RESUMEN
Environmental DNA (eDNA) is an increasingly useful method for detecting pelagic animals in the ocean but typically requires large water volumes to sample diverse assemblages. Ship-based pelagic sampling programs that could implement eDNA methods generally have restrictive water budgets. Studies that quantify how eDNA methods perform on low water volumes in the ocean are limited, especially in deep-sea habitats with low animal biomass and poorly described species assemblages. Using 12S rRNA and COI gene primers, we quantified assemblages comprised of micronekton, coastal forage fishes, and zooplankton from low volume eDNA seawater samples (n = 436, 380-1800 mL) collected at depths of 0-2200 m in the southern California Current. We compared diversity in eDNA samples to concurrently collected pelagic trawl samples (n = 27), detecting a higher diversity of vertebrate and invertebrate groups in the eDNA samples. Differences in assemblage composition could be explained by variability in size-selectivity among methods and DNA primer suitability across taxonomic groups. The number of reads and amplicon sequences variants (ASVs) did not vary substantially among shallow (<200 m) and deep samples (>600 m), but the proportion of invertebrate ASVs that could be assigned a species-level identification decreased with sampling depth. Using hierarchical clustering, we resolved horizontal and vertical variability in marine animal assemblages from samples characterized by a relatively low diversity of ecologically important species. Low volume eDNA samples will quantify greater taxonomic diversity as reference libraries, especially for deep-dwelling invertebrate species, continue to expand.
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Organismos Acuáticos , Biodiversidad , ADN Ambiental , Animales , ADN Ambiental/genética , ADN Ambiental/análisis , Organismos Acuáticos/genética , Organismos Acuáticos/clasificación , Agua de Mar , Peces/genética , Peces/clasificación , Zooplancton/genética , Zooplancton/clasificación , Ecosistema , Invertebrados/genética , Invertebrados/clasificaciónRESUMEN
Trait-based frameworks are increasingly used for predicting how ecological communities respond to ongoing global change. As species range shifts result in novel encounters between predators and prey, identifying prey 'guilds', based on a suite of shared traits, can distill complex species interactions, and aid in predicting food web dynamics. To support advances in trait-based research in open-ocean systems, we present the Pelagic Species Trait Database, an extensive resource documenting functional traits of 529 pelagic fish and invertebrate species in a single, open-source repository. We synthesized literature sources and online resources, conducted morphometric analysis of species images, as well as laboratory analyses of trawl-captured specimens to collate traits describing 1) habitat use and behavior, 2) morphology, 3) nutritional quality, and 4) population status information. Species in the dataset primarily inhabit the California Current system and broader NE Pacific Ocean, but also includes pelagic species known to be consumed by top ocean predators from other ocean basins. The aim of this dataset is to enhance the use of trait-based approaches in marine ecosystems and for predator populations worldwide.
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Ecosistema , Cadena Alimentaria , Animales , Peces , Biología Marina , Océano PacíficoRESUMEN
The water column of the deep ocean is dark, cold, low in food, and under crushing pressures, yet it is full of diverse life. Due to its enormous volume, this mesopelagic zone is home to some of the most abundant animals on the planet. Rather than struggling to survive, they thrive-owing to a broad set of adaptations for feeding, behavior, and physiology. Our understanding of these adaptations is constrained by the tools available for exploring the deep sea, but this tool kit is expanding along with technological advances. Each time we apply a new method to the depths, we gain surprising insights about genetics, ecology, behavior, physiology, diversity, and the dynamics of change. These discoveries show structure within the seemingly uniform habitat, limits to the seemingly inexhaustible resources, and vulnerability in the seemingly impervious environment. To understand midwater ecology, we need to reimagine the rules that govern terrestrial ecosystems. By spending more time at depth-with whatever tools are available-we can fill the knowledge gaps and better link ecology to the environment throughout the water column.
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Ecología , Ecosistema , Animales , Agua , BiodiversidadRESUMEN
Pelagic predators are effective biological samplers of midtrophic taxa and are especially useful in deep-sea habitats where relatively mobile taxa frequently avoid observation with conventional methods. We examined specimens sampled from the stomachs of longnose lancetfish, Alepisaurus ferox, to describe the diets and foraging behaviors of three common, but poorly known deep-sea fishes: the hammerjaw (Omosudis lowii, n = 79, 0.3-92 g), juvenile common fangtooth (Anoplogaster cornuta, n = 91, 0.6-22 g), and juvenile Al. ferox (n = 138, 0.3-744 g). Diet overlap among the three species was high, with five shared prey families accounting for 63 ± 11% of the total prey mass per species. However, distinct differences in foraging strategies and prey sizes were evident. Resource partitioning was greatest between An. cornuta that specialized on small (mean = 0.13 ± 0.11 g), shallow-living hyperiid amphipods and O. lowii that specialized on large (mean = 0.97 ± 0.45 g), deep-dwelling hatchetfishes. Juvenile Al. ferox foraged on a high diversity of prey from both shallow and deep habitats. We describe the foraging ecologies of three midtrophic fish competitors and demonstrate the potential for biological samplers to improve our understanding of deep-sea food webs.
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Ecología , Ecosistema , Humanos , Animales , Cadena Alimentaria , Peces , Dieta , Conducta PredatoriaRESUMEN
Long-term biological time series that monitor ecosystems across the ocean's full water column are extremely rare. As a result, classic paradigms are yet to be tested. One such paradigm is that variations in coastal upwelling drive changes in marine ecosystems throughout the water column. We examine this hypothesis by using data from three multidecadal time series spanning surface (0 m), midwater (200 to 1,000 m), and benthic (~4,000 m) habitats in the central California Current Upwelling System. Data include microscopic counts of surface plankton, video quantification of midwater animals, and imaging of benthic seafloor invertebrates. Taxon-specific plankton biomass and midwater and benthic animal densities were separately analyzed with principal component analysis. Within each community, the first mode of variability corresponds to most taxa increasing and decreasing over time, capturing seasonal surface blooms and lower-frequency midwater and benthic variability. When compared to local wind-driven upwelling variability, each community correlates to changes in upwelling damped over distinct timescales. This suggests that periods of high upwelling favor increase in organism biomass or density from the surface ocean through the midwater down to the abyssal seafloor. These connections most likely occur directly via changes in primary production and vertical carbon flux, and to a lesser extent indirectly via other oceanic changes. The timescales over which species respond to upwelling are taxon-specific and are likely linked to the longevity of phytoplankton blooms (surface) and of animal life (midwater and benthos), which dictate how long upwelling-driven changes persist within each community.
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Ecosistema , Invertebrados , Animales , Océanos y Mares , Biomasa , Plancton , AguaRESUMEN
INTRODUCTION: Intravascular ultrasound (IVUS) is recommended in the use of left main stem (LMS) percutaneous coronary intervention (PCI). Since the LMS diameter is usually larger than other coronary arteries, a new generation everolimus drug-eluting stent (DES), Synergy Megatron DES (Boston Scientific) has better axial and radial strength allowing more post implant overexpansion and consequently better suited for LMS lesions. We performed a study to evaluate the clinical outcomes of PCI using 1) an improved IVUS protocol with optimisation targets and 2) the use of Megatron stents. MATERIALS AND METHODS: This was a study involving LMS PCI coronary lesions using the Synergy Megatron DES. An IVUS protocol using predefined optimisation targets to evaluate for stent malapposition, longitudinal stent deformation, optimal stent expansion >90% of reference lumen and appropriate distal landing zone was used in all cases. The primary end-point was procedural success, defined by successful stent implantation with <30% residual stenosis. The secondary end-point was in-hospital and 30-day major adverse cardiovascular event (MACE). RESULTS: Eight patients with significant LMS stenosis were successfully treated with the Megatron stent. The primary end-point was achieved in all patients. There were no cases of stent malapposition or longitudinal stent deformation, one case did not have optimal LMS stent expansion and one case did not have an appropriate distal landing zone. IVUS optimisation criteria were met in 6 (75%) cases. There were no complications of coronary dissection, slow or no reflow, stent thrombosis or vessel perforation. None of the patients suffered in-hospital or 30-day MACE. The average LMS MLD at baseline was 2.1 ± 0.1mm and the post-PCI LMS MLD was 4.0 ± 0.5mm, with a significant acute luminal gain of 1.9 ± 0.7mm (p<0.01). A post-PCI MSA of 17 ± 3.9 mm2 was numerically superior compared to those documented in other LMS PCI trials. CONCLUSION: This study demonstrates low rates of shortterm major adverse cardiovascular events among patients with LMS PCI using the Megatron stents. It highlights the usefulness of IVUS-guided optimisation in LMS PCI. With the use of intravascular imaging, the new generation stent technology can improve the treatment of large proximal vessels and PCI of LMS lesions.
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Enfermedad de la Arteria Coronaria , Stents Liberadores de Fármacos , Intervención Coronaria Percutánea , Humanos , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/cirugía , Everolimus , Intervención Coronaria Percutánea/efectos adversos , Angiografía Coronaria , Constricción Patológica/etiología , Resultado del Tratamiento , Ultrasonografía Intervencional/métodos , AngioplastiaRESUMEN
INTRODUCTION: Coronary artery calcification can lead to suboptimal results when performing coronary angioplasty with conventional techniques. The presence of severe coronary artery calcium increases the complications of percutaneous coronary intervention as it may impede stent delivery and optimal stent expansion. The purpose of this study was to determine the procedural success and safety of orbital atherectomy (OA) in calcified lesions. MATERIALS AND METHODS: This was a prospective single-centre study regarding the utility of OA in the treatment of calcified coronaries. Intravascular ultrasound (IVUS) or optical coherence tomography (OCT) was used in all cases to characterise the severity of calcium pre-procedure, guide vessel sizing and assess procedural success. The primary endpoint was procedural success, defined by successful stent implantation following OA treatment. The secondary endpoint was in-hospital and 30-day major adverse cardiovascular event (MACE). RESULTS: Ten patients with severely calcified lesions were successfully treated with OA. The primary endpoint was achieved in all patients. All of the lesions were severely calcified with concentric calcium. None of the patients suffered in-hospital or 30-day MACE. The average minimal luminal diameter at baseline was 1.7 ± 0.3 mm and the post- PCI luminal diameter was 3.0 ± 0.3 mm, with a significant luminal gain of 1.3 ± 0.3 mm (p < 0.01). Slow flow during procedure occurred in 2 (20%) cases and dissection occurred in 1 (10%) case during procedure. These were successfully treated with stent delivery to achieve TIMI III flow. There were no cases of stent thrombosis or vessel perforation. CONCLUSION: Our experience demonstrates the feasibility and safety of OA in the management of calcified coronary stenosis. Intravascular imaging is an important adjunct to the use of OA to assess the severity of calcified coronary lesions, success of OA treatment and to aid sizing of the vessel for stent implantation. OA is an effective treatment approach to disrupt coronary calcification, facilitating stent implantation with optimal results. It is a safe procedure with good success rate and low rate of complications.
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Aterectomía Coronaria , Enfermedad de la Arteria Coronaria , Intervención Coronaria Percutánea , Calcificación Vascular , Humanos , Intervención Coronaria Percutánea/efectos adversos , Aterectomía Coronaria/efectos adversos , Aterectomía Coronaria/métodos , Estudios Prospectivos , Calcio , Calcificación Vascular/diagnóstico por imagen , Calcificación Vascular/cirugía , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/cirugía , Aterectomía , Resultado del Tratamiento , Índice de Severidad de la EnfermedadRESUMEN
Marine debris is now a ubiquitous component of the Anthropocene global ocean. Plastic ingestion by marine wildlife was first reported in the 1960s and since that time, roughly one thousand marine species have been reported to consume this debris. This study focuses on plastic ingestion by marine invertebrates and vertebrates in the North Pacific Ocean. Specifically, we reviewed the scientific literature to assess the scope of the problem, identified key bioindicator species, and proposed guidelines for future monitoring of plastic debris in North Pacific marine ecosystems. Our meta-analysis confirmed that the North Pacific is among the most polluted ocean regions globally; roughly half of all fish and seabird specimens and more than three-quarters of sea turtles and bivalve specimens examined in this region had consumed plastic. While there are not enough standardized data to assess if these ingestion rates are changing, sampling standardization and reporting of methods are improving over time. Using a rubric-evaluation approach, we evaluated 352 species for their potential to serve as bioindicators of the prevalence of plastic pollution in the North Pacific. This analysis revealed a suite of 12 bioindicator species candidates which sample a variety of ecosystem components and cover a wide range of plastic size classes. Thus, we contend that these bioindicator candidates provide a key foundation for developing a comprehensive plastic monitoring program in the region. To enhance the utility of these bioindicators, we developed a framework for standardized data collection to minimize methodological variability across different studies and to facilitate the assessment of temporal trends over space and time. Tracking plastic ingestion by these bioindicators will help to assess the effectiveness of mitigation actions in the region, a critical step to evaluate progress towards sustainability and improved ocean health in the 21st century.
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Biomarcadores Ambientales , Plásticos , Animales , Ingestión de Alimentos , Ecosistema , Monitoreo del Ambiente , Océano Pacífico , Especies Centinela , ResiduosRESUMEN
INTRODUCTION: Coronary artery calcification can lead to suboptimal results when performing coronary angioplasty with conventional techniques. Shockwave intravascular lithotripsy (IVL) has recently been introduced as a new modality to treat heavily calcified coronary arteries. The purpose of this study was to determine the procedural success and safety of IVL in calcified lesions. MATERIALS AND METHODS: This was a prospective single-centre study regarding the utility of IVL in treatment of calcified coronary arteries. Intravascular ultrasound (IVUS) was used in all cases to characterise the lesions pre procedure and to assess procedural success post procedure. The primary end point was procedural success, defined by IVL treatment and successful stent implantation. The secondary end point was in-hospital and 30-day major adverse cardiovascular event (MACE). RESULTS: Five patients with severely calcified lesions were successfully treated with IVL. The primary end point was achieved in all patients. All of the lesions were severely calcified with concentric calcium. Multiple calcium fractures were identified on IVUS after IVL in all cases. None of the patients suffered in-hospital or 30-day MACE. The average diameter stenosis at baseline was 1.8±0.4mm and the post PCI diameter stenosis was 2.9±0.1mm, with significant acute luminal gain of 1.2±0.3mm (p<0.01). There were no complications of coronary dissection, slow or no reflow, stent thrombosis, or vessel perforation. CONCLUSION: Our initial experience demonstrates the feasibility and safety of IVL in the management of calcified coronary stenosis. The shockwave IVL is an effective treatment approach to disrupt coronary calcification, facilitating stent implantation with optimal results. It is a safe procedure with a good success rate and low rate of complications.
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Enfermedad de la Arteria Coronaria , Litotricia , Intervención Coronaria Percutánea , Calcificación Vascular , Calcio , Constricción Patológica/etiología , Constricción Patológica/terapia , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/terapia , Humanos , Litotricia/efectos adversos , Litotricia/métodos , Estudios Prospectivos , Sistema de Registros , Resultado del Tratamiento , Calcificación Vascular/diagnóstico por imagen , Calcificación Vascular/etiología , Calcificación Vascular/terapiaRESUMEN
Siphonophores (Cnidaria: Hydrozoa) are abundant and diverse gelatinous predators in open-ocean ecosystems. Due to limited access to the midwater, little is known about the diets of most deep-dwelling gelatinous species, which constrains our understanding of food-web structure and nutrient flow in these vast ecosystems. Visual gut-content methods can rarely identify soft-bodied rapidly-digested prey, while observations from submersibles often overlook small prey items. These methods have been differentially applied to shallow and deep siphonophore taxa, confounding habitat and methodological biases. DNA metabarcoding can be used to assess both shallow and deep species' diets under a common methodological framework, since it can detect both small and gelatinous prey. We (1) further characterized the diets of open-ocean siphonophores using DNA metabarcoding, (2) compared the prey detected by visual and molecular methods to evaluate their technical biases, and (3) evaluated tentacle-based predictions of diet. To do this, we performed DNA metabarcoding analyses on the gut contents of 39 siphonophore species across depths to describe their diets, using six barcode regions along the 18S gene. Taxonomic identifications were assigned using public databases combined with local zooplankton sequences. We identified 55 unique prey items, including crustaceans, gelatinous animals, and fish across 47 siphonophore specimens in 24 species. We reported 29 novel predator-prey interactions, among them the first insights into the diets of nine siphonophore species, many of which were congruent with the dietary predictions based on tentilla morphology. Our analyses detected both small and gelatinous prey taxa underrepresented by visual methods in species from both shallow and deep habitats, indicating that siphonophores play similar trophic roles across depth habitats. We also reveal hidden links between siphonophores and filter-feeders near the base of the food web. This study expands our understanding of the ecological roles of siphonophores in the open ocean, their trophic roles within the 'jelly-web', and the importance of their diversity for nutrient flow and ecosystem functioning. Understanding these inconspicuous yet ubiquitous predator-prey interactions is critical to predict the impacts of climate change, overfishing, and conservation policies on oceanic ecosystems.
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Hidrozoos , Animales , Conservación de los Recursos Naturales , Código de Barras del ADN Taxonómico , Dieta , Ecosistema , Explotaciones Pesqueras , Cadena Alimentaria , Hidrozoos/anatomía & histología , Conducta PredatoriaRESUMEN
BACKGROUND: Sepsis is an important global healthcare problem that is a key challenge faced by healthcare professionals face worldwide. One key effort aimed at reducing the global burden of sepsis is educating healthcare professionals about early identification and management of sepsis. AIM: To provide a comprehensive evaluation of sepsis education among healthcare professionals and students. METHODS: Six databases (PubMed, CINAHL, Embase, MEDLINE, Cochrane Central Register of Controlled Trials, and Scopus) were searched. We included studies that described and evaluated any form of education or training on sepsis delivered to healthcare professionals and students. Study outcomes were summarized according to the adapted Kirkpatrick model of training evaluation. RESULTS: Thirty-two studies were included in the review. The learning contents were reported to be in accordance with the Surviving Sepsis Campaign guidelines. Seven studies included the topic of interprofessional teamwork and communication in their sepsis education content. Most educational programmes were effective and reported positive effects on immediate knowledge outcomes. Interventions that were delivered through an active learning approach such as simulation and game-based learning generally produced greater gains than didactic teaching. Improvements in patient care processes and patient outcomes were associated with the concomitant existence or implementation of a hospital sepsis care bundle. CONCLUSION: Incorporating active learning strategies into sepsis education interventions has the potential to improve learners' long-term outcomes. In addition, sepsis education and a protocol-based sepsis care bundle act in synergy to augment greater improvements in care processes and patient benefits.
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Personal de Salud , Sepsis , Competencia Clínica , Atención a la Salud , Personal de Salud/educación , Humanos , Sepsis/diagnóstico , Sepsis/terapia , EstudiantesRESUMEN
Coronary artery calcification is a pathological deposition of calcium in the intimal and medial layer of the arterial wall. Shockwave intravascular lithotripsy (IVL) has evolved as a new modality to treat heavily calcified coronary arteries. IVL involves using a percutaneous device to produce acoustic pressure waves resulting in the delivery of sufficient energy to break up superficial and deep calcium deposits. We present a case where highly dense coronary calcium was successfully treated with intravascular ultrasound (IVUS) guided coronary angioplasty and IVL treatment. IVUS demonstrated heavy calcification at the proximal LAD with a 360° calcium arc. Post procedure, IVUS demonstrated multiple fractures of coronary calcium. Stent deployment was done successfully with good stent strut apposition. There was no procedure related complication. The case demonstrates an example where IVL is an important adjunctive tool in the cardiac catheterization laboratory for lesion preparation and optimal percutaneous coronary intervention.
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Litotricia , Calcificación Vascular , Vasos Coronarios/diagnóstico por imagen , Humanos , Litotricia/métodos , Resultado del Tratamiento , Ultrasonografía Intervencional , Calcificación Vascular/cirugía , Calcificación Vascular/terapiaRESUMEN
AIM: Early-life environmental exposure, which has important implications in the pathogenesis of inflammatory bowel disease (IBD), is not well understood in Asian children. We examined environmental factors prior to the development of childhood IBD in a Southeast Asian population. METHODS: We conducted a case control study in IBD diagnosed before 18 years of age and controls matched by gender, age and ethnicity. A questionnaire recording medical, family, dietary and social histories, home environment, childhood diseases and immunisation status was used. RESULTS: In a multivariate analysis involving 70 children with IBD (Crohn's disease (CD) = 38; ulcerative colitis (UC) = 32) and 140 controls, childhood acute gastroenteritis (odds ratio (OR): IBD 6.9; CD 7.8; UC 5.8) and excessive antibiotic usage in early childhood (OR: IBD 5.3; CD 4.2; UC 4.8) were significantly associated with IBD, CD and UC. Having a fish or turtle aquarium (OR 6.0), major stressful life events (OR 5.6) and attending the same school concurrently with a sibling (OR 2.9) were significant risk factors for IBD. Duration of breastfeeding >6 months (OR: IBD 0.4; UC 0.2) and safe water consumption (OR: IBD 0.2; UC 0.2) reduced the odds of having IBD and UC, respectively. Being vaccinated for rotavirus reduced the odds of developing IBD (OR 0.1). CONCLUSIONS: Several risk and protective factors were identified in this environmental risk study in Southeast Asian children with IBD. This knowledge has important implications in understanding disease aetiology and future prevention strategies to reduce the development of IBD in Southeast Asian children.
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Colitis Ulcerosa , Enfermedad de Crohn , Enfermedades Inflamatorias del Intestino , Animales , Estudios de Casos y Controles , Preescolar , Enfermedad Crónica , Humanos , Enfermedades Inflamatorias del Intestino/epidemiología , Enfermedades Inflamatorias del Intestino/etiología , Factores de RiesgoRESUMEN
Hypertension is a significant cardiovascular risk factor. Although the mainstay of treatment remains medication, there are a number of patients with resistant hypertension who have elevated blood pressure despite multiple medications. Failure to achieve adequately controlled blood pressures despite medications put these patients at risk of target organ damage and significant morbidity from hypertension. The renal denervation procedure involves the application of radiofrequency energy or ultrasound at the renal arteries to modulate afferent and efferent sympathetic renal activity. This treatment potentially can improve blood pressure control in patients who have resistant hypertension despite medication. This article presents two case reports of successful treatment of resistant hypertension using radiofrequency renal sympathetic denervation (RDN) at a private medical centre using the latest Spyral catheter. We also reviewed the latest RDN trials to give some insights into this procedure.
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Ablación por Catéter , Hipertensión , Presión Sanguínea , Humanos , Hipertensión/cirugía , Arteria Renal/cirugía , Simpatectomía , Resultado del TratamientoRESUMEN
Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (δ15 N) are primarily used to estimate trophic position while carbon isotopes (δ13 C) describe habitat associations and feeding pathways. Models of both δ15 N and δ13 C values and their associated variance can be used to estimate likely dietary contributions and niche width and provide inferences about consumer movement and migration. Stable isotope data have added utility when used in combination with other empirical data sets (e.g., stomach content, movement tracking, bioregionalization, contaminant, or fisheries data) and are increasingly relied upon in food web and ecosystem models. While numerous regional studies publish tables of mean δ15 N and δ13 C values, limited individual records have been made available for wider use. Such a deficiency has impeded full utility of the data, which otherwise would facilitate identification of macroscale patterns. The data provided here consist of 4,498 records of individuals of three tuna species, Thunnus alalunga, T. obesus, and T. albacares sampled from all major ocean basins from 2000 to 2015. For each individual tuna, we provide a record of the following: species name, sampling date, sampling location, tuna length, muscle bulk and baseline corrected δ15 N values, and muscle bulk and, where available, lipid corrected δ13 C values. We provide these individual records to support comparative studies and more robust modeling projects seeking to improve understanding of complex marine ecosystem dynamics and their responses to a changing environment. There are no copyright restrictions for research and/or teaching purposes. Users are requested to acknowledge their use of the data in publications, research proposals, websites, and other outlets following the citation instructions in Class III, Section B.
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Endoscopía Capsular/métodos , Endoscopía Gastrointestinal/métodos , Neoplasias Gastrointestinales/diagnóstico , Tumores del Estroma Gastrointestinal/diagnóstico , Intestino Delgado/patología , Anciano , Neoplasias Gastrointestinales/cirugía , Tumores del Estroma Gastrointestinal/cirugía , Humanos , Intestino Delgado/cirugía , Masculino , PronósticoRESUMEN
Considerable uncertainty remains over how increasing atmospheric CO2 and anthropogenic climate changes are affecting open-ocean marine ecosystems from phytoplankton to top predators. Biological time series data are thus urgently needed for the world's oceans. Here, we use the carbon stable isotope composition of tuna to provide a first insight into the existence of global trends in complex ecosystem dynamics and changes in the oceanic carbon cycle. From 2000 to 2015, considerable declines in δ13 C values of 0.8-2.5 were observed across three tuna species sampled globally, with more substantial changes in the Pacific Ocean compared to the Atlantic and Indian Oceans. Tuna recorded not only the Suess effect, that is, fossil fuel-derived and isotopically light carbon being incorporated into marine ecosystems, but also recorded profound changes at the base of marine food webs. We suggest a global shift in phytoplankton community structure, for example, a reduction in 13 C-rich phytoplankton such as diatoms, and/or a change in phytoplankton physiology during this period, although this does not rule out other concomitant changes at higher levels in the food webs. Our study establishes tuna δ13 C values as a candidate essential ocean variable to assess complex ecosystem responses to climate change at regional to global scales and over decadal timescales. Finally, this time series will be invaluable in calibrating and validating global earth system models to project changes in marine biota.
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Fitoplancton , Atún , Animales , Isótopos de Carbono , Ecosistema , Océano Índico , Océanos y Mares , Océano PacíficoRESUMEN
Many species of micronekton perform diel vertical migrations (DVMs), which ultimately contributes to carbon export to the deep sea. However, not all micronekton species perform DVM, and the nonmigrators, which are often understudied, have different energetic requirements that might be reflected in their trophic ecology. We analyze bulk tissue and whole animal stable nitrogen isotopic compositions (δ 15N values) of micronekton species collected seasonally between 0 and 1250 m depth to explore differences in the trophic ecology of vertically migrating and nonmigrating micronekton in the central North Pacific. Nonmigrating species exhibit depth-related increases in δ 15N values mirroring their main prey, zooplankton. Higher variance in δ 15N values of bathypelagic species points to the increasing reliance of deeper dwelling micronekton on microbially reworked, very small suspended particles. Migrators have higher δ 15N values than nonmigrators inhabiting the epipelagic zone, suggesting the consumption of material during the day at depth, not only at night when they migrate closer to the surface. Migrating species also appear to eat larger prey and exhibit a higher range of variation in δ 15N values seasonally than nonmigrators, likely because of their higher energy needs. The dependence on material at depth enriched in 15N relative to surface particles is higher in migratory fish that ascend only to the lower epipelagic zone. Our results confirm that stark differences in the food habits and dietary sources of micronekton species are driven by vertical migrations.