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Living specimens of the amphi-Atlantic asteroid Hacelia superba have been collected in different areas of Gazul mud volcano in the Gulf of Cadiz, south-western Iberian Peninsula, at depths of 380–487 m. This starfish displayed low abundances (~1 ind. 2000 m−2) in beam trawl catches on the mud vulcano and adjacent soft bottoms. The absence of previous records in this area could be due to a low sampling effort on bathyal hard bottoms of the Gulf of Cadiz, especially those of dormant mud volcanoes, as well as a possible misidentification as Hacelia attenuata that also occurs in the area but is restricted to infralittoral and circalitoral bottoms. 0

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Due to growing interest on the Andalusian shore in the culture of the mussel Mytilus galloprovincialis Lamarck, 1819, it is important to identify and establish the main determining factors and criteria to take into account to obtain a positive and well-ordered development of this activity. The entire process needs to respect the availability of natural resources, and environmental protection. Debido al incipiente interés despertado en el litoral de Andalucía por el cultivo de mejillón Mytilus galloprovincialis Lamarck, 1819, surge la necesidad de conocer, identificar y establecer los principales aspectos y criterios a tener en cuenta para el desarrollo ordenado de esta actividad, respetando la disponibilidad de recursos y la protección del medio ambiente. El objetivo de este estudio es, por tanto, conocer los aspectos generales del cultivo de mejillón y estimar la viabilidad del mismo en el litoral andaluz. Instituto Español de Oceanografía

In October 2011, patches of pale-coloured water began appearing off the island’s southern coast, dead fish floated on the ocean surface, and locals noted a strong smell of sulphur in the air. These, it turned out, were the first signs of the first submarine volcanic eruption in the last 500 years of volcanology history of the Canary Islands at 1.8 km south of La Restinga village, some 400 metres below the surface of the Atlantic Ocean. In that moment, the Spanish Institute of Oceanography (IEO) together with both Canary Universities and other research institutions began to monitor the event. The eruption continued until March the following year, leaving the cone of the volcano just 88 metres below the water’s surface. Nowadays, the submarine volcano is still active in a degasification phase with a release of heat, gases and metals that produce significant physical-chemical anomalies in the surrounding waters. The volcano-affected area has exhibited responses that are occurring globally, making El Hierro a unique natural laboratory where the main climate change stressors are acting simultaneously. The results emerging from this volcanic eruption will help to improve the scientific understanding of how future climate change may impact marine biota. On the other hand, we now have the perfect opportunity to find out how the colonization process evolves in a new submarine volcanic habitat, i.e. without any previous inhabiting form of life and in such a young substrate. After the eruption event, new basaltic lava material covered the major part of the sea bottom of “El Mar de Las Calmas”, a Marine Reserve, damaging all previous habitats and living organisms. During my internship I will study and establish the colonization process that took place from 03/2012 to 03/2014 at the submarine volcano, bearing in mind the species diversification among time and place and the physical-chemical and biological conditions that made that possible. In order to do this, underwater visual techniques and dredges were used during three cruises.

We present a morphometric analysis of 41 mounded edifices located on the seafloor to the west of Canary Islands, using a 150 m resolution DEM and very high-resolution seismic profiles. In order to carry out morphometric computation a set of variables (slope, size and shape) were calculated using ArcGIS Analyst tools. A mapping cluster has been generated using Grouping Analyst ArcGIS Statistics toolset where seven differents morphometric groups have been distinguished. Four main types of edifice shapes have been identified within the seven morphometric groups. The first type is a single giant dome elevation that can be considered as an outlier mound. The second type is the most frequent and can be considered as the standard type mound on the Canary continental slope due to its intermediate morphology. They show extrusive seismic characteristics in seismic profiles. The third type is morphologically derived from type 2, representing steeper and higher mounds related with extrusive processes whereas the fourth type represents smoother and flatter mounds related to faulting. This study shows that an elaborated geomorphometry resolves between types of extrusive edifices from those under tectonic conditions Versión del editor

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The mud volcanism in the Iberian and Moroccan margins of the Gulf of Cadiz is well known over more than a decade. Nevertheless, new structures and morphologies related to fluid venting are still discovered in the recent oceanographic cruise SUBVENT2 in 2014 along the Moroccan margin. Four new mud volcanoes have been identified along two sector of Moroccan margin. Two of them in the Eastern Moroccan Margin - EMF (Subvent and Rosco mud volcanoes), located in the upper slope between 350 and 500 m depth. The other two in the Western Moroccan Margin - WMF (Demetrio de Armas and Port Royal), located in the middle slope at 1800 m depth. The main aim of this paper is the morphological characterization of these new mud volcanoes using swath bathymetric data to analyze the relation between tectonic and sedimentary processes with multiparametric sounder and high resolution multichannel seismic profiles. The interpretation of these seismic profiles show that the source of expelled material of mud volcanoes in the EMF is buried under a sedimentary cover of contouritic deposits of 200 m thickness. A high sedimentation rate can cause an increase of pressure that could act as triggered of mud volcano edificies. In the WMF, the new mud volcanoes are developed related to thrust of the Allocthonous Unit of the Gulf of Cadiz. The origin of these structures is mainly related to de NW-SE tectonic compression . Versión del editor

The northeastern sector of the Gulf of Cadiz continental margin has been deeply studied the last two decades. The seafloor is characterized by the Gulf of Cadiz Contourite Depositional System, strong diapirism and seepage related to the mobility of the frontal units of the Gibraltar Arc. Since 2010 high resolution bathymetric data and high and very high resolution seismic reflection and parametric echosounder profiles have improved the resolution of the previous collected data set. These data allow to analyze the middle continental slope morphology and its shallow structure with the aim to know the active tectonic processes on the seafloor. Two types of structures have been considered: (a) anticline domes and (b) normal faults which produce linear scarps and tectonic depressions. The shallow tectonics in this region is mainly related to the high mobility of geological formations in the subsoil and their ductile mechanical behaviour. Versión del editor

The identification and characterization of a series of complex landslides have been carried out using Topographic Parametric Sounder (TOPAS) very high resolution profiles, obtained during the INDEMARES/CHICA1011 and ARSA0313 cruises, along the upper and middle slope of the eastern Gulf of Cádiz continental margin. These landslides constitute a large area of the Upper Quaternary sedimentary deposits in these physiographic domains and are related to active tectonic and diapiric structures along the Upper Quaternary as well as sea-level fall events. The identification of the stratigraphic units has allowed us to obtain the relative age of these gravitational landslides emplacement during the Upper Quaternary. Versión del editor

Technical advances in hydrographic studies of the seafloor and the progressive use of these techniques in oceanographic expeditions with scientific objectives, is generating greater collaborations between the hydrographic and oceanographic institutions. Coordination between the different institutions and the use of IHO criteria in the acquisition of bathymetric data in oceanographic expeditions, allow regional hydrographic offices to have an additional source of data for the improvement of the navigation charts. Meanwhile the Oceanographic Institutions will benefit by having validated bathymetric data of high precision. This product is of great interest in studies of submarine geological hazards where is necessary to have a very detailed knowledge of the seabed to determine possible morphological changes associated with the risk processes and the possible active structures. In addition, monitoring of active volcanoes need to have a good knowledge of changes in the physico-chemical properties of the water column, the possible changes in low intensity emissions (hot water, gas) can be detected with these studies in the overlying water masses. Versión del editor

The Passage of Lanzarote is an example of a wide oceanic corridor. It extends between the eastern Canary Islands and the Western Africa continental margin. Seafloor morphology of this passage has been analyzed with the aim to know the morphogenetic processes related to both the oceanography and the geology. Multibeam bathymetric data and high and very high resolution seismic profiles obtained in the SUBVENT2 cruise have been used. Five main morphological groups were analyzed: (a) Volcanic or diapiric submarine hills; (b) Tectonic features on the continental slope (linear scarps and a rhomboid-like depression) related to normal faults at the top of buried diapirs; (c) Giant circular depressions initially triggered by submarine venting at the top of diapirs; (d) Sedimentary instabilities and canyons (gullies, canyons, mass transport deposits) that are present specially on the Fuerteventura-Lanzarote ridge must be related to the high energy geological processes, both constructive and dismantling, associated to the evolution of these volcanic domains; and (e) Contouritic features both erosive (central channel, contourite channels) and depositional (mounded and plastered drifts) that occur in the central part of the bottom surface of the passage, and are generated by the interaction of the MW and the interface MW-AAIW with the seafloor. Versión del editor

The study of turbidity plumes developed in front of the river mouth, have an increasing scientific interest due to its contribution to infralittoral sediment transport and deposition. River plume evolution and deposition in submarine fans related to environmental constrains could be interpreted by the analysis of suspended particulate matter (SPM) retained during the filtering process. In this study, a new methodology approach to obtain quantitative results in sediment filters, using custom digital image processing techniques, is presented and some promising preliminary results are obtained. This procedure could avoid time-consuming during SPM analysis allowing an easy way to obtain fast and quantitative information, which might lead to a better interpretation and comprehension of factors involved in the evolution of riverine turbidity plumes. Versión del editor

Mud volcanism represents an important migration pathway for methane and other gases from deeper reservoirs to the surface; however most submarine sources remain poor quantified. During SUBVENT2 cruise, water column over several mud volcanoes were surveyed for gas seepage characterization. Water samples of ROV Niskin and Rosette-CTD Niskin bottles were recovered above the Bonjardim, El Cid, Las Negras, Mercator, Algacel, Mvseis, Madrid and Yuma mud volcanoes, and at three newly discovered, mud volcano like structures, to quantify overall gases release fluxes from seabed. CO2 and CH4 concentrations were measured by potentiometric titration and using a gas chromatograph, respectively, in order to understand the relationship between physicochemical and geological processes. Gases concentrations decreased from shallower to deeper mud volcanoes. Values varied widely within 50 to 200 nM for CH4 and between 400 to 1500 μatm for fCO2. Greenhouse gases variations were large influenced by water column depth, temperature, salinity and possibly by anaerobic oxidation of methane (AOM). Our observations suggest that the emission of methane and carbon dioxide from the mud volcanoes structures studied here may be relevant at the present as a part of the carbon global cycle. Versión del editor

The Madeira Island lower slope has been build-up mostly by along slope-processes associated with mass movement deposits as seen in GEBCO bathymetry, multibeam bathymetry, Parasound echosounder profiles and multichannel seismic reflection profiles. A plastered contourite drift (Madeira Drift) developed on this lower slope, being composed of seismic units D1, D2 and D3. The most probable water mass responsible for its deposition is the Antarctica Bottom Water (AABW). The youngest sediments of seismic units D2 and D3 are affected by gravity-driven processes, probably slumps and debris flows, which moved downslope towards west. Parasound profiles show evidences of such mass movements on present-day seabottom (e.g. diffraction hyperbolae echoes) but also of past-events buried within the contourite sediments. These older debris flows are recognized by semitransparent/transparent acoustic facies and lenticular shape. Versión del editor

Several morphosedimentary signatures produced by the interaction between alongslope and downslope sedimentary processes have been identified in the Pliocene and Quaternary records as well as on the present-day seafloor of the Alboran Sea. The scenarios of interaction move between two-end-members: from bottom currents dominating gravity flows to gravity flows dominating contour currents. In between these extreme cases, the alternation and balancing of both processes can occur; bottom current activity influencing the gravity flows has been also detected. Although interaction occurs in the Spanish and Moroccan margins, it is especially complex and varied on the Spanish margin, with regional and local effects on the turbidite systems. In contrast, the interaction on the Moroccan margin primarily inhibits the formation of canyons and related fan lobe deposits. Versión del editor

The construction and evolution of submarine deltaic deposits are influenced by a combination of allogenic and autogenic factors. Numerical simulation of turbidity currents are used to propose a morphodynamic model that quantifies the effect of the slope and river input variations on delta development/construction for the case of mountainous rivers subjected to a seasonal Mediterranean climate, such as those located in the northern shelf of the Alboran Sea. These simulations were performed by using both constant and variable rates of fluvial flows. Both theoretical and real bathymetric profiles were used in the simulations. The results indicate that both the river flow and the depositional basin slope are key features for the development of morphostratigraphic features of submarine deltas at different spatial scales. Versión del editor

The continental slope of the Canary Islands volcanic province is characterized by the occurrence of several seamounts and large landslides that have been widely documented. A detailed morphological study of the Echo seamount has been done by using multibeam bathymetry, backscatter data and very high resolution seismic profiles. The seamount shape, the occurrence of a flat summit and the presence of characteristics morphological features on the summit and along the flanks as volcanic cones, ridges, slides scars, gullies and channels, among others, have allowed establishing differences in its evolution. The analysis of these seamount features let to think that the seamount could be an oceanic island that becomes eroded and sank to its present depth. Recent geological processes observed at the base of the seamount let to establish different features and morpho-sedimentary units. They have been interpreted as the result of dismantling processes of the flanks although they have also related to the massive slope instabilities developed on the continental slope. Versión del editor

The evolutionary stages of the submarine delta off the Adra River are investigated in this study, under the context of climatic fluctuations entangled with increasing human activities and interventions in the drainage basins and adjacent shores during the Middle to Late Holocene. To achieve that goal, we used an extensive database comprising a set of bathymetric data covering different time slices, a dense grid of high-resolution seismic data and several sediment cores collected in the two submarine lobes of the Adra River delta. Two main evolutionary phases can be identified. The first one extended through most of the construction history and was mediated by major climatic events at the Mediterranean scale; this phase included three major progradational events occurring during the Mid Holocene, the Roman time and the Little Ice Age. The most recent phase is strongly determined by human modifications of the fluvial channels, and resulted in a drastic transformation of the submarine sedimentary environment. Versión del editor

Clinoforms constitute the basic building elements of continental margin growth. Submarine clinoforms are composed of three geometric elements: topset, foreset and bottomset. This study focuses on the determination of the distal termination of submarine deltaic clinoforms by using morphometric criteria and subsequent validation with stratigraphic, sedimentological and geochemical data. The mechanism and factors that potentially affect bottomset generation are also discussed. These criteria have been applied to the Guadalhorce River prodelta, an environment where advection and along-shore sediment transport prevail. We conclude that the seaward advance of the prodelta is prevented by the current velocity increase at the foot of the morphosedimentary feature. En prensa

Extrusive edifices and structural reliefs, catalogued as mounds and located on the seafloor to the west of Canary Islands were analyzed by acoustic data obtained with multibeam and parametric echosounders during several oceanographic expeditions. They were carried out at deep waters, from 4800 to 5200 m, and they have allowed characterizing 41 newly discovered submarine structures which occur either as isolated edifices or clustered mounds. These features have circular to elongated shapes with diameters of 2-24 km and relief heights of 10 to 250 m, showing different flank slopes of 2-50°. They generally display mounded forms and show morphological elements as ridges, near-circular rock outcrops, depressions and fault scarps together with mass flow and slide deposits located at the vicinity of the edifices. Two types of extrusive features are evidenced by the morphological and seismic data analyses, the first one probably corresponds to high velocity extrusions that reach the seafloor surface and the second one is probably formed by the combination of faulted structures and low velocity extrusions that produce singular domes in the shallower sedimentary records. Based on both analyses, extrusive phenomena represent the dominant mechanism for mound field evolution in the Canary lower slope region. Versión del editor

This work presents results from bioturbation intensity and trace fossil analysis of the piston core PC07, recovered at Portimão Bank during the MONTERA cruise in 2012. The aim was to investigate the potential of bioturbation analysis as an indicator for mass movement events. Bioturbation and trace fossil identification was complemented with results from sedimentological analysis (grain-size, carbonates, organic matter), measurements of magnetic fabric parameters (mass magnetic susceptibility and anisotropy of magnetic susceptibility), and AMS 14C dating. Considering the vertical zonation of bioturbation, magnetic fabric changes, sedimentology and AMS radiocarbon dating, two intervals were identified, Interval A (0-180 cm) and Interval B (180-356 cm), being the limit between them placed at 180-181cm. These intervals seem to replicate almost the same vertical zonation of bioturbation and the trend of carbonates and organic matter changes downcore. The magnetic fabric parameters (degree of anisotropy – Pj and shape – T of the magnetic susceptibility ellipsoid) show the major change at about 180 cm. Geochronological results indicate that the age of sediments in Interval A is 8590 yr BP (31-32 cm) and 14 300 yr BP (103-104 cm). Otherwise, ages in Interval B are the following: 5035 yr BP (181-182 cm), 8900±50 yr BP (219-220 cm), 18999±120 yr BP (303-305 cm). These results point to the emplacement of sediments of Interval A on top of youngest sediments of Interval due to landsliding. Since no internal deformation is seen, probably this indicates translational movement and short transport from the source. Versión del editor

Contourite drifts are one the main morphosedimentary features in the Alboran Sea and their sediments are important archives of the past oceanographic conditions and sedimentary processes. The end-member modelling approach lets to decompose multimodal grain-size distribution into genetically meaningful subpopulation that may be related to different sediment transport mechanisms and source areas. Three end-members have been identified in the contourite drift and moat system located at the southern side of the Dijbouti Ville seamount that have been interpreted in terms of sediment sources. Two end-members point to an eolian source and comprise fine silt (EM1) and coarse silt (EM2) as modal grain-sizes, characterized by high and low contents, respectively, of terrigenous elements (Al, Si, Ti and K). The third end-member (EM3) indicates a fluvial origin and is mainly defined by a clay modal grain-size of intermediate and homogeneous content in terrigenous elements. Downcore variation of the relative proportion of these EMs can be used to decipher paleocenographic and paleoclimatic conditions in the Alboran Sea. Versión del editor

New high-quality high-resolution bathymetric data along the northeastern slope of the Gulf of Cadiz continental margin reveals three gullies fields. The morphological and morphometric features of these gullies have been studied. The following morphometric variables have been measured in every gully in order to make a quantitative morphological analysis: width, depth, thalweg length, straight line length, area, sinuosity index, width/depth ratio, and stream order. The morphological characterization of the gullies suggests that these morphologies vary with the local physiography (concavity/convexity of the slope), the sediment transport efficiency, tectonic control and oceanographic regime. Versión del editor

The Guadalfeo and the Adra submarine deltas off the northern coast of the Alboran Sea have been built up under the direct influence of short and mountainous rivers. The area is subjected to strong climatic seasonality, with sporadic winter torrential floods and high summer aridity. In addition numerous anthropogenic activities have affected these systems, mostly during the last two centuries. In order to decode the influence of climatic variability and anthropogenic impacts on sediment supplies during the recent past, five sediment cores were collected from the Guadalfeo and Adra submarine deltas. Benthic foraminiferal and sedimentological analyses, combined with radiocarbon dating, were performed. The impact of torrential floods alternating with periods of low rainfall or dry periods were recorded in the Adra and Guadalfeo prodeltas. Periods with low abundance of benthic foraminifera and high amounts of coarse-grained sediments, were interpreted as the result of enhanced sediment supply to the shelf triggered by major flood events. On the other hand, periods with high amounts of fine-grained sediments and high abundances of colonizers and opportunistic foraminiferal species indicate the establishment of new environments with distinct ecological constraints. These environments were driven by lower sediment supplies during low rainfall or dry periods. The most recent sedimentation seems to reflect the human interventions in the rivers basins, such as deviation of the main river courses and dams construction, which reduced the sediment input and promoted the deposition of shallow-water submarine deltas. Versión del editor

Five different groups of gullies have been distinguished along the northeastern slope of the Gulf of Cádiz using geostatistical analysis. A Grouping Analyst has been carried out to six morphological variables of the gullies: area, straight line length, width/depth ratio, width, depth and stream order. The spatial distribution of the identified five groups and their mean characteristics have allowed us to propose an evolutionary model for the two zones of the upper continental slope. This model is related to the local physiography, the sediment supply, the tectonic control and the oceanographic regime. Versión del editor

The Diego Cao channel is located on the central-north middle slope of the Gulf of Cadiz. It separates the Bartolomeu Dias and Faro sheeted drift plateaus to the north of the Guadalquivir Bank margin uplift. A striking linear series of circular depressions occur parallel to the channel on the Bartolomeu Dias sheeted drift (western channel flank), while a remarkable amphitheater-shaped escarpment affects the channel eastern flank. Their morphological and high- and medium-resolution stratigraphic analysis allows inferring their origin as the result of a complex interplay between oceanographic (bottom currents), mass-wasting and tectonic processes. All features seem to have a common origin, related to an especially active tectonic phase during the Mid-Pleistocene, probably related to adjustments of the deep structural features. Since then, the action of the bottom currents and the local influence of structural processes have shaped the present-day topography. The Diego Cao channel is re-interpreted as a contourite moat associated to a complex mounded, separated drift that includes the circular depressions. They result from contourite deposition over the erosional surface originated by widespread mass-wasting events during the Mid-Pleistocene. Versión del editor

VIII Simposio sobre el Margen Ibérico Atlántico (MIA15), del 21 al 23 de septiembre de 2015, Málaga.-- 4 pages, 2 figures, The Diego Cao channel is located on the central-north middle slope of the Gulf of Cadiz. It separates the Bartolomeu Dias and Faro sheeted drift plateaus to the north of the Guadalquivir Bank margin uplift. A striking linear series of circular depressions occur parallel to the channel on the Bartolomeu Dias sheeted drift (western channel flank), while a remarkable amphitheater-shaped escarpment affects the channel eastern flank. Their morphological and high- and medium-resolution stratigraphic analysis allows inferring their origin as the result of a complex interplay between oceanographic (bottom currents), mass-wasting and tectonic processes. All features seem to have a common origin, related to an especially active tectonic phase during the Mid-Pleistocene, probably related to adjustments of the deep structural features. Since then, the action of the bottom currents and the local influence of structural processes have shaped the present-day topography. The Diego Cao channel is re-interpreted as a contourite moat associated to a complex mounded, separated drift that includes the circular depressions. They result from contourite deposition over the erosional surface originated by widespread mass-wasting events during the Mid-Pleistocene, This research is part of the projects MONTERA (CTM-14157-C02-02) and MOWER (CTM-2012-395599-C03) funded by the Spanish Ministry of Economy and Competitivity. The research of Marga Garcia has been funded by a Juan de la Cierva and a Talentia Grant (Ref. 267226)

VIII Simposio sobre el Margen Ibérico Atlántico (MIA15), del 21 al 23 de septiembre de 2015, Málaga.-- 4 pages, 5 figures, This work presents results from bioturbation intensity and trace fossil analysis of the piston core PC07, recovered at Portimão Bank during the MONTERA cruise in 2012. The aim was to investigate the potential of bioturbation analysis as an indicator for mass movement events. Bioturbation and trace fossil identification was complemented with results from sedimentological analysis (grain-size, carbonates, organic matter), measurements of magnetic fabric parameters (mass magnetic susceptibility and anisotropy of magnetic susceptibility), and AMS 14C dating. Considering the vertical zonation of bioturbation, magnetic fabric changes, sedimentology and AMS radiocarbon dating, two intervals were identified, Interval A (0-180 cm) and Interval B (180-356 cm), being the limit between them placed at 180-181cm. These intervals seem to replicate almost the same vertical zonation of bioturbation and the trend of carbonates and organic matter changes downcore. The magnetic fabric parameters (degree of anisotropy – Pj and shape – T of the magnetic susceptibility ellipsoid) show the major change at about 180 cm. Geochronological results indicate that the age of sediments in Interval A is 8590 yr BP (31-32 cm) and 14 300 yr BP (103-104 cm). Otherwise, ages in Interval B are the following: 5035 yr BP (181-182 cm), 8900±50 yr BP (219-220 cm), 18999±120 yr BP (303-305 cm). These results point to the emplacement of sediments of Interval A on top of youngest sediments of Interval due to landsliding. Since no internal deformation is seen, probably this indicates translational movement and short transport from the source, This work was supported by MONTERA (CTM2009-14157-C02-MONTERA) and MOWER (CTM2012-39599-C03-02) projects

This study reports the benthic megafauna that inhabit the coast of Huelva where the wedge clam fishery is carried out with hand dredges. Samples were collected seasonally using a specially designed hand dredge similar to that used by local fishermen but with a smaller mesh size bag (3 mm x 3mm). 35 georeferenced transects were performed using a GPS device to standardize data to swept area. A total of 45918 individuals with a biomass of 52799 g were obtained. An inventory of 32 species belonging to 5 phyla was identified from February to November 2014 in these fishing areas. In relation to the number of species and biomass, the Mollusca phylum was the most abundant group followed by Arthropoda. The most dominant bivalve mollusc was Donax trunculus (84%), followed by Mactra stultorum and M. glauca. The frequency index of D. trunculus was 100% for each season, and maximum values of abundance and biomass were observed in spring and summer. Versión del editor

The Guadalfeo and the Adra submarine deltas off the northern coast of the Alboran Sea have been built up under the direct influence of short and mountainous rivers. The area is subjected to strong climatic seasonality, with sporadic winter torrential floods and high summer aridity. In addition numerous anthropogenic activities have affected these systems, mostly during the last two centuries. In order to decode the influence of climatic variability and anthropogenic impacts on sediment supplies during the recent past, five sediment cores were collected from the Guadalfeo and Adra submarine deltas. Benthic foraminiferal and sedimentological analyses, combined with radiocarbon dating, were performed. The impact of torrential floods alternating with periods of low rainfall or dry periods were recorded in the Adra and Guadalfeo prodeltas. Periods with low abundance of benthic foraminifera and high amounts of coarse-grained sediments, were interpreted as the result of enhanced sediment supply to the shelf triggered by major flood events. On the other hand, periods with high amounts of fine-grained sediments and high abundances of colonizers and opportunistic foraminiferal species indicate the establishment of new environments with distinct ecological constraints. These environments were driven by lower sediment supplies during low rainfall or dry periods. The most recent sedimentation seems to reflect the human interventions in the rivers basins, such as deviation of the main river courses and dams construction, which reduced the sediment input and promoted the deposition of shallow-water submarine deltas.

The construction and evolution of submarine deltaic deposits are influenced by a combination of allogenic and autogenic factors. Numerical simulation of turbidity currents are used to propose a morphodynamic model that quantifies the effect of the slope and river input variations on delta development/construction for the case of mountainous rivers subjected to a seasonal Mediterranean climate, such as those located in the northern shelf of the Alboran Sea. These simulations were performed by using both constant and variable rates of fluvial flows. Both theoretical and real bathymetric profiles were used in the simulations. The results indicate that both the river flow and the depositional basin slope are key features for the development of morphostratigraphic features of submarine deltas at different spatial scales.

Population structure, growth and production of the wedge clam Donax trunclus, inhabiting highly exposed sandy beaches of the littoral of Huelva (SW Spain) were investigated between January 2014 and July 2015. Growth rates were estimated comparing two different methods in the intertidal zones of beaches: (i) length-frequency distributions (LFD) analysis in two separated beaches (Doñana and Isla Canela) (ii) internal shell growth bands by thin shell cross sections (TS). For the TS methodology, valves were embedded in methyl-methacrylate, and sequential sections were grounded and polished to a thickness of 80-100 µm. This technique allowed the identification of annual ring depositions and the shell length-age keys were performed. In addition, several deformities (related to environmental stress or damages probably caused by fishing gears) as well as signs or recovery were observed. Both methodologies were equally appropriate to estimate growth of D. trunculus. Von Bertalanffy growth functions were established from LFD and TS using an asymptotic length (L∞) of 44.8 mm and the growth constants (K) of 0.5 (LF) and 0.44 yr-1 (TS). The intertidal biomass of D. trunculus ranged between 3.03-3.31 g ash-free dry mass (AFDW) m-2 yr-1. Individual production revealed the highest value at 27 mm length (0.117 g AFDW m-2 yr-1) and annual production ranged between 3.40 and 4.91g, resulting in renewal rate values (P/B) between 1.03 y 1.61. Differences between beaches in terms of annual production and P/B seem to be partially related to human activities. Versión del editor

The REMALA Project studied the spatial and temporal distribution of the larval fish assemblage over an annual cycle, in the bay of Malaga (Northwest Alboran Sea). More than 80 larval fish taxa were identified in the study area highlight its high biodiversity, jointly with the presence of larvae of species with a high commercial interest, such as e.g. Sardina pilchardus, Engraulis encrasicolus or Pagrus pagrus. The larval fish assemblage in the bay of Malaga appears to be a relatively stable community with some intra-annual and onshore-offshore variability.

The northeastern sector of the Gulf of Cadiz continental margin has been deeply studied the last two decades. The seafloor is characterized by the Gulf of Cadiz Contourite Depositional System, strong diapirism and seepage related to the mobility of the frontal units of the Gibraltar Arc. Since 2010 high resolution bathymetric data and high and very high resolution seismic reflection and parametric echosounder profiles have improved the resolution of the previous collected data set. These data allow to analyze the middle continental slope morphology and its shallow structure with the aim to know the active tectonic processes on the seafloor. Two types of structures have been considered: (a) anticline domes and (b) normal faults which produce linear scarps and tectonic depressions. The shallow tectonics in this region is mainly related to the high mobility of geological formations in the subsoil and their ductile mechanical behaviour.

The evolutionary stages of the submarine delta off the Adra River are investigated in this study, under the context of climatic fluctuations entangled with increasing human activities and interventions in the drainage basins and adjacent shores during the Middle to Late Holocene. To achieve that goal, we used an extensive database comprising a set of bathymetric data covering different time slices, a dense grid of high-resolution seismic data and several sediment cores collected in the two submarine lobes of the Adra River delta. Two main evolutionary phases can be identified. The first one extended through most of the construction history and was mediated by major climatic events at the Mediterranean scale; this phase included three major progradational events occurring during the Mid Holocene, the Roman time and the Little Ice Age. The most recent phase is strongly determined by human modifications of the fluvial channels, and resulted in a drastic transformation of the submarine sedimentary environment.

VIII Simposio sobre el Margen Ibérico Atlántico (MIA15), del 21 al 23 de septiembre de 2015, Málaga.-- 4 pages, 4 figures, Contourite drifts are one the main morphosedimentary features in the Alboran Sea and their sediments are important archives of the past oceanographic conditions and sedimentary processes. The end-member modelling approach lets to decompose multimodal grain-size distribution into genetically meaningful subpopulation that may be related to different sediment transport mechanisms and source areas. Three end-members have been identified in the contourite drift and moat system located at the southern side of the Dijbouti Ville seamount that have been interpreted in terms of sediment sources. Two end-members point to an eolian source and comprise fine silt (EM1) and coarse silt (EM2) as modal grain-sizes, characterized by high and low contents, respectively, of terrigenous elements (Al, Si, Ti and K). The third end-member (EM3) indicates a fluvial origin and is mainly defined by a clay modal grain-size of intermediate and homogeneous content in terrigenous elements. Downcore variation of the relative proportion of these EMs can be used to decipher paleocenographic and paleoclimatic conditions in the Alboran Sea, This research has been supported by MONTERA (CTM2009-14157-C02) and MOWER (CTM2012-39599-C03) projects of the MINECO

El objetivo del Proyecto INDEMARES/CHICA es realizar un inventario de los hábitats relacionados con la expulsión de metano (1180) en el Golfo de Cádiz. Anteriores a esta campaña, se han realizado tres expediciones: la primera, INDEMARES CHICA-0610, se centró en la búsqueda de escapes de fluidos en las zonas someras (plataforma e infralitoral distal); la segunda, INDEMARES CHICA-0211, prospectó los puntos de emisión identificados en los estudios geológicos antecedentes (volcanes de fango, depresiones de colapso), y en la tercera, INDEMARES CHICA-1011, se realizó una batimetría y transectos de TOPAS en el borde de la plataforma y talud superior del Golfo de Cádiz. Además, se añadieron unos barridos con cámara fotográfica y de video submarino, con el fin de reconocer el fondo del mar en los volcanes más someros (Albolote y Gazul). En esta cuarta campaña, INDEMARES CHICA-0412, se ha tratado de completar la información sedimentológica y de fauna bentónica mediante muestras de draga Box-Corer, se han realizado transectos de video y fotografía submarina, y se han obtenido datos de ecosonda multihaz, EK60, y TOPAS de la zona de los volcanes de fango. FUNDACIÓN BIODIVERSIDAD, INSTITUTO ESPAÑOL DE OCEANOGRAFIA