Rozprawy doktorskie: „Estuaries”

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Young, Ruth Anne. "Biotic Responses to Urbanisation in Mangrove Dominated Estuaries". Thesis, Griffith University, 2009. http://hdl.handle.net/10072/367651.

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Increasing urbanisation of coastal areas is placing unprecedented pressure on estuarine environments. Impacts associated with urbanisation can alter the health of estuarine ecosystems, reducing their capacity to provide valuable ecosystem services. In order protect these environments, relationships between estuarine health and urbanisation should be understood and applied to sustainable urban planning in coastal areas. Responses measured in estuarine biota offer much potential for providing pragmatic and sensitive means for the detection of urban impacts in estuaries. I assessed the responses of estuarine biota to increasing levels of urbanisation in the rapidly developing coastal region of southeast Queensland, Australia. I measured a suite of biotic indicators, namely: the δ15N of mangroves and crabs as a tracer for urban N sources, sediment chlorophyll a concentration (Chl a) as an estimate of the biomass of microphytobenthos (MPB), and a condition index in crabs, measured as the hepatosomatic index (HI). Urbanisation was estimated as the percentage of catchment covered by impervious surfaces (impervious cover, IC). Increases in impervious surfaces such as roads, footpaths and car parks are closely linked to urbanisation. These surfaces concentrate and convey pollutants generated from urban activities into coastal waterways and estuaries, thus making IC a useful indicator of urban impact.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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2

Kaselowski, Tanja. "Physico-chemical and microalgal characteristics of the Goukamma Estuary". Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1011130.

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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.

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Reay, William Glendon. "Estuarine sediment nutrient exchange : the importance of physical transport mechanisms and benthic micro-communities /". Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07122007-103937/.

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Van, Niekerk Lara. "A framework for regional estuarine management : a South African case study". Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/1659.

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Chuwen, Benjamin Michael. "Characteristics of the ichthyofaunas of offshore waters in different types of estuary in Western Australia, including the biology of black bream Acanthopagrus butcheri /". Murdoch University Digital Theses Program, 2009. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20100210.154423.

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Veilleux, Lorraine. "Physical oceanography of northern estuaries". Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59830.

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Within the context of oceanographic research on northern estuaries in James Bay and Hudson Bay, and in relation with hydroelectric developments and their impact on the physical environment, two studies were undertaken. Both concern the importance of bottom topography, tidal motion and fresh water input on the estuarine processes in these areas.
The first one, in Rupert Bay (south-eastern corner of James Bay), describes tidal and local wind effects on circulation and mixing patterns for summer conditions. An estimate of terms in the lateral momentum equation shows that the centrifugal acceleration, the Coriolis force and the baroclinic pressure gradient are the most important forces at a mid-bay cross section transect.
The second study is concerned with the freshwater plume of Great Whale River (south-eastern Hudson Bay). CTD measurements were used to examine the lift-off point of the plume for under-ice and increasing discharge conditions. Comparison with existing models shows them to be inappropriate for under-ice conditions. Finally, the presence of supercooled water masses in the region of the study is reported.

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Burningham, Helene. "Morphodynamics of west Donegal estuaries". Thesis, University of Ulster, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274556.

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Barnes, Jonathan. "Nitrous oxide in UK estuaries". Thesis, University of Newcastle upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273682.

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Bosco-Santos, Alice 1987. "Concentrações de elementos químicos em fígado e músculo de peixes demersais do sistema estuarino de Santos-Cubatão (SP) = aspectos temporal e espacial". [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287681.

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Orientador: Wanilson Luiz Silva
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
Made available in DSpace on 2018-08-19T12:23:48Z (GMT). No. of bitstreams: 1 Bosco-Santos_Alice_M.pdf: 4095756 bytes, checksum: f3f332df09dceb48c16a8ff0764fe038 (MD5) Previous issue date: 2011
Resumo: A região de Cubatão (SP) abriga o maior polo industrial da América Latina e nos anos de 1980 ficou internacionalmente conhecida como um dos lugares mais seriamente poluídos do planeta por consequência de atividades industriais que ocasionaram grandes perturbações ambientais locais. Desde então, a contaminação da biota do sistema estuarino de Santos-Cubatão vem sendo monitorada e tem apresentado níveis elevados de elementos químicos nos organismos. Entretanto, ainda não foram realizados estudos que levem em consideração amostragens sazonais, que poderiam refletir as consequências das variações físico-químicas do ambiente na transferência de elementos químicos para a biota. No presente estudo, concentrações de As, Se e metais (Cd, Cr, Cu, Fe, Mn, Ni, Pb e Zn) foram determinadas em tecidos hepático e muscular de quatro espécies de peixes demersais do sistema estuarino em foco. No inverno/2010 e verão/2011, exemplares de Diapterus rhombeus, Genidens genidens, Centropomus parallelus e Mugil Liza foram coletados nos rios Morrão, Casqueiro e Cubatão. As amostras foram liofilizadas e os elementos químicos extraídos por digestão ácida com posterior análise por ICP-MS. Os resultados foram comparados ao LMT (limite máximo de tolerância) determinado pelo Ministério da Saúde do Brasil. Concentrações de As, Cr, Cu, Fe, Mn, Pb, Se e Zn foram, em geral, acima do LMT estabelecido pela legislação brasileira, e o tecido hepático apresentou concentrações químicas muito superiores às registradas no tecido muscular. Mugil Liza foi a espécie que acumulou mais elementos químicos em ambos os tecidos e é a melhor bioindicadora da área de estudo. As associações com o substrato e o hábito alimentar mostraram-se fatores decisivos na absorção de elementos químicos pelos organismos. Variabilidades sazonais foram observadas para as concentrações de Cd, Cr, Cu, Fe, Mn e Zn nos tecidos dos organismos analisados. Apesar de o rio Morrão ser considerado um dos cenários mais impactados do sistema estuarino de Santos-Cubatão, a biodisponibilidade de elementos químicos naquele ambiente não parece diferente de ambientes historicamente menos impactados, como os rios Casqueiro e Cubatão
Abstract: The city of Cubatão (SP) holds the largest industrial center in Latin America. During the 1980s, this region became internationally known as one of the most polluted cities in the world. This was a result of local industrial activities that caused large local environmental disturbances. Since then, biota contamination along the Santos-Cubatão estuarine system has been monitored, and high levels of contamination amongst organisms have been found. Environmental monitoring of the biota, taking into account the importance of seasonal variability, has not been considered. Concentrations of As, Se and metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined in liver and muscle tissue of four species of demersal fishes of the Santos-Cubatão estuarine system. Specimens of Diapterus rhombeus, Genidens genidens, Centropomus parallelus and Mugil Liza were collected in summer and winter, in the Morrão, Casqueiro and Cubatão rivers. The samples were freeze-dried, underwent acid digestion and subsequently were analyzed using an ICP-MS. The results were compared to the LMT (maximum allowable) guidelines determined by the Brazilian Ministry of Health. Concentrations of As, Cr, Cu, Fe, Mn, Pb, Se, and Zn were generally above the LMT, as established by Brazilian legislation. Specific organs were analyzed and compared, for instance, liver tissue had contaminant concentrations much higher than those recorded in the muscle tissue. Mugil Liza was the species that accumulated more chemical elements in both tissues. The association with the substrate and eating habits proved to be decisive factors in the absorption of specific contaminants by the organisms. Seasonal variability was observed for concentrations of Cd, Cr, Cu, Fe, Mn, and Zn in the tissues of organisms analyzed. Although the Morrão river is considered one of the scenarios most impacted of the Santos-Cubatão estuarine system, the bioavailability of specific chemical pollutants in this work does not support this scenario, as indicated by the results found in the less impacted environments, such as Cubatão and Casqueiro rivers
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências

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Lee, Deborah Ellen. "An application of the choice experiment method to estimate willingness-to-pay for and guide management on estuarine recreational services". Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1020239.

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Among the world‘s ecosystems, estuaries have the highest total economic value per hectare. They are dynamic coastal biomes that provide a host of different goods and services to the surrounding terrestrial and aquatic environments and the people who utilise them. These goods and services include, inter alia, nursery areas for marine organisms, harvested natural resources (such as fish, shell-fish, bait organisms, reeds and mangroves), flood attenuation, water purification, nutrient and sediment sinks, waste disposal, transport, aesthetic beauty and areas for swimming, boating and fishing. Assessing the condition of estuaries is difficult as their state can change depending on what is being measured. Assessments have been carried out on the health of estuaries in South Africa with the results of these studies being used as inputs to the process of assessing the minimum water supply requirements for each estuary (ecological reserve) in order to maintain or improve its functionality. These ecological reserve requirements are assigned using Resource Directed Measures (RDM). These measures, however, have been criticised for being highly complex and too costly to implement for all South African estuaries within a reasonable time period. Another concern is that the levels of demand for recreational goods and services provided by the estuary are not taken into account when assessing estuarine value. It is important to understand that the use of estuaries for recreational purposes is inextricably linked to their health and sound ecological functioning. Although South African estuaries have been quite well buffered from impacts until only very recently, their use and pressures have escalated faster than what conservation authorities and policy makers have been prepared for over the last couple of decades. There is thus mounting pressure on estuaries as recreational outlets, which, in turn, has led to their functional deterioration as well as deterioration in the quality of the recreational experience as a whole. One implication for management is that more and more trade-offs have to be made in an attempt to balance the conservation and recreational use of estuaries.

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Zhang, Jisheng. "Modelling of astronomical tide and storm surge in estuary". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=26090.

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Stenström, Petter. "Exchange flows in estuaries and archipelagos". Doctoral thesis, KTH, Land and Water Resources Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3546.

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Different aspects of the exchange of water and tracersbetween adjacent coastal basins, and between the coast and thesea, are addressed. Deviations from the inviscid hydraulicprediction of flow rates and interface heights in maximaltwo-layer exchange flows due to viscous effects are quantifiedby means of non-hydrostatic, three-dimensional numericalmodeling. Simulations are made for different strait geometriesand with a time-dependent barotropic flow to determine when andwhere vertical mixing and the resulting recirculation oftracers preferentially take place (Paper I). Non-hydrostaticthree-dimensional numerical modeling is also performed to studythe variability in circulation and stratification in a tidallyinfluenced estuary. In particular, two processes that act todecrease the rate of flushing of tracers are addressedturbulent mixing and secondary circulation, i.e. circulationperpendicular to the longitudinal estuary axis (Paper II).Schemes for modeling water exchange in an archipelago, i.e. ina complex system of basins and interconnecting straits, arediscussed (Paper III). Problems relating to Bernoulliaspiration of dense water from below the sill crest,multi-layer stratification, and to some extent rotationalcontrol in parallel straits are addressed.

Methodological aspects of both three dimensional numericalmodeling and of solution of the inviscid two-layer straitexchange problem are discussed. In the three-dimensionalnumerical modeling two issues are central: (i) theimplementation of open boundary conditions that allow a meanflow to be forced from one of the boundaries, while at the sametime let barotropic and baroclinic waves be radiated out of thedomain with minimum reflection, and (ii) the implementation ofa subgrid closure scheme to calculate the vertical eddyviscosity and diffusivity coefficients locally fromresolved-scale shear and stratification.

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Lemley, Daniel Alan. "Assessing symptoms of eutrophication in estuaries". Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/3427.

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Water quality and ecological integrity of estuaries reflect activities within the entire upstream catchment. Much emphasis has been placed on the response of estuaries to anthropogenic stressors through the use of monitoring programmes. Key to the success of these programmes is the use of indicators as they transform data into useful information. The ultimate aim of this study was to identify eutrophic symptoms in selected estuaries in the Gouritz Water Management Area (WMA) using a multi-metric classification method. The study sites included the permanently open Duiwenhoks, Goukou, Gouritz, and Kaaimans estuaries, as well as the temporarily open/closed Hartenbos, Klein Brak, Great Brak, Gwaing, and Goukamma estuaries. Initially, the “pressure” associated with all the estuaries in the Gouritz WMA was determined (e.g. total daily nutrient loads and changes in river inflow affecting flushing time) using long-term flow and water quality monitoring data provided by the Department of Water Affairs (DWA). Subsequently, the “state” of the selected estuaries was assessed using a variety of indicators, including: inorganic nutrients (~ N and P), phytoplankton, epiphytes and microphytobenthos. Estuaries with longer flushing time suggested greater vulnerability to eutrophication. For example, the Gwaing (281.11 kg DIN d-1; 78.85 kg DIP d-1) and Hartenbos (38.33 kg DIN d-1; 21.51 kg DIP d-1) estuaries generally received the highest daily inorganic nutrient loads. However, at the time of sampling, the Hartenbos Estuary had a longer flushing time (i.e. weeks) compared to the Gwaing Estuary (i.e. couple of days). Field data confirmed the greater vulnerability to eutrophication associated with longer flushing times, as the indicators measured in the Hartenbos Estuary exceeded all the proposed ‘thresholds’ of a eutrophic system (~ overall ‘Poor’ condition). The Great Brak Estuary (~ overall ‘Fair’ condition) provided an interesting example where eutrophic symptoms were only detected when assessing the microalgal primary producers (i.e. high biomass and low diversity). Furthermore, the need to distinguish between naturally and anthropogenically induced symptoms was highlighted. One such scenario was noted in the Kaaimans Estuary, where its natural hydro-morphological characteristics (i.e. steep banks, low river inflow, and deep/narrow channel) led to the possible exaggeration of its overall eutrophic condition, i.e. received a ‘Fair’ rather than ‘Good’ rating, arising from ‘Poor’ ratings for dissolved oxygen and benthic diatom diversity. Overall, this study demonstrated the importance of adopting a holistic approach when assessing the condition and trophic status of estuaries. Studies such as these allow for the detection of vulnerable and degraded systems, which can provide important information with regards to the identification of management priorities.

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Weltmer, Micah A. "Stratified fronts in well-mixed estuaries". Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/37742.

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Approved for public release; distribution is unlimited
The occurrence of tidal intrusion fronts in a well-mixed estuary is demonstrated through both model simulation and field observation. Strong vertical mixing in well-mixed estuaries typically does not allow for development of stratification, which is a defining feature of tidal intrusion fronts. New methodology to compute a mutual realization surface of critical width and depth from model output is described that evaluates how the geometry of a basin releases tidal inflow from the hydraulic control of an inlet and the resulting front character. Force balance relationships of these features are evaluated in three dimensions for the first time. From this, Froude angle techniques are adapted to assess and predict how the geometry controls the behavior of the front after it is formed. Intrusion fronts observed in the field do not precisely conform to the conceptual model, but a modest field validation of Froude angle usage informs an axis rotation that results in agreement with established hydraulic theory. Frontogenetic mechanisms are proposed from the observations to describe the importance of morphological complexity and water mass segregation to the occurrence of bathymetrically induced confluent subduction in a well-mixed estuary.

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Quinnell, Susan Elizabeth. "Estuarine Canaries: Macrobenthos Measures Pollution when Chemical Tests Cannot". Thesis, Griffith University, 2012. http://hdl.handle.net/10072/366573.

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Bramble Bay, an estuary with a long history of contamination, appears to have crossed multiple tipping points into a state of unstable biomass dominated by opportunistic species. In early 1996 mass mortality events began to affect the bay’s macrobenthic community within a few days of modest rainfall (30 mm) over the catchments. The numbers of wading birds and fish using the beach at such times greatly declined. Between mortality events the macrobenthos staged partial recoveries. However, 10 years later the beach had not attained the diversity of species it supported prior to 1996. Also, the riverine estuaries that drain the catchments had been severely affected. Monitoring in 1998 – 2000 showed that the abundance of riverine macrobenthos in six drainage systems was < 15% of that in 1972 – 1973 when these drainage systems were extensively surveyed and < 2.5% of that after extreme flooding in 1974. Remarkably, the variance of total abundance within estuaries had been reduced by 90 - 99%. Nearly all of the once-dominant peracarids had gone. Chemical tests could not explain this. Nor are other simplistic explanations credible, such as floods or changes in the rate of sedimentation, because only some components of the macrobenthos have been adversely affected. Most deposit feeders have been severely reduced, however, deposit-feeding annelids as well as suspension feeding molluscs and crustaceans have continued to thrive amongst the sediments.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Donald, Ian R. "A preliminary assessment of the hydrodynamics of the Touw River and Wilderness Lakes system with emphasis on the management of the estuary mouth". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85775.

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Thesis (MEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The Touw River estuary and Wilderness coastal lakes is a sensitive system from a flooding and ecological viewpoint and, therefore, careful consideration is placed on the hydrodynamics and salinity levels within the system. The estuary consists of a “temporary open/closed” estuary, where during closed mouth conditions, the sand bar at the estuary mouth is artificially managed in an attempt to reduce flood water levels in the system. The reason behind this management strategy is the construction of residential property along the flood plains of the estuary and coastal lakes, which in the past, had been exposed to regular cycles of inundation during flood events. In an attempt to reduce flood water levels in all water bodies and hence reduce the risk of inundation, a management policy was formulated. The past and present management plan is to maintain the sand bar at Touw estuary mouth, during closed mouth conditions, at an elevation of between +2.1m to +2.4m MSL, based on proposals made by the CSIR in 1981. Recent flood events, after the implementation of the management policy, still occasionally result in significant inundation of residential property, which has raised concern for some interested parties over the effectiveness of the management strategy. Furthermore, a growing concern was also evident over the long term wellbeing of the system from an ecological viewpoint. Historical data shows significant changes in salinity levels since the implementation of the management strategy which could impose negative long term effects on the system. In this study, numerical models were consequently constructed and applied in order to analyse the effectiveness of the current management policy and recalculate flood water levels under a number of proposed scenarios. Long term salinity changes were also analysed in an attempt to better understand salinity propagation throughout the system, using extreme hypothetical cases. Through the analysis of the simulation results, it was concluded that flood water levels in the Touw estuary were almost completely dependent on the size of the Touw River flood and the initial height of the sand bar at the estuary mouth. Whereas, water levels in the coastal lakes are almost entirely dependent on the quantity of runoff into the lakes and their initial water levels. The current management plan, involving only artificial manipulation of the sand bar at the estuary mouth, therefore has a fairly insignificant effect on flood water levels achieved in the coastal lakes. Furthermore, it was concluded that the construction of the preparatory channel is a vitally important aspect of the current management plan and that skimming of the sand bar alone is ineffective to completely mitigate the risk of residential inundation along the banks of the Touw River. The salinity modelling study provided a first indication of the salinity characteristics within the system. It was found that the penetration of seawater into the system was less prominent as the water bodies became further removed from the ocean and that a direct relationship was evident between the volume of direct freshwater inflow to a water body and the degree of salinity variation in that specific water body. In water bodies with high volumes of direct freshwater inflow such as the Touw estuary, a large degree of salinity variation is evident. However, in water bodies with no freshwater inflow, such as Rondevlei, salinity levels remain more stable and are less likely to fluctuate.
AFRIKAANSE OPSOMMING: Uit ‘n vloed- en ekologiese oogpunt is die Touwsriviermonding en Wilderniskusmere ‘n uiters sensitiewe stelsel en daar is dus deeglike oorweging gegee aan die hidrodinamika en soutvlakke in die stelsel. Die monding bestaan uit 'n "tydelike oop / geslote" monding, en tydens geslote mondtoestande word die sandbank by die riviermond kunsmatig beheer in 'n poging om vloedwatervlakke binne die stelsel te verminder. Die rede vir hierdie strategie is omdat baie residensiële eiendomme langs die vloedvlaktes van die monding en kusmere gebou is, wat in die verlede aan 'n gereelde siklus van oorstromings blootgestel is tydens vloede. In 'n poging om vloedwatervlakke in al die watermassas te verminder, en sodoende die risiko van oorstroming te verminder, is 'n bestuursbeleid geformuleer. In beide die vorige en die huidige bestuursplanne is die sandbank in die Touwsriviermond tydens geslote mondtoestande in stand gehou op 'n hoogte van tussen 2,1 m en 2,4 m MSL, gebaseer op die voorstelle wat deur die WNNR in 1981 gemaak is. Onlangse vloede wat plaasgevind het na die implementering van die beleid, het steeds van tyd tot tyd gelei tot noemenswaardige oorstromings van residensiële eiendomme, en kommer is uitgespreek deur 'n paar belanghebbende partye oor die doeltreffendheid van die strategie vir die bestuur. Daar is verder kommer uitgespreek oor die langtermyn welstand van die stelsel uit 'n ekologiese oogpunt. Historiese data toon 'n beduidende verandering in soutvlakke sedert die implementering van die bestuurstrategie met ‘n negatiewe langtermyn uitwerking op die stelsel. In hierdie studie is daar derhalwe numeriese modelle opgestel en toegepas ten einde die doeltreffendheid van die huidige bestuur van die beleid te bepaal, asook om die vloedvlakke te herbereken en te analiseer na aanleiding van 'n aantal voorgestelde scenario's. Langtermyn soutgehalte veranderinge is ook ontleed in 'n poging om die soutgehalte verspreiding deur die hele stelsel beter te verstaan, deur gebruik te maak van uiterste hipotetiese gevalle. Deur die ontleding van die simulasie resultate, is daar tot die gevolgtrekking gekom dat vloedwatervlakke in die Touwsrivier-monding byna heeltemal afhanklik was van die grootte van die Touwsrivier vloed en die aanvanklike hoogte van die sandbank by die riviermond. Watervlakke in die kusmere is egter byna heeltemal afhanklik van die hoeveelheid afloop na die mere en die aanvanklike watervlakke. Die huidige bestuursplan, wat slegs ‘n kunsmatige manipulasie van die sandbank by die riviermond behels, het dus 'n redelik onbeduidend invloed op die vloedwatervlakke wat in die kusmere bereik is. Daar is verder tot die gevolgtrekking gekom dat die konstruksie van die voorbereidende kanaal 'n uiters belangrike aspek van die huidige bestuursplan is, en dat die afskraping van die sandbank alleen oneffektief sou wees om die risiko van residensiële oorstroming langs die oewer van die Touwsrivier uit te skakel. Die soutgehalte modelleringstudie verskaf 'n eerste aanduiding van die soutgehalte eienskappe binne die stelsel. Daar is gevind dat die penetrasie van seewater in die stelsel minder prominent was as in die watermassas verder van die see af, en dat daar 'n duidelike direkte verband is tussen die volume van die varswater wat direk invloei na 'n watermassa en die mate van soutgehalte variasie in daardie spesifieke watermassa. In watermassas waar hoë volumes varswater direk invloei soos die Touwsrivier-monding, is 'n groot mate van soutgehalte variasie sigbaar. In die watermassas waar geen varswater invloei nie, soos die Rondevlei, bly soutvlakke meer stabiel en is minder geneig om te wissel.

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Vorsatz, Jeanne Pauline. "Ecological role of estuarine brachyuran crabs in mangrove and salt marsh estuaries, Eastern Cape, South Africa". Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1108.

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Crabs are conspicuous inhabitants of temperate salt marshes and tropical mangroves and interact with their environment through several processes. However, detailed information on crab community processes is absent for most South African estuaries and nearshore coastal regions. This study evaluated the primary producers supporting crab species in the salt marsh dominated Swartkops estuary and the mangrove Mngazana estuary. Various methods estimating crab abundances were also assessed in different microhabitats and the larval distribution of crabs in the coastal zone was also investigated. Various methods for estimating crab abundance have been employed in the past, each with its inherent biases. The microhabitat of a mangrove forest in Australia was structurally altered by the manipulation of the litter, pneumatophores and the associated algae. These alterations did not affect the behavioural activity or the numbers of crabs recorded in any of the experimental treatments by either visual counts or pitfall traps. However, the number of crabs caught in the pitfall traps differed between the sites. Species-specific behaviour which was not investigated in this study may bias crab abundance estimates when using pitfall traps and therefore requires further investigation. Benthic consumers inhabiting shallow coastal environments may ultimately have the origin of their nutrition in a number of possible sources. Isotopic and gut content analysis of Thalamita crenata and juvenile Scylla serrata in the Mngazana estuary in South Africa revealed that these two portunids are able to share a habitat by resource partitioning. Differences were noted for species-specific utilization of primary producers not only between seasons within a site, but also between sites. This highlighted the use of locally produced primary producers sustaining food webs in estuaries. Mangrove production in the Mngazana estuary is very important and contributes to most of the carbon in the underlying sediments in the mangrove forest. However, the relatively large number of species and biomass encountered in this estuary may also be attributed to the fact that the different species are able to exploit of a number of different resources. The variation in stable isotope analysis of the different crab species throughout the estuary indicated that these crabs able to occupy the same habitat by feeding on a number of different resources and may preferentially select for a specific primary producer. A stable isotope of crabs in the salt marsh Swartkops estuary indicated that the dominant primary producer sustaining crab communities may even take place on a relatively smallscale. Sesarma catenata found at the inner marsh site recorded more depleted carbon signatures than those encountered in the other sites approximately 100 m away, and reflected signatures similar to the locally-encountered inner marsh plants. The relatively enriched nitrogen signatures of the anthropogenically-impacted Swartkops estuary is an indication of extensive inputs due to urbanization and industrialization, in contrast to the relatively pristine Mngazana estuary which exhibited low nitrogen signatures. Emphasis has been placed on the abiotic component of the exchange of nutrients and energy, although living organisms may also be transported, both actively and passively, between ecosystems. Little variation in either species composition or abundance was found between seasons for the larval distribution of brachyuran crabs on the east coast of South Africa. Due to the lack of published larval descriptions, larvae could not be identified to species level and it was therefore not possible to identify whether the larvae were hatched or spawned in an estuary or in a marine environment, or whether the larvae originated in the northern tropical regions. Frequent wind-reversals which are common in this region may retain larvae close inshore and supply the southern temperate locations with larvae from the northern locations. In conclusion, this study has shown that in highly productive systems with a number of potential primary producers, the crabs that inhabit the estuary show a marked diversity in resource utilization which could potentially allow a number of closely related species to occupy different trophic levels. This study also highlights the importance of locally produced sources in an estuary, which may occur on very small scales and this needs to be factored in with the design of any future stable isotope studies of this nature.

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Akoto, William. "Valuing preferences for freshwater inflows into selected Western and Southern Cape estuaries". Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/915.

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An estuary is the last stage of a river. It is where the river meets the sea. Estuaries are one of the most significant features of the South African coastline. In recent years, South Africa has witnessed an increase in the demand for freshwater for both industrial and domestic purposes. At the same time, there has been a gradual deterioration of river systems and their catchments. To add to this, there has been a gradual reduction in the amount of recorded rainfall, which is the primary source of freshwater for rivers. This has resulted in decreased freshwater inflow into estuaries, a situation which poses a serious threat to the biological functioning of these estuaries and the services rendered to its recreational users. A deterioration of estuary services reduces the yield for subsistence households and their appeal for recration. This study uses the contingent valuation method as its primary methodology to elicit users' willingness-to-pay to reduce the negative impacts of reduced freshwater inflow into selected western and southern Cape estuaries. Eight estuaries were selected for this study; the Breede, Duiwenhoks, Great Berg, Kleinemond West, Mhlathuze, Swartvlei and Olifants estuaries. The contingent valuation (CV) method is widely used for studies of this nature because of its ability to capture active, passive and non-use values. The CV method involves directly asking people how much they would be willing to pay for specific environmental services. In this case, users were asked what they would be willing to pay to sustain freshwater inflows into selected estuaries in order to prevent the negative impacts of reduced inflows. The travel cost method (TCM) was uesed to generate an alternative comparative set of values for the purposes of convergence testing. This is because convergence testing is highly desirable as a validity test for CV estimates.

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Arundel, Helen Patricia, i lswan@deakin edu au. "Invertebrate larval dynamics in seasonally closed estuaries". Deakin University. School of Ecology and Environment, 2003. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20061011.142951.

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Estuarine benthic assemblages are often numerically dominated by polychaetes. The limits of these populations are determined by larval, and probably to a lesser extent adult movement. A previous study (Newton 1996), indicated that planktonic polychaete larvae were very abundant over the summer months in the Hopkins River; however, the identification and source of these larvae was not known. Defining the extent of a population, and therefore the likelihood of that population recovering following a perturbation, is crucial for effective estuarine management. This study investigated both the likely source of the larvae, (i.e. estuarine or marine) and the extent of larval dispersal within and between estuaries by addressing the following questions: Which taxa produced the planktonic larvae? Are these taxa resident estuarine species? Are the larvae of different taxa evenly distributed within the estuary or do physicochemical parameters or other factors influence their abundance? Are the same larvae found in other estuaries along the coast? and Is there exchange of these larval taxa with the marine environment and other estuaries? Larvae were identified and described by culturing commonly occurring planktonic larvae until adult characteristics appeared. The spionids, Carazziella victoriensis and Prionospio Tatura, numerically dominated the plankton in the Hopkins and the spionid, Orthoprionospio cirriformia was recorded from the Hopkins, Curdies and Gellibrand estuaries. Two spionids, Carazziella sp. and Polydora sp. were identified from tidal waters. Mouth status and physicochemical conditions (salinity, temperature and dissolved oxygen) were monitored in each estuary. Whereas the Merri and Gellibrand estuaries were predominantly stratified over the sampling period, the Curdies was more often well mixed and the Hopkins varied from well mixed to stratified. The duration of mouth opening and hence the opportunity for larval exchange also varied in each estuary. The Merri River was closed for 13.5% of days over the study period, the Gellibrand River for 18.4%, the Hopkins River for 49% and the Curdies River for 71.0%. The distributions of larvae at spatial scales of metres, 100s of metres and kilometres were investigated within a single estuary. While the same larvae, C. victoriensis, P. Tatura and bivalve larvae, were found along the length of the Hopkins estuary the abundances varied at different spatial scales suggesting different processes were influencing the distribution of P. Tatura larvae, and C. victoriensis and bivalve larvae. The distribution of larvae between several estuaries was investigated by monitoring meroplankton at two sites at the mouth of each of the four estuaries approximately monthly (except for winter months). Different meroplanktonic assemblages were found to distinguish each estuary. Further, C. victoriensis and P. Tatura larvae were only recorded in the Hopkins but larvae of the spionid, Orthoprionopio cirriformia were detected in the Hopkins, Curdies and Gellibrand estuaries. The extent of larval exchange with other estuaries and the marine environment was determined by monitoring tidal waters. Settlement trays were also deployed to determine if larvae were moving into estuaries and settling but not recruiting. P. tatura larvae were not detected in the tidal waters of any estuary and while C. victoriensis and O. cirriformia were found in both flood and ebb tides there was no evidence of movement of theses taxa to other estuaries. Larvae of the spionids, Carazziella sp. and Polydora sp., were found in tidal waters of each estuary but were rarely detected in the plankton within the estuaries. Neither species was found as an adult in background cores from any estuary, nor with the exception of a few individuals in the Merri, were they detected in settlement trays in any estuary. I conclude that the source of the larvae of C. victoriensis, P. Tatura and O. cirriformia is estuarine and while C. victoriensis, and O. cirriformia move in and outh of the source estuary in tidal waters there was no evidence for movement to other estuaries. The spionids, Carazziella sp. and Polydora sp were considered to be marine and while they moved in and out of estuaries in tidal waters they did not usually settle in the estuaries. The results of this study are a crucial first step in the development of ecological models to better understand dispersal in seasonally closed estuaries that are typical of southern Australia. This study emphasises the unique physicochemical characteristics and biological assemblages within these estuaries and the need for estuarine management to reflect these differences.

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Stirling, James R. "Dynamical system models of patchiness in estuaries". Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/13623.

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We develop three models for the flow in an estuary. The first being a 2 1-dimensional time-periodic model of a flow in the vertical cross section. The second model adds a third un-coupled velocity field U, in the along-estuary direction. The final model is a 3 + 1-dimensional, fully-coupled, time-periodic flow. We study the transport of material in each model using what are called lobe diagrams. Such diagrams allow us to separate the flow into different regions and then calculate the transport of material between adjacent regions. We also study the presence and bifurcations of curves which form partial barriers (ie. cantori and barriers formed from segments of unstable and stable manifolds of hyperbolic periodic points) or complete barriers (ie. KAM curves and other invariant circles) to transport. We use these models to develop an understanding of both the mixing within the flow and the formation and leakage of patches of higher concentration within a cloud of pollution released into the estuary. We also study the time taken for particles to exit the bounds of the estuary. As a result we get an understanding of which regions of the flow flush pollution out of the estuary in the least time and out of which end of the estuary they flush the pollution. We apply this understanding, and that gained from studying the mixing and formation of patches, to the problem of the optimal discharge of effluent into an estuary.

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Mansi, Sadoniben E. "Heavy metals and their ecotoxicology in estuaries". Thesis, University of Essex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426006.

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Kogut, Megan Brook 1972. "Copper speciation in estuaries and coastal waters". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84844.

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Thesis (Ph. D .)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.
Includes bibliographical references.
The goals of this dissertation are to better understand the sources and the Cu binding ability of ligands that control Cu toxicity in estuaries and harbors, where elevated Cu concentrations have caused documented toxic effects on microorganisms, fish, and benthic fauna. I modified and improved a commonly used approach to determine metal speciation (competitive ligand exchange adsorptive cathodic stripping voltammetry, CLE-ACSV). Using this new approach to chemical Cu speciation and an old approach to physical Cu speciation (filtration), I show that riverine humic substances, filtrable, recalcitrant and light absorbing molecules from degraded plant material, can account for all of the Cu binding in the Saco River estuary. This finding directly supports the hypothesis that terrestrial humic substances might be the most important source of Cu ligands for buffering Cu toxicity in coastal locations with freshwater inputs. However, fieldwork in coastal waters with large inputs of both Cu and suspended colloids (Boston Harbor, Narragansett Bay, and two ponds on Cape Cod) shows that some Cu present in these samples is inert to our competitive ligand exchange method for at least 48 hours. These results support the hypothesis that a significant fraction of the Cu present in these samples is physically sequestered in colloidal material, with the remaining fraction complexed by humic substances. Previous studies of Cu speciation were not able to distinguish between strongly complexed Cu and inert Cu, and our analytical approach should be used further to determine the role of colloids in Cu speciation in all natural waters.
by Megan Brook Kogut.
Ph.D .

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Beck, Julia S. "Sediment transport dynamics in South African estuaries". Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1465.

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Thesis (PhD (Civil Engineering))--University of Stellenbosch, 2005.
Estuaries are complex water bodies and differ considerably from fluvial river systems. In estuaries the flow reverses regularly due to the tidal currents and flow depths depend primarily on the tides and not the flow. An estuary has two sources of sediment: the river during floods and the ocean that supplies marine sediment through littoral drift which is transported by tidal currents into the estuary. Oversimplified models cannot be used to investigate the hydrodynamics and geomorphology of an estuary due to its complexity. Sedimentation of South African estuaries has created several environmental and social problems. Sediment transport imbalances have been caused by changes in the river catchments such as increased sediment yields and flood peak attenuation due to dam construction. Historically floods used to flush estuaries to maintain the long-term sediment balance in the river-estuary system, but with reduced flood peaks, sediment transport capacities at the estuaries are reduced and flushing efficiency decreased, resulting in marine transport dominating in many estuaries. Two-dimensional (horizontal, 2DH) numerical models have been found to be appropriate tools for studying hydro- and sediment dynamics in SA estuaries. The modelling shows that the sediment balance in the estuary relies on a delicate balance between dominant flood and ebb flows. Although the models performed very well, there are still additional processes to include such as time varying roughness changes and cohesive sediments. For long-term and long reach simulations, onedimensional (or quasi-two-dimensional) models will also be required in future. Mathematical modeling can be used to simulate the flushing of sediments during floods, but attempts should be made to calibrate these models when adequate field data become available in the future. The modelling has shown that floods play a very important part in estuarine sediment transport processes. Physical modelling was undertaken of the breaching of an estuary mouth. The main aim was to illustrate the merits of breaching at higher water levels as well as to investigate the changes in the mouth during breaching. The data obtained from the experiments were used to calibrate and verify a mathematical model. Mathematical modelling of the breaching process at the Klein River estuary confirms what has been observed during numerous breachings in the field, i.e. that breaching at higher water levels and towards the southeast side is more effective. Sediment transport by both waves and currents was investigated. It was found that with increasing wave and stream power, sediment transport rates would increase if both waves and currents travelled in the same direction. In contrast, it seems that with the current direction opposing that of the waves, Hydraulics of Estuarine Sediment Transport Dynamics in South Africa iii greater wave heights resulted in lower sediment transport rates. A new sediment transport equation, based on stream power, wave power, as well as sediment size was calibrated and verified, and compared to the well-known Bijker formula.

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Alkhalidi, Mohamad. "Sediment transport in sandy estuaries at equilibrium". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010108.

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Yin, Yunzhu. "Morphodynamic response of estuaries to climate change". Thesis, Swansea University, 2018. https://cronfa.swan.ac.uk/Record/cronfa39604.

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Estuaries are one of the most important aspects of coastal systems globally. They are often hubs for human civilisation due to the socioeconomic advantages they offer. As they are highly vulnerable to natural forces, including tides, waves, surges and river discharges, it is essential to study the relationship between estuarine morphologies and these natural variables, which is crucial in order to assess estuarine evolution. The Deben Estuary (UK) has been selected as the case study in this study as its morphology has been significantly changed over time. It can be expected that the estuary will undergo significant morphodynamic changes under future climate change. The objective of this study is to investigate the morphodynamic responses of the estuary to the climate change in order to better understand the relationship between morphological change and climate change. A regional scale depth-averaged hydrodynamic and morphodynamic model Delft 3D was set up to the Deben Estuary, which incorporates wave propagation. The model was validated against measurements of water levels and waves before using it to simulate detailed scenarios. Then, the future climate projection data was used as the boundary conditions for the model scenarios. First, the calm weather conditions were considered since the model was run in long-term time scale. Then the episodic events were accounted for to investigate the impact of waves in future storms on the estuarine morphodynamics. The results show that future climate change will enforce different responses of morphodynamics at the estuary. Responses vary depending on whether natural forces are episodic or long term, and also according to different climate change scenarios, such as different emission scenarios. The comparison between the responses under the present and future conditions indicates that the estuary may undergo different evolution to what is historically observed.

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Owens, Peter H. "Mathematical modelling of sediment transport in estuaries". Thesis, University of Birmingham, 1986. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618340.

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Chege, Jedidah. "Valuing preferences for freshwater inflows into five Eastern Cape and Kwazulu-Natal estuaries". Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/932.

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An estuary, according to the National Water Act of 1998, is a partially or fully enclosed body of water which is open periodically or permanently to the sea within which the sea water can be diluted, to an extent that is measurable with freshwater from inland. Estuaries and the lands surrounding them are places of transition from land to sea, and from freshwater to saltwater. Although influenced by the tides, estuaries are protected from the full force of ocean waves, winds, and storms by the reefs, barrier islands, or fingers of land, mud, or sand that surround them. South Africa’s estuaries are important and irreplaceable habitats, especially for prawns, fish, wading birds and mangroves. They are home to numerous plants and animals that live in water that is partly fresh and partly salty. Estuaries are also homes to growing coastal communities as increasing number of people occupy watersheds. However, estuaries are also threatened. One of the threats is reduced river water inflow. This study applies the contingent valuation method (CVM) to elicit user’s willingness to pay to mitigate the negative impacts of reduced freshwater inflow into selected five Eastern Cape and Kwazulu-Natal estuaries: the Sundays, Gamtoos, Mdloti, Mgeni and Mvoti estuaries. In addition to the contingent valuation method, the travel cost method was used to generate comparative values. The contingent valuation method is a technique to establish the value of a good (or service) that is not bought or sold in an actual market. The CVM establishes the economic value of the good by asking the users of an environmental good to state their willingness to pay (WTP) for a hypothetical project to prevent, or bring about, a change in the current condition of the environmental good. The users’ WTP is aggregated to establish a total willingness to pay (TWTP) for the population of the users of the environmental good.

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Figueirêdo, Francileide Vieira [UNESP]. "Susceptibilidade a antimicrobianos e resistência plasmidial de cepas de Salmonella spp isoladas de dois estuários do Estado do Ceará, Brasil". Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/100206.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A salmonelose é uma das doenças de origem alimentar mais freqüente e considerada uma das zoonoses mais relevantes para a saúde pública em todo o mundo. A Organização Mundial de Saúde (OMS) assinalou aumento alarmante de estirpes de Salmonella resistentes aos antibióticos devido ao seu uso abusivo em criações intensivas, especialmente nas aquícolas. Diante do exposto, o escopo deste trabalho foi o de isolar e identificar a resistência plasmidial em bactérias do gênero Salmonella, em amostras de água de dois ambientes estuarinos, um do Norte (Acaraú) e outro do Sul (Jaguaribe) do Estado do Ceará, ambos com atividades de carcinicultura. Durante sete meses, de novembro de 2006 a maio de 2007, foram coletadas 84 amostras de água dos dois estuários. A pesquisa de Salmonella seguiu a metodologia do “Bacteriological Analytical Manual”. As salmonelas foram testadas quanto à susceptibilidade a dez antimicrobianos: Ácido nalidíxico, Ampicilina, Ciprofloxacina, Ceftriazona, Cloranfenicol, Gentamicina, Imipenem, Nitrofurantoína, Sulfametoxazol e Tetraciclina. A Concentração Inibitória Mínima dos antibióticos seguiu a técnica de macrodiluição em caldo. Em atividade de base, mediu-se o pH, a temperatura e a salinidade da água. Foram confirmadas 103 cepas de Salmonella, 90 no Rio Acaraú e 13 no Rio Jaguaribe, pertencentes aos sorovares: S. Newport, S. Saintpaul, S. Panama, S. Rubislaw, S Albany, S. Anatum, S. Corvallis, S. Madelia. O Rio Acaraú apresentou-se mais contaminado do que o Rio Jaguaribe, onde foram encontradas cepas resistentes a antimicrobianos, com um percentual de 25% para resistência plasmidial, e 75% para a cromossômica. Esses resultados ressaltam dois problemas de saúde pública: a presença de cepas de Salmonella resistentes e a possibilidade de contaminação humana pelo consumo dos crustáceos. Somado a isso,...
Salmonellosis is one of the most common foodborne diseases, was considered and the most important for public health authorities throughout the world. The World Health Organization (WHO) recently drew attention to the rapid increase in Salmonella strains resistant to antibiotics employed in farming activities, especially in aquaculture. Thus, the objective of this study was to test the antimicrobial susceptibility of Salmonella strains isolated from water samples collected in the estuaries of the Acaraú and Jaguaribe rivers (respectively in the north and south of Ceará State, Brazil), both of which are subject to extensive shrimp farming. Eighty-four samples were collected between November 2006 and May 2007. The susceptibility tests were performed following the guidelines of the Bacteriological Analytical Manual (BAM). The strains were exposed to 10 different antibiotics: nalidixic acid, ampicillin, ciprofloxacin, ceftriaxone, chloramphenicol, gentamicin, imipenem, nitrofurantoin, sulfamethoxazole and tetracycline. The minimum inhibitory concentration of the antibiotics was determined with the broth macrodilution method. In base activity, mensure the factores as Temperature, salinity and pH values were registered for all water samples. One hundred three Salmonella strains were isolated (Acaraú n=90; Jaguaribe n=13) belonging to the serotypes S. Newport, S. Saintpaul, S. Panama, S. Rubislaw, S Albany, S. Anatum, S. Corvallis and S. Madelia. Thus, the Acaraú river was more severely contaminated than the Jaguaribe river, where strains resistant to antimicrobial were found in a rate of 25% to plasmid resistance and 75% to chromosomal resistance. These results show up two problems of public health: the presence of resistant strains of Salmonella and the possibility of human contamination though crustacean consumption. In addition to this,...(Complete abstract click electronic access below)

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Batista, Filho Job Jesus. "A dinamica das aguas subterraneas no estuario do Rio Itanhaem, litoral sul do Estado de São Paulo". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287665.

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Orientador: Sueli Yoshinaga Pereira
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias
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Resumo: O presente trabalho estuda a interferência da maré nos aqüíferos costeiros, identificando alterações hidrodinâmicas e químicas em suas águas. A pesquisa foi realizada no estuário do rio Itanhaém, em duas localidades: no Sitio de Pesquisa, com 7 poços instalados, situados às margens do rio Acima, a 3,5 km do oceano, e no CePeRio - Centro de Pesquisa do Estuário do rio Itanhaém, com 1 poço, localizado a aproximadamente 1 km do oceano. O estudo foi executado em 3 etapas, buscando-se conhecer: a geologia dos aqüíferos, suas características físicas, químicas e geométricas. Para os aspectos hidrodinâmicos, englobaram-se o monitoramento do nível d'água superficial e subterrâneo e os cálculos dos parâmetros hidrodinâmicos, como: condutividade hidráulica, velocidade média linear e transmissividade. Para a hidroquímíca foram executadas coletas periódicas, a cada 45 minutos, análise dos parâmetros físicoquímicos: temperatura, pR, Eh, condutividade elétrica (CE), sólidos totais dissolvidos (STD) e salinidade. Foram coletadas amostras em cada etapa para se an$l.lisar a composição química das águas estudadas, quantificando-se os seguintes íons: Na, K, Si, Mg, Ca, Sr, Co, Mn, Cu, P, Zn, Pb, AI, Ba, Cd, N~, Fe, Cr, RC03-, F- ,cr ,Br- ,N ,S042- e PO/- . Os aqüíferos estudados, um livre e um confmado, são compostos de sedimentos arenosos de granulometria fina. O aqüífero confinado é composto de areia com lente df. conchas calcáreas, à profundidade de 20 metros. As águas superficiais monitoradas foram: as dos rios Acima, Itanhaém e do ribeirão Campininha, que margeiam as áreas estudadas. O aqüífero livre, formado por areia fina, e o rio Acima apresentam águas sulfatadas ou cloretadas sódicas. No aqüífero, o STD varia de 40 a 70 mg/L e o pH é ácido (entre 4 e 5); no rio, o STD varia de 90 a 5.900 mgIL e o pH de 6 a 7. O aqüífero confinado, com argila siltosa na sua base e conchas calcáreas na sua estrutura, apresenta águas bicarbonatadas sódicas, com STD variando de 310 a 2.000 mg/L e pH neutro (entre 6 e 7,5). O aqüífero livre, com condutividade hidráulica (10 de 10-4 m/s, possui influência direta das oscilações da maré, com uma variação de amplitude do nível d'água (NA) 5 vezes menor que a da maré; o aqüífero confinado, com K igual a 10-6 m/s, oscila 11 vezes menos que a maré, com maior variação de 1,4 m. A direção do fluxo hidrodinâmico no aqüífero livre é para NW e a do confinado é para WSW, ambos com descarga no rio Acima. O aqüífero livre tem velocidade média linear da ordem de 10-6 m/s e transmissividade de 205 m2/dia, e o confinado 10-8 m/s e 13 m2/dia. Apenas no aqüífero livre, durante subidas fortes da maré, o fluxo hidrodinâmico se altera, derivando para o norte. Hidroquimicamente, as águas subterrâneas variam pouco com a intrusão salina. No inverno, as águas superficiais são mais salobras que em outras épocas do ano, o que está associado a fatores como: a maré mafs alta e a pluviometria reduzida
Abstract: The present work studied the influence of the tide in the coastal aquifers by identifying hydrodynamic and chemical alterations in the aquifiers. The research was carried out in the Itanhaém river estuary in two localities: in the Sitio de Pesquisa with 7 installed wells situated on the banks of the Acima river, 3,5 km from the ocean, and in the CePeRio - Center of Research ofthe ltanhaém river estuary with 1 well located approximately 1 km from the oceano The study was executed in 3 stages that studied the geologic formations of the aquifers and their physical, chemical and geometric characteristics. The hydrodynamic aspects were studied by monitoring of the superficial and underground water leveI, and hydrodynamic parameters such as hydraulical condutivity, linear average velocity and transmissivity were determined. The hydrochemical part of the research was executed with periodic collections of samples every 45 minutes and analyzed for the physical chemical parameters of temperature, pH, Eh, electric condutivity (EC), total dissolved solids (TDS) and salinity. AIso, samples were collected for each stage of the study and analyzed for the following íons: Na, K; Si, Mg, Ca, Sr, Co, Mo, Cu, P, Zn, Pb, AI, Ba, Cd, Ni, Fe, Cr, HC03-, F- ,cr ,Br- ,N ,sot e P043- . The aquifers, one phreatic and one confined,rare both composites of fine sand sediments. The confined one is a sand layer with presences of limestone shells and has a depth of 20 meters. The surface waters were also monitored in the Acima river, the Campininha brook and the Itanhaém river, which border the study area. The phreatic aquifer is formed of fine sand and with the Acima river has sodium sulfated or chlorinated and sodium bicarbonated water. In the aquifer, the TDS varied between 40 and 70 mg/L and pH was acidic (between 4 and 5). In the river, the TDS varied from 90 to 5,900 mg/L and pH was 6 to 7. The confined aquifer, with silt clay and limestone shell, had sodic bicarbonated waters with the TDS varying from 310 to 2,000 mg/L and pH neutral (between 6 and 7,5). The phreatic aquifer with hydraulical condutivity (K) 10-4 m/s had a direct influence from tidal oscillations with a variation of phreatic leveI amplitude 5 times lesser than that of the tide. The confined aquifer with K of 10-6 m/s, oscillated 11 times less than the tide for variations of larger than 1,4 m. The hydrodynamic flow direction for the phreatic aquifer was to NW and for the confined one it was for WSW, both with discharges in the Acima river. The phreatic aquifer had linear average velocity of the order of 10-6 m/s with a transmissivity of 205 m2/day and for the confined the values were 10-8 m/s and 13 m2/day. In the phreatic aquifer the hydrodynamic flow was modified during strong flows of the tide northward. Hydrochemically, the groundwater varied slightly with saline intrusion. In the winter, the river had the biggest ionic concentrations in comparison to the other seasons which were associated with factors such as the tide being higher in and the low precipitation at that time of year
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências

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Nizoli, Erico Casare 1983. "Partição multi-elementar tempo-espacial na interface água intersticial-sedimento em estuário tropical impactado e procedimentos químico-analíticos para análise de metais em águas salinas". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287686.

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Orientador: Wanilson Luiz Silva
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Durante as últimas décadas, efluentes industriais têm sido lançados no sistema estuarino de Santos-Cubatão, onde os rios Cubatão e Morrão são os principais receptores das descargas industriais. Diversos estudos foram realizados nos sedimentos do rio Morrão, já sendo bem conhecida a geoquímica da concentração total dos elementos neste ambiente. Os elevados níveis de ferro e fósforo de origem antrópica nestes sedimentos colocam este ambiente em um patamar científico cujos processos físico-químicos dominantes ainda são desconhecidos. No presente estudo, buscou-se identificar os processos que ocorrem na partição água intersticial-sedimentos em ambientes estuarinos impactados e o papel que a alta concentração de ferro e fósforo desempenha na variabilidade geoquímica tempo-espacial desta partição. Para tanto, foram investigados a dinâmica multi-elementar nos sedimentos, nas águas intersticiais, características fisico-químicas, matéria orgânica, sulfetos volatilizados por acidificação (AVS) e metais simultaneamente extraídos (SEM), granulometria e mineralogia mensalmente durante o período de onze meses, em dois ambientes do rio Morrão, sistema estuarino de Santos-Cubatão. Adicionalmente, foi desenvolvido um dispositivo para amostragem temporal de água intersticial por equilíbrio difusivo com sistema de coleta de amostra/recarga e uma proposta de mini-coluna para extração em fase sólida para a determinação de metais por ICP-MS em águas salinas. Os resultados obtidos demonstraram que o amostrador de água intersticial por equilíbrio difusivo proposto neste estudo é adequado para o emprego em trabalhos onde se pretende coletar temporalmente água intersticial sem perturbar os sedimentos e onde há a necessidade de um maior volume de amostra, o que não pode ser conseguido empregando amostradores apresentados pela literatura com funcionamento semelhante. Os dados do estudo sobre extração em fase sólida para determinação de metais em águas salinas por ICP-MS demonstraram que a mini-coluna com resina quelante proposta neste trabalho é eficaz em remover a matriz salina, apresentando precisão e exatidão adequadas aos níveis de analito presentes nas amostras. Já os resultados obtidos no estudo sobre a partição água intersticial-sedimentos em ambientes estuarinos impactados mostraram a existência de variações geoquímicas espaço-temporais para elementos maiores, menores e traços nos sedimentos. Assinaturas geoquímicas discriminantes foram observadas entre as populações de amostras VG (sedimentos expostos durante menor maré - borda do canal) e CN (sedimentos permanentemente submersos). Foi observado ainda que os elementos estudados se agrupam (análise de componente principal - PCA) de acordo com três fontes distintas (natural, indústrias siderúrgica e de fertilizantes). Variação espacial e temporal também foi identificada para a água intersticial, indicando que a autigênese de vivianita e magnetita estão entre os principais fatores controladores dos metais na água intersticial nos diferentes ambientes. Fases secundárias sulfetos (AVS) também exercem ação controladora dos metais na interface sedimento-água intersticial. Contudo, magnetita e vivianita apresentam-se como importantes retentores de metais na fase sólida, cuja cristalização autigênica é decorrente de introdução antrópica de Fe e P em grande escala no ambiente sedimentar do estuário do rio Morrão
Abstract: During the last decades, industrial effluents have been discharged into the estuary of Santos-Cubatão, where Cubatão and Morrão rivers are the main receivers of industrial discharges. Several studies were made in sediments of Morrão River, being already well known the geochemistry of the total concentration of the elements in this environment. The high levels of iron and phosphorus of anthropogenic origin in sediments, putting the environment on a scientific level in which dominant physical and chemical processes are still unknown. In the present study, we sought to identify the processes that occur in the pore water-sediment partition in estuaries impacted and the role that the high concentration of iron and phosphorus plays in the time and spatial geochemical variability. Therefore, we investigated the multi-elemental dynamics in sediments, interstitial waters, physico-chemical, organic matter, AVS and SEM, particle size and mineralogy, monthly, during the period of eleven months, in two places of Morrão river, Santos-Cubatão estuarine system. Additionally, we developed a device for temporal sampling of interstitial water by diffusive equilibrium system with sampling/recharging and a proposal for a mini-column for solid phase extraction for the determination of metals by ICP-MS in saline waters. The results showed that the pore water sampler for diffusive equilibrium proposed in this study is suitable for employment in investigations where it is necessary to collect temporally pore water without disturbing sediment and when there is a need for a larger sample volume, which cannot be achieved by employing samplers presented in the literature that operate similarly. Data from the study of solid phase extraction for the determination of metals in saline waters by ICP-MS showed that the mini-chelating resin column proposed in this study is effective in removing the salt matrix, with adequate accuracy and precision levels of analyte present the samples. Since the results obtained in the study of the pore water-sediment partition in estuaries impacted showed the existence of spatial and temporal geochemical variations for major, minor and trace elements in sediments. Discriminant geochemical signatures were also observed among the sample populations VG (sediments exposed during low tide - canal edge) and CN (permanently submerged sediments). It was also observed that the studied elements are grouped (Principal component analysis - PCA) according to three separate sources (natural, steel and fertilizer industries). Spatial and temporal variation was also identified for the interstitial water, indicating that the authigenesis of vivianite and magnetite are the main controlling factors of metals in the pore water in different environments. Secondary sulfide phases (AVS) also exert controlling metals in the interface sediment-pore water. However, magnetite and vivianite present themselves as important scavengers of metals, which authigenic crystallization is due to anthropogenic introduction of Fe and P large-scale sedimentary environment in the Morrão estuary
Doutorado
Geologia e Recursos Naturais
Doutor em Ciências

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Allison, Jeffrey Garner. "Dynamics of estuarine microphytobenthos in a shallow water sand bottom habitat". [Pensacola, Fla.] : University of West Florida, 2006. http://purl.fcla.edu/fcla/etd/WFE0000004.

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Lima, Caroline Stefani da Silva. "Padrão de distribuição das assembleias de peixes juvenis em um estuário do semiárido do Brasil". Universidade Estadual da Paraíba, 2017. http://tede.bc.uepb.edu.br/jspui/handle/tede/2860.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Estuaries are dynamic coastal ecosystems in which the interaction between the hydrological regime and the mixing of fresh and oceanic waters creates a gradient of variables that reflect on the structure of the fish community, as well as their spatio- temporal pattern. These characteristics are used as filters, that is, determining factors that select species ecologically similar, hence producing different groups of species along an environmental gradient. These filters can act on hierarchical scales, partitioning the diversity of species within the components α (local diversity), β (variation of diversity between sites) and γ (regional diversity). Therefore, the aim of this study was to analyze the composition, structure, hierarchical partitioning and if beta diversity is determined either by turnover or nestedness of fish assemblages in the Mamanguape river estuary, influenced by hydrological changes (rainy and dry periods). The composition and structure of the estuarine fish assemblages were characterized by a few dominant species in numerical abundance and biomass, being these considered core species. In addition, abundance and diversity increased with the proximity to the ocean due to adequate salinity conditions and greater habitat availability in these areas. The catch of fish in the estuary was higher during the rainy season, related to the recruitment period of many species that coincide with the environmental changes. The Canonical Correspondence Analysis indicated salinity and chlorophyll-a as the main filters of the spatial distribution of fish assemblages, separating them along the three zones according to the osmoregulation capacity of each species and the availability of resources in the zones. In the analysis of the hierarchical partition of the fish assemblages, the dissimilarity of the species composition was higher in the upper level (β3), influenced mainly by the turnover in both hydrological periods, suggesting the importance of the environmental heterogeneity for the fish diversity in this estuary.
Estuários são ecossistemas costeiros dinâmicos cuja interação entre o regime hidrológico, entrada de água doces e oceânica cria um gradiente de variáveis ambientais que refletem na estrutura da comunidade de peixes, bem como no seu padrão de utilização espaço-temporal. Estas características ambientais podem atuar como filtros, ou seja, fatores determinantes que selecionam espécies ecologicamente similares, consequentemente produzindo diferentes grupos de espécies ao longo de um gradiente ambiental. Tais filtros podem agir em escalas hierárquicas, particionando a diversidade de espécies dentro dos componentes α (diversidade local), β (variação da diversidade entre locais) a γ (diversidade regional). Portanto, o objetivo desse estudo foi analisar a composição, estrutura, bem como, partição hierárquica e se diversidade β das assembleias de peixes é determinada por turnover ou aninhamento no estuário do rio Mamanguape – PB, influenciada pelas mudanças hidrológicas (período chuvoso e seco). A composição e estrutura das assembleias de peixes estuarinas foram representadas por poucas espécies dominantes em abundância numérica e biomassa, sendo essas considerada core species. Além disso, a abundância e diversidade aumentaram com a proximidade com o oceano, devido às condições adequadas de salinidade e maior disponibilidade de habitats nestas áreas. A captura de peixes no estuário foi maior durante o período chuvoso, relacionadas ao período de recrutamento de muitas espécies que coincidem com as mudanças ambientais. A análise de correspondência canônica indicou a salinidade e a clorofila-a como os principais filtros da distribuição espacial das assembleias de peixes, separando-as ao longo das três zonas em função da capacidade de osmorregulação de cada espécie e a disponibilidade de recursos nas zonas. Na análise da partição hierárquica das assembleias de peixes, a dissimilaridade da composição de espécies foi maior no nível superior (β), influenciada principalmente pelo turnover em ambos os períodos hidrológicos, sugerindo a importância da heterogeneidade ambiental para a diversidade de peixes nesse estuário.

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Vosloo, Mathys Christiaan. "Network analysis of trophic linkages in two sub-tropical estuaries along the South-East coast of South Africa". Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1010966.

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Estuaries are some of the most productive yet threatened ecosystems in the world. Despite their importance they face significant threats through changes to river flow, eutrophication, rapid population growth long the caost and harvesting of natural resources. A number of international studies have been conducted investigating the structure and functioning of an array of ecosystems using ecological network analysis. Energy flow networks have been contsructed for coastal, lagoonal, intertidial and, most notably, permantently open estuaries. Despite the valualble insights contributed by these and other studies, a lack of information on the majority of estuarine ecosystems exists.

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Landin, Charles Melchor. "Dissolved gaseous mercury behavior in shallow water estuaries". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2098.

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Conrad, Sarah. "Origin of Iron Isotope Signatures in Boreal Estuaries". Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17896.

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The geochemistry of iron (Fe) during freshwater transport and estuarine mixing has been investigated. Espescially the changes in the Fe-isotope signature have been studied. The fate of Fe-isotopes during estuarine mixing has been poorly studied. Sampling was performed in Kalix River, Kalix and Råne estuary, and in the open Bothnian Bay, Northern Baltic Sea. Water samples were filtered with 0.22 μm membrane filters. Both particulate (> 0.22 μm) and colloidal fractions (< 0.22 μm) were analyzed. Iron particles and colloids, with a negative Fe-isotope signature, are formed during spring flood in forested catchments. These Fe complexes are associated with organic carbon (OC), and probably have a mixed oxidation state (Fe(II,III)-OC). Negative colloids are labile and flocculate and/or oxidize during riverine transport. Therefore, no negative colloids are detectable in the estuaries of the open Bothnian Bay. Within the estuaries two types of ˜56Fe signatures were measured: negative particles and positive colloids. The open Bothnian Bay shows a third distinct group of positive particles. This group mirrors the rapid removal of Fe colloids and particles at low salinities. Most of the Fe has been removed from surface water at salinities below 1.0 psu. Data in this study show that the Fe-isotopes can be used to trace the origin and cycling of iron particles and colloids in the boreal landscape.
Godkänd; 2014; 20141119 (sarcon); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Sarah Conrad Ämne: Tillämpad geologi/Applied Geology Uppsats: Origin of Iron Isotope Signatures in Boreal Estuaries Examinator: Professor Johan Ingri, Institutionen förs amhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Professor Magnus Mörth, Institutionen för geologiska vetenskaper, Stockholms Universitet Tid: Onsdag den 17 december 2014 kl 10.00 Plats: F531, Luleå tekniska universitet

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Claus, Sonia Carmel, University of Western Sydney, of Science Technology and Environment College i of Science Food and Horticulture School. "Heavy metals in biota from temperate Australian estuaries". THESIS_CSTE_SFH_Claus_S.xml, 2003. http://handle.uws.edu.au:8081/1959.7/503.

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The detection of anthropogenic impacts in our estuaries has become a critical social, political and scientific concern in recent years. Work has focussed on the effects of these impacts on the spatial and temporal patterns of biotic assemblages and searched for bioindicators and biomarkers of pollutants that may act as early warning signs. The estuaries in temperate Southeastern Australia have a diversity of biotic assemblages living in the soft sediment. One of the most abundant macroinvertebrates is the little studies mussel, Xenostrobus securi that is found living with an assemblage of benthic biota including amphipods, crabs, isopods and tanaids, bivalves and gastropods. Two commercial fish species bream and mullet also inhabit these estuaries. Numerous stormwater drains can be found entering the estuaries through the mangrove forests lining the shores. Along with inputs of freshwater, stormwater drains are thought to be responsible for the entry of heavy metals into estuaries. These heavy metals have the potential to alter the patterns of biotic assemblages and bioaccumulate in the tissues of miacroinvertebrates, mussels and fish living within temperate estuaries. Over the time of this study the concentrations of heavy metals in the sediment tissues and shell of X.Securis varies spatially and temporally. Although this study adds substantially to current knowledge there is still more that is needed to establish X. Securis as a bioindicator. Questions remain about uptake, depuration and response to environmental gradients of heavy metals in X. Securis. Before X Securis can be used routinely in monitoring heavy metal contamination these questions need to be further investigated
Doctor of Philosophy (PhD)

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Claus, Sonia Carmel. "Heavy metals in biota from temperate Australian estuaries /". View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20051013.092820/index.html.

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Thesis (Ph.D.) -- University of Western Sydney, 2003.
"Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney Hawlesbury" Bibliography : leaves 245-278.

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Turner, Andrew. "Chemical dynamics in North Sea estuaries and plumes". Thesis, University of Plymouth, 1990. http://hdl.handle.net/10026.1/1684.

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Observational and experimental studies have been undertaken in the southern North Sea environment, including five major estuaries (Humber, Thames, Scheldt, Weser and Elbe), with the aim of elucidating the mechanistic and kinetic details of trace metal reactivity required for the refinement of pollutant transport models. The results of a systematic investigation of suspended particle characteristics (BET specific surface area and porosity, carbon content. Fe and Mn oxide coatings) indicated that, although there exists significant yet explicable variability among the North Sea estuaries, such compositional factors do not exert an observable influence on solid-solution interactions. Furthermore, chemical reactivity was not usually demonstrable from observations of leachable particulate trace metals as phase interactions Impart relatively little influence on their concentrations; particulate metal distributions therefore generally conformed with mixing of fluvial and marine material unless perturbed by major anthropogenic sources as in the Humber. Solid-solution redistributions were revealed by following the partitioning of artificial radiotracers in a series of carefully controlled experiments in which salinity and suspended solids concentration gradients were simulated by mixing river and sea water end-member samples. Relationships between salinity and the solid:solution concentration of radiotracers as quantified by a distribution coefficient ( K Q ) indicated substantial desorption from particles of ^^®Cd and ^"^^Cs. conservative behaviour of ^ ^ Z n , and oxidative removal from solution of ^^Mn. Radiochemical techniques applied in situ to study solid-solution partitioning in the southern North Sea established a more significant role of particle composition (in particular, estuarine-derived versus plankton-rich material) in regulating trace metal behaviour in offshore waters. This finding was corroborated by distinct seasonal contrasts in measured particulate metal concentrations; whereas most metals (Fe, Mn. Cu, Pb, Zn) were enriched during winter when detrital and terrigenous components from fluvial/resuspension inputs dominate. Cd was elevated during summer in tandem with amplification of the biomass. These results provide a valuable basis for both future long-term pollutant monitoring programmes, and the conceptual development of estuarine chemical flux models, specifically the incipient Plymouth Marine Laboratory model of the Humber plume.

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Tyler, Andrew O. "The distribution and reactivity of organochlorines in estuaries". Thesis, University of Plymouth, 1999. http://hdl.handle.net/10026.1/1673.

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In February 1997, the Governing Council of the United Nations Environment Programme initiated a protocol to reduce the risks to human health and the environment arising from persistent organic pollutants. The initial list of 12 families of organochlorine pollutants included polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) selected for their persistence, bioaccumulation capacity and toxicity. The aim of this work was to further understanding of the behaviour of these organochlorines (OCs) in estuarine systems. Field surveys were conducted at UK estuarine (Humber, Clyde and Dee) and coastal locations. Sediments were analysed for OCs and a range of chemical and physicochemical properties (trace metals, organic carbon content, specific surface area). Hydrographic measurements were also made to assist in defining the estuarine environment. Concentrations of PCDD/DF on a dry weight basis ranged from non-detectable (n.d.) to 11100 pg g"^ and PCB from n.d. to 3000 ng g Estuarine OC contamination was generally elevated above coastal waters concentrations. The distribution of OCs was studied to determine the extent of source, compound physicochemical, and particulate geochemical influences. In the Clyde estuary some source-related effects were observed but in the Humber estuary, characterised by highly dynamic conditions, these were masked by mixing of sediments. The characteristics of the sorbent were found to be of key importance with the content and nature of particulate organic carbon being the major control. To further understand the sorption behaviour of OCs, partitioning experiments were conducted with ^"C analogues of the compounds under realistic estuarine gradient conditions (K^ range from 2.4 x 10** to 49.4 x 10"* for TCB and 23.1 x 10Mo 313 x 10^ for TCDD). Particle concentration was found to be of key importance and it was concluded that this effect was transferable to environmental situations. Salinity was found to be a minor influence on partitioning behaviour. Development of sorption sub-models and their incorporation into an integrated estuarine contaminant transport model was demonstrated. A particle interaction-based sorption model was shown to only partially account for the observed partitioning behaviour; inclusion of an irreversibly adsorbed fraction may more adequately represent estuarine partitioning. Riverine and outfall discharges were simulated in the integrated contaminant transport model to demonstrate the influence of tidal hydrodynamics, sediment dynamics and variable partitioning applied to the Humber estuary.

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Whyte, Kenneth K. "Entrainment and mixing in rivers, estuaries and reservoirs". Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400129.

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Ernstberger, Helmut Hans. "The fate of terrestrially derived phosphorus in estuaries". Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287622.

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In this study the phase distribution of phosphorus (P) is examined in 7 Scottish East Coast rivers. Rivers with contrasting catchment properties were selected, including pristine highland rivers, lowland rivers with agricultural land use and a range of intermediate rivers. Suspended particulate matter (SPM) was rich in organic P and had total P contents in the range of 0.1 to 1%. Highest total P contents of particles were observed for the river richest in dissolved P. The pristine highland systems showed the lowest total P contents. Large increases in exchangeable P in summer were partly attributable to the presence of phytoplankton. Phytoplankton accounted for less than half and more typically around 20% of organic carbon in SPM. The remainder is likely to consist largely of amorphous, humic substances. Sorption properties (e.g. EPC₀, equilibrium phosphate concentration at zero adsorption) of SPM were examined using adsorption isotherms. Particle concentrations for sorption experiments were kept low (ca. 200 mg/l) to allow extrapolations to natural conditions. SPM from highland rivers showed the largest affinity for P. Lowland rivers displayed a comparatively low affinity for P. EPC₀ values of SPM closely reflected soluble reactive phosphorus concentrations in river water. SPM from highland and lowland rivers showed consistent differences in organic carbon content. Organic carbon content of SPM was correlated to sorption parameters of SPM. The sorption parameters of intermediate rivers could be explained by mixing particles of different affinity, using organic carbon contents to trace the proportions of particle mixing. Under estuarine conditions the affinity of fluvial SPM for P decreases. The magnitude of the change is insufficient to cause desorption in the pristine highland rivers. Up to 80-fold increases in EPC₀ were observed for the remaining rivers suggesting desorption takes place in the estuary.

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Comber, Sean David William. "The biochemical control of arsenic in certain estuaries". Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280907.

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Ruhl, Nathan A. "The Lotic-Lentic Gradient in Reservoirs and Estuaries". Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1339177201.

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Patra, Rashmi Ranjan. "Sediment management in low-energy estuaries Loxahatchee, Florida /". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002800.

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Todeschini, Ilaria. "Long-term morphological response of tide dominated estuaries". Doctoral thesis, Università degli studi di Trento, 2006. https://hdl.handle.net/11572/368383.

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Most estuaries of the world are influenced by tides. The tidal action is a fundamental mechanism for mixing river and estuarine waters, resuspending and transporting sediments and creating bedforms. The planform of tide-dominated estuaries is characterized by a funnel-shaped geometry with a high width-to-depth ratio. The width of the estuarine section tends to decrease rapidly upstream, following an exponential law and the bottom slopes are generally non-significant. In this thesis the long-term morphological evolution of tide-dominated estuaries is investigated through a relatively simple one-dimensional numerical model. When a reflective barrier condition is assigned at the landward boundary, the morphological evolution of an initially horizontal tidal channel is characterized by the formation of a sediment wave that migrates slowly landward until it leads to the emergence of a beach. The bottom profile reaches a dynamical equilibrium configuration which has been defined as the condition in which the tidally averaged sediment flux vanishes or, alternatively, the bottom elevation attains a constant value. For relatively short and weakly convergent estuaries, the beach is formed at the landward end of the channel, due to the reflective barrier chosen as boundary condition, and the equilibrium length coincides with the distance of such boundary from the mouth. When the above distance exceeds a threshold value, which decreases for increasing values of the degree of convergence of the channel, the beach forms within an internal section of the estuary and the final equilibrium length is much shorter and mainly governed by the convergence length. The final equilibrium length of the channel is found to depend mainly on two parameters, namely the physical length of the channel and the degree of convergence. Moreover, if a condition of vanishing sediment flux from the outer sea during the flood phase is imposed, a larger scour in the seaward part of the estuary is observed, though the overall longitudinal bottom profile does not differ much from that corresponding to a sediment influx equal to the equilibrium transport capacity at the mouth. This fixed banks model is not able to explain this typical funnel shape; furthermore, the bottom slopes obtained with this models are quite large if compared with the mild slopes of real tidedominated estuaries. For these reasons, the problem has been analysed to understand the reason why tidal channels are convergent and to define the conditions under which the exponential law for width variation, which is so often observed in nature, is reproduced. The long-term evolution of the channel cross-section is investigated allowing the width to vary with time. The one-dimensional model is expanded by considering a simple way to take the banks erosion into account. A strongly simplified approach is adopted, whereby only the effects related to flow and sediment transport processes within the tidal channel are retained and further ingredients, like the control exerted by tidal flats or the direct effect of sea currents in the outer part of the estuary, are discarded. The lateral erosion is taken into account and computed as a function of bed shear stress, provided it exceeds a threshold value within the cross section. The effect of different initial and boundary conditions on the widening process of the channel is tested, along with the role of the incoming river discharge. Another problem, which is somehow analogous to that of the cross-section evolution, is tackled: a part of a tidal flat dissected by a series of parallel channels is considered and the response of the system induced by a modification of the depth of the channels is studied. In particular, the aim is to assess whether the increase of the depth of one channel, starting from an equilibrium configuration, causes deposition in the others inducing their closure. The evaluation of the morphological effect of a depth variation in one of channel upon the other channels is quite a relevant task, because the stability of salt marshes and lagoons is intrinsically related to the stability of the hydrodynamic functionality of the channels. A result of this analysis is the determination of a characteristic distance between the channels to have mutual influence. It is found that this distance scales with the root of the longitudinal length of the flat; thus, a scaledependent spacing is expected in tidal networks.

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46

Todeschini, Ilaria. "Long-term morphological response of tide dominated estuaries". Doctoral thesis, University of Trento, 2006. http://eprints-phd.biblio.unitn.it/614/1/Todeschini_Tesi_Dottorato.pdf.

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Most estuaries of the world are influenced by tides. The tidal action is a fundamental mechanism for mixing river and estuarine waters, resuspending and transporting sediments and creating bedforms. The planform of tide-dominated estuaries is characterized by a funnel-shaped geometry with a high width-to-depth ratio. The width of the estuarine section tends to decrease rapidly upstream, following an exponential law and the bottom slopes are generally non-significant. In this thesis the long-term morphological evolution of tide-dominated estuaries is investigated through a relatively simple one-dimensional numerical model. When a reflective barrier condition is assigned at the landward boundary, the morphological evolution of an initially horizontal tidal channel is characterized by the formation of a sediment wave that migrates slowly landward until it leads to the emergence of a beach. The bottom profile reaches a dynamical equilibrium configuration which has been defined as the condition in which the tidally averaged sediment flux vanishes or, alternatively, the bottom elevation attains a constant value. For relatively short and weakly convergent estuaries, the beach is formed at the landward end of the channel, due to the reflective barrier chosen as boundary condition, and the equilibrium length coincides with the distance of such boundary from the mouth. When the above distance exceeds a threshold value, which decreases for increasing values of the degree of convergence of the channel, the beach forms within an internal section of the estuary and the final equilibrium length is much shorter and mainly governed by the convergence length. The final equilibrium length of the channel is found to depend mainly on two parameters, namely the physical length of the channel and the degree of convergence. Moreover, if a condition of vanishing sediment flux from the outer sea during the flood phase is imposed, a larger scour in the seaward part of the estuary is observed, though the overall longitudinal bottom profile does not differ much from that corresponding to a sediment influx equal to the equilibrium transport capacity at the mouth. This fixed banks model is not able to explain this typical funnel shape; furthermore, the bottom slopes obtained with this models are quite large if compared with the mild slopes of real tidedominated estuaries. For these reasons, the problem has been analysed to understand the reason why tidal channels are convergent and to define the conditions under which the exponential law for width variation, which is so often observed in nature, is reproduced. The long-term evolution of the channel cross-section is investigated allowing the width to vary with time. The one-dimensional model is expanded by considering a simple way to take the banks erosion into account. A strongly simplified approach is adopted, whereby only the effects related to flow and sediment transport processes within the tidal channel are retained and further ingredients, like the control exerted by tidal flats or the direct effect of sea currents in the outer part of the estuary, are discarded. The lateral erosion is taken into account and computed as a function of bed shear stress, provided it exceeds a threshold value within the cross section. The effect of different initial and boundary conditions on the widening process of the channel is tested, along with the role of the incoming river discharge. Another problem, which is somehow analogous to that of the cross-section evolution, is tackled: a part of a tidal flat dissected by a series of parallel channels is considered and the response of the system induced by a modification of the depth of the channels is studied. In particular, the aim is to assess whether the increase of the depth of one channel, starting from an equilibrium configuration, causes deposition in the others inducing their closure. The evaluation of the morphological effect of a depth variation in one of channel upon the other channels is quite a relevant task, because the stability of salt marshes and lagoons is intrinsically related to the stability of the hydrodynamic functionality of the channels. A result of this analysis is the determination of a characteristic distance between the channels to have mutual influence. It is found that this distance scales with the root of the longitudinal length of the flat; thus, a scaledependent spacing is expected in tidal networks.

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47

Cappuci, Sergio. "The stability and evolution of an intertidal flat in Venice Lagoon, Italy". Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250074.

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Cowie, Meredith. "Environmental flows, health and importance of macrophytes in the estuaries of water management area 11". Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/7930.

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Estuaries require sufficient quantity, quality and appropriate timing of freshwater inflow, referred to as environmental flow requirements, to ensure adequate health and functioning. In South Africa the environmental flow requirements of estuaries is determined using Resource Directed Measures (RDM). The present health and importance of an estuary must be considered when determining the ecological flow required to maintain an estuary in its desired state. An Estuarine Health Index that quantifies changes in abiotic and biotic components from natural conditions to present day is used. Health of biotic components is assessed according to changes in species richness, abundance and community composition. There has, however, been debate regarding the calculation of these attributes. In particular, for macrophytes, the inclusion of all habitat within the Estuarine Functional Zone (i.e. 5 m topographical contour) would affect the health and changes over time determined in past assessments. This is due to different areas being included as different areas would be included The aim of this study was to test the validity and suggest improvements to South Africa’s RDM macrophyte health score determination. The health of macrophytes were assessed at varying levels of intensity from desktop studies to thorough field studies. Rapid field studies provided a visual estimate of macrophyte health; while the intermediate and comprehensive assessments quantified change by mapping the distribution of macrophyte habitats from aerial photographs. These approaches were applied to the 64 estuaries within the Mvoti-Mzimkulu Water Management Area (WMA 11), situated in KwaZulu-Natal (KZN) on the subtropical east coast. Historically, these estuaries have supported restricted macrophyte habitats. Consequently, estuaries that presently or historically supported range limited habitats such as mangroves and swamp forest are considered important. Submerged macrophytes are scarce in KZN estuaries due to siltation and low turbidity and thus estuaries supporting this macrophyte habitat are also important. Based on available literature important estuaries were highlighted and selected for field studies. Transects spanning from the estuary water channel to the boundary of the EFZ provided a generalised distribution of KZN vegetation along an elevation gradient. The transition from estuarine to terrestrial vegetation can be used to improve the current EFZ boundaries, as estuarine area has been found to occur outside of the 5 m contour in some estuaries. Results from the desktop assessment indicated that most of the estuaries are moderately modified. There was a 50 % similarity in the macrophyte health scores determined by the desktop assessment to the 2011 National Biodiversity Assessment (NBA). Field studies mostly confirmed the desktop assessment aside from seven estuaries that had different scores. There has been a significant loss of macrophyte habitat with 100% loss of certain habitats from 9 of the 22 estuaries for which there were field assessments. Submerged macrophytes were not found at any of the estuaries that were assessed in the field. Black mangroves, Bruguiera gymnorrhiza (L.) Lam., were rediscovered at Ngane Estuary, however the few individuals could not be considered a ‘mappable’ community (i.e. <0.5 ha). Mtamvuna and Mkomazi estuaries both supported small stands of mangroves that, compared to data from 2006, appeared healthy. Macrophyte habitats and surrounding coastal forest matched the species composition described in the Vegetation Map of South Africa. The freshwater mangrove or Powder puff tree, Barringtonia racemosa (L.) Roxb, was not abundant in the estuaries. It was only found at four (Damba, Fafa, Little Amanzimtoti and Mvoti) of the estuaries that were assessed in the field. Important estuaries, from a botanical perspective, included some of the larger estuaries such as Mgeni, Durban Bay and Sipingo. Smaller, healthier estuaries that presently support mangrove and swamp forest habitat were also identified as important from a botanical perspective. Macrophyte habitats have mainly been lost due to non-flow related pressures. Sugarcane cultivation occurred within the floodplain of 25% of the estuaries. Nutrient enrichment was evident for 12.5% of the estuaries and reed encroachment was evident for 27% of estuaries for which there were field assessments. Development, aside from the N2 road bridges, was evident for 40% of the estuaries assessed in the field. Invasive plant species, including aquatic invasive plants, were present in all estuaries assessed in the field. The extent of invasive plant species was related to the degree of disturbance and surrounding land use pressures. The Mkomazi and Mvoti estuaries that were assessed at a comprehensive level, as they have earmarked for further water abstraction, had the poorest macrophyte health scores. The macrophyte health of these estuaries was much lower than previously determined by the NBA. The decline in health was attributed to the removal of macrophyte habitat for sugarcane cultivation and development as well as displacement by invasive plant species. The areas covered by the macrophyte habitats also differed from the NBA highlighting the importance of updated mapping and ground truthing. Largely differing macrophyte health scores were produced when attributes were calculated using different combinations of macrophyte habitats. Results indicate that only macrophyte habitats and no other floodplain vegetation should be included when calculating abundance. All macrophyte habitats, physical habitats and floodplain should be incorporated when calculating community composition. The minimum of these attributes is used as the overall macrophyte health score as a precautionary approach is followed. Scoring of health is subjective and the only benchmark for determining the most appropriate method is comparion with previous RDM studies. This study illustrates the need for a standardised RDM scoring method that is presented in a manner that ensures the same results irregardless of the speciliast conducting the study. The updated estuary health and importance scores for WMA 11 are necessary to inform management, particularly as few of the estuaries receive formal protection. In conclusion, this study contributed to the limited knowledge of the estuaries of WMA 11 and assisted in determining appropriate methods for assessing the health and importance of estuary macrophytes.

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Figueirêdo, Francileide Vieira. "Susceptibilidade a antimicrobianos e resistência plasmidial de cepas de Salmonella spp isoladas de dois estuários do Estado do Ceará, Brasil /". Jaboticabal : [s.n.], 2008. http://hdl.handle.net/11449/100206.

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Resumo: A salmonelose é uma das doenças de origem alimentar mais freqüente e considerada uma das zoonoses mais relevantes para a saúde pública em todo o mundo. A Organização Mundial de Saúde (OMS) assinalou aumento alarmante de estirpes de Salmonella resistentes aos antibióticos devido ao seu uso abusivo em criações intensivas, especialmente nas aquícolas. Diante do exposto, o escopo deste trabalho foi o de isolar e identificar a resistência plasmidial em bactérias do gênero Salmonella, em amostras de água de dois ambientes estuarinos, um do Norte (Acaraú) e outro do Sul (Jaguaribe) do Estado do Ceará, ambos com atividades de carcinicultura. Durante sete meses, de novembro de 2006 a maio de 2007, foram coletadas 84 amostras de água dos dois estuários. A pesquisa de Salmonella seguiu a metodologia do "Bacteriological Analytical Manual". As salmonelas foram testadas quanto à susceptibilidade a dez antimicrobianos: Ácido nalidíxico, Ampicilina, Ciprofloxacina, Ceftriazona, Cloranfenicol, Gentamicina, Imipenem, Nitrofurantoína, Sulfametoxazol e Tetraciclina. A Concentração Inibitória Mínima dos antibióticos seguiu a técnica de macrodiluição em caldo. Em atividade de base, mediu-se o pH, a temperatura e a salinidade da água. Foram confirmadas 103 cepas de Salmonella, 90 no Rio Acaraú e 13 no Rio Jaguaribe, pertencentes aos sorovares: S. Newport, S. Saintpaul, S. Panama, S. Rubislaw, S Albany, S. Anatum, S. Corvallis, S. Madelia. O Rio Acaraú apresentou-se mais contaminado do que o Rio Jaguaribe, onde foram encontradas cepas resistentes a antimicrobianos, com um percentual de 25% para resistência plasmidial, e 75% para a cromossômica. Esses resultados ressaltam dois problemas de saúde pública: a presença de cepas de Salmonella resistentes e a possibilidade de contaminação humana pelo consumo dos crustáceos. Somado a isso,...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Salmonellosis is one of the most common foodborne diseases, was considered and the most important for public health authorities throughout the world. The World Health Organization (WHO) recently drew attention to the rapid increase in Salmonella strains resistant to antibiotics employed in farming activities, especially in aquaculture. Thus, the objective of this study was to test the antimicrobial susceptibility of Salmonella strains isolated from water samples collected in the estuaries of the Acaraú and Jaguaribe rivers (respectively in the north and south of Ceará State, Brazil), both of which are subject to extensive shrimp farming. Eighty-four samples were collected between November 2006 and May 2007. The susceptibility tests were performed following the guidelines of the Bacteriological Analytical Manual (BAM). The strains were exposed to 10 different antibiotics: nalidixic acid, ampicillin, ciprofloxacin, ceftriaxone, chloramphenicol, gentamicin, imipenem, nitrofurantoin, sulfamethoxazole and tetracycline. The minimum inhibitory concentration of the antibiotics was determined with the broth macrodilution method. In base activity, mensure the factores as Temperature, salinity and pH values were registered for all water samples. One hundred three Salmonella strains were isolated (Acaraú n=90; Jaguaribe n=13) belonging to the serotypes S. Newport, S. Saintpaul, S. Panama, S. Rubislaw, S Albany, S. Anatum, S. Corvallis and S. Madelia. Thus, the Acaraú river was more severely contaminated than the Jaguaribe river, where strains resistant to antimicrobial were found in a rate of 25% to plasmid resistance and 75% to chromosomal resistance. These results show up two problems of public health: the presence of resistant strains of Salmonella and the possibility of human contamination though crustacean consumption. In addition to this,...(Complete abstract click electronic access below)
Orientador: Julieta Rodini Engracia de Moraes
Coorientador: Regine H. S. dos Fernandes Vieira
Banca: Fabiana Pilarski
Banca: Angela Cleusa de Fátima Banzatto de Carvalho
Banca: Gilson Pereira de Oliveira
Banca: Fabiana Rizzi Bozzo
Doutor

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Terörde, Anja Isabel. "Variation in the use of intermittently open estuaries by birds : a study of four estuaries in the Eastern Cape, South Africa". Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/6209.

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Includes abstract.
Includes bibliographical references (leaves 87-99).
The main objective of this study was to describe the use of intermittently open estuaries (IOEs) along a section of the Eastern Cape coast by waterbirds, and the factors that influence avifaunal community composition in space and time. The study area consisted of four IOEs of varying sizes within a 40 km stretch of coastline in the warm temperate coastal biogeographical region of South Africa.

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