A trait-based metric sheds new light on the nature of the body size-depth relationship in the deep sea

Summary 1. Variation within species is an often-overlooked aspect of community ecology, despite the fact that the ontogenetic structure of populations influences processes right up to the ecosystem level. Accounting for traits at the individual level is an important advance in the implementation of trait-based approaches in understanding community structure and function. 2. We incorporate individual- and species-level traits into one succinct assemblage structure metric, fractional size, which is calculated as the length of an individual divided by its potential maximum length. We test the implementation of fractional size in demersal fish assemblages along a depth gradient in the deep sea. We use data from an extensive trawl survey at depths of 300–2030 m on the continental slope of the Rockall Trough, Northeast Atlantic, to compare changes in fractional size structure along an environmental gradient to those seen using traditional taxonomic and trait-based approaches. 3. The relationship between fractional size and depth was particularly strong, with the overall pattern being an increase with depth, implying that individuals move deeper as they grow. Body size increased with depth at the intraspecific and assemblage levels. Fractional size, size structure and species composition all varied among assemblages, and this variation could be explained by the depth that the assemblage occupied. 4. The inclusion of individual-level traits and population fractional size structure adds to our understanding at the assemblage level. Fractional size, or where an individual is in its growth trajectory, appears to be an especially important driver of assemblage change with depth. This has implications for understanding fisheries impacts in the deep sea and how these impacts may propagate across depths

Using individual tracking data to validate the predictions of species distribution models

The authors would like to thank the College of Life Sciences of Aberdeen University and Marine Scotland Science which funded CP's PhD project. Skate tagging experiments were undertaken as part of Scottish Government project SP004. We thank Ian Burrett for help in catching the fish and the other fishermen and anglers who returned tags. We thank José Manuel Gonzalez-Irusta for extracting and making available the environmental layers used as environmental covariates in the environmental suitability modelling procedure. We also thank Jason Matthiopoulos for insightful suggestions on habitat utilization metrics as well as Stephen C.F. Palmer, and three anonymous reviewers for useful suggestions to improve the clarity and quality of the manuscript.Peer reviewedPostprintPostprintPostprintPostprintPostprin

Dependence of the micro-arcsecond metrology (MAM) testbed performance prediction on white light algorithm approach

MAM is a dedicated systems-level testbed that combines the major SIM subsystems including laser metrogy, pointing, and pathlength control. The testbed is configured as a modified Michelson interferometer for the purpose of studying the white-light fringe measurement processes. This paper will compare the performance of various algorithms using the MAM data, and will aid in our recommendation of how the SIM flight system should process the science and guide interferometer data

Deep Sea – Close Kin: A Genetic Approach for Improved Fisheries Management

Deep-sea fish stocks consist of species that live at depths of greater than 400 metres. While being important for EU fisheries, this natural renewable resource is particularly vulnerable to over-fishing, as many deep sea species are slow-growing and commonly of low fecundity. Generally little is known about the biology of deep sea species, and there prevails a substantial lack of scientific data on deep-sea stocks. This constitutes a major impediment to management strategies underpinning sustainable and profitable deep sea fisheries. Europe’s deep-sea fisheries began in the 1970’s and were entirely unregulated. The fleet grew as rewards were high, but many species were rapidly depleted. It was only in 2003 that a management plan was brought into action. While some measures to better protect commercially exploited deep sea fish have been adopted, such as the limitation of fishing effort or total allowable catches, these have been insufficient to allow stocks to recover and there is a general consensus that most deep-water stocks remain below safe biological limits for exploitation. In a recent communication to the Council and the European Parliament, the European Commission has emphasized the need to improve our knowledge on deep sea fish species to move away from the current prevailing unsustainable exploitation. Ideally, this would be the development of a robust and practical approach to estimate the abundance of deep sea species to support stock assessments and reduce the uncertainty about the state and rebuilding rates of commercially exploited deep sea stocks. The current rapid technology development and concurrent steep drop in costs of large-scale genotyping offers major opportunities for fisheries management. This report explores whether the concept of genetic close-kin abundance estimation, recently applied to establish biomass estimates of Southern Bluefin Tuna, can be applied to fisheries management of deep sea fish species.JRC.G.3-Maritime affair

Radio emission from extensive air showers

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Regulating Glucose and pH, and Monitoring Oxygen in a Bioreactor

A system that automatically regulates the concentration of glucose or pH in a liquid culture medium that is circulated through a rotating-wall perfused bioreactor is described. Another system monitors the concentration of oxygen in the culture medium

New cod war of words:'Cod is God' versus 'sod the cod'—Two opposed discourses on the North Sea Cod Recovery Programme

New insights into the North Sea Cod Recovery Programme (CRP), initiated in 2003 by the European Commission to reverse the long-term decline in cod stocks, are presented using discourse analysis. The main conservation measures taken under the CRP have been to reduce catch limits drastically and to increase control over vessels' fishing activities. There has been considerable controversy over the programme from its inception, with protagonists broadly divided into two discourses: (1) 'cod is God'-in which cod has assumed the status of the defining test of the European Union's (EU) resolve to manage fish stocks sustainably in EU waters; (2) 'sod the cod'-in which cod is regarded as one of a number of target commercial fish species, with no special status. Drawing on Frank Fischer's distinction between hegemonic and challenging discourses, we analyse the conflict between them at three levels: empirical; conceptual; and political. We consider moves to reconcile the two discourses in a policy consensus on a revised CRP, which suggest that the challenging discourse (sod-the-cod) has had some success in modifying the impact of the hegemonic discourse (cod-is-God

The Micro-Arcsecond Metrology Testbed

The Micro-Arcsecond Metrology (MAM) testbed is a ground-based system of optical and electronic equipment for testing components, systems, and engineering concepts for the Space Interferometer Mission (SIM) and similar future missions, in which optical interferometers will be operated in outer space. In addition, the MAM testbed is of interest in its own right as a highly precise metrological system. The designs of the SIM interferometer and the MAM testbed reflect a requirement to measure both the position of the starlight central fringe and the change in the internal optical path of the interferometer with sufficient spatial resolution to generate astrometric data with angular resolution at the microarcsecond level. The internal path is to be measured by use of a small metrological laser beam of 1,319-nm wavelength, whereas the position of the starlight fringe is to be estimated by use of a charge-coupled-device (CCD) image detector sampling a large concentric annular beam. For the SIM to succeed, the optical path length determined from the interferometer fringes must be tracked by the metrological subsystem to within tens of picometers, through all operational motions of an interferometer delay line and siderostats. The purpose of the experiments performed on the MAM testbed is to demonstrate this agreement in a large-scale simulation that includes a substantial portion of the system in the planned configuration for operation in outer space. A major challenge in this endeavor is to align the metrological beam with the starlight beam in order to maintain consistency between the metrological and starlight subsystems at the system level. The MAM testbed includes an optical interferometer with a white light source, all major optical components of a stellar interferometer, and heterodyne metrological sensors. The aforementioned subsystems are installed in a large vacuum chamber in order to suppress atmospheric and thermal disturbances. The MAM is divided into two distinct subsystems: the test article (TA), which is the interferometer proper, and the inverse interferometer pseudo-star (IIPS), which synthesizes the light coming from a distant target star by providing spatially coherent wavefronts out of two mirrors, separated by the MAM baseline, that feed directly into two siderostats that are parts of the TA. The two feed mirrors of the IIPS are articulated (in translation and tilt) in order to simulate stars located at different orientations in space, while still illuminating the TA siderostats. The spectrum of the simulated starlight of the IIPS corresponds to that of a blackbody at a temperature of about 3,100 K