Emerging issues in fisheries science by fisheries scientists.

The current epoch in fisheries science has been driven by continual advances in laboratory techniques and  increasingly sophisticated approaches to analysing datasets. We now have the scientific knowledge and tools to proactively identify obstacles to the sustainable management of marine resources. However, in addition to technological advances, there are predicted global environmental changes, each with inherent implications for fisheries. The 2023 symposium of the Fisheries Society of the British Isles called for "open and constructive knowledge exchange between scientists, stakeholders, managers and policymakers" (https://fsbi.org.uk/symposium-2023/), a nexus of collaborative groups best placed to identify issues and solutions. Arguably, the Centre of Environment, Aquaculture and Fisheries Science (Cefas) and their Scientific Advice for Fisheries Management (SAFM) Team sit at the centre of such a network. SAFM regularly engages with managers and stakeholders, undertakes scientific research, provides fisheries advice to the UK government, and are leading experts within the International Council for the Exploration of the Sea (ICES). As such, this paper is an opinion piece, linked to individual authors specialisms, that aims to highlight emerging issues affecting fisheries and suggest where research efforts could be focused that contribute to sustainable fisheries.

Lung ultrasound as a tool to guide respiratory physiotherapy.

Lung ultrasound (LUS) is becoming an invaluable tool in the management of critically ill patients. We report two cases showing the importance of LUS as a guide to optimize respiratory physiotherapy in the intensive care unit, allowing a successful lung donation process and to redirect the physiotherapist's approach. The use of LUS requires an adequate training but it is becoming an important tool in management algorithms for critically ill patients.

Age and growth of Brauer's lanternfish Gymnoscopelus braueri and rhombic lanternfish Krefftichthys anderssoni (Family Myctophidae) in the Scotia Sea, Southern Ocean.

This study examines age and growth of Brauer's lanternfish Gymnoscopelus braueri and rhombic lanternfish Krefftichthys anderssoni from the Scotia Sea in the Southern Ocean, through the analysis of annual growth increments deposited on sagittal otoliths. Otolith pairs from 177 G. braueri and 118 K. anderssoni were collected in different seasons from the region between 2004 and 2009. Otolith-edge analysis suggested a seasonal change in opaque and hyaline depositions, indicative of an annual growth pattern, although variation within the populations of both species was apparent. Age estimates varied from 1 to 6 years for G. braueri (40 to 139 mm standard length; LS ) and from 0 to 2 years for K. anderssoni (26 to 70 mm LS ). Length-at-age data were broadly consistent with population cohort parameters identified in concurrent length-frequency data from the region for both species. The estimated values of von Bertalanffy growth curves for G. braueri were L∞ = 133.22 mm, k = 0.29 year-1 and t0 = -0.21 year and the values for K. anderssoni were L∞ = 68.60 mm, k = 0.71 year-1 and t0 = -0.49 year. There were no significant (P > 0.05) differences in growth between sexes for either species, suggesting that males and females have similar growth and development trajectories in the Scotia Sea. A positive allometric relationship between LS and wet mass was found for each species, as well as a significant (P < 0.0001) linear relationship between otolith size and LS . Growth performance (Ф') was similar between the two species and congruent with other myctophid species across the Southern Ocean. This study provides important parameters for future Southern Ocean ecosystem studies in a resource management context.

Deep-water fisheries along the British Isles continental slopes: status, ecosystem effects and future perspectives.

In this paper, we revisit the state of deep-water fisheries to the west of the British Isles and aim to provide an overview on the key drivers behind community changes along continental margins. The deep-water fisheries to the west of the British Isles that extend from the shelf-slope break down to the lower slope and along banks and seamounts of the Rockall Basin, mainly target blue ling Molva dypterygia, roundnose grenadier Coryphaenoides rupestris, orange roughy Hoplostethus atlanticus, with by-catches of black scabbardfish Aphanopus carbo and tusk Brosme brosme. These fishing grounds experienced a long period of exhaustive exploitation until the early 2000s, but subsequently the implementation of management strategies has helped to relieve excessive fishing pressure. It is widely accepted that a better understanding of the long-term implications of disturbance is needed to understand patterns in deep-water communities and what sustainable use and exploitation of resources might look like in this context.

Analysis of stable isotope ratios in blood of tracked wandering albatrosses fails to distinguish a δ(13) C gradient within their winter foraging areas in the southwest Atlantic Ocean.

RATIONALE: The main limitation of isotopic tracking for inferring distribution is the lack of detailed reference maps of the isotopic landscape (i.e. isoscapes) in the marine environment. Here, we attempt to map the marine δ(13) C isoscape for the southwestern sector of the Atlantic Ocean, and assess any temporal variation using the wandering albatross as a model species. METHODS: Tracking data and blood and diet samples were collected monthly from wandering albatrosses rearing chicks at Bird Island, South Georgia, during the austral winter between May and October 2009. The δ(13) C and δ(15) N values were measured by mass spectrometry in plasma and blood cells, and related to highly accurate data on individual movements and feeding activity obtained using three types of device: GPS, activity (immersion) loggers and stomach temperature probes. RESULTS: The tracked birds foraged in waters to the north or northwest of South Georgia, including the Patagonian shelf-break, as far as 2000 km from the colony. The foraging region encompassed the two main fronts in the Southern Ocean (Polar and Subantarctic fronts). The δ(13) C values varied by only 2.1 ‰ in plasma and 2.5 ‰ in blood cells, and no relationships were found between the δ(13) C values in plasma and the mean latitude or longitude of landings or feeding events of each individual. CONCLUSIONS: The failure to distinguish a major biogeographic gradient in δ(13) C values suggest that these values in the south Atlantic Ocean are fairly homogeneous. There was no substantial variation among months in either the δ(13) C or the δ(15) N values of plasma or blood cells of tracked birds. As birds did not show a significant change in diet composition or foraging areas during the study period, these results provide no evidence for major temporal variation in stable isotope ratios in consumer tissues, or in the regional marine isoscape in the austral winter of 2009.

Red and processed meat intake and risk of colorectal adenomas: a systematic review and meta-analysis of epidemiological studies.

BACKGROUND: Current evidence indicates that red and processed meat intake increases the risk of colorectal cancer; however, the association with colorectal adenomas is unclear. OBJECTIVE: To conduct a systematic review and meta-analysis of epidemiological studies of red and processed meat intake and risk of colorectal adenomas as part of the Continuous Update Project of the World Cancer Research Fund. DESIGN: PubMed and several other databases were searched for relevant studies from their inception up to 31 December 2011. Summary relative risks (RRs) were estimated using a random effects model. RESULTS: Nineteen case-control studies and seven prospective studies were included in the analyses. The summary RR per 100 g/day of red meat was 1.27 (95 % CI 1.16-1.40, I (2) = 5 %, n = 16) for all studies combined, 1.20 (95 % CI 1.06-1.36, I (2) = 0 %, n = 6) for prospective studies, and 1.34 (95 % CI 1.12-1.59, I (2) = 31 %, n = 10) for case-control studies. The summary RR per 50 g/day of processed meat intake was 1.29 (95 % CI 1.10-1.53, I (2) = 27 %, n = 10) for all studies combined, 1.45 (95 % CI 1.10-1.90, I (2) = 0 %, n = 2) for prospective studies, and 1.23 (95 % CI 0.99-1.52, I (2) = 37 %, n = 8) for case-control studies. There was evidence of a nonlinear association between red meat (p nonlinearity < 0.001) and processed meat (p nonlinearity = 0.01) intake and colorectal adenoma risk. CONCLUSION: These results indicate an elevated risk of colorectal adenomas with intake of red and processed meat, but further prospective studies are warranted.

Influence of cheese making process on STEC bacteriophage release.

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens implicated in diseases including hemolytic uremic syndrome (HUS) and hemorrhagic colitis (HC). The main virulence factor are Shiga toxins; their production and secretion are by-products of the expression of late genes of prophages upon sub-lethal environmental stimuli exposure. Hence, the lysogenic prophage after a stress switch to lytic cycle spreading the Stx phages. In the present study, 35 STEC were screened for the presence and the ability to release Shiga toxin-encoding bacteriophages. Three bacterial strains showed signals of prophage presence both in plate and in PCR. Subsequently, these bacterial strains were subjected to stressors that simulate cheese manufacturing conditions: NaCl (1, 1.5 and 2% w/v), lactic acid (0.5, 1.5 and 3% v/v), anaerobic growth, pasteurization (72°C for 15 s), UV irradiation. The ability to release prophage was evaluated by Real Time qPCR. Induction of the prophages showed that the addition of NaCl at 1.5 and 2% significantly increased viral release compared to control. Conversely, the addition of lactic acid had a significant repressive effect. The other applied stressors had no significant effect in phage release according to the experimental conditions adopted.

Assessing higher education students' critical thinking with the PENCRISAL test - Portuguese short version: a psychometric study.

The development of critical thinking in higher education is fundamental, preparing students to think well, find explanations, make decisions and solve problems. Given the importance of its promotion, its assessment is crucial, since the two are inseparable. Moreover, the number of instruments that are validated to assess critical thinking in the Portuguese language and culture are scarce. We present the validation psychometric study of the PENCRISAL test (short version) to the Portuguese language, a critical thinking assessment test for higher education students, designed and validated in Spain (full and short version), which presents adequate reliability and validity psychometric characteristics to assess key-dimensions of critical thinking. A sample of 225 Portuguese higher education students from three universities (two public and one private) performed a reduced version of the PANCRISAL test. The results obtained allowed replicating the Spanish reduced version in Portugal (only changing one of the six items), and the confirmatory factorial analysis permits to identify two factors intercorrelated, legitimizing the combination of the six items in a global score. This short version can be used as a screening test, and its potential is pointed out to assess students critical thinking to support teaching and research in higher education.

Clinical supervision strategies, learning, and critical thinking of nursing students.

OBJECTIVE: To identify the supervisory strategies that Nursing students consider facilitators of the development of critical thinking skills in clinical teaching. METHODS: This is a qualitative study, within the interpretative paradigm, using the focus group methodology. Eight undergraduate nursing students participated in the study. RESULTS: Participants recognized the indispensability of critical thinking for professional responsibility and quality of care and highlighted the importance of using supervisory strategies adapted to their needs, learning objectives, and the context of clinical practice. FINAL CONSIDERATIONS: This study highlights the urgent need to establish, within the Nursing curricula, clinical supervision strategies that promote critical thinking and favor the development of skills for good clinical judgment, problem solving, and safe, effective, and ethical decision-making.

Nonlinear reduction in risk for colorectal cancer by fruit and vegetable intake based on meta-analysis of prospective studies.

BACKGROUND & AIMS: The association between fruit and vegetable intake and colorectal cancer risk has been investigated by many studies but is controversial because of inconsistent results and weak observed associations. We summarized the evidence from cohort studies in categorical, linear, and nonlinear, dose-response meta-analyses. METHODS: We searched PubMed for studies of fruit and vegetable intake and colorectal cancer risk that were published until the end of May 2010. We included 19 prospective studies that reported relative risk estimates and 95% confidence intervals (CIs) of colorectal cancer-associated with fruit and vegetable intake. Random effects models were used to estimate summary relative risks. RESULTS: The summary relative risk for the highest vs the lowest intake was 0.92 (95% CI: 0.86-0.99) for fruit and vegetables combined, 0.90 (95% CI: 0.83-0.98) for fruit, and 0.91 (95% CI: 0.86-0.96) for vegetables (P for heterogeneity=.24, .05, and .54, respectively). The inverse associations appeared to be restricted to colon cancer. In linear dose-response analysis, only intake of vegetables was significantly associated with colorectal cancer risk (summary relative risk=0.98; 95% CI: 0.97-0.99), per 100 g/d. However, significant inverse associations emerged in nonlinear models for fruits (Pnonlinearity<.001) and vegetables (Pnonlinearity=.001). The greatest risk reduction was observed when intake increased from very low levels of intake. There was generally little evidence of heterogeneity in the analyses and there was no evidence of small-study bias. CONCLUSIONS: Based on meta-analysis of prospective studies, there is a weak but statistically significant nonlinear inverse association between fruit and vegetable intake and colorectal cancer risk.

Height and pancreatic cancer risk: a systematic review and meta-analysis of cohort studies.

BACKGROUND: Greater height has been associated with increased risk of several cancers, but epidemiological data on height and pancreatic cancer are inconclusive. We conducted a systematic review and meta-analysis of prospective studies to clarify these results. METHODS: PubMed and several other databases were searched up to September 2011. Prospective studies of height and pancreatic cancer were included. Summary relative risks were estimated by the use of a random effects model. RESULTS: We identified twelve cohort studies that were included in the meta-analysis. The summary RR per 5-cm increase in height was 1.07 (95 % CI: 1.03-1.12, I (2) = 57 %). The results were similar among men and women. The summary estimate was attenuated when we included results from two pooled analyses together with these studies, summary RR = 1.03 (95 % CI: 1.00-1.07, I (2) = 44 %). CONCLUSIONS: This meta-analysis of cohort studies provides further evidence that greater adult attained height is associated with increased pancreatic cancer risk. However, given the unexplained heterogeneity, further studies are needed before a conclusion can be drawn.

Ecophysiological effects of mercury bioaccumulation and biochemical stress in the deep-water mesopredator Etmopterus spinax (Elasmobranchii; Etmopteridae).

Mercury (Hg) is a non-essential metal that can have toxic effects on the fitness of organisms and tends to bioaccumulate with age and to biomagnify in higher trophic levels. Few studies have assessed oxidative stress and neurotoxicity in deep-water sharks. This study evaluated early ontogenetic changes and physiological effects (antioxidant defences, oxidative damage, aerobic metabolism and neurotransmission functions) of Hg accumulation in the white muscle and brain tissues of the velvet belly lantern shark Etmopterus spinax from the southern Iberian coast (NE Atlantic). Results suggested that the low mercury concentrations observed may induce acute effects in E. spinax before they reach sexual maturity. We found different Hg concentrations in E. spinax: [Hg] males > [Hg] females; [Hg] muscle > [Hg] brain. Females appeared to have higher redox capability translated into higher activities and levels of antioxidant defences than males. However, higher levels of oxidative damage were also observed in females. Whilst the mechanisms underlying these effects remain unknown, these results suggest differences in mercury accumulation between tissues and sex, and potentially deleterious effects on oxidative stress status and neurophysiology of E. spinax, potentially impairing swimming performance and reproduction, which could subsequently impact on the health of both individuals and population.

Clinical Challenges in Pedophilia-Themed Obsessive-Compulsive Disorder.

In obsessive-compulsive disorder, pedophilia-themed obsessions-distressing intrusive thoughts about being sexually attracted to, or sexually abusing, children-are the most distressing for patients and the most misdiagnosed among healthcare professionals. Our aim is to present a case report highlighting the role stigma plays in delaying treatment, the clinical challenges in the diagnosis, and in the treatment of pedophilia-themed obsessive-compulsive disorder, in order to address the lack of literature on the subject. The case concerns a 33-year-old man with suicidal thoughts associated with the unbearable suffering caused by pedophilia-themed obsessions he had been having over the previous decade, without ever asking for help. This situation was highly disabling, leaving him mostly isolated in his bedroom. After the differential diagnosis was made, a treatment plan combining pharmacological and cognitive-behavioural therapy was implemented. After 18 months he showed a degree of remission that made it possible for him to apply for a job.

Na perturbação obsessivo-compulsiva as obsessões pedofílicas - pensamentos intrusivos sobre ser sexualmente excitado, ou abusar sexualmente, de crianças - estão entre os mais angustiantes para os doentes e os mais incorretamente diagnosticados pelos profissionais de saúde. O nosso objetivo é apresentar um caso clínico destacando o papel que o estigma tem no atraso do início do tratamento e os desafios clínicos que se verificam em relação ao diagnóstico e ao tratamento desta perturbação, de modo a colmatar a falta de literatura sobre o assunto. O caso é relativo a um homem de 33 anos, com ideação suicida associada ao sofrimento insuportável causado pelas obsessões sexuais pedofílicas que tinha desde há uma década, sem nunca ter recorrido a um profissional de saúde. Esta situação teve muito impacto no seu funcionamento deixando-o maioritariamente isolado no seu quarto. Após o diagnóstico diferencial, implementou-se o projeto terapêutico combinando tratamento farmacológico e psicoterapia cognitivo-comportamental. Após 18 meses o doente apresentou uma melhoria significativa permitindo-o concorrer a um emprego.

Development of an online digital resource accessible for students with visual impairment or blindness: Challenges and strategies.

BACKGROUND: People with visual impairment or blindness face a wide range of daily barriers, both at school and at work. OBJECTIVE: This article describes the development process of an online resource, addressing Occupational Safety and Health (OSH), accessible for students with visual impairment or blindness. METHODS: This study was framed in a Design-Based Research methodology involving the analysis, design, development and implementation of a digital resource. In the analysis stage, a first list of accessibility challenges was created allowing the design of strategies and specific technical solutions to approach them. RESULTS: The development process has shown that online digital resources can be accessible for users with visual impairment or blindness and even the most visual contents and activities (based on images and videos) can be easily adjusted. CONCLUSIONS: Online accessible resources should be based on the World Wide Web Consortium (W3C) guidelines, allowing the proper description of all contents by screen readers, using audio description, accessible features and providing keyboard navigation. Further research must be conducted to deepen knowledge on the role of educational digital resources for students with visual impairment or blindness, namely regarding OSH barriers that workers with visual impairment or blindness face at the workplace (as visual safety signs and pictogram labels).

A framework for the development of a global standardised marine taxon reference image database (SMarTaR-ID) to support image-based analyses.

Video and image data are regularly used in the field of benthic ecology to document biodiversity. However, their use is subject to a number of challenges, principally the identification of taxa within the images without associated physical specimens. The challenge of applying traditional taxonomic keys to the identification of fauna from images has led to the development of personal, group, or institution level reference image catalogues of operational taxonomic units (OTUs) or morphospecies. Lack of standardisation among these reference catalogues has led to problems with observer bias and the inability to combine datasets across studies. In addition, lack of a common reference standard is stifling efforts in the application of artificial intelligence to taxon identification. Using the North Atlantic deep sea as a case study, we propose a database structure to facilitate standardisation of morphospecies image catalogues between research groups and support future use in multiple front-end applications. We also propose a framework for coordination of international efforts to develop reference guides for the identification of marine species from images. The proposed structure maps to the Darwin Core standard to allow integration with existing databases. We suggest a management framework where high-level taxonomic groups are curated by a regional team, consisting of both end users and taxonomic experts. We identify a mechanism by which overall quality of data within a common reference guide could be raised over the next decade. Finally, we discuss the role of a common reference standard in advancing marine ecology and supporting sustainable use of this ecosystem.

Clinical supervision strategies, learning, and critical thinking of nursing students / Estrategias de supervisión clínica, aprendizaje y pensamiento crítico de los estudiantes de Enfermería / Estratégias de supervisão clínica, aprendizagem e pensamento crítico dos estudantes de Enfermagem

ABSTRACT Objective: To identify the supervisory strategies that Nursing students consider facilitators of the development of critical thinking skills in clinical teaching. Methods: This is a qualitative study, within the interpretative paradigm, using the focus group methodology. Eight undergraduate nursing students participated in the study. Results: Participants recognized the indispensability of critical thinking for professional responsibility and quality of care and highlighted the importance of using supervisory strategies adapted to their needs, learning objectives, and the context of clinical practice. Final considerations: This study highlights the urgent need to establish, within the Nursing curricula, clinical supervision strategies that promote critical thinking and favor the development of skills for good clinical judgment, problem solving, and safe, effective, and ethical decision-making.

RESUMEN Objetivo: Identificar las estrategias de supervisión que los estudiantes de Enfermería consideran facilitadoras del desarrollo de las capacidades de pensamiento crítico en el contexto de enseñanza clínica. Métodos: Estudio de naturaleza cualitativa, inserido en el paradigma interpretativo, con recurso a la metodología focus group. Participaron del estudio ocho estudiantes del curso de licenciatura en Enfermería. Resultados: Los participantes reconocieron la imprescindibilidad del pensamiento crítico para la responsabilidad profesional y calidad en la asistencia; y destacaron la importancia de la utilización de estrategias de supervisión adecuadas a sus necesidades, a los objetivos de aprendizaje y al contexto de la práctica clínica. Consideraciones finales: Este estudio sobrepasa la urgencia en establecerse, dentro de los currículos del curso de Enfermería, estrategias de supervisión clínica promotoras del pensamiento crítico, que favorezcan el desarrollo de capacidades para el bueno juicio clínico, resolución de problemas y toma de decisión segura, eficaz y ética.

RESUMO Objetivo: Identificar as estratégias supervisivas que os estudantes de Enfermagem consideram facilitadoras do desenvolvimento das capacidades de pensamento crítico no contexto de ensino clínico. Métodos: Estudo de natureza qualitativa, inserido no paradigma interpretativo, com recurso à metodologia focus group. Participaram do estudo oito estudantes do curso de licenciatura em Enfermagem. Resultados: Os participantes reconheceram a imprescindibilidade do pensamento crítico para a responsabilidade profissional e qualidade na assistência; e destacaram a importância da utilização de estratégias supervisivas adequadas às suas necessidades, aos objetivos de aprendizagem e ao contexto da prática clínica. Considerações finais: Este estudo sobreleva a premência em se estabelecer, dentro dos currículos do curso de Enfermagem, estratégias de supervisão clínica promotoras do pensamento crítico, que favoreçam o desenvolvimento de capacidades para o bom julgamento clínico, resolução de problemas e tomada de decisão segura, eficaz e ética.

Deep-sea crustacean trawling fisheries in Portugal: quantification of effort and assessment of landings per unit effort using a Vessel Monitoring System (VMS).

Mapping and quantifying bottom trawling fishing pressure on the seafloor is pivotal to understand its effects on deep-sea benthic habitats. Using data from the Vessel Monitoring System of crustacean trawlers along the Portuguese margin, we have identified the most exploited areas and characterized the most targeted habitats and water depths. We estimated a total trawling effort of 69596, 66766, and 63427 h y-1 for the years 2012, 2013, and 2014 respectively which, considering the total landings estimated for this gear, yield values of 20.76, 21.06, and 19.11 kg of landed fish per trawled hour. The main trawling pressure is exerted in the South and Southwest Portuguese margins, on muddy and muddy-sand bottoms between 200 and 700 m water depths, while in the North and Central-West coasts a minor effort, at shallower waters and across a wider range of habitats, is also applied. The most landed species are crustaceans such as rose shrimp and Norway lobster, although this varies importantly between the different regions of Portugal, being fish and cephalopods the main captures in the Northern ports. We discuss the consequences of trawling for the impacted communities as well as the characteristics of the commercialization of these captures in Portugal.

Sexual and individual foraging segregation in Gentoo penguins Pygoscelis papua from the Southern Ocean during an abnormal winter.

Knowledge about sexual segregation and gender-specific, or indeed individual specialization, in marine organisms has improved considerably in the past decade. In this context, we tested the "Intersexual Competition Hypothesis" for penguins by investigating the feeding ecology of Gentoo penguins during their austral winter non-breeding season. We considered this during unusual environmental conditions (i.e. the year 2009 had observations of high sea surface and air temperatures) in comparison with the long term average at Bird Island, South Georgia. Through conventional (i.e. stomach contents) and stable isotopic values from red blood cells, plasma and feathers of both male and female Gentoo penguins, we showed that there were significant differences between sexes, with males feeding mainly on fish (54% by mass) followed by crustaceans (38%) whereas females fed mainly on crustaceans (89% by mass) followed by fish (4%). Themisto gaudichaudii was the most important crustacean prey for males (64% by mass; 82% by number; 53% by frequency of occurrence) and females (63% by mass; 77% by number; 89% by frequency of occurrence), contrasting with all previous studies that found Antarctic krill Euphausia superba were generally the main prey. Stable isotopic data showed that, in terms of habitat use (based on δ 13C), there were significant differences in short-term carbon signatures between males and females (based on plasma and red blood cells), suggesting that both sexes explored different habitats, with females exploring more offshore pelagic waters and males feeding more in coastal benthic waters. Based on δ 15N, males fed on significantly higher trophic level than females (based on plasma and red blood cells), in agreement with our diet results., Thus, Gentoo penguins behave in a similar manner to other non-breeding penguins species (e.g. king, macaroni and rockhopper penguins), albeit at a smaller spatial scale (as they do not disperse as these other penguins do), in that they have a wider habitat and trophic niche during the Antarctic Winter (in comparison to Summer). We also detected individual specialization in feeding/trophic levels for each gender, with certain males feeding mainly on fish and certain females mainly on crustaceans, which may be driven the prevailing environmental conditions that lead individuals to search for alternative prey, and cause sexual diet segregation. Our results provide further information to help improve understanding about sexual segregation and individual specialization of marine organisms, while contributing valuable information on the winter diet for Antarctic monitoring programs and for modelling Antarctic marine food webs.