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Special issueThe wrapping up of the IDEADOS project: International Workshop on Environment, Ecosystems and Demersal Resources, and Fisheries.-- 11 pages, 5 figures, 5 tables, The pelagic decapod crustacean fauna of two different zones (Sóller and Cabrera) with different hydrographic dynamics and oligotrophy levels was studied around Mallorca (western Mediterranean), the latter with a higher degree of oligotrophy than the former. Samples were taken with a Pelagic Trawl and an IKMT in the upper 600. m of the water column, targeting larger and middle-sized nektonic species, respectively. Fourteen species were collected: five dendrobranchiate shrimps, eight caridean shrimps and one scyllarid lobster. Some species were restricted to the shelf-break: Chlorotocus crassicornis and Plesionika heterocarpus. Others were exclusive of the middle slope: Pasiphaea multidentata, and Sergia robusta. Pasiphaea sivado and Gennadas elegans occurred in all pelagic strata. Multivariate analyses showed several distinct assemblages related to bathymetry and sampling depth. No significant differences were found concerning zone or sampled seasons. Bathymetrically, Deep Scattering Layers showed the highest diversity. No decapod crustaceans occurred in epipelagic daytime samples. The pelagic decapod community sampled was structured by both the geomorphology (and associated hydrographic characteristics over the shelf-break) and the influence of light in the water column. Size analysis showed species-specific patterns concerning size/age movements into the water column throughout the day-night cycle. © 2013 Elsevier B.V., Funding was provided by research projects CTM2008-04489-C03 and CTM2010-22218-C02. DSS acknowledges the pre-doctoral fellowship support by the Spanish Agency for International Development Cooperation (AECID), Ministry of Foreign Affairs and Cooperation. APT acknowledges pre-doctoral FPI Fellowship support from the Regional Government of the Balearic Islands, Conselleria d'Educació, Cultura i Universitats, selected as part of an operational program cofinanced by the Fondo Social Europeo. DSS and PA acknowledge partial support from research project CTM2010-22218-C02

Special issue Technological Oceanography.-- 10 pages, 6 figures, 1 table.-- Data Availability Statement: No new data were created or analyzed in this study. Data sharing is not applicable to this article, Different types and systems to discriminate plankton samples at different strata in the water column have been developed in recent decades. For sampling at sufficient depth, opening and closing zooplankton multinets are ideal because there is no contamination of one sample with organisms of the previous one. However, for bigger nets, such as those used to collect micronektonic organism, it is difficult to use multiple net units, and multiple cod ends are preferred because of their simplicity, but with the problem of sample contamination from having a common net passageway. We present here a cod-end Multisampler design, VERDA, that uses a carrousel-like system. Similar to some sediment traps, the system works like a revolver with six or eight compartments whose turning mechanism is triggered when the net arrives to a programmed depth level. This prototype was built with inexpensive and recycled components and electronics similar to Arduino® and Teensy PCB to carry out electronic control. The net we used for testing the equipment was a mid-size midwater trawl of ca. 30 m2 and total length of 58 m that works with a single towing cable and no doors. The overall system is useful for all type of ships, due to the relatively easy deployment operations and because the Multisampler does not need electrical cable or acoustics. In our case, we used a Marport® (Reykjavik Iceland) and Scanmar (Åsgårdstrand, Norway) sensors for real-time depth monitoring and opening distance, This research was funded by the projects “Migrants and Active Flux in the Atlantic Ocean” (MAFIA, CTM2012-39587-C04) and “Biomass and Active Flux in the Bathypelagic Zone” (Bathypelagic, CTM2016-78853-R) from the Spanish Ministry of Economy and Competitiveness, and SUMMER (grant agreement number 817806) from the European Union (Horizon 2020 Research and Innovation Programme), and the support through the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S)

15 pages, 11 figures, 2 tables, supplementary data https://doi.org/10.1016/j.dsr2.2022.105111, This study examines vertical distribution of the early stages of mesopelagic fishes in the south-eastern Indian Ocean and oceanographic factors that may affect it. This investigation along the 110 °E transect formed part of the second International Indian Ocean Expedition (IIOE-2). Depth-stratified samples to 500 m depth of early stages of mesopelagic fishes were obtained by means a multinet EZ-1 m2. This net captured larvae and transforming stages, but juveniles and adults were also caught, particularly at night. Diel vertical patterns of the different species and stages were analysed relative to the oceanographic conditions encountered at the 20 stations along the transect. This paper provides the ranges of vertical occurrence and weighted mean depth for larvae (135 taxa), and post-metamorphic stages (75 taxa) of fishes caught during the survey. Despite the varying vertical profiles of oceanographic parameters encountered, there were consistent patterns within species and families along the transect, with broader vertical distribution of larvae at the southern stations, where the upper mixed layer was deeper. During both day and night, larval stages of all the species were concentrated in the epipelagic zone, with some differences in terms of weighted mean depth (WMD) between taxa, but with no significant differences in vertical location between day and night. Transforming and juvenile-adult stages, however, presented a wider vertical distribution range than larval stages, and showed important differences among families and species. For example, Myctophidae and Phosichthyidae species presented the highest concentrations in the upper 50–100 m at night, and a much deeper distribution during the day, thereby indicating night vertical migration behaviour of transforming and juvenile-adult stages. By contrast, during these stages the Gonostomatidae Cyclothone spp. and the Sternoptychidae Argyropelecus spp. occurred deeper than the epipelagic layer during both day and night. Although these vertical patterns concur with results from other oceans, the WMD along 110 °E was slightly deeper than that observed in other areas, such as the eastern Atlantic, possibly related to water transparency in this oligotrophic part of the world's oceans, MPO acknowledges the support of her institution through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) and travel funding from Murdoch University

13 pages, 7 figures, 3 tables, As part of the second International Indian Ocean Expedition, an oceanic transect from 39.5°S to 11.5°S along 110°E in the south-eastern Indian Ocean enabled concurrent oceanographic measurements and sampling of early stages of mesopelagic fishes within the upper 500 m of the water column. Notable oceanographic features along the generally oligotrophic transect included an increase in surface water temperature from 12 to 28 °C from south to north and low salinities at both ends of the transect. High salinity Subtropical Surface Water was evident over the central part of the transect and low dissolved oxygen occurred at depth at the northern end where tropical waters were influenced by the Indonesian Throughflow. Throughout the study region larval fish stages were generally concentrated in the epipelagic zone. Species richness, abundance and diversity of fishes (n = 166 species) increased towards the tropical waters. The families Myctophidae (lanternfishes; 60 species), Phosichthyidae (lightfishes; 2 species) and Gonostomatidae (bristlemouths; 5 species) were numerically dominant. Clustering of integrated abundance data (0–500 m depth) revealed four major fish assemblages along the transect. When linked to oceanographic variables, multivariate multiple regression indicated that surface temperature, surface salinity and dissolved oxygen at 400 m depth provided the best fitting model explaining fish distribution patterns. Where possible, comparisons have been made with early data collected along this 110° E line in the 1960s during the first International Indian Ocean Expedition, MPO acknowledges the support of her institution through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

The organic carbon resulting from photosynthesis in the upper ocean is transferred downward through the passive sinking of organic particles, physical mixing of particulate and dissolved organic carbon as well as active flux transported by zooplanktonic and micronektonic migrants. Several meso- and bathypelagic organisms feed in shallower layers during the nighttime and respire, defecate, excrete and die at depth. Recent studies suggest that migrant micronekton transport similar amounts of carbon to migrant zooplankton. However, there is scarce information about biomass and carbon flux by non-migratory species in the mesopelagic and bathypelagic zones. The non-migratory bristlemouth fishes (Cyclothone spp.) and partial migrator (A. hemigymnus) remineralise organic carbon at depth, and knowledge about this process by this fauna is lacking despite them having been referred to as the most abundant vertebrates on Earth. Here we show the vertical distribution of biomass and respiration of non-migratory mesopelagic fishes, during day and night, using the enzymatic activity of the electron transfer system (ETS) as a proxy for respiration rates. The study is focused on five Cyclothone species (C. braueri, C. pseudopallida, C. pallida, C. livida and C. microdon) and Argyropelecus hemigymnus. The samples were taken on a transect from the oceanic upwelling off Northwest Africa (20° N, 20° W) to the south of Iceland (60° N, 20° W). Cyclothone spp. showed, by far, the largest biomass (126.90 ± 86.20 mg C·m⁻²) compared to A. hemigymnus (0.54 ± 0.44 mg C·m⁻²). The highest concentrations of Cyclothone spp. in the water column were observed between 400 and 600 m and from 1000 to 1500 m depths, both during day and night. For the different species analysed, ETS activity did not show significant differences between diurnal and nocturnal periods. The total average specific respiration of Cyclothone spp. (0.02 ± 0.01 d⁻¹) was lower than that observed for A. hemigymnus (0.05±0.02 d⁻¹). The average carbon respiration of Cyclothone spp. was 2.22 ± 0.81 mg C·m⁻²·d⁻¹, while it was much lower for A. hemigymnus (0.04 ± 0.03 mg C·m⁻²·d⁻¹). The respiration of Cyclothone spp. was lower in the bathypelagic than in the mesopelagic zone (0.84 ± 0.48 vs 1.36 ± 1.01 mg C·m⁻²·d⁻¹, respectively). These results, to our knowledge, provide the first account of remineralisation by this community in the meso and bathypelagic zones of the ocean., Biomass and Active Flux in the Bathypelagic Zone, BATHYPELAGIC, MESOPELAGICOS, SI

14 pages, 7 figures, 3 tables, supplementary data https://doi.org/10.1016/j.pocean.2022.102894.-- Data availability: The data that has been used is confidential, The biological carbon pump is the process that transports carbon vertically out of the mixed layer in the ocean. Besides the sinking flux of organic particles, active flux due to the daily vertical migration of zooplankton and micronekton promotes a significant carbon transport not fully accounted for or understood in the world’s oceans. The diversity and abundance of epipelagic and mesopelagic species in the Gulf of California has been extensively studied, but the role of micronekton in carbon export has not yet been investigated. We studied the carbon flux promoted by juvenile and adult mesopelagic fishes and crustaceans (Decapoda and Euphausiidae) during the transition from the cold to warm period (June) and the onset of the warm season (October) in 2018. We provide the first estimation of migrant biomass and respiratory flux of the most abundant migratory species of mesopelagic fishes, decapods and euphausiids in the Gulf of California. The micronekton species collected accounted for a large biomass of mesopelagic fishes and pelagic crustaceans. The average migrant biomass estimates were 151.5 ± 101.2 mg C·m−2 during June and 90.9 ± 75.3 mg C·m−2 during October. The enzymatic activity of the electron transfer system (ETS) was measured as an estimate of their respiratory rates. Average specific ETS activity was significantly different between fishes and decapods, and between fishes and euphausiids (p, Universidad Nacional Autónoma de México supported the use of the R/V El Puma during these two oceanographic cruises carried out in the Gulf of California during 2018. Additional funding for this research came from Centro Interdisciplinario de Ciencias Marinas-Instituto Politécnico Nacional, Mexico (SIP 20180084), Instituto de Ciencias del Mar y Limnología from the Universidad Nacional Autónoma de México, Mexico (PAPIIT-UNAM IN210622, IN200610-3, IN218106, IN202319, Mexico), Consejo Nacional de Ciencia y Tecnología, Mexico (CONACYT Ciencia Básica 2016-C01- 284201), and by the European Union (Horizon 2020 Research and Innovation Programme) through projects SUMMER (Grant Agreement 817806), TRIATLAS (Grant Agreement 817578) and the Spanish Government through the Project Desafío (PID2020-118118RB-I00). J.G.G. and C.J.R. are SNI fellows and J.G.G. also is EDI-IPN and COFAA-IPN fellow. A.S. was supported by a postgraduate grant from the Spanish Ministry of Science and Innovation (BES-2017-082540), With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

9 pages, 3 figures, 1 table, supplementary data https://doi.org/10.1093/icesjms/fsab189.-- Data availability statement: The original data on sample location, individual fish characteristics and stable isotope composition, including amino acids, can be accessed through the PANGAEA repository (Bode et al., 2021b). Similarly, the original data for copepods can be found in Bode et al. (2018b), The trophic position (TP) of fishes determines their importance in terms of energy flows within food webs. However, accurate estimations of TP are often prevented because of the difficulties in tracing all food sources. This is particularly challenging for omnivorous fishes, such as those from the Order Stomiiformes. In this study, we applied recent developments in stable isotope analysis of amino acids to untangle the contributions of microbial vs. metazoan food webs in 13 species of Stomiiformes. The inclusion of the microbial food web reduced the differences between TP estimates using stable isotopes and those derived from stomach content analysis. In addition, the new estimates allowed to quantify the relative contribution of the microbial food web to each species (6–21%), highlighting the importance of detritus consumption even in piscivorous species (e.g. Stomias boa and Chauliodus danae). The comparison of TP estimates obtained with selected amino acids in fish muscle allowed for the detection of the microbial influence integrated at time scales relevant for net fish growth, even when trophic exchanges in the microbial food web occur at much shorter time scales. The assessment of TP considering the differential contribution of microbial and metazoan food webs challenges our current understanding of marine food webs; yet provides a new quantitative tool for the analysis of their structure and function, This research was funded by projects MAFIA (CTM2012-39587-C04), BATHYPELAGIC (CTM2016-78853-R), and QLOCKS (PID2020-115620RB-100) from the Plan Estatal de I+D+I (Spain), projects SUMMER (grant agreement number 817806) and TRIATLAS (grant agreement number 817578), from the European Union (Horizon 2020 Research and Innovation Programme), and the support through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

17 pages, 9 figures, 4 tables, supplementary material https://doi.org/10.3354/meps13748, We assessed the trophic ecology of blue whiting larvae in the NW Mediterranean by means of stomach content analyses in relation to their planktonic trophic environment. The trophic position of blue whiting larvae and that of the main taxa of the planktonic community was estimated by means of stable isotope analyses. Larvae and zooplankton were sampled in 2 oceanographic cruises conducted in the winters of 2017 and 2018. Blue whiting larvae showed a marked diel feeding pattern and high feeding incidence (~90%). Throughout ontogeny, dietary changes were observed in the taxonomic composition, size and number of ingested prey. The smallest larvae fed on small prey, Tintinnina and nauplii, shifting to larger more energetic prey, Calanoida copepods, as development progressed. From the flexion stage onwards, larvae showed a positive selection for Calanoida, and no major switch in prey size or type was observed due to the scarcity of larger prey in the field. This limitation forced the larger larvae to increase the number of ingested prey (reaching >300 prey larva-1) to meet their energetic demands. In line with the observed shifts in diet, larvae showed an increase in δ13C and δ15N values throughout development. The trophic position estimates of the planktonic taxa shed light on the trophic structure of the planktonic community, identifying blue whiting larvae as a primary carnivore. Overall, the results suggest that blue whiting larvae feed efficiently in the Mediterranean trophic environment, This research was funded by project CTM2015-68543-R. J.M.-A.was supported by a predoctoral fellowship of the FI program of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya, Spain, and Fons Social Europeu (FSE) [2019FI_B2 00183]. J.N. was funded by the Spanish National Program Ramón y Cajal (RYC-2015-17809), Ministry of Science and Innovation, Spain. [...] This work acknowledges the Severo Ochoa Centre of Excellence accreditation (CEX2019-000928-S)

10 pages, 6 figures, 5 tables, supplementary material https://doi.org/10.3989/scimar.05106.007, [EN] The age and growth patterns of the mesopelagic fish Ceratoscopelus maderensis (family Myctophidae) of the western Mediterranean Sea were described throughout its entire life cycle (from larvae to adult stages) using the sagittae otoliths of 59 individuals collected in December 2009. Three characteristic zones were identified along the cross-section of the sagittae (larval, metamorphic and juvenile-adult zones). Assuming growth rings as daily increments, the age of the analysed individuals (from 3.5 to 64 mm standard length [SL]) would range from 7 to 332 days. The relationship between the number of increments and the fish SL was fitted to a von Bertalanffy growth model (SL=70.5899×(1–exp(–0.0501(t+2.6705))). The growth pattern of C. maderensis in the western Mediterranean Sea was similar to that reported for this species in the northeast Atlantic Ocean. Though from a body size of 40-45 mm SL, growth rates declined more slowly in individuals from the western Mediterranean Sea, growth differences between these individuals and those from the northeast Atlantic Ocean were not statistically significant. This study provides new insights into the age and growth patterns of one of the most abundant mesopelagic fish species in the Mediterranean Sea that have clear implications for the study and management of marine ecosystems, [ES] En el presente trabajo se describen la edad y los patrones de crecimiento desde la fase larvaria hasta la fase adulta del pez mesopelágico Ceratoscopelus maderensis (familia Myctophidae) del Mediterráneo occidental. Para ello, se analizó el otolito sagitta de 59 individuos capturados en diciembre de 2009. Se identificaron tres zonas en la sagitta, cada una de las cuales se corresponde con una fase del desarrollo ontogenético del pez: larvaria, metamórfica y juvenil-adulta. Asumiendo que los anillos de crecimiento son diarios, la edad de los individuos analizados (de 3.5 a 64 mm de longitud estándar [SL]) oscilaría entre 7 y 332 días. La relación entre el número de incrementos y la SL de los peces se ajustó al modelo de crecimiento de von Bertalanffy (SL=70.5899×(1–exp(–0.0501(t+2.6705))). El patrón de crecimiento de C. maderensisen el Mediterráneo occidental fue similar al previamente descrito para esta especie en el Noreste del Océano Atlántico. A pesar de que, a partir de 40-45 mm SL, las tasas de crecimiento disminuyeron más lentamente en los individuos del Medi-terráneo occidental, las diferencias de crecimiento entre estos individuos y los del Noreste del Océano Atlántico no fueron estadísticamente significativas. Los resultados de este estudio aportan nuevos conocimientos sobre la edad y el crecimiento de una de las especies más abundantes del Mar Mediterráneo, lo cual tiene claras implicaciones de cara al estudio y la gestión de los ecosistemas marinos, The authors are very grateful to the IDEADOS project (CTM2008-04489-C03-02) and for the technical sup-port offered by José Manuel Fortuño (ICM) and Silvia Pérez-Mayol of the Sclerochronology Service at IME-DEA (UIB-CSIC), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

11 pages, 2 figures, 4 tables, supporting information https://doi.org/10.1111/jfb.14307, Length–weight relationships (LWRs) were estimated for 36 mesopelagic fish species collected from the equatorial and tropical Atlantic encompassing several oceanographic regions: oligotrophic, equatorial, Cape Blanc, Cape Verde and the Canary Islands. The sample was composed of myctophids (25 species), gonostomatids (5), sternoptychids (3), stomiids (2) and phosichthyids (1). The species were clustered according to body shape: “short‐deep” (sternoptychids), “elongate” (gonostomatids, stomiids and some phosichthyids) and “fusiform” (myctophids and some phosichthyids). Three types of weight and LWRs were considered: wet weight (WW ), eviscerated wet weight (eWW ) and eviscerated dry weight (eDW ). The study demonstrated that most species present a positive allometric growth, independent of the weight used. However, the allometric value varied in 40–50% of species depending on the type of weight considered. Significant variations linked to fish morphology were found in the relationship between the slope and intercept of the LWR equation. Significant differences were also noted in the water content linked to fish body shape. Based on the distributions of several species we compare their fitness between oceanographic regions using the relative condition factor (K rel). Except for Diaphus brachycephalus (oligotrophic vs. equatorial waters) and Lampanyctus alatus (equatorial, Cape Blanc, Cape Verde and the Canary Islands), no regional significant differences were observed in the species analysed, This research was sponsored by the Spanish Ministerio de Economía y Competitividad through the project CTM2012-39587-C04-03, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Special issue: The Second International Indian Ocean Expedition (IIOE-2): Motivating New Exploration in a Poorly Understood Ocean Basin Volume 3).-- 14 pages, 7 figures, 3 tables, supplementary data https://doi.org/10.1016/j.dsr2.2020.104841, Mesopelagic fishes of the southeastern Indian Ocean are represented by a high number of lanternfish species (Myctophidae). The horizontal distribution patterns of their larvae have been previously studied; however, research on larval feeding habits is non-existent. The goal of this study was to describe the diet and trophic-based strategies of the most abundant myctophid larvae off Western Australia through stomach content analysis. Samples were collected in autumn 2007 off southwestern Australia when this oligotrophic area was under the influence of the seasonal Leeuwin Current, and in autumn 2010 on the tropical continental shelf of northwestern Australia. The species investigated during these periods were Benthosema fibulatum, B. pterotum, B. suborbitale, Dasyscopelus asper, Diaphus “deep” and “slender” morphotypes, Hygophum hygomii, Lampadena luminosa, Lampanyctus alatus, Lampanyctus spp. and Myctophum sp. Generally, myctophid larvae showed a diurnal feeding pattern. Only postflexion stages in L. alatus, L. luminosa, B. pterotum, Diaphus “slender”, and Myctophum sp. preyed at dawn or during the night. The highest feeding incidence was found in L. luminosa and the Diaphus “deep” morphotype, while the lowest, in H. hygomii. Generally, larvae were zooplankton feeders with nauplii and copepodites being the most abundant dietary groups, except for B. suborbitale and Myctophum sp. where the small non-calanoid genus Oncaea was dominant. Soft organisms such as appendicularians were frequent items in most fish diets throughout their entire larval phase, and highly abundant in Diaphus “deep” morphotype. The wide prey-size spectrum indicates that the majority of the fish species were not size-specific feeders for most of their larval life. Nevertheless, B. suborbitale, B. fibulatum, and L. alatus preferred larger prey, ignoring the smaller items as they grew. Larval feeding patterns of similar genera from other ecosystems are discussed and compared with those in Western Australia, Ainhoa Bernal was the recipient of a PhD scholarship associated with the project CTM 2008-04489-C03-02 awarded by the Spanish Ministry of Science and Innovation, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

13 pages, 7 figures, 3 tables, supplementary data https://dx.doi.org/10.1093/icesjms/fsx243, Lanternfishes (Myctophidae) constitute the most important component of the daily vertically migrating mesopelagic fish community. This research addresses the estimation of the trophic position and diet of myctophids using stable isotope analyses. Fishes were collected across the central Atlantic, from a very productive zone influenced by the Mauritanian upwelling to the western oligotrophic equatorial waters. The survey also encompassed a zone of low oxygen concentration in the mesopelagic layers. Determinations of δ13C and δ15N values were made on the 20 most frequent and abundant myctophids, from small-sized species (e.g. Notolychnus valdivae) to larger ones (e.g. Myctophum punctatum). Isotope analyses on the seston and several plankton groups were also performed to assess the influence of zonal differences in trophic position (TP) calculations, and to use as food sources in diet estimations. Myctophids displayed a narrow range of trophic positions, being greater than 2 and less than 4, except for N. valdiviae (TP = 1.7). Comparisons of diets estimated through an isotopic mixing model differentiated the smallest species, with a strong seston signature (Diogenichthys atlanticus and N. valdiviae), from the Diaphus species of medium sizes, (D. brachycephalus, D. holti, and D. rafinesquii), which feed on prey of higher TP values, This research has been funded by the Spanish Ministerio de Economía y Competitividad through projects CTM2012-39587-C04 and CTM2016-78853-R

17 pages, 4 figures, 9 tables, supplementary material http://dx.doi.org/10.1016/j.pocean.2015.03.005, Myctophids, gonostomatids and sternoptychids are the most abundant teleosteans worldwide and constitute an important assemblage of the mesopelagic ecosystem, functioning as vehicles of energy and matter through trophic webs. This study concentrates on the trophic ecology of the most abundant mesopelagic fishes of the western Mediterranean (WM) based on stomach content analysis. The myctophids (in this study: Benthosema glaciale, Ceratoscopelus maderensis, Lobianchia dofleini, Myctophum punctatum, Hygophum benoiti, Hygophum hygomii, Lampanyctus crocodilus, Lampanyctus pusillus and Notoscopelus elongatus) perform extensive diel migrations across the water column, between the surface to as deep as 1000. m, interacting with plankton and micronekton at multiple depths, and generally feeding in the epipelagic layers at night. In contrast, the gonostomatids Cyclothone braueri, Cyclothone pygmaea, and the sternoptychid Argyropelecus hemigymnus remain below epipelagic layers, feeding at different times throughout the day and night. The diet composition, trophic niche breadth and prey selectivity of 11 of these fish species were determined for juvenile and adult individuals from two surveys performed in December 2009 and July 2010 in the western Mediterranean Sea. The number of prey items varied among species, e.g. Myctophum punctatum was the species with the highest feeding intensity, reaching ca. 700 prey items in a stomach, whereas the mean number of prey in Cyclothone braueri was low (usually 1 or 2 prey per stomach). A dietary shift towards larger prey was evident from juveniles to the largest and oldest adult individuals, despite trophic niche breadths did not increase with body length for any of these mesopelagic species. The diets of the small gonostomatids, sternoptychid and early juveniles of myctophids were dominated by non-calanoid copepods, ostracods, and other small zooplankton, whereas medium-sized myctophids, e.g. L. dofleini or H. benoiti, preyed mainly on calanoids. The oldest stages of L. crocodilus and N. elongatus fed mostly on macrozooplankton and micronekton. There was high diet overlap among mesopelagic fish species and strong heterogeneity in diet composition at intraspecific level. Nevertheless, some species showed certain degree of segregation of food resources, determined by the developmental stage or spatial distribution, and positive selection towards particular prey items. The Chesson's electivity index showed that L. dofleini, N. elongatus, L. crocodilus and L. pusillus preyed selectively on euphausiids; B. glaciale was selective on the calanoid genus Pleuromamma, and C. maderensis preferred to feed on larvaceans in autumn. The two congeneric species of Hygophum consumed a high number of food items, but H. hygomii showed positive selection for euphausiids, whilst H. benoiti preferred small corycaeid copepods. Overall, the main trophic difference among mesopelagic fishes in the WM was observed between the small non-migratory species that do not evidence a diel rhythm, feeding during both day- and night-time on small zooplankton, and the largest-sized myctophids, which fed on meso- and macrozooplankton and, more occasionally, on small fishes. Mediterranean midwater fishes can be characterised by the adoption of mixed feeding strategies, with varying degrees of specialisation on different prey types that allow flexibility in a changeable environment. © 2015 Elsevier Ltd., This research was funded by the Project CTM2008-04489-C03-02 of the Ministry of Science and Innovation in Spain

Villarino, Ernesto ... et al.-- 13 pages, 5 figures, 5 tables, supplementary material https://dx.doi.org/10.1038/s41467-017-02535-8, Global patterns of planktonic diversity are mainly determined by the dispersal of propagules with ocean currents. However, the role that abundance and body size play in determining spatial patterns of diversity remains unclear. Here we analyse spatial community structure - β-diversity - for several planktonic and nektonic organisms from prokaryotes to small mesopelagic fishes collected during the Malaspina 2010 Expedition. β-diversity was compared to surface ocean transit times derived from a global circulation model, revealing a significant negative relationship that is stronger than environmental differences. Estimated dispersal scales for different groups show a negative correlation with body size, where less abundant large-bodied communities have significantly shorter dispersal scales and larger species spatial turnover rates than more abundant small-bodied plankton. Our results confirm that the dispersal scale of planktonic and micro-nektonic organisms is determined by local abundance, which scales with body size, ultimately setting global spatial patterns of diversity, This research was funded by the project Malaspina 2010 Circumnavigation Expedition (Consolider-Ingenio 2010, CSD2008-00077) and cofounded by the Basque Government (Department Deputy of Agriculture, Fishing and Food Policy). [...] E.V. was supported by a PhD Scholarship granted by the Iñaki Goenaga−Technology Centres Foundation

22 pages, 12 figures, 7 tables, supplementary data https://doi.org/10.1016/j.pocean.2016.12.001, In this investigation we analysed the changes in fish species occurrences and relative abundances across the tropical and equatorial Atlantic, and their vertical distribution patterns in relation to the different environmental scenarios. The study covers a wide region encompassing different water masses, and marked differences in productivity, from an oligotrophic zone close to the Brazilian coast, to a very productive upwelling region close to the Northwest African upwelling. Fishes were collected with a medium-sized midwater trawl (Mesopelagos), complemented by hauls made with a macrozooplankton net (MOCNESS). Species richness in the region was higher than in subtropical, temperate and cold regions. The total number of species and their overall abundance was lower in the stations closer to the Brazilian coast. Abundant species across the entire region were the gonostomatids Cyclothone alba, Cyclothone acclinidens, Cyclothone pallida and Cyclothone pseudopallida, the myctophid Lampanyctus alatus, the sternoptychid Sternoptyx diaphana, and the phosichthyid Vinciguerria nimbaria. The occurrences and abundances of C. parapallida, Lampanyctus nobilis and Lepidophanes guentheri were related to zones where AAIW waters occupied the mesopelagic layers, while other species such as Cyclothone livida and Polyipnus polli increased their abundance when AAIW disappears from their living depths. The presence of Eastern North Atlantic Central Water (ENACW) was associated with the occurrence of several myctophids (Benthosema glaciale, Ceratoscopelus maderensis, Diaphus holti, Diaphus rafinesquii, Hygophum hygomii, Lampanyctus crocodilus, Myctophum punctatum, Symbolophorus veranyi), and the gonostomatid Cyclothone braueri. In spite of the important differences in hydrographic features across the tropical and equatorial Atlantic, all stations showed either the general night migration into the epipelagic layers carried out by myctophids, phosicthyids, and some stomiids, or the presence of the several species of Cyclothone, sternoptychids and melamphaeids that remain in the mesopelagic layers, both day and night. The oxygen minimum zone (OMZ) at mesopelagic depths in the north-eastern sector does not seem to disrupt diel vertical migration. Day-night distributions in our study proved that mesopelagic migratory species are capable of crossing these wide hypoxic layers, and that some species such as Diaphus vanhoeffeni remain in these layers during the day. Other non-migratory fishes (Cyclothone spp. and S. diaphana) proved to be widely tolerant to these low oxygen concentrations, as shown by their high numerical abundances in the OMZ, This research has been funded by the Spanish Ministerio de Economía y Competitividad through project CTM2012-39587-C04-03

9 pages, 5 figures, 5 tables, In marine communities, energy of small planktonic organisms is transferred to their predators through feeding. The energy accumulated as organic substances by the different plankton organisms (Energetic Density content, E) has been analysed in high latitudes and tropical areas, but not in the Mediterranean Sea. In this study, we approach this type of investigation for Mediterranean plankton through measures of total calorimetric content using an oxygen bomb calorimeter. We examined the spatiotemporal variation in the E of microplankton (50–200 μm) and mesozooplankton (200–2000 μm), and two plankton-consumers, sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) larvae. The study was carried out during the winter and summer of 2013 off the Ebro River Delta (NW Mediterranean Sea). Both plankton fractions showed a more coastal distribution and higher biomasses during winter, the period of sardine larvae occurrences, in front of a wider cross-shelf distribution and lower biomasses in summer, when anchovy appeared. E values increased with the size of each plankton component, i.e., microzooplankton < mesozooplankton < fish larvae. A tendency for higher plankton E in the winter period was observed, although being only significant for coastal zone, associated to the more productive waters there. Sardine and anchovy larvae showed an increasing trend in the amount of energy during development, with significantly lower E between early larvae (6–10 mm standard length) and late postflexion stages (16–20 mm standard length). Small larvae of both species departed from a similarly low E content, but in the next two size classes sardine larvae showed higher E values than anchovy, being significantly higher in the 16–20 mm size class. Information on larval feeding patterns and larval growth rates for each species were used to discuss differences in energy allocation strategies, This study forms a contribution to the project ECOTRANS (CTM201126333, Spanish Ministry of Economy and Competiveness, Spain) and to the Master's thesis of Z.B.

18 pages, 13 figures, 2 tables, 1 appendix supplemental material https://dx.doi.org/10.1016/j.dsr.2016.10.003, We explore the associations between larval fish assemblages and oceanographic conditions in the upper ocean (top 200 m) along the African slope, from tropical (15°N) to subtropical (35°N) latitudes, during a period of intense upwelling. In this extensive region, the northward Mauritanian Current and Poleward Undercurrent carry South Atlantic Central Waters (SACW) while the southward Canary Upwelling Current transports North Atlantic Central Waters (NACW). South of Cape Blanc we only find SACW, and north of Cape Blanc there is NACW far offshore and a combination of NACW and SACW nearshore, separated by the Canary Upwelling Front (CUF). The larvae of different myctophid species serve as indicators of the water masses, e.g. S. veranyi and M. punctatum were found in some coastal stations that were dominated by NACW, while the tropical mesopelagic B. argyrogaster, H. macrochir, M. affine and S. kreffti were associated to the SACW. The along-slope offshore convergence of NACW and SACW takes place at the Cape Verde Frontal Zone (CVFZ), representing a region of extensive offshore export for larvae of coastal species, S. pilchardus and E. encrasicolus, far from their nearshore spawning area. The large-scale frontal systems (CVFZ and CUF) and mesoscale eddies contribute to retain larvae within productive waters, influencing both coastal and oceanic species, This research has been funded by the Spanish Ministerio de Ciencia e Innovacion through projects MOC2 (Reference no. CTM2008-06438-C02-01) and VA-DE-RETRO (Reference no. CTM2014-56987-P)

14 pages, 9 figures, 5 tables, Surface waters are an attractive foraging ground for small fish in the open ocean. This study aims to determine the importance of vertically migrating species in the neuston of oceanic waters across the Atlantic, Indian and Pacific Oceans and to ascertain the influence of environmental variables on their distribution patterns. Neustonic fish assemblages were primarily controlled by light. They were dominated by late-larvae and juveniles of Exocoetidae, Hemiramphidae and Scomberesocidae during the day. At night, the vertical migration of mesopelagic species changed the dominance pattern in favour of Myctophidae and Scomberesocidae. The neustonic families’ distribution was primarily related to sea surface temperatures, whereas environmental variables at deeper layers were related to mesopelagic migrating families. Canonical correspondence analysis showed a low but statistically significant contribution of several environmental variables to myctophid species composition (10%), with minimum oxygen concentrations ranking first in variance explanation followed by maximum fluorescence, sea surface temperature and 400-m temperature. Spatial autocorrelation also explained 17% of the variance, indicating the influence of other factors such as historical, demographic and dispersal constraints. The low number of myctophid species in the North Pacific Equatorial Countercurrent appears to be related to the low oxygen concentrations observed in this province, This study was financed by the Spanish Ministry of Economy and Competitiveness (Consolider-Ingenio 2010, CSD2008-00077 and CTM2012–39587-C04–03)

15 pages, 8 figures, 2 tables, The trophic ecology of the lanternfish Lampanyctus pusillus was investigated using individuals captured off the Balearic Islands (39°N, 2°E) (western Mediterranean) in December 2009. Based on gut content analyses, the trophic niche breadth, diet composition and selectivity were determined for the entire life cycle of L. pusillus. The larval stages fed actively near the surface during the day, with a feeding incidence (FI) of approximately 71 %. In contrast, the adults fed at night, both in near-surface depths and in the 400 m deep scattering layer, with a higher FI (83 %). Diet analysis revealed a shift in the prey choice throughout ontogenetic development, from preflexion individuals, which selected nauplii and small oncaeids, to postflexion larvae, which consumed a variety of calanoids, mainly Clausocalanus spp., to the adults, which preyed on large organisms, exhibiting positive selectivity for Pleuromamma spp. and euphausiids. These results show that the vertical distribution of larvae and adults is partly conditioned by their respective feeding habits, with larvae feeding on small zooplankton in the upper layer and adults preferring to consume larger taxa that perform nycthemeral migrations, This research was supported by project CTM2008-04489-C03-01 and 02 from the Ministry of Education in Spain and is part of the PhD thesis of Ainhoa Bernal

12 pages, 6 figures, 4 tables, [EN] In some routine studies of larval condition based on RNA:DNA ratios, heads and/or guts are removed for further age and feeding analysis. Also, during capture larvae are often found with their eyes missing. In this work we analysed tissues effects (muscle, head, eye, gut and the whole larvae) on RNA:DNA ratios from different species (Sardina pilchardus, Engraulis encrasicolus, Atherina presbyter and Paralichthys orbignyanus) in different developmental stages and from different locations. For all species and development phases, it was shown that RNA:DNA ratios in the head were significantly lower than in muscle or gut. The comparison of RNA:DNA ratios of head with or without eyes did not show significant differences. In a comparison of results from muscle from two tail sections, RNA:DNA ratios were higher for the anterior section in Sardina pilchardus and Engraulis encrasicolus larvae. Caution is needed when RNA:DNA ratios are compared with other studies employing different dissection protocols. For the species studied we propose conversion factors to be applied to RNA:DNA ratio data when different body sections are analysed. We discuss the most appropriate tissues for assessing nutritional condition in fish larvae, based on trends in concentrations of nucleic acids and ratios during starvation experiments, [ES] Efecto del tipo de tejido sobre los cocientes ARN:ADN en larvas de peces marinos. – En estudios de condición nutricional larvaria basados en la relación ARN:ADN, las cabezas y/o tubos digestivos suelen diseccionarse para posteriores estudios de edad o alimentación. Además, durante la captura algunas larvas pierden los ojos. En este trabajo analizamos el efecto de diferentes tejidos (músculo, cabeza, ojos y tubo digestivo) sobre la relación ARN:ADN en Sardina pilchardus, Engraulis encrasicolus, Atherina presbyter y Paralichthys orbignyanus, en diferentes estadios de desarrollo y en diversas regiones. En todas las especies la relación ARN:ADN en la cabeza fue significativamente menor que para el músculo o el tubo digestivo. La comparación de la relación ARN:ADN de la cabeza con o sin ojos no mostró diferencias significativas. Al comparar dos secciones de músculo de la cola en Sardina pilchardus y Engraulis encrasicolus se observó mayor ARN:ADN en la parte anterior que en la posterior. Es necesaria precaución cuando se comparan ARN:ADN entre estudios que emplean diferentes protocolos de disección. Proponemos factores de conversión para ser aplicados a las relaciones ARN:ADN cuando se analizan diferentes secciones del cuerpo. Se discute cuales son los tejidos más apropiados para determinar la condición nutricional de larvas de peces, basados en las concentraciones de ácidos nucleicos y sus cocientes obtenidos en experimentos de inanición, This work was partially funded by the Spanish CTM2004-03510-C02-01/MAR Project, the “Centre de Referència de Recerca i Desenvolupament en Aqüicultura (CRA-CIRIT)” of the “Generalitat de Catalunya” and the Portuguese “Fundação para a Ciência e a Tecnologia” that financed the sabbatical grant to Maria Alexandra Chícharo (SFRH/BSAB/745 /2007), financed by Portuguese “Fundação para a Ciência e a Tecnologia” and by the Spanish CTM2004-03510 C02-01/MAR Project. M.V. Díaz acknowledges MAEC-AECI Fellowship support from the Agencia Española de Cooperación Internacional

The ratio of tissue RNA to DNA (R/D) is a widely used index of recent growth and nutritional condition in larval and juvenile fish. To date, however, no standard technique for measuring nucleic acids has been adopted. Because methodological details can affect the estimate of R/D, researchers using different analytical protocols have been unable to compare ratios directly. Here, we report on the results of an international interlaboratory calibration of 4 spectrofluorometric protocols to quantify nucleic acids. Replicate sets of 5 tissue samples and 2 standards (common standards) were supplied to each of 5 researchers for analysis with their own methods and standards. Two approaches were evaluated for mitigating the observed differences in values: 1) the use of common nucleic acid standards and 2) standardizing to a common slope ratio (slope of DNA standard curve/slope of RNA standard curve or m DNA /m RNA ). Adopting common standards slightly reduced the variability among protocols but did not overcome the problem. When tissue R/Ds were standardized based on a common m DNA /m RNA slope ratio, the variance attributed to analytical protocol decreased dramatically from 57.1% to 3.4%. We recommend that the ratio of the slopes of the standard curves be provided to facilitate intercomparability of R/D results among laboratories using different spectrofluorometric methods for the analysis of nucleic acids in fish.

13 pages, 8 figures, 3 tables, Relationships between environmental factors and the growth and condition of pilchard Sardina pilchardus (Walbaum) larvae were studied in November 1998 in the northwestern Mediterranean(NWM). Long-term growth of fish was assessed using otolith analysis and condition was assessed through histological and biochemical (RNA/DNA) indices. These measurements were conducted on larvae belonging to 2 station groups (A and B) previously defined through principal component analysis (PCA) on 7 environmental variables. Correlations between individual condition indices and environmental values at place of capture were also performed. Condition in environmental group A was significantly higher than in group B as assessed by both histological indices and RNA/DNA. Long-term growth, however, did not differ significantly between groups except for the otolith diameter vs. standard length (SL) relationship. The stations conforming to environmental group A were characterised by environmental ranges that would form a favorable habitat for larval success, including surface temperatures 4500 nauplii(N) m-3 or >5500 of other microzooplankters (T-N) m–3. Apart from the good agreement found between histological and RNA/DNA results, each approach offered different information: histological indices detected the largest portion of unfit larvae at size-ranges ≤8 mm, whereas RNA/DNA best discriminated large larvae. The results from this study support the view that links exist between mesoscale anomalies, spawning intensity and growth or condition of pilchard larvae in the NWM., This research was complied in accordance with all the Spanish laws and was funded by the Spanish research project CYTMAR 97-0902.

14 pages, 7 figures, 2 tables, [EN] Extraction procedures for RNA and DNA in crude extracts of natural microplankton samples are developed. The methodology is compatible with the fluorometric assay of RNA and DNA developed by Berdalet et al. (2005). Mechanical cell disruption using a manual tissue grinder is combined with chemical extraction using 0.5% sarcosine and 0.5 mM EDTA in 5 mM Tris, pH 8.0, to release the nucleic acid. The new extraction and assay procedure is used to estimate the RNA/DNA ratios of fish larvae and natural microplankton communities maintained in the laboratory under different nutritional conditions. In the two experiments, the RNA/DNA ratios were related to the nutrient availability of the organisms. The level of sensitivity of the method is experimentally set at ca. 40 ng of RNA and 10 ng DNA in the 1 ml assay, which corresponds to a minimum biomass requirement of ca. 400 ng ml-1 protein or 3 μg ml-1 dry weight. The precision, estimated at different steps of the procedure, had an overall coefficient of variation of ≤ 10%. The new approach provides RNA/DNA ratios comparable with those obtained with ethidium bromide, [ES] En este trabajo se han desarrollado los protocolos de extracción de ARN y ADN en extractos no purificados de muestras naturales de microplancton. La metodología es compatible con el ensayo fluorimétrico para ARN y ADN desarrollado por Berdalet et al. (2005). La extracción de los ácidos nucleicos se realiza combinando una rotura celular mecánica (mediante un homogeneizador manual de tejidos) con una extracción química (con 0.5% de sarcosina y 0.5 mM EDTA en tampón Tris 5 mM a pH 8). Este nuevo procedimiento de extracción y ensayo se usó para estimar los cocientes ARN/ADN en larvas de peces y comunidades naturales de microplancton mantenidos en el laboratorio bajo diferentes condiciones nutricionales. En los dos experimentos los cocientes ARN/ADN estuvieron relacionados con los nutrientes disponibles para los organismos. El nivel de sensibilidad del método fue establecido experimentalmente a aproximadamente 40 ng de ARN y 10 ng de DNA en ensayos de 1 ml, lo que corresponde a un requerimiento mínimo de biomasa de aproximadamente 400 ng ml-1 de proteína o 3 μg ml-1 de peso seco. La precisión, estimada en distintos pasos del método, tuvo un coeficiente de variación global del 10%. Esta nueva aproximación proporciona cocientes ARN/ADN comparables a las obtenidas con bromuro de etidio, This study was supported by the European funded project NTAP (EVK3-CT-2000-00022), and by the Spanish Ministry of Science through the FIL (MAR-97 09-02), ARO (MAR-99 12-02) and TURFI (REN2002-01591/MAR) projects

86th SIBS National Congress, 24-25 October 2013, Palermo, Italy.-- 1 page, 1 figure

13 pages, 7 figures, 4 tables The present study analysed the trophic ecology of the early developmental stages of four species of mesopelagic fish, the myctophids Ceratoscopelus maderensis, Hygophum benoiti and Benthosema glaciale and the sternoptychid Argyropelecus hemigymnus. These species display different morphological traits and a segregated vertical distribution throughout the water column. The study was conducted off Mallorca Island (39° N, 3° E) in the western Mediterranean, during the summer stratification period. The results indicated that feeding patterns of myctophid larvae were strictly diurnal, while in A. hemigymnus larvae, day and night feeding occurred. In the transformation stage of C. maderensis, B. glaciale and A. hemigymnus, day and night feeding was evidenced. The feeding incidence during the larval stages was low, increasing in the transformation stages, and being particularly high for A. hemigymnus. Although an increasing tendency in size and number of ingested prey was observed, the trophic niche breadth did not indicate a trophic specialization in any of the species analysed. Gut content analysis determined that diet composition was very similar among the four species, with the different developmental stages of copepods being the dominant prey throughout the early larval development. Nevertheless, in transformation stages of C. maderensis and H. benoiti, other preys, like ostracods, become important contributors to the diet. Despite the important physical and biological structuring of the water column, no differences in feeding success were observed for larvae occurring in the layers of higher biological production This research was funded by project CTM2008-04489-C03

Special issue Advances in Fisheries Research in Ibero-America.-- 9 pages, 5 figures, 3 tables, Argentinean hake, Merluccius hubbsi, is one of the most important fishery resources of the South-western Atlantic Ocean, but its spawning biomass decreased in the last fifteen years, mainly due to the increased fishing pressure. It is widely accepted that to understand recruitment variability is necessary to study the factors that determine survival of early stages of development. Nutritional condition indexes have been widely used to determine starvation in wild larvae. In the present investigation, condition of M. hubbsi larvae was estimated employing field collected material by means of RNA/DNA index. This is the first attempt to use this index in this species. The change in the RNA/DNA index showed a clear ontogenetic pattern: increasing from preflexion to postflexion stages, showing an apparent decrease at the end of postflexion stage and a conspicuous increase once transformation stage was achieved. This pattern could be indicating that the transition between postflexion and transformation stages might represent a critical phase along larval development. RNA/DNA index also showed significant differences between areas from the spawning grounds characterized by different chlorophyll a concentration and abundance of potential prey. The study of nutritional condition represents a useful tool for identifying favorable nursery areas, providing valuable information for a comprehensive management of a population subject to overfishing. © 2013 Elsevier B.V., This work was supported by the INIDEP and the CONICET, Fellowship PIP 112 200801 00815. This is INIDEP contribution N° 1846

Special issue The wrapping up of the IDEADOS project: International Workshop on Environment, Ecosystems and Demersal Resources, and Fisheries.-- 12 pages, 12 figures, 2 tables, The diel vertical distribution of fish larvae off the Balearic Islands during late autumn and summer was analysed in relation to the environmental conditions. Four fixed sampling stations, located in the outer shelf and slope zones, were sampled during both the day and night by means of oblique hauls at different water depths. In autumn the first 60. m were characterised by vertical mixing and relatively higher fluorescence values, while summer was characterised by strong near-surface stratification and the presence of a Deep Fluorescence Maximum (DFM). The fish larval community was dominated by mesopelagic species, myctophiforms and stomiiforms, with some differences in species composition and their relative contribution between periods. A higher number of species was observed to reproduce in summer. The diel vertical distribution patterns differed among species and, within species, some differences were detected between the day and night. Although their relative depth preferences were similar between surveys, seasonal comparisons for the most abundant species showed that in autumn larvae presented both a shallower distribution during the day and a deeper distribution during the night than in the summer period. The larvae of all species, except for Argyropelecus hemigymnus, were absent from layers below 200. m. In these deeper layers, only A. hemigymnus larvae and juvenile stages of myctophiforms and stomiiforms were found. Another group of species, including Hygophum benoiti, Ceratoscopelus maderensis, Cyclothone braueri and Lampanyctus crocodilus, characterised the surface assemblage, mainly appearing in the first 50. m during the day, while at night their distribution was wider, extending to deeper layers. Benthosema glaciale, Symbolophorus veranyi and Myctophum punctatum were located at intermediate levels (mostly 50-100. m). Larval size stratification was evident for the most abundant species, with younger stages being found at shallower depths in the water column, while postflexion stages presented a wide distribution at night, undergoing vertical displacement to the near-surface layers during the day. The roles of the position of the thermocline, the availability of food and light intensity as factors modulating these differences are discussed. © 2013 Elsevier B.V., This research was funded by project CTM2008-04489-C03

The present paper reports on temporalmesoscale (weeks) changes in physical and biological coupling in the cross-frontal area off the coast of Catalonia in Spain (NW Mediterranean) during the spring transition period. The effect of short-term physical variability on the spatio-temporal heterogeneity of phytoplankton biomass and in the area of overlap of the larvae of fish species dwelling on the shelf and slope is discussed. Our results indicate that the region off the Catalan coast is a dynamically active area during the spring transition period. Short-term spatio-temporal variability in the frontal system brought about significant changes in the extension of shelf and slope waters, giving rise to major changes in the spatial distribution patterns of chlorophyll and fish larvae. The relationship between integrated chlorophyll, surface chlorophyll and DCM (Deep Chlorophyll Maximum) showed important variability in a short time period. The area of overlap of the larvae of shelf and slope fish species was broad when the front was located offshore, compared to nearly complete segregation of shelf and oceanic fish larvae when the front moved inshore near the coast.

A hydrographic and zooplankton survey (neuston and water column) was performed over the Blanes submarine canyon (western Mediterranean) in June 1993. Abundance of fish and crab larvae was very low when compared with previous studies conducted in the same area. The horizontal distribution of fish and crab larvae whose adults inhabit the continental shelf was restricted to the coast. The offshore occurrence of low-salinity waters of continental origin, together with the absence of a component perpendicular to the coast in the system of currents observed throughout the study area, support the observed pattern of distribution. The occurrence of mesopelagic fish larvae and of the oceanic neustonic isopod Idotea metallica in some coastal stations may be associated with episodic inshore-offshore exchanges of water masses identified by drifting buoy trajectories.

7 pages, 5 figures, The morphology of fishes plays a very important role in the ecosystem biodiversity to show different evolutionary strategies. The morphological variations among species can be graphically represented in a morphospace and analysed using different methods. In this study we used different assemblages of mesopelagic fishes living in the Canary Islands (North-eastern Atlantic) to compare two methods: convex hull and patterning. The results demonstrated that the patterning of morphospace allowed understanding better the specific ecological strategies and structure of fish assemblages. By contrast, the convex hull is focused on a reduced number of species with a high level of morphological diversity which is located in the periphery of the morphospace. The study demonstrates that patterning analysis is a better tool for comparing these assemblages than convex hull, and it highlights the relevance of the distribution of points within the morphospace for characterizing fish assemblages, This research has been partially sponsored by the Spanish projects CTM2008-04489-C03-03 and CTM2012-39587 C04-03. Marc Farre´ Foix acknowledges a pre-doctoral grant from the Government of Andorra, ATC010-AND, academic year: 2012–2013

12 pages, 10 figures, 2 tables, [EN] The distributions of micronekton layers in the Balearic Sea (western Mediterranean) were investigated by acoustic methods. Two multidisciplinary surveys were carried out in late autumn 2009 and summer 2010, recording acoustic, biological, and hydrographic data. We described acoustic layers, migratory behavior, sampled species, and water masses processes. Acoustic modeling of gas-bearing organisms was employed to explain differences between acoustic estimates and sampled abundances. The influence of environmental variables on the vertical distribution and migration pattern of these organisms was analyzed. The thermocline depth was related to the preferred depth for migrating myctophids, while nonmigrant species dwelled in the oxygen minimum zone of the water column both in late autumn and summer periods, [FR] Deux campagnes multidisciplinaires ont été menées en automne 2009 et en été 2010, par mesures acoustique et échantillonnages biologique et hydrologique. La description des couches acoustiques, le comportement migratoire, les espèces échantillonnées et les couches d’eau sont fournies. La modélisation acoustique des organismes de type gas bearing est utilisée pour expliquer le mascage qui conduit á des différences avec les abondances mesurées. Leur préférence pour certaines gammes de variables externes dans la distribution verticale et le model de migration de ces organismes est analysée. La profondeur de la thermocline a été associée á la profondeur de migration préférée des myctophidés, de même la zone de la colonne d’eau présentant le minimum d’oxygène dissous correspond á la zone de résidence des espèces non-migrantes, tous les deux en automne et en été, This work is supported by the IDEADOS project (CTM2008-04489-C03) and the Migrants and Active Flux In the Atlantic Ocean project (MAFIA; CTM2012-39587-C04-03), both funded by the Spanish Ministry of Science and Innovation. We thank the IDEADOS team and all the colleagues that helped in the biological and hydrographic sampling