This study consisted of several experiments designed to compare the ability of two species of fungi, Saprolegnia ferax and S. parasitica to grow on two species of fish, smallmouth bass (Micropterus dolomieui) and goldfish (Carassius auratus), and to determine the criteria necessary for the development of these infections. The results indicate that water in the fish tanks must be slightly acid (pH 6), warm (22°C), nonmoving, and that the fish must be wounded in order for fungal infection to occur. Cool water (18°C) and moving water, caused by aeration and filtration, are detrimental to fungal colony formation so that no infection occurs. Both S. ferax and S. parasitica infected both species of fish, on an average of three days after innoculation. The S. ferax infected a higher percentage of both fishes than did the S. parasitica. The difference in susceptibility of the two fish species to the fungi was negligible.

To date there has been only on major study concerned with parasites of freshwater fishes of California. E. C. Haderlie (1953) summarized investigations up to that year and conducted a general survey of the monogenetic and digenetic trematodes, cestodes, nematodes, acanthocephalans, copepods, and hirudinians of fishes of Northern California. From 2010 fishes representing 36 species of 11 families examined over a three-year period, he obtained a total of 59 species of helminth parasites, copepods, and hirudinians, which include 20 species of digenea and 16 species of cestodes. In addition to the taxonomic study, Haderlie attempted to correlate the relative occurrence of the parasites with various ecological habitats. These data are incomplete, except for a general ecological discussion of the parasites taken from Clear Lake and its contributing streams. In the Sacramento-San Joaquin area the monogenetic trematodes are the only group that has been extensively studied. This work has been done by Dr. J. D. Mizelle of Sacramento State College. The primary purpose of the current investigation is to gain some knowledge of the species of endoparasites of fishes of the San Joaquin Delta. Two hundred and thirty sic fish were examined, including diadromous, potamodramous, anandromous, and territorial species of San Joaquin Delta. This has resulted in the recovery of two previously described and one new adult digenea, three metacercariae, two adult and three larval cestodes,and two cestodarians. Not included in this study are the Acanthocephala and Nematoda. A few cestodes are also not included because of their poor condition. The Host-Parasite List (p. 49) of this paper gives a summary of the fishes examined by Haderlie (H) and the present author (E) with the number of each species examined and the species of trematodes and cestodes recovered.

six species of gyliauchenids are reported in this study, five in the genus Gyliauchen and one in Apharyngogyliauchen. G. pomacentri n.sp. is described from a single specimen recovered from one of one Pomacentrus philippinus, G. parapapillatus n.sp. is described from 42 specimens in one of one Siganus virgatus. Gyliauchen zancli n.sp. is described from a single specimen in one of one Zanclus cornutus. Gyliauchen nahaensis Ozaki, 1937 is redescribed from 189 specimens in one of two siganus punctatus and establishes a new locality record, and in one of one zanclas cornutus, a new host record. Gyliauchen sp. is described from two specimens of two of four Siganus spinus.

D.Phil. (Zoology) / Fish parasites may cause disease and lead to commercial losses. In order to construct practical management systems to mitigate or manage potential adverse effects, information on basic biological variables is required. Compared to the number of internationally published papers on the subject, little is known about the monogenean parasite fauna of South African fishes. Monogeneans are largely ectoparasitic, thin, flattened, host- and site specific parasites with a simple life cycle involving a single host (often a fish). They range in size between 0.3 mm and 20 mm and are mostly bilaterally symmetrical with the body subdivided into a number of regions. Attachment organs are a necessary feature both anteriorly and posteriorly, with the morphology of the prominent posterior attachment organ (opisthaptor) highly variable between genera. It may contain suckers, clamps or large hooks (anchors) as well as marginal hooks. In some genera anchors (one to two pairs) are associated with spikes or accessory sclerites and are supported by a connecting bar. All these structures, together with the sclerotized male copulatory organ, are of taxonomic significance....

Trygonorrhina fasciata (Rhinobatidae) specimens naturally infected by three monogenean species were captured and maintained in marine aquaria to promote a continuous parasite load. Monogenean eggs recovered from aquaria provided larvae for descriptions and life history experiments. I describe the adult, larva and post-larval development of a new species of hexabothriid, Branchotenthes octohamatus, from the gills. This is the first monogenean larva described with only eight hooklets. This character may be useful to help resolve problematic relationships within the Hexabothriidae and offers insight into more general hypotheses about relationships within the Monogenea. I also redescribe the adult of Calicotyle australis (Monocotylidae) from the cloaca and describe the larva. The number and arrangement of larval ciliated epidermal cells and sensilla was revealed using silver nitrate. I redescribe Pseudoleptobothrium aptychotremae (Microbothriidae) adults from the skin of T. fasciata, representing a new host and locality record. Larval anatomy and post-larval development are also documented. The presence of six needle-like spicules in the larval haptor is confirmed, supporting an earlier theory that spicules are ancestral vestiges. My studies revealed three different egg hatching, host finding strategies and larval ‘types’. Branchotenthes octohamatus has a ‘sit-and-wait’ strategy, entirely dependent on mechanical disturbance to stimulate eggs to hatch. Larvae are unciliated, cannot swim, lack pigmented eyespots and show no photo-response but may survive for more than two days after hatching at 22ºC. In contrast, eggs of C. australis hatch spontaneously with a strong diurnal rhythm in the first few hours of daylight when exposed to a LD12:12 illumination regime. Larvae are ciliated and can swim, have pigmented eyespots, are photo-positive and can remain active and survive for up to 24 h after hatching at 22ºC. Eggs of P. aptychotremae may have a ‘bet-hedging’ strategy. Some eggs hatch spontaneously and rhythmically in an LD12:12 regime during the last few hours of daylight but their low hatching success rate suggests that other eggs may require a different cue provided by the host. Larvae are ciliated, can swim, lack pigmented eyespots, show no photo-response and remain active for only a few hours at 22ºC. Experiments using the fluorescent dye, 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE) revealed B. octohamatus on gills of T. fasciata within 30 min of exposure to the host. This provides strong evidence that larvae invade the gills directly via the host’s inhalant respiratory current and do not migrate after initial attachment elsewhere. Five rhinobatid species (Aptychotrema vincentiana, T. fasciata, Trygonorrhina sp. A, A. rostrata and Rhinobatos typus), with overlapping distributions spanning west, south and east Australian coastal waters were surveyed for monogeneans at four locations between Fremantle, Western Australia and Stradbroke Island, Queensland. Genetic homogeneity, using the mitochrondrial gene Cytochrome b (cytb) and the nuclear marker, Elongation factor-1 alpha (EF1a), was observed for all Branchotenthes and Calicotyle specimens irrespective of collection locality or rhinobatid species. Genetic homogeneity was observed for Pseudoleptobothrium specimens collected in western and southern Australia. However, local genetic heterogeneity was apparent among Pseudoleptobothrium specimens collected from two sympatric host species in New South Wales. Analyses revealed a highly divergent clade, indicating a morphologically cryptic, ancestral species. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1323070 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Trygonorrhina fasciata (Rhinobatidae) specimens naturally infected by three monogenean species were captured and maintained in marine aquaria to promote a continuous parasite load. Monogenean eggs recovered from aquaria provided larvae for descriptions and life history experiments. I describe the adult, larva and post-larval development of a new species of hexabothriid, Branchotenthes octohamatus, from the gills. This is the first monogenean larva described with only eight hooklets. This character may be useful to help resolve problematic relationships within the Hexabothriidae and offers insight into more general hypotheses about relationships within the Monogenea. I also redescribe the adult of Calicotyle australis (Monocotylidae) from the cloaca and describe the larva. The number and arrangement of larval ciliated epidermal cells and sensilla was revealed using silver nitrate. I redescribe Pseudoleptobothrium aptychotremae (Microbothriidae) adults from the skin of T. fasciata, representing a new host and locality record. Larval anatomy and post-larval development are also documented. The presence of six needle-like spicules in the larval haptor is confirmed, supporting an earlier theory that spicules are ancestral vestiges. My studies revealed three different egg hatching, host finding strategies and larval ‘types’. Branchotenthes octohamatus has a ‘sit-and-wait’ strategy, entirely dependent on mechanical disturbance to stimulate eggs to hatch. Larvae are unciliated, cannot swim, lack pigmented eyespots and show no photo-response but may survive for more than two days after hatching at 22ºC. In contrast, eggs of C. australis hatch spontaneously with a strong diurnal rhythm in the first few hours of daylight when exposed to a LD12:12 illumination regime. Larvae are ciliated and can swim, have pigmented eyespots, are photo-positive and can remain active and survive for up to 24 h after hatching at 22ºC. Eggs of P. aptychotremae may have a ‘bet-hedging’ strategy. Some eggs hatch spontaneously and rhythmically in an LD12:12 regime during the last few hours of daylight but their low hatching success rate suggests that other eggs may require a different cue provided by the host. Larvae are ciliated, can swim, lack pigmented eyespots, show no photo-response and remain active for only a few hours at 22ºC. Experiments using the fluorescent dye, 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE) revealed B. octohamatus on gills of T. fasciata within 30 min of exposure to the host. This provides strong evidence that larvae invade the gills directly via the host’s inhalant respiratory current and do not migrate after initial attachment elsewhere. Five rhinobatid species (Aptychotrema vincentiana, T. fasciata, Trygonorrhina sp. A, A. rostrata and Rhinobatos typus), with overlapping distributions spanning west, south and east Australian coastal waters were surveyed for monogeneans at four locations between Fremantle, Western Australia and Stradbroke Island, Queensland. Genetic homogeneity, using the mitochrondrial gene Cytochrome b (cytb) and the nuclear marker, Elongation factor-1 alpha (EF1a), was observed for all Branchotenthes and Calicotyle specimens irrespective of collection locality or rhinobatid species. Genetic homogeneity was observed for Pseudoleptobothrium specimens collected in western and southern Australia. However, local genetic heterogeneity was apparent among Pseudoleptobothrium specimens collected from two sympatric host species in New South Wales. Analyses revealed a highly divergent clade, indicating a morphologically cryptic, ancestral species. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1323070 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

This thesis presents an investigation into Gyrodactylus species recognition, making use of machine learning classification and feature selection techniques, and explores image feature extraction to demonstrate proof of concept for an envisaged rapid, consistent and secure initial identification of pathogens by field workers and non-expert users. The design of the proposed cognitively inspired framework is able to provide confident discrimination recognition from its non-pathogenic congeners, which is sought in order to assist diagnostics during periods of a suspected outbreak. Accurate identification of pathogens is a key to their control in an aquaculture context and the monogenean worm genus Gyrodactylus provides an ideal test-bed for the selected techniques. In the proposed algorithm, the concept of classification using a single model is extended to include more than one model. In classifying multiple species of Gyrodactylus, experiments using 557 specimens of nine different species, two classifiers and three feature sets were performed. To combine these models, an ensemble based majority voting approach has been adopted. Experimental results with a database of Gyrodactylus species show the superior performance of the ensemble system. Comparison with single classification approaches indicates that the proposed framework produces a marked improvement in classification performance. The second contribution of this thesis is the exploration of image processing techniques. Active Shape Model (ASM) and Complex Network methods are applied to images of the attachment hooks of several species of Gyrodactylus to classify each species according to their true species type. ASM is used to provide landmark points to segment the contour of the image, while the Complex Network model is used to extract the information from the contour of an image. The current system aims to confidently classify species, which is notifiable pathogen of Atlantic salmon, to their true class with high degree of accuracy. Finally, some concluding remarks are made along with proposal for future work.

M.Sc. (Zoology) / 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. 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.

Lernaea spp. was identified as a widespread problem in West Malaysia and various aspects of the parasite were studied. A survey of the distribution of Lernaea spp. in West Malaysia revealed its presence in all the 8 government owned fish breeding stations, 104 privately owned farms and 4 out of 5 consignments of imported fingerlings. The Lernaea spp. present in these ponds were identified as L. piscinae and L. cyprinacea "Asian" form (=b.elegans) and its morpha forms, L. ctenopharyngodonis and L.guadrinucifera. The life cycles of L. cyprinacea and L. piscinae were determined under laboratory conditions. Infection of ~. auratus with the offspring of L. cyprinacea "Asian" form produced adult females similar to the maternal form and another form identified as b. ctenopharyngodonis. A. nobilis, infected with L. cyprinacea "Asian" form and L. piscinae produced only species identical to the maternal form. A high degree of polymorphism was revealed and was further investigated. Morphometric studies on the larval stages and adult female parasites were investigated and reliable characteristics for the identification of Lernaea is discussed. The distribution frequency of b. cyprinacea on 3 host species and L. piscinae on A. nobilis in aquarium tanks was goodness of tested for/fit with the theoretical negative binomial distribution. The bases of fins were found to be the preferred site of infection for both species. studies on growth performance of A. nobilis infected with L. piscinae in ponds, revealed a significant reduction in Specific Growth Rates. Infected fish had a higher mortality than uninfected fish. A decrease in parasite infection on the body surface after 3 months was associated with its appearance in the eye. A challenge infection did not establish and the fish were suspected of being immune. Histopathological studies showed a typical inflammatory response with the formation of a granuloma. Eosinophilic granular cells, lymphocytes, and club cells which were identified in the hosts immune to the infection, were believed to play an important role in the rejection of parasites.

No description available.