The response of Mediterranean coralligenous assemblages to climate change: an integrated, long-term view from species and populations to the ecosystem level

[eng] Climate change has emerged as one of the greatest and most pervasive threats that our natural heritage will have to face in the coming decades. Together with other anthropogenic pressures such as pollution, overfishing or habitat degradation, climate change is causing enormous impacts on oceans, affecting all kind of marine communities and driving major losses to biodiversity. In this framework of global change, the Mediterranean Sea, which has been identified as one of the major hotspots of marine biodiversity, has also become a hotspot of climate change. Consequently, some of its most emblematic and ecologically important communities are now under threat. This is the case of the coralligenous assemblages, which are temperate benthic communities which stand out for their great structural complexity and exceptional biodiversity (they harbour approximately 10% of Mediterranean species). Most of the constituent species of these communities exhibit high longevity and slow population dynamics. Consequently, they are especially vulnerable to disturbances that increase adults mortality. In fact, thermal anomalies linked to ocean warming have impacted the coralligenous assemblages in several ways during last decades, triggering changes that go from the observed mass mortalities of benthic organisms to potential changes at the community and ecosystem levels. However, despite the increasing interest of the scientific community to conserve the coralligenous, how these benthic communities are responding to climate change at the community level is poorly understood. In this thesis, we have taken this leap by integrating responses from species to the ecosystem level, through populations and communities. In particular, we have combined field observations of ecological and environmental changes, aquaria experiments, ecological theory, and cutting-edge quantitative research to improve our understanding of the bio-ecological consequences of ocean warming for Mediterranean coralligenous assemblages. In the first three chapters, we gathered field and experimental data on sensitivity of several coralligenous species and populations to marine heatwaves (MHWs) by conducting a literature review on previous mass mortality events occurred in the Mediterranean and by carrying out scaled-up thermotolerance experiments. The results of Chapter 1 revealed contrasting patterns of sensitivity to MHWs among different coralligenous species and populations. The posterior multi-specific thermotolerance experiment (including corals, sponges and tunicates) conducted in Chapter 2 confirmed the high response diversity to warming among co-occurring species observed in the field. These results demonstrate that co-occurring species that are taxonomically and morpho- functionally similar can have contrasting thermotolerances. Moreover, the observed patterns suggest that coralligenous assemblages could have certain degree of insurance against MHWs, since the decline of sensitive species could potentially be compensated by other functionally similar species that are more resistant. The results of the multi- population thermal experiment conducted in Chapter 3 with 12 populations of the red gorgonian Paramuricea clavata (Risso, 1826) revealed that this species, which has a key habitat-forming role in coralligenous assemblages, is highly sensitive to thermal stress across its distributional range. Moreover, we found little local adaptation to average thermal regime and little acclimatization to local above-average warm temperatures prior to the experiment. These findings, which were obtained at a spatial scale never addressed before (> 2000 km) for P. clavata, question the adaptive potential of this species to climate change. In Chapter 4, we further explored the vulnerability of Mediterranean habitat- forming octocorals to climate change by exploring the long-term recovery capacity of Corallium rubrum (Linnaeus, 1758) and P. clavata from recurrent MHWs. We explored the long-term trajectories (15 years) of different populations that were firstly impacted by the 2003-MHW in terms of changes in biomass, density and size structure. We found that all impacted populations have followed collapse trajectories. These results further highlight the high vulnerability of these species to the ongoing climate change. Finally, we took the leap from species and populations to the community and ecosystem levels in Chapter 5, to explore if MHWs have driven changes in the functional community structure of coralligenous assemblages, which could imply changes for ecosystem functioning. Specifically, we conducted a multi-taxa, trait-based analysis and found that MHW are shifting the functional identity of coralligenous assemblages (i.e., dominant functional traits). Interestingly, the observed changes were driven primarily by the decline of a single functional group (habitat-forming octocorals), whose species are functionally unique. Consequently, by severely affecting habitat-forming octocorals, MHWs are leading to assemblages that are deficient in key functional traits, likely causing changes in ecosystem functioning. Overall, this thesis provides an integrated, long-term view of the interconnected responses to ocean warming found in coralligenous assemblages. The combined results of this thesis suggest that despite structural changes induced by climate change, most ecosystem functions count on certain degree of insurance against MHWs. However, some essential functions (e.g., 3D-habitat provision) could be highly compromised or even totally disappear, threatening the overall assemblage stability. Given the current climate change trends, identifying and preserving the mechanisms that maintain essential ecosystem functions and the overall ecosystem stability is critical. In this thesis, we have identified the general loss of arborescent octocorals as the greatest disruptive process for coralligenous assemblages. Therefore, the future trajectories of these emblematic Mediterranean communities will greatly depend on the design and implementation of measures that favour the conservation and adaptive management of these key habitat-forming species in the face of climate change

Procedencia y modelo diagenético de las areniscas de Facies Utrillas en la cordillera Ibérica (Umbral de Ateca) y la meseta norcastellana

Las facies Utrillas de la Cordillera Ibérica, en los alrededores del Umbral de Ateca y en la Meseta norcastellana, provincia de Soria, son un depósito detrítico formado en un ambiente sedimentario de sistemas aluviales que se puede subdividir en dos unidades (Meléndez y Vilas, 1980): la inferior, compuesta por canales y barras de litología conglomerática y areniscos a, se caracteriza por haberse depositado en un medio aluvial de tipo trenzado; y la superior, integrada porlutitas con cuerpos intercalados de areniscas canaliformes originada en un medio fluvial mucho más maduro. Las areniscas de las facies Utrillas son fundamentalmente arcosas y subarcosas, con bajos contenidos en fragmentos de roca y una matriz de tipo silcreta debida a procesos edáficos. La presencia del feldespato-K es el factor determinante de los procesos diagenéticos más importantes sufridos por estas areniscas; aparición de epimatriz de caolinita-ilita, pore filling de caolinita, cierre de la porosidad primaria y generación de porosidad secundaria por disolución de dichos feldespatos. Otros procesos diagenéticos menos significativos y más localizados hacia el techo de las series, lo constituyen: cementos de calcita, dolomita y anhidrita, así como clay coats de esmectita e interestratificados ilita-esmectita. Las areniscas estudiadas muestran un claro ejemplo de procedencia mixta de áreas fuentes compuestas por rocas metamórficas de alto, medio y bajo grado (gneises, esquistos y pizarras), no presentando indicios de aportes procedentes del macizo granítico de Guadarrama. En el Umbral de Ateca yen la unidad inferior, además, se pone de manifiesto la procedencia a partir de rocas sedimentarias areniscosas y pelíticas. La secuencia diagenética encontrada, con un modelo típico de flujos meteóricos, la escasa compactación química y los valores de la Ro = 0,5 nos ha permitido deducir para ellas una etapa de mesodiagénesis semimadura, según los criterios de Schmidt y McDonald (1979)

Relaciones entre el ambiente de sedimentación y los procesos diagenéticos en las areniscas del Buntsandstein del Umbral de Ateca (Cordillera Ibérica).

Los sedimentos de facies Buntsandstein del Umbral de Ateca se depositaron en un medio de transición, en áreas intra y supramareales, dentro de un sistema deltaico dominado por procesos de "crevassing". En base a los datos de campo y también a parte de los petrológicos cabe, además, la interpretación, menos probable, de que el medio sedimentario fuera lacustre salobre y esporádicamente evaporítico, donde la sedimentación se realizará, fundamentalmente, a partir de flujos gravitatorios de elevada densidad. Los cuerpos arenosos son arcosas y subarcosas ricas en materia orgánica presentando, asociadas a la misma, una serie de concreciones (microgeodas) originadas posiblemente por acción bacteriana y de hongos. También son frecuentes las rizocreciones y otras marcas de carácter edáfico. Los cementos más significativos y abundantes y su secuencia de formación serían: óxidos de Fe y Mn, calcita, feldespato potásico, siderita, calcita ferrosa, anhidrita, dolomita, baritina, calcita y caolinita. Este tipo de secuencia de cementación no se parece a la encontrada en los sedimentos del Buntsandstein de áreas próximas en la Cordillera Ibérica y es bastante similar al encontrado por CASTELLTORT et al. (1987). en las areniscas de facies evaporíticas (sabkha costera), del Muschelkalk Medio de los Catalánides. Este hecho nos confirma la idea que por datos sedimentológicos de campo se había deducido, respecto a su ambiente de sedimentación y a su posible equivalencia lateral con el Muschelkalk Inferior y Medio de la Cordillera Ibérica en su extremo oriental y de los Catalánides. De la tipología de los granos de cuarzo y de la composición de las areniscas se deduce que las áreas fuentes eran los gneises del Macizo Hespérico, al igual que para el Buntsandstein de áreas próximas (ARRIBAS et al., 1985), con influencia menos marcada de áreas metamórficas de bajo grado, al menos en los sedimentos arenosos

Study of the lateral pass width for conventional and ultrasonic vibrations-assisted ball burnishing on Ti-6Al-4V specimens

Ball burnishing is a technological finishing process based on plastic deformation of the objective surface by means of a hard ball gliding over it. Along with its easiness of application, possible on the same machine where machining was performed [1], burnishing is a comprehensive process able to achieve surface roughness improvements, and compressive residual stresses up to deep layers of the material [2]. Burnishing results have proved to be depending of a proper selection of parameters, which must be correctly controlled during the process. That is the case of burnishing force or the number of passes [3]. Among these parameters, the lateral pass width has proved to be influential on the surface roughness results, due to the behavior that most materials show when being plastically deformed. In effect, the applied force makes the material to flow to the borders of the burnishing imprint, giving way to a pile-up effect. This paper deals with indentation experiments on Ti-6Al-4V to deepen in the burnishing process of this material. Single burnishing imprints are geometrically characterized combining different levels of force, number of passes, and comparing the conventional process with that assisted with vibrations. An optimal lateral pass width is thus determined, and technological recommendations are made for future applications of the process.Peer ReviewedPostprint (author's final draft

Sedimentología del mioceno de la ciudad autónoma de Melilla

En este trabajo se describen la estratigrafía y las facies de los materiales miocenos del territorio de la Ciudad Autónoma de Melilla y se realiza una correlación con las diferentes unidades cronoestratigráficas descritas en la cuenca que permite asignar una edad más precisa a estos materiales. Se definen tres nuevas unidades estratigráficas. La unidad carbonática inferior consta de dos subunidades. La subunidad inferior arrecifal está formada casi exclusivamente por colonias de corales de tipo Porites ( boundstones ), con facies bien desarrolladas de núcleo y talud arrecifal. Estas facies arrecifales son muy similares a las descritas en los arrecifes coralinos típicos del Messiniense. Adaptándose a las bioconstrucciones arrecifales se dispone una subunidad carbonática bioclástica compuesta principalmente por calizas ( grainstones-packstones ) de moluscos y algas rojas. La estratificación de esta subunidad exhibe diferentes grupos de clinoformas que indican una progradación hacia el O de esta plataforma bioclástica. Por encima se dispone la unidad detrítica intermedia, que está constituida por areniscas y limos de color amarillo depositados en un ambiente deltaico progradante que rellena la paleotopografía dejada por la unidad subyacente. La unidad carbonática superior se dispone sobre las dos anteriores y está constituida por capas de calizas oolíticas ( packstones/ grainstones ) y por niveles estromatolíticos ( boundstones ) depositados en un ambiente de plataforma somera. Hacia el SO, la serie miocena pasa lateralmente a los sedimentos volcanoclásticos pertenecientes al cercano complejo volcánico del Gourougou. La similitud entre las facies de las tres unidades estratigráficas definidas en este trabajo y las de las unidades cronoestratigráficas descritas en la Cuenca de Melilla permite asignar una edad Messiniense para toda la serie terciaria del territorio de Melilla.Peer ReviewedPostprint (published version

Ciments de calcita : anàlisi de tres zones de Catalunya

Investigadors del Departament de Geologia de la UAB, en col·laboració amb investigadors d'altres centres europeus, han dut a terme una anàlisi química sobre el ciment de calcita, un dels més habituals a les roques sedimentàries detrítiques (composades per fragments), en tres zones diferents de Catalunya.Investigadores del Departament de Geologia de la UAB, en colaboracióncon investigadores de otros centros europeos, han llevado a cabo unanálisis químico sobre el cemento de calcita, uno de los más habitualesen las rocas sedimentarias detríticas -compuestas por fragmentos-, entres zonas diferentes de Cataluñ

A generic persistence model for CLP systems (and two useful implementations)

This paper describes a model of persistence in (C)LP languages and two different and practically very useful ways to implement this model in current systems. The fundamental idea is that persistence is a characteristic of certain dynamic predicates (Le., those which encapsulate state). The main effect of declaring a predicate persistent is that the dynamic changes made to such predicates persist from one execution to the next one. After proposing a syntax for declaring persistent predicates, a simple, file-based implementation of the concept is presented and some examples shown. An additional implementation is presented which stores persistent predicates in an external datábase. The abstraction of the concept of persistence from its implementation allows developing applications which can store their persistent predicates alternatively in files or databases with only a few simple changes to a declaration stating the location and modality used for persistent storage. The paper presents the model, the implementation approach in both the cases of using files and relational databases, a number of optimizations of the process (using information obtained from static global analysis and goal clustering), and performance results from an implementation of these ideas

Comparison of thermal performance of 3D printer liquefiers through finite element models

Open source 3D printers have experienced an intense expansion during the last years, mainly because of their accessibility and the vast availability of information thanks to user communities. This fact presents researchers with a perfect context for hardware innovation, by improving the overall printing process, also in terms of durability of the printing machine. A 3D printer liquefier must transmit heat to the thermoplastic material in order to extrude it, reaching temperatures above 200 degrees for some materials like ABS on the tip of the nozzle. The design of the heating process must comply with keeping the balance between proper heating of the material and controlling the temperature along the extruding body, so that the printer itself is not harmed for overtemperature. On the other hand, the design must guarantee that the melting front is located in an intermediate point between the nozzle tip and the entrance of the raw material, to minimize pressure drops in the system, and so decreasing the demanding energy to the feeding motors. An alternative design of the heating system, Twist3D, is proposed in this paper.Peer ReviewedPostprint (published version

Sedimentología de la unidad superior de la Formación Fortuna (Mioceno inferior) en el NE de Túnez

La Formación Fortuna (Oligoceno superior-Mioceno inferior) aflora ampliamente en Túnez y está constituida por tres unidades de carácter detrítico. Las dos inferiores se sedimentaron en un ambiente deltaico-lagunar mientras que la unidad superior es fluvial. Este trabajo se centra en la unidad superior de la Formación Fortuna (Aquitaniense-Burdigaliense), que en el noreste de Túnez posee una potencia de 130 m y está constituida por areniscas de tamaño fino a muy grueso con cantos dispersos de cuarzo. Los estratos, de potencias entre 0,5 y 4 m, muestran laminaciones cruzadas, que indican un transporte hacia el NE y E, paralelo a las direcciones estructurales del Atlas tunecino. En estos materiales dominan las facies de canales y de llanuras arenosas propias de un ambiente de sedimentación fluvial arenoso trenzado. Las areniscas de la unidad superior de la Formación Fortuna son cuarzoarenitas, muy maduras texturalmente, con algunos fragmentos de rocas y feldespatos. El área fuente estaba localizada en la plataforma sahariana al SO de Túnez, dada la presencia de fragmentos de areniscas cementadas por cuarzo (procedentes de las areniscas paleozoicas del Tassilis o de las areniscas cretácicas del "continental intercalaire" o de las areniscas eocenas) y de fragmentos de rocas plutónicas y metamórficas (procedentes del macizo de Hoggar). El reciclaje de las litologías sedimentarias junto con el transporte fluvial permite explicar el alto contenido en cuarzo. Pero la extrema madurez indica que las litologías del área fuente estaban afectadas por un manto de alteración que o bien era erosionado por la red fluvial miocena o bien era reciclado a través de las formaciones sedimentarias premiocenas.The Fortuna Formation (Upper Oligocene-Lower Miocene) crops out widely in Tunisia and is composed by detrital rocks arranged in three units. The lower and middle units were deposited in deltaic-lagoonal environment, while the upper unit was deposited in fluvial environment. The upper unit of the Fortuna Formation (Aquitanian-Burdigalian) in northeast Tunisia, the subject of the present study, is 130 m thick and mostly made up of fine to very coarse sandstones with disperse quartz pebbles and containing tree stems. The section is arranged in 0.5 to 4 m thick beds with abundant cross-laminations indicating E and NE directed paleocurrents (parallel to main structural trend of the Tunisian Atlas). The presence of channel and sand-flat facies indicates that sedimentation took place in a fluvial braided environment. Petrologically, sandstones of the upper unit of the Fortuna Formation are texturally mature quartz-arenites with scarce rock fragments and feldspars. The source area was located to the SW (Sahara Platform). This fact is supported by the presence of quartz-cemented arenite clasts (Palaeozoic Tassilis sandstone, Cretaceous "continental intercalaire" and Eocene sandstone) and plutonic and metamorphic rock fragments (Hoggar basement massif) in the Sahara Platform. Recycling of ancient sedimentary formations is an important process to account for high quartz-grain content (occasionally with inherited overgrowths). Also contributing to this mature composition, the source area was probably affected by an alteration mantle that could made have been primarily eroded by the Miocene Fortuna fluvial network or, alternatively, recycled from older detrital formations