The biology of Secculina carcini, a parasite on the common shore crab, Carcinus maenas, was studied with particular emphasis on larval morphology, biochemical content and energetic demands. The prevalence and distribution of the parasite was also investigated. The field studies carried out on the populations of S. carcini on C. maenas in northern France and North Wales, together with a review of the literature, demonstrated a disparate distribution. The larvae of S. carcini are lecithotrophic and can develop within 5 days to the cyprid and are capable of settlement 2 days later. The highest prevalence for the parasite was observed to correlate with semi-enclosed bodies of water. It is proposed that in this situation, with the short development time, the larvae are retained, thus increasing the probability of successful cypris settlement. Such coastal systems are susceptible to variable conditions, consequently experiments were undertaken to investigate the larval tolerance to temperature and salinity variations. A morphological study was carried out on the naupliar stages of S. carcinl. The typical cirripede limbs were simple and lacked gnathobases. There was also a vestigial ventral thoracic process present in the stage III and stage IV nauplius. These observations supported the argument that the rhizocephalan nauplius fits within the cirripede nauplius form. - ii - The energy budget study, involved the investigation of ash-free dry weights per larva, respirometry for each larval stage and analyses of the biochemical constituents using colorimetric and gravimetric techniques, Finally an equation was developed which demonstrates the energy budget for S. carcini, from the beginning of larval development to settlement on the host and the subsequent metamorphoses to the inoculation stages.

No description available.

Weight-specific oxygen consumption of midgut gland tissue of Hemigrapsus nudus has been investigated at three levels of salinity (35%, 75% and 125% sea water), two levels of experimental temperature (5°C and 20°C) and four acute (Warburg) temperatures (5°, 10°, 15° and 20°C) in all combinations for each season (summer and winter). Metabolic-temperature curves reveal that at standard baseline conditions where the animals are held 24 hr at their respective seasonal temperature and salinity, midgut gland respiration is highest at all acute temperatures in the summer animals. Acutely measured metabolic-temperature curves for midgut gland tissue show that winter animals acclimated to their opposite seasonal conditions of temperature and salinity for 10 days demonstrate the greatest degree of acclimation. The effect of experimental temperature is statistically and biologically significant. The highest respiration rate is at 5°C. Low temperature (5°C) may provide a greater thermal stress than a high temperature (20°C) resulting in a higher rate of oxygen consumption. Experimental temperature also influences the seasonal respiratory response of midgut gland tissue to salinity. In summer animals there is no correlation of midgut gland respiration to salinity at 5°C. There is a increase in respiration rate as the osmotic gradient between the blood and medium increases at the seasonal baseline temperature of 20°C. Winter animals held at the seasonal baseline temperature of 5°C demonstrate a "V-shaped" relationship to salinity with the lowest respiratory response in 75% sea water where the gradient between the blood and medium is minimal. Animals held at 20°C increase respiration with an increase in salinity. It is suggested that the metabolic activity of midgut gland from summer animals may be related to the maintenance of a osmotic gradient between the blood and medium or alternatively to the energy demands associated with new exoskeleton formation. The proposal is put forth that midgut gland respiration in winter animals may indicate osmotic work being done to maintain the osmotic gradient between the blood and medium. The production of a urine hypotonic to the blood may also assist winter animals in regulation of blood electrolytes. The regression coefficients of weight-specific oxygen consumption as a function of body weight were not significantly different from zero at the 0.01 probability level. / Science, Faculty of / Zoology, Department of / Graduate

The effects of initial thermal processing, plant sanitation, and employee habits on the microbiological quality of blue crab (Callinectes sapidus) meat were determined in a commercial crab processing facility. Thermal processing was evaluated at 5, 7, and 8 minutes at 250ï °F for the destruction of microorganisms, including Listeria monocytogenes. F-values calculated indicated a sufficient reduction of L. monocytogenes at each processing time. Fresh picked crab meat was evaluated for microbial levels when exposed to ambient temperatures over a four hour period. It was found that time and temperature did not influence the microbial populations significantly except in the fourth hour. Plant sanitation was evaluated based on levels of adenosine triphosphate (ATP) and microbial counts. Areas found to have high levels of ATP typically had low microbial counts, thus suggesting that crab meat residual was the problem. The presence of Listeria species in the plant was determined using a commercial polyclonal antibody test. Listeria species were found under picking tables, on cooler doors, employees' aprons, and on several employees' hands. In a laboratory setting, an automated hand wash was compared with a manual hand wash for the removal of Listeria innocua, as a model for Listeria monocytogenes. It was found that a manual hand wash of 15 seconds was superior to an equal time automated wash. The microbial quality of crab meat was found to be affected by daily plant procedures, and could be changed by modifying procedures. / Master of Science

A structural analysis of the compound eye of Hemigrapsus nudus expands the basis of functional analysis of decapod Crustacean eyes. Contradictory evidence for disintegration of rhabdomeric microvilli in the absence of light prompted observation of H. nudus eyes after 146 days in darkness. Eyes were fixed with formalin and glutaraldehyde and post fixed with osmium tetroxide for electron and light microscopy. Light- dark-adapted eyes were also observed with hot water fixation and paraffin embedment. The eye of H. nudus is typical of decapod Crustacean compound eyes. Corneagenous cells underlie the transparent cuticle cone cells secrete the composite crystalline cone which contacts the rhabdom proximally. The single fused rhabdom is composed of layers of microvilli from two groups of retinular cells. The layers are oriented at right angles to each other, and perpendicular to the optic axis of the ommatidium. A presumptive four-lobed eighth retinular cell makes up the distal end of the rhabdom. Distal, proximal and reflecting retinal pigments are located in the distal pigment cells, retinular cells and tapetal cells, respectively. Distal and proximal pigments surround the rhabdom during light-adaptation, and withdraw during dark-adaptation. Reflecting pigment is found above the basement membrane in light-adapted eyes and below it in dark-adapted eyes. The crystalline cone may change length during light- and dark-adaptation. Prolonged darkness does not cause disintegration of the rhabdomeric microvilli. H. nudus lives in conditions of dim illumination. The fused, layered rhabdom is an efficient mechanism of light absorption. Internal reflection within the rhabdom is enhanced by the palisade and further increases light absorption. Functional units exist within the ommatidium. Mutually perpendicular rhabdomeric layers suggest intraretinal polarized light perception. Eighth retinular cells may respond individually to light focused on the distal rhabdom by the dioptric apparatus in mosaic image formation.

Thesis (M.M.S.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 85-91.

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves [52]-55).

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : [39]-42).

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : 27-28).

Graduation date: 1968