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Report on the environmental monitoring (geophysics, seabed sampling, physical and chemical characteristics, and planton) made on the submarine volcano of Tagoro (El Hierro Islands) to evaluate the degree of affection and recovery on the marine ecosystem of the last volcanic eruption in the Canary region, making it extendable to other regions of the Canary Islands of possible hydrothermal or volcanological interest. In this sense, the "Enmedio" volcano has been investigated, between the islands of Gran Canaria and Tenerife., Instituto Español de Oceanografía

El objetivo principal del proyecto “Physico-chemical, biological and geological study of an underwater volcano in a degassing stage: Island of El Hierro”, (VULCANO-II) es estudiar, desde un punto de vista totalmente interdisciplinar, la fase de desgasificación activa del único volcán submarino monitoreado desde su nacimiento en aguas españolas. De esta forma, se pretende además, dar continuidad a los estudios multidisciplinares realizados sobre el volcán submarino de la isla de El Hierro en el contexto del proyecto del Plan Nacional VULCANO-I, (CTM2012-36317) y VULCANA (Vulcanología Canaria Submarina, IEO). Para ello, se realizará la monitorización de las propiedades físico-químicas, biológicas y geológicas del proceso eruptivo submarino de la isla de El Hierro y otros puntos sensibles, como el volcán de Enmedio entre Gran Canaria y Tenerife

El objetivo principal del proyecto Vulcana (Vulcanología Canaria Submarina), es evaluar el grado de afección y la recuperación sobre el ecosistema marino del volcán submarino Tagoro de la isla de El Hierro, haciéndolo extensible a otras regiones de posible interés hidrotermal o vulcanológico. Para ello, se realizará un estudio completo de las propiedades físico-químicas, biológicas y geológicas en las áreas descritas. Versión del editor

Comunicación presentada al V Simposio Internacional de ciencias del Mar celebrado en alicante entre el 20 y el 22 de julio de 2016. Between October 2011 and March 2012 a submarine volcanic eruption took place at the offshore of El Hierro Island. The extensive study of the eruption and subsequent degassing process has allowed monitoring the newly generated volcanic edifice. Multibeam bathymetric has enabled building a digital high-resolution bathymetric model (grid 1x1 m). The preliminary analysis of the geomorphology of this volcanic eruption displays four main features: i) the edifice consists of a principal and a series of secondary cones distributed in NW-SE trend; ii) two escarpments NE-SW directed that partially match with inherited flanks of the previously existing valley; iii) three crests, one of them interpreted as the prolongation of a NE-SW scarp and the other as the head of gravitational instabilities of NE-SW and N-S direction at the main hill; and iv) mixed lava and dense pyroclastic flows extended from the volcanic edifice to the southwest and characterized by a high slope front, that probably represents the maximum distance reached by the main lava products. Versión del editor

El objetivo principal del proyecto VULcanología CAnaria submariNA, VULCANA, es evaluar el grado de afección y la recuperación sobre el ecosistema marino del volcán submarino de la isla de El Hierro, haciéndolo extensible a otras regiones canarias de posible interés hidrotermal o vulcanológico. En este sentido, se ha investigado además el volcán de “enmedio”, entre las islas de Gran Canaria y Tenerife y el sur de La Palma (Fuentesanta). Para ello, se realizará un estudio completo de las propiedades físico-químicas, biológicas y geológicas en las áreas descritas

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

Due to the high density and heat capacity of water, the ocean modulates climate in scales much larger than the atmosphere, both spatially and temporally. In order to understand the mechanisms governing this internal variability of the ocean, and therefore climate, it is necessary to have long systematic observations. The Atlantic Meridional Overturning Circulation (AMOC), which is composed by the south- north circulation, transports 18Sv (1Sv=10E6m3/s) of water that carries more that 1.5PW (1PW=10E15W) of heat to the North Atlantic, and therefore plays a determining role in regulating the climate in Europe. An important component of the AMOC is the subtropical gyre, the largest oceanic structure of the North Atlantic. The Canary Islands are immersed in the eastern margin of the subtropical gyre, in the coastal transition zone of the Canary Current Upwelling System and therefore they are an ideal place for the study of the subtropical gyre variability. With this background, in 2006 the Spanish Institute of Oceanography began (IEO) the program deep hydrographic section around the Canary Islands (Raprocan), in order to establish the scales of variability in the range decadal/subdecadal in the subtropical gyre, specifically in its eastern margin. Based on previous results the observational strategy of Raprocan consists in hydrographic cruises in two seasons, with 50 hydrographic stations around the Canary archipelago. In each one of the stations velocity, temperature, salinity, pressure, oxygen, turbidity and fluorescence is continuously measured ( CTD ). In each station 24 samples are taken for calibration of the above variables as well as for determination of alkalinity, carbon content and chlorophyll. This program is carried out in collaboration with the University of Las Palmas de Gran Canaria (ULPGC) and with the Oceanic Platform of the Canary Islands (PLOCAN) that provides glider data since 2013. The warming of the upper 600 m continues at a rate of 0.14 ° C/ decade in the oceanic waters and 0.32 ° C / decade in the waters between Lanzarote and Africa under influence of upwelling off the African coast. At intermitted levels the warming continues at rate of 0.04 ° C/ decade in the oceanic waters and 0.08 ° C / in the waters between Lanzarote and Africa. At deeper levels, since 1997 there is not statistical significant trend. Regarding the oceanic circulation, the Canary Current presents a seasonal cycle, with the minimum transport occurring during fall, when only carries 3 Sv. During this season the transport is concentrated between the islands of Tenerife and Lanzarote and in the first 400 meters.

In October 2011, the shallow submarine eruption of the southern part of El Hierro (Canary Islands) caused severe effects in the seafloor morphology and substrate composition (e.g. lava extrussion and construction of the volcanic edifice), the water column (e.g. acidification, deoxygenation and fertilization) and the biological communities (e.g. changes in the composition and functioning of communities) (Fraile-Nuez et al. 2012; Santana-Casiano et al. 2013). Due to this natural event, habitats and associated biota have experimented changes at different levels and in different parts of this new seafloor volcanic structure. Underwater images obtained with VOR Aphia 2012 (October 2013) and ROV Liropus 2000 (March 2014) as well as samples collected with a benthic dredge in March and October 2013 have made possible the study of the benthic and demersal organisms that persisted after this acute natural event as well as those that are recolonizing the recently formed volcanic bottoms. During the eruption, material of variable size and texture buried previous existing habitats and associated biota, except in certain bathyal bottoms close to the base of this new seafloor structure (200 - 500 m depth) where slow-growing suspension-feeders such as antipatharians (e.g. Stichopathes cf. gracilis, Antipathes furcata), small gorgonians (e.g. Acanthogorgia, Bebryce) and lithistid sponges still increase the bottom complexity when compared to those buried bottoms. Among them, small colonies of cold-water corals (probably Dendrophyllia cornigera and Cladocora debilis) also occur, but mostly represented by dead specimens. In both March and October 2013, benthic dredge samples collected lava rocks and gravels that were poorly colonized by invertebrates, together with remains of antipatharians and dead cold-water corals. In shallower parts of the flanks of the volcano (ca. 200m depth), most previously existing habitats formed by antipatharians have been buried after the eruptive processes and the recent lava rocks are starting to be colonized by small and scarce colonies of hydrozoans, serpulids and small size echinoids (e.g. Coelopleurus floridianus), among other species. Nevertheless, the gravel bottoms at this bathimetric level display a higher degree of colonization, with higher abundances of polychaetes (e.g. Glyceridae, Polynoidae), decapods (e.g. Alpheus spp., Heterocrypta maltzami) and some molluscs (e.g. Nassaridae), probably linked to previous succesful recruitment events or horizontal movements from adjacent unimpacted bottoms. The fish Anthias anthias and the decapod P. narval are two of the top dominant demersal organisms that have recolonized this area after the eruption. Close to the summit, one of the top-dominant sessile macroinvertebrates is the oyster Neopycnodonte cochlear, which occurs at densities of more than 100 indiv. m􀀀�2 in some of the large lava rocks and represent one of the first sessile colonizers of the lava erupted by the vulcano. This filter feeder is also very abundant on black-corals and undisturbed hard substrates located nearby at similar depths and may have benefited from the new micro-habitats available in the hard bottoms formed and the fertilization process after the eruptive event. In general, a pattern of decreasing species richness of benthic-demersal organisms has been found from close to the summit to the base of the volcano, where the low colonization rate is a result of the lower number of potential species that are able to recolonize these substrates, the specific biological features of these species (e.g. slow growth rates, small reproductive outputs) and the oligotrophic character of the water masses when compared to the summit. The findings highlight that the volcanic eruption firstly buried most previously existing habitats and later on created a highly unstable and corrosive environment that affected some slow-growing organisms (e.g. cold-water corals) but not others (e.g. antipatharians). Nevertheless, the eruption provided nutrients that are important for primary pelagic production that may have also promoted the establishment of dense populations of some sessile suspension feeders (e.g. N. cochlear, hydrozoans) in the newly formed hard substrates. This study has been funded by the project VULCANO (CTM2012-36317) and MONTERA (CTM2009- 14157-C02) and we deeply appreciate the help of the Captains and all the crews of R/V A´ ngeles Alvarin˜o and R/V Ram´on Margalef as well as other colleagues during the sampling expeditions. FEDER funding assigned to construction of R/V Ramo´n Margalef (FICTS-2011-03-01) and R/V A´ ngeles Alvarin˜o (FICTS-2011-03-02) is also acknowledged.

Memoria del Informe Cintífico-Técnico de la campaña oceanográfica SUBVENT-1.Anexos de operatividad y de las distintas técnicas utilizados a lo largo de la misma. La campaña SUBVENT1-0913 se ha realizado a lo largo del talud inferior del margen continental de las Islas Canarias, área que también es conocida en la literatura como Cuenca Canaria. Esta zona se caracteriza por la presencia de una serie de estructuras geológicas recientes, así se encuentran la parte distal de los depósitos de debris procedentes de las avalanchas volcánicas generadas desde las Islas Canarias, a favor de la pendiente y probablemente en relación con episodios eruptivos. En la parte meridional se encuentra además un conjunto de montes submarinos, de diversa entidad, de origen volcánico y, en general, aparece todo un conjunto de montículos con desniveles comprendidos entre 30 y 300 m que han constituido el principal objetivo de esta campaña. Así mismo, en este sector existen numerosos escarpes lineales de orientación subparalela a la del propio talud a los que se encuentran asociados en ocasiones los citados montículos. La adquisición de nuevos datos geofísicos y el muestreo llevado a cabo durante la campaña permitirá conocer mejor el origen de estos montículos y el proceso de emisión que los ha generado. Por otro lado, el conocimiento de las relaciones entre los sedimentos de debris y hemipelágicos junto con los asociados a las posibles emisiones de la zona permitirá conocer no sólo la evolución sedimentaria de este margen, sino establecer los episodios de emisión que generaron los montículos y conocer sus patrones de crecimiento. Así mismo, se podrá evaluar la tasa de sedimentación de la zona y el papel de la masa de agua de fondo antártica (AABW) en esta evolución. The SUBVENT1-0913 cruise has been carried out along the lower slope of the continental margin of the Canary Islands. This area is characterized by the presence of several recent geological structures. Among these are the distal parts of the volcano-clastics debris deposits originated by volcanic avalanches of the Canary Islands, transported by gravity along the slope and probably related in origin to eruptive episodes. In the southern part, numerous and different reliefs (seamounts, hills or mounds) of volcanic origin occur. The most frequents features display heights between 30 and 300 m and they have constituted one of the main aims of this survey. Moreover, in this sector there are several subparallel linear scarps with similar directions to the slope trend that could be associated with the aforementioned mounds. The acquisition of new geophysical data and samples during this campaign will allow a better understanding of the origin of these mounds and the emission processes that have generated them. On the other hand, the knowledge of the relationships between debris and hemipelagic sediments together with those associated with possible venting processes in the area, will reveal not only the sedimentary evolution of this margin, but also to establish emission episodes generating mounds and to know their growth patterns. Furthermore, it would be possible to evaluate the sedimentation rate in the area and the role played by the Antarctic Bottom Water (AABW) mass on this process. Plan Nacional de I+D, Ministerio de Economía y Competitividad. Investigación fundamental no Orientada. Proyecto de Investigación Coordinado SUBVENT “Emisiones submarinas de fluidos en los márgenes continentales de las Islas Canarias y del Golfo de Cádiz: Análisis comparativo de las construcciones asociadas” (CGL2012‐39524‐C02). Acción Complementaria EXARCAN “Trabajos científico-técnicos para la preparación, presentación y defensa de las propuestas de España ante Naciones Unidas para la Extensión de la Plataforma Continental de las Islas Canarias y Galicia” (CTM2010-09496-E).

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