A global ‘greening’ of coastal dunes: An integrated consequence of climate change?

In the context of global climate change and sea-level rise, coastal dunes are often important elements in the coastal response to storm wave and storm surge impacts on coastal lowlands. Vegetation cover, in turn, has profound impacts on coastal dune morphology and storm-buffering function; it binds existing sediment, promotes fresh sediment accumulation and thereby increases dune volume and dune crest elevation where a sediment-plant interaction plays out with vegetation growth attempting to out-pace the vertical sediment accumulation. A global analysis shows that vegetation cover has increased substantially on multiple, geographically dispersed, coastal dune fields on all continents in the period 1984-2017. The observed 'greening' points to enhanced dune stability and storm buffering effects at a time when, paradoxically, coasts are being subjected to increased flood and erosion risk from rising sea levels and changing patterns of storminess. Causal attribution of biological trends to climate change is complicated, but we contend that the global scale 'greening' of coastal dunes is driven by a combination of changes to climate and atmospheric composition and reflects the cumulative effects of changes in temperature, precipitation, nutrient concentration and reduced windiness (global stilling). Global-scale increases in temperature, nutrients and precipitation (all of which are vegetation growth stimulants) and widespread reduction in windiness ("stilling") (which reduces sediment activity, promoting the spread of vegetation) coincide in time with the observed changes in vegetation cover. The observed changes in coastal dunefields enhance contemporary and near-future coastal resilience to climate change and may represent a previously unrecognised morphological feedback mediated by climate change.Agência financiadora NERC Natural Environment Research Council NE/F019483/1 NERC Geophysical Equipment Facility Grant 1082 "FCT Investigator" program IF/01047/2014 CIMA of the University of Algarve UID/MAR/00350/2013 Xunta de Galicia PlanI2C-ED481B 2018/021info:eu-repo/semantics/publishedVersio

BENFEP, a quantitative database of BENthic Foraminifera from surface sediments of the Eastern Pacific

Foraminifera are important components of the ocean benthos and play a major role in ocean biogeochemistry and ecosystems functioning. Generating ecological baselines for ocean monitoring or biogeographical distributions requires a reference dataset of recent census data. Besides, the information from their modern biogeography can be used to interpret past environmental changes on the sea-floor. In this study, we provide the first comprehensive quantitative BENthic Foraminifera database from surface sediments of the Eastern Pacific (BENFEP). Through the collation of archival census data and its homogenization according to the most recent taxonomic standards, we are able to provide a database with 3093 sediment samples, corresponding to 2572 georeferenced stations of wide geographical coverage (60&ordm; N and 54&ordm; S) and water depths (0&ndash;7642 m). The quantitative data includes living, dead, and living and dead assemblages obtained from 47 published and unpublished documents. As well as describing the data collection and subsequent harmonization steps, we provide summarized information of metadata variables, examples of species distribution, potential applications of the database and recommendations for data archiving and publication of benthic foraminiferal data. The database is enriched with meaningful metadata for accessible data management and exploration with R and geospatial software. BENFEP will be upgraded with new records. We complement BENFEP with an additional database integrating metadata and stations geolocation of benthic foraminiferal studies dearth of quantitative data (BENFEPqual).</p

Impact of atmospheric circulation patterns on coastal dune dynamics, NW Spain

Dunes in temperate latitudes have experienced a significant stabilization in recent times, essentially as a consequence of the expansion of dense vegetation cover. Yet, the causes for this gradual stabilization as well as the causes promoting antecedent aeolian mobilization remain poorly understood. The Traba coastal dune field, located in NW Spain, was examined to explore the causes inducing aeolian activity and subsequent stabilization since 1940. Morphological changes were identified through the combination of aerial photographs and geophysical techniques. Local wind field regimes were simulated using a regional climate model to obtain the variability of the most relevant modes of atmospheric circulation in the North Atlantic and European regions; North Atlantic Oscillation (NAO), Eastern Atlantic (EA) and Scandinavian (SCAND). This allows us to identify the impact of these circulation modes over dune dynamics. Results document an episode of aeolian activity during the 1950s followed by a gradual stabilization and fixation of the dune coincident with a decrease on storm and wind intensity. Yet, aeolian sand movement remained active in small areas (blowouts), occurring mainly during the summer. NE winds associated with a negative phase of the EA explain the movement of sand within the dune field under favorable conditions of sand supply. On the other hand, sand supply to the dune field from the beach was promoted by NW winds coincident with the summer negative phase of NAO. During winter, the negative NAO favored frequent SW winds associated with the passage of intense storms, which in turn explain sand remobilization from the beach making sediment available for the NW winds to blow inland. With this work, it is proven that to understand past and future aeolian activity requires critical consideration of the variability and impact of the two principal modes of atmospheric circulation in the North Atlantic (NAO and EA). The SCAND mode explaining a lower percentage of the local wind field variability was also included to achieve higher significance levels of explained variance

8000 years of environmental evolution of barrier–lagoon systems emplaced in coastal embayments (NW Iberia)

The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and vulnerable, small and shallow barrier– lagoon systems structurally controlled. The case study was selected to analyse barrier–lagoon evolution based on detailed sedimentary architecture, chronology, geochemical and biological proxies. The main objective is to test the hypothesis of structural control and the significance at regional scale of any highenergy event recorded. This work is also aimed at identifying general patterns and conceptualizing the formation and evolution of this type of coastal systems. The results allowed us to establish a conceptual model of Holocene evolution that applies to rock-bounded barrier–lagoon systems. The initial stage (early Holocene) is characterized by freshwater peat sedimentation and ended by marine flooding. The timing of the marine flooding depends on the relation between the elevation of the basin and the relative mean sea-level position; the lower the topography, the earlier the marine inundation. Thus, the age of basin inundation ranged from 8 to 4 ka BP supporting significant structural differences. Once marine inundation occurred, all systems followed similar evolutionary patterns characterized by a phase of landward barrier migration and aeolian sedimentation towards the back-barrier (i.e. retrogradation) that extended circa 3.5 ka BP. The later phases of evolution are characterized by a general trend to the stabilization of the barriers and the infilling of the lagoons. This stabilization may be temporally interrupted by episodes of enhanced storminess or sediment scarcity. In this regard, washover deposits identified within the sedimentary architecture of the case study explored here suggest pervasive high-energy events coeval with some of the cooling events identified in the North Atlantic during the mid- to late Holocene

8000 years of environmental evolution of barrier–lagoon systems emplaced in coastal embayments (NW Iberia)

The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and vulnerable, small and shallow barrier– lagoon systems structurally controlled. The case study was selected to analyse barrier–lagoon evolution based on detailed sedimentary architecture, chronology, geochemical and biological proxies. The main objective is to test the hypothesis of structural control and the significance at regional scale of any highenergy event recorded. This work is also aimed at identifying general patterns and conceptualizing the formation and evolution of this type of coastal systems. The results allowed us to establish a conceptual model of Holocene evolution that applies to rock-bounded barrier–lagoon systems. The initial stage (early Holocene) is characterized by freshwater peat sedimentation and ended by marine flooding. The timing of the marine flooding depends on the relation between the elevation of the basin and the relative mean sea-level position; the lower the topography, the earlier the marine inundation. Thus, the age of basin inundation ranged from 8 to 4 ka BP supporting significant structural differences. Once marine inundation occurred, all systems followed similar evolutionary patterns characterized by a phase of landward barrier migration and aeolian sedimentation towards the back-barrier (i.e. retrogradation) that extended circa 3.5 ka BP. The later phases of evolution are characterized by a general trend to the stabilization of the barriers and the infilling of the lagoons. This stabilization may be temporally interrupted by episodes of enhanced storminess or sediment scarcity. In this regard, washover deposits identified within the sedimentary architecture of the case study explored here suggest pervasive high-energy events coeval with some of the cooling events identified in the North Atlantic during the mid- to late Holocene

Evolution of the southern dune sector of the Corrubedo complex

El estudio de las barreras arenosas costeras es fundamental porque éstas sirven de protección a otros ambientes con elevada importancia ecológica y productividad (marismas, lagunas costeras y estuarios). Sin embargo, estas barreras son ambientes altamente susceptibles a la erosión y se pueden ver afectadas por diferentes factores como cambios en el nivel del mar, oleaje, mareas, corrientes, disponibilidad de sedimento, pendiente y geomorfología del fondo marino, configuración de la línea de costa y la topografía heredada. En este trabajo se presenta una hipótesis de la evolución de la barrera costera de Corrubedo. Para el estudio de esta barrera costera se han utilizado diferentes metodologías, como el análisis de fotografías aéreas, georadar y sondeos. Por otra parte, se han datado distintos niveles mediante OSL y radiocarbono para reconstruir la historia sedimentaria. Se han reconocido un total de cuatro fases principales en el sector sur del complejo de Corrubedo. Estas fases se caracterizan por la alternancia de depósitos de grano fino y de grano grueso. Las dataciones de radiocarbono indican que la sedimentación comenzó con anterioridad a los 4500 años cal BP. En los registros de georadar se observan evidencias de la presencia del basamento a poca profundidad; lo que sugiere la influencia de la topografía heredada sobre la arquitectura resultante debido a: 1) reducción del espacio de acomodación y en consecuencia una reducción de la capacidad de almacenamiento y 2) la posición del basamento proporciona a la vez un substrato fijo que ancle la barrera y mantenga la línea de costa en una posición relativamente estable en el tiempoCoastal sand barriers are of high environmental significance because they provide protection for highly productive landward environments. However, they are also highly vulnerable environments as they can be affected by different factors such as sea-level changes, storm waves, tides, currents, sediment supply, seafloor slope and morphology, coastline development and inherited topography. The hypothesis for the evolution of the coastal barrier system of Corrubedo is presented in this study. The Corrubedo coastal barrier has been studied using a variety of methods, including geomorphologic analysis, GPR and coring for mapping sedimentary 3D architecture. Several samples have been dated using OSL and AMS radiocarbon methods to reconstruct the depositional history. Four major phases of sand barrier evolution have been recognized in the southern part of the Corrubedo complex. These phases are characterized by an alternation on the sedimentation between coarse and fine grained deposits. The radiocarbon ages indicate that sedimentation started sometime before 4500 years cal BP. Evidence of a shallow basement were detected in the GPR profiles in Corrubedo which suggests the influence of an antecedent topography on the resultant architecture by: 1) reducing the accommodation space and, therefore its storage capacity, and 2) providing a substratum for the anchoring of the barrier and maintaining a stable shorelin

Predictive Ensemble Maps for cold-water coral distributions in the Cap de Creus Canyon (NW Mediterranean)

Predictive habitat mapping has shown great promise to improve the understanding of the spatial distribution of benthic habitats. However, although they surely represent an important step forward in process-based ecosystem management, their predictive efficiency is not always tested by independent groundtruthing data. This is particularly true for the deep-sea environment, where sample data are always limited compared to the large extent of the areas to be mapped. The aim of this study is to apply and test different spatial models to statistically predict the distribution of three Cold-Water Coral (CWC) species (Madrepora oculata, Lophelia pertusa and Dendrophyllia cornigera) in the Cap de Creus Canyon (NW Mediterranean), based on high-resolution swath-bathymetry data and video observations from the submersible JAGO (IFM-GEOMAR). Submarine canyons act as specific hosting areas for CWCs, owing to their favourable environmental conditions, which provide habitat and shelter for a wide range of species, including commercially viable fish. Maximum Entropy (MaxEnt), General Additive Model (GAM) and decision tree model (Random Forest) were independently applied to represent non-linear species-environment relationships using terrain variables derived from multibeam bathymetry (slope, geomorphologic category, rugosity, aspect, backscatter). Relevant differences between the three models were observed. Nonetheless, the predicted areas where CWCs should be found with higher probabilities coincided for the three methods when a lower spatial scale was considered. According to the models, CWCs are most likely to be found on the medium to steeply sloping, rough walls of the southern flank of the canyon, aligning with the known CWC ecology acquired from previous studies in the area. As a final step, a probabilistic predictive ensemble has been produced merging the outcomes of the three models considered, providing a more robust prediction for the three species. The main insight is that important discrepancies can arise in using different species distribution models, especially when high spatial resolutions are considered. This could in part be the result of the different statistical assumptions behind each of the models. We suggest that a more reliable prediction could be obtained by merging models into spatial ensembles, able to reduce differences and associated uncertainties, showing hence a strong potential as an objective approach in the planning and management of natural resources

Geoheritage as an educational resource and educational resources as heritage

El presente trabajo muestra una compilación de experiencias didácticas que emplean el patrimonio geológico como herramienta pedagógica en la enseñanza de las materias relacionadas con las Ciencias de la Tierra. El objetivo de todas ellas es acercar al alumnado al conocimiento y comprensión de los procesos que acontecen en nuestro planeta, con la finalidad de lograr un acercamiento y sensibilización hacia los mismos. Las seis propuestas seleccionadas presentan variedad en cuanto al contexto territorial de desarrollo de las actividades, a los contenidos y niveles trabajados (desde Enseñanza Secundaria hasta estudios universitarios) y a las metodologías utilizadas para la transmisión de dichos contenidos. Dentro de esta diversidad pueden distinguirse dos grupos de actividades diferentes. El primero de ellos se basa en el desarrollo de experiencias pedagógicas en localidades cuyas características geológicas resultan modélicas, únicas y/o espectaculares. Por el contrario, el segundo conjunto de actividades se centra en el trabajo de los recursos geológicos presentes en el entorno próximo del centro educativo. En ellas se explota su valor patrimonial, es decir, su potencial didáctico para abordar el estudio de la historia geológica del territorio. A través de las actividades incluidas en este compendio, se evidencia la validez de ambos tipos de aproximaciones y, al mismo tiempo, se debaten y realzan algunas de las virtudes más destacables de cada una de ellas. De esta manera, este catálogo podría resultar útil e inspirador para posibles planteamientos futuros.This manuscript presents a compilation of didactic experiences, which address the teaching of Earth Sciences through the knowledge of geological heritage. The aim of these proposals is to promote students’ comprehension of the Earth processes so that they may develop a positive attitude towards them. The six activities chosen offer a catalogue with a variety of sites, methodologies, contents and levels. Within this variety, the activities shown can be gathered into two separate groups. On the one hand, the first group collects experiences, which use geological heritage, i.e., the experiences are developed in places whose geological content is exemplary, unique and/or spectacular. On the other hand, the second group is focused on the geologic resources in the neighborhood of the school. These sites have heritage value, that is, an educational value for studying the geologic history of their territory. The activities drawn together show that both viewpoints are useful, and the benefits of each are pointed out. Consequently, this catalogue might be useful and inspiring for forthcoming attempts in this field