Isotopic niche variability in macroconsumers of the East Scotia Ridge (Southern Ocean) hydrothermal vents: What more can we learn from an ellipse?

Aspects of between-individual trophic niche width can be explored through the isotopic niche concept. In many cases isotopic variability can be influenced by the scale of sampling and biological characteristics including body size or sex. Sample size-corrected (SEAc) and Bayesian (SEAb) standard ellipse areas and generalised least squares (GLS) models were used to explore the spatial variability of δ13C and δ15N in Kiwa tyleri (decapod), Gigantopelta chessoia (peltospirid gastropod) and Vulcanolepas scotiaensis (stalked barnacle) collected from 3 hydrothermal vent field sites (E2, E9N and E9S) on the East Scotia Ridge (ESR), Southern Ocean. SEAb only revealed spatial differences in isotopic niche area in male K. tyleri. However, the parameters used to draw the SEAc, eccentricity (E) and angle of the major SEAc axis to the x-axis (θ), indicated spatial differences in the relationships between δ13C and δ15N in all 3 species. The GLS models indicated that there were spatial differences in isotope-length trends, which were related to E and θ of the SEAc. This indicated that E and θ were potentially driven by underlying trophic and biological processes that varied with body size. Examination of the isotopic niches using standard ellipse areas and their parameters in conjunction with length-based analyses provided a means by which a proportion of the isotopic variability within each species could be described. We suggest that the parameters E and θ offer additional ecological insight that has so far been overlooked in isotopic niche studies

The relationship between body mass index and sleep in women with risk factors for gestational diabetes mellitus

OnlinePublBackground: Both obesity and sleep disorders are common among women during pregnancy. Although prior research has identified a relationship between obesity and sleep disorders, those findings are from women later in pregnancy. Objective: To explore the relationships between self‐reported sleep duration, insufficient sleep and snoring with body mass index (BMI) among multiethnic women at risk of gestational diabetes mellitus (GDM)in early pregnancy.Methods: Cross‐sectional study of baseline data from women at risk of GDM enrolled in the Treatment of BOoking Gestational diabetes Mellitus (TOBOGM) multicentre trial across 12 Australian/Austrian sites. Participants completed a questionnaire before 20 weeks’ gestation to evaluate sleep. BMI 5 days/ month was higher in class II and class III obesity (1.38 (1.03–1.85) and 1.34 (1.01– 1.80), respectively), and the risk of snoring increased as BMI increased (1.59 (1.25– 2.02), 2.68 (2.07–3.48), 4.35 (3.21–5.88) to 4.96 (3.65–6.74), respectively)). Conclusions: Obesity is associated with insufficient sleep among pregnant women at risk of GDM. Snoring is more prevalent with increasing BMI.Pamela Acosta Reyes, Jincy Immanuel, William M. Hague, Helena Teede, Emily Hibbert, Christopher J. Nolan, Michael J. Peek, Vincent Wong, Jeffrey R. Flack, Mark McLean, Raiyomand Dalal, Jürgen Harreiter, Alexandra Kautzky, Willer, Rohit Rajagopal, Arianne Sweeting, Glynis P. Ross, Ngai Wah Cheung, David Simmon

Trophic position of meso-pelagic fishes in the western Mediterranean

Final workshop IDEADOS: The wrapping up of the IDEADOS project, International Workshop on Environment, Ecosystems and Demersal Resources and fisheries, 14-16 November 2012, Palma de Mallorca, SpainPeer reviewe

Structure and dynamics of food webs along the water column in the western Mediterranean elucidated by stable nitrogen and carbon isotope data

Final workshop IDEADOS: The wrapping up of the IDEADOS project, International Workshop on Environment, Ecosystems and Demersal Resources and fisheries, 14-16 November 2012, Palma de Mallorca, SpainPeer reviewe

Application of a predictive distribution formula to Bayesian computation for incomplete data models

We consider exact and approximate Bayesian computation in the presence of latent variables or missing data. Specifically we explore the application of a posterior predictive distribution formula derived in Sweeting And Kharroubi (2003), which is a particular form of Laplace approximation, both as an importance function and a proposal distribution. We show that this formula provides a stable importance function for use within poor man’s data augmentation schemes and that it can also be used as a proposal distribution within a Metropolis-Hastings algorithm for models that are not analytically tractable. We illustrate both uses in the case of a censored regression model and a normal hierarchical model, with both normal and Student t distributed random effects. Although the predictive distribution formula is motivated by regular asymptotic theory, it is not necessary that the likelihood has a closed form or that it possesses a local maximum

Trophic structure of mesopelagic fishes in the western Mediterranean based on stable isotopes of carbon and nitrogen

Special issue The wrapping up of the IDEADOS project: International Workshop on Environment, Ecosystems and Demersal Resources, and Fisheries.-- 11 pages, 5 figures, 2 tables.-- Corrigendum to: “Trophic structure of mesopelagic fishes in the western Mediterranean based on stable isotopes of carbon and nitrogen” [J. Mar. Syst. (2014) 138, 160–170], Journal of Marine Systems 139: 472-474 (2014) https://doi.org/10.1016/j.jmarsys.2014.09.001Mesopelagic fishes play an important role in the transfer of organic material in the photic zone to depth although the trophodynamic partitioning amongst co-existing and presumably competing species is unclear. This study employs combined carbon and nitrogen stable isotope analyses (δ13C and δ15N) of the 18 most abundant western Mediterranean mesopelagic fishes to explore niche partitioning in this group. Sampling was conducted along the water column from the shelf and slope grounds of the Balearic Islands in two contrasting periods (late autumn and summer). Trophodynamics were explored at assemblage level and at inter- and intra-species resolutions respectively using Bayesian diet mixing models and size specific behaviour respectively. Seasonal δ13C differences in near basal particulate organic matter (POM) and zooplankton fractions were almost directly replicated in higher fauna suggesting strong isotopic coupling between mesopelagic fishes and planktonic production. Despite reliance on similar basal production, species were segregated by trophic position with a graduation from 2.9 for the small Gonostomatidae Cyclothone braueri to 4.0 for the Myctophidae Lobianchia dofleini. Mixing model data reflected basic trophic position estimates with higher contributions of small fish and zooplankton/POM in higher and lower trophic level species respectively. Species could be categorized as showing preference for i) mesozooplankton/POM as for C. braueri, (in the lower TrL), ii) euphausiids and fish prey as for L. dofleini and the near bottom Lampanyctus crocodilus (in the upper TrL) and iii) mesozooplankton/euphausiids as Ceratoscopelus maderensis, Lampanyctus pusillus or the migrating L. crocodilus. There was little evidence of size based inter-population trophodynamics, with size-isotope trends explained by co-varying lipid content. © 2014 Elsevier B.V.The research was funded by project CTM2008-04489-C03-01 and 02. A. Bernal acknowledges predoctoral FPI Fellowship support BES-2009-013681 from Spain's Ministry of Science and Innovation. Isotope analyses were funded by the Government of the Balearic Islands, Acció especial: AAEE0138/09 (Direcció General de Recerca, Desenvolupament Tecnològic i Innovació, Conselleria d'Economia Hisenda i Innovació)Peer Reviewe

Diet and trophic levels of myctophids, gonostomatids and hatchetfish in the Western Mediterranean

Symposium on Integrating New Advances in Mediterranean Oceanography and Marine Biology, 26-29 November 2013, Institut de Ciències del Mar (CSIC), Barcelona, Catalunya, SpainMyctophids, gonostomatids and hatched-fishes constitute the most abundant pelagic fishes worldwide. Most myctophids perform extensive nyctimeral migrations across the water column from 200 to 1000 m depth, but gonostomatids and hatched-fishes remain under the epipelagic zone, the former tightly associated to the Deep Scattering Layer. As important components of the comprehensive mesopelagial, numerically, and as vehicles in the energy and matter fluxes through the feeding webs, the diet of 11 species of these fishes (Ceratoscopelus maderensis, Benthosema glaciale, Hygophum hygomii, H. benoiti, Lampanyctus crocodilus, L. pusillus, Lobianchia dofleini, Myctophum puctatum, Notoscopelus elongatus, Cyclotone braueri and Argyropelecus hemigymnus) was analyzed. In general, these predators were mainly zooplanktivores. A dietary shift towards larger or more nutritive prey was evident from transforming stages to adults. Medium-size myctophids contained mainly large calanoid copepods, while diets of transforming or smaller sizes of myctophids and hatched fishes were predominated by non-calanoids and microzooplankton. The adults of myctophid species that cease migrating or dwell longer periods close to the sea bottom, fed on macrozooplankton; in the case of L. crocodilus, on benthonic amphipods or decapods. Most myctophids showed high overlap of trophic niches, opposing to the general assumption of more selective strategies for oligotrophic areas with scarcity of food resources. However, certain degree of diet discrimination might be also detected. N. elongatus, L. pusillus and L. crocodilus captured with pelagic nets, ingested great proportions of Pleuromamma spp. and euphausiids. C. maderensis and L. dofleini consumed a miscellaneous of calanoids and, regularly, non-calanoids and soft prey such as larvaceans. M. punctatum and Hygophum spp. were euryphagic, and probably prey nonselectively upon the aggregated mesofauna. The stomiiforms, A. hemigymnus and C. braueri, fed almost exclusively on calanoids and oncaeids. A complementary examination of stable isotope (δ13C and δ15N) of both zooplankton and fishes cited above, allowed determining their trophic positions. Mesopelagic fishes ranged between the 3rd and the 4th level, the lowest value for the small non-migrating C. braueri. L. crocodilus showed significant higher δ13C and δ15N values in bottom-dwellers, which coincides with the unlike diet preferences observed in migrants of the same speciesPeer reviewe