Les plages de sable sont des écosystèmes dynamiques couvrant 70% des côtes mondiales. Ces systèmes abritent un cortège spécifique unique et assurent des fonctions essentielles de nourricerie, de nurserie et d’épuration des eaux. Or à proximité des côtes, la population humaine est en développement constant ce qui accroît les multiples pressions d’origine anthropique sur les écosystèmes côtiers. L’apport en excès de nutriments constitue une menace majeure qui peut se traduire par le développement d’importantes biomasses de macroalgues opportunistes (eutrophisation). La fréquence et l’intensité de ces blooms, communément formés de chlorophycées à court cycle de vie (ulves) et appelés marées vertes (MV), s'amplifient sur les côtes françaises et dans le Monde menaçant le fonctionnement de systèmes prépondérants et uniques.La plupart des études visant à déterminer les effets des MV sur la structure et le fonctionnement d’écosystèmes sédimentaires ont été conduites dans des environnements abrités, micro- ou atidaux. Cette problématique est restée presqu’inexplorée dans des écosystèmes plus dynamiques (systèmes ouverts et macrotidaux) en raison des difficultés de mise en place d’échantillonnage et de détection des effets de stress d’origine anthropique, inhérentes à la variabilité de ces systèmes. Cette thèse a donc eu pour objectif principal de combler ce manque et produire des connaissances en étudiant les réponses in situ des communautés benthiques de plages de sable fin macrotidales en présence ou non de MV. Quatre études ont été menées à différentes échelles spatio-temporelles et en considérant différents compartiments biologiques pour répondre à cette question générale.Ce travail de thèse montre qu’à l’échelle de la région Bretagne (variabilité intégrée sur 2700km de côtes et 7 ans) les communautés benthiques d’écosystèmes dynamiques sont modifiées significativement et de manière conservative par la présence de MV. Ce travail démontre aussi que les marées vertes impactent différemment la faune benthique en fonction du type d’habitat (plages semi-exposées vs. exposées), de la profondeur (mediolittoral vs. infralittoral), et du compartiment biologique (macrofaune benthique vs. juvéniles de poissons plats). Ces comparaisons ont permis d’identifier la faune benthique de médiolittoral inférieur des plages exposées comme étant le système le plus affecté par les MV. L’étude des variations à fine échelle spatio-temporelle de ce dernier montre que les caractéristiques faunistiques (uni- et multi-variées) sont modifiées le long d’un gradient de couverture d’algues vertes. Par exemple, la β-diversité décroît significativement le long de ce gradient. Afin d’explorer les processus pouvant expliquer ces modifications, et déterminer si ces changements ont des répercussions sur le fonctionnement de l’écosystème « plage de sable », les effets de l’accumulation d’ulves sur le réseau trophique à différent(e)s niveaux/échelles ont été mesurés. Les résultats de cette étude montrent qu’une importante biomasse d’ulves induit un changement de la structure entière du réseau trophique et une modification importante du fonctionnement trophique des plages. Les expérimentations menées au cours de cette thèse montrent que les changements observés sont induits par des effets directs (consommation de débris d’ulves) et indirects (modifications d’autres sources de nourriture) de la présence des MV.Cette thèse propose un cadre de travail visant à mieux détecter les effets de stress anthropiques sur la structure et le fonctionnement d’écosystèmes dynamiques. Dans un contexte de changement global forçant les écosystèmes à faire face à de multiples stress, cette approche pourrait se révéler particulièrement utile pour démêler, comprendre et prédire les effets de perturbations induites par les activités humaines sur le fonctionnement des écosystèmes et constituer une aide à la gestion de ces environnements particuliers. / Highly dynamic systems, often considered as resilient systems, are characterised by abiotic and biotic processes under continuous and strong changes in space and time. Because of this variability, the detection of overlapping anthropogenic stress is challenging. Coastal areas harbour dynamic ecosystems in the for of open sandy beaches, which cover the vast majority of the world’s ice-free coastline. These ecosystems are currently threatened by increasing human-induced pressure, among which mass-development of opportunistic macroalgae (mainly composed of Chlorophyta, so called green tides), resulting from the eutrophication of coastal waters. The ecological impact of opportunistic macroalgal blooms (green tides, and blooms formed by other opportunistic taxa), has long been evaluated within sheltered and non-tidal ecosystems. Little is known, however, on how more dynamic ecosystems, such as open macrotidal sandy beaches, respond to such stress. This thesis assesses the effects of anthropogenic stress on the structure and the functioning of highly dynamic ecosystems using sandy beaches impacted by green tides as a study case. The thesis is based on four field studies, which analyse natural sandy sediment benthic community dynamics over several temporal (from month to multi-year) and spatial (from local to regional) scales. In this thesis, I report long-lasting responses of sandy beach benthic invertebrate communities to green tides, across thousands of kilometres and over seven years; and highlight more pronounced responses of zoobenthos living in exposed sandy beaches compared to semi-exposed sands. Within exposed sandy sediments, and across a vertical scale (from inshore to nearshore sandy habitats), I also demonstrate that the effects of the presence of algal mats on intertidal benthic invertebrate communities is more pronounced than that on subtidal benthic invertebrate assemblages, but also than on flatfish communities. Focussing on small-scale variations in the most affected faunal group (i.e. benthic invertebrates living at low shore), this thesis reveals a decrease in overall beta-diversity along a eutrophication-gradient manifested in the form of green tides, as well as the increasing importance of biological variables in explaining ecological variability of sandy beach macrobenthic assemblages along the same gradient. To illustrate the processes associated with the structural shifts observed where green tides occurred, I investigated the effects of high biomasses of opportunistic macroalgae (Ulva spp.) on the trophic structure and functioning of sandy beaches. This work reveals a progressive simplification of sandy beach food web structure and a modification of energy pathways over time, through direct and indirect effects of Ulva mats on several trophic levels. Through this thesis I demonstrate that highly dynamic systems respond differently (e.g. shift in δ13C, not in δ15N) and more subtly (e.g. no mass-mortality in benthos was found) to anthropogenic stress compared to what has been previously shown within more sheltered and non-tidal systems. Obtaining these results would not have been possible without the approach used through this work; I thus present a framework coupling field investigations with analytical approaches to describe shifts in highly variable ecosystems under human-induced stress.

L'objectif de cette thèse est l'étude du régime alimentaire de poissons côtiers commerciaux et la compréhension de l'utilité des isotopes stables du carbone (δ13C) et de l'azote (δ15N) dans l'étude des niches trophiques et de l'occupation des habitats côtiers par les poissons dans le sud-ouest de l'océan Indien. Dans la Baie de La Possession, les espèces représentatives des récifs artificiels immergés en 2003 (Luljanus kasmira, Priacanthus hamrur et Selar crumenophthalmus) ingèrent surtout des proies pélagiques et partitionnent leurs niches trophiques afin de limiter la compétition. Les valeurs de δ15N sont positivement corrélées avec la taille des poissons, traduisant une contribution croissante des larves de poissons au régime alimentaire. Les isotopes stables de la matière organique particulaire (MOP) ont été analysés à microéchelle (< 10 km) dans la Baie de La Possession, à mésoéchelle (10aines de km) autour de La Réunion et, pour les muscles de poissons à macroéchelle (l00aines de km) le long,du plateau .des Mascareignes.et du cana1 du Mozambique. À microéchelle, le δ15N de la MOP ne varie pas; à mésoechelle, Il existe un enrichissement significatif en 15N dans le sud-ouest de l'île; à macroéchelle, les muscles des poissons s'enrichissent progressivement en 15N vers le nord. À microéchelle, la MOP est enrichie en 13C à faible profondeur; à mésoéchelle, les stations de l'est sont enrichies en 13C ; à macroéchelle, aucune tendance n'est observée. Ainsi, l'utilité des isotopes stables du carbone pour l'étude de l'utilisation des habitats côtiers est limitée à méso- et macroéchelle et les isotopes stables de l'azote constituent un outil plus pertinent à macroéchelle / The aim of this thesis was to study the feeding habits of coastal fish species of commercial interest andto use stable isotopes of carbon (δ13C) and nitrogen (δ15N) to investigate the trophic niches of fish and their use of coastal habitats in the south-west Indian Ocean. In the Bay of La Possession, the species among the most abundant around the artificial reefs immersed in 2003 (Luljanus kasmira, Priacanthus hamrur and Selar crumenophthalmus) feed essentially on pelagic prey and partition their trophic niche to limit interspecific competition. There was also a positive correlation between fish size and muscle δ15N values due to fish larvae contributing more to the diet of fish with age. The stable isotopie composition of the particulate organic matter (POM) was measured at the microscale (< 10 km) in the Bay of La Possession, the mesoscale (10's of km) around Reunion Island and, for the fish muscles, at the macroscale 100’s of km) along the Mascarene plateau and the Mozambique channel. At microscale, POM δ15N values do not show any spatial variability; at mesoscale, POM is 15N-enriched in the south-west of Reunion Island; at macroscale, fish muscles are gradually 15N-enriched towards the north. At microscale, POM shows a 13C-enrichment on the shallowest station; at mesoscale, stations on the east coast of the island are 13C-enriched compared to the west; at macroscale, POMδ13C values are not significantly correlated with latitude. Thus, the stable isotopes of carbon do not seem to be appropriate for the study of fish coastal habitat use at the meso- and macroscale, and the stable isotopes of nitrogen represent a better indicator of fish habitat use at the macroscale.

1 Abstract This thesis presents an analysis of fossil plants from the Cenomanian Peruc-Korycany Formation of the Bohemian Cretaceous Basin and from the Bückeberg Formation of the Lower Saxony Basin in Germany. Based on earlier studies, both areas provide sediments that are considered to have developed in tidally influenced fluvial systems. Studied fossil plants are represented by ginkgoalean plant leaves (Ertemophyllum, Tritaenia), branches of conifers (Frenelopsis) and lauroid angiosperms (Eucalyptolaurus). Frenelopsis, Eretmophyllum and Tritaenia are considered to be halophytic plants, while Lauroid angiosperms were considered to grow in fresh water conditions. The fossil plants were studied using cuticle analysis and two methods of stable carbon isotope analysis: Bulk carbon isotope analysis and Compound Specific Isotope analysis. For cuticle analysis samples were observed and documented macroscopically and microscopically. To specify the environmental conditions, recent samples from three salt marshes in Great Britain were studied and analysed using the same methods as the fossil samples. The data from all observations and measurements were processed and their interpretation supported the modelled environment based on the sedimentological data. Frenelopsis were growing in a haline environment with low...

La méiofaune joue un rôle important dans le fonctionnement des habitats benthiques à substrat meuble (ex. flux de matière) en relation avec sa production élevée, sa position trophique intermédiaire et les importants transferts d’énergie vers les niveaux trophiques supérieurs qui y sont lié. Les relations trophiques et les flux de matière organique liés à la méiofaune restent néanmoins mal connus ou peu pris en compte. Afin de mieux appréhender le rôle de la méiofaune, la structure des communautés et les relations trophiques entre les sources de nourriture et ces consommateurs ont été déterminées dans cinq habitats à substrat meuble (i.e., vasière nue, herbier, zone à sables) de la baie de Marennes-Oléron, France, et de la baie de Sylt-Rømø, Allemagne, en tenant compte des variations temporelles. Le peuplement de méiofaune s’est trouvé être dominé par les nématodes et les copépodes benthiques. Les biomasses de microphytobenthos et de matière organique du sédiment sont apparues comme étant deux facteurs structurants pour les communautés. L’utilisation combinée de différents traceurs de la matière (i.e., isotopes stables, acides gras) a démontré que le microphytobenthos et les bactéries étaient les ressources trophiques majeures de la méiofaune dans les cinq habitats étudiés. Les mesures réalisées sur la structure des communautés et les données issues des traceurs de la matière ont été implémentées dans des modèles de réseaux trophiques. Dans tous les habitats, ces modèles ont mis en évidence que le flux de carbone dominant était issu du microphytobenthos, ceci démontrant les très faibles changements de comportements alimentaires malgré les importantes différences de sources trophiques en termes de disponibilité et de production des sources de nourriture entre ces différents habitats. Tous les groupes trophiques de nématodes, à l’exception des déposivores sélectifs, étaient particulièrement sélectifs et s’alimentaient majoritairement à partir de microphytobenthos, ceci étant à l’origine d’une forte production et d’un court temps de renouvellement de la méiofaune. En conclusion, cette thèse démontre le rôle important de la méiofaune dans les habitats à substrat meuble ainsi que l’importance de la relation trophique entre le microphytobenthos et la méiofaune dans le fonctionnement de ces réseaux trophiques. / Meiofauna play an important role in ecosystem processes in soft-bottom benthic habitats, e.g. food web dynamics, related to their highproduction, their intermediate trophic position and the energy they transfer towards higher trophic levels. The trophic linkages and flows of organic matter related to the meiofauna remain poorly known or taken into account. To better assess the role of meiofauna, the community structure and trophic relationships between food sources and meiofauna were determined in five intertidal soft-bottom habitats (i.e., mudflat, seagrass bed, sandflat) of the Marennes-Oléron Bay, France, and the Sylt-Rømø Bight, Germany, taking temporal variations into account. Meiofauna communities were dominated by nematodes and benthic copepods. Biomass of microphytobenthos and of sediment organic matter were two of the major drivers of community structure. The combination of trophic markers (i.e., stable isotopes, fatty acids) demonstrated that microphytobenthos and bacteria were the major food sources of meiofauna in the five habitats. Information from community structure assessments and trophic marker analyses were implemented in food web models. In all habitats, these models demonstrated that the main flow of carbon to meiofauna originated from microphytobenthos, highlighting negligible changes in meiofauna feeding behavior besides the large differences in availability and productivity of food sources between these habitats. All trophic groups of nematodes, except for selective deposit feeding nematodes, were highly selective and mainly fed on microphytobenthos, resulting in a high production and a short turn-over time of meiofauna. In conclusion, this thesis demonstrated the important role of meiofauna in soft-bottom habitats as well as the importance of the trophic pathway from microphytobenthos to meiofauna in the functioning of these food webs.

The purpose of this thesis is to show that stable isotope analysis can be used to predict K’inich Yax K’uk Mo’s stable isotope measures based on Stuart’s (2007) hypothesis that K’inich Yax K’uk Mo’, the dynastic founder of the Copan royal lineage, was a Caracol lord. There is significant and convincing evidence that K’inich Yak K’uk Mo’ had a non-Copanec origin. Stable isotope analysis is a tested and reliable method for detailing diets and migratory paths of ancient humans and this theory is applied as a predictor of the stable isotope measures of K’inich Yax K’uk Mo’, if he did in fact originate in Caracol. The literature is rich with explanations of stable isotopes and the writings of a few stalwarts in the field were utilized to gain an understanding of the associated technologies and techniques utilized in its analysis. Data from the Copan (Whittington and Reed 1997) and Caracol (Chase and Chase 2001) stable isotope studies were utilized to show the application of stable isotope analysis in areas “associated” with K’inich Yax K’uk Mo’ and to illustrate how the palace diet identified by Chase and Chase (2001; Chase et al. 2001) could be aligned with the Stuart hypothesis to predict the stable isotope ranges for K’inich Yax K’uk Mo’.

Groundwater chemistry on the Niagara Peninsula has been identified as highly mineralized in comparison to groundwaters collected from the same bedrock formations elsewhere in southern Ontario. Three geochemical zones were discerned using hierarchical cluster analysis and other geochemical and isotopic methods. The Escarpment Zone, located along the Niagara and Onondaga Escarpments, is characterized by unconfined aquifer conditions, parameters reflective of surficial contaminants, including road salt, and elevated HCO3, DOC, NO3-, coliform bacteria and tritium. In contrast, in the Salina Zone thick, low-permeability sediments and gypsiferous bedrock results in highly mineralized groundwaters with Ca-SO4 geochemical facies and elevated S2-, Ca2+, Mg2+, K+, Na+, SO42-, Cl-, Br-, Sr2+, NH4+ and CH4. The Guelph Zone contains the lowest electrical conductivity of the three zones and elevated F-. Outliers exist with groundwater geochemistry that differs from the local geochemical zone and the host aquifer. These sites have elevated SO42- (>1000 to 5200 mg/L) with depleted δ34SSO4 (-2.2 to 14.3‰ VCDT) signatures that differs starkly from Devonian and Silurian evaporites (~20 to 32 ‰) in the host formations. This exogenic SO4 was identified in a cross-formational northeast – southwest linear trend crossing three major groundwater flow systems. The lack of down-stream impact in these systems and tritium groundwater ages that are typically only decades old indicate a young, non-geological origin and implicate anthropogenic activities. Additionally, nine samples were identified with elevated methane concentrations and δ13CCH4 signatures within the thermogenic range. As thermogenic methane is not produced within shallow aquifers and would be short-lived in the presence of the ubiquitous sulfate, these samples imply recent upward migration of methane from depth through vertical conduits. Taken together, the evidence supports large-scale upward movement of fluids in the centre of the Niagara geochemical anomaly and more sporadic upward transport of gases over a wider area of the peninsula. The most likely vector is through corroded and leaking casings or boreholes of abandoned (century) gas wells that are common across the peninsula. / Thesis / Master of Science (MSc)

Use of Re-Os systematics in sulfides from the Bagdad porphyry Cu-Mo deposit provide information on the timing of mineralization and the source of the ore -forming elements. Analyzed samples of pyrite, chalcopyrite and molybdenite mainly from the quartz monzonite and porphyritic quartz monzonite units are characterized by a moderate to strong potassic alteration (secondary biotite and K- feldspar). Rhenium concentrations in molybdenite are between 330 and 730 ppm. Two molybdenite samples from the quartz monzonite and porphyritic quartz monzonite provide a Re-Os isotope age of 71.7 ± 0.3 Ma. A third sample from a molybdenite vein in Precambrian rocks yields an age of 75.8 ± 0.4 Ma. These molybdenite ages support previous suggestions of two mineralization episodes in the Bagdad deposit. An early event at 76 Ma and a later episode at 72 Ma. Pyrite Os and Re concentrations range between 0.008-0.016 and 3.9-6.8 ppb, respectively. Chalcopyrite contains a wide range of Os (6 to 91 ppt) and Re (1.7 to 69 ppb) concentrations and variable ¹⁸⁷Os/¹⁸⁸Os ratios that range between 0.13 to 22.27. This variability in the chalcopyrite data may be attributed to different copper sources, one of them the Proterozoic volcanic massive sulfides in the district, or to alteration and remobilization of Re and Os. Analyses from two pyrite samples yield an eight point isochron with an age of 77 ± 15 Ma and an initial ¹⁸⁷Os/¹⁸⁸Os ratio of 2.12. This pyrite Re-Os isochron age is in good agreement with the molybdenite ages. We interpret the highly radiogenic initial 1870s/188Os as an indication that the source of Os and, by inference, the ore-forming elements for the Bagdad deposit, was mainly the crust. This conclusion agrees with previous Pb and Nd isotope studies and supports the notion that a significant part of the metals and magmas have a crustal source.

La tsavorite, grossulaire vert à V-Cr-Mn, est contenue dans des gneiss et roches calco-silicatées graphiteux, souvent associés à des marbres dolomitiques, et appartenant à la ceinture métamorphique néoprotérozoïque mozambicaine. La tsavorite se trouve soit dans des nodules ou des veines de quartz (gisements primaires), soit dans des placers (gisements secondaires). L'étude minéralogique des tsavorites propose un nouveau protocole de certification de leur origine géographique, à partir du rapport V/Cr, de la teneur en Mn et du [delta]18 O. L'étude des gisements de Lemshuku et Namalulu en Tanzanie montre que le métamorphisme des protolithes sédimentaires riches en matière organique et évaporites s'est effectué à P = 7,0 ± 0,4 kbar et T = 677 ± 14°C, à 634 ± 22 Ma (datation U-Th-Pb sur monazite). Le bâti métamorphique s'est refroidi vers 500 Ma (datation 40Ar-39Ar sur muscovite). Deux stades de métasomatose sont reliés à la formation de la tsavorite : (i) une métasomatose de diffusion formant les nodules à P = 5,0-7,4 kbar et T = 580-691°C; (ii) une métasomatose calcique d'infiltration contemporaine de la formation des veines de quartz à P = 3,6-4,9 kbar et T = 505-587°C. Ces dernières sont datées in situ par la méthode Sm-Nd à 606 ± 36 Ma. Les évaporites continentales, déposées dans une sabkha de côte marine avec des sédiments silico-calcaires, sont transformées en tsavorite dans le cas des nodules, alors que les sels fondus sont associés à la formation des veines de quartz. Les minéralisations sont contrôlées par la lithostratigraphie et la tectonique / Tsavorite, a (V, Cr, Mn)-bearing green grossular, is hosted by graphitic gneisses or calc-silicates, often asssociated with dolomitic marbles, and belonging to the Metamorphic Neoproterozoic Mozambique Belt. Tsavorite is found either as nodules or in quartz veins (primary deposits), or in placers (secondary deposits). The mineralogical study of tsavorites suggests a new protocol to certificate their geographical origin, based on the V/Cr ratio, Mn content and delta18O. The study of the Lemshuku and Namalulu deposits in Tanzania has shown that the metamorphism of organic matter-rich and evaporites-rich sedimentary protoliths occurred at P = 7.0 ± 0.4 kbar and T = 677 ± 14°C, at 634 ± 22 Ma (U-Th-Pb dating on monazite). The metamorphic series cooled down at around 500 Ma (40Ar-39Ar dating on muscovite). Two metasomatic stages are linked to the formation of tsavorite : (i) diffusion metasomatism forming nodules at P = 5.0-7.4 kbar and T = 580-691°C; (ii) calcitic infiltration metasomatism forming quartz veins at P = 3.6-4.9 kbar and T = 505-587°C. These last have been dated in situ with Sm-Nd dating at 606 ± 36 Ma. Continental evaporites, deposited in a coastal marine sabkha with (Si, Ca)-bearing sediments, transformed into tsavorite in the case of the nodules, while the molten salts are associated with the formation of the quartz veins. The mineralisations are controlled by lithostratigraphy and structure

La salinidad y el estrés hídrico son los factores más importantes que limitan la producción de trigo duro, sobre todo en regiones áridas y semiáridas, como la región Mediterránea. El trigo duro es uno de los principales cultivos en el sur y este de la Cuenca Mediterránea, donde se cultiva frecuentemente en condiciones de secano y si es posible con riego deficitario, a menudo con agua de poca calidad, que junto a una elevada evapotranspiración, puede provocar una progresiva salinización del terreno. En este sentido, la mejora genética de trigo duro para una mejor adaptación a estas condiciones de estrés es una de las pocas alternativas viables. El objetivo general de esta Tesis es estudiar las bases fisiológicas y moleculares de las diferencias genotípicas en crecimiento potencial y tolerancia a la salinidad y el estrés hídrico. En un primer estudio (Experimento 1) publicado en “Functional Plant Biology” se investigó qué criterio fenotípico de selección era el más adecuado para seleccionar genotipos de trigo duro que crecieran mejor en condiciones de salinidad continuada. De esta forma se determinó la importancia de los isótopos estables como criterios eficientes para seleccionar genotipos tolerantes y susceptibles a la salinidad. Posteriormente, se realizó un segundo estudio (Experimento 2) donde se evaluó el efecto de la salinidad en la composición isotópica del carbono (δ13C) y el nitrógeno (δ15N) de genotipos de trigo duro y de dos amfiploides (un tritordeo y un triticale). Este trabajo está publicado en la revista “Journal of Experimental Botany”. En este segundo ensayo, la salinidad se aplicó durante la floración y el llenado del grano durante unas pocas semanas. Los resultados de este trabajo representaron la puesta a punto del estudio del comportamiento fisiológico del trigo duro durante la fase reproductiva y bajo diferentes combinaciones de salinidad y riego. Como continuación de los dos Experimentos (1 y 2) y en vista de los resultados obtenidos en el uso de las firmas isotópicas como criterio de evaluación bajo condiciones salinas, se planteó evaluar el uso combinado de la composición isotópica del carbono (δ13C), oxígeno (δ18O) y el nitrógeno (δ15N) en materia seca para observar las respuestas genotípicas de plantas de trigo duro sometidas a diferentes combinaciones de salinidad. Como contribución original, se elaboró un modelo conceptual de las tres firmas isotópicas juntas (δ13C, δ18O, δ15N) junto con características del metabolismo nitrogenado para explicar las diferencias genotípicas en tolerancia a distintas condiciones de salinidad y estrés hídrico. También se evaluaron las características fotosintéticas en relación con las firmas isotópicas y las actividades de enzimas clave del metabolismo nitrogenado. (Trabajo Publicado en la revista “New Phytologist”). Además de los resultados anteriores obtenidos, en esta Tesis se comparó la eficiencia de las firmas isotópicas del carbono, oxígeno y nitrógeno mediante dos vías: muestras de materia seca y muestras de fracción soluble en genotipos de trigo duro para la evaluación de diferencias genotípicas en tolerancia a diferentes condiciones de salinidad y regimenes hídricos. Posteriormente se analizó la respuesta genética de plantas de trigo duro a la salinidad evaluando el nivel de transcripción de genes específicos asociados a tolerancia a salinidad y estrés hídrico, junto a otros que codifican para enzimas claves del metabolismo nitrogenado. También se han estudiado las relaciones entre estas tasas de transcripción, las diferencias genotípicas en crecimiento, firmas isotópicas y actividades de enzimas del metabolismo nitrogenado. El trabajo ha mostrado la eficacia de los isótopos estables de carbono y del nitrógeno como herramientas de evaluación de la respuesta del trigo duro frente a la salinidad. / Inadequate irrigation for long term and under conditions of high evapotranspiration demand, combined with the use of poor water quality and the lack of adequate drainage frequently induces the salinization of arable land causing a significant increase in the area affected by salinity. Salinity is an environmental factor that limits in a remarkable manner the production of crops in many parts of the world, but especially in arid and semiarid regions like the Mediterranean. Under these conditions, which is often grown durum wheat improvement for tolerance to salinity under irrigation deficit may be one of the strategies to alleviate this problem. This Thesis shows that isotope compositions of carbon (δ13C), oxygen (δ18O), and nitrogen (δ15N) and the concentration of nitrogen in dry matter are potentially and effective criteria for discriminating between different growing conditions and between genotypes tolerant or susceptible to salt. Furthermore, the results of this study reflect the importance of nitrogen metabolism in tolerance to salinity. Additionally, this thesis develops a model relating genotypic tolerance to different conditions of salinity and drought with the signatures of the three isotopes (C, O, N), together with photosynthetic and transpiration exchanges and parameters key of nitrogen metabolism such as nitrogen concentration and activities of the glutamine synthetase and nitrate reductase. Finally, we study the relationship between the expression of genes potentially key in the tolerance to salinity and drought and genotypic variability in response to different combinations of these stresses.

The Station Creek Igneous Complex (SCIC) is one of the largest Middle-Late Triassic plutonic bodies in the northern New England Orogen of Eastern Australia. The igneous complex comprises of five plutons - the Woonga Granodiorite (237 Ma), Woolooga Granodiorite (234 Ma), Rush Creek Granodiorites (231 Ma) and Gibraltar Quartz Monzodiorite and Mount Mucki Diorite (227 Ma respectively), emplaced as high-level or epizonal bodies within the Devonian-Carboniferous subduction complex that resulted from a westward subduction along the east Australian margin. Composition of the SCIC ranges from monzogabbro to monzogranite, and includes diorite, monzodiorite, quartz monzodiorite and granodiorite. The SCIC has the typical I-type granitoid mineralogy, geochemistry and isotopic compositions. Its geochemistry is characteristics of continental arc magma, and has a depleted-upper mantle signature with up to 14 wt% supracrustal components (87Sr/86Srinitial = 0.70312 to 0.70391; Nd = +1.35 to +4.9; high CaO, Sr, MgO; and low Ni, Cr, Ba, Rb, Zr, Nb, Ga and Y). The SCIC (SiO2 47%-76%) has similar Nd and Sr isotopic values to island-arc and continentalised island-arc basalts, which suggests major involvement of upper mantle sourced melts in its petrogenesis. SCIC comprises of two geochemical groups - the Woolooga-Rush Greek Granodiorite group (W-RC) and the Mount Mucki Diorite-Gibraltar Quartz Monzodiorite group (MMD-GQM). The W-RC Group is high-potassium, calc-alkalic and metaluminous, whereas the MMD-GQM Group is medium to high potassium, transitional calc-alkalic to tholeiitic and metaluminous. The two geochemical groups of the SCIC magmas are generated from at least two distinct sources - an isotopically evolved Neoproterozoic mantle-derived source with greater supracrustal component (10-14 wt%), and an isotopically primitive mafic source with upper mantle affinity. Petrogenetic modeling using both major and trace elements established that the variations within respective geochemical group resulted from fractional crystallisation of clinopyroxene, amphibole and plagioclase from mafic magma, and late fractionation of alkalic and albitic plagioclase in the more evolved magma. Volcanic rocks associated with SCIC are the North Arm Volcanics (232 Ma), and the Neara Volcanics (241-242 Ma) of the Toogoolawah Group. The major and trace element geochemistry of the North Arm Volcanics is similar to the SCIC, suggesting possible co-magmatic relationship between the SCIC and the volcanic rock. The age of the North Arm Volcanics matches the age of the fractionated Rush Creek Granodiorite, and xenoliths of the pluton are found within epiclastic flows of the volcanic unit. The Neara Volcanics (87Sr/86Sr= 0.70152-0.70330, 143Nd/144Nd = 0.51253-0.51259) differs isotopically from the SCIC, indicating a source region within the HIMU mantle reservoir (commonly associated with contaminated upper mantle by altered oceanic crust). The Neara Volcanics is not co-magmatic to the SCIC and is derived from partial melting upper-mantle with additional components from the subducting oceanic plate. The high levels emplacement of an isotopically primitive mantle-derived magma of the SCIC suggest periods of extension during the waning stage of convergence associated with the Hunter Bowen Orogeny in the northern New England Orogen. The geochemical change between 237 to 227 Ma from a depleted-mantle source with diminishing crustal components, to depleted-mantle fractionate, reflects a fundamental change in the source region that can be related to the tectonic styles. The decreasing amount of supracrustal component suggests either thinning of the subduction complex due to crustal attenuation, leading to the late Triassic extension that enables mantle melts to reach subcrustal levels.