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Forage fish species play a crucial role in most ecosystems, transferring energy from plankton to larger fishes. Therefore, understanding the factors driving the dynamics of forage fish populations is essential in marine ecosystems. Gadiculus argenteus is an important forage fish species in the Galicia and Cantabrian Sea ecosystem. In this study, the influence of several biotic and abiotic factors on the distribution of this species was examined using generalized additive models in a 2-step approach. G. argenteus habitat preference was not affected by changes in annual abundance during the study period (1998-2019). From the variables selected in the final models, depth and geographic location (latitude and longitude) were the most important factors to describe the presence of G. argenteus. Peak abundance was found on the upper slope and although the species was found throughout the study area, its higher abundance values were located in Galician waters. The species seemed to avoid coarse sand bottoms, with mean chlorophyll a concentration showing a positive effect on the presence and abundance of G. argenteus. Interestingly, the observed aggregations of G. argenteus showed a remarkable similarity to the commercial trawling footprint in the area, suggesting a strong link between the distribution of this forage species and the distribution of its predators, most of which are important commercial species. Further work should focus on a better understanding of this relationship to provide important information on the study of the structure and functioning of the marine ecosystem of the northern Spanish continental shelf.

Recent attempts to recover historical data show that, in general, measurements that are not incorporated into standardized databases are irretrievably lost within 10 years. However, some historical records are kept in the institutions, either due to the personal interest of some researchers, or because of good archiving practices maintained over time. The damages of paper records makes their retrieval more and more difficult, and the digitization and validation work is time and effort consuming. Nevertheless, the old data taken time ago are invaluable for climate studies that require the longest time series available in order to establish long-term cycles and trends, as well as to incorporate them into numerical models that allow predict the ocean behavior in relation to climate change. In the 1920s, the Santander Oceanographic Centre, (North coast of Spain), began a series of coastal measures that, with different time lapses, have been maintained over time to the present day. First repeated records of temperature at different depth levels, were made with inversion thermometers and have been kept in log books. A digitization and validation process has recently begun, which will allow the reconstruction of the longest sea temperature series in the area and their climatic characterization. At this time, the monthly measurements carried out from 1928-1964 in the area outside the Bay of Santander have been recovered. After their validation, it is expected that they will be incorporated into the NODC's institutional database for permanent storage and reusing in future studies.

In the framework of global human-induced change, marine communities’ often respond to changing conditions abruptly reorganizing into new equilibria. These shifts are difficult to predict and often imply irreversible adjustments due to hysteresis. Unraveling the role of the forces leading regime shifts is a major challenge. We explored the temporal evolution of 63 fish species representing the Cantabrian bentho-demersal community in response to environmental changes and fishing pressure in the period 1983–2018, using survey data. Via multivariate analysis and non-additive modeling of a community index and the system's main stressors, two decadal-scale regimes were revealed, suggesting a non-linear response of the community to its environment. The Integrated Resilience Assessment framework elucidated the response mechanism to the candidate stressors and allowed quantifying resilience dynamics. The decline in fishing pressure in the 1990s was associated with a gradual transition of the system, while further decline during the 2000s eroded the resilience of the system towards changes in its stressors, leading to a discontinuous response expressed as an abrupt, possibly irreversible shift in the 2010s. Given the teleconnected character of marine ecosystems, this regional study endorses the scientific effort for actions facing the dynamic impacts of climate change on exploited marine ecosystems., Efecto del cambio climático en las comunidades y en las pesquerías del mar Cantábrico, CICLICA, SI

Long time series is a necessity for studying variability and climate change, shelf contained CTD systems were developed in the early 80’s and previously inverted bottles with thermometers, as well as batitermograph and XBT were used and data were hand-recorded. Santander Standard Section, in Southern Bay of Biscay, has been sampled from 1990 covering the shelf, shelf break and deep water, but some information was previously collected in the area. In 1928 Spain was integrated in the ICES and the Spanish Institute of Oceanography (IEO) accepted a mandate for weekly hydrographic sampling and cruises with hydrographic sections in the Western Iberia and Bay of Biscay. Spanish navy boats were used for the sampling and data was sent to the ICES Committees. Knowing that, we have proposed to located those data and all the oceanographic information close to Santander available to enhance the time series. Data from thermometers, batitermograph plates (200 m scale) and XBT (200 and 460m) plots have been quality checked, as much as possible, to be included in the time series. Some Salinity determinations will be presented. The Book of the Santander Laboratory contains 213 temperature profiles of 25, 40 and 100m depth stations from 1928-32, 1950-59 and 1964 and a total of 1585 temperature records. Information increases late due to technical improvement. As a preliminary result, we have detected mix layer temperatures in the older times colder than in the last 30 years. New information will permit describe the last decade 2010-2019 in a wider temporal contest.

The monitoring program Radiales (https://www.seriestemporales-ieo.net/) by the Spanish Institute of Oceanography, has been providing hydrographical and biogeochemical series in marine waters around Spain on a monthly basis from early 90's. The proximity of the shelf-break in front of the city of Santander (SE Bay of Biscay) allowed tracking intermediate and deep waters along the standard section perpendicular to this city for three decades (sampling was limited to 1000 meter until late 2007, then extended to 1500 m, and full-depth 2400 m since 2014). From the start of the sampling in nearly 90`s, subsurface waters showed unabated warming and salt-increase. Warming was linked to isopycnal sinking (heave) during the 90`s and early 00`s until the occurrence of very strong winter mixing in 2005 that shifted quickly the salinity down to lower East North Atlantic Central Waters (ENACW) levels (ca. 400 m). Overall, warming and salt-increase at the core of ENACW added up to 0.3ºC and 0.08 in salinity within only two and a bit decades. In 2014, the upper central waters showed freshening and cooling for the first time in the series, a process that enhanced in the following years especially in salinity that currently (2021) presents the lowest value of the overall timeseries. This shift in regional hydrography follows the large salinity drop observed in the subpolar gyre around 2012 and its subsequent expansion downstream into the subtropical gyre and subarctic seas. This regime shift implies that subsurface environmental conditions in the region have returned back to 90`s state, contrasting to the uppermost waters which continue to show large positive anomalies. The effects of this cold and freshwater inflow in the regional circulation of southern Biscay are discussed.

Biscay-AGL Observatory. Since 1991, shelf and slope waters of the Southern Bay of Biscay are regularly sampled in a monthly hydrographical section north of Santander to a maximum depth of 2500m, as part of the IEO Radiales program. On June 2007, an ocean-meteorological buoy (AGL) was moored at the end of Santander standard section, 22nm north at 2850m depth, to complete the ocean information with the ocean-atmosphere interaction. All of them are part of IEO Observing System (1). The integrated system of AGL and its nearest hydrographic station (2600m depth) is named Biscay-AGL observatory. It is also one station for the EU FixO3 project. Joint resources and systematic analysis lead to a powerful tool, which is much more than the combination of the AGL buoy and the hydrographical samplings. Data Access. All AGL buoy collected data are added to the local database sited at IEO-Santander in real-time and, after rutinary automatised quality controls, they are immediately available through its dedicated webpage (www.boya_agl.st.ieo.es). Monthly CTDO2 data from the hydrographic section are lab-calibrated in order to obtain acurated values of salinity, dissolved oxygen and density, and added to the long-term time series. Biscay-AGL data are quality controlled, flagged and formatted according internationally agreed standards (2, 3) and routinely sent to the IEO Datacenter. This added-value controlled data are incorporated to the IEO permanent archive and made freely available through the SeaDataNet infrastructure for data access and discovery. Derived products. Data acquired by Biscay-AGL may be displayed as timeseries as usual, but end-users are benefited by derived products which provide direct information. A recently developed software tool produces not only timeseries of several parameters at different time resolutions but also derived products, both real and delayed time. Derived products from this buoy include, but not only, annual cycles as well as anomalous values, air-sea heat fluxes, salinity and water temperature anomalies, subinertial currents series, chlorophyll surface series, estimations of the mixed layer depth and wind and currents roses. Sensor Web Enablement (SWE). Sensor Web infrastructures are setup to access real-time data observed by sensors. This system has been implemented in AGL buoy sensors in order to simplify the retrieved events and alerts triggered through sensors. All those functionalities of the Sensor Web are provided in an interoperable way, following the standards stablished by the Open Geospatial Consortium (OGC). By defining standardized service interfaces, these services hides the heterogeneity of the sensor network, its communication details, enabling the access to archived sensor data that can be discovered and accessed using standard protocols and application programming interfaces.

Since 1991, shelf and slope waters of the Southern Bay of Biscay are regularly sampled in a monthly hydrographical section north of Santander. From 2003, a deep hydrological standard section was included and on June 2007, an ocean-meteorological buoy was moored at the end of Santander Section (www.boya_agl.st.ieo.es). All of three are part of IEOOS (IEO Observing System). Biscay AGL is one observatory for the EU FixO3 project. The combination of these resources leads to a powerful tool, Biscay AGL, which is more than the combination of the AGL Buoy and the hydrographical samplings. This tool produces not only time series of several parameters at different time resolutions but also derived products, both real and delayed time. Derived products from this buoy include, annual cycles as well as anomalous values. In particular ones such as air-sea heat fluxes, salinity and water temperatures anomalies, sub inertial currents series, chlorophyll surface series, estimate of the mixed layer depth and wind and currents roses. Many sensor networks have been deployed to monitor marine environment, and more will follow in the future. Due to the large number of sensor manufacturers, integrating diverse sensors into observation systems is not straightforward. By defining standardized service interfaces it is possible to enable access to sensor networks and archived sensor data that can be discovered and accessed using standard protocols and application programming interfaces. Future developments include the deployment of a full sensor network as well as adding new devices to the Biscay AGL tool in order to achieve deeper knowledge of the ocean.

Since 1991, shelf and slope waters of the Southern Bay of Biscay are regularly sampled in a monthly hydrographical section north of Santander, and on June 2007, an ocean meteorological buoy was moored at the end of Santander Section (www. boya_agl.st.ieo.es). Both are part of IEOOS (IEO Observing System). Biscay AGL is one observatory for the EU FixO3 project. Many sensor networks have been deployed to monitor marine environment, and more will follow in the future. Due to the large number of sensor technologies, integrating diverse sensors into observation systems is not straightforward. By defining standardized service interfaces (like those based on OGC standards) it is possible to enable access to sensor networks and archived sensor data that can be discovered and accessed using standard protocols and application programming interfaces, therefore complying with the requirements of the INSPIRE directive. Future developments include the deployment of a full sensor network as well as adding new devices to the Biscay AGL tool in order to achieve a deeper knowledge of the ocean. Biscay AGL is more than the combination of the AGL Buoy and the hydrographical samplings. This observatory produces not only time series of several parameters at different time resolutions but also derived products, both in real and in delayed time. Derived products from this buoy include annual cycles as well as anomalies of physical and biogeochemical magnitudes like air-sea heat fluxes, salinity and water temperatures, sub inertial currents, surface chlorophyll. Different products are derived from in-situ measurements at the AGL buoy like estimates of the mixed layer depth, wind and currents roses and wave intensity diagrams.

Long term time series are an important tool for increasing the knowledge of ocean processes as well as for studying water masses variability in different time scales and changes and tendencies in marine ecosystems. Time series has been classically obtained by oceanographic ships that regularly cover standard sections and stations. From 1991, shelf and slope waters of the Southern Bay of Biscay are regularly sampled in a monthly hydrographic line north of Santander to a depth of 1000 m in early stages and for the whole water column down to 2580 m in recent times. Nearby, in June 2007, the IEO deployed an oceanic-meteorological buoy (AGL Buoy, 43º 50.67’N; 3º 46.20’W, and 40 km offshore, www.boya-agl.st.ieo.es). The long-term hydrographical record have allowed to define the seasonality, trends, and interannual variability at all levels, including the mixing layer and the main water masses North Atlantic Central Water and Mediterranean Water. The relation of these changes with high frequency surface conditions has been examined using the AGL buoy data from 2007 as well as satellite and reanalysis data. On that context and using that combination of sources, some products and quality controlled series of high interest and utility for scientific purposes have been developed and are offered hourly in the web page. Main products obtained are: SST and SSS anomalies, wave significant height character with respect to monthly average, and currents with respect to seasonal averages. Ocean-atmosphere heat fluxes (latent and sensible) are computed from the buoy atmospheric and oceanic measurements. Estimations of the mixed layer depth and bulk series at different water levels are provided in a monthly basis. Quality controlled series are provided for sea surface salinity, oxygen and chlorophyll data. Some sensors are particularly affected by biofouling, and monthly visits to the buoy permit to follow these sensors behaviour. Chlorophyll-fluorescence sensor is the main concern, but Dissolved Oxygen sensor is also problematic. Periods of realistic smooth variations present strong offset that is corrected based on the Winkler analysis of water samples. The incorporation of these observatories on larger scale research programs, as done in 2003 in the framework of the VACLAN and COVACLAN projects, is important in order to provide them with a larger spatial dimension and maximize its utility for process-oriented studies. In 2003, the Santander section was extended 90 miles offshore in the framework of a large-scale hydrographic and circulation monitoring program. Partnerships in a large EU project as FixO3 has provided tools for coordination, homogenization and data validation as well as improve the use of chemical-biological data. 0,0000

There are only a few sites where the deep ocean is ventilated from the surface. The responsible process known as deep convection is recognized to be a key process on the Earth’s climate system, but still it is scarcely observed, and its good representation by global oceanographic and climate models remains unclear. In the Arctic Ocean, the halt of deep convection in the Greenland Sea during the last three decades serves as a natural experiment to study: (1) the conditions that drive the occurrence or not of deep convection and (2) the effects of the halt of deep convection on the thermohaline properties of the deep water masses and circulation both locally and in adjacent ocean basins. Combining oceanic and atmospheric in-situ data together with reanalysis data, we observe that not only on average the winter net heat losses from the ocean to the atmosphere (Qo) have decreased during the last three decades in the Greenland Sea ( Qo (before the 1980s- after the 1980s) = 25 Wm-2) but the intensity and number of strong cooling events (Qo 800Wm-2). This last value for convection reaching 2000 m in the Greenland Sea seems critical to make the mixed layer deepening from being a non-penetrative process to one arrested by baroclinic instabilities. Besides, changes in the wind stress curl and preconditioning for deep convection have occurred, hindering also the occurrence of deep convection. Concerning the effects of the halt of deep convection, hydrographic data reveal that the temperature between 2000 meters depth and the sea floor has risen by 0.3 C in the last 30 years, which is ten times higher than the temperature increase in the global ocean on average, and salinity rose by 0.02 because import of relatively warm and salty Arctic Ocean deep waters continued. The necessary transports to explain the observed changes suggest an increase of Arctic Ocean deep water transport that would have compensated the decrease in deep water formation rate after the 1980s. The effects of these changes in adjacent basins remain unstudied, but the bottom waters seem to be upwelled towards the slope and the Jan Mayen ridge, being an exit for the Greenland Sea deep waters. 0,0000

The Workshop on Long‐term Variability in Southwestern Europe (WKLTVSWE) was held in Lisbon, Portugal from 13 to 16 February 2007, a joint effort of ICES and GLOBEC and endorsed by EUR‐OCEANS (http://www.eur‐oceans.org). In 1997, GLOBEC’s SPACC (Small Pelagic Fish and Climate Change) initiative held a joint meeting with SCOR Working Group 98 on worldwide, large‐scale fluctuations in sardine (Sardinops sagax) and anchovy (Engraulis spp.) populations (Schwartzlose et al., 1999). It was decided then to continue this “global” undertaking with a series of regional workshops. Previous meetings had focused on the Benguela Current in 2001 (Cury and Shannon, 2004), the Humboldt Current in 2002 (Alheit and Niquen, 2004), and Japanese waters in 2003. During the 2005 annual meeting of the former ICES Study Group on Regional Ecology of Small Pelagics (SGRESP) – subsequently ICES/GLOBEC Working Group on Life Cycle and Ecology of Small Pelagic Fish (WGLESP) – it was recommended that this series of workshops be continued with a meeting focusing on the waters surrounding the Iberian Peninsula, including the western Mediterranean Sea., 0

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Esta obra ofrece una síntesis de la información recogida en las series temporales de observaciones oceánicas del IEO en la región atlántica del norte de España iniciadas en 1943 con el registro mareográfico; muestra evidencias de cambios interanuales en la física, la química y la biología del océano en relación con los factores climáticos, y estima los impactos más probables del clima en el océano futuro. Este volumen continúa la serie de estudios de la influencia del cambio climático en el mar iniciada con el Cambio climático en el Mediterráneo español (Vargas Yánez et al., 2010). En este caso, el enfoque es multidisciplinar, empleando, por primera vez, series de observaciones recogidas de forma coordinada y simultánea. A lo largo de sus ochos capítulos, se analiza la variabilidad climática atmosférica reciente y su influencia sobre las condiciones oceanográficas de la región, especialmente en relación con la intensidad y frecuencia del afloramiento de aguas profundas que determina, en gran medida, el aporte estacional de nutrientes a la superficie y, por tanto, la producción biológica. Se describen las tendencias en el nivel del mar a partir de las medidas de los mareógrafos de la zona con una estimación de los niveles extremos esperados a largo plazo. Se realiza un análisis comparativo –entre Galicia y el Cantábrico– de la variabilidad en los nutrientes inorgánicos y se determinan los elementos limitantes de la producción primaria en cada zona. Finalmente, se analizan las variaciones en las comunidades de fitoplancton, picoplancton y zooplancton como indicadoras de cambios en el ecosistema pelágico, destacando las fluctuaciones en la biomasa y producción primaria, base de la red trófica pelágica de la región, y la presencia de medusas y salpas y su relación con el clima. This book presents a synthesis of the oceanic time-series observations of IEO in the Atlantic region of northern Spain. These series, starting in 1943 with tide-gauges, reveal evidence of interanual changes in physical, chemical and biological properties of the ocean that were related to climatic factors, allowing to estimate future impacts of climate on the ocean. The volume continues the series started with “Climate Change in the Spanish Mediterranean” (Vargas Yánez et al., 2010). In this case the study is multidisciplinary, including for the first time series obtained in coordinated and simultaneous observational programs. The eight chapters first analyse recent climatic variability and its influence on the regional oceanography, particularly in relation to the intensity and frequency of the deep-water upwelling that largely determines the seasonal inputs of nutrients and primary production in this region. Next, the main trends in sea level revealed by tidal gauges along with the estimates of expected extreme levels are described. The variability in inorganic nutrients and the identification of limiting elements for primary production were presented as a comparative analysis between Galicia (in the West) and the Mar Cantábrico (in the east). Finally, the variability in the composition of the plankton communities, including phytoplankton, picoplankton and zooplankton, is analysed as indicative of changes in the pelagic ecosystem. Particular attention is given to the fluctuations in primary biomass and production and to the presence of salps and jellyfish in relation to climate. Versión del editor

Esta obra ofrece una síntesis de la información recogida en las series temporales de observaciones oceánicas del IEO en la región atlántica del norte de España iniciadas en 1943 con el registro mareográfico; muestra evidencias de cambios interanuales en la física, la química y la biología del océano en relación con los factores climáticos, y estima los impactos más probables del clima en el océano futuro. Este volumen continúa la serie de estudios de la influencia del cambio climático en el mar iniciada con el Cambio climático en el Mediterráneo español (Vargas Yánez et al., 2010). En este caso, el enfoque es multidisciplinar, empleando, por primera vez, series de observaciones recogidas de forma coordinada y simultánea. A lo largo de sus ochos capítulos, se analiza la variabilidad climática atmosférica reciente y su influencia sobre las condiciones oceanográficas de la región, especialmente en relación con la intensidad y frecuencia del afloramiento de aguas profundas que determina, en gran medida, el aporte estacional de nutrientes a la superficie y, por tanto, la producción biológica. Se describen las tendencias en el nivel del mar a partir de las medidas de los mareógrafos de la zona con una estimación de los niveles extremos esperados a largo plazo. Se realiza un análisis comparativo –entre Galicia y el Cantábrico– de la variabilidad en los nutrientes inorgánicos y se determinan los elementos limitantes de la producción primaria en cada zona. Finalmente, se analizan las variaciones en las comunidades de fitoplancton, picoplancton y zooplancton como indicadoras de cambios en el ecosistema pelágico, destacando las fluctuaciones en la biomasa y producción primaria, base de la red trófica pelágica de la región, y la presencia de medusas y salpas y su relación con el clima., This book presents a synthesis of the oceanic time-series observations of IEO in the Atlantic region of northern Spain. These series, starting in 1943 with tide-gauges, reveal evidence of interanual changes in physical, chemical and biological properties of the ocean that were related to climatic factors, allowing to estimate future impacts of climate on the ocean. The volume continues the series started with “Climate Change in the Spanish Mediterranean” (Vargas Yánez et al., 2010). In this case the study is multidisciplinary, including for the first time series obtained in coordinated and simultaneous observational programs. The eight chapters first analyse recent climatic variability and its influence on the regional oceanography, particularly in relation to the intensity and frequency of the deep-water upwelling that largely determines the seasonal inputs of nutrients and primary production in this region. Next, the main trends in sea level revealed by tidal gauges along with the estimates of expected extreme levels are described. The variability in inorganic nutrients and the identification of limiting elements for primary production were presented as a comparative analysis between Galicia (in the West) and the Mar Cantábrico (in the east). Finally, the variability in the composition of the plankton communities, including phytoplankton, picoplankton and zooplankton, is analysed as indicative of changes in the pelagic ecosystem. Particular attention is given to the fluctuations in primary biomass and production and to the presence of salps and jellyfish in relation to climate.

In the late 80's, the Spanish Institute of Oceanography (IEO) began some ambitious programs of monitoring around the Iberian Peninsula. The coastal observing system core structure was the Radiales program, a series of transects nearby most coastal IEO laboratories where a minimum set of hydrographical, chemical and biological parameters is sampled monthly. The sections are designed to be completed in one-day journeys so the system is supported by quite small vessels, mainly covering the continental shelf with the noteworthy exception of the Santander Section, where the proximity of the shelf-break allows sampling deep waters monthly. During the last 20 years the program has supported many specific scientific research projects and has created a detailed description of seasonal to interannual variability in the coastal ecosystem that serves as a baseline to explore long-term changes or trends...

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