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21 pages, 8 figures, 1 table, supporting information https://doi.org/10.1111/mec.16840.-- Data Availability Statement: Raw reads have been deposited to European Nucleotide Archive (ENA) under the accession id PRJEB45992. A VCF file with all filtered and unlinked SNPs used in the analyses of this study is provided as an additional file., By evaluating genetic variation across the entire genome, one can address existing questions in a novel way while raising new ones. The latter includes how different local environments influence adaptive and neutral genomic variation within and among populations, providing insights into local adaptation of natural populations and their responses to global change. Here, under a seascape genomic approach, ddRAD data of 4609 single nucleotide polymorphisms (SNPs) from 398 sardines (Sardina pilchardus) collected in 11 Mediterranean and one Atlantic site were generated. These were used along with oceanographic and ecological information to detect signals of adaptive divergence with gene flow across environmental gradients. The studied sardines constitute two clusters (FST = 0.07), a pattern attributed to outlier loci, highlighting putative local adaptation. The trend in the number of days with sea surface temperature above 19°C, a critical threshold for successful sardine spawning, was crucial at all levels of population structuring with implications on the species' key biological processes. Outliers link candidate SNPs to the region's environmental heterogeneity. Our findings provide evidence for a dynamic equilibrium in which population structure is maintained by physical and ecological factors under the opposing influences of migration and selection. This dynamic in a natural system warrants continuous monitoring under a seascape genomic approach that might benefit from a temporal and more detailed spatial dimension. Our results may contribute to complementary studies aimed at providing deeper insights into the mechanistic processes underlying population structuring. Those are key to understanding and predicting future changes and responses of this highly exploited species in the face of climate change, This study was carried out within the European Research Contract SPELMED (EASME/EMFF/2016/032) funded by the Executive Agency for Small- and Medium-sized Enterprises (EASME) of the European Commission (DGMARE). [...]. MC would like to acknowledge partial funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 869300 (FutureMARES). MC and FR acknowledge the institutional support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S). FR was supported by the Ramón y Cajal programme (Spanish Ministerio de Ciencia e Innovación, RYC2020-030078-I). This research was supported in part through computational resources provided by IMBBC (Institute of Marine Biology, Biotechnology and Aquaculture) of the HCMR (Hellenic Centre for Marine Research). Funding for establishing the IMBBC HPC has been received from the MARBIGEN (EU Regpot) project, LifeWatchGreece RI and the CMBR (Centre for the study and sustainable exploitation of Marine Biological Resources) RI, implemented under the Action “Reinforcement of the Research and Innovation Infrastructure,” funded by the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014-2020) and cofinanced by Greece and the European Union (European Regional Development Fund)

10 pages, 4 figures, 6 tables, supplementary data https://doi.org/10.1016/j.ecss.2021.107699, Sardine and anchovy have shown important changes in landings, biomass, abundance and body condition with time in the Western Mediterranean Sea. Several hypotheses have been proposed to explain these changes, including the negative interaction with jellyfish blooms. Increases in jellyfish blooms may be one of the reasons for a decline in these fish stocks because several jellyfish species have been shown to feed on fish larvae and juveniles. The main aim of the present study was to test the plausible relationship between jellyfish blooms and stock dynamics (abundance, biomass, and fitness) of anchovy and sardine, and its fisheries within an ecological context of the western Mediterranean Sea. Our main hypothesis was that jellyfish blooms, in combination with other environmental drivers, could have negative effects due to their predation on early stages of small pelagic fish (direct mortality) or due to predation on zooplankton, which is also prey of the small pelagic fish at different ontogenetic stages (direct competition). To test our hypothesis, we developed Bayesian Generalized Linear Mixed Models to compare landings, biomass, abundance, and Kn condition factor of both species with several climatic indices, oceanographic variables, and the occurrences of jellyfish blooms. Our results revealed that the jellyfish bloom occurrence had a high probability of negatively and broadly affecting both species in addition to changes in environmental conditions. This suggests that jellyfish blooms should be added to the likely causes of change when analyzing small pelagic fish change, This study was carried out within the Spanish Research project PELWEB (CTM2017-88939-R) funded by Spanish Ministry of Science, Innovation and Universities, and the Catalonian Government PELCAT projects (CAT 152CAT00013, TAIS ARP059/19/00005). [...] MC acknowledges the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) to the Institute of Marine Science (ICM-CSIC).

The degree of exposure of fishing communities to environmental changes can be partially determined by the vulnerability of the target species and the landings composition. Hence, identifying the species that ecologically most contribute to the vulnerability of the landings are key steps to evaluate the risk posed by climate change. We analyse the temporal variability in intrinsic sensitivity and the ecological vulnerability of the Portuguese fisheries landings, considering the species proportions derived both from the weights and revenues. To account for the diversification of species of each fleet, we explored the species dependence of the fishery in combination with the vulnerability of them. The analyses were carried out separately for three fleet typologies and three regions. Opposite to what has been observed at a global scale, the ecological sensitivity of the fisheries landings between 1989 and 2015 did not display a decline across areas or fishing fleets. Considering each fleet independently, for trawling, where average vulnerability was lower than in the other fleets, the sensitivity of the landings increased since the 2000s. On the other hand, the high vulnerability found in multi-gear fleets was compensated by diversification of the species caught, while purse-seine fleets targeted low vulnerability species but presented a high fishery dependence on few species. The results highlight the importance of combining information on ecological vulnerability and diversification of fishing resources at a regional scale while providing a measure of the ecological exposure to climate change. Fundação para a Ciência e a Tecnologia | Ref. UIDB/04326/2020 Fundação para a Ciência e a Tecnologia | Ref. SAICT-45-2017-02 Fundação para a Ciência e a Tecnologia | Ref. ALG-01- 0145-FEDER-028518 Fundação para a Ciência e a Tecnologia | Ref. PTDC/ASP-PES/28518/2017 Fundação para a Ciência e a Tecnologia | Ref. MAR-01.03.02-FEAMP-0052 Fundação para a Ciência e a Tecnologia | Ref. FCT DL57/2016/CP1361/CT0008

16 pages, 7 figures, 3 tables, supplementary material https://doi.org/10.3354/meps12962, The recent northward expansion of the round sardinella Sardinella aurita in the Mediterranean Sea has been documented as a consequence of rising sea temperature. At the same time, declines in sardine and anchovy biomass have been observed in the NW Mediterranean Sea, necessitating an assessment of whether the expansion of round sardinella may affect sardine and anchovy populations. Here, we combined stomach content and isotopic analyses to describe the trophic habits of round sardinella in the NW Mediterranean Sea and its trophic relationships with 2 sympatric small pelagic fish, European anchovy Engraulis encrasicolus and European pilchard Sardina pilchardus. Results revealed changes in the diet of round sardinella during the year. In summer, the most important prey were copepods (Acartia spp.) and cladocerans (Penilia avirostris). During winter, the diet was composed mainly of copepods and tunicates (mainly appendicularians), but microplankton was also numerically important in adult diets. In contrast to previous studies, during spring, round sardinella principally fed on salps (Thaliacea). To our knowledge, this is the first time that salps have been identified as an important prey for round sardinella. When compared to coexisting small pelagic fish, we found that round sardinella adults had a different trophic niche than anchovy and sardine. In contrast, round sardinella juveniles partially overlapped the trophic niche with the juveniles of the other 2 species. Therefore, the range expansion of round sardinella probably would not affect sardine and anchovy populations. Only in a situation of food limitation could juveniles of round sardinella compete with and affect both sympatric species. Our results provide new insights into the ecological role of this range-expanding species in the NW Mediterranean Sea, and highlight the importance of gelatinous zooplankton as prey, We also thank the General Fisheries Commission for the Mediterranean Sea (GFCM) for their financial support to present this work at the International Symposium on drivers of dynamics o small pelagic fish resources. This study was funded by ECO-TRANS (CTM2011-26333) and PELWEB (ES-PN-2017-CTM2017-88939-R) projects. M.A.P. was funded by an FPI grant and a Short-Stay FPI grant (BES-2012-054267; Spanish Government). J.N. was funded by a Ramon y Cajal contract (RYC-2015-17809) of the Spanish Government

7 figures, 2 tables, European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are crucial species for the marine ecosystem of the Northwestern Mediterranean Sea. They account for a high percentage of fish landings and they represent an important economic income. Concerns over their stock status are rising in recent years as biomass, growth, reproductive capacity and body condition of both species are declining. Therefore, there is an urgent need for a continuous and fast body condition monitoring scheme. Energy storage variability has important implications for both fish recruitment and population structure. Direct condition indices, such as bomb calorimetry, are highly reliable for measuring the energy content, but extremely time-consuming. Alternatively, fatmeter analysis and relative condition index (Kn) have been proposed as effective indirect methods. The aim of this study is to test the application of fatmeter as a surrogate of bomb calorimetry to infer the energy content of both small pelagic fishes. For the validation, fatmeter values were compared with both energy density (ED; via bomb calorimetry) and Kn values. Individuals of both species were sampled monthly in Barcelona harbor for a year in order to assess seasonal variations in energy content. Our results highlight that fatmeter measurements are strongly correlated with calorimetry for sardine, while a weaker but significant correlation was found for anchovy. The observed differences between the two species are related to their breeding strategies. Based on this study, fatmeter analysis appears to be a faster and suitable method to evaluate the energy content of both species routinely., In addition, we provide a linear model to infer ED from fatmeter values of both small pelagic fish. Eventually, these findings could allow for the avoidance of bomb calorimetry and could be used to implement body condition monitoring protocols, and to boost continuous large-scale monitoring, This work was supported by PELWEB [ES-PN-2017-CTM2017-88939-R] project. C.C. was funded by an Erasmus+ Mobility for Traineeships scholarship, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

17 pages, 7 figures, 3 tables, supporting Information https://doi.org/10.1002/ece3.8293.-- Data availability statement: All the DNA metabarcoding raw reads of prey species obtained from the stomach contents were deposited in the BioProject database (Gen-Bank, NCBI, 1988) as BioProject PRJNA653773. All other data used in the manuscript are included in the manuscript or as Supporting Information, The northward expansion of round sardinella (Sardinella aurita) in the Mediterranean Sea, together with declines and fluctuations in biomass and landings of European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) observed in recent decades, may suggest potential inter-specific competition in the pelagic domain. The coexistence of sympatric zooplanktivorous fish species might therefore be exposed in part to trophic niche overlap and competition for food. Combining visual diet characterization under the microscope with DNA metabarcoding from stomach contents of fish collected in spring results show that predation on relatively large krill is equally important for sardinella than for the other two niche overlapping species. Furthermore, an important overlap is found in their isotopic niche, especially with anchovy, using nitrogen (δ15N) and carbon (δ13C) stable isotopes in muscle tissue. In fact, the three fish species are able to feed effectively in the whole prey size spectrum available during the sampled season, from the smallest diatoms and copepods to the larger prey (i.e., decapods and euphausiids), including fish larvae. Moreover, effective predation upon other large prey like siphonophores, which is observed only when multi-proxy analyses in stomach contents are applied, might also be relevant in the diet of sardinella. The overlapping diet composition in spring, together with the effective use of food resource by sardinella, can be of special interest in potential future scenarios with warmer water temperature leading to lower zooplankton and/or higher jellyfish availability, where sardinella may take advantage over other species due to its feeding plasticity, This study was partially funded by the projects PELWEB (ES-PN-2017-CTM 2017-88939-R) and PELCAT (CAT 152CAT00013, TAIS ARP059/19/00005). MEDITS data collection has been co-funded by the EU through the European Maritime and Fisheries Fund (EMFF) within the National Program of collection, management, and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy. This work acknowledges the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S) to the Institute of Marine Science (ICM-CSIC)

7 pages, 3 figures, 4 tables, Understanding the trophic ecology of marine predators is pivotal to assess their ecological role in the ecosystems and develop management actions. Despite the ecological importance of predatory pelagic fish species, the trophic role that individual species play within marine communities in many marine basins, such the Mediterranean Sea, remains unclear. In the present study, we aimed to provide new integrative information about the trophic ecology at different temporal scales of Atlantic bonito (Sarda sarda), little tunny (Euthynnus alletteratus) and swordfish (Xiphias gladius) in the north-western Mediterranean Sea. To quantify the trophic habits of these three species, we used stable isotopic analysis and isotopic mixing models from different tissues that integrate trophic information at different temporal scales (~1 month for liver, ~ several months for muscle, >1 year for fin). We found clear and consistent differences in the trophic habits among the three species and time spans within the same species. Although preying mainly on clupeiforms, Atlantic bonito and little tunny present a temporal segregation in the species preference, with Atlantic bonito preying mainly on European sardine and round sardinella at long-term, while little tunny preyed mainly on European anchovy. In the other hand, swordfish shows a more generalist trophic strategy with high preference for demersal prey. This study emphasises the utility of this integrative approach for trophic studies due to its capacity for monitoring trophic habits over different time spans, J.N. was supported by the Spanish National Program Ramon y Cajal (RYC-2015-17809). This study is a contribution to the project PELWEB (CTM 2017-88939-R, Ministry of Science and Innovation, Spain) and to the Master-thesis of PES, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

11 pages, 8 figures, 2 tables, Variability in body condition and energy storage has important implications for fish recruitment and ecosystem structure. Understanding strategies for energy allocation to maintenance, reproduction and growth is essential to evaluate the state of the fish stocks. In this study, we address the energetics dynamics of the annual cycle of anchovies (Engraulis encrasicolus) and sardines (Sardina pilchardus) in the north-western Mediterranean Sea using indirect and direct condition indices. We assessed and validated the use of morphometric, biochemical and energetic indices for both species. Annual patterns of the relative condition index (Kn), gonadosomatic index (GSI), lipid content (% lipids) and energy density (ED) were linked to the energy allocation strategy. Our results highlight that anchovy mainly rely on income energy to reproduce, while sardine accumulate the energy during the resting period to be used in the reproduction period. Consequently, variability in the lipid content and ED between seasons was lower in anchovy than in sardine. In both species, we observed an early decline in energy reserves in late summer-early fall, which may be related to unfavourable environmental conditions during spring and summer. Regarding the use of different condition indices, both direct indices, lipid content and ED, were highly correlated with Kn for sardine. ED was better correlated with Kn than lipid content for anchovy. For the first time, a relationship between ED of gonads and GSI for sardine and anchovy was provided, highlighting the importance of the energy invested in reproduction. This work provides new insights into the energy dynamics of sardine and anchovy. We also demonstrate which are the most suitable indices to measure changes in the physiological condition of both species, providing tools for the future monitoring of the populations of these two commercially and ecologically important fish species, This study was funded by ECOTRANS (Ministry of Economy and Competitiveness, Spain; CTM2011-26333) and PELWEB (Ministry of Science and Innovation, Spain; ES-PN-2017-CTM2017-88939-R) projects. A.A.-P was funded by a Predoctoral reserach grant (Ministry of Economy and Competitiveness, Spain; CTM2011-26333). J.N. was funded by a Ramon y Cajal contract (Ministry of Science and Innovation, Spain ;RYC-2015-17809, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

18 pages, 5 figures, 6 tables, supplementary information https://doi.org/10.1038/s41598-020-74602-y, This work combines state-of-the-art methods (DNA metabarcoding) with classic approaches (visual stomach content characterization and stable isotope analyses of nitrogen (δ15N) and carbon (δ13C)) to investigate the trophic ecology of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) at high taxonomic and spatial resolution in the Western Mediterranean Sea. Gut contents observed are in accordance with the dietary plasticity generally described for anchovy and sardine, suggesting a diet related to the opportunistic ingestion of available prey in a certain area and/or time. Genetic tools also showed modest inter-specific differences regarding ingested species. However, inter-specific and intra-specific differences in ingested prey frequencies and prey biomass reflected a latitudinal signal that could indicate a more effective predation on large prey like krill by anchovy versus sardine, as well as a generalized higher large prey ingestion by both species southwards. In fact, both species presented lower δ15N in the northernmost area. This latitudinal gradient indicates changes in the trophic ecology of anchovy and sardine that coincide with previously described better biological conditions for fish in the southern part of the study area as well as higher landings of both species in recent years, This study was partially funded by the projects PELWEB (ES-PN-2017-CTM 2017-88939-R) and PELCAT (CAT 152CAT00013, TAIS ARP059/19/00005). MEDITS data collection has been co-funded by the EU through the European Maritime and Fisheries Fund (EMFF) within the National Program of collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

17 pages, 6 figures, 6 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2020.566686/full#supplementary-material.-- The raw data supporting the conclusions of this article will bemade available by the authors, without undue reservation, Improving the knowledge on the biology, ecology and distribution of marine resources exploited by fisheries is necessary to achieve population recovery and sustainable fisheries management. European hake (Merluccius merluccius) is one of the most important target species in the Mediterranean Sea and is largely overexploited by industrial fisheries. Here, we used two methodological approaches to further investigate the seasonal variation in the spatial distribution of European hake considering ontogenetic changes and trophic ecology in the western Mediterranean Sea. Our main aim was to explore if spatial changes in hake distribution were related to trophic behavior, in addition to key environmental factors. We employed a hierarchical Bayesian species distribution modeling approach (B-SDM), using spatial data from two oceanographic surveys conducted during winter and summer. We analyzed how the environmental variables, together with abundance and mean weight distribution of the main preys identified for European hake, affected the seasonal distribution of the species. Results revealed clear differences in the distribution of the European hake between seasons, which were indeed partially correlated to the distribution of their main preys, in addition to the environment. Stable isotope values and Bayesian isotopic mixing models (MixSIAR) revealed substantial seasonal and ontogenetic differences in trophic habits of European hake, partly matching the spatial distribution results. These findings could have implications for a future seasonal-based adaptive fisheries management, as local depletion of prey, or variation in size and condition may affect European hake presence in this area. Moreover, this study illustrates how the sequential application of methodologies provides a more holistic understanding of species seasonality, which is essential to understand the phenological processes of exploited species and their potential shifts due to environmental changes, This study is a contribution of the projects PELWEB (CTM2017-88939-R) and RESNEP (CTM2017-82991-C2-1-R) of the Spanish Ministry of Economy and Competiveness of Spain). [...] This study took advantage of data collected under the ECOTRANS projects (CTM2011-26333, 2012–2014, Spanish Ministry of Economy and Competiveness, Spain). EL-L was supported by a FPU grant (FPU1704395, Spanish Ministry of Education). JN was supported by the Spanish National Program Ramón y Cajal (RYC-2015-17809, Spanish Ministry of Economy and Competiveness, Spain). Also funded by Project IMPRESS (RTI2018-099868-B-I00) project, ERDF, Ministry of Science, Innovation and Universities – State Research Agency., With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

10 pages, 6 figures, 1 table, supplementary data https://doi.org/10.1016/j.marpolbul.2020.111399, We quantified the incidence of microplastics in the gut contents of the European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) in the Northwestern Mediterranean Sea and tested which variables influence this abundance, including the prevalence of parasites (i.e., trematoda larvae and nematodes). We detected a 58% occurrence of microplastics ingestion in sardines and a 60% in anchovies. With respect to sardines, the individuals with lower body conditions were found to have the highest microplastics ingestion probabilities, whereas in anchovies such probabilities were observed in individuals with higher gonadosomatic indices and smaller size. The areas with the highest microplastics ingestion probabilities were the Gulf of Alicante for sardines and the Gulf of Lion - Ebro Delta for anchovies. Both species showed a positive relationship between parasites and microplastics ingestion. These results highlight that both parasitism and ingestion of microplastics are concerns for the health of marine stocks and human consumers, This study was carried out within PELWEB (CTM2017-88939-R) and PELCAT (CAT 152CAT00013, TAIS ARP059/19/00005) projects. [...] MEDITS data collection has been co-funded by the EU through the European Maritime and Fisheries Fund (EMFF) within the National Program of collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Contribution to the Theme Section ‘Drivers of dynamics of small pelagic fish resources: biology, management and human factors’.-- 18 pages, 4 figures, 8 tables, Important changes have been observed in recent decades in small pelagic fish (SPF) populations of the NW Mediterranean Sea: Declines in biomass and landings of European anchovy and sardine, and a geographical expansion of round sardinella. These changes have been linked to environmental factors directly influencing annual recruitment and growth. The role of climate change in affecting the composition of plankton has also been suggested to explain declines in SPF, while other causes could be the recovery of predators, competition with other pelagic organisms that prey on early life phases of SPF (i.e. gelatinous zooplankton), interspecific competition for food, or impacts from fisheries harvest. To test the role of these potential pressures, we developed qualitative mathematical models of a NW Mediterranean pelagic food web. We used analyses of sign directed graphs and Bayesian belief networks to compare alternative hypotheses about how SPF species may have responded to combinations of different pressures. Data documenting changes in SPF populations were used to test predicted directions of change from signed digraph models. An increase in sea surface temperature (SST) that had either a positive impact on round sardinella or on gelatinous zooplankton abundance was the pressure that alone provided the most plausible insights into observed changes. A combination of various pressures, including an increase in SST, an increase of exploitation and changes to zooplankton also delivered results matching current observations. Predators of SPF were identified as the most informative monitoring variable to discern between likely causes of perturbations to populations of SPF, This study was funded by the ECO-TRANS (CTM2011-26333; Spanish Ministry of Economy and Competitivity), SafeNET (EU-DGMARE MARE/2014/41) and PELWEB (ES-PN-2017-CTM2017-88939-R) projects. M.A.-P. was funded through an FPI grant from the Spanish government. J.N. was supported by the Spanish National Program Ramón y Cajal

12 pages, 3 figures, 3 tables, supplementary data https://doi.org/10.1016/j.marenvres.2021.105381, We investigated the main drivers of eggs and larvae distributions of European sardine and anchovy from the NW Mediterranean Sea. We used Generalized Additive Models and satellite environmental data. Mainly sea surface temperature, but also currents, surface height, and primary production were significantly correlated with both species’ early stages distributions. Anchovy optimal temperature upper limit was not detected, but sardine eggs and larvae presented a small-ranged bell-shape curve relationship to SST with an upper SST threshold around 13 °C. Sardine spawning during winter appeared to be dependant not only on in-situ environmental conditions but also on summer conditions prior to the spawning event. Model predictions of the larval and spawning habitat distribution showed clear differences between developmental stages and between species, confirming a worsening of the sardine habitat with time. Considering the further increase of surface temperature predicted in the years to come, the survival of the sardine in the region could be compromised, F.G-V. was supported by Erasmus+ Mobility for Traineeships scholarship (European Union). This study took advantage of data collected under the ECOTRANS Project (“Dynamics and ecological role of small pelagic fishes in the North Western Mediterranean: energy transfer from planktonic organisms to top predators”, National Spanish Plan, CTM2011-26333, 2012–2014) and is a contribution to the PELWEB project (“Winners, losers and shifts of PELagic food WEB changes in the western Mediterranean Sea: from ecosystem consequences to future projections”, CTM2017-88939-R, 2018–2020). MGP would like also to thank the project IMPRESS (RTI2018-099868-B-I00) project, ERDF, Ministry of Science, Innovation and Universities - State Research Agency. This work acknowledges the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) to the Institute of Marine Science (ICM-CSIC)

11 pages, 6 figures, 1 table, supplementary data https://doi.org/10.1016/j.rsma.2020.101606, European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are two of the most important small pelagic fish species in terms of biomass and commercial interest in the Mediterranean Sea. Their populations are clearly influenced by environmental variations, making them good bio-indicators of climate-driven changes. Here, we reviewed the different environmental factors documented to affect anchovy and sardine biology by using a systematic review approach on methodologies used to study environmental effects on these species, variables identified to play a role, and relationships found between ecological variables and the environment. Our results show that available studies were heterogeneously distributed, being more abundant for anchovy adults in the Western Mediterranean. Among all the environmental factors found significant, temperature, depth, salinity and chlorophyll-a concentration were the most studied for both species. Further emphasis was placed on the effect of these four variables, with various relationships found for the different life stages and areas. This review provides a general insight of what is known about how the environment influences growth, spawning, abundance and distribution of anchovy and sardine in the Mediterranean Sea, and identifies gaps of knowledge for future research. Our study sets a knowledge baseline for future studies about climate variability and change in the Mediterranean basin, This study was made under the auspices of PELWEB and SPELMED projects. PELWEB project is funded by the Spanish Ministry of Sciences and Innovation (ES-PN-2017-CTM2017-88939-R) and SPELMED project was funded by the EU DGMARE (SC NR 02-TENDER EASME/EMFF/2016/32) project, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

8 pages, 3 figures, 3 tables, The ommastrephid squid, Illex coindetii, is one of the most abundant cephalopods in the Mediterranean Sea and an important predator in the ecosystem. In the present study, we examined the diet habits of I. coindetii in the north-western Mediterranean Sea by combining two complementary approaches: stomach content and stable isotopic analyses. Specifically, we examined whether the diet differed between sizes and seasons. Stomach content results indicated that the diet of I. coindetii was composed of 35 prey items including four major groups; namely the crustaceans Pasiphaea sivado, Amphipods, squid of the Order Teuthida, and pelagic and mesopelagic fish. Differences were found among different ontogenetic sizes: juvenile individuals fed mainly on crustaceans (%IRI = 77.59), whereas adult individuals fed on a wider range of prey items, including the shrimp P. sivado (%IRI = 33.21), the amphipod Anchylomera blossevillei (%IRI = 0.91), the decapod Plesionika sp. (%IRI = 0.19), the carangid Trachurus trachurus (%IRI = 0.34) and some Myctophids species (%IRI = 0.21). Differences were also found between seasons in the year. In winter, crustaceans were the main prey items, whereas in summer the diversity of prey was higher, including fish, crustaceans and molluscs. Similar to the stomach contents, stable isotopic results indicated differences among sizes. δ15N values were higher in adult squids than in juveniles because they fed on prey at higher trophic levels. In conclusion, this study indicates that feeding habits of I. coindetii vary seasonally and ontogenetically. These feeding variations may be associated with trophic competence scenarios based on size, and also with the availability and abundance of prey throughout the year, J.N. was funded by ESFRI LifeWatch project. M.A.-P. was supported by a predoctoral contract of the FPI program (Spanish Ministry of Economy and Competitiveness)

Special issue Future of oceanic animals in a changing ocean.-- This study is a contribution to the project ECOTRANS (CTM2011-26333, MINECO, Spain).-- 9 pages, 3 figures, 4 tables, Small and medium pelagic fishes play a central role in marine food webs by transferring energy from plankton to top predators. In this study, direct calorimetry was used to analyze the energy density of seven pelagic species collected over four seasons from the western Mediterranean Sea: anchovy Engraulis encrasicolus, sardine Sardina pilchardus, round sardinella Sardinella aurita, horse mackerels Trachurus trachurus and T. mediterraneus, and mackerels Scomber scombrus and S. colias. Inter-specific differences in energy density were linked to spawning period, energy allocation strategies for reproduction and growth, and feeding ecologies. Energy density of each species varied over time, with the exception of S. colias, likely due to its high energetic requirements related to migration throughout the year. In general, higher energy density was observed in spring for all species, regardless of their breeding strategy, probably as a consequence of the late-winter phytoplankton bloom. These results provide new insights into the temporal availability of energy in the pelagic ecosystem of the Mediterranean Sea, which are pivotal for understanding how the population dynamics of small and medium pelagic fishes and their predators may respond to environmental changes and fishing impacts. In addition, the differences found in energy density between species highlighted the importance of using species specific energy-values in ecosystem assessment tools such as bioenergetic and food web models, M.A.-P. was supported by a predoctoral contract of the FPI program (BES-2012–054267, Spanish Ministry of Economy and Competitiveness). J.N. was supported by the Andalucía Talent Hub Program (Andalusian Knowledge Agency, European Marie Skłodowska-Curie actions – 267226). M.C. was partially funded by the European Commission through the Marie Curie Career Integration Grant Fellowships – PCIG10-GA-2011-303534 - to the BIOWEB project

5 pages, 2 figures, 1 table, During the past decade, parasites have been considered important components of their ecosystems since they can modify food-web structures and functioning. One constraint to the inclusion of parasites in food-web models is the scarcity of available information on their feeding habits and host–parasite relationships. The stable isotope approach is suggested as a useful methodology to determine the trophic position and feeding habits of parasites. However, the isotopic approach is limited by the lack of information on the isotopic discrimination (ID) values of parasites, which is pivotal to avoiding the biased interpretation of isotopic results. In the present study we aimed to provide the first ID values of δ15N and δ13C between the gyrocotylidean tapeworm Gyrocotyle urna and its definitive host, the holocephalan Chimaera monstrosa. We also test the effect of host body size (body length and body mass) and sex of the host on the ID values. Finally, we illustrate how the trophic relationships of the fish host C. monstrosa and the tapeworm G. urna could vary relative to ID values. Similar to other studies with parasites, the ID values of the parasite–host system were negative for both isotopic values of N (Δδ15N = − 3.33 ± 0.63‰) and C (Δδ13C = − 1.32 ± 0.65‰), independent of the sex and size of the host. By comparing the specific ID obtained here with ID from other studies, we illustrate the importance of using specific ID in parasite–host systems to avoid potential errors in the interpretation of the results when surrogate values from similar systems or organisms are used, J.N. and M.C. were supported by research contracts of the Juan de la Cierva program and Ramon y Cajal (Spanish Ministry of Economy and Competitiveness), respectively

9 pages, 5 figures, 4 tables, Ecological knowledge of food web interactions within pelagic marine communities is often limited, impairing our capabilities to manage these ecologically and economically important marine fish species. Here we used stable isotope analyses to investigate trophic interactions in the pelagic ecosystem of the northwestern Mediterranean Sea during 2012 and 2013. Our results suggest that European sardine, Sardina pilchardus, and anchovy, Engraulis encrasicolus, are consumers located at relatively low levels of the pelagic food web. Unexpectedly, the round sardinella, Sardinella aurita, appeared to be located at a higher trophic level than the other small pelagic fish species, although previous studies found similarity in their diets. Isotope data suggested that trophic niches of species within the genera Trachurus spp. and Scomber spp., were distinct. Atlantic bonito Sarda sarda, European hake Merluccius merluccius and European squid Loligo vulgaris, appeared to feed at higher trophic levels than other species. Despite some intraspecific seasonal variability for some species, community trophic structure appeared relatively stable through the year. These data provide an important step for developing models of food web dynamics in the northwestern Mediterranean Sea, M.A.-P. was supported by a predoctoral contract of the FPI program and a Short-Stay FPI grant (BES-2012-054267, Spanish Ministry of Economy and Competitiveness). J.N. was supported by the Andalucía Talent Hub Program launched by the Andalusian Knowledge Agency. M.C. was partially funded by the European Commission through the Marie Curie Career Integration Grant Fellowships – PCIG10-GA-2011-303534 – to the BIOWEB project. This study is a contribution to the project ECOTRANS (CTM2011-26333, Spanish Ministry of Economy and Competitiveness, Spain).

9 pages, 4 figures, 4 tables, 1 appendix supplementary data https://dx.doi.org/10.1016/j.ecss.2016.03.007.-- This study is a contribution to the project ECOTRANS (CTM2011-26333, Spanish Ministry of Economy and Competiveness, Spain) and to the Master's thesis of NL, The study of the feeding ecology of marine organisms is crucial to understanding their ecological roles and advancing our knowledge of marine ecosystem functioning. The aim of this study was to analyse the trophic ecology of two demersal predator species, black anglerfish (Lophius budegassa) and white anglerfish (L. piscatorius), in the northwestern Mediterranean Sea. Both species are important in the study area due to their high abundance and economic value, but information about their feeding behaviour is scarce. Here, we described the diet composition and ecological role of these two species, investigating whether trophic segregation exists between them and amongst fish of different sizes. In addition, by using experimental survey data we described the spatial distribution of both species to help us interpret trophic behaviour patterns. We gathered samples of two different sizes (small individuals of a total length, JN was supported by the Andalucía Talent Hub Program (Andalusian Knowledge Agency, co funded by the European Union's Seventh Framework Program, Marie Skłodowska Curie actions). MC was partially funded by the European Commission through the Marie Curie Career Integration Grant Fellowships – PCIG10-GA-2011-303534 – to the BIOWEB project and by the Spanish National Program Ramon y Cajal. CB and MA-P were supported by predoctoral fellowships of CONICYT-Becas Chile and FPI program of Spanish Ministry of Economy and Competitiveness, respectively.

VI Congreso Ibérico de Ictiología - VI Iberian Congress of Ichthyology (SIBIC2016), celebrado del 21 al 24 de junio de 2016 en Murcia.-- 3 pages, 1 figure

14 pages, 5 figures, 3 tables, supplementary material http://dx.doi.org/10.3354/meps11188, Understanding how marine predators interact is a scientific challenge. In marine ecosystems, segregation in feeding habits has been largely described as a common mechanism to allow the coexistence of several competing marine predators. However, little is known about the feeding ecology of most species of chondrichthyans, which play a pivotal role in the structure of marine food webs worldwide. In this study, we examined the trophic ecology of 3 relatively abundant chondrichthyans coexisting in the Mediterranean Sea: the blackmouth catshark Galeus melastomus, the velvet belly lanternshark Etmopterus spinax and the rabbit fish Chimaera monstrosa. To examine their trophic ecology and interspecific differences in food habits, we combined the analysis of stomach content and stable isotopes. Our results highlighted a trophic segregation between C. monstrosa and the other 2 species. G. melastomus showed a diet composed mainly of cephalopods, while E. spinax preyed mainly on shrimps and C. monstrosa on crabs. Interspecific differences in the trophic niche were likely due to different feeding capabilities and body size. Each species showed different isotopic niche space and trophic level. Specifically, C. monstrosa showed a higher trophic level than E. spinax and G. melastomus. The high trophic levels of the 3 species highlighted their important role as predators in the marine food web. Our results illustrate the utility of using complementary approaches that provide information about the feeding behaviour at short (stomach content) and long-term scales (stable isotopes), which could allow more efficient monitoring of marine food-web changes in the study area, M.A.-P. was supported by a predoctoral fellowship of the FPI program (Spanish Ministry of Economy and Competitiveness). J.N. was supported by a research contract of the Marie Curie GIC project BioWeb. M.C. and J.A. are supported by a post-doctoral contract of the Ramon y Cajal Program (Spanish Ministry of Economy and Competiveness), and M.C. was also supported by BioWeb project. This study is a contribution to the project ECOTRANS (CTM2011-26333, Ministerio de Economía y Competitividad, Spain)