Managed realignment is now widely seen as an important part of coastal management strategy, as an environmentally sustainable, cost-effective alternative to traditional, hard defences. However, the trajectory of salt marsh development in managed realignment schemes remains uncertain and it is unclear how sites should be managed to fulfil both coastal defence and biodiversity objectives. In this study, the overarching aim is to find out ways in which we can create salt marshes that are self-sustaining and function as closely to natural ecosystems as possible, by considering the linked biogeomorphological processes in salt marsh ecosystems. Such an approach will improve predictions of habitat development and recommendations for future practice in managed realignment schemes. The first important question is: How do pre-alignment plant species growing within managed realignment sites respond to salt water inundation upon re-exposure to flooding? Understanding the responses of the terrestrial vegetation community to initial seawater flooding may improve predictions of the short-term transition into salt marsh vegetation. To answer this, the effects of seawater inundation on pre-existing vegetation are initially examined in a greenhouse experiment in Chapter 3. It was demonstrated that one common plant species component of many coastal grasslands, Trifolium repens, responds poorly to simulated seawater soil flooding, but the response is population-, i.e. ecotype-, specific; therefore, the species consequently has an adaptive capacity to withstand short periods of soil inundation by seawater. In addition, I look at how and why the vegetation community of a restored site transitions following the reintroduction of tidal water, including the response of the original community of non-salt marsh plant species to salt water inundation and subsequent salt marsh plant community reassembly. After three years of tidal inundation at South Efford managed realignment site (SEM), terrestrial vegetation had decreased in cover and nearly all species recorded on the adjacent natural marsh had colonised. However, the cover of salt marsh species was limited by waterlogging, caused by modifications to the tidal regime by a self-regulating tidal gate. This leads on to the second question: How do new engineering techniques alter the tidal regime and what specific aspects of the new regime drive plant community reassembly and sedimentation patterns? In Chapters 4, 5 and 6, three years of ecological and geomorphological development are investigated in response to a variable inundation regime imposed by regulated tidal exchange at SEM. Inundation of the marsh surface was very regular, but water levels were not deep enough to encourage sufficient morphological development, sedimentation nor hydrochory. In contrast, ecological development was limited by waterlogging. Balancing the tidal regime with the drainage efficiency of managed realignment sites may be the most likely scenario under which restored salt marsh will develop with maximum biodiversity benefits. Otherwise, further management techniques, such as the excavation of tidal channels, may need to be employed to improve site drainage. Consequently, the final question is: How can biodiversity be maximized on realignment sites through the use of different management techniques and site design? Tidal channels on a range of managed and natural sites were shown to improve the drainage efficiency of adjacent soils (particularly channels of greater width and/or higher Strahler order). Plant species diversity was generally higher on channel banks in managed realignment sites. On sites with highly reduced soils, the colonisation and establishment of halophytes could be advanced on the banks of tidal channels. Additionally, topographic heterogeneity introduced by tidal channels created a variety of habitat niches, which allowed a range of salt marsh species to establish in the absence of highly competitive species, such as Elymus repens. Results from this study could contribute to the generation of a number of recommendations for the implementation of managed realignment schemes, particularly regarding the excavation of tidal creek networks.

Salinity is a major abiotic stress in plants that causes significant reductions in crop yield. The need for improvement of food production has driven research to understand factors underlying plant responses to salt and mechanisms of salt tolerance. The aim of improving tolerance in traditional crops has been initiated but most crops can only tolerate a limited amount of salt in their systems to survive and produce biomass. Studies of naturally occurring high salt-tolerant plants (halophytes) are now being promoted for economic interests such as food, fodder or ecological reasons. Suaeda fruticosa, a member of the family Chenopodiaceae, belongs to a potential model halophyte genus for studying salt tolerance. However, published reports on the identification of genes, expression patterns and mechanisms of salinity tolerance in succulent halophytes are very limited. Next generation RNA-sequencing techniques are now available to help characterize genes involved in salinity response, along with expression patterns and functions of responsive genes. In this study, we have optimized the assembly of the transcriptome of S. fruticosa. We have annotated the genes based on their gene ontology characteristics and analyzed differential expression to identify genes that are up- and down-regulated in the presence of salt and have grouped the genes based on their putative functions. We also have provided evidence for groups of transcription factors that are involved in salt tolerance of this species and have identified those that may affect the regulation of salt tolerance. This work elucidates the characterization of genes involved in salinity tolerance to increase our understanding of the regulation of salt in a succulent halophyte.

En période hivernale, des fondants routiers sont épandus sur les chaussées afin de préserver la sécurité des usagers. Sous l'influence de divers paramètres, ces produits se retrouvent en partie dans l'environnement, le reste étant collecté par des systèmes de rétention des eaux de ruissellement routières. Or, les bassins de rétention ne sont pas conçus pour traiter ces fondants, et jouent uniquement un rôle de régulation des flux rejetés dans l’environnement. L’effet du NaCl sur l’environnement est néfaste, en raison de sa toxicité directe envers certains organismes et, indirectement parce qu’il contribue à augmenter la mobilité des ETM (Éléments Traces Métalliques), eux-mêmes toxiques. Ceci démontre un besoin d'assainissement particulier pour ces produits. L'objectif de cette thèse est d'étudier les transferts de NaCl par un bassin de rétention, mais également d'investiguer la possibilité d'utiliser la phytoremédiation comme base d'une solution d'assainissement des eaux de ruissellement routières. Le bassin de rétention choisi comme modèle est un bassin récent situé à Chenevières (Lorraine, France), en bordure d’une route nationale. La première partie du travail a porté sur la mesure et la caractérisation des transferts de NaCl dans ce bassin. L’eau a été collectée en entrée/sortie chaque semaine pendant 3 ans, et les concentrations en NaCl et ETM mesurées. Les conditions météorologiques et les données d’épandage de sel ont été suivies pour évaluer la proportion de sel effectivement transférée vers le réseau de collecte des eaux de ruissellement routières. Les résultats montrent que 25 à 50 % du sel épandu est effectivement collecté. De plus, les résultats sur la dynamique du NaCl prouvent que le bassin joue uniquement un rôle de rétention temporaire et de dilution avant rejet vers l’environnement. Ensuite, des mesures et analyses des sédiments du bassin et des sols de bord de route ont été conduites pour caractériser la spéciation et la mobilité des ETM dans ce contexte routier particulier. Dans ce cas précis, le NaCl n’a pas eu d’effet significatif sur la mobilisation des ETM, hormis le zinc (Zn). En revanche, il a provoqué la mobilisation d’autres ions majeurs. Concernant le traitement, les procédés conventionnels de dessalement d’eau sont trop coûteux et inadaptés. C’est pourquoi les potentialités d’une solution d’assainissement par phytoremédiation ont été explorées. Trois plantes halophytes ont été sélectionnées selon des critères permettant leur utilisation en contexte routier, Armeria maritima, Atriplex halimus et Atriplex hortensis L. Des expériences de germination/croissance ont été effectuées dans différentes conditions de salinité et de concentration en Zn pour évaluer leur tolérance à la salinité, à la présence de Zn et leurs capacités d’accumulation. Ces plantes ont montré une tolérance au NaCl dans des conditions de salinité représentatives de celles mesurées dans les réseaux d’assainissement routiers à Chenevières. De plus, les trois espèces accumulent dans leurs parties aériennes des quantités significatives de NaCl, ainsi que du zinc. L'utilisation des halophytes pour la phytodésalinisation en domaine routier s'avère être une technologie prometteuse pour répondre à la problématique de l'impact environnemental des fondants routiers. / During winter, deicing salts are spread on roads in order to preserve road safety for users. Under the influence of different parameters, these compounds are partly transferred to the environment, the rest of it being collected by the road runoff retention systems. However, road runoff retention ponds have not been designed for deicing salt treatment; they only play a role in the regulation of fluxes before their rejection into the environment. Furthermore, NaCl has a harmful impact on the environment, because of its toxicity to certain aquatic organisms and because it contributes to the increase of trace metal (TM) mobility, which are toxic as well. This shows the need for a specific treatment for these compounds. The objective of this research is to bring better understanding of deicing salt dynamics in a retention pond, but also to investigate the potential use of phytoremediation as a treatment solution for road runoff. A model retention pond was selected; it is located along a highway in Chenevières (Lorraine region, France). The first part of the work focused on the monitoring and the characterization of NaCl transfers in this pond. Water was weekly sampled for 3 years at the pond input and output and NaCl and TM concentrations were measured. Meteorological conditions and salt spreading data were monitored to appraise the salt fraction actually collected by the pond. Results showed that only 25 to 50 % of the spread salt is effectively collected. Moreover, results on NaCl dynamics proved that the pond only plays a role on transient storage and salt dilution before rejection into the environment. Moreover, measurements and analyses of sampled basin sediments and roadside soils were performed to assess speciation and TM mobility in this particular context. In this case, no significant effect of NaCl was recorded except for zinc (Zn); but major ions were mobilized. When it comes to treatments, conventional desalination technologies are too expensive and inappropriate in this context. Then, potentialities of phytodesalination were explored. Three halophyte plants were selected on the basis of specific criteria, allowing their use in road runoff context: Armeria maritima, Atriplex halimus and Atriplex hortensis L. Germination and growth experiments were run in various salinity conditions and in the presence/absence of Zn, in order to assess their tolerance to salt and Zn, as well as their accumulation abilities. These plants showed a high tolerance for NaCl in salinities in the range of those encountered in road runoff existing treatment systems at Chenevières. The three species accumulated significant amounts of NaCl and zinc in their aerial parts. The use of halophytes for phytodesalination of road runoff is a promising technique to address the issue of environmental impact of deicing salts.

Quatre espèces halophyles, Silene maritima, Carpobrotus edulis, Senecio cineraria et Limonium latifolium, ont fait l’objet d’études phytochimiques en procédant par fractionnement bioguidé. Nous avons ainsi identifié une trentaine de métabolites bioactifs, capables de limiter la production d’espèces réactives de l’oxygène qui interviennent dans le stress radicalaire et/ou inflammatoire et/ou de favoriser la lipolyse adipocytaire. La visualisation de l’impact du biotope sur le métabolome de Silene maritima nous a permis d’identifier des marqueurs jouant un rôle important dans la capacité adaptative de cette halophyte sous l’effet de stress environnementaux. L’analyse de profils métaboliques montre clairement qu’un même individu, récolté à des moments différents et/ou dans des biotopes différents, possède une composition phytochimique variable. Afin de tester l’effet d’éliciteurs sur la capacité biosynthétique de suspensions cellulaires de Silene maritima, nous avons eu recours à la biotechnologie végétale. Nous avons également développé des conditions de culture in vitro permettant l’initiation de cals à partir d’une halophyte protégée, Crambe maritima. Ces cals pourront in fine servir à initier des suspensions cellulaires, valorisables industriellement. / Four halophile species, Silene maritima, Carpobrotus edulis, Senecio cineraria and Limonium latifolium have been studied phytochemically by bioguided fractionation. This work led to the discovery of thirty biologically active compounds able to reduce the production of reactive oxygen species that occur during inflammatory and/or radical stress, and to promote the adipocytary lipolysis. The visualization of the biotope’s impact on the halophyte Silene maritima metabolome helped us to identify markers playing an important role in the adaptative capacity of plants under environmental stress. Analysis of metabolite profiles clearly shows that the same individual harvested at a different moment and/or from a different biotope possesses an extremely variable chemical composition. In order to test elicitor effect, we used plant biotechnology. Finally, we were able to develop in vitro culture conditions permitting initiation of callus from the protected halophile Crambe maritima. The obtained callus could serve to initiate cell suspension, which is suitable for industrial purposes.

Throughout the arid and semi-arid regions, researchers have been looking at different ways to deal with the salinity problem of the soil and water as well as feed for the livestock. Study 1 focused on a pilot project conducted in an irrigation district in Marana, AZ, USA, looking at using Reverse Osmosis (RO) concentrate on Atriplex lentiformis (quailbush) and then harvesting the plant to be tested for its possible use as a supplement in feed for livestock. Three irrigation treatments were tested based on the potential evapotranspiration rate (ET(o)): (1) plots irrigated at ET(o) adjusted daily via an on-site micrometeorology station; (2) plots irrigated at 1.5 ET(o) adjusted daily; (3) plots irrigated at a constant rate throughout the year based on the mean of annual ET(o). The plants produced 15-24 tons ha⁻¹ year⁻¹ of biomass and could be irrigated at the rate of ET(o), ca. 2 m yr⁻¹ at this location. It was concluded that irrigation of halophyte forage crops provide a viable strategy for extending water supplies and disposing of saline water in arid-zone irrigation districts. Study 2 focused on a field data from Study 1 and two greenhouse experiments. The greenhouse experiments were conducted in 2007 and 2010. The 2010 greenhouse trials, under well-watered conditions, showed that the apparent zero-point-salinity for yield was 47.3 g L⁻¹ TDS. An additional greenhouse experiment was conducted in which plants in sealed pots were grown to the wilting point on a single application of water. The experiment was conducted at different salinities to see if salinity and water stress were additive factors in reducing yield and Water Use Efficiency (WUE). To the contrary, yield and WUE actually increased as a function of salinity, perhaps due to conversion from C3 to C4 photosynthesis over the salinity range (noted in other studies with A. lentiformis). We conclude that xerohalophytes such as A. lentiformis could greatly extend the useful range of salinities under which forage crops can be grown in arid-zone irrigation districts.

Extensive coastal sabkhas in the northern Gulf of California in North America are colonized by Distichlis palmeri, an endemic perennial grass that produces a grain that was harvested as a staple food by native Cocopah people. Previous short-term trials have shown good vegetative growth but low grain yields. During outdoor trials under anaerobic saline soil conditions of paddy-style irrigation, D. palmeri exhibited high salt tolerance, grain and biomass production. Reproductive maturity was reached four years after initial establishment of plants from seed and a 1:3 mixture of male and female plants produced 231-310 g m⁻² of grain, with nutritional content similar to domesticated grains, confirming the feasibility of developing D. palmeri as a perennial grain and biomass crop for salinized soils and water supplies. Salicornia bigelovii Torr., a cosmopolitan annual coastal marsh succulent, produces seed with high oil content and has been suggested as a potential cash crop for fuel production from saline irrigation but its domestication and development into a cost effective commodity has been slow. A breeding and selection program for agronomic traits that will provide multiple landscape and ecosystem services that could enhance cost benefits of the agronomy of S. bigelovii was initiated during a two year period while producing seed for a pilot system at the Masdar Institute in Abu Dhabi, U.A.E. A concept for a saline landscape designed to consume and concentrate saline waste streams was developed and demonstrates the feasibility and potential to support agronomy of halophytes within a built landscape ecology akin to coastal marsh systems. Exploration and development of potential services halophytes could provide and field testing of selected halophytes for their potential to produce food, fuel, fiber and habitat under designed and managed domestication in our salinized soils with saline waste irrigation needs our continued investigation.

[Truncated abstract] Saltbush is one of the few types of forage that will grow on salt affected land but, sheep struggle to maintain weight when grazing saltbush mainly because of its high salt content. Therefore, a strategy to improve salt tolerance of sheep would be beneficial to the profitable use of revegetated saline land. This could be done by manipulating the dietary salt load of pregnant or lactating ewes which could 'program', or permanently alter the physiology of their offspring to allow them to cope better with a high-salt diet as adults. When rat dams consume a high amount of salt during pregnancy, the salt balance mechanisms of their offspring are 'programmed' due to suppression of the offspring's renin-angiotensin system in early development. If this occurs in offspring from ewes grazing saltbush, beneficial adaptations may be programmed in these offspring which could allow them to better cope with the high-salt content of saltbush. I tested the general hypothesis that offspring born to ewes that consumed a high-salt or saltbush diet from mid-pregnancy to early lactation would have an increased capacity to cope with salt that would allow them gain weight when grazing saltbush in later life. To test this hypothesis, I pair-fed ewes either a high-salt diet (14% NaCl) or control diet (2% NaCl) in an animal house from day 60 of gestation until day 21 of lactation. During the same period, I also conducted a field experiment where ewes grazed on saltbush (supplemented with barley) or on pasture (supplemented with lupins). ... This led to the high-salt offspring retaining more salt than control animals. In contrast, the renin activity of saltbush was consistently lower than pasture offspring which allowed them to excrete salt more rapidly. In experiment three, the saltbush offspring gained tissue weight after grazing saltbush for 8 weeks, whereas the offspring in the other three treatments lost weight. High-salt and saltbush offspring also had higher greasy fleece weights at 22 months of age than their respective control groups. Feeding saltbush to ewes from mid-pregnancy to early lactation induces physiological adaptations in their offspring that allow them to cope better with salt and gain weight when grazing saltbush as adults, supporting my hypothesis. However, contrary to expectations, the high-salt offspring did not gain weight when grazing saltbush because their physiological adaptations, such as salt retention, did not allow them to cope better with a salt load. The reason that saltbush offspring showed different adaptations to highsalt offspring is likely to be because saltbush contains not only NaCl but also high amounts of other minerals such as potassium, and other plant compounds, which may influence the adaptive responses of the offspring. This research has direct implications for farmers because it shows they could utilize otherwise unproductive saltland by grazing pregnant ewes on saltbush to 'program' their offspring to gain weight when they graze saltbush later in life.

Thesis (M.S. Animal Sciences)--University of Arizona, 1982. / Includes bibliographical references (leaves 38-41).

La pollution environnementale constitue un problème majeur pour les écosystèmes naturels et la santé publique. Récemment, la phytoremédiation a émergé comme une stratégie innovante, écologique et à faible coût. Elle consiste à utiliser les capacités des plantes à stocker ou/et à dégrader les polluants. Dans cette étude, des analyses physiologiques, biochimiques et métabolomiques, ont permis de montrer que les halophytes, une catégorie des plantes extrêmophiles, présentent une grande capacité à remédier la pollution engendrée par les Hydrocarbures Aromatiques Polycycliques (HAPs). D'autre part, la salinité modérée améliore leur capacité phytoremédiatrice. Ces résultats apportent de nouvelles données pouvant contribuer à l'amélioration de cette stratégie. / Halopytes, plants naturally adapted to high salt concentrations, have no clear definition, yet. Their cross-tolerance to abiotic stresses was reviewed in this work at the physiological, biochemical, and molecular levels, with a special emphasis on the mechanisms involved in their cross-tolerance to salinity and organic pollutants that could allow them a higher potential of xenobiotic phytoremediation as compared to glycophytes. In our experimental part, we compared in a first step some physiological and antioxidant responses to phenanthrene as well as its accumulation in the two related model plants Arabidopsis thaliana (glycophyte) and Thellungiella salsuginea (halophyte).In a second step, we investigated the effects of moderate salinity on the responses of the two species to phenanthrene considered as model Polycyclic Aromatic Hydrocarbon (PAH) molecule. Obtained results showed an improvement of phenanthrene-induced responses in the two plants, the effect being more marked in the halophyte. This observation was particularly related to higher antioxidant activities and the induction of more adapted metabolism as several accumulated metabolites are known to be involved in signaling and osmotic adjustment processes. In a final step, we studied the potential of the halophyte Cakile maritima to remediate an inert sand (to avoid the degradation of the pollutant by microorganisms or their interaction with the plant) highly contaminated with phenanthrene.

El Salitral de la Vidriera (Part. Villarino, Prov. Buenos Aires) presenta una gran cantidad de factores de estrés (sequía, salinidad, alta radiación, etc.) que impiden la implantación de muchas plantas; sin embargo, permite la existencia de otras que han logrado adaptarse a tales condiciones ambientales. El objetivo de esta tesis doctoral ha sido analizar la anatomía vegetativa de especies vegetales que conforman la comunidad xero-halófila que se desarrolla en dicho Salitral y la distribución espacial de las mismas en relación al gradiente de salinidad. A partir de esta relación se buscaron especies bioindicadoras que permitan estimar el grado de salinidad del suelo. Se ha estudiado la anatomía vegetativa (foliar y caulinar) de 35 especies pertenecientes a 15 familias botánicas. Hojas y tallos fueron tratados con técnicas tradicionales para estudios anatómicos y epidérmicos, así como también para la descripción de los macropatrones de cristales de oxalato de calcio. Se analizaron, además, muestras de la capa superficial del suelo a fin de cuantificar su salinidad. En gran parte de las especies estudiadas se identificaron características morfológicas y anatómicas que demuestran una alta adaptación al ambiente, siendo las hojas los órganos con mayor variedad de estas características. En general las adaptaciones están relacionadas con la reducción de la pérdida de agua por evapotranspiración y con los mecanismos de regulación de la concentración de sales. Entre las estrategias comunes pueden citarse: reducción del área foliar (por microfilia o plegamiento de las hojas), epidermis con células de paredes engrosadas, estomas pseudo-hundidos o protegidos por tricomas, tejido acuífero, etc. Particularmente en la organización del mesofilo se observaron diseños dorsiventrales, isolaterales y céntricos, siendo éste el carácter más variable entre los estudiados. En general en los tallos se encontraron caracteres que complementan los efectos de las variaciones anatómicas presentes en las hojas. Entre éstos pueden citarse: gran cantidad de tejidos de sostén mecánico (colénquima y esclerénquima) y rápido desarrollo de crecimiento secundario (típico o atípico). La distribución de las especies muestra una estrecha relación con las características del suelo. Ocho especies vegetales fueron consideradas como buenas bioindicadoras de salinidad debido a que su distribución espacial coincide con rangos estrechos de salinidad; con ellas se confeccionó una clave dicotómica que facilita su utilización como bioindicadores. Los estudios sobre especies vegetales de ambientes hostiles revisten especial importancia debido a los profundos cambios ambientales a los que se enfrenta el hombre; este conocimiento permitirá encontrar nuevas aplicaciones y/o utilidades para estas especies. / The Salitral de la Vidriera (Part. Villarino, Prov Buenos Aires) presents a lot of stress factors (drought, salinity, high radiation, etc.) that impede the implantation of many plants, allowing the existence of others which have successfully adapted to such environmental conditions. The objective of this thesis was to analyze the vegetative anatomy of plant species that form the xero-halophytic community of the mentioned salitral and the spatial distribution of these plants in relation with the salinity gradient. From this relationship, bioindicator species were sought to estimate the degree of soil salinity. The vegetative anatomy (leaf and stem) of 35 species belonging to 15 plant families were studied. Leaves and stems were treated with traditional techniques for anatomical and epidermal studies and also to describe their calcium oxalate crystals macropatterns. Samples of topsoil also were analyzed to quantify their salinity and then to find potential bioindicator species. In most of the studied species morphological and anatomical characteristics showed high adaptation to their environment, the leaves being the organs with the greatest variety of these characteristics. Adaptations are generally related to the reduction of water loss by evapotranspiration and mechanisms for regulation of salt concentration. The common strategies found include: reduction in leaf area (by microfily or folding of leaves), epidermal cells with thickened walls, pseudo-sunken stomata or protected by trichomes, aqueous tissue, etc. Particularly in the organization of the mesophyll were observed dorsiventral, isolateral and centric designs, this being the most variable character among those studied. In general stems characters complement the effects of anatomical variations present in the leaves. Among these may be mentioned: great development of mechanical supporting tissues (collenchyma and sclerenchyma) and rapid developing of secondary growth (typical or atypical). Relating the distribution of species with soil characteristics, it was observed that there is a relationship between them. Eight plant species were considered good salinity bioindicators, because their spatial distribution coincides with narrow ranges of salinity; they were compiled in a dichotomous key to simplify their use as bioindicators. Studies on plant species of hostile environments have particular importance due to profound environmental changes that men are facing to, this knowledge will contribute to find new applications and/or utilities for these species.