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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Mytilus californianus community : studies on the composition, structure, organization, and dynamics of a mussel bed /

Suchanek, Thomas H. January 1979 (has links)
Thesis--University of Washington. / Vita. Bibliography: leaves [205]-227.
2

Effects of eutrophication on soft shore benthic community /

Cheung, Ka Chung. January 2005 (has links) (PDF)
Thesis (M.Phil.)--City University of Hong Kong, 2005. / "Submitted to Department of Biology and Chemistry in partial fulfillment of the requirements for the degree of Master of Philosophy" Includes bibliographical references (leaves 153-181)
3

Ecological status and conservation value of soft shore habitats in Hong Kong /

Tai, Koon Keung. January 2005 (has links) (PDF)
Thesis (M.Phil.)--City University of Hong Kong, 2005. / "Submitted to Department of Biology and Chemistry in partial fulfillment of the requirements for the degree of Master of Philosophy" Includes bibliographical references (leaves 143-161)
4

Interactions of seasonally changing physical factors and grazing affecting intertidal communities on a rocky shore

Cubit, John David, 1944- 03 1900 (has links)
Thesis (Ph.D.)--Oregon, Dept. of Biology Vita Bibliography: l. 118-122
5

Sandy beach morphodynamics and macrobenthic communities in temperate, subtropical and tropical regions : a macroecological approach

Soares, Alexandre Goulart January 2003 (has links)
A comprehensive study involving 52 microtidal beaches spanning from reflective to dissipative states and located in tropical, subtropical and temperate regions in the Atlantic, Pacific and Indian oceans was carried out to unravel the relative roles of latitude and beach morphodynamics in determining beach macrobenthic species richness, abundance, biomass and mean individual body sizes. Since beach slope is one of the most important factors controlling beach fauna, a model based on beach geometry was applied to the sub-aerial beach deposit to understand the role of physical factors in predicting equilibrium beach slopes. Additionally, it was tested if the occurrence of beach types is related to latitude, and how physical factors change with morphodynamics and latitude. The beach morphometric model makes three assumptions: 1) that the cross-section of a beach deposit is equivalent to a right-angled triangle, 2) that the physical hydrodynamic factors (wave height and spring tide amplitude) and the beach deposit characteristics (sand grain size, beach slope and width) are interchangeable with their geometric counterparts producing an equation to explain beach geometry, and 3) that the predicted beach slope is in equilibrium with the hydrodynamic and sedimentological forces. The equation for predicting beach slope was derived and then tested against field data collected over 52 beaches. The predicted slopes were not significantly different from the observed slopes of the studied natural beaches. However some estimated slopes were different than observed ones. Possible sources of deviation between calculated and observed slopes may be the systematic sampling errors associated with field data. Alternatively, observed slopes could be the result of past hydrodynamic conditions, explaining the differences with the slopes calculated by the beach morphometric model, which assumes a state of equilibrium between beach slope and hydrodynamic conditions. A higher correlation of beach faunal structure with observed slopes rather than with present hydrodynamic conditions could then be indicative of faunal responses to previous hydrodynamic conditions in the same way was the observed slopes. The beach morphometric model could therefore be also useful in predicting faunal responses to changing hydrodynamic conditions. Since the model does not consider wave period, it is concluded that further tests should be done using laboratory and time-series field data and incorporating the role of wave period and beach permeability to ascertain its predictive value. Tropical regions had significantly more beaches in a reflective state than temperate and subtropical regions. Some tropical beaches were fronted by coral reefs, which not only provided coarse carbonate particles, but also additionally dissipated the low wave energy present in these climatic areas. Only one dissipative beach with high energy was found in the tropics, in southeast Madagascar. Temperate and subtropical regions, on the other hand, were dominated by dissipative beaches with medium to fine sands. Open oceanic reflective beaches were non-existent in the subtropics and rare in temperate regions, only occurring in estuaries, enclosed bays or on islands facing the continent. Intermediate beaches were more common in the subtropics but also occurred frequently in the other two regions, having higher energy in temperate regions. Reflective beaches had significantly steeper slopes, coarser sands, smaller waves and shorter swash lengths when compared to dissipative beaches. Additionally, reflective beaches were narrower, had deeper water tables and in consequence shorter saturation zones. Wave periods and surfzone widths were on average larger on dissipative than on reflective beaches. The frequency of occurrence of beach types is therefore related to the climatic signature of each latitude. Mid latitudes would be predicted to have more dissipative beaches with large and long waves because of their proximity to the storm generating belt around 50-60° S - these beaches will have a predominantly finer sands because of the input by rivers in rainy areas. Lower latitudes will have more reflective beaches due to a modal low energy wave climate and also because of the presence of inshore and offshore biotic structures such as coral reefs that dissipate even more the energy from the waves. Tropical and subtropical regions had larger marine species pools than temperate regions. After controlling for biogeographical differences in total species pool, dissipative beaches were on average significantly richer than intermediate and reflective beaches. Crustaceans were also more diverse on dissipative beaches, this difference being not significant for either molluscs or polychaetes. Significant relationships were found between total beach species richness (with or without terrestrial species), crustacean and mollusc species richness with beach morphodynamics as represented by the Dean’s index. Indices incorporating the role of tide, such as BSI, were less important in predicting species richness on the microtidal beaches studied here. Several other physical factors were also significantly correlated with species richness, the most important being the Beach Deposit Index, i.e. BDI, a composite index of beach slope and grain size. The highest correlation was between BDI and relative species richness, i.e. local beach species richness / regional species richness. Total regional marine species richness was higher in Madagascar and North Brazil (tropical beaches) than in Southeast Brazil (subtropical), or the West Coast of South Africa and South-Central Chile (temperate beaches). Not only was the pool of species capable of colonizing beaches richer in tropical and subtropical regions, but also local diversity of each morphodynamic beach type was higher among tropical beaches than their temperate counterparts. Although the results of this study agree with the predictions of the swash exclusion hypotheses, several reflective and intermediate beaches had higher species richness than predicted before and this seems to be linked to the presence of finer sediments and a less turbulent flow for larvae to settle. It is concluded that beach species richness is not necessarily controlled by one major morphodynamic parameter; this control is complex and probably involves multiple interacting biotic (biological interactions) and abiotic (e.g. grain size, wave height, beach slope and width, water table) factors. Species richness seems to be controlled on two different scales: on an evolutionary one where tropical and subtropical regions have higher regional and local diversity due to higher speciation rates; and on an ecological scale, where fine grained sand beaches have their carrying capacity enhanced by higher larval settlement rates and survival of recruits towards adulthood. On average dissipative beaches had higher total densities and macrofaunal abundances than reflective ones. Crustaceans, terrestrial species and cirolanid isopods such as Excirolana spp. were also more abundant on dissipative beaches. The difference was not significant for molluscs and polychaetes. Significant relationships were found between total abundance, crustacean species richness and beach morphodynamics as represented by the Dean’s index. Again, BSI was less important than individual physical factors in determining faunal abundance on the studied microtidal beaches. Several other physical factors were also significantly correlated with abundance, the most important being the Beach Deposit Index (BDI). The highest correlation was between BDI and total macrofaunal abundance. Factors related to surf zone processes, and possibly productivity, were highly correlated with total community, crustaceans, Excirolana spp. and terrestrial species abundances. The abundances of polychaetes and molluscs were better correlated with factors related to the beach deposit (BDI, slope, grain size and water table depth). Significant differences were observed between latitudinal regions for the average beach and also for each beach type. In general temperate beaches harboured larger community densities and abundances, and also crustacean, Excirolana spp. and terrestrial abundances. Mollusc and polychaete abundances were larger on subtropical and tropical beaches. The control of abundance on a sandy beach is complex and involves multifactorial processes at evolutionary and ecological scales. At evolutionary scales animals seem to attain higher abundances in the region where they first evolved, e.g. amphipods and isopods in temperate regions. At ecological scales they attain higher abundances where productivity is higher (total macrofaunal, crustaceans, Excirolana spp., terrestrial spp.) or where the settlement environment is more benign (molluscs and polychaetes). Dissipative beaches supported larger average and total community biomass than reflective beaches. Crustaceans, terrestrial species and cirolanid isopods such as Excirolana spp. also had larger biomass on dissipative beaches. The difference was not significant for molluscs and polychaetes. Significant relationships were found between the biomass of community and taxonomic groups with beach morphodynamics as represented by the Dean’s morphodynamic index. On the microtidal beaches studied here, BSI was less important than other morphodynamic indices and single physical factors in determining faunal biomass and mean individual body size. Surf zone characteristics such as wave height, period and surf zone width had the highest correlations with community, crustacean.
6

Investigating the ecological implications of wrack removal on South Australian sandy beaches

Duong, Huynh Lien Stephanie, Unknown Date (has links)
Thesis (Ph.D.)--Flinders University, School of Biological Sciences. / Typescript bound. Includes bibliographical references: (leaves 329-341)
7

Human recreational activity and its impact on a metropolitan coastline

Van Herwerden, L January 1989 (has links)
Includes bibliography. / Recreation has an important social function in modern societies, with ever-increasing pressures in the day-to-day life being felt by most people. This study addresses the impact of recreational activity on metropolitan shorelines, with particular reference to the False Bay shoreline. During summer holiday periods shoreline utilization in the Western Cape peaks on the public holidays of 26 December, 1 and 2 January, beach attendances reaching levels of 2 to 10 times higher than attendances on other days during the summer holidays. The greatest proportion of visitors to the beach (94%) engage in non-exploitative activities, such as sunbathing and swimming. Most visitors occur on the beaches between 12h00 and 16h00, week-ends being most popular during out-of-season periods, but in-season week day attendances exceed those of weekends. Only 6% of visitors surveyed were engaged in exploitative activities such as angling and bait- or food-gathering. Conservation awareness of visitors to the shore is related to the place of residence of the person, as well as activity engaged in by the person. Fish numbers and their size frequency distributions in protected areas differs to those of unprotected areas. If boulders on a sheltered shore are over-turned during bait gathering it has an adverse effect on the boulder communities, whether the boulders are replaced or left over-turned. When bait gatherers target on mussel-worms as bait, they may cause inadvertent damage to the primary matrix of mussel bed or tube-worm reef in the process, thereby affecting ecological succession processes in the intertidal environment. Management of metropolitan shorelines must therefore provide for quality recreational experiences, while applying conservation measures to selected areas that are susceptible to over-exploitation under the onslaught of ever-increasing numbers of recreationists. For such measures to be of any benefit to the marine environment, it is essential that people are not only informed, but that the regulations are also properly enforced.
8

The ecology and biology of marine cladocerans in Tolo Harbour, Hong Kong. / CUHK electronic theses & dissertations collection

January 2001 (has links)
Ji Changhai. / "February 2001." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 156-183). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese. / Abstracts in English and Chinese.
9

The distribution of intertidal macrofauna in Tolo Harbour, Hong Kong, with respect to selected environmental parameters.

January 1976 (has links)
Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 141-154.
10

Dynamics of a coastal upwelling and the Pearl River plume in Guangdong coastal waters. / CUHK electronic theses & dissertations collection

January 2013 (has links)
沿岸上升流和河流沖淡水都會嚴重影響近岸水體的物理、化學性質及其生態系統;南海北部的廣東沿岸同時存在著這兩種現象,因此對於沿岸上升流和沖淡水的運動規律和動力機制的研究對於認識廣東沿岸水體性質和生態環境的變化具有重要的理論意義。本文首先利用多種衛星遙感觀測資料和實地調查資料研究珠江沖淡水和紅海灣內的上升流進而揭示其空間分佈特徵和時間變化規律。而後利用三維的高解析度區域海洋模式(ROMS)建立一個適用於南海北部的海洋動力模式,從而成功反演珠江沖淡水和紅海灣內上升流的發展變化規律,進而揭示對其產生影響的動力原因。 / 通過分析MODIS在2003年7月14日至16日的海表面溫度影像以及同一時期的QuikSCAT風場資料,本文發現在西南風盛行時紅海灣記憶體在一個明顯的上升流區域,而且湧升的冷水首先在紅海灣的西岸出現並呈尖形向東南輸送。通過MODIS衛星觀測的海表面28oC等溫度線和模式類比結果的相互印證,證明本文利用ROMS建立的上升流模式能夠成功再現上升流的發展變化過程。基於模式類比結果的動量平衡分析揭示沿岸方向的壓強梯度和非線性項導致湧升的冷水首先出現在紅海灣西岸,而冷水的楔形離岸輸運則是由東南風引起的Ekman輸運和水準的非線性共同作用的結果。本文還進一步討論了季風、潮汐和海底地形對上升流的產生和擴散過程的影響。模式類比結果表明:在紅海灣觀測到的海表冷水是由西南風驅動的上升流造成的;由海底地形引起的內潮和上升流之間的相互作用會增強底層水的上升運動;湧升冷水的離岸輸運距離受海底地形在垂直於岸線方向的影響:坡度較緩的海底有助於冷水在距離海岸較寬的區域湧升至水面,而坡度陡的海底會將上升流限制在距離海岸較近的區域。 / 珠江沖淡水是本文的另外一個研究重點。通過對2012年6月4日-14日在珠江口和鄰近海域的調查資料的分析,可以看出調查期間珠江沖淡水呈現兩種截然不同的分佈特徵。利用ROMS的嵌套技術,本文建立了一個覆蓋南海北部陸架區的小區域模式。通過與實測資料的對比,驗證了本文建立的區域模式可以很好的反演珠江沖淡水在不同風場作用下的空間分佈特徵。基於模式類比結果的動量平衡分析表明,除了由風引起的海表面Ekman輸運外,非線性对流项項是另外一個影響沖淡水離岸輸運距離的重要因素。 / 通過計算不同風場作用下不同潮時的Froude數發現,在東南風和大潮共同作用下,珠江口鋒面處於超臨界狀態。這與實際調查結果相符合。進一步對潮汐羽流的分析表明,在東南風盛行時,珠江沖淡水由潮汐羽流、再迴圈羽流和羽流沿岸流三部分組成。當盛行風向轉為西南風時,再迴圈羽流部分消失。此時,珠江沖淡水羽流只由潮汐羽流、羽流遠場兩部分組成。計算海表面水準方向上的鹽量輸運發現,鹽量輸運受風場和潮汐的共同作用影響,潮汐導致的表層負鹽度通量可達到風生平均流引起表層負鹽度通量的12.5%。風場影響著沖淡水區域的垂向層化強度和離岸輸運距離。東南風和大潮的共同作用下,水體垂向混合加強,沖淡水離岸輸運距離變短。而盛行西南風時,強密度躍層將表層風引起的混合與底層混合隔開,有助於層化的建立,此時表層沖淡水離岸輸運距離增加。 / The upwelling event that occurred in Guangdong coastal water during 14-16 July, 2003 is observed by using satellite multi-sensor data including the Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature (SST) and QuikSCAT ocean surface winds. Successive MODIS SST images reveal a jet-like upwelling cold water body in surface layer under the forcing of southwesterly winds. The ROMS is used to simulate the upwelling process and explore its dynamics. The model successfully reproduces the jet-like shape of the surface upwelling water as well as the upwelling-developing process by comparisons of 28°C isotherms between the modeling and MODIS SSTs. Analyses of modeled momentums reveal that the large offshore transport appeared on the west side of Honghai Bay as results of high alongshore pressure gradient and nonlinear advections, and in addition to the offshore-ward Ekman transport generated by the southwesterly winds, the enhanced horizontal advection also played an important role in developing the prominent upwelling in Honghai Bay. / As testified by a numerical experiment, it is the wind-driven upwelling not the wind-induced vertical turbulent mixing that induced the surface cold water. Further numerical analyses reveal strong internal tides occurring in Honghai Bay caused by the local bottom topography. The interaction between the upwelling and internal tides enhances the bottom water uplifting. The offshore expansion of the upwelling water is controlled by the cross-shore topography slope: a gentle and offshore-extended slope helps the bottom water to climb up to the surface in a wide range in cross-shore direction, whereas a steep and narrow slope restricts the expansion of the upwelling water and confines the cold water in a narrow band along the shore. / A sea cruise was carried out to capture Pearl River plume structure in the Pearl River Estuary (PRE) and its adjacent coastal waters from 4 June to 14 June, 2012. The cruise data are analyzed to unveil the plume dynamics. A nested model is used to simulate the plume expansion process as well. Model results are compared with cruise observations and tidal gauge sea level data. Modeling results suggest that there is a sub-tidal, anti-cyclonic bulge on the west side out of the river mouth under southeasterly winds, which constitutes a plume re-circulating. When the wind changes to the southwesterly, however, the plume re-circulating vanishes and a plume far-field appears. / The distinct, supercritical plume front occurs with southeasterly winds prevailing in spring tide. The tidal salt deficit flux can reach as high as 12.5% of the mean current flux, and indicates an interaction between the wind forcing and tides. The variation of plume stratification is studied by a scalar parameter. It is found that the stratification of the plume is sensitive to the wind forcing: The southeasterly winds can enhance vertical mixing in the whole water column and restrict seaward expansion of the plume water. Under the southwesterly winds, the strong stratification acts as a barrier separating wind-induced surface vertical mixing and bottom mixing. The plume water in the surface layer maintains its stratification and spreads horizontally. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Gu, Yanzhen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 137-148). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / ABSTRACT --- p.I / 摘要 --- p.IV / CONTENTS --- p.VI / List of Tables --- p.VIII / List of Figures --- p.VIII / Acknowledgments --- p.XII / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- General Circulation in the Northern SCS --- p.6 / Chapter 1.1.1 --- Dongsha Current --- p.6 / Chapter 1.1.2 --- SCS Warm Current --- p.7 / Chapter 1.1.3 --- Other Features --- p.8 / Chapter 1.2 --- Coastal Upwelling --- p.8 / Chapter 1.2.1 --- Wind-induced Coastal Upwelling --- p.8 / Chapter 1.2.2 --- Overview of Coastal Upwelling Studies --- p.9 / Chapter 1.3 --- The Pearl River Plume --- p.12 / Chapter 1.3.1 --- Physical Setting --- p.12 / Chapter 1.3.2 --- Overview of River Plume Studies --- p.15 / Chapter 2 --- Regional Ocean Model System --- p.18 / Chapter 2.1 --- Equation of Motion --- p.19 / Chapter 2.2 --- Model Time-Stepping Scheme --- p.20 / Chapter 2.3 --- Boundary Conditions --- p.21 / Chapter 2.4 --- Coordinate System Transformation --- p.22 / Chapter 2.5 --- Vertical Viscosity and Diffusion --- p.26 / Chapter 3 --- Dynamical Study of Coastal Upwelling --- p.27 / Chapter 3.1 --- Satellite Data --- p.27 / Chapter 3.2 --- Data Interpretation --- p.28 / Chapter 3.2.1 --- Upwelling and Wind Fields --- p.28 / Chapter 3.2.2 --- Horizontal Structure and Expansion of the Cold Water Area --- p.33 / Chapter 3.3 --- Model Configuration --- p.34 / Chapter 3.4 --- Model Results --- p.38 / Chapter 3.4.1 --- Sea Surface Temperature and Horizontal Currents --- p.38 / Chapter 3.4.2 --- Cross-shelf Structure --- p.44 / Chapter 3.4.3 --- Momentum Balance --- p.46 / Chapter 3.5 --- Discussions --- p.50 / Chapter 3.5.1 --- Winds --- p.50 / Chapter 3.5.2 --- Internal Tides --- p.53 / Chapter 3.5.3 --- Topography --- p.56 / Chapter 4 --- Dynamical Study of the Pearl River Plume --- p.63 / Chapter 4.1 --- Cruise Observations --- p.63 / Chapter 4.2 --- Data Interpretation --- p.66 / Chapter 4.2.1 --- Observed Surface Salinity Distribution --- p.66 / Chapter 4.2.2 --- Salinity Vertical Distribution --- p.68 / Chapter 4.2.3 --- River Plume Front --- p.74 / Chapter 4.3 --- Model Configuration --- p.76 / Chapter 4.3.1 --- Northern South China Sea Model --- p.78 / Chapter 4.3.2 --- Pearl River Estuary Model --- p.79 / Chapter 4.4 --- Model Results and Verification --- p.80 / Chapter 4.4.1 --- Validation of Surface Salinity --- p.80 / Chapter 4.4.2 --- Validation of Salinity Profile --- p.82 / Chapter 4.4.3 --- Validation of Tidal Elevations --- p.83 / Chapter 4.4.4 --- Plume Horizontal Structure --- p.87 / Chapter 4.4.5 --- Plume Cross-shelf Structure --- p.91 / Chapter 4.4.6 --- Momentum Balance --- p.95 / Chapter 4.5 --- Stratification --- p.101 / Chapter 4.6 --- Plume frontal Froude number --- p.106 / Chapter 4.7 --- Tidal Plume --- p.111 / Chapter 4.8 --- Horizontal salt deficit flux --- p.114 / Chapter 4.9 --- Turbulence Mixing --- p.118 / Chapter 5 --- Conclusions --- p.124 / Chapter Appendix I: --- List of Publications during Ph. D. Study --- p.128 / Chapter Appendix II: --- MODIS SST Image --- p.129 / Reference --- p.137

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