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DEMERsal ecosySTEMs, DEMERSTEM

Species of the Sternoptychidae teleost family display an impressive morphology, including their extreme reduced size. Here, we report the first mitochondrial genome of the diaphanous hatchet fish Sternoptyx diaphana. By using short-read sequencing Illumina HiSeq, we generated two mitochondrial contigs which were later physically assembled by PCR. The mitochondrial genome of S. diaphana was 17,224 bp in length (excluding the control region) and is composed of 13 PCGs and 2 ribosomal RNA genes. Strikingly, we could not identify the tRNA-Phe and two copies of tRNA-Met were differently positioned. Additionally, the mitogenome displays a completely new gene rearrangement among vertebrates. We expect that the study presented here will pave the way for further molecular studies with this underrepresented group of illusive teleost fish.

Highly migratory Atlantic bluefin tuna (ABFT) is managed as two stocks, Western and Eastern. Western ABFT spawn mainly in the Gulf of Mexico (GOM) and Eastern ABFT in the Mediterranean Sea (MED) (1). Understanding connectivity between ABFT populations is important for conservation and management of this valuable fishery resource that has been exploited for centuries. ABFT are highly mixed, with multiple disciplines supporting weak structuring between Western and Eastern stocks (1). Concerning genetics, subtle structuring of ABFT populations across the Atlantic Ocean has been the conclusion of studies describing genetic tools for traceability (2,3). Larval fish provide the genetic signal of successful breeders and have occasionally been genetically characterized with juveniles (young-of-the-year, YOY) collected in nursery areas. For the first time, cooperative field collection of tuna larvae during 2014 in the main spawning area for each stock enabled us to assess the structuring of ABFT genetic diversity in a precise temporal and spatial frame exclusively through larvae (5). Partitioning of genetic diversity at nuclear microsatellite loci and in the mitochondrial control region resulted in low significant fixation indices. Individual-based clustering analysis of larval ABFT genetic diversity indicate apparent connectivity between the GOM and MED spawning grounds that could support the hypothesis of mixing of breeders belonging to different stocks., ECOlogía trófica comparativa de LArvas de aTUN rojo atlántico (Thunnus thynnus) de las áreas de puesta del Medterraneo-NO y el Golfo de México., This collaborative study was supported by "ECOLATUN" PROJECT CTM2015-68473-R (MINECO/FEDER) funded by Spanish Ministry of Economy and Competitiveness; "TUNAGEN" project funded by IEO; and "BLUEFIN" project financed by IEO and Balearic Island Observing and Forecasting System (SOCIB). This research was funded by NASA (NNX11AP76G S07), the NOAA National Marine Fisheries Science Service through the Southeast Fisheries Science Center, as well as by Cooperative Institute for Marine and Atmospheric Studies under Cooperative Agreement NA15OAR43200064 at the University of Miami. There was no additional external funding received for this study. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the author(s) and do not necessarily reflect those of NOAA or the Department of Commerce., ECOLATUN

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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

LETSHAKE AGL2013-4846-R

The European hake is one of the major commercially important species in Western Europe fisheries. Currently its management is divided into different functional units in the Mediterranean (GFCM, General Fisheries Commission for the Mediterranean) and two stocks in the Atlantic: the Southern and the Northern Stock. The basis for the definition of this management stock structure is under permanent discussion and in the latest years there were an increased amount of genetic studies addressing this topic. Integrated ecosystem assessment requires an improved understanding of the marine ecosystem to provide an effective advice. To this end we have gathered hake genetic information from different studies with the aim of developing a spatial assessment model that links the current stocks. These studies show a restricted gene flow between Southern hake and Mediterranean hake, although a smaller genetic distance between Southern and Northern stocks than one expected from two independent populations, suggesting the presence of a major gene flow from northern grounds core stock (Porcupine and Great Sole Banks) towards the Bay of Biscay and the northwest coast of the Iberian Peninsula. However the quantitative implementation of genetic metrics (such as Fst, migration rates, etc) into population dynamic models is not straightforward given the different nature and assumptions behind these different approaches. In this work we discuss the problems to link these different disciplines suggesting ways to overcome them. These include ways to improve future genetic sampling and developing plausible scenarios for genetic connectivity in population dynamic models.

La merluza europea Merluccius merluccius (Linnaeus, 1758) se distribuye sobre la plataforma continental europea desde las costas escandinavas hasta Mauritania y el Mediterráneo (Casey y Pereiro, 1995). Es una especie de gran demanda comercial y aunque en los últimos años ha estado sometida a un gran esfuerzo pesquero, actualmente es un recurso abundante en aguas españolas. Esta abundancia está íntimamente relacionada con el reclutamiento y este por motivos todavía desconocidos, varía cíclicamente. Este hecho, junto con su creciente demanda para consumo humano, ha acrecentado el interés de diversos países de la Unión Europea en investigar la potencialidad de su cultivo integral. Al ser una especie demersal, es decir de profundidad, existe una gran difi cultad en la obtención de individuos vivos y en óptimo estado para su posterior adaptación a la cautividad, ya que como consecuencia del cambio de presión, se produce una dilatación de la vejiga natatoria al subirlos a superfi cie, lo cual causa un efecto muy traumático en los peces.

The European hake is a top predator which first feeding preferences are largely unknown, despite being suspected that certain prey species and sizes are preferred. This knowledge is relevant for exogenous hatchery food supply during early life stages of hake, but remains elusive due to the difficulty of maintaining, spawning and harvesting hakes (Iglesias et al. 2010) to properly test its natural diets. Post-hatching early stages of hake are believed to feed at low light intensities associated to the deep water column, so testing parallel experimental designs of light-intensity vs. preys are key to undertake this species’ domestication. We examined in vitro prey preference, prey density and mortality of starved 7-8 DPH hake larvae under 12 zooplankton-based diets.

The European hake is a top predator which first feeding preferences are largely unknown, despite being suspected that certain prey species and sizes are preferred. This knowledge is relevant for exogenous hatchery food supply during early life stages of hake, but remains elusive due to the difficulty of maintaining, spawning and harvesting hakes (Iglesias et al. 2010) to properly test its natural diets. Post-hatching early stages of hake are believed to feed at low light intensities associated to the deep water column, so testing parallel experimental designs of light-intensity vs. preys are key to undertake this species’ domestication. We examined in vitro prey preference, prey density and mortality of starved 7-8 DPH hake larvae under 12 zooplankton-based diets.

Optimal light characteristics are species-specific in aquatic environment. Each species needs a minimal threshold intensity to develop normally and grow, which is probably related to the aptitude to localize and catch preys. The synergistic effect of food availability-day-length appears to be determining at this stage. Long day-length stimulates growth, influences early maturation and improves larval rearing quality. However, a few species are able to develop and grow at very low light intensities or in the absence of light (Boeuf & Le Bailr 1999). In this study we tested feeding efficiency of hake larvae under various light conditions and tank background.

Senegalese sole (Solea senegalensis) is a species of great interest in aquaculture because it has a high commercial value and a fast development of eggs. The reproduction of Senegalese sole in captivity has been studied since the early 1980s (Rodriguez et al., 1982). While F1 females were shown to be able to produce fertilized eggs from natural spawning as long as they were accompanied by wild males (Mañanos, 2011), failure of F1 males to display normal courtship behaviour has been demonstrated (Carazo et al., 2009). The reason for this failure remains unclear and therefore, research in this subject is paramount to overcome this bottleneck in S. senegalensis culture. We have designed an experiment using two broodstocks maintained since 2010 in the aquaculture facilities of the Oceanographic center of Vigo, one of them (T1) constituted by wild females together with wild and F1 males and the other (T2) constituted by F1 females together with wild and F1 males. One year later we obtained a successful spawn in T2. The main goal of this research was to test whether the male responsible for this spawn was F1.

The wreckfish Polyprion americanus is a long-living pelagic fish with a demersal adult phase that shows an antitropical distribution. In the Eastern Atlantic, juvenile and adult wreckfish are found off from the Norwegian coast to Southern Africa including shallow portions of the Mid-Atlantic ridge and associated islands (Macaronesian Islands) and the Mediterranean Sea (Sedberry et al. 1999). This species is a promising candidate for aquaculture and consequently it has recently been brought to Galician hatcheries for domestication (Peleteiro and Rodríguez, 2012). It is well known that domestication and management of hatchery stocks require an adequate strategy for the initial broodstock foundation and its further reproductive management. Therefore the combination of genetic markers with classic domestication strategies seems to be a useful approach to skip both genetic drift and consanguineous adverse effects. New microsatellite markers have been isolated for ecumenical tasks in this species and applied them to assess the genetic status of the four wreckfish stocks being harvested in Galician hatcheries as compared to the genetic diversity present in its source population from the Eastern Atlantic. Additionally, we aimed to predict the success of different reproductive strategies upon the in silico simulation of F1 and F2 progenies from each stock.

In the last years, the marine aquaculture research group of the Oceanographic Center in Vigo is endeavoured with completing the life cycle of both, the European hake (Merluccius merluccius) and the Octopus (Octopus vulgaris) using different approaches. One identified bottlenecks for both species is the development stages of larvae and paralarvae which is probably related to nutrition. More research in this field is a key issue to overcome many culture problems. As far as we know, feeding larvae/paralarvae with wild zooplankton improves significantly their growth rate and survival. There are two key issues in this research to identify prey preferences for hakes and octopuses, first, to accomplish the molecular identification of zooplankton species present in Ría de Vigo and the second one, the use the sequences obtained to design specific primers for each species and apply them to identify the species present in the stomachs of hake larvae and Octopus paralarvae. The main goal of this research is two identify the natural zooplankton preys from Ría de Vigo using a molecular approach.

In this study we have tracked the internal transcribed spacer ITS1-rDNA in temporal hake samples (1976, 2000 – 2005 and 2007) to study its molecular behaviour throughout the overexploitation history of this fishery. Ninety-eight ITS1 haplotypes were recovered out of 304 sequences from 105 individuals. The haplotype MmITS1.1 valued 50.3% in the global dataset and was the most frequent one up to 2007 when frequency of a secondary haplotype MmITS1.2 overwhelmed it (39.3%). Ninety percent of haplotype involved rare variants (less than 1% each) and were cohort-specific without significant differences in their abundance across years. Molecular networks per year are congruent with the recent history of this fishery as well as with phenomena depicted using microsatellite data. All data indicate that the Atlantic hake population is recovering from a history of overexploitation, for strict neutral markers as well as for pseudo-selective ones.

The wreckfish Polyprion americanus is a long-living pelagic fish with a demersal adult phase that shows an antitropical distribution along the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Previous genetic studies have suggested a significant differentiation between North Atlantic and South Atlantic populations using mitochondrial DNA and microsatellite markers. Nevertheless it remains elusive whether further structuring exists within the apparently homogeneous north Atlantic stock. We have applied neutral microsatellite markers to temporal wreckfish samples from the whole north Atlantic in order to clarify the above scenario. Experimental data showed a global 12.7% differentiation among samples mainly due to divergence among three different gene pools: North Atlantic, South Atlantic and Oceania. However, Atlantic populations seem to be systematically connected through longitudinal migrations from Caroline waters to south-western Euro-African waters. This result is key to understand wreckfish population dynamics as well as to properly design its exploitation rules.

Embryonic development of O. vulgaris has been thoroughly described in literature (Naef 1928, Iglesias 2004). Naef (1928) described twenty different stages of embryonic development, classified according to their morphological characteristics. The inner yolk sac begins in the embryo at the Naefs stage XV of embryonic development. According to Boletzky (2010), this yolk mass passes through the bloodstream into the digestive system in order to form a nutritive reserve (the inner yolk sac) which provides the newly born paralarvae the possibility to obtain the energy required during the first days of life, although Octopus paralarvae begin to feed immediately after hatching (Iglesias et al, 2006). The effect of temperature on the embryonic development of cephalopods is well documented (Boletzky, 1987). However, with a few exceptions there are no data on the effect of temperature on survival and rate of yolk utilization in cephalopod hatchlings. The main goal of this work was to describe the use of outer yolk and its transference to the inner yolk sac during the last stages of the embryonic development of O. vulgaris, as well as the use of inner yolk by unfed paralarvae during the first 4 days at 14ºC and 18ºC and how this fact affect on the control of energy expenditure, growth and weight loss of the paralarvae.

The European hake Merluccius merluccius is a demersal fish that exhibits high growth rate and has an important market value (Lloris et al., 2005). Those properties together with the overexploitation of its Atlantic fishery make this species a promising candidate for marine aquaculture (Engelsen et al., 2007). This species is at its very early stages of domestication the unique world stock being harvested at the Spanish Institute of Oceanography (Iglesias et al., 2010). Early steps of domestication require conjugation of population genetic criteria to skip founding effects and monitoring reproductive schemes of cultured stocks. On the one hand, the population genetic background of the donor Atlantic population is well known after wide range studies using different markers (e.g. Pita et al., 2011). On the other hand, little is known on the reproductive behaviour of this species or on the genetic load of the European hake stock maintained at the Spanish IEO facilities (Vigo, Spain).

Durante el desarrollo embrionario el órgano vitelínico mueve el aparato circulatorio del embrión y las reservas del vitelo externo al torrente sanguíneo (Boletzky, 2010). A partir del estadio XV de Nael (Nael, 1928) las reservas se acumulan en el saco vitelino intemo cuyo volumen aumenta hasta la eclosión (Boletzky, 2010). Tras ella, las paralarvas utilizan esas reservas como alimento endotrófico combinado con la alimentación exotrófica. la presencia de saco vitelino extemo indica una eclosión prematura y la pérdida de éste aumenta la tasa de mortalidad en las crías (Okubo, 1979). El objetivo de este trabajo lue mostrar la importancia del proceso de absorción y acumulación de vitelo externo dentro del saco vitelínico interno para el control de gasto energético, el crecimiento y perdida de peso. Para ello, se diseñó un experimento a dos temperaturas (14'C y 18'C) donde se incubaron dos puestas hasta la eclosión, midiendo la acumulación de vitelo en el saco interno. Tras la eclosión, las paralarvas se mantuvieron en inanición durante cinco días a las temperaturas de incubación y se controló el peso durante ese periodo. Se observaron dilerencias signilicativas (p

El gran valor comercial y organoléptico de la merluza europea (Merluccius merluccius) junto con su sobreexplotación en las últimas décadas,la convierten en una candidata potencial en acuicultura marina. Partiendo de 476.747 secuencias de una genoteca del transcriptoma de merluza europea, se caracterizaron 200 microsatélites, de los cuales 1610ci (2 tetranucleótidos, 8 trinucleótidos y 6 dinucleótidos), se combinaron en peA· múltiplex junto con cinco marcadores previos para el genotipado sistemático de poblaciones y stocks domésticos de merluza (lEO-Vigo). Su aplicación a 192 merluzas salvajes representativas de su rango natural muestran que este conjunto de microsatélttes derivados de EST son una herramienta genética potente, tanto analítica como estadisticamente. Además, la homologia de la secuencia de algunos clones con genes expresados en otras especies, puede pemnír la selección asistida por marcadores de genes candidatos, además del manejo reproductivo del stock de merluza. The high commercial and organoleptic value 01 the European hake (Merluccius merluccius) together with its overexploitation during lhe last decades, make this species a promising candidate to marine aquaculture.ln this study we have screened 476,747 sequences Irom a transcriptome library 01 the European hake. Sixteen microsatellite loci (2 tetranucleotides, 8 trinucleotides, 6 dinucleotides) out 01two·hundred ones tested were selecled and multiplexed with live previous markers lorthe systematic genotyping 01 populations and hatchery hake stocks (IEO·Vigo). Multiplexes testing on 192 wild hakes showed that this EST-derived microsatellite set is analytically and statistically powerful regarding its polymorphism and would allow marker assisted seleclion olcandidate genes in this species.