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Research in marine Spanish waters are focused on several actions to achieve an effectively management on protected areas, with the active participation of the stakeholders and research as basic tools for decision-making. Among these actions, there is one about the knowledge and control on NIS. One of its objectives is the creation of NIS factsheets, which are going to be added to the National Marine Biodiversity Geographical System (GIS) providing complementary information about taxonomic classification, common names, taxonomic synonyms, species illustrations, identification morphological characters, habitat in the native and introduced regions, biological and ecological traits, GenBank DNA sequences, world distribution, first record and evolution in the introduced areas, likely pathways of introduction, effects in the habitats and interaction with native species, and potential management measures to apply. The database will also provide data for (1) the European online platforms, (2) the environmental assessment for the Descriptor 2 (D2-NIS) of the EU Marine Strategy Framework Directive (MSFD), as well as (3) supporting decisions made by stakeholders. It is the result of extensive collaboration among scientist, manager’s and citizen science in the Spanish North-Atlantic, South-Atlantic, Gibraltar Strait-Alboran, Levantine-Balearic and Canary Islands marine divisions, providing an updated overview of the spatial distribution of relevant extended and invasive NIS of recent and established NIS introduced by maritime transport and aquaculture pathways, as well as on cryptogenic or native species in expansion due to the climatic water warming trend.

Los fondos marinos profundos del margen Ibérico albergan zonas que han sido poco exploradas hasta la fecha y que contienen montañas, cañones submarinos y volcanes de fango entre otros relieves marinos, así como diferentes hábitats, algunos conformados por singulares comunidades quimiosintéticas y otros por complejos corales centenarios que ofrecen refugio y alimento a diferentes especies. En los últimos años, el avance de nuevas tecnologías de estudio del fondo marino ha permitido localizar y cartografiar estas zonas, y por otro lado aumentar el conocimiento de su biodiversidad. Algunas de las especies ya eran conocidas para otras zonas similares del Mediterráneo o Atlántico, pero otras han resultado ser citas nuevas para las aguas españolas e incluso nuevas especies para la ciencia. En este trabajo mostramos algunas especies recientemente encontradas en aguas del golfo de Cádiz y del mar de Alborán. Se trata de especies del filo Bryozoa, las cuales han sido poco estudiados entre el norte de África y el sur de Europa, donde se encuentra una alta biodiversidad de especies provenientes del Atlántico boreal, Mediterráneo y zona subtropical africana. 0

Chella Bank (also known as Seco de los Olivos seamount) is a volcanic submarine elevation (76–700 m deep) located ca. 16 km off the southern coast of Spain, within the Alboran Sea, in the Atlantic-Mediterranean transition zone. It represents a biodiversity hotspot for Europe, with more than 600 species listed to date, and contains several habitats included in the EU Habitats Directive. During three ship-based expeditions, several areas of Chella Bank were surveyed and sampled in a depth range of 95–729 m, resulting in new records that improve our knowledge on poorly studied phyla, such as bryozoans. In 14 of the 21 samples examined during this study, 43 bryozoan taxa could be identified. Among these, one species is described as new to science (Buskea medwaves sp. nov.) and three other ones are reported for the first time from the Mediterranean Sea, namely Terminoflustra barleei (Busk, 1860), Marguetta pulchra Jullien in Jullien & Calvet, 1903, and Schizomavella (Schizomavella) linearis profunda Harmelin & d’Hondt, 1992a. Some species were abundant in the samples, such as Adeonellopsis distoma (Busk, 1859), B. medwaves sp. nov., Entalophoroecia cf. deflexa, and Reteporella pelecanus López de la Cuadra & García-Gómez, 2001. The highest species richness was detected in rhodolith beds and on coral rubble bottoms (especially exposed above the sediments) compared with other bottom types and habitats such as sandy bottoms and muddy bottoms. The finding highlights the importance of these environments for bryozoans., MONCARAL, MONtículos CARbonatados Mar de Alborán, DEMALBORAN, Evaluación de Recursos Demersales por métodos directos en el Mar de Alborán, SI

The Iberian margin in the Gulf of Cádiz hosts a fluid venting area embedded into a contourite depositional drift and is a natural laboratory to study how multiple interacting processes shape the seafloor. A high-resolution morpho-sedimentary analysis, based on geophysical data, sediment samples and submarine imagery, has been carried out; the onset and evolution of the main geoforms are discussed; and the influence of geological, oceanographic and biogenic processes conditioning substrate types and benthic community distribution are evaluated. The interplay of geological (e.g., salt and shale diapirism, mud volcanism), oceanographic (e.g., water mass circulation, secondary circulation, vertical eddies, internal waves) and biogenic (e.g., methane derived authigenic carbonates formation, coral mound aggradations) processes drive the formation of a large variety of geoforms including, among others, contourite drifts, channels, diapiric ridges, mud volcanoes, pockmarks, and coral mounds. At a smaller scale, the interaction between massive and fluid extrusive, biogenic, and bottom current-related processes (both depositional and erosive) determines the distribution of substrate types and benthic communities, which have been classified as belonging to different biotopes.

Cold-water corals are recognised as a key component of Mediterranean deep-sea ecosystems but the knowledge of their associated biodiversity is still limited. To date, the fauna associated to the Central Mediterranean cold-water coral habitats is the best known (e.g. the cold-water coral provinces of Santa Maria di Leuca, Bari canyon and Strait of Sicily) but such knowledge should be extended to the whole Mediterranean Basin. The combined biodiversity censed so far for Mediterranean cold-water coral habitats and those of adjacent areas (Strait of Gibraltar-Gulf of Cádiz) includes a conspicuous number of species (ca. 520 spp.) with a high representation of sponges (ca. 90 spp.), polychaetes (ca. 90 spp.), cnidarians (ca. 80 spp.), bryozoans (ca. 75 spp.), crustaceans (ca. 60 spp.), molluscs (ca. 50 spp.), fishes (ca. 50 spp.), echinoderms (ca. 20 spp.) and brachiopods (7 spp.). Most species are not univocally linked to cold-water corals, but they benefit from the complex and diverse microhabitats provided by them. There is a clear need to continue the investigation of Mediterranean cold-water coral habitats to fully document the faunistic inventory, biogeographic connections and functions of the many species connected to such emblematic ecoystems of the deep-sea.

Cold-water corals are recognised as a key component of Mediterranean deep-sea ecosystems but the knowledge of their associated biodiversity is still limited. To date, the fauna associated to the Central Mediterranean cold-water coral habitats is the best known (e.g. the cold-water coral provinces of Santa Maria di Leuca, Bari canyon and Strait of Sicily) but such knowledge should be extended to the whole Mediterranean Basin. The combined biodiversity censed so far for Mediterranean cold-water coral habitats and those of adjacent areas (Strait of Gibraltar-Gulf of Cádiz) includes a conspicuous number of species (ca. 520 spp.) with a high representation of sponges (ca. 90 spp.), polychaetes (ca. 90 spp.), cnidarians (ca. 80 spp.), bryozoans (ca. 75 spp.), crustaceans (ca. 60 spp.), molluscs (ca. 50 spp.), fishes (ca. 50 spp.), echinoderms (ca. 20 spp.) and brachiopods (7 spp.). Most species are not univocally linked to cold-water corals, but they benefit from the complex and diverse microhabitats provided by them. There is a clear need to continue the investigation of Mediterranean cold-water coral habitats to fully document the faunistic inventory, biogeographic connections and functions of the many species connected to such emblematic ecoystems of the deep-sea.

Tagoro, the youngest submarine volcano of the Canary Islands, erupted in 2011 South of El Hierro Island. Pre-existing sea floor and inhabiting biological communities were buried by the newly erupted material, promoting the appearance of new habitats. The present study pursues to describe the first metazoans colonizing different new habitats formed during the eruption and to create precedent on this field. Through dredge and remote operated vehicle samplings, five main habitat types have been detected based on the substrate type and burial status after the eruption. Inside the Tagoro volcanic complex (TVC), two new habitats are located in and around the summit and main craters—hydrothermal vents with bacterial mats and sulfurous-like fields mainly colonized by small hydrozoan colonies. Two other habitats are located downslope the TVC; new hard substrate and new mixed substrate, holding the highest biodiversity of the TVC, especially at the mixed bottoms with annelids (Chloeia cf. venusta), arthropods (Monodaeus couchii and Alpheus sp.), cnidarians (Sertularella cf. tenella), and molluscs (Neopycnodonte cochlear) as the first colonizers. An impact evaluation was done comparing the communities of those habitats with the complex and well-established community described at the stable hard substrate outside the TVC, which is constituted of highly abundant hydrozoans (Aglaophenia sp.), antipatharians (Stichopates setacea and Antipathes furcata), and colonizing epibionts (e.g., Neopycnodonte cochlear). Three years after the eruption, species numbers at Tagoro were still low compared to those occurring at similar depths outside the TVC. The first dominant species at the TVC included a large proportion of common suspension feeders of the circalittoral and bathyal hard bottoms of the area, which could have exploited the uncolonized hard bottoms and the post eruptive fertilization of water masses.

An exceptional species richness for Mollusca was found on Avempace bank (349-365 m), Djibouti group, Alboran Sea, where the most abundant species was the crinoid Leptometra phalangium. A sample of sediment sieved on a 0.5-mm mesh yielded 156 species of molluscs (83 live-taken, 1772 specimens) with a high Shannon-Wiener diversity index (H’(log2)=3.60). The dominant mollusc was Limopsis aurita and the six most common species accounted for 77% of the specimens. On the other hand, 42 species were represented by only one or two specimens. Two species are described as new, three more are first findings in the Mediterranean and two are first findings in Iberian waters. One-third of the species have not been reported from the neighbouring, well-explored Alboran Island platform. There is a considerable balance between the trophic groups, denoting a stable and structured community. Most of the species have an extensive Atlantic range, and most have a planktonic larval stage. Therefore, it can be hypothesized that the fauna benefits from a diverse influx of larvae carried in by the more superficial incoming Atlantic current. Because of its exceptional richness, this type of bathyal community with Leptometra and Limopsis should be considered a high priority for habitat conservation in the Mediterranean deep sea. Se encontró una excepcional riqueza específica de moluscos en el banco Avempace (349-365 m), grupo de Djibouti, mar de Alborán, donde la especie más abundante fue el crinoideo Leptometra phalangium. En una muestra de sedimento tamizada sobre una malla de 0.5 mm se hallaron 156 especies de moluscos (83 con ejemplares vivos) y 1772 ejemplares, con un alto valor del índice de diversidad Shannon-Wiener (H’(log2)=3.60). El molusco dominante era Limopsis aurita y las seis especies más comunes eran el 77% de los ejemplares. Por otro lado, 42 especies estuvieron representadas únicamente por uno o dos ejemplares. Dos especies se describen como nuevas; tres más son primera cita para el Mediterráneo y dos son primera cita en aguas ibéricas. Un tercio de las especies no están citadas en la plataforma de la vecina isla de Alborán, por su parte bastante estudiada. La representación de los distintos grupos tróficos es equilibrada, denotando una comunidad estable y estructurada. La mayoría de las especies tienen una amplia distribución en el Atlántico y una fase larvaria planctónica. Por lo tanto se supone que la fauna se beneficia de un aporte diverso de larvas por la corriente superficial que entra desde el Atlántico. Por su excepcional riqueza, este tipo de comunidad batial con Leptometra y Limopsis merece considerarse prioritaria para la conservación de hábitats profundos del mar Mediterráneo.

This study describes the composition and structure of discards of the stripped venus clam (Chamelea gallina) fishery, and the damage caused by mechanized dredges on discarded species in the Alboran Sea. A total of 106 commercial fishing hauls have been analyzed between March 2013 and March 2014. Samples were collected on board artisanal fishing vessels based in Fuengirola and Caleta de Vélez harbours (Málaga). The collected fauna was characterized considering the damage presented by using a three level scale: no damage, intermediate damage and severe damage. Quantitative and qualitative data were analyzed with multivariate methods for contrasting seasonal variability. A total of 98 species were identified, with molluscs being the best-represented taxa (e.g. Acanthocardia tuberculata, Mactra stultorum), followed by decapod crustaceans (e.g. Portumnus latipes, Liocarcinus vernalis) and echinoderms (e.g. Echinocardium cf. mediterraneum, Ophiura ophiura). Most individuals displayed no damage after their capture. Echinoderms displayed the highest proportion of damaged individuals, followed by mollucs and decapod crustaceans. The discard structure and damage on non-target species displayed significant seasonal differences, with the higher proportions of damaged individuals in winter.

The Gulf of Cadiz is located in the boundary of two lithospheric plates, this tectonic activity promote fluid rich hydrocarbon emissions from subsurface reservoirs and the formation of several mud volcanoes. The seabed and sedimentological heterogeneity, the complex oceanographic circulation, and the low fishing activity in certain areas may promote high biodiversity and complex habitats (habitat 1170 and 1180, Natura 2000). Environmental variables (fishing activity, substrate types, near bottom currents) and fauna collected with beam-trawl have been compared for several mud volcanoes and adjacent bottoms in order to understand the spatial distribution of both habitats and environmental/anthropogenic variables. The faunistic samples yielded high abundances, biomass and species richness in Gazul, Pipoca and Chica but low ones in Anastasya. In relation to environmental variables and fisheries activity, there is a strong correlation with the substrate type, depth, salinity and near-bottom current as primary variables influencing the distribution of habitats of different mud volcanoes. In this context, high species richness, abundance and biomass was found in areas with authigenic carbonates, coarse sediments, high near-bottom current speed, low salinities and low fishing activity.

Molluscan assemblages from shelf and slope soft bottoms of the Alboran Sea have been sampled with a beam trawl during 2014 and 2015 MEDITS expeditions. A total of 134 spp. of molluscs (shell size > 3 mm) were identified, being gastropods the most diverse and dominant group. Four main depth related assemblages were detected in multivariate analyses and characterized by (1) Turritella communis, Chamelea striatula and Nucula sulcata for the inner shelf, (2) Timoclea ovata, Clelandella miliaris and Neopycnodonte cochlear for the outer shelf, (3) Nassarius ovoideus, Calumbonella suturale and N. sulcata for the upper slope and (4) Abra longicallus, Euspira fusca and Aporrhais serresianus for the middle slope. Species richness and abundance decreased with depth, unlike evenness and Shannon-Wiener diversity which displayed an opposite pattern. A higher spatial variability was detected for the shelf, indicating that more assemblages may occur at this level and further sampling is needed for covering all sedimentary habitat types of the Alboran Sea.

The present study describes the composition, structure and damage caused by mechanized dredges on discarded species from the wedge clam (Donax trunculus Linnaeus 1758) fisheries in the Alboran Sea. Discard samples were collected on board artisanal fishing vessels in 95 commercial hauls performed in Fuengirola and Caleta de Vélez between March 2013 and March 2014. The collected fauna was characterized according to their abundance and biomass, and considering their damage type by using a three-level scale (no damage, intermediate damage and severe damage) defined for the different faunal groups identified. Data was analysed for contrasting variations in the different areas and seasons. A total of 87 species were identified, including Paguridae and Annelida. Molluscs were the best represented faunal group, followed by decapod crustaceans and echinoderms. Other groups did not usually exceed 1% of the total abundance and biomass such as fishes or sipunculids. Most discarded individuals displayed no damage after their capture, promoting therefore a high survival rate. Among the dominant taxa, echinoderms and crustaceans displayed the highest proportion of damaged individuals due to their fragile exoesqueletons, which make them to be highly vulnerable to the physical impact caused by mechanized dredges and the further processing on board.

The Gulf of Cádiz (GoC) represents an important area of seepage activity and of biological diversity due to the tectonic activity and subsoil fluid mobility, as well as the confluence of Atlantic and Mediterranean water masses and organisms from both basins. Some circalittoral and bathyal areas of the GoC remain still unexplored and they could harbour interesting communities and species that may deserve protection. In summer 2013, a geological expedition carried out between San Fernando and Conil de la Frontera, at water depths between 40 and 55 m and 10 M from Cádiz detected complex coralligenous communities that may be linked to diapiric processes. These communities represent a well preserved 1170 habitat type (Reefs) of the Habitat Directive and also contain ca. 20 spp. of invertebrates that are included in European, National and Local (Andalusian) threatened species lists. The area should be included in the Natura 2000 network as it represents one of the few circalittoral coralligenous communities from Spanish waters of the GoC.

Beam-trawl samples were collected during the MEDITS survey in 2014. These samples covered the continental shelf and slope bottoms of the north Alboran Sea, including the Alboran Island, between 40 to776 m depth. The decapod crustaceans were identified to species level and quantified (abundance and biomass). Species richness (S), Shannon-Wiener diversity index (H’), evenness (J’) and functional diversity index was calculated after identifying and quantifying all decapods collected in each sample. A total of 84 species have been found, dominating the families Paguridae (14 spp), Inachidae (10 spp) and Pandalidae (8spp) in relation to number of species. The dominant species were Plesionika heterocarpus, Alpheus glaber and Calocaris macandreae, in terms of abundance and P. heterocarpus and Monadeus couchii in relation to biomass. Both depth and nature of the substrate characterized the different decapod assemblages. Functional diversity and J’ showed a positive correlation with depth, unlike abundance and biomass. On the continental shelf assemblages were dominated by a low number of species with high abundances, however those from the upper and middle slope showed higher evenness and a wide variety of functional groups. The Atlantic influence of the Alboran Sea favors the presence of a high number of species with Atlantic affinity.

The Gulf of Cádiz, located in the NE Atlantic Ocean, between the Iberian Peninsula and northern Africa, contains more than 50 mud volcanoes (MVs). MVs are seafloor edifices that result from the release of mud, brine and hydrocarbon fluids in areas with gas-rich over pressure sediments. These MVs are in different stages of seepage activity, bearing a broad diversity of chemosymbiotic and heterotrophic organisms. Some previous works focussed on the bryozoans from some areas of the Gulf of Cádiz (e.g. López de la Cuadra & García Gómez, 1994, Harmelin & d’Hondt, 1992a, b) however, information on bryozoans colonizing the different substrate types (bioclasts, authigenic carbonates, mud breccias) of MVs is almost nule. During 2010 and 2011 and within the framework of the INDEMARES-CHICA project, 25 samples were collected with beam trawl and benthic dredge at six MVs (Gazul, Almazán, Aveiro, Pipoca, Tarsis and Chica). Forty-five taxa belonging to 26 families and 31 genera were identified. Most taxa (39) was found in a single MV (Gazul) and others in several MVs, including the taxa Adeonellopsis, Palmicellaria, Tessaradoma, Reteporellina, and Schizomavella sp. 2. Several factors may influence the observed bryozoan biodiversity such as the sampling effort and sampling method used, the type and heterogeneity of substrates, and habitats as well as the depth. The identification to species level of the bryozoan material will improve the information on benthic communities of these MVs located in the recently established Site of Community Importance of “Volcanes de fango del Golfo de Cádiz”.

The seabed morphology and the sub-bottom characteristics of a sector of the Gulf of Cádiz continental slope have been analyzed from different data sets. The morphological characteristics, the type of sediments and dominant benthic species of Gazul mud volcano and adjacent areas have been studied. The morphological characteristics identified were grouped in fluid escape related features, bottom current features, mass movement features, structural features and biogenic related features. Additionally, dominant benthic species associated to fluid escape and seepage, hard substrates or soft bottoms have also been indicated in these features. A bottom current velocity analysis allowed relating the morphological features with the different sedimentary and oceanographic processes as well as the benthic habitats and that currently occur in the mud volcano and nearby areas. The major factor controlling these features and their associated benthic habitats is the interaction of deep water masses with the seafloor topography. At high velocities, authigenic carbonates can be exhumed and colonized by sessile suspensivorous species associated with hard substrates such as cold-water corals, anthipatarians and large sponges. Mounds and diapiric ridges are found on the depressions and they could be relict structures. Living corals have been found on raised zones, revealing different oceanographic condition and strong enough currents to favour the availability of nutrients and organic particles. Chemosymbiotic organisms are very scarce at the summit and old remains of Lucinoma asapheus indicating past higher seepage activity. Versión del editor

The Gulf of Cadiz display a wide continental shelf at its northwestern part with a complex oceanographic circulation, large extensions with soft bottoms, diapiric ridges, mud volcanoes, channels, that promote geological and biological heterogeneity and also a wide variety of commercial resources that are exploited by an important fishing sector. Fisheries activity in this area has been studied using VMS and logbooks data during 2011. Fishing effort and captures maps for some important species (Nephrops norvegicus and Parapenaeus longirostris) have been developed for different areas which may be able to improve the spatial and quantitative information on fisheries, and implement measures to improve ecosystem management and conservation of the different vulnerable habitats of the Gulf of Cadiz

The Alboran Sea displays oceanographic and biogeographical highlighting characteristics that promote one of the most important areas for marine biodiversity of the Mediterranean and European waters. Nevertheless, anthropogenic activities are threatening some coastal habitats that are highly important for species currently threatened or in danger of extinction (e.g. Patella ferruginea, Pinna nobilis). Consequently, new marine protected areas have been recently declared in the northern Alboran Sea in order to preserve species, habitats and ecosystems. The Sites of Community Importance “Calahonda” (Málaga) and “Acantilados y Fondos Marinos de Calahonda- Castell de Ferro” (Granada) contain Mediterranean characteristic habitats (e.g. Posidonia oceanica beds, coralligenous communities) with an important Atlantic faunistic component, as well as with protected species and others that are extremely rare or absent in other European locations. In addition, ecological processes that are representative of the Alboran Sea (e.g. upwellings, high productivity) take place in these areas, supporting the development of local artisanal fisheries.

The Bay of Málaga is located in a biodiversity hotspot with high productivity that favors a wide variety of commercial and non-commercial species as well as fishing fleet types. Benthic and demersal fauna from circalittoral soft bottoms of this bay have been studied using a benthic dredge (8 sampling stations in December 2013) and an otter trawl (8 sampling stations on a seasonal basis). Sediment and water properties have also been studied in order to analyze their relationships with the benthic and demersal communities. A total of 287 spp. have been found, being molluscs and fishes the most diverse and abundant ones in the samples. A low number of species (44 spp.) were only collected with both sampling gears, indicating the importance on combining sampling methods in biodiversity studies. Benthic dredge samples displayed some differences in relation to depth and sediment types, whereas differences of otter trawl samples seemed to be more influenced by seasonal changes. SIMPER analyses indicated that temporal variation was due to seasonal changes of abundance of some species of commercial interest. This seasonal variability should be taken into account in further management of this area as a potential new Fisheries Reserve.

Advances in remotely-sensed techniques have revolutionized mapping methods and our understanding of the seabed environment. In particular, multibeam backscatter data nowadays allows developing quantitative studies on the composition of the seafloor, which represents an important baseline for habitat mapping. Usually, the acoustic response is considered as a direct proxy of sediment texture, but seepage could affect significantly this relationship. A multibeam data set from the Gulf of Cádiz, was grouped using an ISO-cluster analysis and results were compared with 80 ground-truthing stations taken inside and outside cold seepage areas. Results show significant differences between the acoustic response of sediments with the same texture depending on the presence/absence of fluid emissions. Understanding this relationship is necessary to make image-based backscatter classification that allows the production of sediment and habitat maps in areas with extensive fluid emissions such as the Gulf of Cádiz.

Málaga Bay is an important area from the icthyoplankton viewpoint where it is possible to find more than 80 species belonging to 68 genera and 41 families. Furthermore, the bay is an essential spawning and nursery area for many species of commercial interest, such as sardine (Sardina pilchardus), anchovy (Engraulis encrasicolus), Atlantic horse-mackerel (Trachurus trachurus), Mediterranean horse-mackerel (T. mediterraneus) or hake (Merluccius merluccius). Local bottom trawl, purse seine and polyvalent artisanal fleets, have traditionally fished in this bay targeting on many species of fishes, crustaceans and molluscs. An ecological and fisheries study was undertaken in 2013 and 2014 with the purpose of assessing the suitability of Málaga Bay as a Fishery Protected Area. One of the important aspects taken into account is the spatial distribution of the fishing effort to evaluate its impact in the area. The findings achieved in this study are essential and valuable information for a proper fisheries management integrating the ecosystem-based approach into fisheries advice. The results show that Málaga Bay supports a heavy fishing pressure in all the fishing grounds which may affect both its commercial resources and sedimentary habitats.

Knowledge of the distribution and extent of seagrass habitats is currently the basis of management and conservation policies of the coastal zones in most European countries. This basic information is being requested through European directives for the establishment of monitoring programmes and the implementation of specific actions to preserve the marine environment. In addition, this information is crucial for the quantification of the ecological importance usually attributed to seagrass habitats due to, for instance, their involvement in biogeochemical cycles, marine biodiversity and quality of coastal waters or global carbon budgets. The seagrass atlas of Spain represents a huge collective effort performed by 84 authors across 30 Spanish institutions largely involved in the scientific research, management and conservation of seagrass habitats during the last three decades. They have contributed to the availability of the most precise and realistic seagrass maps for each region of the Spanish coast which have been integrated in a GIS to obtain the distribution and area of each seagrass species. Most of this information has independently originated at a regional level by regional governments, universities and public research organisations, which explain the elevated heterogeneity in criteria, scales, methods and objectives of the available information. On this basis, seagrass habitats in Spain occupy a total surface of 1,541,63 km2, 89% of which is concentrated in the Mediterranean regions; the rest is present in sheltered estuarine areas of the Atlantic peninsular regions and in the open coastal waters of the Canary Islands, which represents 50% of the Atlantic meadows. Of this surface, 71.5% corresponds to Posidonia oceanica, 19.5% to Cymodocea nodosa, 3.1% to Zostera noltii (=Nanozostera noltii), 0.3% to Zostera marina and 1.2% to Halophila decipiens. Species distribution maps are presented (including Ruppia spp.), together with maps of the main impacts and pressures that has affected or threatened their conservation status, as well as the management tools established for their protection and conservation. Despite this considerable effort, and the fact that Spain has mapped wide shelf areas, the information available is still incomplete and with weak precision in many regions, which will require an investment of major effort in the near future to complete the whole picture and respond to demands of EU directives. Versión del editor

The Alboran Sea is a transition region between the Mediterranean basin and the Atlantic Ocean containing a mix of Mediterranean and Atlantic species. The Strait of Gibraltar, at the west end of the Alboran Sea, connects the Mediterranean with the Atlantic Ocean. The Gulf of Vera also occupies a strategic location in the Western Mediterranean, representing a transition zone between the Alboran Sea and the rest of the basins with a more distinctive Mediterranean character. The Alboran Sea is one of the most productive areas of the Mediterranean, in contrast to the Gulf of Vera that displays a more oligotrophic character. Despite of the interest of the study area the information about the distribution of demersal fishes is scarce. In the present study, the main aim is to analyse diversity and distribution of demersal fish species of circalittoral and bathyal soft bottoms of the Alboran Sea (with a higher Atlantic influence and primary production) and the Gulf of Vera (with a higher Mediterranean influence and lower primary production). Sampling was carried out in the scientific trawl survey MEDITS (International bottom trawl survey in the Mediterranean) between 30 and 800 m depth. All samples were taken from Estepona and Cabo de Palos between 1994-2015 in the Alboran Sea and between 1995-2008 and 2014-2015 in the Gulf of Vera. (Figure 1). A total of 818 samples (687 from Alboran and 131 from Vera) were considered for this study. For each haul, the abundance and weight of individuals per fish species were standardised to 1 hour towing in order to calculate both species abundance (number of individuals per 1 hour towing) (ind•h−1) and biomass (g•h−1). In order to identify fish assemblages, ordination and classification multivariate methods using fish species abundance and biomass per haul matrices were applied. Prior to analyses, all data were logarithmically transformed using log(x + 1) to minimise the weighting of extreme abundance or biomass values of certain species. An analysis of similarities (ANOSIM) was carried out for statistical comparisons of groups of samples according to the different factors considered (depth, Alboran vs. Vera). Species rarefaction curves were used to compare the species richness values of each fish assemblage. In addition, for each group, Shannon-Wiener (H’) and Taxonomic distinctness (Δ*) diversity indices were calculated. For comparisons of the mean values of the considered variables (abundance, biomass and diversity indices) across the identified assemblages and years, we used a non-parametric Kruskal–Wallis test. A total of 231 fish species have been identified considering all samples, with 215 spp. collected from Alboran (3 classes, 25 orders and 75 families) and 160 spp.. from Vera (2 classes, 21 orders and 67 families), probably because the number of samples in the latter were lower. The number of occasional species, considering those that were captured only in 1 or 2 samples, were 56 in Alboran and 44 in Vera. The multivariate analyses (nMDS) indicated that depth is the main factor that determines the distribution of species in both areas, with four groups of samples displaying significant differences between them (ANOSIM-Alboran: R=0.85, p=0.001; ANOSIM-Vera: R=0.81, p=0.001). These groups were similar in both areas: Inner continental shelf (30-100 m), Outer continental shelf (101-200 m), Upper continental slope (201-500 m) and Middle continental slope (501-800 m) (Figures 2 and 3). Regarding the faunistic comparison between Alboran and Vera, the most acute differences were found between those samples from the Middle continental slope. These differences were evident for abundance (ANOSIM: R=0.81, p=0.001), biomass (ANOSIM: R=0.78, p=0.001) and species composition (presence-absence data) (ANOSIM: R=0.61, p=0.001). The trends for species rarefaction curves with depth was similar in both areas, with similar curves for the Inner and Outer continental shelf , a decrease of the species number for the Upper slope and finally the lowest number of species for the Middle slope. Likewise, the mean values of abundance, Shannon and Taxonomic indices also showed a similar pattern in both areas. Mean abundances differed significantly between assemblages increasing from the Inner shelf to Outer shelf and decreasing abruptly to the Upper and Lower slope (.minimum values). The Shannon diversity index showed significant differences in Alboran, but not in Vera, with minima in the Outer shelf in both areas. The taxonomic index also displayed significant differences in Alboran and Vera, with low values in the Inner shelf that increased abruptly to the Outer shelf and Upper slope, with a further acute increase in the Middle slope. Unlike for the other indexes, trends for mean the biomass values with depth were different in both areas. In Alboran biomass decreased from the Inner shelf to the Upper slope and increased to the Middle slope. Nevertheless, in Vera the biomass decreased with depth, with significant differences. In two sectors were evident significant differences. Regarding the interannual changes, the differences between years in Alboran were significant respect to species richness, abundance, biomass and Shannon diversity index. No clear increase or decrease trend was detected interannually. Unlike Alboran, in Vera, no significant interannual differences were detected. In conclusion: 1) Four main fish assemblages were detected on the continental shelf and slope in both areas that seem to be strongly linked to the depth gradient. 2) The middle slope showed the higher differences between both areas for abundance, biomass and presence-abundance data. 3) The species rarefaction curves, abundance, Shannon and Taxonomic diversity indices showed similar patterns with depth in both areas. Biomass index showed a different pattern, with maximum values in the Middle slope in Alboran and minimum ones in Vera.

En este trabajo se ha analizado la morfología del fondo, las características sub-superficiales y las comunidades bentónicas en el complejo Hespérides, situado en el talud continental del Golfo de Cádiz, con el objetivo de entender su relación con los procesos geológicos y oceanográficos, así como la influencia sobre los hábitats que se generan. Se han detectado especies bentónicas asociadas a escapes de fluidos, a sustratos duros y blandos en diferentes zonas del complejo. Los sedimentos de brecha fangosa y los organismos quimiosimbióticos se localizan en la cima de los conos volcánicos asociados a una mayor actividad de emisión. Los carbonatos autigénicos en los flancos y la base del edificio están relacionados con una actividad de expulsión de fluidos moderada, siendo desenterrados por las corrientes de fondo y colonizados por especies de sustratos duros. Las depresiones en la base están formadas por procesos de colapso, debido a escapes de fluidos activos bajo la influencia de las corrientes profundas. En general, los principales factores que controlan la morfología y las comunidades bentónicas asociadas son los procesos relacionados con escapes de fluidos, aunque no hay que despreciar el efecto de los procesos gravitacionales y la acción de las masas de agua profunda. Seabed morphology, sub-bottom characteristics and benthic communities of the Hespérides volcanic complex, located in the continental slope of the Gulf of Cadiz, have been analyzed. The aim of this study is to characterize the morphological features, the geological processes and near-bottom water masses for understanding the relationships between the occurrence of this fluid venting related edifice and their associated biota. Additionally, dominant benthic species associated with seepage, hard substrates or soft bottoms have also been observed in different areas of the complex. Mud breccia sediments and chemosymbiotic metazoans are mainly located at the summit indicating a higher seepage activity. Authigenic carbonates on the flanks and the base of the volcanic structure are related to a moderate seepage activity, being exhumed by bottom currents and colonized by hard substrate associated species. Adjacent depressions are linked to collapse processes as a result of the interplay of active fluid escape and bottom current effects. In general, major factors controlling these features and their associated biota are mud flow and fluid-escaperelated processes, although other factors such as gravitational and deep water masses related processes are also involved. LIFE+ INDEMARES/CHICA y ATLAS (EU Horizon 2020), Grupo PAIDI RNM-328. SUBVENT (CGL2012-39524-C02-01). Versión del editor 0,0000

Versión del editor 0,0000

Se ha analizado la morfología del fondo, las características sub-superficiales y los hábitats bentónicos de un sector del talud continental del Golfo de Cádiz. El objetivo es reconocer los tipos morfológicos y los procesos geológicos y oceanográficos para entender la relación con dichos procesos, así como su influencia sobre los hábitats y las especies bentónicas asociadas. Se han estudiado las características morfológicas, el tipo de sedimento y las especies bentónicas dominantes en cuatro estructuras volcánicas y en los fondos marinos adyacentes. Los tipos morfológicos identificados se han agrupado en formas relacionadas con escapes de fluidos desde el subsuelo, con corrientes de fondo, con movimientos en masa, formas estructurales y biogénicas. Además, se han identificado las especies bentónicas dominantes y asociadas a escapes de fluidos, a sustratos duros (costras de carbonatos autigénicos) y a sustratos blandos. Los principales factores que controlan la morfología y las comunidades bentónicas asociadas son los procesos relacionados con escapes de fluidos, aunque existen otros procesos, como los gravitacionales, y las propiedades de las masas de agua profunda. Los sedimentos de brecha fangosa y los organismos quimiosimbióticos se localizan principalmente en la cima de los edificios volcánicos, indicando que la actividad de expulsión de fluidos podría ser elevada en algunos casos. La presencia de coladas de fango y cuerpos lóbulados sobre los flancos son indicativos de un proceso de extrusión que tuvo lugar en diferentes fases. Los carbonatos autigénicos se han localizado en los flancos y en la base de las estructuras volcánicas y están relacionados con una actividad de expulsión de fluidos moderada, siendo desenterrados por la actividad de las corrientes de fondo y colonizados por especies de sustratos duros. Las depresiones en las zonas adyacentes están formadas por procesos de colapso, debido a escapes de fluido activos y bajo la influencia de las corrientes profundas. Seabed morphology, sub-bottom characteristics and benthic habitats of a sector of the Gulf of Cadiz continental slope have been analyzed. The aim is to recognize morphological features, geological processes and near-bottom water masses for understanding the relationships between the occurrence of fluid venting related edifices and their associated habitats and benthic communities. Morphological characteristics, sediment types and dominant benthic species of four volcanic structures and their adjacent areas have been studied. Identified morphological characteristics were grouped in fluid escape related features, bottom current features, mass movement features, structural features and biogenic related features. Additionally, dominant benthic species associated with seepage, hard substrates (authigenic carbonates) or soft bottoms have also been found in these features. A major factor controlling these features and their associated biota is mud flow and fluid-escape-related processes, although other factors such as gravitational and deep water masses related processes are involved. Mud breccia sediments and chemosymbiotic metazoans are mainly located at the summit indicating a higher mud flow and seepage activity. The presence of mass flows deposits and mud lobes on the flanks are indicative of mud extrusion process in different phases. Authigenic carbonates on the flanks and the base of the volcanic structures are related to a moderate seepage activity, being exhumed by bottom currents and colonized by hard substrate associated species. Adjacent depressions are linked to collapse processes, where active fluid escape and bottom current effects have been identified. Proyectos LIFE+ INDEMARES/CHICA y ATLAS (EU Horizon 2020). Grupo PAIDI RNM-328. Proyecto SUBVENT (CGL2012-39524-C02-01) Versión del editor

Posidonia oceanica is a Mediterranean endemic seagrass species that forms meadows covering ca. 2.5–4.5 millions of hectares, representing ca.25 % of the infralittoral and shallow circalittoral (down to 50m) bottoms of the Mediterranean. This seagrass is considered a habitat-engineer species and provides an elevated number of ecosystem services. In addition the Marine Strategy Framework Directive (MSFD, 2008/56/EC) includes seagrass like elements to evaluate the “Good Environmental Status” of the European coasts. Information about their phenological characteristic and structure of the meadows is needed for indicator estimations in order to establish their conservation status. The studied meadows are located in the westernmost limit of the P. oceanica distribution (North-western Alboran Sea) in the vecinity of the Strait of Gibraltar, an Atlantic-Mediterranean water transition area. Four sites were selected from East to West: Paraje Natural de Acantilados de Maro-Cerro Gordo (hereafter Maro), Special Area of Conservation “Calahonda” (hereafter Calahonda), Site of Community Importance Estepona (hereafter Estepona) and Punta Chullera (hereafter Chullera) where P. oceanica present their westernmost meadows. Phenological data were recorded from mid November to mid December in P. oceanica patches located at 2 – 3 m depth. At each site three types of patches (patch area 2 m2, large patches) were sampled. At each patch and site, 3 quadrants of 45 x 45 cm were sampled for shoot and inflorescences density measurements. In each quadrant, 10 random shoots were sampled for shoot morphology (shoot height and number of leaves). Shoot and inflorescences densities were standardized to squared meters. All the studied P. oceanica meadows develop on rocks and they present a fragmented structure with a coverage ranging between ca. 45% in Calahonda and Estepona and ca. 31% in Maro. The meadows of Chullera are reduced to a few small - medium patches with areas ranging between 0.5-1.5 m2 (Fig. 1). The meadows of Chullera and Estepona presented similar values of shoot density (ca. 752 – 662 shoots m-2, respectively) and leaf height (ca. 25 cm). Similarly, the Calahonda and Maro meadows also showed similar values of shoot density (ca. 510 – 550 shoots m-2, respectively) but displaying lower values than those of sites located closer to the Strait of Gibraltar. Regarding patch sizes and leaf height, the longest leaves (ca. 25 cm) were found in medium and large patches, but the number of leaves per shoot were higher in the small and the medium size patches (ca. 6.3 leaves per shoot). Flowering was only detected at the Calahonda meadows with maximum values of ca. 330 inflorescences m-2 (115.2 ± 98.2 inflorescences m-2, n= 9; mean ± SD) (Fig.1). Inflorescence density was not significant different among patches of different sizes. In the Alboran Sea and unlike the studied meadows, extensive beds of P. oceanica occur at the National Park of Cabo de Gata (northeastern Alboran Sea), but from east to west (Strait of Gibraltar), meadows are gradually fragmenting and their depth range decrease from 30m to 2m depth between Cabo de Gata and Chullera, respectively. Probably, the Atlantic influence and the characteristic oceanographic conditions of the Alboran Sea (i.e., higher turbidity, higher water turbulence) represent a developmental limiting factor for P. oceanica at higher depths. Similarities between the meadows located closer to Strait of Gibraltar (Chullera and Estepona) were detected as well as between those more distant (Calahonda and Maro). The first ones showed higher values of shoot densities and leaf heights than the formers, which could be relating to the higher hydrodynamic exposure found at Chullera and Estepona meadows. Regarding flowering events, sexual reproduction in P. oceanica is not common in different locations of the Mediterranean Sea. The available information seems to indicate that flowering represent an irregular event and it is related to high seawater temperature. In fact, the flowering episodes that occurred in Calahonda in November 2015, match with the warmest year ever recorded. This is the third flowering event registered in these meadows located close to the westernmost distributional limit of P. oceanica (Málaga, Alboran Sea), which could indicates that these meadows presents a healthy status. Furthermore, the absence of significant differences in relation to inflorescence density between patches of different sizes may be indicating that the fragmentation does not necessarily influence on the flowering of this seagrass species.

Mercator mud volcano has been explored by direct visual observations using a ROV at 350 to 370 m depth. Underwater images, taken mainly at the summit, have allowed characterizing the fluid venting environment, where different microforms, habitats and associated biota, with typical seepage components have been identified. Chemosynthetic bacterial communities were detected and sampled at the northeastern side of the summit at 350 m, next to pockmark-like depressions with diameters ranging 1 to 3 m, bioturbation marks, sediment mounds and authigenic carbonates of different sizes (0.1-5m length). Chemosynthesis-based communities were mainly composed by bacterial mats (patch diameter 10-30 cm), however some remains of cold seep chemosymbiotic bivalves (Lucinoma asapheus) were also found on the sediment. Habitat types at Mercator MV are influenced by oceanographic and sedimentation processes deposition and favouring fauna colonizing diverse substrate types, such as large sponges on slabs and sea-pens and annelids on soft bottoms.

Se ha analizado la morfología del fondo, las características sub-superficiales y los hábitats bentónicos de un sector del talud continental del Golfo de Cádiz. El objetivo es reconocer los tipos morfológicos y los procesos geológicos y oceanográficos para entender la relación con dichos procesos, así como su influencia sobre los hábitats y las especies bentónicas asociadas. Se han estudiado las características morfológicas, el tipo de sedimento y las especies bentónicas dominantes en cuatro estructuras volcánicas y en los fondos marinos adyacentes. Los tipos morfológicos identificados se han agrupado en formas relacionadas con escapes de fluidos desde el subsuelo, con corrientes de fondo, con movimientos en masa, formas estructurales y biogénicas. Además, se han identificado las especies bentónicas dominantes y asociadas a escapes de fluidos, a sustratos duros (costras de carbonatos autigénicos) y a sustratos blandos. Los principales factores que controlan la morfología y las comunidades bentónicas asociadas son los procesos relacionados con escapes de fluidos, aunque existen otros procesos, como los gravitacionales, y las propiedades de las masas de agua profunda. Los sedimentos de brecha fangosa y los organismos quimiosimbióticos se localizan principalmente en la cima de los edificios volcánicos, indicando que la actividad de expulsión de fluidos podría ser elevada en algunos casos. La presencia de coladas de fango y cuerpos lóbulados sobre los flancos son indicativos de un proceso de extrusión que tuvo lugar en diferentes fases. Los carbonatos autigénicos se han localizado en los flancos y en la base de las estructuras volcánicas y están relacionados con una actividad de expulsión de fluidos moderada, siendo desenterrados por la actividad de las corrientes de fondo y colonizados por especies de sustratos duros. Las depresiones en las zonas adyacentes están formadas por procesos de colapso, debido a escapes de fluido activos y bajo la influencia de las corrientes profundas. Seabed morphology, sub-bottom characteristics and benthic habitats of a sector of the Gulf of Cadiz continental slope have been analyzed. The aim is to recognize morphological features, geological processes and near-bottom water masses for understanding the relationships between the occurrence of fluid venting related edifices and their associated habitats and benthic communities. Morphological characteristics, sediment types and dominant benthic species of four volcanic structures and their adjacent areas have been studied. Identified morphological characteristics were grouped in fluid escape related features, bottom current features, mass movement features, structural features and biogenic related features. Additionally, dominant benthic species associated with seepage, hard substrates (authigenic carbonates) or soft bottoms have also been found in these features. A major factor controlling these features and their associated biota is mud flow and fluid-escape-related processes, although other factors such as gravitational and deep water masses related processes are involved. Mud breccia sediments and chemosymbiotic metazoans are mainly located at the summit indicating a higher mud flow and seepage activity. The presence of mass flows deposits and mud lobes on the flanks are indicative of mud extrusion process in different phases. Authigenic carbonates on the flanks and the base of the volcanic structures are related to a moderate seepage activity, being exhumed by bottom currents and colonized by hard substrate associated species. Adjacent depressions are linked to collapse processes, where active fluid escape and bottom current effects have been identified. Proyectos LIFE+ INDEMARES/CHICA y ATLAS (EU Horizon 2020). Grupo PAIDI RNM-328. Proyecto SUBVENT (CGL2012-39524-C02-01)

Habitat characterization using underwater images has been carried out in 4 mud volcanoes (Gazul, Almazán, St. Petersburg and Aveiro) and one mud volcano/diapir complex (Hespérides) located at the middle slope of the Spanish margin of the Gulf of Cádiz (360-1200m depth). A total of 126 species, mostly cnidarians, sponges, brachiopods, crustaceans and echinoderms and 19 habitats have been observed in the underwater images, including anoxic bottoms with cold seep fauna or remains (Siboglinum sp., Lucinoma asapheus, Solemya elarraichensis), bottoms with authigenic carbonates colonized by gorgonians and anthipatharians, extensive muddy bottoms with sea pens (Kophobelemnon sp., Protoptilum sp.) and bamboo corals (Isidella elongata) and cold-water coral banks (Madrepora oculata). Habitat type and distribution seem influenced by sedimentary features, presence of hard substrates with authigenic carbonates, seepage activity, depth and hydrodynamic conditions. Cold seep related species and heterotrophic species not directly linked to fluid venting represent seepage activity indicators and induce habitat and biodiversity differentiation among the fluid venting edifices.

In March 2014, the Spanish R/V Sarmiento de Gamboa equipped with the Portuguese multi-operational Remotely Operated Vehicle (ROV) "Luso 6000" explored and sampled five mud volcanoes of the Gulf of Cádiz during SUBVENT2 expedition. The explored mud volcanoes were Mercator, Yuma, Algacel, Mvseis and Madrid located offshore Moroccan Atlantic margin at water depths between 350 and 1650 meters. In addition, bathymetric data were acquired using the Atlas Hydrosweep DS multibeam echo-sounder and were processed with CARIS HIPS & SIPS yielding a bathymetric grid resolution of 15 m. The characterization of habitats and associated biota was based on high resolution videos and captured photographic material with MAGIX software as well as samples collected with the ROV. The observation was done during scanning the sea floor by TV camera at the altitude of 1-5 meters above the seafloor at low velocity of approximately 0.2-0.5m/s. Digital data analyses and their cartographical representation were performed with ArcMap 10.3.1 and Fledermaus. Underwater images allowed to characterize the occurrence of cold seeps with different seafloor micro-features, habitats and associated biota. Chemosynthetic bacterial communities, mainly occurring as bacterial mats (e.g., sulfate-oxidizing cf. Beggiatoa sp.), were detected, sampled and related to active bubbling seeps in pockmark-like depressions of different sizes. Sediment mounds and authigenic carbonates of different sizes (0.1-5 m length) were also detected in vent sites. Six different species of chemosymbiotic bivalves, including Lucinoma asapheus, Acharax gadirae, Solemya elarraichensis, Thyasira vulcoluatre, Isorropodon megadesmus and the deep water mussel Bathymodiulus mauritanicus displayed populations in the studied mud volcanoes. Hard bottoms with exhumated carbonate slabs seem to display a wider biodiversity and complexity, including large size sponges (e.g. Geodia, Phakellia), scleractinians (e.g. Caryophillia, Corallium, Madrepora), gorgonians (e.g. Bebryce, Chelidonisis) and antipatharians (e.g. Stichopathes) as well as different mobile associated species.. Habitat types of these mud volcanoes may be influenced by different oceanographic, sedimentation and venting processes resulting then in a broad biodiversity. SUBVENT project (CGL2012-39524-C02, MINECO, Spain), ATLAS project (EU, Horizon 2020) and EMEPC (Portugal)

En este artículo se presentan los resultados de la campaña ISUNEPCA_0814 cuyo objetivo principal es la estimación de la abundancia de cigala a partir de imágenes submarinas. El método se basa en el hecho de que esta especie vive en el interior de madrigueras que pueden ser identificadas y cuantificadas en un área conocida, obteniéndose una estimación de la densidad de madrigueras que puede ser usada como un índice de abundancia del stock. Este tipo de campañas son una excelente plataforma para la caracterización y cartografiado de hábitats bentónicos, monitoreo de la biodiversidad marina y evaluación del impacto de la pesca sobre el sustrato. En este sentido, las imágenes submarinas han permitido caracterizar los hábitats presentes, cuantificar la abundancia de otras especies macrobentónicas en el área de distribución de la cigala y su relación con variables ambientales como la temperatura, salinidad, MO, y composición granulométrica. Versión del editor

The analysis of a data set of multibeam bathymetry plus high resolution seismic and parametric profiles allow us to characterize the geomorphologic units on the Alboran Sea-floor as well as the evolution of morpho-sedimentary systems along the Pliocene and Quaternary, later than the main erosive Messinian event. Since the opening of the Gibraltar Straits, the sedimentary evolution of this basin has been controlled by the interchange of water masses between the Atlantic Ocean and the Mediterranean Sea. Basin physiography is also a consequence of the Pliocene-Quaternary compression which has progressively uplifted the sourrounding reliefs and deforms the interior and the margins of the basin. On this scenario, several submarine canyons and gullies have been developed in this basin which traverse especially the northern margin and the flanks of the Northern Alboran Ridge, without affecting the African margins. This fact must be related to the action of bottom contour currents which constitute the main morpho-sedimentary process. The influence of water masses distributed the sedimentary input carried by rivers and coming from the erosion of surrounding ranges. In the southern margin of this basin this influence is stronger and inhibits the development of transversal submarine canyons.

European anchovy recruitment to the Guadalquivir estuary mainly occurs when the environmental conditions show more stability. Unusual changes in the environmental conditions of this estuary negatively impacted on key preys of anchovy and therefore on its nursery function. In this way, nutritional condition should determine strongly the physiological state of this species in estuaries and thus its survival and recruitment. RNA:DNA ratio has been applied with success as indicator of nutritional condition and growth in marine organisms. We study RNA:DNA ratio in anchovies of the coupled system Guadalquivir estuary-coastal influenced area in the Gulf of Cádiz in order to evaluate the condition seasonal variability of this species along this spatial gradient. Spatial differences in the size distribution of anchovy and high values of RNA:DNA in the Guadalquivir estuary compared to its influence coastal area suggest that anchovies migrate to the estuary and they acquire a very good condition. We conclude that RNA:DNA is an useful tool to understand the ecological mechanisms by which the coupled system Guadalquivir estuary-coastal influenced area in the Gulf of Cádiz control the success or failure of the recruitment of this important fishery resource in the region.

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Informe de la campaña oceanográfica INDEMARES CHICA 0211, realizada a bordo del Cornide de Saavedra entre febrero y marzo de 2011. En esta campaña hemos centrado nuestra actividad en la zona del Caladero de pesca del Laberinto, al norte, frente a Cádiz, y en la zona de los Volcanes de Fango del campo Hespérides, al sur, frente al Estrecho de Gibraltar.Las zonas de trabajo se sitúan en el talud continental del margen del Golfo de Cádiz, frente a las localidades de Chipiona y Cádiz, para el Caladero de pesca del Laberinto, y frente a Barbate y Tarifa para la zona de Volcanes de Fango del campo Hespérides.