No description available.

Ph.D. / The Branchiura is a group of ectoparasitic crustaceans which infect mostly fishes. The subclass contains four genera including Argulus, Chonopeltis, Dolops and Dipteropeltis. Despite their reputation as pests our understanding of their biology is meager. In the first part of the study the anatomy and physiology is described. The species studied include Argulus japonicus, Dolops ranarum and Chonopeltis australis. Live specimens of A. japonicus, D. ranarum and Chonopeltis australis were collected, fixed in Todd‟s fixative and processed for transmission electron microscopy. The results gleaned from A. japonicus and D. ranarum indicated that the ultrastructure and physiology of the cells were similar to the digestive epithelia of free-living copepods. The anterior midgut consists of Resorptive cells (R cells) and the enteral diverticula consist of two cell types including R and Fibril cells (F). The R cells contain lipid droplets and F cells contain rough endoplasmic reticulum indicating that the absorption of nutrients and digestion occurs in the anterior midgut and enteral diverticula. The lipid droplets in both species are large in size and number. Blister cells/B cells and R‟ (apostrophe) cells occur in the posterior midgut and are involved in the processing of digestive waste. The results from C. australis were different from A. japonicus and D. ranarum and reveal the possible presence of F/R cells with multiple functions of both absorption and enzyme secretion. The cells contain few lipid droplets and instead contain many hexagonal-shaped crystalline structures that are interpreted to be proteinaceous. The differences in diet are thought to be influenced by morphological differences in the feeding appendages. The second part of the study involved the supraoesophageal ganglion or brain of C. australis. This genus is unique among the Crustacea since the antennules are absent. This trait poses implications regarding the brain morphology since particular parts of the brain impart nerves that innervate certain appendages in arthropods. Specifically the deutocerebrum or midbrain innervates the antennules. A study was conducted to discover whether the antennular nerves were absent. Specimens of C. australis were fixed in AFA, sectioned and stained with Heidenhain‟s AZAN. Results showed that the antennular nerves were absent and the deutocerebrum was smaller in comparison to the other brain segments indicating degeneration. Moreover, C. australis possesses a reduced number of sensory sensilla on its external surface compared to related genera. The loss of antennules does not affect its sensory capabilities in host searching. However, the reduced numbers of sensilla and its feeble swimming capabilities are more likely to reduce its efficiency in host searching.

Between February 1986 and October 1988, 863 amphibians and reptiles were collected in northcentral Texas and examined for coccidial parasites. Thirteen percent of amphibians <26% salamanders, 11% frogs and toads) and 28% of reptiles (54% turtles, 25% snakes) harbored 20 previously described and 16 new species of coccidia; overall prevalence of infection was 176/863 < 20%). Sixteen Ambvstoma texanum were infected with Eimeria ambystomae which represents new host and geographic locality records for the coccidium. Forty anurans were found to be passing coccidia, including Pseudacris streckeri. Bufo valliceos and Gastrophryne olivacea. Four new species of coccidia were described from anurans and include Eimeria flexuosa. E. streckeri. Isospora dellcatus and I_. fraaosum. However, oocysts found in B. v.. valliceps were determined experimentally to represent pseudoparasites. Sixty-eight turtles were infected with coccidia, including Chelvdra serpentina, Kinoeternon flavescens. Pseudemvs texana. Terrapeng ornata and Trachemvs scripta eleoans. Fourteen eimerians (5 of which are described as new species) were found in turtles. The new species from turtles include Eimeria cooteri, E. ornata, E. Btvlosa. E. texana and E. trachemvdis. Interestingly, all 96 lizards examined were negative for coccidia. Fifty-three snakes including 11 colubrids and 1 viperld harbored coccidia of the genera Caryospora. Cryptosporidium. Eimeria and Sarcocystis: prevalence of infection was highest in 3 species of North American water snakes <Nerodia spp.). Seven new species of Eimeria were described from snakes, including E. conanti. E. lnfirmus. E. papillosum. E. rhombifera. E. serpenticola. E. striatula and E. tenuis. There was no preference for coccidia between the sexes of any hosts. Based on limited data from a single anuran host, prevalence was higher during wetter months of spring than in summer. In addition, prevalence was higher in aquatic and semiaquatic snakes than in truly terrestrial species. Preliminary data suggested that using host specificity data of coccidia may be a method of studying host phylogeny and coevolutionary relationships in thamnophiine snakes.

Arctic charr are susceptible to cestodes like Diphyllobothrium dendriticum which are transmitted through the food web. Field studies investigating Arctic charr-Diphyllobothrium relationships often provide little data from which to fully understand Diphyllobothrium transmission or to assess their impact on copepod or fish hosts. Experimental studies may, therefore, be the only direct way to investigate these issues. The research goal of this thesis was to duplicate the D. dendriticum life cycle in the laboratory to investigate parasite development and host specificity, and to apply the experimental data to natural situations. Results indicated that at 10°C, D. dendriticum eggs develop slowly and 65 days are required for complete embryonation. In many Canadian Arctic lakes water temperatures rarely exceed 4°C, and this study has shown that at this temperature embryonation requires several months, necessitating more than one ice-free season for life cycle completion. The results also showed that embryos developed more rapidly and significantly more eggs hatched when incubated with light or aeration, results that were consistent for D. dendriticum originating from Canada and Norway. To continue the life cycle, coracidia must be consumed by suitable copepod hosts. This study showed that although D. dendriticum will infect the European copepods Cyclops scutifer and Eudiaptomus graciloides, prevalence was higher and procercoids developed more rapidly in E. graciloides. These results showed that E. graciloides is a better host for D. dendriticum than is C. scutifer, contradicting published literature. In North America, E. graciloides is not found in lakes containing D. dendriticum and no North American calanoid species have been tested to determine their host suitability to this cestode. This study identified two North American species, Diaptomus minutus and D. leptopus, which are suitable laboratory hosts. D. minutus is almost certainly a natural host for D. den

M.Sc. / Abalone are among the world’s leading shellfish consumed by human populations. Harvesting in California began in the late 1800s from intertidal zones and in the early 1900s wild abalone were collected by diving. Popular demand for abalone products in the Far East then led to extensive harvesting of wild abalone and a drastic decline in population numbers. This problem was overcome to a degree by the development of land-based abalone farms. At these farms it was possible to breed abalone on a large scale. Currently twelve abalone farms operate in South Africa and the estimated production for 2006 was 537 tons of meat, worth R 80 mil. Parasites and diseases pose threats to the production of abalone, especially under farmed conditions, and can cause considerable financial loss. Labyrinthuloides haliotidis, Haplosporidium nelsoni and Terebrasabelle heterouncinata are a few parasites that contribute to the above mentioned problems. Lately, a new protozoan parasite was discovered in the digestive glands of Haliotis midae farmed in the Western Cape Province, during routine health assessments. For the purposes of this dissertation it is designated an unidentified digestive gland parasite (UDP). The aims of this study are thus to undertake a comprehensive literature review of parasites infecting wild and farmed abalone, as well other shellfish species, describe and characterise the UDP infecting the digestive gland of Haliotis midae based on its structure and ultrastructure, evaluate the role of this parasite in disease by analysing data from histological studies, provide a preliminary indication of the life cycle of this parasite, attempt analysis of DNA from the UDP, and identify potential areas for further research into control of the parasite. A total of 180 abalone, (Haliotis midae) were collected from three abalone farms in the Western Cape during May 2005, October 2005, January 2006 and January 2007. To establish whether this parasite also occurs in wild abalone, a single sampling (six H. midae and 28 H. spadicea) took place during 2006 in Tsitsikamma National Park. Collected farmed and wild abalone were weighed and measured, removed from their shells and then killed according to accepted methods before their digestive glands were removed.

No description available.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

The host/parasite association between the pulmonate snail Stagnicola elodes and the digenean Plagiorchis elegans was examined with a view to identifying some of the biotic and abiotic factors that govern parasite egg development, infectivity and survival, the dynamics of cercarial production, as well as host susceptibility to infection, growth, reproduction and mortality. Plagiorchis elegans eggs passed with the feces of the hamster (Mesocricetus auratus) experimental definitive host were unembryonated. Between 0 and 30 C, the rate of embryonation continued to increase with temperature, whereas infectivity and survival were optimal between 10 to 20 C. Light adversely affected embryonation. Parasite acquisition increased with the intensity of exposure and sexual maturity. Infection invariably enhanced pre-patent host growth in a dose-dependent manner. Cercarial production increased with time and reached a plateau. Snails infected prior to sexual maturity released more cercariae than mature individuals. Heavily infected snails tended to die prematurely regardless of age at infection and parasite dose, thereby reducing their total production of cercariae to levels below those of more lightly infected individuals. Even light infections castrated the snail host. Snails infected when immature never reproduced, whereas reproductive snails ceased egg production within days of infection. Similar effects were observed in the incompatible snail host Biomphalaria glabrata, although no cercariae were ever produced. Both enhanced growth and parasitic castration are attributable to the mother sporocyst.

Thèse de doctorat--Sciences naturelles--Faculté des sciences de Paris, 1907. N°: 1276. / Notes bibliogr.

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.