Invasive alien species are a major worldwide driver of biodiversity change. The current study lists verified records of non-indigenous species (NIS) in European marine waters until 2020, with the purpose of establishing a baseline, assessing trends, and discussing appropriate threshold values for good environmental status (GES) according to the relevant European legislation. All NIS records were verified by national experts and trends are presented in six-year assessment periods from 1970 to 2020 according to the European Union Marine Strategy Framework Directive. Altogether, 874 NIS have been introduced to European marine waters until 2020 with the Mediterranean Sea and North-East Atlantic Ocean hosting most of the introductions. Overall, the number of new introductions has steadily increased since 2000. The annual rate of new introductions reached 21 new NIS in European seas within the last six-year assessment period (2012–2017). This increase is likely due to increased human activities and research efforts that have intensified during the early 21st century within European Seas. As Europe seas are not environmentally, nor geographically homogenous, the setting of threshold values for assessing GES requires regional expertise. Further, once management measures are operational, pathway-specific threshold values would enable assessing the effectiveness of such measures.

The living and dead fauna of Valencia Seamount, a deep promontory in the middle of the Balearic Basin which summit is at ca. 1100 m depth, is described by first time based in a rock dredge perfomed in a sedimentary area of the summit Mount. Surface-feeder polychaetes (the Paraonidae Levinsenia gracilis and Terebellidae as dominant), and taxodont bivalves (Ledella messanensis and Yoldiella ovulum) were the main species of benthos. We found alive remains of the bamboo coral Isidella elongata, a vulnerable, habitat-forming species in the deep Mediterranean. Benthos density was low (0.6 organisms/2 dm3 mud). Thanatocoenosis evidenced a rather moderate diversity of benthic bivalves (11 species) and gastropods (9 species) also dominated by surface deposit feeders. Fish (identified/quantified from sedimented otoliths) showed diversified and abundant mesopelagic fauna, mainly Myctophidae. More interestingly, we highlighted among benthopelagic fish the occurrence of recruits of Merluccius merluccius, Micromesistius poutassou, or Hymenocephalus italicus, all species that live in the neighboring slopes of the Iberian Peninsula and the Balearic Islands at quite shallower depths (at 100-700 m) than their distribution in the Valencia Seamount summit (1102–1130 m) based on the deposited otoliths found. Some ecological aspects were discussed and the necessity to consider the deep Valencia Seamount as a potential area that should be under protection.

An intercalibration exercise on the characterisation of microplastics in marine sediment and water samples was carried out among five laboratories involved in the implementation of the Marine Strategy Framework Directive (MSFD) in their country. The samples were prepared by mixing cleaned natural sediment and sea water with microplastics sets made of particles of various polymers, shapes and colours. Overall, the errors on total counts were under 25% in absolute value. The risk of non-detection and loss of particles is greater than the risk of contamination during sample analysis. Significant differences are observed among particle types. It appears difficult to obtain reliable and comparable data on the colour of microplastics. A comparison of the errors with regards to the protocols used led to recommend NaCl [1.2 g/cm3] density separation for sediment and one filtering step (200 μm). The operators' experience appears as a key factor for the quality of the results.

The multi-species/multi-gear nature of the Mediterranean fisheries, the high number and dispersion of landing points, and the varying motivations for discarding make regulation enforcement in the basin challenging. In this study, reasons for explaining discarding are initially explored and then the main focus is on identifying potential incentive mechanisms and other measures that could reduce unwanted catches in Mediterranean trawl fisheries, in the face of the recent landing obligation. Both literature review and stakeholder engagement are employed, while special emphasis is put on the role of socio-economic tools to influence fishers' behavior. Results show that although discarding is mainly driven by market demand, a number of factors have a synergistic effect which is sometimes difficult to disentangle and capture. Regarding measures, evidence from involved stakeholders (marine scientists and fishers) shows that economic incentives but also "social measures" such as more involvement of the industry and raising awareness are offering common ground. However, specific concerns have been also expressed on measures applicability. Overall, reducing discards is a complex issue and solutions should involve a combination of management measures designed for specific fleets and regions. However, irrespective of the synthesis of the management options, it is important to create a framework of action that takes into account human behavior as a source of variability. In this context, actions that for example encourage, engage, and enable can incentivize behavioral change in order to achieve specific outcomes.

Depth and seasonal trends in the biological condition and recruitment of the red shrimp (Aristeus antennatus) have been analyzed over the slope to 2,233m in the western Mediterranean. The best biological condition of A.antennatus (gonadosomatic index [GSI]) for mating and spawning occurred at 800-1,300m in summer, in areas deeper than the fishing grounds distributed between 500 and 800 m. Females moved shallower to feed on the upper slope during periods of water-mass homogeneity (autumn-winter), increasing their hepatic gland weight (hepatosomatic index [HSI]). Females moved downslope (800-1,100m) to spawn (high GSI) during periods of water mass stratification (late spring-summer). The HSI of females decreased with depth down the slope in autumn, after the reproductive period. Small juveniles were distributed deeper than 1,000m, associated with high near-bottom O-2 levels, low turbidity and high C:N in sediments, implying favorable trophic conditions. This confirms the importance in studying the biology of deep-sea species over their entire depth range. The progressive warming and increasing salinity of deep Mediterranean waters could provoke a decrease of dissolved O-2 that would affect the life cycle of A.antennatus.

Discarding is considered globally among the most important issues for fisheries management. The recent reform of the Common Fisheries Policy establishes a landing obligation for the species which are subject to catch limits and, in the Mediterranean, for species which are subject to Minimum Conservation Reference Size (MCRS) as defined in Annex III to Regulation (EC) No 1967/2006. Additionally, several other initiatives aim to reduce unwanted catches of target and bycatch species, including species of conservation concern. This raises the need to study discarding patterns of (mainly) these species. In this work we collated a considerable amount of historical published information on discard ratios and lengths at discarding for species caught in EU Mediterranean bottom trawl fisheries. The main aim was to summarize the available historical records and make them more accessible for scientific and managerial needs, as well as to try identifying patterns in discarding. We show discard ratios and lengths at which 50% of the individuals were discarded (L50) for 15 species (nine bony fishes, three crustacean decapods and three elasmobranchs). Discard ratios were usually low for target species such as hake, red mullets and highly commercial shrimps and exemptions from the landing obligation under the de minimis rules could be sought in several cases. Discard ratios were usually higher for commercial bycatch species. Discarding is affected by a combination of factors and for a given species, especially for non-target ones, discards are likely to fluctuate within a fishery, across seasons, years and regions. For most species considered, L50s were lower than the MCRS (when in place) and length at first maturity. L50s of target species, such as hake, were very small due to the existence of market demands for small sized individuals. However, for species of low demand, like horse mackerels, a higher retention size was observed, often exceeding MCRS. Lengths at discarding are affected by legal provisions, market demands but also by biological, population and ecological traits. Understanding the factors that affect discarding constitutes the starting point for designing mitigation measures and management plans to reduce discards and improve the sustainability of the stocks.

Changes in the physiological condition (represented by Kn = body weight/length-predicted weight) of the deep-sea shrimp Aristeus antennatus associated with the warming and rising salinity trends in the western Mediterranean were analyzed to explore how deep-sea populations can reconfigure their biology to match the changes in ocean conditions. Two slope areas around the Balearic Islands (Western Mediterranean Sea) were analyzed using sampling data and generalized additive models. The 23 yr time series of monthly Kn estimates shows 2 different aspects of the life history of A. antennatus, corresponding to 2 different seasonal periods. The Kn series from June through September reflects the shrimps' reproductive condition to the north of the Islands, while samples from October through May represent a period of low gonad weight and high hepatosomatic indices to the south of the Islands. Oceanographic variables used to construct models and seek relationships with changes in Kn were salinity, temperature, and dissolved oxygen in the Levantine Intermediate Water and Western Mediterranean Deep Water layers, and chlorophyll a satellite imagery data. The North Atlantic Oscillation and the Eastern Atlantic index were used as climatic indicators. Physiologic condition during the winter fattening periods decreased over the time series and was negatively correlated with increasing salinity. During the summer reproductive periods, the best-fitting models show a year-on-year effect and a significant probability of effects on condition from oligotrophication. These results suggest that increasing salinity at depth, which ultimately increases oligotrophy, may cause changes in physiological condition.

Event Abstract Back to Event Condition and recruitment of Aristeus antennatus at great depths (to 2300 m) in the Mediterranean: environmental links and implications for management. Joan E. Cartes1*, Ana Carbonell Quetglas2 and Cristina López-Pérez1 1 CSIC, Institut de Ciencies del Mar de Barcelona, Spain 2 I.E.O., Centre Oceanogràfic de Balears, Spain Depth relationships and seasonal trends in the biological condition and recruitment of the red shrimp Aristeus antennatus have been analyzed along down to 2300 m, over all the slope in the Balearic Basin (western Mediterranean). The analysis is based on a composite year (2008-2012 period) and identifies environmental causes of the trends. We found good reproductive and general biological condition of A. antennatus (Gonado-somatic index, GSI) at 800-1300 m in summer (June-July), depths below the fishing grounds. Mating and spawning were at depths below the more saline waters of the Levantine Intermediate water mass. Recruits Smallest juveniles (recruits, ca. 1 yr age) were exclusively distributed below 1000 m, associated with high near-bottom O2 concentration, low turbidity and high C/N in sediments implying favourable trophic conditions. A seasonal migratory pattern is suggested for females, which move shallower to the upper slope during periods of water-mass homogeneity (autumn-winter) to feed in canyons, increasing their energy reserves (hepatic gland weight, HSI). Females move downslope (800-1100 m) to spawn (high GSI) during periods of water mass stratification (late spring-summer). HSI of A. antennatus females decreased linearly with depth down the slope in February and in October-November, i.e., before and after the reproductive period. This nutritional condition of females in these periods is consistent with more consumption of benthic prey (ophiuroids, polychaetes, Calocaris macandreae) at the canyon heads (Cartes, 1994) in late autumn and winter. Our results confirm/suggest: i) how important it is to study the biology of deep-sea species over the whole depth range they inhabit and not only over fishing grounds, and ii) that changes in environmental conditions linked to the progressive warming of Mediterranean Deep Water (WMDW) with a parallel increase of salinity could provoke a decrease of O2 in water masses at below 1000 m, affecting A. antennatus recruitment and its life cycle, which is extensible to other deep-sea species. Acknowledgements This study was financed within the framework of the MICYT projects BIOMARE and ANTROMARE (CTM2009-12214-C02-01-MAR), and it was also possible thanks to the multi-methological design work contained in proposals like TRENDSEAS (CTM2014-54018-C3). The authors thank all colleagues who helped us in the collection of material on the cruises for those projects, and we thank also the crew of the R/V García del Cid. References Bergström, B. I. 2000. The biology of Pandalus. Adv. Mar. Biol. 38: 55–256. Carbonell, A., Carbonell, M., Demestre, M., Grau, A., and Monserrat, S. 1999. The red shrimp Aristeus antennatus (Risso, 1816) fishery and biology in the Balearic Islands, Western Mediterranean. Fish. Res. 44: 1-13. Carbonell, A., Lloret, J., and Demestre, M. 2008. Relationship between condition and recruitment success of red shrimp (Aristeus antennatus) in the Balearic Sea (Northwestern Mediterranean). J. Mar. Syst. 71: 403-412. Carbonell, A., Grau, A., Lauronce, V., and Gómez, C. 2006. Ovary development of the red shrimp, Aristeus antennatus (Risso, 1816) from the northwestern Mediterranean Sea. Crustaceana 79(6): 727-743. Carbonell, A., dos Santos, A., Alemany, F., and Pérez-Belchi, P. 2010. Larvae of the red shrimp Aristeus antennatus (Decapoda: Dendrobranchiata: Aristeidae) in the Balearic Sea: new occurrences fifty years later. Mar. Biodiv. Rec. 3: 1-4. Carbonell, A., Llompart, P.J., Gaza, M., Mir, A., Aparicio, A., Álvarez-Barastegui, D., Balbin, R., and Cartes, J.E. Submitted. Long-term variability in the biological condition of the red shrimp Aristeus antennatus in the western Mediterranean Sea: relationships with environment. Cartes, J.E. 1994. Influence of depth and seasonality in the diet of the deep-water aristeid shrimp Aristeus antennatus in the Western Mediterranean. Mar. Biol. 120(4): 639–648. Cartes, J.E., and Sarda, F. 1993. Zonation of the deep-sea decapod fauna in the Catalan Sea (Western Mediterranean). Mar. Ecol. Prog. Ser. 94: 27-34. Cartes, J. E., and Demestre, M. 2003. Estimating Secondary Production in the Deep-water Shrimp, Aristeus antennatus (Risso, 1816) in the Catalano-Balearic Basin (Western Mediterran). J. Norhtw. Atl. Fish. Sci. 31: 355-361. Cartes, J.E., Papiol, V., and Guijarro, B. 2008. The feeding and diet of the deep-sea shrimp Aristeus antennatus off the Balearic Islands (Western Mediterranean): influence of environmental factors and relationships with biological cycle. Prog. Ocean. 79: 37-54. Cartes, J.E., Maynou, F., Lloris, D., Gil de Sola, L., and García, M. 2009a. Influence of trawl type on the composition, abundance and diversity estimated for deep benthopelagic fish and decapod assemblages off the Catalan coasts (western Mediterranean). Sci. Mar. 73(4): 725-737. Cartes, J.E., Maynou, F., Fanelli, E., Papiol, V., and Lloris, D. 2009. Long-term changes in the composition and diversity of deep-slope megabenthos and trophic webs off Catalonia (western Mediterranean): Are trends related to climatic oscillations?. Prog. Ocean. 82: 32–46. Cartes, J.E., Maynou, F., Fanelli, E. 2011. Nile damming as plausible cause of extinction and drop in abundance of deep-sea shrimp in the western Mediterranean over broad spatial scales. Prog. Ocean. 91(3): 286-294. Cartes, J.E., Fanelli, E., López-Pérez, C., and Lebrato, M. 2013a. Deep-sea macroplankton distribution (at 400 to 2300 m) in the northwestern Mediterranean in relation to environmental factors. J. Mar. Syst. 113: 75-87. http://dx.doi.org/10.1016/j.jmarsys.2013.11.018 Cartes, J.E., Fanelli, E., Lloris, D., and Matallanas, J. 2013b. Effect of environmental variations on sharks and other top predators in the deep Mediterranean Sea over the last 60 years. Climate Research 55: 239-251. Cartes, J.E., Fanelli, E., Kapiris, K., Bayhan, Y.K., Ligas, A., López-Pérez, C., Murenu, M., Papiol, V., Rumolo, P., and Scarcella, G. 2014. Spatial variability in the trophic ecology and biology of the deep-sea shrimp Aristaeomorpha foliacea in the Mediterranean Sea. Deep Sea Res. I. 87: 1-13. Cartes, J.E., Maynou, F., Fanelli, E., López-Pérez, C., Papiol, V. 2015. Changes in deep-sea fish and crustacean communities at 1000-2200 m in the Western Mediterranean after 25 years: Relation to hydro-climatic conditions. J. Mar. Syst. 143: 138-153. doi:10.1016/j.jmarsys.2014.10.015. Comeau, M., Starr, M., Conan, G.Y., Robichaud, G., and Therriault, J.C. 1999. Fecundity and duration of egg incubation for multiparous female snow crabs (Chionoecetes opilio) in the fjord of Bonne Bay, Newfoundland. Can. J. Fish. Aq. Sci. 56: 1088–1095. Company, J.B., Puig, P., Sarda, F., Palanques, A., Latasa, M., and Scharek, R. 2008. Climate Influence on Deep Sea Populations. PLoS ONE 3(1), e1431 4-16. doi.10.1371/journal.pone.0001431. Béthoux, J. P., Durrieu de Madron, X., Nyffeler, F., and Tailliez, D. 2002. Deep water in the western Mediterranean: peculiar 1999 and 2000 characteristics, shelf formation hypothesis, variability since 1970 and geochemical inferences. J. Mar. Syst. 33–34: 117–131. Demestre, M. 1990. Biología pesquera de la gamba Aristeus antennatus (Risso, 1816) en el Mar Catalán. Ph.D. Thesis, Universidad de Barcelona, Barcelona. Demestre, M., and Fortuno, J.M. 1992. Reproduction of the deep-water shrimp Aristeus antennatus (Decapoda: Dendrobranchiata). Mar. Ecol. Prog. Ser. 84: 41–51. Fanelli, E., Papiol, V., Cartes, J.E., Rumolo, P., Brunet, C., and Sprovieri, M. 2011. Food web structure of the epibenthic and infaunal invertebrates on the Catalan slope (NW Mediterranean): evidence from 13C and 15N analysis. Deep-Sea Res. I. 58(1): 98-109. Fanelli, E., Papiol, V., Cartes, J.E., Rumolo, P., and López-Pérez C. 2013. Trophic webs of deep-sea megafauna on mainland and insular slopes of the NW Mediterranean: a comparison by stable isotope analysis. Mar. Ecol. Prog. Ser. 490: 199–221. Fanelli, E., Papiol, V., Cartes, J.E., and Rodríguez-Romeu, O. 2014. Trophic ecology of the lanternfish Lampanyctus crocodilus in NW Mediterranean slopes in relation to reproductive cycle and environmental variables. J. Fish Biol. 84(6): 1654–1688. Fernández, M.V., Maltagliati, F., Pannacciulli, F.G., and Roldán, M.I. 2011. Analysis of genetic variability in Aristaeomorpha foliacea (Crustacea, Aristeidae) using DNA-ISSR (Inter Simple Sequence Repeats) markers. Comptes Rendus Biol., doi : 10.1016/j.crvi.2011.07.005. Follesa, M.C., Porcu, C., Gastoni, A., Mulas, A., Sabatini, A., and Cau, A. 2009. Community structure of bathyal decapod crustaceans off South-Eastern Sardinian deep-waters (Central-Western Mediterranean). Mar. Ecol. 30(1): 188–199. Gage, J.D., Tyler, P.A. 1991. Deep-sea biology: a natural history of organisms at the deep-sea floor. Cambridge University Press, Cambridge, U.K. pp. 1-504. Garofalo, G., Giusto, G.B., Cusumano, S., Ingrande, G., and Sinacori, G. 2007. Sulla cattura per unità di sforzo della pesca a gamberi Rossi sui fondi batiali del Mediterraneo Orientale. Biol. Mar. Medit. 14(2), 250-251. Ginger, M.L., Billett, D.S.M., Mackenzie, K.M., Kiriakoulakis, K., Neto, R.R., Boardman, D.K., Santos, V. L.C.S., Horsfall, I.M., and Wolff, G.A. 2001. OM assimilation by holothurians in the deep-sea: some observations and comments. Prog. Ocean. 50: 407-422. Guijarro, B., Díaz, P., Massutí, E., and Moranta, J. 2008. Population dynamics of the red shrimp Aristeus antennatus in the Balearic Islands (Western Mediterranean): spatial-temporal differences and influence of environmental factors. J. Mar. Syst. 71 (3-4): 385–402. Howell, K. L., Billett, D.S.M., Tyler, P.A., and Davidson, R. 2004. Feeding ecology of deep-sea seastars (Echinodermata: Asteroidea): a pigment biomarker Approach. Mar. Ecol. Prog. Ser. 266: 103–110. Hudson, I.R., Pond, D.W., Billett, D.S.M., Tyler, P.A., Lampitt, R.S., and Wolff, G.A. 2004. Temporal variations in fatty acid composition of deep-sea holothurians: evidence of bentho-pelagic coupling. Mar. Ecol. Prog. Ser. 281: 109-120. Hynes, H.B.N., 1950. The food of freshwater sticklebacks (Gasterosteus aculeatus and Pygosteus pungitius) with a review of methods used in studies of the food of fishes. J. Animal Ecol. 19: 36-58. Marra, A., Mona, S., Sà, R.M., D’Onghia, G., and Maiorano, P. 2014. Population Genetic History of Aristeus antennatus (Crustacea: Decapoda) in the Western and Central Mediterranean Sea. PloS ONE| doi:10.1371/journal.pone.0117272. Merrett, N.G., and Marshall, N.B. 1981. Observations on the ecology of deep-sea bottom-living fishes collected off northwest Africa (08°-27°N). Prog. Ocean. 9: 185-244. McCullagh, P., and Nelder, J.A. 1989. Generalized Linear Models, 2nd edn, Chapman & May, London, pp. 1-511. Morales-Nin, B., Sarda, F., Maynou, F., Cartes, J.E., Moranta, J., Massutí, E., Company, J.B., Rotllant, G., Bozzano, A., and Stefanescu, C. 2003. Size influence and zonation patterns in fishes and crustaceans from the deep water communities of the Western Mediterranean. J. N.A.F.O. 31: 401-413. Palmas, F., Addisi, P., Cabiddu, S., Cuccu, D., Follesa, M.C., Mura, M., Olita, A., Pesci, P., and Sabatini, A. 2015. Distribution of spawning and nursery grounds for deep–water red shrimps in the central western Mediterranean Sea. Medit. Mar. Sci. 16(1), 117-127. Papiol, V., Cartes, J.E., and Fanelli, E. 2014. The role of food availability in regulating the feeding dynamics and reproductive cycles of bathyal benthopelagic fish in the northwest Mediterranean slope. Limn. Ocean. 59(5): 1779–1794. Pezzuto, P.R., Alvarez Perez, J.A., and Wahrlich, R. 2006. Deep-sea shrimps (Decapoda: Aristeidae): new targets of the deep-water trawling fishery in Brazil. Brazil J. Ocean. 54: 2-3. Relini Orsi, L., and Pestarino, M. 1981. Riproduzione e distribuzione di Aristeus antennatus (Risso, 1816) sui fondi batiali liguri. Nota preliminare. Quad. Lab. tecn. pesca 3(1 suppl.): 123-133. Rohling, E.J., and Bryden, H.L. 1992. Man induced salinity and temperature increase in the western Mediterranean deep water. J. Geophys. Res. 97C: 191–198. Roldán, M.I., Heras, S., Patellani, R., and Maltagliati, F. 2009. Analysis of genetic structure of the red shrimp Aristeus antennatus from the Western Mediterranean employing two mitochondrial regions. Genetica 136: 1-4. doi: 10.1007/s10709-008-9330-2 PMID: 19593873 Rumolo, P., Cartes, J.E., Fanelli, E., Papiol, V., Sprovieri, M., Mirto, S., Gherardi, S., and Bonanno, A. 2015. Seasonal variations in Keywords: deep sea, Biological condition, recruitment, spawining, Aristeids Conference: XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016. Presentation Type: Poster Presentation Topic: 1. ECOLOGY, BIODIVERSITY AND VULNERABLE ECOSYSTEMS Citation: Cartes JE, Carbonell Quetglas A and López-Pérez C (2016). Condition and recruitment of Aristeus antennatus at great depths (to 2300 m) in the Mediterranean: environmental links and implications for management.. Front. Mar. Sci. Conference Abstract: XIX Iberian Symposium on Marine Biology Studies. doi: 10.3389/conf.FMARS.2016.05.00141 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 29 Apr 2016; Published Online: 03 Sep 2016. * Correspondence: Dr. Joan E Cartes, CSIC, Institut de Ciencies del Mar de Barcelona, Barcelona, Catalonia, 08003, Spain, jcartes@icm.csic.es Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Joan E Cartes Ana Carbonell Quetglas Cristina López-Pérez Google Joan E Cartes Ana Carbonell Quetglas Cristina López-Pérez Google Scholar Joan E Cartes Ana Carbonell Quetglas Cristina López-Pérez PubMed Joan E Cartes Ana Carbonell Quetglas Cristina López-Pérez Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

This research provides an evaluation of the quality and health status of some locally abundant fish species, usually otter-trawl bycatch species. The study was conducted in the southern and eastern Spanish Mediterranean coast. Mean concentration of heavy metals in muscle and parasitisation indices showed moderate levels. Higher lead concentration was found in fish from the western Alboran and arsenic, cadmium and mercury were more present on fishes from the eastern Alboran area, although most species analysed contain moderate levels of heavy metals in muscle. Concerning parasitisation, F. Anisakidae nematodes were present in all the species, except sardine. Only mercury showed a positive relationship with parasitisation. We also considered three feeding guilds. Metal mean concentrations were higher in benthivores and more littoral fishes. Pelagic planktivores species are the healthiest and the more suitable for consumers from the sanitary point of view.

While large-scale patterns of pelagic marine diversity are generally well described, they remain elusive at regional-scale given the high temporal and spatial dynamics of biological and local oceanographic processes. We here evaluated whether the main drivers of pelagic diversity can be more pervasive than expected at regional scale, using a meroplankton community of a frontal system in the Western Mediterranean. We evidence that regional biodiversity in a highly dynamic ecosystem can be summarized attending to both static (bathymetric) and ephemeral (biological and hydrographical) environmental axes of seascape. This pattern can be observed irrespectively of the regional hydroclimatic scenario with distance to coast, salinity gradient and chlorophyll a concentration being the main and recurrent drivers. By contrast, their effect is overridden in common analyses given that different non-linear effects are buffered between years of contrasting scenarios, emerging the influence of secondary effects on diversity. We conclude that community studies may reveal hidden persistent processes when they take into account different functional effects related to hydroclimatic variability. A better understanding of regional dynamics of the pelagic realm will improve our capability to forecast future responses of plankton communities as well as impacts of climate change on marine biodiversity.

The complexity of the natural processes lead to many nonlinear interacting factors that influence the distribution and survival of marine pelagic species, particularly in their larval phase. The management of these ecosystems requires techniques that unveil those interactions by studying the system globally, including all relevant variables and combining both community and environmental data in a single step. Specifically, we apply an unsupervised neural network, the Self-Organising Map (SOM), to a combined dataset of environmental and decapod larvae community data from the Balearic sea, obtained in two years with contrasting environmental scenarios, as an Exploratory Data Analysis (EDA) technique that provides a global and more detailed view of both the environmental processes and their influence on the distribution of such planktonic community.We examine the parental influence on the initial larval distribution by aggregating data by adult habitat, which also increments the signal to noise ratio (mean data patterns over noise due to outliers or measurement errors), and consider the distribution of larvae by development stage (as a proxy of age and hence of potential dispersion). The joined study of parental effect, drifting or concentration events determined by dynamical processes in the whole water column, and lifespan, draws the possible paths followed by larvae, and highlights the more influencing variables in their distribution. Investigation of the different aspects of dynamic height (absolute values, gradients or edges and correlations) clarified the effect of the oceanographic processes on decapods' larvae. (C) 2014 Elsevier Ltd. All rights reserved.

The decapod larvae community inhabiting the Balearic Sea surface waters was studied from plankton surveys carried out in the spring and summer of 2004 and 2005 between 38°N 0.5°E and 42°N 6°E. A total of 84 taxa were identified, from seven taxonomic orders. The mean larval densities varied from 0.01-240 (±11.69) individuals 100 m−3in 2004 to 0.40-600 (±26.89) individuals 100 m−3in 2005. The analysis of larval spatial patterns in relation to the observed inter-annual environmental variability indicated that they were associated with the different hydrodynamic conditions. In 2004, mesoscale gyres, both anticyclonic and cyclonic, influenced the surface larval distribution by trapping and retaining larvae near the islands, and these larvae constituted an identifiable community different from a second one occupying the oceanic area, characterized by the presence of mesopelagic species larvae. In 2005, most of the area was occupied by resident surface Atlantic waters, which hindered the northern progression of fresher recent Atlantic waters. This environmental homogeneity resulted in a less contrasting scenario, and a unique community including larvae both of neritic and oceanic decapod species was found in most stations. The contrasting hydrographical situations studied in these years allowed to detect shift boundaries in the larval distribution of neritic species, indicating that the hydrographically more homogeneous years may lead to a higher dispersion of neritic decapod larvae.

The Mediterranean Sea is one of the world's hotspots for marine bio-invasions. Most invasions are first documented based on an initial record of occasional adult captures. However, reports of larval stages could indicate that there is an adult population that is reproducing and therefore well established in the area. The spread of the oriental shrimp, Palaemon macrodactylus, from its native estuarine waters of southeast Asia to new regions worldwide is well documented. We report the first record of this species in the Mediterranean based on the presence of its larval stages in plankton samples. Decapod larvae were collected in five offshore plankton surveys performed off the Balearic Islands (western Mediterranean), and zoeae III and VI of the oriental shrimp were found among them. Taking into account the duration of the successive developmental stages, and the hydrodynamic characteristics of the study area, these larvae were most probably spawned by adult populations not yet documented. The larvae were found in marine waters despite the fact that adults usually inhabit brackish waters. Our study is a good example of how plankton studies can help to detect larval stages of invasive species before the adult populations are detected.