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Esponjas lithistidas de cuevas submarinas en el Mediterráneo: su taxonomía y relaciones. – Se describen varias esponjas lithistidas procedentes de cuevas del noroeste del mar Mediterráneo y de las cuencas del mar Adriático. Dentro de las esponjas incluidas en la familia Corallistidae, Neoschrammeniella bowerbanki y Neophrissospongia nolitangere, se registran por primera vez en el Mediterráneo y Neophrissospongia radjae n. sp. y Neophrissospongia endo- umensis n. sp. se describen como nuevas especies. Dentro de la Familia Theonellidae, la esponja común, que hasta la fecha se había identificado como Discodermia polydiscus se describe como Discodermia polymorpha n. sp. Ejemplares fósiles de la cueva de los 3PP se asignan provisionalmente a Neoschrammeniella bowerbanki. Se discute la distribución y afinidades de la fauna de las lithistidas. Several lithistid sponges are described from Mediterranean caves occurring in the northwestern and Adriatic basins. In the Corallistidae, Neoschrommeniella bowerbanki and Neophrissospongia nolitangere are recorded for the first time from the Mediterranean, whereas Neophrissospongia radicle n. sp. and Neophrissospongia endoumensis n. sp. are described as new. In the Theonellidae, the common sponge previously identified as Discodermia polydiscus is described as Discodermia polymorpha n. sp. Fossil specimens from the 3PP cave are tentatively attributed to Neoschrammeniella bowerbanki. The distribution and affinities of this lithistid fauna are discussed.

Este trabajo presenta una nueva aproximación al diagnóstico de la sobrepesca de reclutamiento. Nuestra hipótesis consiste en que la condición de los reclutas debe aumentar cuando suceden fallos en el reclutamiento debidos a la actividad pesquera. Esto sería una consecuencia del incremento en la disponibilidad de recursos tróficos debido a que la población es más reducida que la que el ecosistema podría soportar. Se calcularon series temporales de condición de reclutas de merluza a partir de datos recogidos en las campañas MEDITS en las sub-áreas geográficas (GSAs) 1, 6, 17 y 19 entre los años 1994 y 2015. Se utilizó la regresión lineal múltiple para analizar la relación entre la condición media anual y la abundancia de reclutas e índices climáticos en cada GSA. Solo se detectaron correlaciones significativas en la GSA 6, dónde el 69% de la variabilidad en la condición se explica por la correlación negativa con la abundancia de reclutas, y con dos índices climáticos, la Oscilación del Mediterráneo Occidental y la anomalía estandarizada de la temperatura del aire en superficie en el Golfo de León. A pesar de las diferencias en la abundancia de reclutas entre GSAs, su condición anual media osciló alrededor de un mismo valor basal durante la mayor parte de la serie temporal, sugiriendo que las tasas de mortalidad denso-dependiente son un mecanismo importante para la estabilización del reclutamiento de merluza en niveles próximos a la capacidad de carga cuando las poblaciones no sufren sobrepesca de reclutamiento. Este patrón cambió cuando la tendencia decreciente de la abundancia de reclutas elevó los valores de condición en la GSA 6 por encima de los del resto de GSAs de forma persistente. De acuerdo con nuestra hipótesis, la merluza de la GSA 6 se encuentra en sobrepesca de reclutamiento. A new approach to recruitment overfishing diagnosis is presented. We hypothesize that condition of recruits should increase when recruitment failures are caused by fishing activity. This would be a consequence of the increase in trophic resource availability, because the population is smaller than that which the ecosystem could support. Temporal series of hake recruit condition were calculated from MEDITS survey data collected in Mediterranean geographical sub-areas (GSAs) 1, 6, 17 and 19 from 1994 to 2015. Multiple linear regressions were used to analyse the relationship between mean annual condition and abundance of recruits and climatic indices in each GSA. Significant correlations were only detected in GSA 6, where 69% of condition variability was explained by the negative correlation with recruit abundance, and with two climatic indices, the Western Mediterranean Oscillation and the standardized air temperature anomaly at surface from the Gulf of Lions. Despite the differences in recruit abundance among GSAs, their mean annual condition oscillated around the same basal value during most of the time series, pointing to density-dependent mortality rates as an important mechanism stabilizing hake recruitment to levels close to the carrying capacity when populations do not suffer recruitment overfishing. This pattern changed when the decreasing recruit abundance trend drove GSA 6 condition values persistently above those of the rest of the GSAs. According to our hypothesis, hake in GSA 6 is in recruitment overfishing.

The high species richness, coupled with high proportion of endemism, makes the Mediterranean one of the world’s ‘biodiversity hotspots’. However, the continuous increase in fisheries in the last few decades has led to the overexploitation of their main commercial stocks. Using fishery-independent data collected under the framework of the MEDITS trawl surveys carried out over the last 20 years, we study the demersal fish diversity pattern in the Mediterranean at a large spatial and temporal scale to determine whether it is being affected by the general fishing overexploitation of the demersal resources. The detected diversity trends are compared with the spatio-temporal variation in bottom trawl fishing effort in the Mediterranean. Our results show a stability and even recovery of demersal fish diversity in the Mediterranean together with higher diversity values on the continental shelves of the Balearic Islands, Sardinia, Sicily and the Aegean Sea. At large temporal and spatial scales, the high diversity of demersal assemblages in the Mediterranean is associated with a reduction in bottom trawl fishing effort. The inclusion of species other than target ones through diversity indices is important in the implementation of an ecosystem-based fisheries management. Sí

Se investigaron las características de la distribución de dos de los crustáceos decápodos más importantes a nivel comercial del mar Mediterráneo, la gamba de altura, Parapenaeus longirostris y la cigala, Nephrops norvegicus, en aguas mediterráneas europeas. El presente estudio se basa en datos recopilados en las campañas de pesca experimental de arrastre MEDITS, relizadas de 1994 a 2015 desde el estrecho de Gibraltar hasta la cuenca levantina nororiental (aguas de Chipre). Las diferencias observadas en el patrón de distribución se pueden interpretar como distintas respuestas a factores ambientales relacionados con los diferentes rasgos del ciclo vital de las dos especies. De hecho, N. norvegicus es una especie bentónica de vida larga, con bajas tasas de crecimiento y mortalidad, mientras que P. longirostris es una especie epibentónica de vida corta, caracterizada por tasas más altas de crecimiento y de mortalidad The main characteristics concerning the distribution of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, the deep-water rose shrimp, Parapenaeus longirostris, and the Norway lobster, Nephrops norvegicus, are studied in the European Mediterranean waters. The study is based on data collected under the MEDITS trawl surveys from 1994 to 2015 from the Gibraltar Straits to the northeastern Levantine Basin (Cyprus waters). The observed differences can be interpreted as different responses to environmental drivers related to the differing life history traits of the two species. In fact, N. norvegicus is a long-living, benthic burrowing species with low growth and mortality rates, while P. longirostris is an epibenthic, short-living species characterized by higher rates of growth and mortality

The Mediterranean Sea shows a trend of increasing temperature and decreasing productivity from the western to the eastern basin. In this work we investigate whether this trend is reflected in the cephalopod assemblages found throughout the Mediterranean. Data obtained with bottom trawl surveys carried out during the last 22 years by EU Mediterranean countries were used. In addition to analysing spatial differences in cephalopod assemblages, we also analysed putative temporal changes during the last two decades. For this purpose, the basin was spatially divided into bioregions, the trawling grounds were subdivided into depth strata, and the dataset was split into two time series of 11 years each. All analyses were done using PRIMER software. The species richness did not vary with the longitudinal gradient, though in most bioregions it showed a mild decrease with depth before plummeting in the deepest waters. Cluster analysis revealed four different bathymetric assemblages in all bioregions. Despite the contrasting conditions between basins and the claims of biodiversity loss, our study revealed that spatial and temporal differences during the last two decades were restricted to changes in the relative abundance of species from a common pool of species inhabiting the whole Mediterraneans from a common pool of species inhabiting the whole Mediterranean.species from a common pool of species inhabiting the whole Mediterranean. Evaluación de Recursos Demersales por métodos directos en el área 1 y 2 del GFCM MEDITS SI

Marine litter is one of the main sources of anthropogenic pollution in the marine ecosystem, with plastic representing a global threat. This paper aims to assess the spatial distribution of plastic macro-litter on the seafloor, identifying accumulation hotspots at a northern Mediterranean scale. Density indices (items km–2) from the MEDITS trawl surveys (years 2013-2015) were modelled by generalized additive models using a Delta-type approach and several covariates: latitude, longitude, depth, seafloor slope, surface oceanographic currents and distances from main ports. To set thresholds for the identification of accumulation areas, the percentiles (85th, 90th and 95th) of the plastic spatial density distribution were computed on the raster data. In the northern Mediterranean marine macro-litter was widespread (90.13% of the 1279 surveyed stations), with plastic by far the most recurrent category. The prediction map of the plastic density highlighted accumulation areas (85th, 90th and 95th percentiles of the distribution, respectively, corresponding to 147, 196 and 316 items km–2) in the Gulf of Lions, eastern Corsica, the eastern Adriatic Sea, the Argo-Saronic region and waters around southern Cyprus. Maximum densities were predicted in correspondence to the shallower depths and in proximity to populated areas (distance from the ports). Surface currents and local water circulation with cyclonic and anticyclonic eddies were identified as drivers likely facilitating the sinking to the bottoms of floating debris Sí

The methodological approach to data collection and analysis in Mediterranean bottom trawl surveys has changed considerably since their beginnings in the mid- 1980s. The introduction of new technologies in surveys greatly improved knowledge on trawl underwater geometry, but also raised a question on the reliability of the data obtained. The most commonly used trawl monitoring systems in the Mediterranean use the constant speed of sound when calculating horizontal distance from one sensor to another. However, the speed of the sound in seawater is not constant because it depends on water temperature, pressure, and salinity. This is known to affect the performance of the horizontally transmitting sonars, and it is reasonable to assume that unless it is properly compensated for, the readings from trawl monitoring systems can be incorrect, resulting in biased swept area estimates, and hence potentially producing bias in abundance estimates. In the knowledge that speed of sound depends on temperature, salinity and pressure, the Del Grosso (1974) equation was used to calculate the compensation coefficient for a series of theoretical depth and temperature data. A simple model is proposed in the current paper for the manual correction of the horizontal net opening and swept area estimates. Temperature and depth data obtained from the MEDATLAS project are used to show seasonal and spatial variation in the near- bottom speed of sound, and the results demonstrate that, unless compensated for properly, the error in the horizontal net spread ranges from –1.5% to 2.9%.