Asociaciones de peces profundos en el Mediterráneo

[EN] Data collected during the DESEAS survey carried out in three areas of the Mediterranean Sea (Balearic Sea, western and eastern Ionian Sea) were used to describe the structure and spatial distribution of the fish assemblages at depths between 600 and 4000 m. A total of 55 species (8 chondrichthyes and 47 teleost fish) were sampled, 38 of them in the Balearic Sea, 30 in the western Ionian and 37 in the eastern Ionian. Multivariate analysis showed a clear pattern of zonation with depth and geographic area. Three main assemblages were identified across the vertical gradient investigated: on the upper slope around a depth of 600 m, on the middle slope between 800 and 1300 m, and on the lower slope below 1300 m. The geographic characterisation of the ichthyofauna structure was mainly observed on the upper and middle slope. The highest abundance and biomass values were found at depths of 1000-1200 m due to the presence of larger species with high energy requirements, such as Alepocephalusrostratus, Mora moro and Galeus melastomus. On the middle slope, significant differences in the abundance, biomass and mean fish weight were detected between the three areas. Significant differences for these parameters were also shown between the middle and lower slope assemblages. A significant decrease in species richness and diversity was shown with increasing depth, indicating an impoverishment of the megafauna with depth and a higher similarity between the Balearic Sea and the Ionian Sea with regard to the greatest depths. The dominant species on the deepest bottoms were Bathypteroismediterraneus, Chalinura mediterranea and Coryphaenoides guentheri. On the lower slope, the shark Centroscymnuscoelolepis was also found to be relatively abundant off the Balearic Islands, Etmopterusspinax in the eastern Ionian Sea and the teleost fish Cataetyx laticeps throughout the three study areas. The deepest bottoms of the Mediterranean Sea shelter an ichthyofauna dominated by small-medium species living in a food scarce environment in which some large mobile fishes are widespread. The results are discussed in relation to previous studies mostly carried out in the Atlantic and western Mediterranean[ES] A partir de datos recolectados durante la campaña DESEAS, llevada a cabo en tres áreas del mar Mediterráneo (Mar Balear y Iónico occidental y oriental), se describe la estructura y la distribución espacial de las asociaciones de peces entre 600 y 4000 m de profundidad. Se obtuvieron un total de 55 especies (8 condrictrios y 47 peces teleósteos), 38 de los cuales procedían del mar Balear, 30 del Iónico occidental y 37 del oriental. El análisis multivariante de los datos nos muestra un claro patrón en zonación tanto en profundidad como por área geográfica. Se identificaron tres asociaciones principales a través del gradiente batimétrico estudiado: en el talud superior a profundidades alrededor de los 600 m, en el talud medio entre 800 y 1300 m, y en el talud inferior por debajo de los 1300 m. La caracterización geográfica de la estructura de la ictiofauna se observó principalmente en el talud superior y medio. A profundidades comprendidas entre 1000 y 1200 m fue donde se encontraron los mayores valores de biomasa, debido a la presencia de especies más grandes y con mayores requerimientos energéticos como Alepocephalus rostratus, Mora moro y Galeus melastomus. En el talud medio se detectaron diferencias significativas en abundancia, biomasa y peso medio de los peces entre las tres áreas. También se encontraron en las asociaciones de peces diferencias significativas en estos parámetros en el talud superior e inferior. Con el aumento de profundidad se detecta una disminución de la riqueza específica y la diversidad, indicando un empobrecimiento de la magafauna con la profundidad. Sin embargo se observa alta similaridad entre las áreas de estudio y en las máximas profundidades alcanzadas. Las especies dominantes en los fondos más profundos fueron: Bathypterois mediterraneus, Chalinura mediterranea y Coryphaenoides guentheri. En el talud inferior del mar Balear, el tiburón Centroscymnus coelolepis fue también relativamente abundante. Etmopterus spinax en el Iónico oriental y el teleosteo Cataetyx laticeps en las tres áreas de estudio. Los fondos más profundos del Mediterráneo son refugio para una ictiofauna dominada por pequeñas y medianas especies que habitan en en un ambiente escaso de alimento, en el cual solo algunos grandes peces móviles pueden extenderse. Los resultados se discuten en relación a estudios previos llevados a cabo mayoritariamente en el Atlántico y Mediterráneo occidentalThis work was supported by the Directorate General of Fisheries of the European Commission as part of the project DESEAS (Exploratory survey to collect data of the exploited and virgin stocks of deep-sea shrimp A. antennatus, of interest to the CFP - Study Contract nº 2000/39, DGXIV)Peer reviewe

Precision Cosmology: Successes and Challenges

After briefly reviewing the good agreement between large-scale observations and the predictions of the now-standard CDM theory and problems with the MOND alternative, I summarize several of the main areas of possible disagreement between theory and observation: galaxy centers, dark matter substructure, angular momentum, and the sequence of cosmogony, updating earlier reviews [1]. All of these issues are sufficiently complicated that it is not yet clear how serious they are, but there is at least some reason to think that the problems will be resolved through a deeper understanding of the complicated "gastrophysics" of star formation and feedback from supernovae and AGN.Comment: 5 pages, 1 figure, to appear in proceedings of 7th UCLA Symposium on sources and detection of dark matter and dark energy in the universe, 22-24 Feb 2006, Marina de Rey, Californi

Observaciones sobre la distribución, estructura de la población y biología de Bathypterois Mediterraneus Bauchot, 1962 en tres áreas del Mar Mediterráneo

[EN] During the DESEAS cruise Bathypterois mediterraneus specimens were sampled in the Balearic Sea between 1000 and 2800 m as well as in the western and eastern Ionian Sea from 800 to 3300 m and from 800 to 2600 m respectively. The species was found to be more abundant at depths of 1500-2000 m. The size-range was 26-190 mm and the most abundant size class was around 100-120 mm standard length. No significant size-depth trends were shown for either length or weight. Negative allometry was shown in the growth of fishes and otoliths and in the relationship between fish length and otolith size in the samples from the western and eastern Ionian Sea. In these two areas the absolute growth was estimated by adopting the Von Bertalanffy function (western Ionian: SL∞ = 194.3 ± 38.51 mm, k = 0.146 ± 0.061/year, t0 = - 0.921 ± 0.699, f' = 3.74; eastern Ionian: SL∞ = 180.23 ± 63.36 mm, k = 0.150 ± 0.112/year, t0 = - 0.968 ± 0.868, f ' = 3.70). Although most of the specimens were immature, some ripe gonads were recorded in individuals greater than 104 mm in standard length, confirming the simultaneous hermaphroditism in this fish. The results are discussed in relation to previous observations on the life strategy of B.mediterraneus in the Mediterranean Sea[ES] Durante la campaña DESEAS se obtuvieron especímenes de Bathypterois mediterraneus en el mar Balear entre 1000 y 2800 m así como en el mar Iónico occidental y oriental entre 800 y 3300 y entre 800 y 2600 m, respectivamente. La mayor abundancia de esta especie se encontró a profundidades comprendidas entre 1500 y 2000 m. El rango de tallas encontrado abarcó entre 26 y 190 mm y la clase de talla de mayor abundancia fue 100 - 120 mm de longitud estandar. No se encontraron tendencias significativas que relacionaran la talla o el peso con la profundidad. Se encontró alometría negativa en el crecimiento de los ejemplares, en los otolitos y en la relación entre la longitud del pez y la talla del otolito en las muestras del mar Iónico. En estas dos áreas del Iónico, el crecimiento absoluto se estimó por medio de la función de von Bertalanffy (Iónico occidental: SL∞ = 194.3 ± 38.51 mm, k = 0.146 ± 0.061/año, t0 = -0.921 ± 0.699, φ’ 0 3.74; Iónico oriental, SL∞ = 180.23 ± 63.36 mm, k = 0.150 ± 0.112/año, t0 = - 0.968 ± 0.868, φ’ = 3.70). A pesar de que la mayoría de especimenes fueron inmaduros, se registraron algunas gónadas ovadas en individuos superiores a 104 mm de longitud estandar, confirmando el hermafroditismo simultáneo en esta especie. Los resultados se discuten en función de observaciones previas realizadas sobre la estrategia vital de B. mediterraneus en el mar MediterráneoThis work was supported by the Directorate General of Fisheries of the European Commission as part of the DESEAS project (Exploratory survey to collect data of the exploited and virgin stocks of deep-sea shrimp A. antennatus, of interest to the CFP)Peer reviewe

Materiali didattici su diritto del lavoro e digitalizzazione

I capitoli del volume ruotano attorno al nucleo tematico degli effetti delle nuove tecnologie e della digitalizzazione dell'economia sui principali istituti del diritto del lavoro, attraverso l'approfondimento delle questioni più rilevanti: dal lavoro tramite piattaforme digitali al lavoro a distanza, dai controlli informatici alla tutela dei dati personali, dall'obbligo di riservatezza connesso al whisteblowing all'impatto dell'intelligenza artificiale; dalle tutele sociali del lavoratore digitale al software come opera intellettuale del lavoratore, sino al ruolo dell'autonomia collettiv

Loligo forbesi and Ommastrephid squids by-catches on the north-eastern Ionian Slope: preliminary analysis of stock structure based on exploratory trawling

Four trawl surveys were carried out on the slope of the North-eastern Ionian Sea, from September 1999 to September 2000, in the framework of the project “Interregional environmental studies in the Ionian Sea (INTERREG II)”. The bottom area investigated was subdivided into four depth strata: 300-500, 500-700, 700-900 and 900-1200 m; and the sampling was based on random-stratified design. Between the cephalopod species collected during exploratory trawling, Loligo forbesi and Ommastrephid squids were those with the greatest commercial potential. A first analysis of the resource is presented here. Stratified CPUE indices showed that Loligo forbesi, Todarodes sagittatus, Todaropsis eblanae and Illex coindetii constituted the major part (>70%) of cephalopod catches between 300 and 700 m during autumn and spring, but was quite lower in summer due to the scarcity of ommastrephids in the catches. L. forbesi was constantly present in the stratum 300-500 m throughout the year, dominated by immature individuals. Among the two short-fined squids, the proportion of I. coindetii was higher in both autumns whereas T. eblanae was more abundant in spring. Their low catches in July are probably related with the high post-spawning mortality of these species. No seasonal trend could be defined in the catches of the pelagic T. sagittatus. The occurrence of fully mature males in the study area, indicates probable spawning locations of the species

Especies de condrictios en aguas profundas del mar Mediterráneo

[EN] Data collected during the DESEAS survey carried out in three areas of the Mediterranean Sea (Balearic Sea, western and eastern Ionian Sea) were used to describe the distribution and abundance of chondrichthyes species at depths between 600 and 4000 m. A total of 8 chondrichthyes species were recorded, 5 of them in the Balearic Sea, 4 in the western Ionian and 6 in the eastern Ionian. A decrease in abundance with depth was observed in each species with the exception of Centroscymnuscoelolepis. The most abundant species were Galeus melastomus and Etmopterusspinax. The depth range of some species was updated. G. melastomus was caught down to 1500 m, exhibiting a smaller-deeper pattern in females, while E.spinax was captured down to 2200 m with a bigger-deeper trend. Mature females of these two sharks were found between 600 and 1500 m. A wide size-range was shown in both species. C.coelolepis was only collected in the Balearic Sea down to 2800 m. The presence of a pregnant female was sampled from a depth of 1500 m. The distribution of the species is discussed in the context of the present knowledge of the Mediterranean ichthyofauna[ES] Para describir la distribución y abundancia de las especies de condrictios a profundidades entre 600 y 4000 m, se utilizaron muestras de la campaña DESEAS en tres áreas del Mediterráneo (mar Balear y Iónico oriental y occidental). Se registraron un total de 8 especies de condrictios de las cuales 5 de ellas corresponden al mar Balear, 4 al Iónico occidental y 6 al Iónico oriental. En cada una de las especies se observaó un descenso de abundancia con la profundidad a excepción de Centroscymnus coelolepis. Las especies más abundantes fueron Galeus melastomus y Etmopterus spinax. Se amplió el rango de distribución de algunas especies, G. melastomus fue capturado por debajo de 1500 m y las hembras redujeron su talla con la profundidad (smaller-deeper pattern), mientras que E. spinax que se capturó hasta 2200 m presentó una tendencia a aumentar su tamaño con la profundidad (bigger-deeper trend). Entre 600 y 1500 m se encontraron hembras maduras de estas dos especies. También ambas especies presentaron un amplio rango de tallas. C. coelolepis solo se encontró en el mar Balear a 2800 m de profundidad. De esta especie se encontró una hembra ovada a 1500 m. Finalmente se discute la distribución de estas especies en el marco de los conocimientos actuales de la ictiofauna mediterráneaThis work was supported by the Directorate General of Fisheries of the European Commission as part of the DESEAS project (Exploratory survey to collect data of the exploited and virgin stocks of deepsea shrimp A. antennatus, of interest to the CFP Study contract 2000/39, D.G. XIV)Peer reviewe

Nuevas citas de peces teleósteos de aguas profundas en los mares Balear e iónico (Mar Mediterráneo)

[EN] During an EC-funded research carried out in the Mediterranean Sea deep-water fish (600-4000 m) were collected in the Balearic Sea as well as the western and eastern Ionian Sea. Caelorhynchusmediterraneus is a new record for the Balearic Sea, Cyclothone braueri, Hygophum benoiti, Paralepis speciosa, Chalinura mediterranea, Coryphaenoides guentheri, C. mediterraneus, Lepidion lepidion and Cataetyx laticeps for the western Ionian Sea, and Polyacanthonotus rissoanus, C. guentheri, C. mediterraneus, L. lepidion and C. laticeps for the eastern Ionian Sea. The bathymetric distribution of other species has been updated. Species richness decreased with depth in the three surveyed areas, showing a significant shift below 1500 m. At depths greater than 1000 m macrourid and morid species were dominant except in the Balearic Sea, where Alepocephalus rostratus was found to be very abundant as deep as 1500 m. At depths greater than 1500 m the dominant species were Bathypterois mediterraneus, C. mediterranea and C. guentheri. The results of this research confirm the scarcity of deep fish fauna in the Mediterranean compared to the Atlantic. For the greatest depths are concerned, the faunistic difference between the western and eastern Mediterranean seems to be most probably due to a lesser number of investigations on the eastern side rather than any real paucity of ichthyofauna[ES] Se recolectaron especies de peces en el mar Balear y en el Iónico oriental y occidental, gracias a una investigación subvencionada por la CE en aguas profundas del Mediterráneo (600-4000 m). Caelorhynchus mediterraneus es una nueva cita para el mar Balear, Cyclothone braueri, Hygophum benoiti, Paralepis speciosa, Chalinura mediterranea, Coryphaenoides guentheri, C. mediterraneus, Lepidion lepidion y Cataetyx laticeps lo son para el mar Iónico occidental, Polyacanthonotus rissoanus, C. guentheri, C. mediterraneus, L. lepidion y C. laticeps para el mar Iónico oriental. También se ha puesto al día la distribución batimétrica de otras especies. En las tres áreas muestreadas se ha observado que la riqueza específica desciende con la profundidad, marcándose un cambio significativo por debajo de los 1500 m. A profundidades superiores a 1000 m las especies de macrúridos y móridos fueron dominantes excepto para el mar Balear donde Alepocephalus rostratus fue la especie más abundante hasta 1500 m. A profundidades superiores a los 1500 m las especies dominantes fueron Bathypterois mediterraneus, C. mediterranea y C. guentheri. Los resultados confirman la escasez de ictiofauna profunda en el Mediterráneo comparada con la del Atlántico. Hasta las máximas profundidades muestradas, la diferencia faunística entre el Mediterráneo occidental y oriental parece ser debida, más al menor número de investigaciones llevados a cabo en el Mediterráneo oriental, que no a unas determinadas pautas en la distribución y abundancia dicha ictiofaunaThis work was supported by the Directorate General of Fisheries of the European Commission as part of the project DESEAS (Exploratory survey to collect data of the exploited and virgin stocks of deep-sea shrimp A. antennatus, of interest to the CFP - Study contract nº 2000/39, DGXIV). The authors wish to thank V. Catalano for providing helpful literaturePeer reviewe