Thesis (Ph.D.)--York University, 2008. Graduate Programme in Sociology. / Typescript. Includes bibliographical references (leaves 295-327). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR39015

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M.Sc. / Please refer to full text to view abstract

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<p> Members of a Californian species of Artemia were raised in brines of four different specific gravities, (1.028, 1.062, 1.090, and 1.120), with the other environmental factors held as constant as possible. Three populations of the shrimp (1.028, 1.090, and 1.120) followed a typical growth curve, while the fourth group (1.062) did not. The dimensions of the mature specimens could be related to the specific gravities of their environments by a formula of the general form y = ax + b </p> <p> These results were, SPECIFIC GRAVITY= 1.19 - .359(±.018)WTHCAF - .067(±.010)LTHSTE +.012(±.003)ABDLTH +.097(±.032)DEPTHU for a mature population.</p> <p> An inverse relationship between biomass and specific gravity was determined as was a direct relation between specific gravity of the media, and inorganic residue left after the organic material of the shrimp had been burnt away.</p> / Thesis / Bachelor of Science (BSc)

The mantis shrimp Gonodactylus oerstedii is known to possess eyes capable of colour and polarised light vision. The apposition compound eyes of these creatures are highly mobile and their ommatidia are specialised to analyse the spectral and e-vector qualities of light in a central strip of the eye called the midband. The retina of the midband of Rows 1-4 is tiered with each row being sensitive to a narrow region of the colour spectrum. Row 5 and 6 ommatidia possess many structural features designed to allow the e-vector direction of light to be detected. This thesis investigates the neuroanatomy in the neuropile regions below the retina in an attempt to elucidate the mechanisms which allow colour and polarised light vision to take place. In Chapter 2 the retina-lamina projection of the retinal axons is studied in an ommatidium in Row 3 of the midband, and the findings suggest that the stomatopod is similar to all other crustacea so far studied, despite its unusual retina. Chapter 3 investigates the neuroanatomy of the medulla neuropile regions. A novel region of the medulla externa which deals with colour information is discovered. In Chapter 4 the lamina of Rows 1-4 is looked at in more detail, with the number of monopolar cells and the detailed arrangements of the retinular cell terminals being ascertained. The terminals sensitive to different regions of the spectrum are located in different areas of the lamina cartridge. Chapter 5 looks at many of the issues above but this time in relation to rows 5 and 6 of the midband, which are specialised for polarisation vision. The lamina neuropile is very different to that of Rows 1-4 and again a specialised region of the medulla externa is found which processes information from these rows. This thesis provides evidence that the optic lobes of Gonodactylus oerstedii are comparable to other crustacea but nevertheless may possess some intriguing specialisations related to their extraordinary colour and polarised light vision.

Taura syndrome (TS) is one of the most devastating diseases affecting the shrimp farming industry worldwide. The causative virus, Taura syndrome virus (TSV), has been identified. My work is centred on the development of monoclonal antibodies against TSV. I have also characterized a novel variant of the virus from Venezuela and evaluated the effect of hyperthermia on TSV infection. This work has resulted in 3 manuscripts, which constitute the core of this dissertation. The taxonomy throughout this dissertation is done according to Holthuis (1980).The first manuscript describes the production of a monoclonal antibody reacting with the Belize strain of TSV. The antibody, MAb 2C4, exhibits good sensitivity and specificity for TSV in immunohistochemistry (IHC) and dot blot immunoassay. MAb 2C4 reacted with the TSV-HI94, TSV-SI98 and TSV-BZ02 variants, but not with the TSV-VE05 and TSV-TH05 variants. This antibody adds and improves tools to those available for TSV diagnosis.Chapter three describes a relatively novel variant of TSV from Venezuela, which was characterized by our laboratory. By genetic sequencing, this new isolate exhibits a 94% similarity with TSV-HI94. IHC, dot blot immunoassay and bioassays were also performed. While processed samples reacted only weakly with the TSV monoclonal antibody MAb 1A1, the virus in its native state reacted strongly with the antibody. In bioassays, TSV-VE05 presented mortality comparable to TSV-HI94 in Penaeus vannamei. These data confirm the presence of TSV in Venezuela and that a new variant of the virus was responsible for the outbreak of TS.In chapter four, the behavior of TSV infection under hyperthermic conditions was examined. I compared the susceptibility of Kona stock P. vannamei to the infection by two variants of TSV under hyperthermic conditions (32oC). Shrimp, infected with TSV-HI94, were resistant to infection at high temperature. However, under the same hyperthermic conditions, the challenged shrimp were fully susceptible to the infection by TSV-BZ02. This susceptibility to TSV-BZ02 at higher temperatures was independent both of the route of infection and of the salinity of water. I conjecture that TSV-BZ02 might be a temperature permissible mutant of TSV.

Yucca (Yucca schidigera) and Soapbark (Quillaja saponaria), both native desert plants, are major commercial sources of saponin extracts. Yucca schidigera is native to the southwestern United States and to the arid Mexican desert, and Quillaja saponaria is found in arid areas of Chile. Saponins have detergent or surfactant properties with both water-soluble and fat-soluble components.The use of natural saponins from yucca and soapbark as an additive in the diet, has improved production in aquatic organisms. The purpose of this study was to evaluate the effect of inclusion of Nutrafito plus (NTF+), which is a mixture of Yucca and Soapbark extracts, on growth, survival, and development of Nile tilapia Oreochromis niloticus and the effect on growth, survival, development, and digestive enzyme activities for juvenile Pacific white shrimp Litopenaeus vannamei.The extracts were included at different levels in the diets of tilapia and shrimp in four experiments. In experiment 1, at the end of 6 weeks there was no significant difference (p > 0.05) between growth rates of tilapia fed 6 different diets, with no mortality nor abnormal behavior in any of the treatments. Water quality parameters were determined weekly and remained within recommended limits for Nile tilapia culture.In the second trial, at the end of 40 days, there was no significant difference (p > 0.05) between growth rates of fish fed 7 different diets with various levels of Nutrafito. There were no mortalities during the experiment.In the third trial, 20 tanks (140 L each) were stocked with 10 shrimp each. Tanks were divided into 5 treatments with 4 replicates each. There was significant difference (p < 0.05) between growth rates of shrimp fed 5 different diets, with higher growth rate at higher levels of inclusion.In the fourth trial, 15 tanks (140 L each) were stocked with 10 shrimp each. Tanks were divided into 5 treatments with 3 replicates each. There was significant difference between growth rates and feed conversion ratio of shrimp fed 5 different diets. In addition, an analysis for digestive enzymes activity was done and no significant difference (p > 0.05) was found between treatments.

A series of studies were conducted as part of my dissertation research on certain diseases of farmed penaeid shrimp and on strategies that might be applied to manage these diseases. These studies focused on the development and application of management for four shrimp diseases (TSV, YHV, WSSV and NHP) in the white shrimp Penaeus vannamei through different strategies. The studies focused on efforts to identify a new strain of Taura syndrome virus (TSV), and the prevention or mitigation of infection by Yellow Head Disease (YHD), White Spot Disease (WSD), and Necrotizing Hepatopancreatitis (NHP). The new strain of TSV reported in this study is among the most pathogenic strains discovered to date. Disease management strategies investigated include the prevention of YHD in the Americas by pre-exposing Specific-Pathogen-Free (SPF) Penaeus vannamei to TSV. The other strategy investigated involved the use of a prototype "vaccine" that binds to the specific shrimp cell receptors and thus, prevents WSSV from establishing an infection. The last strategy attempted to elucidate the reasons for the very low prevalence of NHP in commercial shrimp ponds in Colombia. It was found that through establishment of a breeding program in which shrimp were selected for resistance to TSV infection, Colombian shrimp farmers also, but indirectly, selected for resistance to NHP.