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[eng] The returning limb of Atlantic Meridional Overturning Circulation (AMOC) is partly supplied by the cold-fresh waters that enter through the Drake Passage. Up to the isoneutral 28.0 kg m−3, the mean water inflow through the Drake Passage to the Scotia Sea is 140.8 ± 7.4 Sv and the outflow through the Northern Passages is 115.9 ± 8.3 Sv. Below this isoneutral reference and down to 2000 m, an additional 23.4 Sv enters through the Drake Passage. The mean barotropic contribution always represents over half the total transports, with substantial seasonal and moderate interannual variability in the water transports. The water mean-residence time is about 6 - 8 months. Combining the Argo floats data with other observational measurements, we apply a climatological high-resolution inverse model over the Scotia Sea boundaries up to the 28.0 kg m-3 isoneutral. The ACC enters 136.7 ± 1.0 Sv through the Drake Passage and exits 137.9 ± 1.0 Sv through the northern boundary, with the difference responding to the South Scotia Ridge and Philip Passages contributions. Along its northward path, the ACC waters lose heat but gain equatorward freshwater transport. Within the Scotia Sea, the surface-modal and modal-intermediate waters experience production in all biogeochemical variables. Finally, regarding anthropogenic DIC, the Scotia Sea stores 0.123 Pg C yr-1. Then, the ROD method compares actual drifters' displacements with numerical trajectory predictions; the observed-predicted differences in final positions respond to diffusive motions not captured by the numerical models. The ROD method is applied in the western South Atlantic Ocean leading to maximum diffusivities of 4630 - 4980 m2 s-1 in the upper 200 m of the water column, presenting an inverse relationship with depth. The diffusivities near the surface are fairly constant in latitude but the diffusion coefficients at 1000 m decrease considerably south of the Southern Boundary. With the horizontal diffusion coefficients obtained previously, we use the Lagrangian technique to determine the fraction of the upper-ocean transport that remains in the ACC flow as it crosses the South Atlantic Ocean and the fraction that contributes to the South Atlantic subtropical gyre. The mean results reveal that 94.8 Sv remains in the ACC, whereas a total of 15.1 Sv contributes directly to the AMOC. This AMOC transport takes a median of 14.3 years to arrive to the Brazilian Current from the Drake Passage. Furthermore, 78.1% of the particles that recirculate in the subtropical gyre perform one recirculation. The results confirm that the water masses entering the subtropical gyre through its eastern edge warm up substantially and lose density, partly transformed to surface waters. Furthermore, the contributions at the eastern edge of the South Atlantic subtropical gyre from the warm-water and the cold-water routes are compared. We perform numerical simulations of Lagrangian trajectories to identify the multiple direct and indirect pathways of intermediate waters. The total cold-route contribution represents between 17.9 and 18.9%, substantially higher than the 7.1 to 12.3% warm- route contribution. Several individual pathways form both routes, but the direct path is the preferential pathway followed by 83.6 to 87.2% of the water parcels. The direct cold route is the one that undergoes a greater transformation of its water masses, and it is confirmed that also feeds the Agulhas Current, contributing similarly to that coming from the Indonesian Throughflow., [cat] La branca de retorn de la circulació meridional de l'Atlàntic (AMOC) és parcialment sustentada per les aigües fredes i fresques que procedeixen de l'oceà Pacífic a través del passatge de Drake. Fins a la isoneutra de 28.0 kg m-3, l'entrada d'aigua mitja a través del pas de Drake cap al mar de Scotia és de 140.8 ± 7.4 Sv mentre que la sortida a través dels passos del Nord correspon a 115.9 ± 8.3 Sv. La seva component barotròpica mitjana sempre representa més de la meitat dels transports totals, amb una variació interanual moderada i estacional considerable en els transports d'aigua. El temps mig estimat de residència en el mar de Scotia és d'uns 6 - 8 mesos. Combinant les dades de boies Argo amb altres mesures observacionals, s’ha aplicat un model invers climatològic en els límits de el mar de Scotia amb la finalitat de definir el flux d'entrada i sortida de la ACC fins a la isoneutra de 28.0 kg m-3. Exactament, 136.7 ± 1.0 Sv del ACC entren pel pas de Drake i surten 137.9 ± 1.0 Sv pel límit nord. Al llarg de la seva trajectòria cap al nord, les aigües del ACC perden calor però guanyen transport d'aigua dolça. Dins del mar de Scotia, les aigües superficials-modals i les superficials-intermèdies experimenten producció en totes les variables biogeoquímiques. Finalment, en quant al DIC antropogènic, el mar de Scotia emmagatzema 0.123 Pg C any-1. Després, el mètode ROD compara els desplaçaments reals dels derivadors amb les trajectòries de les partícules simulades amb els models numèrics; les diferències observades-predites en les posicions finals responen a moviments difusius no capturats pels models numèrics. El mètode ROD és aplicat a l'Atlàntic Sud occidental obtenint difusions màximes de 4630 - 4980 m² s-1 en els primers 200 m de la columna d'aigua, presentant una relació inversa amb la profunditat. Prop de la superfície, els coeficients de difusió són bastant constants en latitud, no obstant això a 1000 m els coeficients disminueixen considerablement al sud del front Límit Sud. Amb els coeficients de difusió horitzontal obtinguts anteriorment, realitzem simulacions Lagrangianes per a determinar quina fracció de transport roman en el ACC i quina quantitat de transport es desvia al nord per a alimentar el gir subtropical de l'Atlàntic Sud. Els resultats mitjans revelen que 94.8 Sv romanen en el ACC, mentre que un total de 15.1 Sv contribueixen directament a la AMOC. Aquest transport que s'incorpora a la AMOC triga una mediana de 14.3 anys en arribar al corrent del Brasil. Els resultats confirmen que les masses d'aigua que entren al gir subtropical per la vora oriental s'escalfen substancialment i la majoria perden densitat, parcialment transformades en aigües superficials, mentre que les masses d'aigua que romanen a l'ACC es transfereixen en gran mesura a les capes superficials i profundes. A més, s’han comparat les contribucions de la ruta càlida i la ruta freda en el marge oriental del gir subtropical de l'Atlàntic Sud. Amb aquesta fi, realitzem simulacions numèriques per a identificar les múltiples vies directes i indirectes de les aigües intermèdies. La contribució total de les aigües de la ruta freda representa entre un 17.9 i 18.9%, sent substancialment major que el 7.1 i 12.3% de la contribució per part de la ruta càlida. Totes dues rutes estan formades per múltiples vies individuals però la via directa és la via preferent seguida pel 83.6 – 87.2% de les parcel·les d'aigua, sent la ruta freda directa la que sofreix una major transformació de les seves aigües., [spa] La rama de retorno de la circulación meridional del Atlántico (AMOC) es parcialmente sustentada por las aguas frías y frescas que proceden del océano Pacífico a través del pasaje de Drake. Hasta la isoneutra de 28.0 kg m-3, la entrada de agua media a través del paso de Drake hacia el mar de Scotia es de 140.8 ± 7.4 Sv mientras que la salida a través de los pasos del Norte corresponde a 115.9 ± 8.3 Sv. Su componente barotrópica media siempre representa más de la mitad de los transportes totales, con una variación interanual moderada y estacional considerable en los transportes de agua. El tiempo medio estimado de residencia en el mar de Scotia es de unos 6 - 8 meses. Combinando los datos de boyas Argo con otras medidas observacionales y aplicando un modelo inverso climatológico en los límites del mar de Scotia con el fin de definir el flujo de entrada y salida de la ACC hasta la isoneutra de 28.0 kg m-3 se estima que 136.7 ± 1.0 Sv del ACC entran por el paso de Drake y salen 137.9 ± 1.0 Sv por el límite norte. A lo largo de su trayectoria hacia el norte, las aguas del ACC pierden calor pero ganan transporte de agua dulce. Dentro del mar de Scotia, las aguas superficiales- modales y las superficiales-intermedias experimentan producción en todas las variables biogeoquímicas. Finalmente, en cuanto al DIC antropogénico, el mar de Scotia almacena 0.123 Pg C año-1. El método ROD compara los desplazamientos reales de los derivadores con las trayectorias de las partículas simuladas en modelos numéricos; las diferencias observadas-predichas en las posiciones finales responden a movimientos difusivos no capturados por los modelos numéricos. Dicho método es aplicado en el Atlántico Sur occidental obteniendo difusiones máximas de 4630 - 4980 m² s-1 en los primeros 200 m de la columna de agua, presentando una relación inversa con la profundidad. Cerca de la superficie, los coeficientes de difusión son bastante constantes en latitud, sin embargo, a 1000 m los coeficientes disminuyen considerablemente en el sur del frente Límite Sur. Con los coeficientes de difusión horizontal anteriores, se realizan simulaciones Lagrangianas para determinar qué fracción de transporte permanece en la ACC y qué cantidad de transporte se desvía en el norte para alimentar el giro subtropical del Atlántico Sur. Los resultados medianos revelan que 94.8 Sv permanecen en la ACC, mientras que un total de 15.1 Sv contribuyen directamente a la AMOC. Este transporte que se incorpora a la AMOC tarda una mediana de 14.3 años al llegar al corriente del Brasil. Los resultados confirman que las masas de agua que entran al giro subtropical por el borde oriental se calientan sustancialmente y la mayoría pierden densidad, parcialmente transformadas en aguas superficiales, mientras que las masas de agua que permanecen a la ACC se transfieren en gran medida a las capas superficiales y profundas. En cuanto a las contribuciones de la ruta cálida y la ruta fría en el margen oriental del giro subtropical del Atlántico Sur, se realizan simulaciones numéricas para identificar las múltiples vías directas e indirectas de las aguas intermedias. La contribución total de las aguas de la ruta fría representa entre un 17.9 y 18.9%, siendo sustancialmente mayor que el 7.1 y 12.3% de la contribución por parte de la ruta cálida. Ambas rutas están formadas por múltiples vías individuales pero la vía directa es la vía preferente seguida por el 83.6 – 87.2% de las parcelas de agua, siendo la ruta fría directa la que sufre una mayor transformación de sus aguas.

[eng] The biodiversity of a country is part of its natural wealth and the study of it is fundamental for a scientific researcher, such is the case of the Panamanian marine coasts in which there has not been an exhaustive taxonomic description of the Panamanian species of sea slugs. heterobranch recorded by different authors. Here in the first chapter we try to describe the biodiversity of Panamanian sea slugs by providing descriptions of all sea slugs from the coasts of Panama, based on published references and confirmed photographs of all species collected in Panamanian coastal waters; complementing the available information, with specimens collected by us in different Panamanian coastal areas. In a second chapter we cover what happens when climate change and some human activities intervene that contribute to the dispersal of species considered exotic from tropical waters to semi-temperate waters, such as Bursatella leachii. As its introduction into Mediterranean waters has not been well established for this species, we have carried out a molecular analysis study of the populations of this species found on Catalonian coasts to determine the origin of the Mediterranean populations and determine whether the wide Atlantic Ocean is a barrier. natural for this type of species. Furthermore, in a third chapter we compiled the records of Berthella stellata on the Catalan coast and did a study over time of a permanent population of B. stellata in the town of Es Caials (Costa Brava, NE Spain). For this, we collected and photographed live specimens and studied details of their morphology, their radula and jaws, as well as molecular data to compare them with GenBank data from other specimens from different parts of the world, in order to determine to which regions, the Catalan populations of B. stellata. Ending with a fourth chapter where we compare the small red specimens of the Aplysia genus previously considered as Aplysia parvula, with the larger Aplysia punctata. These specimens of A. punctata that inhabit the Catalonian coast show two different color patterns, which are believed to represent two different species. As we do not know why the color change, we set ourselves the goal of knowing what this color change is due to. of the A. punctata. Obtaining in the first chapter a resulting catalog for the coasts of Panama of 233 species, of which 118 are found on the Caribbean coast, 127 on the Pacific coast, eight on both coasts and eighteen Amphi-Atlantic; results that confirm the high biodiversity of heterobranch sea slugs in the Panamanian coasts. In the second chapter we obtained that the haplotypes of B. leachii from the Catalonian coasts are the same as those of the populations of the American Atlantic and Africa, and that the first colonizers of B. leachii possibly entered through the Strait of Gibraltar for those from the Atlantic; concluding that the wide Atlantic Ocean is not a natural barrier. In the third chapter we find that the population of B. stellata from Es Caials shares both morphological and molecular aspects with specimens from the Northeast Atlantic and the Mediterranean in Europe and we conclude with the results of the fourth chapter in which we confirm that the small red specimens of A. punctata feed on red algae, mainly Sphaerococcus coronopifolius and Plocamium cartilagineum; that they give it a morphological appearance very similar to the adults of A. parvula and that the adults of A. punctata feed preferentially on the green algae Ulva lactuca where it hides and escapes from predators. Which led us to conclude that this change in feeding behavior is probably related to defensive camouflage strategies., [spa] La biodiversidad de un país es parte de su riqueza natural y el estudio de ella es fundamental para un investigador científico, tal es el caso de las costas marinas panameñas en la que no ha habido una descripción taxonómica exhaustiva de las especies panameñas de babosas marinas heterobranquias registradas por diferentes autores. Aquí en el primer capítulo tratamos de conocer la biodiversidad de babosas marinas panameñas proporcionando las descripciones de todas las babosas marinas de las costas de Panamá, basadas en referencias publicadas y fotografías confirmadas de todas las especies recolectadas en las aguas costeras panameñas; complementando la información disponible, con ejemplares recolectados por nosotros en diferentes zonas costeras panameñas. En un segundo capítulo abarcamos lo que sucede cuando intervienen el cambio climático y algunas actividades humanas que contribuyen a la dispersión de especies consideradas exóticas de aguas tropicales a aguas semi-templadas, como la Bursatella leachii. Como en esta especie no ha sido bien establecida su introducción en aguas mediterráneas, hemos realizado un estudio de análisis molecular de las poblaciones de esta especie encontradas en costas catalanas para determinar el origen de las poblaciones mediterráneas y determinar si el ancho Océano Atlántico es una barrera natural para este tipo de especies. Además, en un tercer capítulo recopilamos los registros de Berthella stellata en la costa catalana e hicimos un estudio a lo largo del tiempo de una población permanente de B. stellata en la localidad de Es Caials (Costa Brava, NE de España). Para eso recolectamos y fotografiamos ejemplares vivos y se estudiaron detalles de su morfología, su rádula y mandíbulas, así como datos moleculares para compararlos con los datos del GenBank de otros ejemplares de diferentes partes del mundo, con el fin de determinar a qué regiones pertenecen las poblaciones de B. stellata catalanas. Finalizando con un cuarto capítulo en donde comparamos los pequeños ejemplares rojos del género Aplysia considerados anteriormente como Aplysia parvula, con los de mayor tamaño de A. punctata. Estos ejemplares de A. punctata que habitan las costas catalanas muestran dos patrones de coloración diferente, que se cree que representan dos especies distintas, como no sabemos porque el cambio de coloración, nos planteamos el objetivo de saber a qué se debe este cambio de color de las A. punctata. Obteniendo en el primer capítulo un catálogo resultante para las costas de Panamá de 233 especies, de las cuales 118 se encuentran en la costa del Caribe, 127 en la costa del Pacífico, ocho en ambas costas y dieciocho anfiatlánticas; resultados que confirman la alta biodiversidad de babosas de mar heterobranquios en las costas panameñas. En el segundo capítulo obtuvimos que los haplotipos de B. leachii de las costas catalanas son los mismos que los de las poblaciones del Atlántico americano y África, y que los primeros colonizadores de B. leachii posiblemente entraron por el Estrecho de Gibraltar para los del Atlántico; concluyendo que el ancho Océano Atlántico no es una barrera natural. En el tercer capítulo encontramos que la población de B. stellata de Es Caials comparte aspectos tanto morfológicos como moleculares con ejemplares del Atlántico nororiental y del Mediterráneo en Europa y finalizamos con los resultados del cuarto capítulo en cual confirmamos que los pequeños ejemplares rojos de A. punctata se alimentan de algas rojas, principalmente Sphaerococcus coronopifolius y Plocamium cartilagineum; que le dan apariencia morfológica muy similar a los adultos de A. parvula y que los adultos de A. punctata se alimentan preferentemente del alga verde Ulva lactuca en donde se esconde y se escapa de los depredadores. Lo cual nos llevó a concluir que este cambio en el comportamiento alimentario probablemente esté relacionado con estrategias defensivas de camuflaje.

The North Atlantic blue whale was depleted by modern whaling and it is still considered to be highly endangered. Despite its protection in 1954, catches continued in the South European Atlantic Shelf (SEAS) region and immediately adjacent waters until 1979. We compiled catches and investigate abundance trends in the region using original data from whaling (1921–1985) and scientific surveys around the last years of exploitation (1981–1987). The struck and lost rate was estimated at 3.2% for sperm whales and 2.3% for baleen whales. The compiled records include 60 catches, with an additional 1–2 blue whales likely struck and lost. From these, 29 individuals had been correctly reported as blue whales but 31 were mislabelled as fin whales. After correcting for loss rates, the number of blue whales killed in the region was estimated at 61 in 55 years (1.12 individuals/year). The data from the 1950s shows some oversized fin whales but it is unclear whether they are due to an incorrect reporting of species or to incorrect measurements, so it cannot be discarded that the actual number of blue whales caught was slightly higher than estimated. Mean body length of reported blue whales was lower than in higher latitudes of the North Atlantic, probably reflecting geographical stratification with higher proportion of immatures in the SEAS. The ratio between catches or sightings of blue whales and those of fin whales was 5.9% in the southern part of the SEAS previous to exploitation, it declined to 0.02–0.18% in the 1920s, and increased thereafter up to 1.6% in the 1980–1990s. Taking as reference the population size of fin whales in the SEAS, that of blue whales at the end of the 1980s can be guessed to be at ca337-497 individuals. Considering accepted population estimates in other areas as well as the observed rates of increase, current abundance is thought to be over a thousand whales in the SEAs and at in the order of 4000–5000 individuals for the whole eastern North Atlantic basin.

Recovery rates for baleen whales that were decimated by exploitation vary between species and populations. Age determination is critical for the understanding of recovery trends and population structure, but determining age in free-ranging individuals remains challenging. Recent research has suggested that the methylation level of some genes in skin samples may provide age determinations with accuracy. We selected nine CpG sites from three genes (TET2, CDKN2A, and GRIA2) and analyzed them in 40 skin samples from known-age individuals pertaining to two different populations of fin whales from the North Atlantic. We observed significant correlations with age in five CpG sites. We used three of these CpG sites to perform an epigenetic age estimation. Predictions had a standard deviation of 2.94, but regression between observed and predicted ages showed a clear underestimation for older fin whales. For further development, we suggest: (1) screening for new CpG sites associated with age that exhibit higher variability between individuals, and (2) including older animals whenever the sampling allows it. We also observed subtle, but significant differences between the two populations studied in one of the CpG sites (TET2_CpG + 21). We attributed these differences to genetic differences or to the dissimilar environments that affect both populations.

The settlement of demersal animals is influenced both by physical processes ruling the distribution of pelagic juveniles in the open ocean and by their active selection of suitable benthic habitats. Green turtles Chelonia mydas inhabiting the coastal areas of the western South Atlantic Ocean derive primarily from the rookery at Ascension Island and settle over a huge area spanning from northern Brazil to Uruguay. Here, we analysed the stable C and N isotope ratios in 30 µm of carapace layers from juvenile green turtles collected from 2 distinct areas of Brazil (Praia do Forte, 12°38'S, 38°05'W, and Ubatuba, 23°26'S, 45°05'W), with the goal of reconstructing their individual diets and habitat use patterns. Juvenile neritic green turtles from Praia do Forte usually had herbivorous diets, with limited individual variability and few temporal changes in diet or habitat. Conversely, most juvenile green turtles from Ubatuba had omnivorous diets, although they exhibited high levels of individual and temporal variability. These contrasting patterns could be linked to less abundant and predictable food availability in subtropical Ubatuba compared to tropical Praia do Forte. It is unknown why large numbers of juvenile green turtles bypass foraging grounds in north-eastern Brazil to settle in subtropical or warm temperate areas, although it may be related to individual differences in growth rate and their size being too small when reaching Brazil from Ascension Island.

Understanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.

Salt tectonics has a critical role in basin analysis. However, research integrating a salt tectonics perspective is scarce in regional studies along the NW Africa Atlantic passive margin. This study focuses on regional interpretation of unpublished 3D/2D seismic data from the offshore Tarfaya Basin to explore the main controlling factors that influenced its evolution from a salt tectonics approach. Tarfaya Basin constitutes a rifted passive margin developed over thinned continental crust located at the Atlantic margin of southwestern Morocco, east from Fuerteventura and Lanzarote islands. The main factors that conditioned the basin's evolution can be summarized as follows: (1) irregular thickness and distribution of the original salt layer (Upper Triassic); (2) basin tilting caused by thermal subsidence and initial sea-floor spreading phases (Lower Jurassic); (3) development of a mainly carbonatic shelf wedge related to the onset of the incipient Atlantic passive margin (Upper Jurassic); (4) progradation of the Tan Tan delta complex (Lower Cretaceous); (5) compression related to the convergence between African and Eurasian plates (Upper Cretaceous - Recent).

11 pages, 7 figures, 3 tables, This dataset, gathered during the RETRO-BMC cruise, reports multiple-scale measurements at the Confluence of the Brazil and Malvinas Currents. The cruise was carried out between 8 and 28 April 2017 onboard R/V Hespérides, departing from Ushuaia and arriving to Santos. Along its track, the vessel recorded near-surface temperature and salinity, as well as the horizontal flow from 20 m down to about 800 m. A total of 33 hydrographic stations were completed in a region off the Patagonian Shelf, within 41.2°S–35.9°S and out to 53.0°W. At each station, a multiparametric probe and velocity sensors were deployed inside the frame of a rosette used to collect water samples at selected depths; these samples were later used for several water analyses, including inorganic nutrient concentrations. Microstructure measurements were carried out in 11 of these hydrographic stations. In addition, two high-resolution three-dimensional surveys were conducted with an instrumented undulating vehicle between 40.6°S–39.0°S and 55.6°W–53.8°W. Lastly, eight high-frequency vertical profilers were deployed in the region and five position-transmitting drifters were launched. These data allow the description of the Confluence from the regional scale to the microscale, and provide a view of the variability of the frontal region on time scales from days to weeks, This research has been supported by the Spanish government (Ministerio de Economía and Competitividad through project VA-DE-RETRO, CTM2014-56987-P, and Ministerio de Ciencia, Innovación y Universidades through project SAGA, RTI2018‐100844‐BC33). Dorleta Orúe-Echevarría (FPU2013-02884) and Ignasi Vallés-Casanova (BES‐2015‐071314) have also been funded with PhD scholarships by the Spanish government (Ministerio de Ciencia, Innovación y Universidades). Paola Castellanos has been partly supported by the Portuguese government (Fundação para a Ciência e a Tecnologia through project COASTNET, PINFRA/22128/2016), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Salt tectonics play a critical role on passive margins evolution controlling aspects like structural style, subsidence patterns and thermal history, amongst others. The salt-bearing Atlantic passive margin of Morocco hosts one of the oldest stratigraphic records documenting the opening history of the Central Atlantic. However, the available seismic data is scarce and some offshore basins are still poorly studied, particularly in southern Morocco. Through the interpretation of an unpublished 2D/3D seismic dataset from the offshore Tarfaya Basin (SW Morocco), this study aims to highlight the key events that conditioned the evolution of this salt-bearing basin. From proximal to distal regions, the structural style of the basin is characterized by expulsion rollovers and saltcored anticlines delimited by primary welded surfaces, evolving to buried salt sheets surrounded by thick minibasins and finally, diapirs actively deforming the modern seabed. From Late Triassic to Early Jurassic times, salt was deposited with a basinward thickening wedge-shaped geometry on a narrow trough developed over thinned continental crust. During the Jurassic, sedimentation and associated salt withdrawal triggered early salt deformation. Gravity gliding is a common process in salt-bearing passive margins that requires an originally continuous autochthonous salt layer with a minimum slope angle and longitude to thickness ratio of the overburden. However, in the Tarfaya Basin, the narrow geometry of the salt-bearing depocenter hampered this process. Early salt tectonics was probably triggered by slope progradation during the Early Jurassic. During the Early Cretaceous, the progradation of the Tan-Tan Delta promoted a continued basinward expulsion of salt, the development of a local salt-detached gravitational system and the proximal extrusion of salt sheets. Finally, from Late Cretaceous to the Present-day, shortening related to the convergence between Africa and Eurasia resulted in thick-skin inversion and the rejuvenation of precursor salt structures.

The general outline of this thesis was to assess the potential of the Mediterranean water masses to transport deep-sea fauna towards the Atlantic Ocean. By examining the effects that the bathyal water mases moving from the Eastern Mediterranean basin towards the Northeastern Atlantic Ocean may have on the relationships of the deep-water sponge fauna, a case study is provided. Prior to using the sponge fauna as a deep-water biogeographic tool, new collections of deep-sea sponges needed to be conducted in order to increase the faunal resolution at the two most important transitional areas across the bathyal trajectory from the Eastern Mediterranean to the Atlantic, the Strait of Gibraltar and the Strait of Sicily, which remained poorly studied. In this context, the specific objectives of this thesis were as it follows: 1. To complete the previous limited knowledge on the deep-water sponge fauna at key transition areas along the trajectory of the bathyal water mases. 1.1. To provide the missing qualitative and quantitative knowledge of the bathyal sponge fauna at the most Eastern-Atlantic side of the Strait of Gibraltar, focusing on a mud volcano system at the Gulf of Cádiz that spans the entire range of bathyal depths. 1.2. To underpin the qualitative knowledge of the deep-water sponge fauna at the most Western-Mediterranean side of the Strait of Gibraltar, focusing on the deep shelf and upper slope of the Alboran Island. 1.3. To underpin the qualitative knowledge of the deep-water sponge fauna at the Eastern-Mediterranean side of the Strait of Sicily, focusing on the deep shelf and slope of the Maltese Islands. 1.4. To put into practice basic genetic techniques to aid in the identification of species that remain unresolvable through the classical phenetic approach, providing an example case for a more integrative sponge taxonomy. 2. To assess the effects of local environmental variables on the qualitative and quantitative distribution of abundances of the sponges across a complete bathymetric bathyal range, focussing on the mud volcanoes of the Gulf of Cádiz as a case study. 3. To examine the affinities of the deep-water sponge fauna across the trajectory of the bathyal water masses running from the Eastern Mediterranean to the Northeastern Atlantic.

Este artículo contiene 18 páginas, 4 tablas, 5 figuras., Insights into the year-round movements and behaviour of seabirds are essential to better understand their ecology and to evaluate possible threats at sea. The Atlantic petrel Pterodroma incerta is an Endangered gadfly petrel endemic to the South Atlantic Ocean, with virtually the entire population breeding on Gough Island (Tristan da Cunha archipelago). We describe adult phenology, habitat preferences and at-sea activity patterns for each phenological phase of the annual cycle and refine current knowledge about its distribution, by using light-level geolocators on 13 adults over 1−3 consecutive years. We also ascertained moulting pattern through stable isotope analysis (SIA) of nitrogen and carbon in feathers from 8 carcasses. On average, adults started their post-breeding migration on 25 December, taking 10 d to reach their non-breeding areas on the South American shelf slope. The pre-breeding migration started around 11 April and took 5 d. From phenological data, we found evidence of carry-over effects between successive breeding periods. The year-round distribution generally coincided with the potential distribution obtained from habitat modelling, except during the non-breeding and pre-laying exodus periods, when birds only used the western areas of the South Atlantic. Moulting occurred during the nonbreeding period, when birds spent more time on the water, and results from SIA helped us to distinguish feathers grown around Gough Island from those grown in the non-breeding area. Overall, our results bring important new insights into the spatial ecology of this Endangered seabird, which should help improve conservation strategies in the South Atlantic Ocean., The Ministerio de educación y Ciencia and Ministerio de Ciencia e Innovación from the Spanish Government (Projects CGL2006- 01315/BOS, CGL201342585-P, CGL2009-11278/BOS) financially supported this study. Logistical support and financial funding during field work was provided by the South African Department of Environmental Affairs and the National Research Foundation, through the South African National Antarctic Programme, with additional support from the Royal Society for the Protection of Birds. R.R., Z.Z. and J.M.R.G. were supported by Spanish MINECO (Juan de la Cierva postdoctoral programme, JCI-2012-11848), Universitat de Barcelona (UB, APIF/2012) and Spanish MECD (FPU, AP2009-2163), respectively.

[spa] Las especies de peces mesopelágicas que se incluyen en esta investigación corresponden la familia Myctophidae (orden Myctophiformes) con las especies Ceratoscopelus maderensis, Hygophum benoiti y Benthosema glaciale para el mar Mediterráneo y Diaphus vanhoeffeni, Hygophum macrochir, Myctophum affine, M. asperum, M. nitidulum y Gonichthys cocco para el océano Atlántico, y la familia Sternoptychidae (orden Stomiiformes) con las especies Argyropelecus hemigymnus para el Mediterráneo y Argyropelecus sladeni y Sternoptyx diaphana para el océano Atlántico ecuatorial. Finalmente, se ha estudiado también la especie Bathylagoides argyrogaster de la familia Bathylagidae (orden Argentiniformes) del Atlántico. Con objeto de determinar los patrones alimenticios en los primeros estados de desarrollo de las diversas especies, en relación a los cambios morfológicos a lo largo de la ontogenia, su distribución en la columna de agua, y la disponibilidad de presas, se realizaron análisis de contenido intestinal y estomacal. Se calcularon diferentes índices, como la incidencia alimentaria (%FI) y el índice de importancia relativa de cada tipo de presa (%IRI). Para los ejemplares en transformación y juveniles se estimó el contenido de carbono total por estomago (%SCCI) y la tasa diaria de alimentación. Las larvas de las diversas especies de Myctophiformes, Stomiiformes y Argentiniformes se sitúan siempre en la capa fótica, independientemente de cómo sea la distribución de sus adultos y de que estos sean migradores o no. En general la distribución vertical es más amplia por la noche que durante el día, en que están más concentradas en los niveles próximos a superficie. Los ejemplares en estado de transformación presentan un rango de distribución vertical bastante amplio, con pautas de migración menos definidas que los adultos. Las larvas de mictófidos presentaron una compartimentación vertical, siendo las larvas de la subfamilia Lampanyctinae más someras que las de Myctophinae. En cambio, entre las especies que alcanzan la capa neustónica en estado de transformación, juvenil o adulto, dominan las de la subfamilia Myctophinae. Las larvas de mictófidos y las de batilágido se alimentan en las capas más iluminadas y únicamente en las horas de luz. En los estados de transformación los ritmos de alimentación no aparecen definidos, hallándose ejemplares con estómagos vacíos o llenos tanto de día como de noche. Las larvas de los sternoptíchidos, se alimentan tanto de día como de noche. En general, dentro de cada especie, las incidencias alimentarias aumentan hacia etapas de mayor desarrollo, siendo siempre mucho más alta en los ejemplares en estado de transformación. El análisis de los estómagos de los mictófidos en estado de transformación y juveniles del neuston, se alimentan a lo largo de toda la noche, y la máxima ingesta se produce entre las 22:00 y las 24:00 horas. A pesar del incremento en la talla de la boca con el desarrollo, no hay una especialización hacia presas más grandes. Los estados de transformación y juveniles, si bien consumen un mayor número de presas y pueden ingerir presas grandes, siguen consumiendo pequeñas. Las dietas de las diferentes especies a lo largo del desarrollo son muy similares. Los copépodos en diferentes estados de desarrollo son el componente mayoritario de las dietas. Presas grandes como eufausiáceos o hypéridos son exclusivos de los estados de transformación y juveniles, y su presencia en las dietas cambia drásticamente la proporción relativa de presas en términos de carbono. Para los estados de transformación y juveniles de M. affine, M. asperum, M. nitidulum y Gonichthys cocco del neuston se estimaron las tasas diarias de alimentación a partir de una serie de aproximaciones. Los valores obtenidos indican que estos mictófidos son capaces de ingerir ente un 0.1% y 3% de su peso a lo largo del día.

[eng] Despite their small size, phytoplankton represents up to 50% of the global primary production of the Earth and serves as a connector between oceanic and atmospheric processes. Therefore, phytoplankton constitutes a central pillar in the comprehension of the cycles of mass and energy in the oceans. Their different attributes like size, abundance, community composition, functions, pigment complex and taxonomy provide relevant information to understand the processes of global change. In the past decades, the use of HPLC chromatography (High-Performance Liquid Chromatography) has proven as a very effective methodology to study marine phytoplankton. This technique, combined with the use of the statistic program CHEMTAX, allows to identify efficiently the contribution of certain taxonomic classes. This thesis is centered around the use of HPLC-CHEMTAX to identify the phytoplanktonic communities of three regions: the Mediterranean Sea, the Atlantic Ocean and the Antarctic Ocean, each characterized by different trophic conditions (from oligotrophic to eutrophic). With the results obtained, we expect to contribute to the comprehension of the local biochemical responses in a context of global change, as well as to improve future models of ecosystems and algorithms for remote sensing. To validate the data obtained, the results originated from the HPLC-CHEMOTAX were compared to other techniques used for identification and quantification, such as microscopy, flow cytometry and bio-optics. First, we focused on a temporal series (14 years) where we analyzed the seasonal and inter-annual dynamics of the phytoplanktonic community. We have verified that the phytoplanktonic community follows a seasonal pattern, just as had been observed in previous studies: diatoms dominated the blooms of late winter/early spring, while Synechococcus showed maximum abundances during the months of April and August. The cryptophytes and dinoflagellates showed a positive response to sporadic fertilization events, associated mainly to stormy events. In the next study of this thesis, we analyzed the size fractions obtained from sequential filtrations by HPLC-CHEMTAX (total, n+m>3 µm and pico, [spa] El fitoplancton constituye un pilar central necesario para la comprensión de los ciclos de materia y energía de los océanos. Sus atributos como el tamaño, abundancia, comunidades, etc., proporcionan información relevante para entender los procesos de cambio global. En las últimas décadas, el uso de la cromatografía por HPLC se ha revelado como una metodología efectiva para el estudio del fitoplancton marino. Dicha técnica combinada con la utilización del programa estadístico CHEMTAX permite identificar de forma eficiente la contribución de diversas clases taxonómicas. Esta tesis se ha centrado en el uso del HPLC-CHEMTAX para identificar las comunidades fitoplanctónicas en tres regiones: el Mar Mediterráneo, el Océano Atlántico y el Océano Antártico. Con los resultados obtenidos esperamos contribuir a la comprensión de las respuestas biogeoquímicas locales en un contexto de cambios globales, así como mejorar futuros modelos de ecosistemas y algoritmos para sensores remotos. Para validar los datos obtenidos, los resultados provenientes del HPLC-CHEMTAX fueron comparados con otras técnicas de identificación y cuantificación, tales como microscopía, citometría de flujo y bio-óptica. Primeramente, nos centramos en una serie temporal (14 años) donde se analizaron las dinámicas estacionales e interanuales de las comunidades fitoplanctónicas. En el siguiente estudio hemos analizados las fracciones de tamaño obtenidas por filtraciones seriadas con HPLC-CHEMTAX (total, n+m>3 µm y pico

Subsurface water column dynamics in the subpolar North Atlantic were reconstructed in order to improve the understanding of the cause of abrupt ice-rafted detritus (IRD) events during cold periods of the early Pleistocene. We used paired Mg / Ca and δ18O measurements of Neogloboquadrina pachyderma (sinistral – sin.), deep-dwelling planktonic foraminifera, to estimate the subsurface temperatures and seawater δ18O from a sediment core from Gardar Drift, in the subpolar North Atlantic. Carbon isotopes of benthic and planktonic foraminifera from the same site provide information about the ventilation and water column nutrient gradient. Mg / Ca-based temperatures and seawater δ18O suggest increased subsurface temperatures and salinities during ice-rafting, likely due to northward subsurface transport of subtropical waters during periods of weaker Atlantic Meridional Overturning Circulation (AMOC). Planktonic carbon isotopes support this suggestion, showing coincident increased subsurface ventilation during deposition of IRD. Subsurface accumulation of warm waters would have resulted in basal warming and break-up of ice-shelves, leading to massive iceberg discharges in the North Atlantic. The release of heat stored at the subsurface to the atmosphere would have helped to restart the AMOC. This mechanism is in agreement with modelling and proxy studies that observe a subsurface warming in the North Atlantic in response to AMOC slowdown during Marine Isotope Stage (MIS) 3.

Global changes, and particularly the massive release of CO2 to the atmosphere and subsequent global warming, have altered the baselines of carbon and oxygen stable isotopic ratios. Temporal shifts in these baselines can be advantageously monitored through cetacean skin samples because these animals are highly mobile and therefore integrate in their tissues the heterogeneity of local environmental signals. In this study, we examine variation of delta C-13 and delta O-18 values in the skin of fin whales sampled over three decades in two different North Atlantic feeding grounds: west Iceland and northwest Spain. These locations are situated about 2700 km apart and thus represent a wide latitudinal range within the North Atlantic Ocean. The delta C-13 decrease in both areas is attributed to the burning of fossil fuels and increased deforestation worldwide, the so-called Suess effect. The dissimilarity in the magnitude of the shift between the two areas is coincidental with previous information on local shifts and lies within the ranges of variation observed. delta O-18 values experienced a minimal, yet significant change in fin whales from W Iceland (a decline of - 0.44 parts per thousand between 1986 and 2013) but not in those from NW Spain. This is in concordance with a higher rise in temperatures in the former area than in the latter. The study validates the use of cetacean skin to monitor temporal and geographical shifts in stable isotopic values and alerts that, when applying this tool to ecological research, comparisons between sample sets should take into account temporal and latitudinal scales.

Studying the movements of oceanic migrants has been elusive until the advent of several tracking devices, such as the light-level geolocators. Stable isotope analysis (SIA) offers a complementary approach to infer areas used year-round, but its suitability in oceanic environments remains almost unexplored. To evaluate SIA as a tool for inferring movements of oceanic migrants, we sampled an oceanic seabird, the Bulwer's petrel, Bulweria bulwerii, in four breeding colonies spread along its Atlantic distribution. We first studied the species moulting pattern from 29 corpses collected in the colonies. Secondly, based on this moult knowledge, we selected three feathers from tracked birds to infer their breeding and non-breeding grounds using SIA: the 1st primary (P1), the 8th secondary (S8) and the 6th rectrix (R6) feathers. Birds migrated to two main non-breeding areas, the Central or the South Atlantic Ocean. P1 showed similar isotopic values among petrels from different breeding colonies, suggesting this feather is replaced early in the non-breeding period in a common area used by most birds, the Central Atlantic. S8 and R6 feathers correctly assigned 92% and 81%, respectively, of the birds to their non-breeding areas, suggesting they were replaced late in season, when birds were settled in their main non-breeding grounds. Our results showed that the isotopic baseline levels of the Central and South Atlantic are propagated through the food web until reaching top predators, suggesting these ratios can be used to infer the movement of long-distance migrants among oceanic water masses.

Studying the feeding ecology of seabirds is important not only to understand basic aspects of their ecology and threats but also for the conservation of marine ecosystems. In this regard, tropical seabirds have been relatively neglected, and in particular the trophic ecology of tropicbirds is scarcely known. We combined GPS tracking, environmental variables and sampling of regurgitates during incubation and brooding to understand the feeding ecology of red-billed tropicbirds Phaethon aethereus as well as how foraging strategies may change between 2 contrasting marine environments: a coastal island in the Canary Current upwelling (Îles de la Madeleine) and an oceanic island in the middle of the south Atlantic (St Helena). Tropicbirds breeding on the Îles de la Madeleine headed west, foraging on and beyond the shelf slope, probably to associate with subsurface predators which bring pelagic fish close to the surface. Birds from St Helena showed a greater foraging effort and a strong attraction to areas with the greatest species richness of Scombridae, possibly due to a greater difficulty in finding prey in the oligotrophic oceanic waters. Tropicbirds ranged much beyond the extension of the protected areas around their colonies, indicating that current protected areas are insufficient for these populations. We found no evidence to suspect direct mortality of tropicbirds in regional fisheries, but overexploitation of small epipelagic fish and tuna may decrease feeding opportunities and lead to competition with fisheries. The substantial differences in foraging behaviour demonstrated by individuals from both colonies indicates that caution should be taken when extrapolating foraging patterns of tropical seabirds breeding in contrasting oceanographic environments.

The Convention on Biological Diversity aspires to designate 10% of the global oceans as Marine Protected Areas (MPAs), but so far, few MPAs protect pelagic species in the high seas. Transparent scientific approaches are needed to ensure that these encompass areas with high biodiversity value. Here we used the distribution of all globally threatened seabirds breeding in a centrally located archipelago (Tristan da Cunha) to provide guidance on where MPAs could be established in the South Atlantic Ocean. We combined year-round tracking data from six species, and used the systematic conservation-planning tool, 'Zonation', to delineate areas that would protect the largest proportion of each population. The areas used most intensively varied among species and seasons. Combining the sites used by all six species suggested that the most important areas of the South Atlantic are located south of South Africa, around the central South Atlantic between 30 degrees S and 55 degrees S, and near South America. We estimated that the longline fishing effort in these intensively used areas is around 11 million hooks on average each year, highlighting the need for improved monitoring of seabird bycatch rates and the enforcement of compliance with bird bycatch mitigation requirements by fisheries. There was no overlap between the identified areas and any of the existing MPAs in the South Atlantic. The conservation of these highly mobile, pelagic species cannot be achieved by single countries, but requires a multi-national approach at an ocean-basin scale, such as an agreement for the conservation of biodiversity beyond national jurisdiction under the United Nation Convention on the Law of the Sea.

[spa] Los depredadores marinos pueden cambiar su dieta a través del tiempo como consecuencia de cambios antropogénicos y naturales, por lo que un punto de referencia histórico aporta información básica y necesaria para comprender el papel ecológico que desempeñan estos individuos dentro del ecosistema que habitan. En las costas del Atlántico sudoccidental los registros zooarqueologicos e históricos revelan una importante explotación de los lobos marinos sudamericanos por parte de los colonizadores europeos y en menor grado por parte de los aborígenes cazadores recolectores, sin embargo, poco se sabe sobre la influencia de estas explotaciones sobre la dieta de esta especie. Debido a que los lobos marinos sudamericanos se caracterizan por tener un amplio nicho trófico, el determinante principal de la composición de sus dietas es la competencia intraespecifica, por lo que se espera que estos animales muestren un cambio en la posición trófica asociado a la caza indiscriminada por parte de los colonizadores europeos, y un impacto menor sobre sus poblaciones y dietas como resultado de la caza aborigen. En esta tesis doctoral se realizaron análisis de isótopos estables de carbono y nitrógeno en muestras zooarqueológicas y modernas, provenientes del centro-norte y sur de Patagonia Argentina con el objetivo de reconstruir la dieta de los lobos marinos sudamericanos desde el Holoceno tardío al presente. Los resultados revelan un marcado aumento del nivel trófico durante el siglo XX, el cual podría estar relacionado con una disminución del tamaño poblacional del lobo común sudamericano, como consecuencia de la explotación comercial, y una reducción de la competencia intraespecífica. Al contrario, tanto en Patagonia norte-centro como en Patagonia sur, las poblaciones de lobos marinos sudamericanos mostraron una estabilidad en la dieta durante varios milenios de explotación aborigen. Asimismo, no se observaron cambios significativos durante las últimas tres décadas en las razones isotópicas del hueso de machos jóvenes y adultos de lobo marino sudamericano procedentes del sur de Brasil a pesar de un dramático incremento en el desarrollo de la pesquería demersal, lo cual sugiere que la población regional se encuentra muy por debajo de la capacidad de carga. Estos resultados confirman la importancia de los análisis retrospectivos de las razones isotópicos para inferir cambios en la dieta de los depredadores oportunistas, y para identificar la transición ecológica entre ecosistemas prístinos y modificados antropogénicamente., [eng] Marine predators may undergo remarkable dietary changes through time as a result of both anthropogenic and natural changes in the environment, and hence, a historical point of reference provides the necessary basic information to understand the ecological function of individuals in the ecosystem. In the south-west Atlantic coasts, zooarchaeological and historical records revealed a significant exploitation of South American sea lions by European colonizers and to a lesser extent by aboriginal hunter-gatherers, however, little is known about the influence of these exploitations on the diet of sea lions. Because South American sea lions have been reported as broad spectrum, the intraspecific competition plays an important role in the composition of their diets. It is therefore expected a change in the trophic position of these animals associated with the indiscriminate hunting by Western sealing, and less impact on their populations and diets as a result of aboriginal exploitation. Stable isotope ratios of carbon and nitrogen in archaeological and modern samples from northern-central and southern Patagonia, Argentina have been used in this doctoral thesis to reconstruct the dietary changes of the South American sea lion from the late Holocene to the present in the southwestern Atlantic. Results show a marked increase in trophic level during the twentieth century which might be related to the smaller population size resulting from modern sealing and the resulting reduced intraspecific competition. On the contrary, populations of South American sea lions from both in north-central Patagonia and southern Patagonia showed a stability in the diet for several millennia of aboriginal exploitation. Furthermore, no major changes were detected in the diet of male South American sea lions during the past three decades from southern Brazil despite a dramatic increase in the development of demersal fisheries, suggesting that population levels may be below of their optimal carrying capacity Results confirmed the importance of retrospective analysis of the stable isotope ratios to infer changes in the diet of opportunistic predators, and to identify the ecological transition between pristine ecosystems and anthropogenically modified.

Trophic ecology and movements are critical issues for understanding the role of marine predators in food webs and for facing the challenges of their conservation. Seabird forag- ing ecology has been increasingly studied, but small elusive species, such as those forming the 'lit- tle shearwater' complex, remain poorly known. We present the first study on the movements and feeding ecology of the Barolo shearwater Puffinus baroli baroli in a colony from the Azores archi- pelago (NE Atlantic), combining global location-sensing units, stable isotope analyses of feathers (δ 13 C and δ 15 N), stomach flushings and data from maximum depth gauges. During the chick-rear- ing period, parents visited their nests most nights, foraged mainly south of the colony and fed at lower trophic levels than during the non-breeding period. Squid was the most diverse prey (6 fam- ilies and at least 10 different taxa), but species composition varied considerably between years. Two squid families, Onychoteuthidae and Argonautidae, and the fish family Phycidae accounted for 82.3% of ingested prey by number. On average, maximum dive depths per foraging trip reached 14.8 m (range: 7.9 to 23.1 m). After the breeding period, birds dispersed offshore in all directions and up to 2500 km from the breeding colony, and fed at higher trophic levels. Overall, our results indicate that the Barolo shearwater is a non-migratory shearwater feeding at the lowest trophic level among Macaronesian seabirds, showing both diurnal and nocturnal activity and feeding deeper in the water column, principally on small schooling squid and fish. These traits contrast with those of 3 other Azorean Procellariiformes (Cory's shearwater Calonectris diomedea, the Madeiran storm-petrel Oceanodroma castro and Monteiro's storm-petrel O. monteiroi), indi- cating ecological segregation within the Azorean seabird community.

29 pages,8 figures, 9 tables, supporting information https://doi.org/10.1371/journal.pone.0151699, We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal component assemblage), including several pennate taxa, Planktoniella sol, Hemiaulus hauckii and Pseudo-nitzschia spp., in the divergence regions. Our findings indicate that consistent assemblages of co-occurring phytoplankton taxa can be identified and that their distribution is best explained by a combination in different degrees of both environmental and historical influences., This work was supported by Consolider-Ingenio 2010, CSD2008-00077 of the former Spanish Ministerio de Ciencia e Innovación (ES) (Now Ministerio de Economía y Competitividad, www.mineco.gob.es); Consejo Superior de Investigaciones Científicas (CSIC) (ES)

Memoria de tesis doctoral presentada por Jesús Peña Izquierdo para optar al grado de Doctor por la Universitat Politécnica de Catalunya (UPC), realizada bajo la dirección del Dr. Joan Baptista Company Claret, la Dra. Eva Zoe Ramírez Llodra y el Dr. Josep Lluís Pelegrí Llopart del Institut de Ciències del Mar (ICM-CSIC).-- 130 pages, 1 appendix, [EN] Regions isolated from the wind-driven circulation are found in the eastern margins of the world’s tropical oceans. The weak and stagnant circulation of these so-called ‘shadow zones’, in combination with the intense respiration of organic matter provided by the overlying highly productive waters, promotes the existence of large oceanic volumes with very low dissolved oxygen. These volumes are known as oxygen minimum zones (OMZs). The last decades of observations have revealed that OMZs are in general expanding, and thus potentially threatening the surrounding rich marine ecosystems. However, it is not clear whether this change is based on natural variability or it has an anthropogenic origin. Furthermore, under a global warming scenario, the future evolution of the OMZs is uncertain due to the complex interaction between the physical and biochemical processes that interplay in the OMZs dynamics. [...], This thesis investigation was conducted between 2009 and 2014 under the guidance of Dr. José Luís Pelegrí Llopart, who is an investigator from the Institut de Ciències del Mar - Consejo Superior de Investigaciones Científicas, supported through an FPI predoctoral grant (BES-2009-021691) in the frame of the research project entitled “Ocean Climate Memory: mechanisms and paths of surface water formation in the Equatorial Atlantic” (MOC2-Ecuatorial, ref. CTM2008-06438-C02-01/MAR)

From the early 17th century to the 1970s southern right whales, Eubalaena australis, were subject to intense exploitation along the Atlantic coast of South America. Catches along this coast recorded by whalers originally formed a continuum from Brazil to Tierra del Fuego. Nevertheless, the recovery of the population has apparently occurred fragmentarily, and with two main areas of concentration, one off southern Brazil (Santa Catarina) and another off central Argentina (Peninsula Valdés). This pattern suggests some level of heterogeneity amongst the population, which is apparently contradicted by records that traced individuals moving throughout the whole geographical extension covered by the species in the Southwest Atlantic. To test the hypothesis of the potential occurrence of discrete subpopulations exploiting specific habitats, we investigated N, C and O isotopic values in 125 bone samples obtained from whaling factories operating in the early 1970s in southern Brazil (n = 72) and from contemporary and more recent strandings occurring in central Argentina (n = 53). Results indicated significant differences between the two sampling areas, being δ13C and δ18O values significantly higher in samples from southern Brazil than in those from central Argentina. This variation was consistent with isotopic baselines from the two areas, indicating the occurrence of some level of structure in the Southwest Atlantic right whale population and equally that whales more likely feed in areas commonly thought to exclusively serve as nursing grounds. Results aim at reconsidering of the units currently used in the management of the southern right whale in the Southwest Atlantic Ocean. In the context of the current die-off affecting the species in Peninsula Valdés, these results also highlight the necessity to better understand movements of individuals and precisely identify their feeding areas. Fil: Morgana, Vighi. Universidad de Barcelona; España Fil: Borrell, Asunción. Universidad de Barcelona; España Fil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina Fil: Oliveira, Larissa R.. Universidade Vale do Rio dos Sinos; Brasil. Universidade Federal do Rio Grande do Sul; Brasil Fil: Simões Lopes, Paulo C.. Universidade Federal Santa Catarina; Brasil Fil: Flores, Paulo A. C.. Centro Nacional de Pesquisa e Conservaçào de Mamíferos Aquáticos; Brasil Fil: Garcia, Nestor Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina Fil: Aguilar, Alejandro. Universidad de Barcelona; España

18 pages, 4 figures, 1 table, Polyunsaturated aldehydes (PUAs) are organic compounds mainly produced by diatoms, after cell wounding. These compounds are increasingly reported as teratogenic for species of grazers and deleterious for phytoplanktonic species, but there is still scarce information regarding concentration ranges and the composition of PUAs in the open ocean. In this study, we analyzed the spatial distribution and the type of aldehydes produced by the large-sized (>10 μm) phytoplankton in the Atlantic Ocean surface. Analyses were conducted on PUAs released after mechanical disruption of the phytoplankton cells, referred to here as potential PUAs (pPUAs). Results show the ubiquitous presence of pPUA in the open ocean, including upwelling areas, as well as oligotrophic gyres. Total pPUA concentrations ranged from zero to 4.18 pmol from cells in1 L. Identified PUAs were heptadienal, octadienal and decadienal, with heptadienal being the most common (79% of total stations). PUA amount and composition across the Atlantic Ocean was mainly related to the nitrogen:phosphorus ratio, suggesting nutrient-driven mechanisms of PUA production. Extending the range of trophic conditions considered by adding data reported for productive coastal waters, we found a pattern of PUA variation in relation to trophic status. © 2014 by the authors; licensee MDPI, Cruises were carried out within the framework of the Spanish Circumnavigation Expedition Malaspina 2010 (Ref. CSD2008-00077). GC-MS analyses were funded by project INDIAL (Ref. CTM 2008/01198). These projects were all funded by the Spanish Ministry of Economy and Competitiveness. [...] This is the contribution N° 48 of the CEI·MAR Journal Series

15 pages, 5 figures, 5 tables, Aim. Apical pelagic species forage in predictable habitats, and their movements should signal biologically and ecologically significant areas of the marine ecosystem. Several countries are now engaged in identifying these areas based on animal tracking, but this is often limited to a few individuals from one breeding population, which may result in biased portrayals of the key marine habitats. To help identify such foraging areas, we compiled tracking data of a marine top predator from the main breeding colonies in the Central Macaronesia. Location. North-east Atlantic Ocean. Methods. Over seven years, we tracked the foraging movements of Cory's shearwaters (Calonectris borealis) from several populations during the chick-rearing period using global positioning system and platform terminal transmitter devices. Results. We obtained foraging trips from 174 shearwaters breeding on six important colonies representative of the range occupied in the Macaronesian Archipelagos of Madeira, Salvages and Canaries. Our results show that birds orient and move rapidly towards the closest neritic waters over the African continental shelf. Birds from different colonies show substantial spatial segregation in their foraging grounds but consistently overlap in some specific foraging areas along the Canary Current characterized by high productivity. By weighting the use of foraging grounds according to the size of each study population, we inferred the overall exploitation of such areas. Main conclusions. Our meta-population approach provides a more comprehensive picture of space use from both perspectives: the studied species and the Canary Current system. Foraging grounds consistently used by several populations may not be adequately identified by tracking a single population, and therefore, multiple population tracking studies are needed to properly delineate key conservation areas and inform conservation planning in the marine ecosystem. Finally, we highlight the long-term stability and sustainability of identified foraging areas and propose that countries with geographical jurisdictions over the Canary Current area should work towards multilateral agreements to set management plans for this key marine ecosystem, We are thankful to A. Almeida, H. Alonso, M. N. Carrasco, T. Catry, M.P. Dias, L. Gangoso, M. Lecoq, J. M. Mart ínez, R. Mart ínez, A. Padr on, J. Prieto, A. Rodr íguez, T. Militão, X. Moreno, M. L opez, J. Ferrer, L. Est evez and C. Canella for their field and logistic support. Parque Natural da Madeira and several Cabildos Insulares provided permissions and logistical support. We are also indebted with E. Batllori for helping with spatial modelling and M. Brooke for reviewing an earlier manuscript. RR, JN, VHP and JMR-G were supported by respective programmes of Beatriu de Pin os (2010-BP_A-00173), Juan de la Cierva (JCI-2009-05426), Fundac ~ao para a Ciência e Tecnologia (FCT; SFRH/BPD/63825/2009) and Formaci on de Profesorado Universitario (FPU; AP2009-2163). This study was financed by European Union (EU), the Spanish Ministerio de Educaci on y Ciencia (MEyC) and the Portuguese FCT through different projects: LIFE04NAT/ES/000049(EU), LIFE04NAT/PT/000213(EU), LIFE07NAT/E/000732(EU), LIFE09NAT/PT/000041(EU), REN2002-01164(MEyC), CGL2006-01315/BOS(MEyC), CGL2009-11278/BOS(MEyC), PTDC/MAR/71927/2006(FCT) and PEst-OE/MAR/UI0331/2011(FCT)

Early and Mid-Pleistocene climate, ocean hydrography and ice sheet dynamics have been reconstructed using a high-resolution data set (planktonic and benthic delta O-18 time series, faunal-based sea surface temperature (SST) reconstructions and ice-rafted debris (IRD)) record from a high-deposition-rate sedimentary succession recovered at the Gardar Drift formation in the subpolar North Atlantic (Integrated Ocean Drilling Program Leg 306, Site U1314). Our sedimentary record spans from late in Marine Isotope Stage (MIS) 31 to MIS 19 (1069-779 ka). Different trends of the benthic and planktonic oxygen isotopes, SST and IRD records before and after MIS 25 (similar to 940 ka) evidence the large increase in Northern Hemisphere ice-volume, linked to the cyclicity change from the 41-kyr to the 100-kyr that occurred during the Mid-Pleistocene Transition (MPT). Beside longer glacial-interglacial (G-IG) variability, millennial-scale fluctuations were a pervasive feature across our study. Negative excursions in the benthic delta O-18 time series observed at the times of IRD events may be related to glacio-eustatic changes due to ice sheets retreats and/or to changes in deep hydrography. Time series analysis on surface water proxies (IRD, SST and planktonic delta O-18) of the interval between MIS 31 to MIS 26 shows that the timing of these millennial-scale climate changes are related to half-precessional (10 kyr) components of the insolation forcing, which are interpreted as cross-equatorial heat transport toward high latitudes during both equinox insolation maxima at the equator.

13 páginas, 2 figuras, 4 tablas., Feeding ecology and geographic location are 2 major factors influencing animal stable isotope signatures, but their relative contributions are poorly understood, which limits the usefulness of stable isotope analysis in the study of animal ecology. To improve our knowledge of the main sources of isotopic variability at sea, we determined δ15N and δ13C signatures in the first primary feather of adult birds from 11 Procellariiform species (n = 609) across 16 northeast Atlantic localities, from Cape Verde (20°N) to Iceland (60°N). Post-breeding areas (where the studied feather is thought to be grown) were determined using light-level geolocation for 6 of the 11 species. Isotopic variability was geographically unstructured within the mid-northeast Atlantic (Macaronesian archipelagos), but trophically structured according to species and regardless of the breeding location, presumably as a result of trophic segregation among species. Indeed, the interspecific isotopic overlap resulting from combining δ15N and δ13C signatures of seabirds was low, which suggests that most species exploited exclusive trophic resources consistently across their geographic range. Species breeding in north temperate regions (Iceland, Scotland and Northern Ireland) showed enriched N compared to the same or similar species breeding in tropical and subtropical regions, suggesting some differences in baseline levels between these regions. The present study illustrates a noticeable trophic segregation of northeast Atlantic Procellariiformes. Our results show that the isotopic approach has limited applicability for the study of animal movements in the northeast Atlantic at a regional scale, but is potentially useful for the study of long-distance migrations between large marine systems., J.L.R. and E.G.-D. were supported by a postgraduate grant from the Generalitat de Catalunya, V.N. by a postgraduate grant of the Portuguese Fundaçáo para a Ciênciaea Tecno - logia/ Foundation for Science and Technology and J.G.-S. by the Ramon y Cajal programme. This work benefited from support by the Ministerio de Ciencia e Innovación (CGL2009-11278/BOS) and Fondos Feder.

The Mid-Pleistocene transition (MPT) was the time when quasi-periodic (not, vert, similar 100 kyr), high-amplitude glacial variability developed in the absence of any significant change in the character of orbital forcing, leading to the establishment of the characteristic pattern of late Pleistocene climate variability. It has long been known that the interval around 900 ka stands out as a critical point of the MPT, when major glaciations started occurring most notably in the northern hemisphere. Here we examine the record of climatic conditions during this significant interval, using high-resolution stable isotope records from benthic and planktonic foraminifera from a sediment core in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313). We have considered the time interval from late in Marine Isotope Stage (MIS) 23 to MIS 20 (910 to 790 ka). Our data indicate that interglacial MIS 21 was a climatically unstable period and was broken into four interstadial periods, which have been identified and correlated across the North Atlantic region. These extra peaks tend to contradict previous studies that interpreted the MIS 21 variability as consisting essentially of a linear response to cyclical changes in orbital parameters. Cooling events in the surface record during MIS 21 were associated with low benthic carbon isotope excursions, suggesting a coupling between surface temperature changes and the strength of the Atlantic meridional overturning circulation. Time series analysis performed on the whole interval indicates that benthic and planktonic oxygen isotopes have significant concentrations of spectral power centered on periods of 10.7 kyr and 6 kyr, which is in agreement with the second and forth harmonic of precession. The excellent correspondence between the foraminifera δ18O records and insolation variations at the Equator in March and September suggests that a mechanism related to low-latitude precession variations, advected to the high latitudes by tropical convective processes, might have generated such a response. This scenario accounts for the presence of oscillations at frequencies equal to precession harmonics at Site U1313, as well as the occurrence of higher amplitude oscillations between the MIS22/21 transition and most of MIS 21, times of enhanced insolation variability.

10 páginas, 1 figura, 1 tabla., [EN] A list of opisthobranch molluscs species from the western Mediterranean and nearby Atlantic is presented. These species have natural products that are of interest because of their chemical structure, origin and/or function in benthic ecosystems. This review contains data on the origin and activity of these molecules, collection sites of the animals, and their bibliographic references. A discussion of these subjects is also included., [ES] Se presenta un listado de especies de moluscos opistobranquios del Mediterráneo occidental y Atlántico próximo, que poseen substancias naturales de interés por su estructura química, su origen y/o su función en ecosistemas bentónicos. Se incluyen datos sobre el origen y la actividad de estas substancias, los lugares de procedencia de los animales estudiados, las referencias bilbiográficas relacionadas, así como una discusión sobre los mismos., This work has been supported by F.I. fellowship from the Generalitat de Catalunya and is part of the author's doctoral thesis. Financial support of the C.I.C.Y.T. from the Spanish Government is also acknowledged (MAR 91-0528).

La presente tesis recoge los resultados de la investigación desarrollada por el autor durante los años 1978-1984 en los ejemplares de rorcual común capturados en las factorías balleneras españolas, así como estudios realizados durante este tiempo de las fuentes estadísticas disponibles de períodos anteriores. Dado que la población ibérica de rorcual común ha sido objeto de explotación desde el año 1921, gran parte de las investigaciones se dirigieron a los aspectos de biología poblacional necesarios para la gestión y mantenimiento de dicha población.Morfología: La población estudiada se caracteriza por una relativa similitud en sus proporciones corporales respecto a otras del hemisferio norte, pero se diferencia de las del hemisferio sur por poseer unas aletas pectorales menores y una aleta dorsal más centrada. Durante el crecimiento embrionario, la parte central del cuerpo crece más rápidamente, disminuyendo progresivamente la importancia relativa de la porción cefálica y caudal.Alimentación: La alimentación de Balaenoptera physalus en aguas ibéricas consiste principalmente en eufausiáceos, en especial Meganyctiphanes norvegica, aunque puede consumir ocasionalmente otras especies de crustáceos o peces de pequeño tamaño.Factores de mortalidad natural: En las aguas ibéricas, el rorcual común tiene pocos depredadores. La incidencia de malformaciones, enfermedades o infestaciones parasitarias es relativamente baja y no ha sido posible detectar causas de mortalidad natural particularmente significativas. La contaminación por compuestos organoclorados es muy baja en comparación con otras especies de cetáceos y no se cree que tenga efecto nocivo alguno.Distribución y migración: Se considera que la población ocupa un área de distribución comprendida entre la costa de Marruecos y el norte de las Islas Británicas. Dentro de esta área, las ballenas se desplazan latitudinalmente, alcanzando las aguas del noroeste de la Península Ibérica durante los meses centrales del verano.Determinación de la edad: La longitud de la médula del cono de cera es un buen indicador de la edad durante los primeros 20 años de vida, pero pierde fiabilidad a partir de esta edad. Las bandas de crecimiento del cono son útiles para todas las edades, aunque en las hembras su interpretación se hace más difícil con la edad.Crecimiento: Los machos tienen un tamaño máximo de 18,95 m y las hembras de 20,41 m. La tasa de crecimiento es mayor en los primeros, por lo que alcanzan su tamaño definitivo a una edad más temprana que las segundas. La madurez física se alcanza en ambos sexos entre los 20 y los 30 años de edad.Mortalidad: La evolución de las tasas de mortalidad indica que la población ha sufrido una mayor presión de captura en épocas recientes. Las estimas combinadas de mortalidad total son del 11 % en machos y del 12 % en hembras, debiéndose la diferencia a una aparente mayor mortalidad natural de las hembras mayores de 25 años. La edad máxima observada fue de 84 años, en un macho.Actividad folicular en el ovario: La actividad es mínima en los ejemplares inmaduros pero aumenta a medida que se aproximan a su primer estro. Durante la ovulación el desarrollo folicular es alto, alcanza un máximo durante la gestación, y se deprime durante la lactancia, activándose de nuevo durante la temporada de reposo sexual.Maduración sexual: En promedio, la maduración sexual tiene lugar a los 7,5 años de edad y 18,5 m de talla en las hembras, y a los 6,6 años y a los 17,6 m en los machos. En la fase de transición de los conos de cera se observa un descenso de la edad media de maduración sexual desde los 9-10 años de edad, durante la década de 1920, hasta los valores actuales.Ovulación: La población estudiada tiene una tasa de ovulación de un estro cada algo más de dos años, no pareciendo que la tasa disminuya con la edad ni aún en los ejemplares más viejos. El estro se produce en invierno, ovulando tan sólo un 7% aproximadamente de las hembras no gestantes durante el verano. Un 2 % experimenta un estro durante la lactancia.Gestación y lactancia: La curva de crecimiento fetal y el desarrollo de los folículos ováricos indican que el máximo de concepciones se produce en la primera quincena de enero. El parto tiene lugar once meses más tarde, a finales de noviembre, cuando el feto alcanza los 6 m de talla y 1,5 toneladas de peso. La tasa de fecundidad es de 0,38, lo que indica que las hembras maduras tienen unas dos gestaciones cada cinco años. El período de lactancia se estima en unos 8-9 meses. El destete se produce al alcanzar la cría la talla de 13 m. Después del destete, las hembras suelen permanecer sexualmente inactivas hasta el estro invernal, unos 2-3 meses más tarde.Desarrollo testicular: El desarrollo de los túbulos seminíferos y el peso de los testículos están más ligados a la edad de la ballena que a su talla. Al alcanzar la madurez sexual el peso de cada testículo es de unos 3 Kg. El testículo derecho es de dimensiones significativamente mayores que el izquierdo, aunque el desarrollo de los túbulos seminíferos es semejante en ambos testículos. El testículo no muestra variaciones estacionales durante el período comprendido entre los meses de junio a octubre, por lo que no es posible establecer a partir de éste la época en que tiene lugar el apareamiento.Composición de las capturas: Las estadísticas de los primeros años de explotación muestran una composición de capturas similar entre las distintas localidades (estrecho de Gibraltar, costa de Portugal y Galicia).Tamaño de población en la década de 1920: A partir de la relación entre la captura por unidad de esfuerzo y las capturas totales es posible estimar la población explotable virginal en unos 6.000-10.000 ejemplares. El valor más probable es de 6.300. Al final de 1928, cuando se interrumpieron las operaciones, la población había sido reducida a tan sólo 1.400 ballenas.Variaciones en el tamaño de población: Desde 1928 hasta 1975 parece que la población se recuperó a un ritmo bastante constante, alcanzando un tamaño máximo al final de este período, desde donde se redujo a unas 3.400 en 1984. Las estimas de marcaje sugieren una población mínima de 1.500-2.000 ejemplares en 1984.

En este trabajo se presenta un estudio de los parámetros dinámicos de terremotos ocurridos bajo las dorsales del Atlántico y Oriental del Pacífico, así como de la variación regional del coeficiente de atenuación de las ondas Rayleigh para la región oriental del Pacífico. Se ha obtenido un coeficiente de atenuación anormalmente alto bajo la dorsal del Pacífico e importantes diferencias en las condiciones de similaridad para las dos dorsales. Comparando los parámetros dinámicos obtenidos para las dorsales (zonas de tensión) con parámetros obtenidos para zonas de subducción (zonas de compresión), resultan ser similares excepto para la caída de esfuerzos. Los resultados obtenidos se interpretan en función de la actividad tectónica de las dorsales.

In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen-isotope ratios (delta O-18) in the inorganic component (hydroxyapatite), and nitrogen and carbon isotope ratios (delta N-15: delta C-13) in the organic component (primarily collagenous). We found significant differences between Denmark and NW Spain in delta N-15 and delta O-18 values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in delta N-15, delta C-13 and delta O-18 values in the period up to age 20, and in the ontogenetic variation of delta N-15 and delta O-18 values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted.

Aim Anthropogenic activities alter and constrain the structure of marine ecosystems with implications for wide-ranging marine vertebrates. In spite of the environmental importance of vast oceanic ecosystems, most conservation efforts mainly focus on neritic areas. To identify relevant oceanic areas for conservation, we assessed the year-round spatial distribution and spatio-temporal overlap of eight truly oceanic seabird species of gadfly petrels (Pterodroma spp.) inhabiting the Atlantic Ocean. Location Atlantic Ocean. Methods Using tracking data (mostly from geolocators), we examined year-round distributions, the timing of life-cycle events, and marine habitat overlap of eight gadfly petrel species that breed in the Atlantic Ocean. Results We compiled 125 year-round tracks. Movement strategies ranged from non-migratory to long-distance migrant species and from species sharing a common non-breeding area to species dispersing among multiple non-breeding sites. Gadfly petrels occurred throughout the Atlantic Ocean but tended to concentrate in subtropical regions. During the boreal summer, up to three species overlapped spatio-temporally over a large area around the Azores archipelago. During the austral summer, up to four species coincided in a core area in subtropical waters around Cape Verde, and three species shared habitat over two distinct areas off Brazil. The petrels used many national Exclusive Economic Zones, although they also exploited offshore international waters. Main conclusions Tracking movements of highly mobile vertebrates such as gadfly petrels can provide a powerful tool to evaluate and assess the potential need for and location of protected oceanic areas. As more multispecies, year-round data sets are collected from wide-ranging vertebrates, researchers and managers will have greater insight into the location of biodiversity hotspots. These can subsequently inform and guide marine spatial planning efforts that account for both conservation and sustainable use of resources such as commercial fisheries.

The strong influence of the winter North Atlantic Oscillation (NAO) on the total ozone column (TOC) in the Northern Hemisphere has been reported in a number of previous studies. In this study we show that this influence is not restricted to the winter season but is also significant in summer. Especially interesting effects of the summer NAO (SNAO) on the TOC are observed over the eastern Mediterranean region, where a strongly positive SNAO index is related to the creation of a geopotential height-negative anomaly over Greece with maximum amplitude at 200 hPa. Another anomaly was observed west of the Iberian Peninsula with similar effects on the TOC. Analyzing 26 years of Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) data from the equator to midlatitudes (60°) in the Northern Hemisphere, we demonstrate that the SNAO accounts for up to 30% of the TOC variability with a strong latitudinal and longitudinal dependence. Additionally, we obtain significant correlations between the NAO index and the thermal tropopause pressure and also with the geopotential heights at 200 and 500 hPa. Finally, some indirect connections between NAO and the TOC through teleconnections are also discussed.