stages. Live larvae tended to aggregate between 0 and 5m in depth, with no diurnal vertical migration. Dead nauplii, and those with low lipid reserves, were found deeper in the water column. Naupliar stages, and in particular the first larval stage, were concentrated in number within cages indicating that the cages have a retentive characteristic. A novel control method in the form of a commercially available light lure was tested. Though increasing the numbers of free-living copepods captured, it had no effect on the numbers of L. salmonis naupliar or copepodid stages obtained in plankton samples. The present study has therefore provided valuable data concerning the biology and ecology of the free-swimming larval stages of sea lice, in what was a comparatively poorly understood area.