The Bushmans Estuary is one of the few permanently open estuaries in the Eastern Cape that is characterized by large intertidal salt marshes. Freshwater inflow to the estuary has decreased as a result of abstraction by more than 30 weirs and farm dams in the catchment. The mean annual run-off is naturally low (38 x 106 m3 y-1) and thus abstraction and reduction of freshwater inflow to the estuary is expected to cause a number of changes. The aims of this study were to determine the current health/status of the estuary based on the macrophytes and microalgae and identify monitoring indicators for the East London Department of Water Affairs, River Health Programme. Changes in the estuary over time were determined from available historical data which were compared with present data. This analysis showed that under normal average conditions freshwater inflow to the estuary is very low, less that 0.02 m3 s-1 most of the time. Under these conditions the estuary is in a homogenous marine state. Vertical and horizontal salinity gradients only form when high rainfall and run-off occurs (> 5 m3.s-1). Salinity gradients from 30.1 PSU at the mouth to 2.2 PSU in the upper reaches were measured in 2006 after a high flow event. However the estuary quickly reverted back to its homogenous condition within weeks after this flood. This study showed that freshwater inflow increased nutrient input to the estuary. Total oxidised nitrogen (TOxN) and soluble reactive phosphorus (SRP) concentrations were higher in August 2006, after the flood, than during the other low flow sampling sessions. TOxN decreased from a mean concentration of 21.6 μM in 2006 to 1.93 μM in February 2009. SRP decreased from 55.3 μM to 0.2 μM respectively. With the increased nutrient availability, the response in the estuary was an increase in phytoplankton biomass. After the 2006 floods the average water column chlorophyll-a was 9.0 μg l-1, while in the low freshwater inflow years it ranged from 2.1 to 4.8 μg l-1. The composition of the phytoplankton community was always dominated by flagellates and then diatoms, with higher cell numbers in the nutrient-enriched 2006 period. Although the water column nutrient data indicated that the estuary was oligotrophic, benthic microalgal biomass (11.9-16.1 μg.g-1) in the intertidal zone was comparable with nutrient rich estuaries. Benthic species indicative of polluted conditions were found (Nitzschia frustulum, Navicula gregaria, Navicula cryptotenelloides). These benthic species were found at the sites where wastewater / sewage seepage had occurred. Benthic diatom species also indicated freshwater inflow. During the high flow period in 2006 the dominant diatoms were fresh to brackish species that were strongly associated with the high concentrations of TOxN and SRP (Tryblionella constricta, Diploneis smithii, Hippodonta cf. gremainii, and Navicula species). During the freshwater limited period of 2008 and 2009 the benthic diatom species shifted to a group responding to the high salinity, ammonium and silicate concentrations. The species in this group were Nitzschia flexa, Navicula tenneloides, Diploneis elliptica, Amphora subacutiuscula and Nitzschia coarctata. Ordination results showed that the epiphytic diatom species responded to different environmental variables in the different years. Most of the species in 2008/2009 were associated with high salinity, temperature, dissolved oxygen, ammonium and silicate concentrations while the response was towards TOxN and SRP in 2006. The dominant species were Cocconeis placentula v euglyphyta in 2006; Nitzschia frustulum in 2008; and Synedra spp in 2009. The average biomass of the epiphytes was significantly lower in May 2008 than in both August 2006 and February 2009; 88.0 + 17.7 mg.m-2, 1.7 + 0.8 mg.m-2, and 61.8 + 14.4 mg.m-2 respectively. GIS mapping of past and present aerial photographs showed that submerged macrophyte (Zostera capensis) cover in 1966 and 1973 was less than that mapped for 2004. Salt marsh also increased its cover over time, from 86.9 ha in 1966 to 126 ha in 2004, colonizing what were bare sandy areas. Long-term monitoring of the health of the Bushmans Estuary should focus on salinity (as an indicator of inflow or deprivation of freshwater), benthic diatom identification and macrophyte distribution and composition (for the detection of pollution input), and bathymetric surveys (for shallowing of the estuary due to sedimentation).

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.

The Sundays Estuary is permanently open to the sea and has been described as channel-like along its entire length with a narrow intertidal area (mostly less than 5 - 6 m in width). The estuary experiences regular freshwater inflow with large supplies of nutrients, derived from the Orange River transfer scheme and agricultural return flow. In particular, nitrate concentrations are high as a result of fertilisers used in the Sundays River catchment area. The objectives of this study were to measure microalgal biomass and community composition and relate to flow, water quality and other environmental variables. Surveys in August 2006, March 2007, February, June and August 2008 showed that salinity less than 10 percent mostly occurred from 12.5 km from the mouth and this was also where the highest water column chlorophyll a (>20 μg l-1) was found. Different groups of microalgae formed phytoplankton blooms for the different sampling sessions, which were correlated with high chlorophyll a. These included blooms of green algae (August 2006), flagellates (March 2007), dinoflagellates (June 2008) and diatom species (February and August 2008). The dominant diatom (Cyclotella atomus) indicated nutrient-rich conditions. Green algae and diatoms were associated with low salinity water in the upper reaches of the estuary. Flagellates were dominant throughout the estuary particularly when nutrients were low, whereas the dinoflagellate bloom in June 2008 was correlated with high ammonium and pH. Maximum benthic chlorophyll a was found at 12.5 km from the mouth in February, June and August 2008 and was correlated with high sediment organic and moisture content. Benthic diatoms were associated with high temperature whereas some species in June 2008 were associated with high ammonium concentrations. The middle reaches of the estuary characterise a zone of deposition rather than suspension which would favour benthic diatom colonization. Phytoplankton cells settling out on the sediments may account for the high benthic chlorophyll a because maximum water column chlorophyll a was also found in the REI zone (where salinity is less than 10 percent and where high biological activity occurs) in the Sundays Estuary.

Orientador: Sueli Yoshinaga Pereira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-07T09:50:38Z (GMT). No. of bitstreams: 1 BatistaFilho_JobJesus_M.pdf: 4294081 bytes, checksum: 28f487525ec460febd41ef1f05e36218 (MD5) Previous issue date: 2006 / 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

The Greenland and Antarctic ice sheets are losing mass and contributing to global sea-level rise. Ice shelves, floating ice attached to the margins of the ice sheets, modulate sea-level rise by restraining ice-sheet flow out towards the oceans, but are sensitive to surface melting. The formation of surface meltwater lakes on ice shelves can trigger rapid ice-shelf collapse. However, surface meltwater also flows atop ice shelves through rivers. The impact of rivers on ice-shelf stability is unknown. Previous studies of ice-shelf hydrology hypothesize that rivers mitigate the damage-potential of lakes by removing surface water off of the ice shelf, but also suggest that rivers enhance ice-shelf fracturing by incising into areas of already thin ice. This dissertation is focused on exploring the role of rivers on ice-shelf stability using remote sensing datasets, conceptual models, and Augmented Reality (AR). Focusing on ice shelves in Greenland, I present the discovery of a new ice-shelf surface hydrology feature, an ice-shelf estuary, and demonstrate its potential to weaken ice shelves. I fully document this new process on the Petermann Ice Shelf, where flow reverses at the mouth of the Petermann Estuary. This study marks the first observation of ocean water atop an ice shelf. I also document the initiation and growth of fracturing along the estuary channel, and a history of rectilinear calving events, where icebergs calve along longitudinal rivers. Based on this analysis of the Petermann Estuary, I propose a new mechanism for damaging ice shelves: estuarine weakening. I present evidence that this process also occurs on the Ryder Ice Shelf in northwest Greenland. My analysis demonstrates that the role of rivers on ice-shelf stability depends on how the river mouth evolves. If ice-shelf waterfalls at the river mouth incise to sea level and form estuaries, flow reversal will modulate water export off the shelf and maintain the damage-potential of lakes, and estuarine weakening may lead to a new mode of ice-shelf calving. By analyzing the three-dimensional (3D) structure of the Petermann and Ryder Ice Shelves and Estuaries with remote sensing and radar data, I find that basal channels are an important driver of estuary development as they dictate the linearity of surface rivers. Determining the role that basal channels play in estuary formation requires accurate and appropriate data visualization tools. I develop AR applications to visualize radar data on ice shelves, towards enabling more intuitive and sophisticated interpretation of the ice-shelf structure in 3D. Through simple conceptual modeling, I suggest that although basal channels precondition ice-shelf estuary formation, estuary formation is strongly controlled by river incision. Finally, I present a model of ice-shelf estuary formation as a function of surface and basal melting. Using this conceptual model, I predict that ice-shelf estuaries could form in Antarctica in the near future. Surface melting in Antarctica is predicted to increase in under half a century. Estuary formation in Antarctica will be accelerated by lengthening of the melt season, and estuaries may form far from the calving front if rivers intersect upstream rifts. I show that ice-shelf estuaries could evolve from ice-shelf rivers in a warming Antarctica, introducing new ice-shelf weakening mechanisms. This increases the urgency to understand and include ice-shelf estuarine processes in ice-sheet models.

The Hudson River estuary (HRE) is a well monitored aquatic resource and much secondary data exist for this system. We developed two objectives based on accessible HRE aquatic data. The first objective was to determine if changes in HRE fish community over the time period (1974 to 2005) years are correlated to local and regional climate. We addressed this objective by employing a multivariate statistical approach. We confirmed that the HRE fish community structure has changed over the time period (1974 to 2005). These changes are correlated with local hydrology (freshwater flow and water temperature) and regional climate (Atlantic Multidecadal Oscillation or AMO and North Atlantic Oscillation or NAO). We found that abundances of striped bass larval stages are positively correlated with high freshwater flows and juvenile shad abundances are negatively correlated with the AMO or warmer sea surface temperatures (SST). This finding suggests that climate-related variability affects HRE juvenile shad abundances and current management strategies for this declining species should include the implications of climate change. The second objective was to examine whether factors such as sediment type, water characteristics and distance to nearest submerged aquatic vegetation (SAV) beds affect the occurrence or presence/absence of juvenile American shad (Alosa sapidissima) and juvenile striped bass (Morone saxatilis) in the HRE during the fall. We addressed this objective by applying geostatistics and general linear mixed effects models. We found the probability of presence for both species were commonly driven by spatial dependence or river mile, Julian day and salinity. Our results include maps depicting probability of occurrence (or presence) for both species throughout the HRE. We found the highest predicted probabilities of juvenile American shad presence are found in the Upper HRE. Conversely, highest predicted probabilities of juvenile striped bass presence are found in the Lower HRE. Habitat partitioning between these two species is present during the fall in this system but the mechanism is unclear. Future studies could address a possible predator-prey or competitive relationship between juvenile American shad and juvenile striped bass.

The Gulf Coast Region (GCR) of the United States holds immense ecological and cultural value. However, constant environmental changes, from sea-level rise and hurricanes to the Deepwater Horizon oil spill in 2010, threaten many of the values that define the region. Additionally, recent financial settlements from civil and criminal penalties of the Deepwater Horizon oil spill have created an unprecedented opportunity to fund conservation throughout the region. With such a large area of interest (over 700,000 km2) and so many conservation priorities throughout the GCR, there is a great need to strategize which lands are most efficacious for conservation to optimize the protection of ecological and socioeconomic values. Given the importance of ecologically sound data to informing conservation planning, I directed my dissertation to develop gulf-wide datasets to be used in a geospatial tool to support land conservation actions in the GCR. My dissertation addresses three fundamental objectives: 1) assessing how landscapes are associated with estuarine biotic health; 2) mapping hydrologic response to changes in land-use; and, 3) creating indices of land conservation value with regards to modeled associations (from objective 1) with estuarine biotic health. For objective 1, I constructed three hierarchical models across 33 GCR estuaries and their associated watersheds. I estimated the expected number of fish and shrimp species observed in a trawl sample based on temperature, salinity, and runoff volume per catchment area across six different land-use/land-cover (LULC) classes. These models can provide a quantitative basis for assigning offsite values to lands for conservation potential within the GCR. For objective 2, I assessed associations of different LULC classes with hydrologic changes, measured by peak flow (cfs), from 1996-2016 within each GCR watershed, which can be valuable to conservation planning that seeks to focus on preserving or restoring more typical flow regimes. For my 3rd objective, I developed an index of conservation value which incorporates relationships among LULC, hydrologic connectivity, and estuarine biotic health for lands within the GCR. These elements will help address lesser understood land conservation needs in the GCR to better enable conservation planners to protect the values of this region in the face of inevitable change.

No description available.

Thesis (Ph.D.)--Mississippi State University. Department of Civil and Environmental Engineering. / Title from title screen. Includes bibliographical references.

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