Thesis (M.A. in Security Studies (Civil Military Relations))--Naval Postgraduate School, March 2004. / Thesis advisor(s): Donald Abenheim. Includes bibliographical references (p. 85-93). Also available online.

No description available.

It has been demonstrated that nitrogen fixation is a source of hydrogen (H2) to the ocean and therefore measurements of H2 concentrations may be used as a possible indicator of nitrogen fixation (Moore, Punshon, Mahaffey, & Karl, 2009). However, the limited number and sparse distribution of measurements of dissolved hydrogen and nitrogen fixation rates made in the open ocean in the past have made it difficult to quantify the relationship between them. Toward this end, a new method of equilibrating seawater samples for H2 measurement was employed along the 13,000 km Atlantic Meridional Transect (AMT20) from UK to Chile, allowing H¬2 to be measured from underway samples every 3.5 minutes and thereby considerably increasing the number and resolution of H2 measurements made in the open ocean.These high-resolution measurements reveal two regions with high H¬2 concentrations, one in the North Atlantic and one in the South Atlantic.

No description available.

The buoyancy (or density = mass volume-1) of marine larval fish is influenced by their nutritional status, starved larvae being less dense than fed larvae of like age. Buoyancy has, therefore, been proposed as an indicator by which to assess the nutritional condition of marine fish larvae in experiments and in situ. It has also been hypothesized that larval fish experiencing advanced starvation will exhibit increased density due to water loss resulting from osmoregulatory breach and failure. The magnitude of osmoregulation-related changes in density has not been examined and its influence on interpretations of nutritional condition and vertical distributions are unknown. Through a series of controlled laboratory experiments performed on larvae of cod (Gadus morhua L.), I developed evidence that osmoregulatory breach and failure has a strong positive effect on the density of larval fish, and that this effect on density is not limited to larvae experiencing advanced stages of starvation. These effects of osmotic breach and failure are sufficient to obscure effects resulting exclusively from nutritionally caused changes in density. Hence, if not identified and controlled these osmotically driven density changes can bias parameterization of buoyancy-related condition indices. I developed methods for isolating nutritional and osmotic effects. This facilitated the calibration of a nutritionally based density index with which to evaluate the nutritional state of cod larvae. Comparison of the calibrated density assay with a suite of widely used indices of condition (morphometric, behavioural and biochemical) showed density to be superior in its capacity to correctly classify larvae with respect to their nutritional state. The density index was also less subject to bias resulting from uncontrolled changes in larval size. A linear regression model based on these findings was developed to assess the relationship between density as an index of condition and near-term larval

Salmon catch data wee analysed from fisheries in or around the mouths of some rivers on the east coast of Scotland spanning the period from the late eighteenth century to the 1980s. It was found that the numbers and sea-age composition of salmon caught and the time of year that salmon were caught varied in the long-term in a coincident manner in different fisheries. These coincident changes in salmon catch data could not be explained by changes in the operation of fisheries and were therefore the results of changes in the population of salmon returning to the Scottish coast. The observed changes in salmon population parameters often coincided with known hydrobiological events in the North Atlantic area, but simple consistent associations between hydrobiological changes and changes in salmon populations were not found. It was concluded that salmon populations were influenced by marine factors but that relationships may be complex. Since there may be several different mechanisms which can cause changes in the sea-age and time of return of salmon, it is not to be expected that a simple causative relationship should be found. The characteristics of salmon which were caught spawning in different burns within the River North Esk system during the winters of 1989/90 and 1990/91 were analysed. It was found that those fish which spawned furthest upstream tended to have a higher sea-age and smolt-age, a smaller length and entered the river earlier in the year than would have been expected if fish entering the North Esk at different times of the year spawned randomly throughout the North Esk system. Likewise those fish which spawned further downstream tended to be large (for their sea-age), had a low sea-age and smolt-age and entered the North Esk late in the year. Although less strong evidence was obtained, a similar pattern was observed for fish which spawned at different times within the spawning season. Those fish which spawned earliest (late October/early November) tended to have entered the river earliest in the year. Analysis of environmental conditions in different burns during the spawning season of 1990/91 suggested that fish which entered the North Esk at different times of year selected particular tributaries to spawn in - the segregation observed was not the result of the chance occurrence of environmental conditions which were conducive to spawning at different times of the year in different burns. The smolt-ages of the adult fish caught in each burn were similar to that of juvenile fish in each respective burn. This suggests that adult fish were returning to the part of the river system in which they were born. Time of return to freshwater and time of spawning were concluded to be adaptations to different environments within the North Esk system. However these characteristics may not be rigorously important and the constitution of a sub-population may alter as a result of selection processes perhaps in the sea.

Graduation date: 1981

Thesis (Ph.D.)--Ohio University, August, 2008. / Release of full electronic text on OhioLINK has been delayed until August 1, 2011. Includes bibliographical references (leaves 325-346)

Thesis (Ph.D.)--Ohio University, August, 2008. / Title from PDF t.p. Release of full electronic text on OhioLINK has been delayed until August 1, 2011. Includes bibliographical references (leaves 325-346)

Mémoire (M.Ress.Renouv.)--Université du Québec à Chicoutimi, 1997. / Document électronique également accessible en format PDF. CaQCU