Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-04-13T17:01:22Z No. of bitstreams: 1 dissertacao_igor (1).pdf: 3140302 bytes, checksum: 75df9450209427176565cb75c2583678 (MD5) / Made available in DSpace on 2016-04-13T17:01:22Z (GMT). No. of bitstreams: 1 dissertacao_igor (1).pdf: 3140302 bytes, checksum: 75df9450209427176565cb75c2583678 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências-Geoquímica. Niterói, RJ / Com o objetivo de analisar a influência dos processos internos da plataforma continental sudeste do Brasil na composição isotópica das massas de água, apresentamos dados de isótopos estáveis (δ18O, δ13CCID e δD) e concentração de fosfato de um total de 32 estações. Os resultados foram comparados com observações no oceano aberto, a fim de identificar os principais desvios isotópicos. Como resultado, observou-se um elevado grau de mistura das principais massas de água: Água Subtropical de Plataforma (ASP), Água Central do Atlântico Sul (ACAS) e Água Tropical (AT), na maioria das amostras recolhidas. Este resultado foi relacionado aos processos de ressurgência, descarga de águas continentais e a mistura advectiva, que promovem a mistura entre as massas d’água da região. Posteriormente, a metodologia do triângulo de mistura revelou a contribuição das massas d’água em cada amostra. Dessa foram foi possível caracterizar isotopicamente as massas d’água: ASP (δ13CCID = 2,31 ± 0,41; δ18O = 0,22 ± 0,06); ACAS (δ13CCID = 1,30 ± 0,22; δ18O = 0,46 ± 0,10); AT (δ13CCID = 1,74 ± 0,24; δ18O = 0,88 ± 0,11). A associação dos isótopos estáveis com os parâmetros físicos e com a concentração de fosfato permitiu acessar a influência dos processos físico-biogeoquímicos sobre a distribuição isotópica na coluna d’água. Os resultados da correlação δ18O-salinidade mostraram a influência de processos costeiros na distribuição dos isótopos estáveis e sua distinção em comparação com o oceano aberto. A correlação observada entre δ13CCID-fosfato mostrou a predominância do fracionamento biológico como fator modulador dos valores de δ13CCID na plataforma. Além disso, foi possível testar as implicações paleoceanográficas relacionadas aos dados obtidos. Diferenças nas estimativas de paleosalinidade, paleotemperatura e paleoprodutividade mostraram ser resultantes da escolha de valores diferentes de δ18O da água (ASP, ACAS ou AT), ou na escolha da relação atual entre parâmetros, como δ13CCID-fosfato por exemplo / In order to analyze the influence of the internal processes of the southeastern continental shelf of Brazil in the isotopic composition of water masses, we present stable isotope data (δ18O, δD and δ13CDIC) and phosphate concentration of a total of 32 stations. The results were compared with observations in the open ocean in order to identify the main isotopic shifts. As a result, there was a high degree of mixing of the major bodies of water: Subtropical Shelf Water (SSW), South Atlantic Central Water (SACW) and Tropical Water (TW), in most of the samples. This result was related to the processes of upwelling, continental water discharge and advective mixing, which promote mixing between water masses of the region. Subsequently, the methodology of the triangle mixture indicated the contribution of water masses in each sample. Thus, it was possible to characterize the water masses: SSW (δ13CDIC = 2.31 ± 0.41, δ18O = 0.22 ± 0.06), SACW (δ13CCID = 1.30 ± 0.22, δ18O = 0 46 ± 0.10), TW (δ13CDIC = 1.74 ± 0.24, δ18O = 0.88 ± 0.11). The combination of stable isotope data with the physical parameters and the concentration of phosphate allowed to access the influence of physical and biogeochemical processes on the isotopic distribution in the water column. The results of the correlation δ18O-salinity showed the influence of coastal processes in the distribution of stable isotopes and their distinctiveness compared to the open ocean. The correlation observed between δ13CDIC-phosphate showed the predominance of biological fractionation factor as a modulator of values δ13CDIC in the shelf. Furthermore, it was possible to test the paleoceanographic implications related to data. Differences in paleosalinity, paleotemperature and paleoproductivity estimates shown to be derived from the choice of different values of δ18O water (SSW, SACW, TW), or the choice of the relation between the current parameters, such as for example δ13CDIC-phosphate

Située au Nord-Ouest de la Tunisie centrale, le bassin de Foussana du gouvernorat de Kasserine constitue une zone de transition entre la région tellienne pluvieuse au Nord et la région saharienne au Sud. Il est bordé par une série de reliefs de formes et de directions variées. Dans cette région aride à semi-aride, l’eau souterraine représente la principale réserve et ressource de production d’eau. Du point de vue tectonique, le bassin de Foussana est caractérisé par la présence de multiples failles. Les failles de direction NW-SE, dont la plus importante est celle qui s’aligne parallèlement à l’Oued Hatab (Faille de Foussana). Les failles qui bordent le fossé du côté est et du côté Ouest se placent dans la famille directionnelle NW-SE. Les failles de direction NE-SW, dont la plus importante est celle qui borde Jebel Chambi du côté sud, montrent une activité décrochante senestre à composante normale. Les failles de direction EW constituent la troisième famille de fracture ayant contrôlé l’évolution de cette structure effondrée. Le bassin d’effondrement de Foussana formé par le jeu de failles de direction NW-SE constitue une fosse subsidente comblée de dépôts MioPlioQuaternaires à caractère continental et renferment plusieurs niveaux aquifères avec des intercommunications latérales entre les grés miocènes et les niveaux Plio-Quaternaires le long des failles de bordure et par drainance le long de l’axe de la fosse matérialisé par l’oued El Hatab. Le Quaternaire couvre toute la cuvette. Sa constitution varie selon les régions, en bordure, nous retrouvons les éboulis de pente formés de gros éléments de calcaire sub- arrondis, parfois bien cimentés par de l’argile rouge. Ces dépôts laissent la place au centre de la cuvette de l’Oued Hatab à des dépôts plus fins constitués de sol sableux ou argilo - sableux avec une certaine proportion de limon. Dans les régions de bordure, les dépôts du PlioQuaternaire très grossiers sont directement superposés aux grès miocènes. Les aquifères profond du Pliocène (PQ2) et superficiel du Quaternaires (PQ1) sont susceptibles de constituer un aquifère unique, puisque leurs résistivités sont presque semblables, leurs salinités sont voisines, et leurs piézométries sont confondues. Les grès Miocènes varient d’une région à l’autre selon qu’on est dans les zones de bordures ou dans des fosses. Ils sont libres au Nord et au Sud de la plaine séparés par les deux grands accidents tectoniques. Les grès en affleurement sont non seulement plus grossiers mais aussi plus homogènes, ce qui attribue aux aquifères libres une grande perméabilité, contrairement aux aquifères des grès en charge où les alternances fréquentes d’argiles et de marnes réduisent énormément ce paramètre. Cette homogénéité croit également en profondeur. Dans l’optique de caractériser le fonctionnement du système hydrogéologique multicouche et de calculer un bilan hydrologique pour le système aquifère, une méthodologie multi techniques couplant l’ hydrochimie, l’isotopie et l’hydrodynamisme a été déployée. L’analyse détaillée des données hydrochimiques recueillies a mis en évidence la grande variabilité du fond géochimique local, directement fonction de la stratigraphie. Cette complexité stratigraphique induit une vision hydrogéologique complexe de nombreux corps aquifères. L’évolution de la chimie des eaux révèle la prépondérance du phénomène de dissolution des minéraux évaporitiques et la précipitation de la calcite comme principal mécanisme de contrôle de l’hydrochimie devant les phénomènes d’échange de base et par la pollution anthropique induit par la présence des nitrates. En conséquence il n’a pas été possible de déduire de l’hydrochimie des eaux les preuves d’une recharge par drainance ascendante depuis l’aquifère du Miocene vers les aquifères superficiels, bien que la similarité des faciès hydrochimiques tend à consolider l’hypothèse d’une origine unique des eaux, sans toutefois permettre une identification des chemins d’écoulement. / The study area lies in the northern part of central Tunisia and extends over about 650 km2. It is located betweenthe rainy Tellian region in the North and the Saharan region in the South. The Foussana Basin is a typical closedinland basin surrounded by high mountains where the precipitation varies over space and time as a result oftopography and seasonality.The main outcrop that marks the watershed of Foussana basin is the quaternary alluvium, which is surrounded byCretaceous reef of deposits covering folds Mountains bounding. The Foussana basin is composed of two aquifers,the PlioQuaternary and the Miocene aquifers. The PlioQuaternary aquifer consists of clayey sand, coarse sand andsandstone deposits. This aquifer is composed of two permeable levels PlioQuaternary Aquifer (PQ1) and PlioceneAquifer (PQ2), which are separated by interbedded sandy marl. The Miocene aquifer consists of sandstone andcoarse sands. This aquifer constitutes an important water source in the study area because of its relativelysignificant thickness and its water quality. It‘s separated to the PlioQuaternary aquifer by a clay layer. The differentaquifers communicate through faults.The groundwater flows occurs from the borders to the center of the basin,i.e. from the surrounding hills to the depression area. The main source of aquifer recharge is infiltration of rainfalland dam water.Groundwater samples with low TDS values, which typically correspond to outcrops of the Miocene aquifer andsome samples of the first PlioQuaternary aquifer PQ1, are typically of SO4-Ca-HCO3-Na water type. In contrast,groundwater samples with high TDS values, most of which were collected in the PlioQuaternary aquifer (PQ1 andPQ2) and groundwater of the Confined Miocene, are typically of SO4-Ca-Na-Mg water type. The main sources ofthe water mineralization in the Foussana basin are the water-rock interaction processes i.e. dissolution ofevaporates and cation-exchange process.The isotopic signatures permit to classify the studied groundwaters into different groups. The PlioQuaternaryaquifer groundwater was classified into two groups. These are the non-evaporated groundwater, which ischaracterized by depleted δ18O and δ2H contents highlighting the importance of modern recharge at higher altitude,and the mixing process with the deep aquifer of the Miocene. The evaporated groundwater that exhibits enrichedstable isotope contents, these enriched values could be related to the evaporation process, which occurs possiblyin the upper part of the unsaturated zone of the PlioQuaternary aquifer (depression area).The Miocene aquifersgroundwaters are classified into two groups. The first group is characterized by relatively depleted isotope contentscorresponding to outcropping Miocene in the border indicating the altitude effect. The second group isdistinguished by relatively depleted contents of stable isotopes corresponding to the confined Miocene reflectinga palaeoclimatic origin. Tritium data permit to identify recent groundwaters originating from a mixture ofcontemporaneous and post-nuclear recharge; and ancient groundwaters deriving from pre-nuclear recharge.Radiocarbon activities decrease from 80 pmc in the recharge area to less than 3 pmc in the confined aquiferproviding ages from present day to 30 000 years BP.In conclusion, a conceptual model has been produced to describe the functioning of the aquifers. The modelling isused as a tool to synthesise the data and the functioning hypothesis. It gives a visualization mean and can put inevidence the aspects, which should be deepened in next works.

Ce doctorat repose sur l'utilisation de Glycymeris glycymeris, un bivalve de la famille des Glycymerididae, pour reconstruire la variabilité environnementale en rade de Brest (France). Il vise à comparer des données géochimiques archivées dans ces coquilles avec diverses variables biologiques et écologiques. Les objectifs sont d'identifier de potentiels proxys et d'étendre notre connaissance de la variabilité environnementale avant les premières mesures instrumentales.Au total, 38 spécimens (vivants ou morts) ont été utilisés pour construire une chronologie s'étendant de 1891 à 2014.Les indices de croissance standardisés suggèrent que la croissance coquillière est principalement influencée par le débit de l'Elorn, la salinité et la matière particulaire en suspension.Des analyses isotopiques, réalisées sur les portions juvéniles de 24 spécimens, mettent en évidence que les variations de δ18Oaragonite enregistrent fidèlement la température de surface, permettant sa reconstruction sur 45 ans en rade de Brest. En terme de forçage climatique, ces variations de température en rade semblent contrôlées par le gyre subpolaire et l'East Atlantic Pattern.Cinq coquilles (3 d'âge inférieur à 10 ans et 2 âgées de 45 ans) ont ensuite été analysées pour leurs concentrations en strontium et magnésium par LA-ICP-MSLes concentrations en Mg et Sr, quant à elles, sont positivement corrélées à la température de l'eau à une échelle sub-annuelle, mais négativement à l'échelle annuelle.Cette étude met en lumière le potentiel de G. glycymeris comme archive de la variabilité climatique et environnementale en rade de Brest. Du fait du nombre important de spécimens sub-fossiles en rade, cette thèse fournit une base de travail pour l'extension de ces reconstructions dans un passé encore plus lointain. / This PhD thesis uses Glycymeris glycymeris, a temperate bivalve in the Glycymerididae family, to reconstruct environmental variability in the Bay of Brest, France. This work comprises of geochemical data archived within shells, compared with several biological and ecological variables. The aims of this study were to assess for potential proxies and expand environmental knowledge prior to local observational records.Thirty-eight live- and dead-collected specimens were used to create a chronology spanning 1891 to 2014. When the standardised growth index was correlated with local environmental factors, it showed that the predominant drivers of growth were Elorn inflow, salinity and suspended particulate matter.Isotopic analysis was undertaken on the juvenile increments of 24 shells. Our results highlight that variations in δ18Oaragonite accurately record local sea surface temperatures, leading to the creation of a 45-year SST reconstruction for the Bay of Brest. Correlations between this and climate forcings show that SSTs in this area are controlled by the subpolar gyre and the East Atlantic Pattern.Five shells (three under the age of 10 and two aged 45) were analysed using a LA-ICP-MS to determine the quantity of strontium and magnesium. Mg and Sr intensities are positively correlated with temperature sub-annually, but on an annual scale there is a negative correlation.This study conveys the potential of G. glycymeris as an archive of climatic and environmental variability in the Bay of Brest. As there are a large number of sub-fossil specimens in the area, this study also provides an anchored base for expansion further back in time.

Les estuaires sont des systèmes hautement dynamiques où interagissent des processus biogéochimiques complexes qui influent sur le devenir de la matière organique et non organique. La confrontation des eaux fluviales et marines induit des changements rapides des principaux facteurs structurant la distribution des organismes vivants et gouvernant la spéciation de certains éléments traces entre phase particulaire et dissoute, ex : gradient de salinité, teneurs en matières en suspension (MES). Ce travail vise à étudier l’estuaire de la Charente, principal fleuve influançant le bassin de Marennes-Oléron (première zone ostreicole française) afin (i) de caractériser la structure de la communauté zooplanctonique en relation avec les paramètres environnementaux, (ii) le fonctionnement de la base du réseau trophique de l’estuaire (identification des sources de matière organique exploitée par les organismes zooplanctoniques et suprabenthiques) et (iii) d’établir un état de contamination par les métaux des compartiments biotiques. L’estuaire de la Charente se distingue par des concentrations en MES extrêmement élevées, présentant néanmoins une contribution importante de la matière organique (efflorescence phytoplanctonique printanière en zone mésohaline et production microphytobenthique). La zone de turbidité maximale semble correspondre à un écotone qui contrôle les flux de matière organique et la distribution des organismes. Le mélange physique des particules issues des systèmes dulcicoles et marins adjacents à l’estuaire avec cette forte charge de matériel resuspendu conduit à une homogénéisation des signatures isotopiques et métalliques particulaires en été et automne le long du gradient de salinité. Les quatre assemblages zooplanctoniques identifiés sont structurés spatialement par la salinité et la concentration en MES et temporellement par les variations de température et de débit fluvial. Malgré la dominance quantitative du matériel détritique au sein du pool de matière organique particulaire (MOP), il semble que les 5 taxons planctoniques ou suprabenthiques dominants étudiés (Eurytemora affinis, Acartia spp., Daphnia spp., Neomysis integer, Mesopodopsis slabberi) présentent une sélectivité importante vis-à-vis de sources primaires distinctes. Cette succession spatio-temporelle d’espèces sélectives conduit à une multiplication des flux trophiques et semble ainsi optimiser à l’échelle annuelle l’exploitation de la MOP disponible. Les concentrations en Cd, Cu, Hg, Pb, V et Zn ont par ailleurs été mesurées dans près de 40 taxons estuariens (zooplancton, benthos, poissons). Malgré des concentrations en métaux dissous et particulaires plus faibles que dans les grands estuaires européens subissant une pression anthropique importante (Seine, Gironde), les niveaux de contamination mesurés dans les différents compartiments biotiques semblent globalement équivalents. Les évènements brefs (crue hivernale, efflorescence phytoplanctonique printanière) altèrent toutefois fortement ce schéma général en modifiant les sources primaires de matière organique disponibles et les concentrations métalliques particulaires (Cd notamment). / Estuaries are highly dynamic systems where complex biogeochemical greatly affect the fate of organic and non-organic matter. The physical mixing of freshwater and saltwater leads to high variability in the main drivers controlling organisms distribution and trace metals partitioning between the particulate and dissolved phases: eg. salinity gradient, suspended particulate matter concentration (SPM). This work aims thus at studying the Charente estuary, which is the main river discharging into the Marennes-Oléron Bay (first oyster producing area in France) in order to (i) characterize the zooplankton community structure and relate it to the main environmental parameters, (ii) identify the main organic matter sources contributing to the functioning of the planktonic food web and (iii) to characterize contamination of the biological compartment of this estuary. Although being one of the most turbid estuaries in Europe, the Charente estuary displays quite high organic matter contribution, especially through a spring phytoplankton bloom in the mesohaline area and microphytobenthic production. The maximum turbidity zone (MTZ) displays some ecotonal characteristics, controlling both organic matter fluxes and organisms distribution. The physical mixing of terrestrially and marine derived particles within the high load of resuspended estuarine particles leads to quite homogeneous isotopic and metallic signatures in particles all along the salinity gradient during summer and autumn. Salinity and SPM concentration significantly controls the spatial distribution of the four zooplankton assemblages identified while temperature and river discharge controls their temporal variations. Despite the quantitative dominance of terrestrially derived detrital organic matter, the five dominant planktonic and suprabenthic taxa studied (Eurytemora affinis, Acartia spp., Daphnia spp., Neomysis integer, Mesopodopsis slabberi) display strong selectivity toward different organic matter sources. At the annual scale, the exploitation of the available stock of organic matter seems optimized by this spatio-temporal succession of selective species that leads to multiple trophic pathways. In addition, the concentrations of Cd, Cu, Hg, Pb, V and Zn were measured in nearly 40 estuarine taxa (zooplankton, benthos, fishes). Although particulate and dissolved metal concentrations were somewhat low as compared to those measured in highly impacted European estuaries (Seine, Gironde), the contamination levels recorded in these biotic compartments were of the same order of magnitude. Moreover, brief events such as high water levels and phytoplankton blooms greatly affect this overall pattern by modifying the available organic matter sources and particulate trace metals concentrations (especially Cd).

Silicon (Si) is one of the most abundant elements in the dissolved phase in rivers and is a key nu-trient in riverine and marine ecosystems. The continental cycle of Si is complex and involves interactions with many secondary reservoirs such as clay minerals and biogenic silica (BSi), making the Si fluxes hard to constrain. Stable isotopes provide a way to trace and describe element cycling. The natural isotopic fractionations that accompany the transfer of the element from one reservoir to another lead to specific isotopic signatures that can be used to reconstruct its source and the pathway during its biogeochemical cycle. The aim of this thesis is therefore to explore the potential of Si isotopes as a tracer of the factors controlling the dissolved Si (DSi) concentration in rivers and more specifically in tropical rivers.<p>Key issues treated in this thesis are the improvement of our understanding of 1° the spatial and seasonal variability of Si isotopic signatures in rivers, 2° the biological influence on the riverine isotopic signatures and on DSi and BSi fluxes, and 3° the impact of the type of weathering on the riverine isotope signatures.<p>The isotopic composition of different tropical basins such as the Congo River (Central Africa), the Tana River (Kenya), the Amazon (South America) and its tributaries, were determined along with other physico-chemical parameters. In order to achieve this, the water sample purification processing, necessary before isotope analyses, required specific improvements that are also pre-sented here. The average of all the riverine δ30Si signatures available so far is +1.11 ‰ (n = 253). The impact of diatom growth on the isotopic signatures of the rivers can be clearly shown in the different systems studied, and especially in the Congo River where the isotopic signature could be used in order to estimate the diatom production. The impact of anthropic perturbations through dam construction is also clearly shown in the Tana River. On a global scale the biological influ-ence on the riverine isotopic signatures is estimated to induce an increase of 0.18 ‰ of the δ30Si signature in rivers. This study also confirms the preponderant influence of weathering and secondary clay formation on dissolved Si isotope signatures in the studied rivers. Finally, isotopic signatures from these rivers are compared to data available for other rivers around the world in order to draw large trends on a global scale. <p>/<p>Le silicium (Si) est l’un des éléments les plus abondants sous forme dissoute dans les rivières et est un nutriment fondamental tant dans les rivières que dans les écosystèmes marins. Le cycle continental du Si est complexe et inclut des interactions avec de nombreux réservoirs secondaires, comme les argiles et la silice biogénique (BSi), rendant les flux de Si difficiles à quantifier. Les isotopes stables fournissent un moyen de tracer et de décrire le cycle d’un élément. Le fractionnement isotopique qui accompagne le transfert de l’élément d’un réservoir à un autre induit des signatures isotopiques spécifiques qui peuvent être utilisées pour retracer la source et la trajectoire suivie par cet élément au cours de son cycle biogéochimique. Le but de cette thèse est d’explorer le potentiel des isotopes du Si en tant qu’indicateur des facteurs contrôlant la concentration en Si dissous (DSi) dans les rivières et plus spécifiquement dans les rivières tropicales.<p>Les questions principales traitées dans cette thèse sont l’amélioration des connaissances de :1° la variabilité spatiale et saisonnière des signatures isotopiques du Si dans les rivières, 2° l’influence biologique sur les signatures isotopiques des rivières et sur les flux de DSi et BSi et 3° l’impacte du type d’altération sur les signatures isotopiques des rivières. <p>Les compositions isotopiques de différents bassins tropicaux tels que le Fleuve Congo (Afrique Centrale), le Fleuve Tana (Kenya), l’Amazone (Amérique du Sud) et ses principaux affluents ont été déterminées en même temps que d’autres paramètres physicochimiques. Pour ce faire, le pro-cédé de purification des échantillons d’eau, préalable aux analyses isotopiques, a nécessité des améliorations spécifiques qui sont également présentées ici. La moyenne de toutes les signatures δ30Si accessibles à l’heure actuelle est de +1.11 ‰ (n = 253). L’impact de la croissance des diatomées sur les signatures isotopiques des rivières est démontré dans les différents systèmes étudiés, spécialement pour le Fleuve Congo où la signature isotopique a pu être utilisée afin de déterminer la production de diatomées. L’influence de perturbations anthropiques telles que la construction de barrages a pu être démontrée pour le Fleuve Tana. À l’échelle globale, on estime que l’influence biologique sur la signature isotopique des rivières mène à une augmentation de 0.18 ‰ de la signature δ30Si moyenne des rivières. Cette étude confirme également l’influence prépondérante de l’altération et de la formation d’argiles secondaires sur les signatures isotopiques du DSi dans les rivières étudiées. Enfin, les signatures isotopiques de ces rivières sont comparées aux données accessibles pour d’autres rivières à travers le monde afin d’en déduire les grandes tendance à l’échelle mondiale.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The combined methods of stomach content analysis and stable 15N and 13C isotope biochemistry analysis were used to investigate the trophic dynamics and feeding ecology of coastal pelagic fishes in the waters off southeastern Florida, USA. The coastal pelagic fish complex includes blackfin tuna Thunnus atlanticus, dolphinfish Coryphaena hippurus, king mackerel Scomberomorus cavalla, little tunny Euthynnus alletteratus, skipjack tuna Katsuwonus pelamis, and wahoo Acanthocybium solandri. These coastal teleosts, particularly the tunas and wahoo, are primarily targeted by recreational anglers. However, there is a shortage of available trophic and diet composition data concerning these fishes of the coastal pelagic ecosystem. Stomach and muscle tissue samples were collected from the species of various lengths over a three-year period from March 2010 and March 2013. Across all six species, teleost fishes dominated the prey with an average 64.5% by occurrence, 63.7% by number, and 89.9% by weight. There were two dominant prey families: Clupeidae and Carangidae. Dolphinfish showed the lowest diet overlap among the six species, due to the highly diverse diet. The highest diet overlap occurred between king mackerel and little tunny. The mean δ15N ranged from 8.21 ‰ (wahoo) to 13.18 ‰ (king mackerel), and the mean δ13C ranged from -18.41 ‰ (king mackerel) to -16.70 ‰ (dolphinfish). Blackfin tuna exhibited the largest δ15N range (7.22 to 13.21 ‰), as well as the largest δ13C range (-19.13 to -12.99 ‰). The δ15N and δ13C signatures in the muscle tissue showed evidence of shifts to higher trophic levels with an increase in fish size and the formation of distinct trophic groups among the coastal pelagic predators. The δ13C also suggested an inshore-offshore spatial relationship among the coastal pelagic fish. The trophic dynamics and feeding ecology data generated by this study will provide valuable baseline data for the coastal pelagic complex and future ecosystem studies.

La présence d’arbres en milieu urbain, où vit plus de la moitié de la population mondiale, participe à l’amélioration de la qualité́ de vie des citadins par les services écosystémiques qu’ils nous rendent. Cependant, de nombreuses études ont mis en évidence l’importante mortalité́ et la faible espérance de vie des arbres en ville du fait des stress hydriques. Nos résultats dendroclimatiques ont pu montrer qu’en comparaison avec les arbres de parc urbain ou d’arboretum, les arbres de rue ont généralement une croissance plus faible. Les précipitations en automne et au printemps semblent jouer un rôle prépondérant pour la croissance annuelle des tilleuls argentés urbains. Nos résultats sur le niveau des réserves (lipides et glucides) montrent que les arbres en condition de stress hydrique pourraient activement réguler leurs réserves de C selon une stratégie de survie à long terme. Les jeunes tilleuls argentés, quant à eux, semblent privilégier l’allocation du C dans la croissance radiale. Nos résultats sur la signature isotopique en 18O et en 2H des sources d’eau en ville, indiquent enfin que les arbres en rue semblent dépendre principalement de l'eau du sol très superficiel (couche 0-20 cm). Cette eau est un mélange d'eau de pluie et d'eau non potable plus ou moins évaporées, bien que ces arbres ne soient soumis à aucune stratégie d'irrigation particulière à Paris. Les arbres les plus matures en rue semblent disposer d’une plus faible disponibilité́ en eau due à la plus forte évaporation des sols en surface. En conclusion, cette étude appelle à (i) la protection des sols nus d’une évaporation excessive, et (ii) une irrigation en harmonie avec la phénologie. / The presence of trees in urban areas, where more than half of the world's population lives, contributes to improving the quality of city through ecosystem services they provide. However, many studies have shown that urban trees face high mortality rates and low life expectancy due to water stress. Dendroclimatic results have showed that, in comparison with the urban park or arboretum trees, street trees generally have lower annual growth rate. Precipitation in autumn and spring seem to play the main role in the annual growth of urban silver lindens. Reserve measurements (lipids and carbohydrates) show that trees under water stress could priorize C reserves as a long-term survival strategy. On the contrary, younger silver lindens seem to favor the allocation of C in the radial growth. Our results on the isotope signature in 18O and 2H of water sources in the city, indicated that street trees seem to depend mainly on soil water in upper layers (0-20 cm layer). This water is a mixture, more or less evaporated, from precipitation and non potable water, although street trees are not subject to any particular irrigation strategy in Paris. Larger street trees seem to have lower water availability due to increase of surface soils evaporation. To conclude, This study would rethink current irrigation strategies in the city, focusing on (i) the protection of bare soil from excessive evaporation, and (ii) an irrigation in harmony with the phenology of species.

Philosophiae Doctor - PhD / The analysis of geologic, hydrologic and hydrogeologic data interpreted to give the characteristics of the Cape Flats aquifer showed the quality of groundwater from the aquifer is suitable for development as a water resource. The conceptual model of the Cape Flats sand shows an unconfined sandy aquifer, grading into semi-confined conditions in some places where thick lenses of clay and peat exists. Recharge rates through the saturated zone of the Cape Flats aquifer have been determined by water table fluctuation (WTF), rainfall-recharge relationship, soil water balance and chloride mass balance methods (CMB). Recharge rates using the WTF vary considerably between wet and dry years and between locations, with a range of 17.3% to 47.5%. Values obtained from empirical rainfall-recharge equation (method 2) agree with those of the WTF. Recharge estimates from the water balance model are comparatively lower but are within the range calculated using empirical method 2 (i.e. 87 - 194 mm or 4 &ndash; 21% of MAP). These recharge rates also agree with estimates from the series of other methods applied to sites located in the north-western coast of Western Cape and are comparable to recharge rates obtained elsewhere in the world. / South Africa

The feeding ecology of a common saltmarsh crab, Armases cinereum (Armases), was investigated to determine how habitat (mangrove vs. ecotone, natural mangrove vs. modified mangrove fringe) influenced this species’ feeding behavior and trophic ecology in its southwestern Florida, USA, distribution. In the laboratory, Armases’ preference for mangrove material was examined using leaves of three mangrove species (Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle) and leaves of different degradation levels (fresh, senescent, and partially-decomposed). Leaf material from A. germinans was preferentially consumed over the other taxa at fresh and partially-decomposed levels of leaf decay. When Armases were offered a choice between four common upland vegetation types (Iva frutescens, Borrichia frutescens, Nephrolepis biserrata, and Stenotaphrum secundatum), the preferred mangrove from the previous experiment (A. germinans, partially-decomposed), and an animal prey item (Gryllodes sigillatus, cricket), Armases displayed greatest selectivity for the animal prey item and high selectivity for both I. frutescens and A. germinans plant taxa (Manly-Chesson α selectivity and Chesson ϵ electivity). Field-based stable isotope analysis was used to determine trophic position and reconstruct dietary proportions of Armases across three pairs of natural and heavily-modified sites within Tampa Bay to determine whether Armases feeding behavior is impacted by the presence of upland forest adjacent to mangrove forest habitat. Analysis of trophic position based on δ15N signatures of Armases from each of the six populations revealed that Armases in habitats with modified connectivity had lower trophic variability and significantly higher average trophic position compared to Armases sampled from the three sites with natural connectivity. Stable isotope diet reconstruction using the Bayesian mixing model SIMMR further established Armases preference for animal-derived food material in habitats with natural and modified connectivity. This preference is likely driven by high selectivity for sources rich in Nitrogen (i.e., animal tissue, partially-decomposed A. germinans material, and I. frutescens). I determined that the use of laboratory experiments in conjunction with stable isotope mixing models is important in accurately investigating feeding preferences of Armases in mangrove intertidal regions. Together, my results show that the diet of Armases is broadly omnivorous and populations can be influenced by the heterogeneity of their habitat. Further feeding experiments, dietary analyses and a longer sampling period are needed to more definitively identify the patterns of Armases detritivory in mangrove and ecotonal upland habitats.

Abstract This dissertation is a pioneering effort in a project to document, preserve and study the human remains found beneath old Northern Finnish churches. These remains have spontaneously mummified as a result of the early modern elite’s practice of burying under church floors. The main subject of the study is an early 17th-century Vicar of the Kemi parish, Nikolaus Rungius, and his mummified remains. His mummy that still is an important tourist attraction and a popular character in local lore, has a unique history as it has been exhibited since the 18th-century. The computed tomography scanning performed on the mummy revealed pathological findings suggesting that the Vicar suffered from obesity-related conditions. The most convincing of these was the manifestation of DISH in his thoracic spine. There were also indications of tuberculosis, such as a probable Pott’s spine, as well as calcifications, for example, in subareolar regions. The latter may also represent gynaecomastia, which currently is a rather common finding in elderly men. The scans also provided information concerning the preservation. In addition to the right forearm that was lost by the mid-19th-century, six cervical vertebrae are missing. The head still appears to be attached through a continuous band of soft tissue, and has likely belonged to the same person as the rest of the body. Both the Vicar’s dental health examined through the scans, and the results of the stable isotope analyses (&#948;13C, &#948;15N) of his nail keratin, along with the obesity-related findings, indicated a rather heavy diet rich in protein. This is in line with what is known about the early modern Northern Finnish diets. They were mainly based on foodstuffs acquired by hunting, fishing and animal husbandry. These interpretations also comport with the Vicar’s status, and assumed wealth. Typically, the clergy could maintain abundant diets. Even manifestations of DISH are rather commonly found in remains from monastery sites. The Vicar’s &#948;15N value was elevated in comparison to the values of the control group comprised of other early modern human remains in Northern Finnish churches. This discrepancy may be due to a stronger input of dietary protein sourced from top aquatic predators, such as the seal. Another plausible explanation could be the connection between the elevated &#948;15N value and DISH previously found by several authors. / Tiivistelmä Tämä väitöstutkimus on osa projektia, jonka päämääränä on vanhojen pohjoissuomalaisten kirkkojen alla lepäävien muumioituneiden vainajien dokumentointi, säilyttäminen ja tutkimus. Muumioitumisen taustalla on varhaisen uuden ajan eliitin tapa haudata kirkkojen lattioidenalaisiin tiloihin. Tutkimuksen pääkohteena on 1600-luvun alun Kemin seurakunnan kirkkoherran, Nikolaus Rungiuksen hyvin säilynyt ruumis. Kirkkoherran muumiolla on ainutlaatuinen historia, sillä se on ollut nähtävillä 1700-luvulta lähtien. Tämä paikallistaruston hyvin tuntema hahmo on edelleenkin tärkeä turistikohde. Muumion tietokonetomografinen kuvantaminen paljasti useita patologisia löydöksiä. Osa niistä vihjaa kirkkoherran kärsineen tiloista, joilla on yhteys ylipainoon. Kaikista vakuuttavimmin siihen viittaisi hänen rintarangassaan havaittu diffuusin idiopaattisen skeletaalisen hyperostoosin (DISH) aiheuttama leesio. Myös tuberkuloosista havaittiin viitteitä, kuten mahdollinen Pottin tauti, sekä subareolaariset kalkkeumat. Jälkimmäiset voivat tosin olla gynekomastiankin aiheuttamat. Kuvantaminen tarjosi tietoa myös muumion säilyneisyydestä. Pitkään kadoksissa olleen oikean kyynärvarren lisäksi kuusi kaulanikamaa puuttuivat. Pää ja torso näyttäisivät kuitenkin edelleen yhdistyvän toisiinsa niskassa, mikä tarkoittaisi molempien osien kuuluneen samalle yksilölle. Sekä kirkkoherran hammasterveys, että kynnen keratiinin isotooppianalyysit (&#948;15N, &#948;13C) indikoivat, että hänen ruokavalionsa lienee ollut raskas ja proteiinirikas. Rintarangan DISH-leesio tukee tätä päätelmää, joka sopii yhteen myös aiempien pohjoissuomalaista varhaisen uudenajan ruokavaliota koskevien tietojen kanssa. Ravinto hankittiin lähinnä metsästämällä, kalastamalla ja karjanhoidolla. Tulokset yhtenevät kirkkoherran sosiaalisen statuksen ja oletetun vaurauden kanssa: papisto kykeni tyypillisesti nauttimaan runsaasta ruokavaliosta. Jopa ylipainoon yhdistetty DISH on erityisen tyypillinen löydös nimenomaan luostarikaivauksien vainajissa. Stabiili-isotooppianalyysit paljastivat kirkkoherran typpiarvon merkittävästi muista pohjoissuomalaisista muumioista koostuvan verrokkiaineiston arvoja korkeammaksi. Ero selittynee ravinnon suuremmalla määrällä vesistöjen huippusaalistajien, kuten hylkeiden proteiinia. Toinen mahdollinen selitys voi liittyä kohonneiden typpiarvojen ja DISHin väliltä aiemmin löydettyyn yhteyteen.