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Since 2004, high resolution profiles of the 3D velocity of the water column have been collected at the westernmost sill of the Strait of Gibraltar (Espartel Sill), with the aim of monitoring the Mediterranean water outflow and evaluate its short and long term variability. A 75 kHz up-looking Acoustic Doppler Profiler (ADP) and, more recently, another 500 kHz model installed in down-looking mode, have been embedded in a subsurface buoy, deployed ∼20m above the seafloor at a depth of approximately 360m. The averaged profile of the observed along-strait current uses to show local minima ∼50m above seafloor, which has been interpreted as the diurnal-semidiurnal interaction of tidal currents (Sammartino et al., 2015). The prevailing semidiurnal tide drives periodic accelerations of the westward Mediterranean current flowing at the bottom, whereas diurnal constituents slow them down, giving rise to a local minimum in amplitude, and prompting severe drops in measurements accuracy. In year 2019, the main ADP was replaced by a 100 kHz model sporting an additional vertical beam that collects high resolution echograms of the water column. This new information reveals the key role of scatterers concentration, which undergoes diel migrations, and affects the reliability of the velocity observations which rely on the amplitude of scattered echo recorded by the instruments. Actually, echo amplitude reaches average correlations of 0.7 with measurement uncertainties. In light of these new insights, an accurate update of the Mediterranean outflow calculations is performed and new values of trend and long-term variability, are estimated. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

4 pages, 5 figures.-- Correction Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean; Proceedings of the National Academy of Sciences of the USA 117(36): 22281-22292 (2020); doi: 10.1073/pnas.1918943117; http://hdl.handle.net/10261/221953, The authors wish to note the following: “This study’s seawater Sr:Ca values were systematically low as a consequence of normalization to another published low value for the International Association for the Physical Sciences of the Oceans (IAPSO) (1). IAPSO has been used at the Ocean Drilling Program, Texas A&M University (ODP-TAMU) (http://www-odp.tamu.edu/), and is still being used as the primary standard for elemental composition of seawater/interstitial water. Consequently, our seawater value of Sr:Ca = 8.28 mmol:mol was systematically low by approx. 3.70%, if we accept seawater Sr:Ca 8.60 mmol:mol as the recommended value for IAPSO North Atlantic surface water salinity standard. The uncertainty budget should be expanded including the uncertainty of IAPSO composition. The largest contribution to expanded uncertainty of our data comes from the uncertainty of the IAPSO reference composition, which is 3.29% using all published values. This will result in 3.30% (1 SD) expanded uncertainty for seawater Sr:Ca (and 0.5%, for seawater Mg:Ca) of the entire data set with respect to accuracy. We have corrected all seawater Sr:Ca values with a factor of 1.0243 in all our tables (e.g., SI Appendix, Table S1 averages) and in the figures (Fig. 4, Fig. 5), where a ratio was used. Note that the seawater Sr:Ca % changes are small, thus changes are hardly noticeable on large displays (e.g., Figures), but they can be seen in the tables and averages/SD calculations. Seawater Sr:Ca ratios are also corrected in the main text where relevant

Text Abstract, Series Temporales de datos Oceanográficos en el golfo de CAdiz, STOCA

The Daily Egg Production Method (DEPM) to estimate the Anchovy Spawning Stock Biomass (SSB) in the Gulf of Cádiz (ICES, Subdivision 9a South) is conducted by Spain (Centro Nacional Instituto Español de Oceanografía, CSIC) every three years, since 2005. BOCADEVA 0720 is the sixth survey of the historical DEPM series for anchovy in the Gulf of Cádiz and was delivered on board R/V Ramón Margalef (CNIEO) from the 9th to the 17th of July 2020. The surveyed area extended from Strait of Gibraltar to Cape San Vicente (Spanish and Portuguese waters in the Gulf of Cadiz). Plankton samples, along a grid of 21 transects perpendicular to the coast were obtained for the spawning area delimitation and density estimation of the daily egg production. The survey objectives also included the characterization of the oceanographic and meteorological conditions in the study area. The samples to estimate adult parameters (sex ratio, female mean weight, batch fecundity and spawning fraction) were obtained in the acoustic survey “ECOCADIZ 2020-07”, carried out during the same period. This working document provides a d escription of the survey, laboratory analysis and estimation procedures used to obtain the Gulf of Cadiz Anchovy SSB by DEPM for 2020 in the South-Atlantic Iberian Stock.

Spatiotemporal variations of the partial pressure of CO2 (pCO2) were studied during 8 oceanographic cruises conducted between March 2014 and February 2016 in surface waters of the eastern shelf of the Gulf of Cádiz (SW Iberian Península) between the Guadalquivir River and Cape Trafalgar. pCO2 presented a range of variation between 320.6 and 513.6 µatm, with highest values during summer and autumn and lowest during spring and winter, showing a linear dependence between pCO2 and temperature. The distributions of pCO2 were not homogeneous. Spatially, there was a general decrease from coastal to off-shore stations associated with continental inputs and presented an increase in the zones deeper than 400 m due to the influence of the eastward branch of the Azores Current. On the other side, the study area acted as source of CO2 to the atmosphere during summer and autumn and as a sink in spring and winter, with a mean value for the study period of −0.18 ± 1.32 mmol m−2 d−1. In the Guadalquivir and Sancti Petri sections, the CO2 fluxes decreased towards offshore, whereas in the Trafalgar section increased due to the presence of an upwelling. These results highlighted the Gulf of Cádiz as a CO2 sink, with a capture capacity of 14.9 Gg year−1.

International Estuarine Biogeochemistry Symposium, Vigo (Spain), 4-5th June 2019, This study aims to analyze long-term dissolved O2 (DO) trend in the NW Iberian coastal upwelling system in order to better understand physical and biological processes affecting biogeochemical characteristics of the subsurface Eastern North Atlantic Central Waters (ENACW). A high-quality 43 yr (1970-2013) data set collected at the 27.1 isopycnal level (representative of ENACW) from an area between 41º-43ºN and 9º-11ºW was analyzed. Since the seventies, subsurface DO levels declined with a rate of 0.39 μmol O2 Kg-1 yr-1 despite no sustained decrease trend through time was registered for temperature and salinity. DO tendency to drop ran in parallel with significant increments of both sea surface temperature (SST) and subsurface apparent oxygen utilization (AOU) annual means, pointing to the increase in the subsurface waters residence time as responsible for the deoxygenation processes registered in the study area. Moreover, natural decadal variability of both thermohaline properties and DO annual mean concentrations at the ENACW isopycnal level agreed with changes in the North Atlantic Oscillation (NAO) index. In this regard, we can state that overprinted to the last 40-yr DO decreasing trend observed in the NW Iberian coastal upwelling system, natural subsurface waters oxygenation may have occurred when high positive NAO phases promote the strengthening and eastward expansion of the subpolar gyre, bringing cooler and more oxygenated conditions to the study area, This presentation is a contribution of the project ‘i-SMALL: Importancia de lo pequeño en un océano en cambio: desentrañando la variabilidad de corta escala y el papel del plancton pequeño’ funded by Spanish Ministry of Science and Innovation (CTM2014-56119-R).

Spatio-temporal variations in the partial pressure of CO2 (pCO2) were studied during eight oceanographic cruises conducted between March 2014 and February 2016 in surface waters of the eastern shelf of the Gulf of Cádiz (SW Iberian Peninsula) between the Guadalquivir river and Cape Trafalgar. pCO2 presents a range of variation between 320.6 and 513.6 µatm with highest values during summer and autumn and lowest during spring and winter. For the whole study, pCO2 shows a linear dependence with temperature, and spatially there is a general decrease from coastal to offshore stations associated with continental inputs and an increase in the zones deeper than 400 m related to the influence of the eastward branch of the Azores Current. The study area acts as a source of CO2 to the atmosphere during summer and autumn and as a sink in spring and winter with a mean value for the study period of −0.18±1.32 mmol m−2 d −1 . In the Guadalquivir and Sancti Petri transects, the CO2 fluxes decrease towards offshore, whereas in the Trafalgar transect fluxes increase due to the presence of an upwelling. The annual uptake capacity of CO2 in the Gulf of Cádiz is 4.1 Gg C yr−1 ., Sí

European Geosciences Union (EGU) General Assembly 2018, 8-13 April 2018, Vienna, Austria.-- 1 page, The pathways and transformations of dense water overflows, which depend on small-scale interactions between flow dynamics and erosional-depositional processes, are a central piece in the ocean’s large-scale circulation. A novel, high-resolution current and hydrographic data set highlights the intricate pathway travelled by the saline Mediterranean Overflow as it enters the Atlantic. Interaction with the topography constraints its spreading. Over the initial 200 km west of the Gibraltar gateway, distinct channels separate the initial gravity current into several plunging branches depth-sorted by density. Shallow branches follow the upper slope and eventually detach as buoyant plumes. Deeper branches occupy mid slope channels and coalesce upon reaching a diapiric ridge. A still deeper branch, guided by a lower channel wall marked by transverse furrows, experiences small-scale overflows which travel downslope to settle at mid-depths. The Mediterranean salt flux into the Atlantic has implications for the buoyancy balance in the North Atlantic. Observations on how this flux enters at different depth levels are key to accurately measuring and understanding the role of Mediterranean Outflow in future climate scenarios

Poleward undercurrents are well known features in Eastern Boundary systems. In the California Current Eastern Boundary upwelling system (CalCEBS) the California poleward undercurrent has been widely reported, and it has been demonstrated that it transports nutrients from the equator waters to the northern limit of the subtropical gyre. However, in the Canary Current Eastern Boundary upwelling system (CanCEBS), the Canary deep poleward undercurrent (CdPU) has not been properly characterized. In this study, we use trajectories of Argo floats and model simulations to properly characterize the CdPU, including its seasonal variability, and the driving mechanism. The Argo observations show that the CdPU flows from 20oN, near cape Blanc, to, approximately, 45oN, near cape Finisterre in the northwest Spanish’s coast. The CdPU flows deeper than the CalUC, and its mean depth varies with latitude, from the surface at 20oN to 900 m at 44oN. The CdPU shows a marked seasonal variability, with it maximum strength in fall, and the minimum in spring.

Trabajo presentado en el XVIII Seminario Ibérico de Química Marina, celebrado en Alicante (España) de 20 al 22 de julio de 2016., Dissolved organic matter (DOM) is a major component of the organic matter transported to the coastal zone by rivers. It controls ecosystem-level processes (e.g. food web) and constitutes an important pathway for nutrients transport from land to coastal waters. We know that estuarine discharges affect the primary production and nutrient composition in the adjacent coastal area. For instance, the current hypernutrification of the Guadalquivir estuary may benefit primary production on adjacent coasts. However, studies on DOM in the Gulf of Cádiz waters are unknown despite its importance in the global ocean functioning. The Gulf of Cádiz is under the estuarine influence of three main estuaries: Guadiana, Tinto-Odiel and Guadalquivir. The present study evaluates the relevance of DOM and the estuarine influence and environmental factors which determine its distribution in the Gulf of Cádiz. Our results suggest that the Gulf of Cádiz water mass is receiving large amounts of dissolved organic transported by the Guadiana and Guadalquivir rivers and much lesser from Tinto-Odiel. Thus, the estuarine influenced area explained the fDOM variability in the Gulf of Cadiz and this variability was shaped by turbidity, water depth and distance from the coast. Within the estuarine ecosystems, salinity and turbidity were the main factors explaining the fDOM variability., This work was financed by the MICCIN grants DILEMA (CTM2014-59244-C3-2-R).

Almost ten year of Acoustic Doppler Current Profiler (ADCP) observations collected at the westernmost sill (Espartel sill) of the Strait of Gibraltar by a monitoring station, first installed in year 2004, have been carefully processed to provide the most updated estimation of the outflow of Mediterranean water through the Strait. A comprehensive quality control of the factors affecting the uncertainty of the measurements has been carried out and a great care has been paid to infer the current at the bottom layer, where direct observations are lacking. The mean outflow in the southern channel of the sill section, where the monitoring station is installed, has been estimated as 0.82 Sv (1 Sv = 1x10^6 m^3/s), with an average contribution of the eddy fluxes of 0.04 Sv. This figure is an overestimation, as the vertical profile at the mooring site was assumed valid for the whole section, thus ignoring the lateral friction. On the other hand, it only gives the flow through the south channel and disregards the fraction flowing through shallower north part. Both drawbacks have been addressed by investigating the crossstrait structure of the outflow from hindcasts produced by the MITgcm numerical model, which was run in a highresolution domain covering the Gulf of Cádiz and Alboran Sea basins. An overall rectifying factor of 1.039 was found satisfactory to correct the first estimate, so that the final mean outflow computed from this dataset is 0.85 Sv, which is complemented with an uncertainty of ±0.03 Sv based on the interannual variability of the series. The time analysis of the series shows an outflow seasonality of around the 8% of the mean value, with maximum outflow in early spring. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

Trabajo presentado en ECSA 56 (Unbounded boundaries and shifting baselines: estuaries and coastal seas in a rapidly changing world), celebrado en Londres del 6 al 9 de septiembre de 2015.

This working document provides a brief description of the survey, laboratory analysis and estimation procedures used to obtain the Gulf of Cadiz anchovy SSB by DEPM for 2014 in the South-Atlantic Iberian Stock. Results are preliminary, because the estimation of the spawning fraction is not available yet.

Se integra información hidrográfica, geomorfológica, sedimentológica y biológica, para la caracterización de los ecosistemas marinos en el punto de vertido y área adyacente previa al inicio de las obras de dragado del Puerto de Maó., RESUMEN: En este documento se presentan los trabajos científicos realizados por el Instituto Español de Oceanografía, dentro del Plan de Vigilancia Ambiental del dragado del Puerto de Maó (Menorca, Islas Baleares), para la caracterización de los ecosistema marino en el punto de vertido y área adyacente, previa al inicio de las obras. Se incluyen los resultados y las conclusiones de los estudios realizados por diversos grupos de investigación, principalmente en Enero-Marzo 2014, en relación al fondo marino, la hidrodinámica, las praderas de Posidonia oceanica y el molusco bivalvo Pinna nobilis, el macro-bentos de los fondos circalitorales blandos y los contaminantes en agua, sedimentos y biota, así como en especies de interés comercial para el consumo humano. Este informe se contempla en el contrato entre la Autoridad Portuaria de Baleares y el Instituto Español de Oceanografía, suscrito el 5 Febrero 2014, para los trabajos de asistencia técnica para la revisión y control del Plan de Vigilancia Ambiental del dragado del Puerto de Maó., RESUM: En aquest document es presenten els treballs científics realitzats per l’Instituto Español de Oceanografía, dins del Pla de Vigilància Ambiental del dragat del Port de Maó (Menorca, Illes Balears), per a la caracterització dels ecosistemes marins en el punt de vessament i àrea adjacent, prèvia a l’inici de les obres. S’inclouen els resultats i les conclusions del estudis realitzats per diversos grups de recerca, principalment durant Gener-Març 2014, en relació al fons marí, la hidrodinàmica, les praderies de Posidonia oceanica i el mol•lusc bivalve Pinna nobilis, el macro-bentos dels fons circalitorals tous i els contaminants en aigua, sediments i biota, així com en espècies d’interès comercial pel consum humà. Aquest informe es contempla en el contracte entre l’Autoritat Portuària de Balears i el Instituto Español de Oceanografía, subscrit el 5 Febrer 2014, pels treballs d’assistència tècnica per a la revisió i control del Pla de Vigilància Ambiental del dragat de Port de Maó., This document presents the scientific actions developed by the Instituto Español de Oceanografía within the Environmental Monitoring Plan of the works of dredging the Port of Maó (Minorca, Balearic Islands), for the characterization of the marine ecosystems in the point of discharge of dredged material and adjacent area, before the beginning of the dredging. The results and conclusions of the studies developed by several research groups, mainly in January-March 2014, in relation to the bottom, hydrodynamics, Posidonia oceanica meadows, and the bivalve mollusc Pinna nobilis, the macro-benthos of the circalittoral soft bottoms and the contaminants in water, sediments and biota, as well as in commercial species for human consumption, are included. This report is contemplated within the contract between the Autoridad Portuaria de Baleares and the Instituto Español de Oceanografía, signed on 5 February 2014, for the technical assistance activities to review and control the Environmental Monitoring Plan of the works of dredging the Port of Maó., Autoridad Portuaria de Baleares

The inverse estuarine circulation through the strait of Gibraltar is responsible for the overflow of dense, saline MOW towards the Atlantic basin. Initially as a gravity undercurrent, the MOW entrains large amounts of the overlying Eastern North Atlantic CentralWater to become a multi-layered, buoyant plume at depths of 800-1300 m past Cape St. Vincent. Much of the entrainment occurs within 100 km of the Strait over a highly abrupt topography. In this work we analyze a repeated series of high-resolution CTD-LADCP observations along a number of standard sections crossing the early MOW. These data show that from the Strait of Gibraltar, the bottom-trapped flow bifurcates in the vicinity of the topographic features, diverting or rejoining the main MOWpath as a function of the orientation of channels and valleys. As it turns anticyclonically, the undercurrent exhibits a cross-axis geostrophic gradient, with the margin closer to the slope being in near-geostrophic balance whereas the distal band is largely ageostrophic due to the flow curvature. Mixing is steered by the interplay of tidal stirring, bottom roughness, shear instability and double diffusion along the MOWpath. Data also shows that seasonal variability is mostly related to the fluctuations in the overlying layer rather than to MOW dynamics. This is a contribution to INGRES3 project (Mediterranean outflow at Gibraltar, its influence on deep Mediterranean water ventilation and first transformation and coupling with North-Atlantic central waters in the Gulf of Cádiz, CTM2010_21229) Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech