O complexo estuarino-lagunar de Cananéia-Iguape vem sofrendo diversos impactos antrópicos desde à abertura do canal artificial Valo Grande, que alterou significativamente o setor Norte do sistema com o aumento da influência fluvial. O assoreamento da região, vem sendo um problema recorrente, impactando a pesca, o turismo e a navegação. Este trabalho visa entender a dispersão do aporte terrígeno na região a partir da modelagem numérica, com dados atualizados, para melhor reprodução da simulação no estuário. Os resultados do modelo mostraram altas concentrações dos componentes biogeoquímicos no setor Norte do sistema e baixa influência da maré, ocasionando alta retenção destes elementos na região. O setor Sul apresentou baixa influência do rio e alta influência marinha, com valores de silicato e fosfato dissolvidos e matéria inorgânica em suspensão dentro do esperado para um sistema estuarino preservado. O modelo apresentou um bom comportamento para a região, com bons resultados hidrodinâmicos e de qualidade da água. Ressalta-se a importância de um contínuo monitoramento da região e o uso de modelo para acompanhar o desenvolvimento geomorfológico e as alterações biogeoquímicas do estuário para auxiliar em medidas preventivas com o intuito de minimizar o impacto antrópico no sistema. / The estuarine-lagoon complex of Cananéia-Iguape has suffered several anthropic impacts since the opening of the Valo Grande artificial channel, which significantly altered the northern sector of the system with the increase of fluvial influence. The silting up of the region has been a recurrent problem, impacting fishing, tourism and navigation. This work aims to understand the dispersion of the terrigenous contribution in the region with numerical modeling and updated data, for better reproduction of the simulation in the estuary. The results of the model showed high concentrations of the biogeochemical components in the northern sector of the system and low tidal influence, causing high retention of these elements in the region. The southern sector showed low river influence and high marine influence, with expected values of dissolved silica and phosphate and inorganic suspended matter for a preserved estuarine system. The model showed a good behavior for the region, with good hydrodynamic and water quality results. It is emphasized the importance of continuous monitoring of the region and the use of a model to monitoring the geomorphological development and the biogeochemical alterations of the estuary to assist in preventive measures with the intention of minimizing the anthropic impact in the system.

The bioavailability of iron is limited by the solubility of Fe(III) at circumneutral pH. In the High Nutrient-Low Chlorophyll (HNLC) zones of the ocean, the natural or anthropogenic addition of iron stimulates primary productivity and consumes carbon dioxide. As a result, iron fertilization has been proposed to mitigate anthropogenic carbon emissions and lower global temperatures. The natural sources of iron to the ocean are not fully constrained and include eolian depositions as well as inputs from continental shelf sediments, rivers, hydrothermal vents, and icebergs. Regardless of their source, the effectiveness of iron additions in promoting carbon fixation depends on the presence of organic ligands either natural or produced by microorganisms that stabilize or solubilize Fe(III) at neutral pH. For example, siderophores are well known to be expressed extracellularly by prokaryotes in the photic zones of the oceans to increase the bioavailability of iron. In this dissertation, the production of iron nanoparticles is demonstrated in vent fluids from the 90 North hydrothermal system. These iron nanoparticles may either catalyze the oxidation of sulfide to thiosulfate and produce a potential electron acceptor for microbial respiration or provide a source of iron that stimulates primary production at great distances from the hydrothermal vents. In addition, dissolved iron under the form of soluble organic-Fe(III) complexes is demonstrated to constitute a significant source of iron in estuarine sediments that receive large amounts of particulate iron from flocculation and precipitation at the salinity transition of this estuary. A novel competitive ligand equilibration absorptive cathodic stripping voltammetry (CLE-ACSV) technique reveals that the speciation of iron changes from largely colloidal or particulate in the upper estuary to truly dissolved organic-Fe(III) in the lower estuary. It is also demonstrated that organic-Fe(III) complexes are produced far below the sediment-water interface, suggesting that dissimilatory iron-reducing bacteria may play an important role in their production. These complexes then diffuse across the sediment-water interface and provide a significant source of iron to the continental shelf. The mechanism of reduction of iron oxides by iron-reducing bacteria is not fully understood and presents a unique physiological problem for the organism, as the terminal reductase has to transfer electrons to a solid electron acceptor. In this dissertation, it is demonstrated for the first time using random mutagenesis that the respiration of solid Fe(III) oxides by Shewanella oneidensis, a model iron-reducing prokaryote, first proceeds through a non-reductive dissolution step involving organic ligands that are released extracellularly by the cells. These soluble complexes are then reduced by the organism to produce Fe(II) and recycle the ligand for additional solubilization. Incubations with deletion mutants of the proteins involved in the respiration of Fe(III) revealed that the type-II secretion system, which translocates proteins on the outer membrane of gram-negative bacteria, is involved in the production of organic-Fe(III) complexes by secreting an endogenous iron-solubilizing ligand or a protein involved in the biosynthesis of this ligand on the outer membrane. In addition, periplasmic decaheme cytochromes produced by Shewanella appear to be involved in the mechanism of production of the endogenous organic ligand either directly or through a sensing mechanism that controls its production. In turn, two decaheme cytochromes positioned on the outer-membrane and hypothesized to be involved in the electron transfer to the mineral surface do not appear to be involved in the solubilization mechanism, suggesting either that the cells regulate the ligand production via periplasmic sensing systems or that these cytochromes are not involved in the solubilization mechanism. Altogether this research shows the production of organic-Fe(III) complexes in sediments generates a significant flux of dissolved iron to support primary production in continental shelf waters and that these complexes may be partly produced by iron-reducing bacteria. Indeed, experiments with a model organism demonstrate dissimilatory iron reducing bacteria produce endogenous organic ligands with high iron-binding constants to non-reductively solubilize iron oxides during the anaerobic respiration of iron oxides. The organic ligand is apparently recycled several times to minimize the energy cost associated with its biosynthesis. These findings demonstrate that the solubilization of iron oxides by organic ligands may be an important, yet underappreciated process in aquatic systems.

Coastal systems like lagoons and estuaries are faced with severe human developmental endeavours. In South Africa, more than 30% of the population lives along the 3000 kilometer coastline. The Durban bay is no exception especially with the existing Durban harbour taking up the natural expanse of the bay. The bay is burdened with a diversity of anthropogenic endeavours, from port operations to industrial activities, to storm water drainage outlets, through to various recreational ventures. These activities have over the years caused a reduction of the bay‘s mangrove forest, reduced the population of some biota and caused extinction of some indigenous species. Five areas were selected based on the specific activities and infrastructure that occurred there. Samples of water from these pre-selected sites were collected routinely and analysed for their water quality status. The overall water quality within the bay compared with the DWAF water quality guidelines for South Africa was identified as below stipulated standards. The dissolved oxygen contents as well as nutrients in the form of nitrogen content in its assorted forms are some of the most affected water quality indicators. The majority of the sub standard water quality levels, indicators which are critical to the proper functioning, growth and reproduction of biota within the ecosystems of the bay obtained could be linked directly or indirectly to the activities within the area of sampling. The resultant chemical and physical conditions in water quality created as a result of the ongoing activities within the bay are not suitable for proper feeding, growth and reproduction of ecosystems. This has caused many species within the bay to migrate or adapt to the adverse conditions and such situations are likely to worsen if stringent measures are not taken in the near future. It appears that the some species are exhibiting some degree of resilience and are at the moment surviving the relatively harsh conditions within the bay. The long term effect of the ever expanding anthropogenic disturbances on the ecosystems are unpredictable and it is therefore imperative that more stringent environmental management plans, programs and policies, legally binding, are formulated to serve as a check on all who benefit from the bay‘s resources. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.

The zooplankton communities of the Mdloti and Mhlanga estuaries were studied over a 13-month period (March 2002-March 2003). Monthly daytime samples were collected from both estuaries at the lower, middle and upper reaches using a WP-2 net and a hyperbenthic sled. Throughout the study period, the Mdloti Estuary experienced nine breachings, while the Mhlanga experienced 16 such events. Significant differences in zooplankton abundance were observed between the two estuaries (F I, 73 = 5.2; P<0.05), with the Mdloti consistently exhibiting higher values than the Mhlanga. No significant differences were, however, observed in zooplankton biomass between the two estuaries (U = 634; P>0.05). At the Mdloti, zooplankton abundance ranged from 20 ind.m-3 to 5.4 x 106 ind.m-3 , while at the Mhlanga this ranged from 76 ind.m-3 to 2.0 x 105 ind.m-3 • Zooplankton biomass ranged from 0.08 mg.m-3 (OW) to 2010 mg.m-3 (OW) at the Mdloti, and from 0.18 mg.m-3 (OW) to 1210 mg.m-3 (OW) at the Mhlanga. A one-way ANOV A revealed significant differences in zooplankton abundance between the open and the closed phase, both at the Mdloti (FI, 30 = 59; P<0.05) 'and the Mhlanga (FI, 38 = 7.3; P<0.05), with the closed phase exhibiting consistently higher values than the open. Similarly, biomass was significantly higher during the closed than the open phase, both at the Mdloti (U= 16.5; P<O.OI) and the Mhlanga (U= 88, P<O.O 1). This pattern may be attributed to the stability achieved by these systems during periods of mouth closure, when the estuaries exhibit less freshwater input and a restricted exchange of water with the sea. At the Mdloti, zooplankton biomass (OW) was positively correlated to both phytoplankton (r= 0.36) and microphytobenthos biomass (r = 0.41). At the Mhlanga, zooplankton biomass (OW) was only positively correlated to phytoplankton biomass (r = 0.45) The most abundant taxa at the Mdloti during the open phase were Pseudodiaptomus hessei and copepod nauplii, each contributing 38% and 32% of the total stock, respectively. During the closed phase, however, rotifers were by far the dominant taxon, contributing 82% of the total zooplankton abundance. These were followed by cope pod nauplii with 16%. At the Mhlanga, the most abundant groups during the open phase were again the copepod nauplii (89%) and P. hessei (7 %), while the closed phase was dominated mainly by caridean larvae (39%) and copepod nauplii (26%). The dominance of P. hessei during the open phase of both estuaries may be attributed to the pioneering nature of this species. The dominance of rotifers at the Mdloti during the closed phase may have been due to the freshwater conditions that prevailed in this estuary as a result of prolonged mouth closure. The concentration of copepod nauplii increased dramatically 2-4 weeks after major rain events, possibly due to the hatching of dormant eggs in response to freshwater pulses. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.

<p>Estuaries interfacing with the land, atmosphere and open oceans can be influenced in a variety of ways by anthropogenic activities. Centuries of overexploitation, habitat transformation, and pollution have degraded estuarine ecological health. Key concerns of public and environmental managers of estuaries include water quality, particularly the enrichment of nutrients, increased chlorophyll a concentrations, increased hypoxia/anoxia, and increased Harmful Algal Blooms (HABs). One reason for the increased nitrogen loading over the past two decades is the proliferation of concentrated animal feeding operations (CAFOs) in coastal areas. This dissertation documents a study of estuarine eutrophication modeling, including modeling of major source of nitrogen in the watershed, the use of the Bayesian Networks (BNs) for modeling eutrophication dynamics in an estuary, a documentation of potential problems of using BNs, and a continuous BN model for addressing these problems.</p><p>Environmental models have emerged as great tools to transform data into useful information for managers and policy makers. Environmental models contain uncertainty due to natural ecosystems variability, current knowledge of environmental processes, modeling structure, computational restrictions, and problems with data/observations due to measurement error or missingness. Many methodologies capable of quantifying uncertainty have been developed in the scientic literature. Examples of such methods are BNs, which utilize conditional probability tables to describe the relationships among variables. This doctoral dissertation demonstrates how BNs, as probabilistic models, can be used to model eutrophication in estuarine ecosystems and to explore the effects of plausible future climatic and nutrient pollution management scenarios on water quality indicators. The results show interaction among various predictors and their impact on ecosystem health. The synergistic eftects between nutrient concentrations and climate variability caution future management actions.</p><p>BNs have several distinct strengths such as the ability to update knowledge based on Bayes' theorem, modularity, accommodation of various knowledge sources and data types, suitability to both data-rich and data-poor systems, and incorporation of uncertainty. Further, BNs' graphical representation facilitates communicating models and results with environmental managers and decision-makers. However, BNs have certain drawbacks as well. For example, they can only handle continuous variables under severe restrictions (1- Each continuous variable be assigned a (linear) conditional Normal distribution; 2- No discrete variable have continuous parents). The solution, thus far, to address this constraint has been discretizing variables. I designed an experiment to evaluate and compare the impact of common discretization methods on BNs. The results indicate that the choice of discretization method severely impacts the model results; however, I was unable to provide any criteria to select an optimal discretization method.</p><p>Finally, I propose a continuous variable Bayesian Network methodology and demonstrate its application for water quality modeling in estuarine ecosystems. The proposed method retains advantageous characteristics of BNs, while it avoids the drawbacks of discretization by specifying the relationships among the nodes using statistical and conditional probability models. The Bayesian nature of the proposed model enables prompt investigation of observed patterns, as new conditions unfold. The network structure presents the underlying ecological ecosystem processes and provides a basis for science communication. I demonstrate model development and temporal updating using the New River Estuary, NC data set and spatial updating using the Neuse River Estuary, NC data set.</p> / Dissertation

St. Lucia estuarine lake system has a history of episodic droughts and floods leading to a high variability in physico-chemical characteristics which may influence the community structure of nano- and microplankton that are the main primary energy synthesisers in aquatic systems. Originally, the St. Lucia estuary and the Mfolozi River shared the same mouth with the Mfolozi River acting as the main source of fresh water to the system and as stabiliser of the common inlet. Due to prolonged mouth closure from 2001-2012 and high evaporation rates, severe extended droughts and high salinities were experienced in 2001-2012.This project aimed to characterise community composition and biomass of nano-and microplankton (autotrophic and heterotrophic) under the varying and extreme physico-chemical conditions in order to characterize the energy basis of the planktonic food web in St. Lucia. Its main objectives were to compare and add onto Johnson’s (1977) list of phytoplankton taxa in the system, to estimate the biomass (carbon) of nano- and microplankton from cell counts and biovolume measurements, and lastly to understand and establish trends in the change in community structure of these organisms with the varying physico-chemical characteristics. Nano- and microplankton samples were collected monthly from October 2010 to September 2011 at three different sites: Lister’s Point, Charters Creek and the mouth representing the lakes and estuary Channel. Chlorophyll a and physico-chemical parameters were also measured in situ during collection. In the lab, samples were settled using the Utermöhl method and species were identified to at least genus level, counted and cell measurements taken under an inverted microscope for biovolume calculations and biomass thereof. Abundance in cells per liter and biomass (carbon) in pg/L was then analyzed from the counts. The nano-and microplankton groups recorded in the system were cyanobacteria, chlorophytes, cryptophytes, dinoflagellates, ciliates and diatoms. Seventy eight phytoplankton taxa were identified composed of 56 diatoms, eight green algae, one cryptophyte, seven cyanobacteria and six dinoflagellate taxa. Nineteen ciliate taxa were also found. Only 12 of the diatom taxa identified in this study were listed by Johnson (1977), none of the taxa in the other phytoplankton groups was listed by Johnson (1977). The Johnson (1977) study conducted in the system from 1975-1977 listed the phytoplankton taxa occurring at that time. There was no significant difference in the community composition, biovolume and biomass between seasons hence no seasonal trend however, there were significant differences in the nano- and microplankton community composition, biovolume and biomass at the three different sites of the system. Cyanobacteria were the main taxa in the northern embayments dominating in abundance, biovolume and biomass (biological variables), green algae and cryptophytes dominated in abundance, biovolume and biomass in the Channels while in South Lake, green algae dominated in abundance but diatoms dominated in biovolume and biomass. Ciliate biological variables were higher in the northern regions than in the other parts of the estuary. The absence or limited grazing pressure of ciliate predators in the northern region due to their inability to cope with the extreme salinities compared to the other parts of the system explains why the northern embayments had the highest abundance, biovolume and biomass of ciliates. Ciliates and heterotrophic dinoflagellates were the heterotrophs in this study. Autotrophic:heterotrophic biomass ratio was lowest in the northern regions as heterotrophs had a higher biomass there. This ratio was higher in the South Lake and the Channel. The lack of stratification and generally high turbidity in the system made the system unfavourable for dinoflagellate growth. The higher presence of ciliate predators in the South Lake and Channel probably accounts for the low heterotrophic biomass hence high autotrophic:heterotrophic biomass ratio in South Lake and the Channel. Nutrients were not limiting during this study and salinity was the main physico-chemical characteristic accounting for the differences in nano- and microplankton biological variables. The Cyanothece bloom in the northern region was primarily due to high salinities (>150) which also indicated unfavourable conditions for other plankton types. The high diatom biomass in the southern lake was due to low salinities (<28) which favoured their growth, whereas chlorophytes and cryptophytes dominated in the Channel mainly due to low turbidity (median of 11.4NTU) and fresh water input from the Mfolozi lowering salinities (<5). The South Lake and Channel thus had the highest available energy for higher trophic level organism since 1) diatoms and green algae are the most favoured food source for phytoplankton grazers while the cyanobacteria though most abundant are the least favoured food source leaving the northern lake with smaller energy source for higher trophic level organisms and 2) The low autotrophic:heterotrophic biomass ratio in the northern region leaves the region with a lower net carbon biomass than the other parts of the system with a higher autotrophic: heterotrophic biomass. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.

Phosphorus is an essential element since it controls primary productivity in aquatic ecosystems and its excess can lead to eutrophication in receiving systems. The aim of this project was to determine phosphorus distribution in biotic and abiotic nutrient pools of two KwaZulu-Natal estuaries. Samples of dissolved inorganic phosphorus (DIP), particulate phosphorus (PP), phytoplankton, microphytobenthos, zooplankton, macrozoobenthos and sediment were collected in the temporarily open/closed Mpenjati (MP) and permanently open Mlalazi Estuary (ML) during May (ML), September (MP) and November (ML+MP) using standard methods. Chlorophyll a concentrations as well as species richness, abundance and biomass of zooplankton and macrozoobenthos were analysed. Living and non living nutrient pools were analysed for phosphorus and were compared between stations, sampling sessions, estuaries and taxa. Zooplankton abundance and biomass in the Mlalazi Estuary was higher during May than November. In the Mpenjati Estuary highest zooplankton abundance and biomass was recorded during September than November. No significant differences were apparent in abundance (p = 0.217) and biomass (p = 0.974) of zooplankton between the two estuaries. Macrozoobenthos abundance and biomass in the Mlalazi Estuary was higher during May than November. In the Mpenjati Estuary macrozoobenthos abundance and biomass was higher during November than September. Significant differences in abundance (p = 0.003) and biomass (p = 0.020) were apparent between the estuaries. Sediment to a depth of 10 cm comprised the highest phosphorus biomass than any other nutrient pool in both Mlalazi (4871.1 mgP·m⁻² ± 5888.9 SD) and Mpenjati (2578.6 mgP·m⁻² ± 1828.0 SD) estuaries followed by DIP (120.5 mgP·m⁻² ± 177.7 SD and 5.9 mgP·m⁻² ± 6.1 SD respectively). In both estuaries, the lowest phosphorus biomass was contained in zooplankton with both estuaries containing zooplankton P biomass of 0.001 mgP·m⁻² ± 0.002 SD. Particulate phosphorus and DIP concentrations were higher in the upper reaches in both estuaries indicating that rivers were the main sources of this nutrient in these systems. The Mlalazi Estuary had higher nutrient levels than the Mpenjati Estuary. Such elevated nutrients can be enhanced by the continuous river flow into the permanently open estuary. In both estuaries, no significant differences were apparent in zooplankton and macrozoobenthos P content between different taxa. / M.Sc. University of KwaZulu-Natal, Durban 2013.

Thesis (M.S.)--Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

xviii, 160 p. : ill. (some col.) / Salt marshes are intertidal communities dominated by halophytic vascular plants that are subjected periodically to tidal inundation. These species have developed various adaptations to this stress, including tolerances of fluctuating salinity, extended periods of inundation and intervals of anoxic conditions. The marshes are divided into zones of different plant communities based on species' tolerances of ambient estuarine conditions. Abiotic stresses change along the estuarine salinity gradient (marine to riverine), potentially altering development and composition of plant communities. Abiotic gradients associated with tides are not the only factors that contribute to development of plant community composition in salt marshes. Both negative (competition) and positive (facilitation) biological interactions are also important. Factors that influence community structure in salt marshes, particularly on the eastern North American seaboard, have been well studied. In contrast, salt marshes along the Oregon coast are smaller and more discrete and have received comparatively little attention. The community structure and seed bank composition of six marshes along an estuarine salinity gradient were evaluated. Four major community types dominated marshes that varied in the salinity of inundating tidal waters. Community types were relatively consistent throughout the estuary despite the distances between the marshes. Unlike the emergent plant communities, marsh seed bank composition was more similar within a marsh than within a community type. The low and high marsh community types were separated by a distinct boundary in the marine marshes. Although abiotic factors influence the physical separation of communities, competitive interactions commonly determine the upper limit of a species. In Metcalf marsh, however, the upper boundary for two dominant low marsh species was not determined by competition with the high marsh dominant species. Positive biotic interactions between seedlings and existing vegetation in a community are important factors in determining species distributions, particularly in stressful estuarine environments. In salt marshes, where abiotic stress can be harsh, presence of existing vegetation can ameliorate these conditions and enhance germination and seedling establishment. However, interaction between seedlings and the emergent marsh community was highly competitive, though germination of one species was enhanced in the presence of existing vegetation. This dissertation includes un-published co-authored material. / Committee in charge: Dr. Scott Bridgham, Chairperson; Dr. Richard Emlet, Advisor; Dr. Steven Rumrill, Member; Dr. Alan Shanks, Member; Dr. Gregory Retallack Outside Member

Submitted by Renato Miani Goncalves null (renatomiani@gmail.com) on 2016-08-05T18:39:41Z No. of bitstreams: 1 Tese - Renato Goncalves.pdf: 4535061 bytes, checksum: ea8e64f761cc44656f8a8018ef7c2d85 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-08-10T16:44:41Z (GMT) No. of bitstreams: 1 goncalves_rm_dr_araiq.pdf: 4535061 bytes, checksum: ea8e64f761cc44656f8a8018ef7c2d85 (MD5) / Made available in DSpace on 2016-08-10T16:44:41Z (GMT). No. of bitstreams: 1 goncalves_rm_dr_araiq.pdf: 4535061 bytes, checksum: ea8e64f761cc44656f8a8018ef7c2d85 (MD5) Previous issue date: 2016-07-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O sudeste brasileiro é a região mais populosa do país, estando nele o estuário de Santos-São Vicente, com aproximadamente 1,5 milhões de habitantes. Localizado nesse complexo estuarino, está o Porto marítimo mais movimentado da América Latina e um dos mais importantes pólos petroquímicos do país. Nessa região o tratamento de esgoto sanitário é praticamente inexistente (cobrindo aproximadamente 20% de toda população), não havendo estudos sobre a ocorrência ambiental e a dinâmica de estrógenos ou outros alteradores endócrinos no local. Por outro lado, frequentemente os estudos ambientais existentes sobre a ocorrência de contaminantes, negligenciam a confiabilidade analítica. Frente à esse cenário, o presente estudo apresenta a determinação de estrógenos (17α–etinilestradiol (EE2), 17β-estradiol (E2) e estriol (E3)) em água do mar com alta confiabilidade, utilizando método baseado em extração em fase sólida (SPE) e análise por HPLC-FLD, com o uso de ferramentas estatísticas para a modelagem da curva analítica, avaliação do efeito matriz e estudo de conservação dos cartuchos SPE após a eluição da amostra. O processo de validação analítica mostrou valores adequados de recuperação (76-94%, para diferentes concentrações de EE2, E2 e E3), precisão (coeficiente de variação menor que 20%) e seletividade. Os limites de deteção do método para o EE2, E2 e E3 foram respectivamente de 9,7, 2,3 e 4,3 ng L-1. Cinco curvas analíticas para cada composto foram utilizadas para avaliar o efeito matriz, sendo as soluções padrões preparadas em solvente (acetonitrila), água marinha artificial (S=30) e agua marinha, sendo para essas últimas, os padrões adicionados hora antes da extração, hora após a eluição da amostra no cartucho. Para o preparo de cada curva analítica foram utilizados seis concentrações diferentes dos padrões, sendo as curvas analíticas refeitas para cada amostragem realizada. O modelo teve por base a regressão linear, utilizando ajuste por mínimos quadrados, sendo o mesmo avaliado por análise de variância (ANOVA). Os resultados mostraram efeito matriz para todos os analitos. A conservação dos analitos nos cartuchos SPE foram avaliados para 6; 22; 29; 55 e 80 dias, e os resultados evidenciaram que não houve diferença significativa entre eles. Foram realizadas três amostragens no estuário de Santos-São Vicente, em março de 2014 (12 pontos amostrais de superfície), e fevereiro e junho de 2015 (com 15 pontos amostrais de superfície e 6 pontos amostrais de águas de fundo, na baía de Santos). Os valores de concentração para o estriol (mais frequentemente encontrado) variaram entre ND-354 ng L-1, para o 17β-estradiol de nd-18 ng L-1 enquanto o 17α–etinilestradiol não foi quantificado em nenhuma das amostras. Não foram observadas diferenças entre as amostragens nas diferentes estações do ano, sendo as maiores variações de concentrações observadas no âmbito de diferentes comportamentos de maré (sizígia e quadratura). No geral, os valores de concentrações encontrados para o estriol e estradiol podem acarretar riscos aos organismos aquáticos quando os mesmos são expostos à esses alteradores por longos períodos. / Southeast is the Brazilian most populated region. Santos-São Vicente estuary, located there, includes c.a. 1.5 million inhabitants, one of the most important Brazilian petrochemical sites and the bigger harbor from Latin America. In this region, the sewage treatment is almost inexistent (covers c.a. 20% of all population), nevertheless there are not studies about the occurrence and environmental dynamics of estrogens or others endocrine disruptors there. On the other hand, the analytical reliability in environmental studies have been frequently neglected. Thus, this work presents a reliability evaluation for estrogens (EE2, E2 and E3) determination in marine water, using a method based in solid phase extraction (SPE) and HPLC-FLD analysis, statistical tools were used to accomplish the calibration curve, storage time of SPE cartridges after sample elution and matrix effects. The analytical validation process showed adequate selectivity, recovery (76-94%, for different concentrations of EE2, E2 and E3) and precision (RSD below 20%). The method detection limit for EE2, E2 and E3 was 10, 2 and 4 ng L-1, respectively. Five analytical curves for each compound were used to evaluate the matrix effect wherein the standard solutions were prepared in solvent (acetonitrile, or on the SPE extract from artificial seawater (S=30) or in natural seawater). Additionally, for artificial and natural seawater, the standards were spiked to matrix before the SPE. All standard solution contained all the studied estrogens, at the same concentration, for each curve it was used six standards concentrations. Model fitting was done by linear regression models, using ANOVA to evaluate the fittings. The results showed matrix effects for all analytes, thus matrix-matched (natural seawater) analytical curves were used at the following method validation steps. SPE cartridges storage time (after sample loading) was studied for 6, 22, 29, 55 and 80 storage days, data demonstrated no significant differences for these storage times. Three sampling was made at Santos estuary, in march 2014, february 2015 and june 2015, with 15 samples collected each. Estriol (E3) concentrations ranging ND-354 ng L-1, estradiol (E2) ND-18 ng L-1 while 17α–ethynylestradiol (EE2) were not detectable in any samples (below method LOQ). Overall, estriol concentration are above no-observed-effect concentrations from long-term exposition, which can lead to risk for aquatic organisms.