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  1. Article ; Online: Foraging patterns and trophic interactions of sympatric populations of young-of-the-year bluefin and skipjack tunas in the East Atlantic (Gulf of Cadiz)

    Varela, José Luis / Abascal, Francisco J. / Medina, Antonio

    Regional Studies in Marine Science. 2023 Apr. 17, p.102961-

    2023  , Page(s) 102961–

    Abstract: Foraging patterns and trophic interactions of young-of-the-year Atlantic bluefin (Thunnus thynnus, ABFT) and skipjack (Katsuwonus pelamis, SKJ) tunas co-occurring in coastal waters off the Gulf of Cadiz (GoC, East Atlantic Ocean) were investigated using ... ...

    Abstract Foraging patterns and trophic interactions of young-of-the-year Atlantic bluefin (Thunnus thynnus, ABFT) and skipjack (Katsuwonus pelamis, SKJ) tunas co-occurring in coastal waters off the Gulf of Cadiz (GoC, East Atlantic Ocean) were investigated using stomach content and stable isotope analyses. Both species fed primarily on epipelagic fishes such as European anchovy (Engraulis encrasicholus), sardine (Sardina pilchardus) and Atlantic chub mackerel (Scomber colias). In SKJ, a positive correlation was found between δ15N values of muscle and liver and straight fork length (SFL). Differences in liver δ15N values suggest that ABFT were recently foraging at higher trophic levels than SKJ. Isotopic niche areas estimated by standard ellipse areas (SEAC) and kernel utilization density (KUD) analyses showed a broader niche for SKJ compared to ABFT, indicating a more diverse diet in the former species. There was no significant niche overlap between both tuna species, suggesting trophic niche partitioning and reduced competition for the resources.
    Keywords Engraulis encrasicolus ; Katsuwonus pelamis ; Sardina pilchardus ; Scomber colias ; Thunnus thynnus ; diet ; liver ; marine science ; muscles ; sardines ; stable isotopes ; stomach ; sympatry ; tuna ; Atlantic Ocean ; Trophic biology ; Stomach content analysis ; Stable isotope analysis ; δ15N ; δ13C
    Language English
    Dates of publication 2023-0417
    Publishing place Elsevier B.V.
    Document type Article ; Online
    Note Pre-press version ; Use and reproduction
    ISSN 2352-4855
    DOI 10.1016/j.rsma.2023.102961
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: The gills and skin microbiota of five pelagic fish species from the Atlantic Ocean.

    Varela, José Luis / Nikouli, Eleni / Medina, Antonio / Papaspyrou, Sokratis / Kormas, Konstantinos

    International microbiology : the official journal of the Spanish Society for Microbiology

    2024  

    Abstract: The gills and skin microbiota and microbiome of wild fish remain far more under-investigated compared to that of farmed fish species, despite that these animal-microbe interactions hold the same ecophysiological roles in both cases. In this study, the ... ...

    Abstract The gills and skin microbiota and microbiome of wild fish remain far more under-investigated compared to that of farmed fish species, despite that these animal-microbe interactions hold the same ecophysiological roles in both cases. In this study, the gills and skin bacterial microbiota profiles and their presumptive bacterial metabolisms were investigated in five open-sea fishes: bullet tuna (Auxis sp.), common dolphinfish (Coryphaena hippurus), Atlantic little tunny (Euthynnus alletteratus), Atlantic bonito (Sarda sarda) and Atlantic white marlin (Kajikia albida). Gills and skin tissues were collected from two to three individuals per species, from specimens caught by recreational trolling during summer of 2019, and their bacterial 16S rRNA gene diversity was analysed by high-throughput sequencing. The gills bacterial communities among the five species were clearly different but not the skin bacterial microbiota. The dominant operational taxonomic units belonged to the Moraxellaceae, Pseudomonadaceae, Rhodobacteraceae, Staphylococcaceae and Vibrionaceae families. Despite the differences in taxonomic composition, the presumptive bacterial metabolisms between the gills and skin of the five fishes investigated here were ≥ 94% similar and were dominated by basic metabolism, most likely reflecting the continuous exposure of these tissues in the surrounding seawater.
    Language English
    Publishing date 2024-05-13
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 1454951-7
    ISSN 1618-1905 ; 1139-6709
    ISSN (online) 1618-1905
    ISSN 1139-6709
    DOI 10.1007/s10123-024-00524-8
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Spatial- and size-related shifts in feeding habits of the common dolphinfish (Coryphaena hippurus) in the Southeast Pacific Ocean

    Pincay-Espinoza, Jonathan E. / Varela, José L.

    Environmental biology of fishes. 2022 Feb., v. 105, no. 2

    2022  

    Abstract: Feeding habits of common dolphinfish (Coryphaena hippurus) were investigated in the Southeast Pacific Ocean using stomach content analysis. Stomachs were collected from 1506 individuals ranging between 18 and 187 cm in fork length. The fish were caught ... ...

    Abstract Feeding habits of common dolphinfish (Coryphaena hippurus) were investigated in the Southeast Pacific Ocean using stomach content analysis. Stomachs were collected from 1506 individuals ranging between 18 and 187 cm in fork length. The fish were caught by longliner boats in 2009–2017. Based on percentage of wet weight (%Wᵢ), percentage of number (%Nᵢ), and frequency of occurrence (%Oᵢ), flyingfishes were the predominant prey, followed by the cephalopods jumbo squid (Dosidicus gigas) and argonaut (Argonauta spp.). Permutational multivariate analysis of variance (PERMANOVA) detected significant differences between zones (p < 0.001). PERMANOVA also revealed two size-related shifts in feeding habits to occur at FL ~ 80 cm and FL ~ 110 cm (p < 0.001). Cumulative prey curves did not reach an asymptote in any of the zones and size classes, which may be attributed to the fine taxonomic resolution used. Spatial variations in daily meal ranged between 296.3 and 438.9 g day⁻¹, corresponding to daily ration of 6.1–8.2% body mass BM day⁻¹. Otherwise, size-related variations in both DM and DR were observed. Thus, while daily food intake increased with size from 177.3 for the smallest fish (LF < 80 cm) to 496.7 g day⁻¹ for the largest ones (LF ≥ 110 cm), DR decreased from 13.0 ± 22.1 to 3.7 ± 0.7 BM day⁻¹. The present results contribute to improve the understanding of dolphinfish feeding habits in the Southeast Pacific Ocean.
    Keywords Coryphaena hippurus ; Dosidicus gigas ; Exocoetidae ; body weight ; fish ; food intake ; multivariate analysis ; stomach ; Pacific Ocean
    Language English
    Dates of publication 2022-02
    Size p. 313-326.
    Publishing place Springer Netherlands
    Document type Article
    ZDB-ID 196790-3
    ISSN 1573-5133 ; 0378-1909
    ISSN (online) 1573-5133
    ISSN 0378-1909
    DOI 10.1007/s10641-022-01231-x
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  4. Article ; Online: Effects of endosperm type and storage length of whole-plant corn silage on nitrogen fraction, fermentation products, zein profile, and starch digestibility.

    Varela, José / Ferraretto, Luiz F / Kaeppler, Shawn M / de León, Natalia

    Journal of dairy science

    2023  Volume 106, Issue 12, Page(s) 8710–8722

    Abstract: Zeins are commercially important proteins found in corn endosperms. The objective of this study was to evaluate the effect of altering zein levels in corn inbred lines carrying endosperm mutations with differential allelic dosage and analyze the effects ... ...

    Abstract Zeins are commercially important proteins found in corn endosperms. The objective of this study was to evaluate the effect of altering zein levels in corn inbred lines carrying endosperm mutations with differential allelic dosage and analyze the effects on the composition, nutritive value, and starch digestibility of whole-plant corn silage (WPCS) at 5 storage lengths. Three inbred lines carrying 3 different endosperm modifiers (opaque-2 [o2], floury-2 [fl2], and soft endosperm-1 [h1]) were pollinated with 2 pollen sources to form pairs of near-isogenic lines with either 2 or 3 doses of the mutant allele for each endosperm modifier. The experiment was designed as a split-plot design with 3 replications. Pollinated genotype was the main plot factor, and storage length was the subplot-level factor. Agronomic precautions were taken to mimic hybrid WPCS to the extent possible. Samples were collected at approximately 30% dry matter (DM) using a forage harvester and ensiled in heat-sealed plastic bags for 0, 30, 60, 120, and 240 d. Thus, the experiment consisted of 30 treatments (6 genotypes × 5 storage lengths) and 90 ensiling units (3 replications per treatment). Measurements included nutrient analysis, including crude protein, soluble crude protein, amylase-treated neutral detergent fiber, acid detergent fiber, lignin, starch, fermentation end products, zein concentration, and in vitro starch digestibility (ivSD). The nutritional profile of the inbred-based silage samples was similar to hybrid values reported in literature. Significant differences were found in fresh (unfermented) sample kernels for endosperm vitreousness and zein profiles between and within isogenic pairs. The o2 homozygous (3 doses of mutant allele) had the highest reduction in vitreousness level (74.5 to 38%) and zein concentration (6.2 to 4.7% of DM) compared with the heterozygous counterpart (2 doses of mutant allele). All genotypes showed significant reduction of total zeins and α-zeins during progressive storage length. In vitro starch digestibility increased with storage length and had significant effects of genotype and storage length but not for genotype by storage length interaction, which suggests that the storage period did not attenuate the difference in ivSD between near-isogenic pairs caused by zeins in WPCS. Both total zeins and α-zeins showed a strong negative correlation with ivSD, which agrees with the general hypothesis that the degradation of zeins increases ruminal starch degradability. Homozygous o2 was the only mutant with significantly higher ivSD compared with the heterozygous version, which suggests that, if all other conditions remain constant in a WPCS systems, substantial reductions in endosperm α-zeins are required to significantly improve ivSD in the silo.
    MeSH term(s) Animals ; Silage/analysis ; Starch/metabolism ; Endosperm/metabolism ; Zea mays/metabolism ; Zein/metabolism ; Fermentation ; Nitrogen/metabolism ; Detergents/metabolism ; Rumen/metabolism ; Digestion
    Chemical Substances Starch (9005-25-8) ; Zein (9010-66-6) ; Nitrogen (N762921K75) ; Detergents
    Language English
    Publishing date 2023-08-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 242499-x
    ISSN 1525-3198 ; 0022-0302
    ISSN (online) 1525-3198
    ISSN 0022-0302
    DOI 10.3168/jds.2023-23382
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Use of artificial intelligence in the detection of the critical view of safety during laparoscopic cholecystectomy.

    Petracchi, Enrique J / Olivieri, Sean E / Varela, Jose / Canullan, Carlos M / Zandalazini, Hugo / Ocampo, Carlos / Quesada, Bernabé M

    Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract

    2024  

    Abstract: Background: This study aimed to evaluate the use of artificial intelligence (AI) to detect the critical view of safety during elective laparoscopic cholecystectomy.: Methods: This was a prospective, observational study evaluating the detection of the ...

    Abstract Background: This study aimed to evaluate the use of artificial intelligence (AI) to detect the critical view of safety during elective laparoscopic cholecystectomy.
    Methods: This was a prospective, observational study evaluating the detection of the critical view of safety with an AI software in a consecutive series of elective laparoscopic cholecystectomies compared with the blinded evaluation of 3 surgeons. The program was created using the digital tools PyCharm (JetBrains), Google Colab Pro (https://colab.google/), and YOLOv8 (Ultralytics).
    Results: A total of 40 consecutive elective laparoscopic cholecystectomies were included in the study. The program was able to detect the critical view of safety in all cases following the experts' blinded opinion.
    Conclusion: In this preliminary experience, an AI software was able to detect the critical view of safety in elective laparoscopic cholecystectomies. Its application during nonelective cases, in which the critical view of safety is harder to achieve, might warrant further studies.
    Language English
    Publishing date 2024-03-18
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2012365-6
    ISSN 1873-4626 ; 1934-3213 ; 1091-255X
    ISSN (online) 1873-4626 ; 1934-3213
    ISSN 1091-255X
    DOI 10.1016/j.gassur.2024.03.018
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Common dolphinfish, Coryphaena hippurus, spawn at their easternmost Atlantic range adjacent to the Mediterranean Sea

    Medina, Antonio / Abascal, Francisco J. / Varela, José L.

    Journal of fish biology. 2020 Aug., v. 97, no. 2

    2020  

    Abstract: This study provides sound evidence of the spawning activity of common dolphinfish (Coryphaena hippurus) in the Gulf of Cadiz (southwest Spain) during summer months. Along with waters off Côte d'Ivoire, this area adjacent to the Mediterranean Sea is the ... ...

    Abstract This study provides sound evidence of the spawning activity of common dolphinfish (Coryphaena hippurus) in the Gulf of Cadiz (southwest Spain) during summer months. Along with waters off Côte d'Ivoire, this area adjacent to the Mediterranean Sea is the easternmost Atlantic spawning ground documented for the species. All the fish analysed (5 males and 15 females) were at spawning stage, except the smallest female (61.5 cm in fork length), which might not have yet reached sexual maturation. The oceanographic conditions during the samplings were similar to those occurring during the peak spawning season in the Gulf of Mexico. The study results are consistent with recent genetic studies indicating differentiation between Mediterranean and Atlantic dolphinfish populations, with the Strait of Gibraltar representing a boundary between two distinct reproductive units. The present results may contribute to improve the understanding of the dynamics of dolphinfish population and the management of eastern Atlantic and Mediterranean stocks.
    Keywords Coryphaena hippurus ; females ; fish ; sexual maturity ; summer ; Cote d'Ivoire ; Gulf of Mexico ; Mediterranean Sea ; Spain ; Strait of Gibraltar
    Language English
    Dates of publication 2020-08
    Size p. 409-415.
    Publishing place Blackwell Publishing Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 410564-3
    ISSN 1095-8649 ; 0022-1112
    ISSN (online) 1095-8649
    ISSN 0022-1112
    DOI 10.1111/jfb.14379
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  7. Article: Seasonal feeding patterns of Atlantic bluefin tuna (Thunnus thynnus) in the Strait of Gibraltar

    Varela, José Luis / Carrera, Irene / Medina, Antonio

    Marine environmental research. 2020 Jan., v. 153

    2020  

    Abstract: The Strait of Gibraltar (SoG) houses a large diversity of marine species including large pelagic animals that use this area as permanent or temporary habitat. In particular, the SoG is home to a population of adult and sub-adult Atlantic bluefin tuna ( ... ...

    Abstract The Strait of Gibraltar (SoG) houses a large diversity of marine species including large pelagic animals that use this area as permanent or temporary habitat. In particular, the SoG is home to a population of adult and sub-adult Atlantic bluefin tuna (Thunnus thynnus) that occurs there for most of the year. To gain further insight into the life history of this ABFT population, seasonal feeding patterns were investigated combining stomach content analysis (SCA) and stable isotopes analysis (SIA) of muscle and liver tissues. Our results reveal seasonal variations in feeding patterns, which are evidenced by a significant shift in the diet composition and the highest food consumption rates that take place in spring, prior to the spawning season. These changes in feeding habits are consistent with the varying energetic needs along the species’ annual biological cycle. The present observations confirm the SoG as an important foraging ground for ABFT resident populations and may have further implications for the management of the resource.
    Keywords Thunnus thynnus ; adults ; animals ; diet ; feeding patterns ; food consumption ; foraging ; habitats ; life history ; liver ; muscles ; seasonal variation ; spawning ; spring ; stable isotopes ; stomach ; tissues ; Strait of Gibraltar
    Language English
    Dates of publication 2020-01
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 1502505-6
    ISSN 1879-0291 ; 0141-1136
    ISSN (online) 1879-0291
    ISSN 0141-1136
    DOI 10.1016/j.marenvres.2019.104811
    Database NAL-Catalogue (AGRICOLA)

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  8. Article ; Online: Common dolphinfish, Coryphaena hippurus, spawn at their easternmost Atlantic range adjacent to the Mediterranean Sea.

    Medina, Antonio / Abascal, Francisco J / Varela, José L

    Journal of fish biology

    2020  Volume 97, Issue 2, Page(s) 409–415

    Abstract: This study provides sound evidence of the spawning activity of common dolphinfish (Coryphaena hippurus) in the Gulf of Cadiz (southwest Spain) during summer months. Along with waters off Côte d'Ivoire, this area adjacent to the Mediterranean Sea is the ... ...

    Abstract This study provides sound evidence of the spawning activity of common dolphinfish (Coryphaena hippurus) in the Gulf of Cadiz (southwest Spain) during summer months. Along with waters off Côte d'Ivoire, this area adjacent to the Mediterranean Sea is the easternmost Atlantic spawning ground documented for the species. All the fish analysed (5 males and 15 females) were at spawning stage, except the smallest female (61.5 cm in fork length), which might not have yet reached sexual maturation. The oceanographic conditions during the samplings were similar to those occurring during the peak spawning season in the Gulf of Mexico. The study results are consistent with recent genetic studies indicating differentiation between Mediterranean and Atlantic dolphinfish populations, with the Strait of Gibraltar representing a boundary between two distinct reproductive units. The present results may contribute to improve the understanding of the dynamics of dolphinfish population and the management of eastern Atlantic and Mediterranean stocks.
    MeSH term(s) Animals ; Atlantic Ocean ; Female ; Male ; Mediterranean Sea ; Perciformes/physiology ; Reproduction ; Seasons ; Sexual Behavior, Animal/physiology ; Spain
    Language English
    Publishing date 2020-06-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 410564-3
    ISSN 1095-8649 ; 0022-1112
    ISSN (online) 1095-8649
    ISSN 0022-1112
    DOI 10.1111/jfb.14379
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Feeding ecology of Atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Saint Lawrence, Canada.

    Varela, José L / Spares, Aaron D / Stokesbury, Michael J W

    Marine environmental research

    2020  Volume 161, Page(s) 105087

    Abstract: Feeding ecology of Atlantic bluefin tuna (ABFT, Thunnus thynnus), from the Gulf of Saint Lawrence, Canada, was assessed by stomach content and stable isotope analyses. Stomachs were collected from 161 individuals averaging 249 ± 20 cm in curved fork ... ...

    Abstract Feeding ecology of Atlantic bluefin tuna (ABFT, Thunnus thynnus), from the Gulf of Saint Lawrence, Canada, was assessed by stomach content and stable isotope analyses. Stomachs were collected from 161 individuals averaging 249 ± 20 cm in curved fork length and 248 ± 64 in round weight. The fish were caught by commercial fishing boats using rod and reel gear during fall 2015-2017. Liver and muscle samples were taken from 133 fish for stable isotope analysis. Atlantic mackerel (Scomber scombrus) was the most abundant prey item in 2015 (%Alimentary index, %AI = 88.94), whereas in 2016 and 2017 the ABFT diet was mainly composed of Atlantic herring (Clupea harengus) (%AI = 56.73 and %AI = 77.23, respectively). PERMANOVA analysis revealed significant differences in the dietary composition between years. δ
    MeSH term(s) Animals ; Canada ; Diet ; Ecology ; Humans ; Isotopes ; Tuna
    Chemical Substances Isotopes
    Language English
    Publishing date 2020-07-25
    Publishing country England
    Document type Journal Article
    ZDB-ID 1502505-6
    ISSN 1879-0291 ; 0141-1136
    ISSN (online) 1879-0291
    ISSN 0141-1136
    DOI 10.1016/j.marenvres.2020.105087
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: An autofluorescence-based survey of late follicular atresia in ovaries of a teleost fish (Thunnus thynnus).

    Medina, Antonio / Magro, Ana / Paullada-Salmerón, José Antonio / Varela, José Luis

    Journal of fish biology

    2021  Volume 99, Issue 3, Page(s) 765–772

    Abstract: In this study, the authors examined late atretic follicles in the ovaries of Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758), at different times of the year using transmitted light and epifluorescence microscopy. Atresia (degeneration and ... ...

    Abstract In this study, the authors examined late atretic follicles in the ovaries of Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758), at different times of the year using transmitted light and epifluorescence microscopy. Atresia (degeneration and resorption of developing ovarian follicles) is a natural process involved in fecundity downregulation in teleosts and is substantially enhanced in stressful conditions. Early (α and β) atretic stages of yolked oocytes have a relatively short duration in seasonally reproducing species, whereas later (γ and δ) atretic follicles (LAF) persist for longer time in the ovary, serving as a sign of previous vitellogenic activity. LAF can thus be used as reliable markers of maturity during non-reproductive periods. Lipofuscin granules accumulate in the cytoplasm of LAF cells as a result of lysosomal digestion of oocyte components. Taking advantage of the well-known autofluorescent properties of lipofuscins, LAF may be identified in unstained histological sections under fluorescence microscopy using appropriate excitation and emission wavelengths. The authors explore in this study the applicability of fluorescence microscopy to provide a fast and effective method to assess late atresia in fishes. This method may be particularly useful to determine sexual maturity in individuals sampled long after the spawning season, where LAF are difficult to detect in standard histological sections. Furthermore, LAF autofluorescence provides a rapid way to quantify late atresia in fishes using image analysis.
    MeSH term(s) Animals ; Female ; Fishes ; Follicular Atresia ; Ovarian Follicle ; Ovary ; Tuna
    Language English
    Publishing date 2021-05-11
    Publishing country England
    Document type Journal Article
    ZDB-ID 410564-3
    ISSN 1095-8649 ; 0022-1112
    ISSN (online) 1095-8649
    ISSN 0022-1112
    DOI 10.1111/jfb.14756
    Database MEDical Literature Analysis and Retrieval System OnLINE

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