Microplastics are widespread and abundant. Few studies have examined the diversity and abundance of microplastics in wild organisms. This study determined the microplastic quantity and types in the organic tissues of the eastern oyster Crassostrea virginica and Atlantic mud crab Panopeus herbstii from the Indian River Lagoon (IRL). This study also investigated whether location affected the microplastic abundance and variety. Organisms were collected from three sites across Mosquito Lagoon in the northern IRL. Oysters were frozen after collection. Crabs were placed in containers for 5 days before freezing. The soft organic tissue was chemically digested using hydrogen peroxide, filtered, and examined for microplastics. Water samples collected from each study site had an average of 23.1 microplastic pieces per liter and fibers were the most common type. There was a significant interaction for microplastic type and site for both oysters and crabs (p

Oyster reefs are important estuarine ecosystems that provide habitat to many species including threatened and endangered wading birds and commercially important fishes and crabs. Infaunal organisms (i.e. small, aquatic animals that burrow in the sediment) are also supported by oyster reef habitats. Infaunal organisms are critical to marine food webs and are consumed by many important species that inhabit coastal estuaries. However, over the past century 85% of shellfish reef habitats have been lost, making restoration of these areas vital. Due to their important role in coastal food webs, infauna is hypothesized to be a strong indicator of habitat productivity to document the transition from a dead to a restored and living intertidal oyster reef. Research was conducted in Mosquito Lagoon of the northern Indian River Lagoon system. Three replicate samples were collected from 12 intertidal oyster reefs (four dead, four live, four restored). Samples were collected one-week pre-restoration and one month and six months post-restoration. Infauna was counted and sorted into six taxonomic categories: polychaetes, amphipods, isopods, gastropods, bivalves, and decapods. Reef infaunal abundance increased following restoration: restored reefs became more similar to live reefs one month following restoration. Six months after restoration restored reefs were also significantly different than dead reefs. Live reefs consistently had high infaunal abundance and dead reefs consistently had low abundance, while restored reefs were intermediate. These data suggest restored reefs are more productive than their dead counterparts, with restoration showing a positive trajectory to impact numerous infaunal species and their associated food webs.

Vibrio choleraeis the etiological agent of the severe diarrheal disease-cholera and natural inhabitant of estuarine and coastal waters. The proximity of the Florida Indian River Lagoon (IRL) to areas affected by recent cholera outbreaks makes this estuary ideal to investigate the environmental dynamics and their potential role in V. cholerae's pathogen emergence. We identified two locations in the IRL, Feller's House UCF Field Station and Shepard Park, as our collection sites. We collected samples from three different fractions - water, plankton, and sediment - and recorded data for several water parameters such as pH, temperature, and, turbidity. In the laboratory, we enriched samples in alkaline peptone water and isolated V. choleraeusing widely used selective media Thiosulfate-Citrate Bile Salts-sucrose agar (TCBS) and CHROMagar Vibrio. From our study, we isolated 100 potential V. cholerae isolates, which were confirmed using biochemical tests such as oxidase and Kligler's Iron Agar. V. cholerae has allelic variations in the core genes such as ompU, which provide pre-adaptation to virulence. We investigated the allelic variations within ompU to characterize V. cholerae isolates. We elucidated the sequenced allele of ompU and built a neighboring-joining phylogeny tree to view the differentiation among vibrios. Our findings provide insight into the endemic population of V. cholerae in the Eastern Coast of Florida. Further studies include a screen for additional virulence genes and investigate the role of environmental dynamics on the distribution of V. cholerae and emergence as a human pathogen.

[pt] Estuários são corpos de água costeiros semi-fechados que servem como receptores finais de matéria orgânica. Os contaminantes emergentes correspondem, na maioria dos casos, a contaminantes não regulamentados, que podem ser candidatos a regulamentação futura, dependendo da pesquisa sobre seus efeitos potenciais para a saúde e dados de monitoramento relativos à sua ocorrência. Este é o caso dos produtos farmacêuticos e de cuidados pessoais (PPCPs) que possuem origem da contaminação antropogênica pela liberação contínua em águas residuárias ou diretamente no meio ambiente (via excreção humana e animal) sendo frequentemente persistentes e bioacumuláveis com difícil avaliação precisa do impacto no meio ambiente pela infinidade de fontes de entrada no ambiente. Este trabalho visa então o monitoramento de PPCPs na Lagoa de Piratininga que se localiza a leste da Baía de Guanabara, a qual passa por um acelerado processo de expansão residencial e comercial. Visando a otimização de tempo e custo, a extração das amostras foi definida com base em testes de diferentes metodologias, como a extração em fase sólida (SPE), etapa necessária para purificação do extrato. A identificação e quantificação foi realizada por cromatografia gasosa acoplada a espectrometria de massas em modo de monitoramento seletivo de íons (SIM) por aliar sensibilidade à elevada seletividade. Para análise por cromatografia gasosa ambos os métodos, porém, necessitam de prévia derivatização para formação de composto volátil. Para avaliar a qualidade do método, foi confirmada a linearidade das curvas analíticas pelo valor do coeficiente de determinação (R2) e pelo teste F na análise da variância (ANOVA) da regressão. A homocedasticidade dos dados foi confirmada pelo teste de Breusch e Pagan. O Limite de Detecção (LD) variou de 0,11 a 0,52 ng g-1. A repetibilidade, expressa através do desvio padrão relativo (DPR) apresentou valores inferiores a 30 por cento. A recuperação média dos analitos variou de 60 por cento a 118 por cento. O método validado foi aplicado para a análise do sedimento da Lagoa de Piratininga e obteve resultados que indicam uma presença significativa dos fármacos bisfenol A, beta-estradiol e ibuprofeno. / [en] Estuaries are defined as a semi-enclosed water that serve as final receptors of organic matter. Emerging contaminants correspond, in most cases, to unregulated contaminants, which may be candidates for future regulation depending on research on their potential health efects and monitoring data regarding their occurrence. This is the case of the pharmaceuticals and personal care products (PPCPs) which the contamination origin is above all anthropogenic and continuously released in wastewater or directly in the environment (via human and animal excretion). They are more often persistent and bioaccumulable and the accurate assessment of PPCPs impact on the environment is as difficult as there is a multitude of input sources in environment. This work then aims to monitor PPCPs in the Piratininga lagoon which is located east of the Guanabara Bay, that is undergoing an accelerated process of residential and commercial expansion. In order to optimize time and cost, the sample extraction was defined based on tests of different methodologies, such as Solid Phase Extraction (SPE), a necessary step for extract purification. Identification and quantification were performed by gas chromatography coupled with mass spectrometry in Selected Ion Monitoring mode (SIM), combining sensitivity with high selectivity. For gas chromatography analysis, both methods, however, require prior derivatization to form a volatile compound. To assess the quality of the method, the linearity of the analytical curves was confirmed by the coefficient of determination (R2) value and by the F-test in the analysis of variance (ANOVA) of the regression. The homoscedasticity of the data was confirmed by the Breusch-Pagan test. The Limit of Detection (LOD) ranged from 0.11 to 0.52 ng g-1. Repeatability, expressed through the relative standard deviation (RSD), showed values below 30 percent. The average recovery of the analytes ranged from 59,8 percent to 100,7 percent. The validated method was applied to analyze sediment from Piratininga Lagoon and obtained results indicating a significant presence of the pharmaceuticals bisphenol A, beta-estradiol, and ibuprofen.

The Indian River Lagoon (IRL) is an important estuary along Florida’s east coast. It is known for its ongoing water quality issues attributed to human activity in the watershed, which has resulted in extensive restoration and conservation efforts. This study researches the relationship between public perception and sentiment toward sustainable development initiatives and how they influence conservation and restoration in the Indian River Lagoon watershed. Twelve semi-structured interviews were conducted with IRL experts who work in the government, academia, nonprofit, or nongovernmental sectors to discuss public sentiment and engagement practices within the watershed. The responses were analyzed using a causal layered analysis, which highlighted social, political, and economic factors that influence public attitudes on various initiatives within the IRL ecosystem. Based on the findings, improved relationship building and diversity in IRL stakeholders are important to ensuring comprehensive community engagement with environmental stewardship and management.

Thừa Thiên Huế dispose d’une situation géographique stratégique, possédant des paysages somptueux, des villages artisanaux et d’une culture très riche avec deux patrimoines culturels mondiaux... Parmi les ressources naturelles potentielles de Hue, la lagune de Tam Giang - Cầu Hai (TG-CH), avec ses ressources précieuses, est une nouvelle destination touristique de cette province. À TG-CH, les activités touristiques sont apparues depuis 2010. Mais en réalité, le tourisme à la lagune de TG-CH ne montre pas vraiment qu’il est un outil efficace pour lutter contre la pauvreté pour la communauté lagunaire locale. Cette étude vise à un développement local durable en analysant plusieurs facteurs. Les analyses profondes sur les impacts touristiques, sur la participation communautaire dans le tourisme ont une relation directe avec la valeur perçue par la communauté locale sur le tourisme à TG-CH. Spécialement, une proposition initiale du « tourisme à la ville fantôme » dans la lagune de TG-CH montre une destination unique dans le monde entier que les responsables de Thừa Thiên Huế ne connaissent pas. Pour la première fois, la culture locale devient une clé importante pour comprendre, pour expliquer les pratiques des communautés locales. Cette recherche va être encore développée pour un développement local durable à TG-CH. / Thừa Thiên Huế inherites a strategic geographic position with many majestic landscapes, traditional villages and a diverse culture with two world cultural heritages. Among various potential natural resources of the place, Tam Giang – Cầu Hai Lagoon (TG-CH), with its precious resources, is an emerging tourist destination of the province. Althought tourism has established at TG-CH since 2010, it, in fact, has not shown as an effective tool for poverty alleviation. This research is aiming to a sustainable development of the area through analysing various factors. Analysises on the impacts of tourism and the involvement of local community in tourism have a very strong connection with the community perceived value in tourism. Specifically, a proposal for a model “tourism in the ghost town” at TG-CH would bring a unique aspect of a lost world which could not even be in the mind Thừa Thiên Huế authorities. For the first time, local culture becomes a significant key to understand and elaborate social changes. This research will continuously develop toward the sustainable development of TG-CH.

La thèse cherche à comprendre les significations socio-spatiales des dynamiques conflictuelles relatives à l'environnement en territoire lagunaire pour apprécier ses effets en termes de gouvernance environnementale. L'analyse porte sur les raisons et la genèse des oppositions d'acteurs à l'œuvre autour de la lagune de Bizerte (Tunisie) et de l’étang de Berre (Marseille). Mettre l’accent sur les conflits représente un enjeu pour la mise en place d’une gestion intégrée des zones humides. Ce sujet a été travaillé par d’autres chercheurs, cependant, il reste d’un intérêt majeur, d’une part, parce qu’il renforce la connaissance en la matière, et d’autre part, parce que le territoire étudié est original. La recherche pose plus particulièrement la question des éventuelles incidences que les conflits peuvent avoir sur les organisations et les institutions en place. L’action publique est-elle renouvelée suite à l’émergence ou à la régulation des conflits ? Ces questionnements se réfèrent à des enjeux de sociétés, actuels et majeurs, sur un territoire en mutation extrêmement rapide : la lagune de Bizerte, sur la rive Sud de la Méditerranée, dans un pays où le régime est en pleine transition. Cette recherche ouvre des perspectives dans l'étude du potentiel d'émergence de la démarche participative et de l'intégration sociale de la question environnementale sur des territoires littoraux, urbains ou ruraux. / The dissertation seeks to recognize the socio-spatial meanings of dynamic conflicts related to the environment in the lagoon and to assess its effects in terms of environmental governance as well. The analysis concentrates on the reasons and the genesis of the actors’ oppositions at work around the lagoon of Bizerte (Tunisia) and the pond of Berre (Marseille). Putting the light on these conflicts represents an issue for the integrated wetland management. This topic has been tackled on by other researchers. However, it remains a major interest due to the knowledge and the originality of the territory. Particularly, the thesis raises the question of the potential impacts that conflicts can have on organizations and institutions in place. In fact, is it possible that public action will be renewed to follow the emergence or conflicts regulation? This question is tied to the challenges of the current and major companies and to an extreme rapidity of territory changing: Bizerte’s lagoon is situated on the southern shore of the Mediterranean and in a country where the regime is in continuous transition. This research covers the ground to study the potential emergence of the participative approach and the social integration of environmental issues in coastal, urban and rural territory.

<p>During pulp and papermaking process a huge amount of water is used. The wastewater contains a large amount of pollutants and has to be treated before it reaches the recipient. In March 2004 a new bleaching plant was started up at SCA Graphic Sundsvall AB, Ortviken’s paper mill using peroxide. The production of bleached thermo mechanical pulp and thus the load to the wastewater plant increased. During bleaching substances dissolve from the pulp and the amount of COD in the wastewater increase. To keep the efficiency of chemical and biological oxygen demand (COD, BOD) removal, the aerated lagoon is supplied by liquid oxygen. In November the same year a new pre-step including a pre-aeration, carrier and selector step was added to the existing wastewater plant. The COD-loading to the lagoon decreased and the supply of liquid oxygen was reduced.</p><p>This master thesis has been carried out at SCA Graphic Research AB, Sundsvall. The aim was to chemically characterize the wastewater with focus on the composition of carbohydrates, lignin and extractives and its influence on the biodegradability. Measurements have been carried out on total samples, suspended solids, colloidal and dissolved substances using GF/A and ultra filtration. Measurements were performed on process water from the bleaching plant and on water during the wastewater treatment process. The results show that the chemical composition of dissolved substances has a larger impact on the biodegradability than the total amount of COD. A large amount of lignin will make the wastewater harder to degrade. Suspended solids have lower biodegradability compared to the dissolved fraction. Analyzes of suspended material from the bleaching plant show a relative composition of around 41 % lignin. Analyzes done before on the dissolved fraction show a composition of 29 %. It seems that a larger amount of lignin is represented in suspended solids compared to the dissolved fraction. This can explain the low biodegradability, combined with the theory that the suspended solids are less accessible for the microorganisms. To reduce the outgoing COD the incoming flow of dissolved lignin and suspended solids to the active sludge plant has to decrease. COD in the outgoing wastewater to the recipient consists of around 90 % lignin. Extractives as saturated fatty acids, palmitic and stearic acid plus lignans (which is interpreted as a byproduct from lignin degradation) do not degrade remarkable during wastewater treatment. Flocculation of COD is one way to reduce the discharge to the recipient. Addition of 2,6 g/l PAX-18 (a high charged aluminum complex) to the wastewater from the bleaching plant gives a reduction of 40 % COD and 50 % lignin in laboratory scale and it is recommended to study further. Time related studies of BOD show that the microorganisms need five days to degrade organic material and the hydraulic retention time in the aerated lagoon has to be guaranteed.</p> / <p>Vid massa- och pappersframställning åtgår stora mängder vatten. Det processberörda avloppsvattnet innehåller mycket föroreningar varför det måste renas innan det släpps ut till recipienten. I mars 2004 startades ett nytt väteperoxidblekeri vid SCA Graphic Sundsvall AB, Ortvikens pappersbruk varvid produktionen av blekt termomekanisk massa ökade och den biologiska reningen belastades hårdare. Blekning löser ut vedämnen från massan och bidrar således till ökad mängd syreförbrukande ämnen i avloppet. För att upprätthålla reduktionen av syreförbrukande ämnen (COD, BOD) tillförs ren syrgas till den luftade dammen. I november samma år utökades den externa reningsanläggningen med ett biologiskt försteg, en s.k. multibioanläggning bestående av ett frisimmarsteg, ett bärarsteg samt ett selektorsteg. COD-belastningen in till den luftade dammen minskade och tillförseln av ren syrgas kunde reduceras.</p><p>Examensarbetet har utförts vid SCA Graphic Research AB, Sundsvall med syftet att kemiskt karaktärisera avloppsvattnets sammansättning av kolhydrater, lignin och extraktivämnen och dess inverkan på vattnets grad av biologisk nedbrytbarhet. Analyser har gjorts på totalprov, suspenderande ämnen samt kolloidalt och löst material via fraktionering med hjälp av GF/A- och ultrafiltrering. Analyser gjordes dels på processvatten från blekerierna och dels på avloppsvatten under reningsprocessen. Resultaten visar att den kemiska sammansättningen hos löst material har större inverkan på avloppsvattnets grad av nedbrytbarhet än den absoluta halten av syreförbrukande ämnen. En hög andel lignin ger ett mer svårnedbrytbart vatten. Suspenderat material är vidare mer svårnedbrytbart än de lösta fraktionerna. Analys av suspenderande substans hos blekpressat visar att andelen lignin är omkring 41 % medan arkiverade analysresultat på den lösta fasen visar ett innehåll på omkring 29 %. Det tyder alltså på en betydligt högre andel lignin i den partikulära fasen jämfört med den lösta, vilket i kombination med att materialet inte är lika lättillgängligt för mikroorganismerna kan förklara den låga bionedbrytbarheten. Om COD-utsläppet ska minskas bör inkommande flöde av löst lignin och suspenderande substans till den biologiska reningen reduceras. COD-halten i utgående avloppsvatten till recipienten utgörs av omkring 90 % lignin. De extraktivämnen som inte bryts ned är mättade fettsyror, exempelvis palmitin- och stearinsyra samt lignan, vilket antas bildas som restprodukt vid degradering av lignin. Flockning av syreförbrukande ämnen är ett sätt att gå till väga för att minska utsläppet av dessa till recipienten. Genom tillsats av 2,6 g/l PAX-18 (ett högladdat aluminiumkomplex) till blekeriavloppet kunde 40 % COD och 50 % lignin reduceras. Flockningsförsöket är gjort i laboratorieskala vid rumstemperatur och ytterligare utvärdering rekommenderas. Tidsstudier av BOD visar att mikroorganismerna behöver fem dagars uppehållstid för att hinna bryta ned organiskt material i avloppsvattnet, varför omloppstiden i den luftade lagunen inte bör understiga denna tidsrymd.</p>

<p>In the process of making carton boards into Skoghall Mill, are great quantities of water being contaminated. This water has to be treated before it is possible to release into the recipient, Kattfjorden. One of the contaminations that is important to extract from the wastewater, is organic carbon (measured as TOC-total organic carbon) because microbiological breakdown can lead to the bottom becomig free of oxygen.</p><p>The wastewater treatment at Skoghall Mill is done through an external wastewater treatment that is located at the factory. The biological treatment (aerated lagoon) is a 140 000 m3 water pool with surface aerator, which is give oxygen to the water. In the lagoon live microorganisms who performs the biggest part of the TOC-reduction.</p><p>One problem with the lagoon is that the treatment of TOC is considerably worse during wintertime than during summertime. The reduction is during wintertime only 40 %, while during summertime it is about 70-80 %. This seasonal variation can to a large extent be explained by, that the water temperature in the lagoon decreases wintertime. The low water temperature does that the biological activity in the lagoon is reduced, which reduces the TOC-reduction. A second reason can also be that the microorganisms do not have enough bioavailable nutrients that is needed for growth of a new biomass.</p><p>In this thesis the need of nutrient has been examined. In two test pools, addings of nutrient were being done, to come to the conclusion of a good dosage of nutrient which would lead to a larger reduction of TOC, without enlarged quantities of nitrogen/phosphorus in the outgoing water. One of the test pools hold a summer temperature (30°C), and the other test pool hold a winter temperature (10°C). The test was performed this way to see if there would be any difference in the need of nutrient between summertime and wintertime.</p><p>The most important conclusion was that a nutrient dosage to the Skoghall aerated lagoon, rise the TOC-reduction wintertime. It was also concluded that it was foremost the nitrogen that contributed to the raised TOC-reduction, and nitrogen is thereby considered to be the growth restraining element wintertime. It seemed like phosphorus had been overdosed during the tests, while enlarged halts of the substance could be seen in the outgoing water, and an optimal dosage of phosphorus could not be done. The recommendation that came as a results from the tests, was that during wintertime add nitrogen and phosphorus according to TOC:N:P-quota 100:0,75:0,10. To the summer pool was no considerable improvement of the TOC-reduction seen, as a result of the nutrient addings. It is also no reason to dosage nutrients in summertime.</p> / <p>Vid tillverkning av kartong och pappersmassa på Skoghalls Bruk förorenas stora mängder vatten, som därmed måste renas före utsläpp till recipienten, Kattfjorden, en vik i Vänern. En av de föroreningar som är viktig att avlägsna ur avloppsvattnet är organiska kolföreningar (TOC-total organic carbon) eftersom det vid mikrobiologisk nedbrytning av TOC åtgår syre vilket kan leda till att sjöbotten blir syrefri.</p><p>Rening av avloppsvatten på Skoghall Bruk sker genom en extern reningsanläggning som är placerad på bruket. Det biologiska reningssteget i reningsanläggningen är en s.k. luftad damm. Detta är en 140 000 m3 stor vattenbassäng med ytluftare som syresätter vattnet. I dammen lever mikroorganismer vilka utför den största delen av TOC-reduktionen i brukets reningsanläggning.</p><p>Ett problem med dammen är att reningen av TOC är betydligt sämre vintertid än sommartid. Reduktionen av det till dammen inkommande TOC, är vintertid endast ca 40 % medan den sommartid ligger kring 70-80 %. Denna årstidsvariation kan till stor del förklaras av att vattentemperaturen i dammen sjunker vintertid. Den låga temperaturen medför att den biologiska aktiviteten i dammen sjunker, vilket hämmar TOC-reduktionen. En annan orsak till en låg TOC-reduktion kan vara att det för mikroorganismerna råder brist på biotillgängliga närsalter (kväve och fosfor) som behövs för tillväxt av ny biomassa.</p><p>I detta examensarbete har det undersökts behovet av närsalter för att höja TOC-reduktionen. I två laborationsdammar (ca 20 l) skedde doseringar av närsalter i syfte att finna en bra doseringskvot som innebar en ökad reduktion av TOC, utan att det blev förhöjda kväve-/fosforhalter i utgående vatten. En av laborationsdammarna höll sommartemperatur (ca 30°C) och en höll vintertemperatur (ca 10°C) vilket gjordes för att undersöka om det var skillnad av närsaltsbehovet mellan sommar och vintertid.</p><p>Den viktigaste slutsatsen av försöken var att en närsaltsdosering till Skoghalls luftade damm höjer TOC-reduktion vintertid. Det konstaterades att det var kvävet som främst bidrog till den ökade TOC-reduktionen och kväve anses därmed vara det tillväxtbegränsande ämnet vintertid. Fosfor tycktes ha överdoserats under försöken, då det sågs förhöjda halter i utgående vatten, och en optimal dosering av fosfor kunde inte avgöras. Den rekommendation som föll ut av de laborativa försöken var att vintertid dosera kväve och fosfor enligt TOC:N:P-kvot 100:0,75:0,10. Till sommardammen sågs inte någon förbättring av TOC-reduktionen till följd av närsaltstillsatserna, vilket innebär att närsaltsdoseringar sommartid är obefogat. Vidare sågs tendenser till att slammets sedimentationsegenskaper, hos framförallt vinterdammen, blev bättre till följd av närsaltsdosering, men brist på mätdata medför att det är svårt att dra slutsatser om det verkligen varit så.</p>

On se propose d'étudier l'hydrosystème Vaccarès, partie centrale du delta du Rhône, parfait exemple d'interrelations fortes entre l'homme et le milieu naturel. L'approche s'est déroulée en trois parties. L'acquisition et le traitement de données hydrologiques nous ont permis de caractériser la dynamique hydro-saline de ce système complexe. A partir d'une analyse plus approfondie nous avons établi les bilans hydro-salins et sédimentaires à l'échelle du complexe lagunaire. Grâce à un suivi de 18 années, les bilans sédimentaires dévoilent un déficit sédimentaire de 19 500 tonnes quand on ne prend pas en compte les apports exceptionnels des eaux d'inondation en 1993 et 1994. Un tel déficit, s'il perdure, ne fera qu'aggraver le différentiel d'altitude entre la mer et le delta, entrainant par la force des choses une salinisation du système non désirée par la plupart de ses acteurs. Dans un deuxième temps, nous avons procédé à l'implémentation et à la validation du modèle hydrodynamique du complexe lagunaire du Vaccarès. Son utilisation s'est tournée vers une complémentarité avec le modèle conceptuel de l'Hydrosystème Vaccarès. Ce dernier, baptisé Hydro-CAM, après avoir bénéficié d'une phase de calage et validation, a été exploité afin de tester la dynamique du système dans une démarche prospective. L'objectif ici, qui constitue le troisième temps de ces travaux de thèse, a été d'explorer par simulation les trajectoires possibles d'évolution de l'hydrosystème en termes de bilan d'eau et de sel, et ce d'après des scénarios construits sur les paramètres hydro-climatiques (changement climatique, augmentation du niveau marin) et anthropiques / The studied site is the Vaccarès hydrosystem, the central part of the Rhône delta and a good example of strong relationship between humans and a natural area. Through the data acquisition and data processing, we characterised the hydro-saline dynamic of this complex hydrosystem from 1993 to 2008. From a further analysis, we established first the hydro-saline and sedimentary balance across the lagoon complex. Through a monitoring of 16 years, the sedimentary balance revealed a sediment deficit of about 19'500 tons when we disregard the outstanding contributions of flooding waters in 1993 and 1994. If this deficit persists, the difference in altitude between the sea and the delta will tend to increase. This will result by a salinization of the system, unwanted by the most of his actors. To investigate these consequences, we conceived a hydrodynamic model of the Vaccarès lagoon complex, capable to simulate water levels and salinities. The model, named Hydro-CAM, was calibrated and validated in terms of water levels and salinities in three sub-units of the lagoon complex. It was then used to test the system dynamics in a prospective approach. The objective in this thesis work was to explore by simulation the possible trajectories of the evolution of the Hydrosystem in terms of water and salt balance. Simulations were based on scenarii constructed from climate parameters and anthropogenic parameters (water management, constructions, land use on drainage basins, etc.). The results revealed the vulnerability of this complex system to various risks which it is already facing and for which the intensification and/or increase can be expected in the future