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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

In oligotrophic regions, picophytoplankton can play a key role in total carbon production and energy transfer. Since the mesoscale hydrographic variability can influence the resource availability and therefore the biological communities, here we studied the linkage between hydrography, resource supply, abundance, and biomass contribution of prokaryotic picoplankton in the south Balearic Sea during the stratified season. The sampling area covered the confluence of two different water masses, the fresher new Atlantic water, and the saltier resident Atlantic water. Our results showed higher Synechococcus abundances in the more oligotrophic new Atlantic water mass and suggest that the spatial patterns of prokaryotic picophytoplankton are dictated by the mesoscale processes in this region. The summer stratification condition separated clearly the surface mixed layer (ML) from the deep layer (DL); our results support different limiting factors for picophytoplankton in the two layers: nutrient and light availability in the ML and DL, respectively. We also obtained no significant difference in the Synechococcus biomass contribution to total autotrophic biomass within the water column, but higher contribution in the new Atlantic water mass. These results demonstrate the general importance of picophytoplankton as carbon producers in oligotrophic waters and particularly their variability as biomass source at the mesoscale, SI

16 pages, 5 figures, 2 tables, In marine ecosystems, the most significant migration observed in terms of biomass distribution is the one connected with the vertical movements in the water column. In the present study, the vertical profiles of the mesopelagic shrimps Gennadas elegans, Eusergestes arcticus, Sergia robusta, and the epipelagic Parasergestes vigilax in the Balearic Sea (western Mediterranean), during the stratified (summer) and non-stratified (autumn) hydrographic conditions, were investigated through their ontogeny, from the larval to adult stages. The mesopelagic adults were observed to move down to the deeper layers during the night more than during the daylight hours. Most larvae aggregated within the limits of the upper water column. The P. vigilax larvae were collected only during the stratified period. The first two larval stages vertical distribution indicates that the mesopelagic crustacean spawning could occur at greater depths. During the non-stratified period, the larvae of the mesopelagic species tended to remain at about 500 m depth at night, rising towards the upper layers at sunrise. Vertical patterns are discussed, as strategies associated with predator–prey trade-offs. To our knowledge, the present study is the first such attempt to jointly analyze the vertical migrations of the developmental stages of the pelagic shrimps in the Mediterranean Sea, The research was performed within the framework of the IDEADOS (CTM2008-04489-C03-01) project, funded by the National Plan I + D+i. A. P. Torres and M. Hidalgo were funded by a pre-doctoral FPI Fellowship and a post-doctoral contract, respectively, bestowed by the regional government of the Balearic Islands, Conselleria d’Educació, Cultura i Universitats, and selected as part of an operational program co-financed by the European Social Fund

Most of the Atlantic bluefin tuna caught by the purse-seine fleet in the Mediterranean Sea are transferred alive into transport cages and towed to coastal facilities where they are fattened. This major fishery is targeting aggregations of reproductive bluefin tuna that continue spawning within the transport cages. Our study is the first attempt to assess the viability of the spawning events within transport cages placed offshore in a priori favourable locations for larval survival. The study was conducted in June 2010 in the Balearic Sea, a main spawning area for bluefin tuna in the Mediterranean. The location of two transport cages, one with wild and one with captive tuna, coincide with the situation of the chlorophyll front using satellite imagery as a proxy for the salinity front between resident surface waters and those of recent Atlantic origin. The results showed that bluefin tuna eggs were spawned almost every day within the two cages but few or no larvae were found. The expected larval densities estimated after applying mortality curves to the daily egg densities observed in the cages were higher than the sampled larval densities. The trajectories of the eggs after hatching estimated from a particle tracking model based on observed geostrophic currents and a drifter deployed adjacent to the cage suggest that larvae were likely to be caught close to the cages within the sampling dates. Spawning events in captive tuna in transport cages may hatch into larvae though they may experience higher mortality rates than expected in natural populations. The causes of the larval mortality are further discussed in the text. Such studies should be repeated in other spawning areas in the Mediterranean if spawning in cages located offshore in areas favourable a priori for larval survival is likely to be considered a management measurement to minimize the impact of purse-seine fishing on tuna., La mayor parte del atún rojo atlántico capturado por la pesquería de cerco en el mar Mediterráneo es transferido vivo a jaulas de transporte y remolcado a instalaciones de engorde localizadas en la costa. Esta importante pesquería tiene como objetivo las agregaciones de reproductores de atún rojo que continúan aún su puesta en las jaulas de transporte. Nuestro estudio es el primer intento de evaluar la viabilidad del desove que tiene lugar en jaulas de transporte que están localizadas en alta mar en zonas que a priori favorecen la supervivencia larvaria. La zona de estudio está situada en el mar Balear, una de las zonas de puesta de atún rojo más importantes del Mediterráneo, en junio del 2010. La ubicación de las dos jaulas de transporte, con atún recién capturado y en cautividad respectivamente, coincide con la situación del frente de clorofila utilizando imágenes de satélite como un indicador del frente de salinidad entre aguas superficiales residentes y aquellas de origen Atlántico reciente. Los resultados muestran que hubo desove de huevos de atún rojo todos los días en las dos jaulas pero se encontraron muy pocas larvas. Las densidades de larvas que se esperaban, estimadas al aplicar curvas de mortalidad a las densidades diarias de huevos observadas en las jaulas, eran mayores que las densidades de larvas que fueron muestreadas. Las trayectorias de los huevos después de la eclosión se estimaron utilizando un modelo de deriva de partículas a partir de las corrientes geostróficas observadas y una boya lanzada junto a la jaula. Estas trayectorias sugieren que las larvas deberían haber sido capturadas cerca de las jaulas durante las fechas del muestreo. El desove de atún cautivo en jaulas de transporte puede dar lugar a larvas que posiblemente experimentan tasas de mortalidad más altas que las esperadas en poblaciones naturales. Las causas de la mortalidad larvaria se discuten más en detalle en el texto. Estudios como este deberían ser repetidos en otras zonas de puesta en el Mediterráneo. Especialmente, si el desove en jaulas ubicadas en alta mar en áreas a priori favorables para la supervivencia larvaria puede ser considerado una medida de gestión para minimizar el impacto de la pesquería de cerco en el atún rojo.

To analyze the potential trophic interactions among tuna larvae and other fish species, we studied the larval fish assemblages inhabiting the surface mixed layer around the Balearic Islands using data from two surveys carried out in summer 2006 and 2008. Despite the high diversity, Thunnus alalunga, Auxis rochei, Cyclothone pygmaea and Ceratoscopelus maderensis clearly dominated the catch in both years. The spatial distribution of several larval fish assemblages, in which tuna larvae were among the dominant species, was related to the presence of fronts and mixed Atlantic waters (AW). Different developmental stages of tuna were found in similar hydrographical scenarios. Smaller tuna larvae and plausible piscivorous tuna were found in the areas with mixed AW. Later in the season, potential piscivorous tuna were found together with small larvae from other non-tuna species that had been spawned later and transported by the fresh AW flow to offshore stations. That the different life stages of tuna co-occur with mesopelagic species in the mixed layer reveals the interesting possibility of ecological interactions between the different larvae.

19 pages, 11 figures, 3 tables, A total of 25 specimens of Eryoneicus larvae were collected near the Balearic Archipelago (Western Mediterranean Sea) in 2009 and 2010. Detailed morphological examination indicated that the smallest individual corresponded with the first zoea (ZI) stage of Polycheles typhlops hatched from a berried female by Guerao and Abelló (J Nat Hist 30(8):1179–1184, 1996). Only two species of deep-sea polychelid lobster, namely P. typhlops and Stereomastis sculpta, are known to occur in the Mediterranean. Genetic distance comparisons and phylogenetic analysis of the mitochondrial 16S rDNA and Cox I genes of this early larva together with adults from several Polycheles and Stereomastis species allowed us to assign it to P. typhlops. This is the first wild-caught larval stage of a polychelid lobster being identified using molecular techniques. The remaining specimens were attributed to zoeal stages II–III and decapodid stage based on morphological comparison. The arrangement of spines along the anterior part of the middorsal line (R, 1, 1, 1, 2, C1), characteristic of the former species E. puritanii, discriminates these larvae from other Eryoneicus found in the Mediterranean. The clear presence of epipods on the third maxilliped and pereiopods of the decapodid stage gives further support to the identification of E. puritanii as the larval stages of P. typhlops. Additionally, information on the ecology of these larvae, their abundances during different seasons, as well as their bathymetric distribution is reported, The research was carried out within the framework of the IDEADOS (CTM5008-05589 C05-01) Project funded by the Plan Nacional I + D+i. [...] A.P. Torres 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 programme cofinanced by the European Social Fund

This study aims to analyze the influence of trophic interactions on larval growth variability throughout ontogenic development using data on carbon (C) and nitrogen (N) content and isotopic composition combined with a growth study by means of otolith microstructure analysis. To fulfill this objective, Auxis rochei larvae were sampled in the Balearic Sea (NW Mediterranean). A principal components analysis distinguished 2 types of surface water masses from a total of 40 stations that showed particular hydrobiological differences—resident Atlantic water (hereafter MW) and fresh Atlantic water (hereafter AW) masses—which showed significant differences in temperature, salinity and mesozooplankton biomass. Size-fractioned zooplankton analysis revealed greater biomass in the >250 μm fraction at AW stations, while the N and C composition of this fraction was higher at MW stations. Bullet tuna from MW were significantly larger and heavier and, consequently, had a higher Fulton’s condition factor and higher daily growth rates. The δ15N and δ13C values of the zooplankton size fractions did not show significant differences between MW and AW. However, significantly higher δ13C found in MW larvae suggests differences in the origin of food supplies. Moreover, the significantly higher 15N values in bullet larvae collected in MW indicate a greater trophic specialization, possibly due to differences in the zooplanktonic food web of the water masses. Auxis rochei larvae showed a higher trophic level resulting from its higher 15N isotopic enrichment compared with the small zooplankton size fraction. The stable isotope analysis demonstrates its potential in distinguishing variable trophic pathways in early life stages of fish inhabiting open sea marine ecosystems., SI

13 pages, 7 figures, 2 tables, The complete larval series (zoea I, zoea II and megalopa) of the crab Ergasticus clouei is described and illustrated based on plankton samples from Mediterranean waters. The zoea II and megalopal stages, previously unknown, are described here for the first time. Nucleotide sequence analysis of two gene regions (16S rDNA and Cox1 genes) confirmed the assignment of these larvae to Ergasticus clouei. The molecular analyses and the morphology of the larval stages revealed large differences between Ergasticus and Inachus, the type genus of the family Inachidae. In fact, E. clouei larvae presented a series of morphological characters, such as antennal shape and mouthparts setation pattern that placed them closer to the family Oregoniidae. The phylogenetic analyses also showed significant support for the monophyly of the Oregoniidae + Ergasticus group. The data argue for removal of Ergasticus and the related genera (Bothromaia, Pleisticanthoides, Parapleisticantha and Pleistacantha) from the Inachidae and their placement within the Oregoniidae as a separate subfamily, Pleistacanthinae Števčić, 2005. Our results demonstrate that larval stages provide reliable morphological traits, independent from those of adults, to help resolving relationships among Majoidea genera, The research was carried out within the framework of the projects MEGALOPADN (CGL2009-11225) and IDEADOS (CTM2008-04489-C03), funded by the ‘Ministerio de Economía y Competividad (MINECO)’ Spanish Plan R + D + I and FEDER. F. Palero acknowledges funding from the Spanish Government, Ministry of Economy and Competitiveness (BFU2011-24112). E. Marco-Herrero and A.P. Torres acknowledge the predoctoral FPI Fellowships supported by MINECO (BES-2010-033297) and Regional Government of the Balearic Islands, Conselleria d’Educaci o, Cultura i Universitats, select as part of an operational programme co-financed by the Fondo Social Europeo, respectively

Decapod crustaceans are the main target species of deep water bottom trawl fisheries in the western Mediterranean. Despite their importance for fisheries and conservation, little is known about their larval development, especially in the case of deep water species. In this paper we present new information on the occurrence and morphology of larval stages for some species of commercial interest based on samples collected off the Balearic Islands. Mesozooplankton sampling was carried out using depth-stratified sampling devices at two stations located on the continental shelf break and middle slope, in the northwest and south of Mallorca in late autumn 2009 and summer 2010. We describe in detail the second mysis stage of the red shrimp Aristeus antennatus, not previously known, and the first larval stage of the slipper lobster Scyllarides latus, poorly described almost a hundred years ago. We also report the second finding of larvae of the spider crab Maja squinado and the first capture from the field of larval stages of the rose shrimp Parapenaeus longirostris and slipper lobster in the Mediterranean, Sí

Cannibalism among size classes may reduce starvation and improve survival of larval tuna in oligotrophic ocean areas, but it may also be a substantial mortality component depending on the availability of alternative prey. Here, we combine laboratory and field data on tuna larvae with a model of larval foraging and bioenergetics to explore the role of cannibalism in cohort development at different temperatures, durations of hatching period, hatching larval densities and natural mortality rates. Prey fields (zooplankton densities and co-occurrence of different larval stages of 3 species of tuna) were established from cruises in a main tuna spawning area around the Balearic Islands (Mediterranean Sea). Results suggest that a pure zooplankton diet is frequently insufficient to sustain larval growth. Piscivory can be a major source of larval mortality among tuna species and larvae hatched early can feed on abundant larvae of smaller size and have fewer predators themselves. We show how the intensity of cannibalism depends on the temperature dependent growth rate and the resulting relative size distribution when eggs are released continuously over a period of a few weeks. The predator-prey size distribution and the relative densities of these voracious larvae may produce overcompensation in recruitment under some environmental conditions, Sí