Thesis (Ph. D.)--University of Chicago, Dept. of Ecology and Evolution, August 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliography.

Thesis (M.S.)--Oregon State University, 1980. / Includes bibliographical references (leaves 180-192). Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 200-215). Available also in a digital version from Dissertation Abstracts.

vi, 58 p. ; ill., maps. A print copy of this title is available from the Oregon Institute of Marine Biology library, under the call number OIMB QL391.A6 W5. / The tube hood orientation of Pista pacifica is non-random and related to current direction. Results from field measurements and from one flow tank experiment suggest that Pista pacifica build their tube hoods at right angles to local currents, and perhaps away from the direction of any sediment transport which may occur normal to the prevalent current direction. By orienting their tube hoods perpendicular to water currents, the animals may be making use of the kinetic energy of the water motion around them to generate a tube ventilation current. This current may in turn lessen the energetic needs of the worms by providing internal ventilation and sediment flushing currents at little energetic cost to the organism. / Adviser: Robert C. Terwilliger

THE THESIS This thesis describes the investigation of an estuarine front, the 'tidal-intrusion front, which was initially found in the Seiont estuary, North Wales but has subsequently been observed at other locations. In the Seiont, the front forms after low water, moves a considerable distance into the estuary to an upstream limit, retreats from the estuary and finally weakens, all within the duration of the flooding tide. It separates mixed from stratified regimes and is characterised by its surface appearance; inside the estuary, the front is 'V'-shaped with its apex directed towards the estuary head. Associated convergent flows include collection of all surface buoyant material at the apex of the V. Following a considerable field investigation of the front in the Seiont, two short periods were spent studying a similar feature in Loch Creran, Scotland. In the process of investigating other sites to determine the range of estuarine parameters appropriate to a stable tidal-intrusion front, an alternative estuarine convergence was discovered in the Conwy estuary, North Wales. The Conwy shows similar frontal behaviour to the Seiont during the early part of the flood tidal phase, but increased flood currents subsequently break down stratification producing an estuary of the 'well-mixed' class. 5 Throughout the remainder of the flood tide an axial line of debris forms along a substantial proportion of the estuary length. The persistence of the line indicates a secondary circulation which includes surface convergence towards the estuary axis. However, the line disperses at high water and no similar system is apparent during the ebb. The specific aims of the thesis may be summarised with respect to: a) the tidal-intrusion or T.I. front; i) to understand the parameters which govern the movements of the front. ii) to explain and/or reproduce by modelling, the three-dimensional aspects of the 'V'-shaped frontal boundary. b) the axial convergence or A.C. i) to detrmine the nature of the secondary circulation in the Conwy i.e. the pattern of cross-sectional secondary velocities. ii) to determine a mechanism which accounts for both the production of a sustained secondary circulation and its existence only during the flood phase of the tide. and finally, we attempt to define the stable parameter ranges for both types of convergence.

Estuaries are intrinsically complex and dynamic ecosystems that display marked spatial and temporal variability. Because estuaries are situated at the receiving end of catchment activities, they are at particular risk of alterations to their natural complexity. The overarching objective of this study was to gain an overview of the abiotic conditions and biotic response of the Goukamma Estuary, a small temporarily open/closed estuary (TOCE) which is situated in a relatively undisturbed catchment in the Southern Cape. Physico-chemical properties drive estuarine ecology, and together with biological indicators, are commonly assessed to determine the present status of an estuary. During the study, physico-chemical parameters reflected great spatial and temporal variability in response to the mouth state over a 13 month period. Parameters ranged within expected limits, as proposed by the conceptual model for water quality of TOCE’s (Snow and Taljaard 2007). Of particular importance was the prominent occurrence of salinity stratification and hypoxic conditions (dissolved oxygen [DO] < 3 mg l-1) during both open and closed mouth states. Data indicated that in the wide and shallow lower reaches, weak stratification gradients were present and oxygenated conditions (DO > 6 mg l-1) were maintained throughout the water column mainly by wind and tidal action. However, stratification increased towards the deeper, channel-like middle and upper reaches of the estuary, followed by a significant reduction in bottom DO concentrations and development of hypoxia and anoxia. Bottom water hypoxia commonly occurs in microtidal estuaries due to the limited influence of mixing forces, mainly by wind and tidal action. The Goukamma Estuary is a channel-like microtidal estuary where stratification effectively limited oxygenation of the bottom water which resulted in frequent occurrence of bottom water hypoxia. During June 2010 when the highest local rainfall (75 mm) was recorded for the region, salinity and DO data showed that this amount of rainfall was insignificant as it did not replenish the water column of oxygen. Only the surface 0.5 m layer was fresh and oxygenated while below this, the water column was completely hypoxic. In an unimpacted state, the Goukamma Estuary is a blackwater system and is expected to be nutrient poor; however, farming activities in the catchment have resulted in elevated nutrient concentrations. This study showed that significantly higher nutrient concentrations were measured in the middle and upper reaches of the estuary, adjacent to cattle farms situated in the floodplain of these reaches. Nutrient concentrations represented mesotrophic (dissolved inorganic nitrogen [DIN] > 500 μg l-1) to eutrophic conditions (dissolved inorganic phosphorus [DIP] > 25 μg l-1). Nutrient input stimulated phytoplankton to attain a significantly high biomass, ranging between 0.3 – 112 μg l-1 (~ 7.7 ± 1.3 μg l-1; n = 128) and 0.8 – 289 μg l-1 (~ 21.1 ± 4.4 μg l-1; n = 80) during the open and closed states, respectively. High organic loads are associated with high oxygen demands which consequently result in hypoxia following decomposition. Exacerbated by natural salinity stratification which effectively limits oxygenation of the water column, unnaturally high nutrient concentrations and coinciding organic loads place the estuary at particular risk of degradation. This study captured key patterns and processes by quantifying salinity, oxygen and nutrient concentrations in addition to biological indicators (phytoplankton biomass and community composition). Considering possible budget constraints, it is recommended that monthly salinity and oxygen concentrations should be monitored as well as seasonal nutrient concentrations. It is also recommended that riparian buffer zones should be established in the middle and upper reaches of the estuary, as these vegetation buffers have been well documented to contribute to nutrient attenuation and improved water quality from agricultural run-off.

The Fraser estuarine area is characterized by an abundance of biophysical resources interacting with high levels of human demand for food, recreation, transportation, industrial location, and other uses. Our society frequently relies on the market to allocate resources in a socially optimal fashion. But for estuarine resources this approach is often inadequate because externalities from resource uses are not considered, or because a competitive market is not operative. In such cases government intervention is considered necessary to allocate resources in accordance with societal preferences. This thesis seeks to evaluate the effectiveness of government intervention in allocating estuarine resources in the Fraser estuarine area for navigation and port development in a socially optimal fashion, through an examination of the planning process leading to the generation of a proposal to train the lower reaches of the main are of the Fraser River. The purpose of the proposal is to create, through a self-scouring channel, an improved draft for deep sea shipping. This proposal has been chosen for analysis because it represents a major demand on the resources of the estuary, and has considerable potential for affecting a wide range of interests. As such it should prove a good test of the effectiveness of government intervention in allocating estuarine resources in a socially optimal manner. This thesis thus has the following objectives: 1. To evaluate the effectiveness of the "ports provision system" in arriving at a socially optimal allocation of estuarine resources for navigation and port development. To achieve this objective it is necessary to achieve the following sub-objectives: 2. To identify those interests who will benefit and those who will bear a significant share of the costs that will result if the training works proposal is implemented. 3. To describe the activities and interactions among affected interests in the process of deriving the training works proposal. 4. To determine whether adequate information for the evaluation of alternatives has been generated. These objectives were pursued as follows. Normative criteria were derived for evaluating the effectiveness of an ideal process for allocating estuarine resources for navigation and port development. A basic assumption behind these criteria was that societal preferences can be elicited through a process of bargaining amongst legitimate interests. The interests affected by the training works proposal were identified by reviewing the potential effects on biophysical processes, by identifying other uses displaced by the project, and by a description of anticipated economic effects. The available literature on these factors was reviewed, and interviews were held with representatives of likely affected interests. Next, the involvement of interests in the planning process was determined. This historical antecedents to the training works proposal were outlined to place the project in context and to define the extent of past involvement by interest in port development. Those interests with a formal legislative basis for involvement in the process were then identified. The involvement of other interests was determined by reviewing written material and by informal discussions with as many affected interests as could be contacted within time constraints. For convenience, the planning process was considered in three stages: conceptualization of the problem, derivation of alternatives, and evaluation of alternatives. The decision stage, yet to come, was not considered. The effectiveness of the process in arriving at a socially optimal proposal was analyzed in terms of the extent to which affected interests were able to bargain "for the consideration of alternatives which they favoured, and the extent to which evaluative information generated on alternatives identified the effects on the various legitimate interests. Six general categories of information were evaluated. Finally, a number of behavioural factors which appear to have inhibited the generation of alternatives and of evaluative information were noted, based on a review of the literature on limits to rationality, and on interviews with actors involved in the planning process. The analysis showed that the planning process failed to meet the normative criteria and that the problem was of sufficient magnitude to seriously affect the optimal allocation of estuarine resources for navigation and port development. The ports problem was conceptualized in a manner that precluded the consideration of a wide range of alternative solutions, because only the values of those interests who would benefit from the proposal were brought to bear on the problem. Similarly, the alternative generated, and the evaluative information did not meet the concerns of many affected interests because they were excluded from the bargaining process. The attitudes of those interests involved were thus permitted to guide the process. There was little bargaining amongst interests to determine social preferences because many interests were excluded from the process or lacked the necessary evaluative information to become involved. Finally, elected representatives played a limited role in the process, permitting civil servants in powerful agencies to interpret societal preferences. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Unknown

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 77-80). Description: xii, 80 leaves : ill. ; 29 cm. / The lower distributional limits (fronts) of callianassid shrimp populations were observed at five sites in South Slough, Coos Bay estuary, Oregon. Fronts at four sites exhibited similar shoreward-seaward movements while the remaining site showed drastic population reductions. Shrimp density and body size were found to be significantly greater above than below the front. There was no consistent pattern found in grain size or interstitial water content across the front. In a controlled predator-exclusion experiment, resulting shrimp densities were not significantly different among treatments. Front shifts showed no pattern in response to treatments. These results imply that fish predation is not responsible for front placement. Trawls taken on both sides of the front produced similar densities of a predatory fish, Leptocottus armatus. Because predation pressure was calculated to be roughly equal above and below the front, Leptocottus is not expected to be responsible for position and movements of these fronts.

No description available.