1,222 research outputs found
Fish Ecology, Evolution, and Exploitation: A New Theoretical Synthesis Monographs in population biology ;, 62./ Ken H. Andersen.
No full textFish are one of the most important global food sources, supplying a significant share of the world's protein consumption. From stocks of wild Alaskan salmon and North Sea cod to entire fish communities with myriad species, fisheries require careful management to ensure that stocks remain productive, and mathematical models are essential tools for doing so. Fish Ecology, Evolution, and Exploitation is an authoritative introduction to the modern size- and trait-based approach to fish populations and communities.Ken Andersen covers the theoretical foundations, mathematical formulations, and real-world applications of this powerful new modeling method, which is grounded in the latest ecological theory and population biology. He begins with fundamental assumptions on the level of individuals and goes on to cover population demography and fisheries impact assessments. He shows how size- and trait-based models shed new light on familiar fisheries concepts such as maximum sustainable yield and fisheries selectivity--insights that classic age-based theory can't provide--and develops novel evolutionary impacts of fishing. Andersen extends the theory to entire fish communities and uses it to support the ecosystem approach to fisheries management, and forges critical links between trait-based methods and evolutionary ecology.Accessible to ecologists with a basic quantitative background, this incisive book unifies the thinking in ecology and fisheries science and is an indispensable reference for anyone seeking to apply size- and trait-based models to fish demography, fisheries impact assessments, and fish evolutionary ecology.Cover; Contents; Preface; Notation; 1. Nothing as Practical as a Good Theory; 1.1 What Characterizes a Good Theory?; 1.2 How to Read This Book; Part I. Individuals; 2. Size Spectrum Theory; 2.1 What Is Body Size?; 2.2 What Is a Size Spectrum?; 2.3 Scaling of Physiology with Body Size; 2.4 What Is the Size Spectrum Exponent?; 2.5 What Is the Predation Mortality?; 2.6 How Long Are Marine Food Chains?; 2.7 What Is the Trophic Efficiency?; 2.8 Summary; 3. Individual Growth and Reproduction; 3.1 The von Bertalanffy Growth Model; 3.2 Asymptotic Size as a Master Trait3.3 Bioenergetic Formulation of the Growth Equation3.4 Which Other Traits Describe Fish Life Histories?; 3.5 Summary; Part II. Populations; 4. Demography; 4.1 What Is the Size Structure of a Population?; 4.2 Reproduction, Recruitment, and Density Dependence; 4.3 Why Use a Stock-Recruitment Relation?; 4.4 What Is the Physiological Mortality?; 4.5 Summary; 5. Fishing; 5.1 Fisheries Selectivity; 5.2 Impact of Fishing on Small and Large Species; 5.3 Fisheries Reference Points; 5.4 Which Gear Selectivity Maximizes Yield?; 5.5 Summary; 6. Fisheries-Induced Evolution6.1 Which Selection Responses Do We Expect?6.2 Quantitative Genetics; 6.3 Evolutionary Impact Assessment of Fishing; 6.4 Summary: What Is an Evolutionary Enlightened Fisheries Management?; 7. Population Dynamics; 7.1 What Is the Population Growth Rate?; 7.2 How Fast Does a Population Recover from Overfishing?; 7.3 How Does a Population Respond to Environmental Fluctuations?; 7.4 Summary; Part III. Traits; 8. Teleosts versus Elasmobranchs; 8.1 How Do Teleosts and Elasmobranchs Differ?; 8.2 How Sensitive Are Elasmobranchs to Fishing?; 8.3 Why Do Teleosts Make Small Eggs?8.4 Why Do Elasmobranchs Make Large Offspring?8.5 Summary; 9. Trait-Based Approach to Fish Ecology; 9.1 Life-History Strategies; 9.2 Traits and Trade-offs; 9.3 The Sweet Spot of Complexity; Part IV. Communities; 10. Consumer-Resource Dynamics and Emergent Density Dependence; 10.1 A Consumer-Resource Model; 10.2 Emergent Density Dependence; 10.3 When in Life Does Density Dependence Occur?; 10.4 Fishing on a Stock with Emergent Density Dependence; 10.5 Summary; 11. Trait Structure of the Fish Community; 11.1 Structure of an Unfished Community; 11.2 Dynamic Community Model11.3 Dynamic Community Model versus Analytic Theory11.4 Species versus Traits; 11.5 Summary; 12. Community Effects of Fishing; 12.1 Trophic Cascades; 12.2 What Is the Impact of Forage Fishing?; 12.3 What Is the Maximum Sustainable Yield of a Community?; 12.4 Size- and Trait-Based Models for Ecosystem-Based Fisheries Management; Part V. Epilogue; 13. The Size- and Trait-Based Approach; 13.1 Size versus Age-Based Approaches for Fisheries Science; 13.2 Future Directions of Size- and Trait-Based Theory; Part VI. Appendixes; A. Single Stock Size Spectrum Model; B. Consumer-Resource Model1 online resource
Food-web dynamics under climate change
No full textClimate change affects ecological communities through its impact on the physiological performance of individuals. However, the population dynamic of species well inside their thermal niche is also determined by competitors, prey and predators, in addition to being influenced by temperature changes. We use a trait-based food-web model to examine how the interplay between the direct physiological effects from temperature and the indirect effects due to changing interactions between populations shapes the ecological consequences of climate change for populations and for entire communities. Our simulations illustrate how isolated communities deteriorate as populations go extinct when the environment moves outside the species' thermal niches. High-trophic-level species are most vulnerable, while the ecosystem function of lower trophic levels is less impacted. Open communities can compensate for the loss of ecosystem function by invasions of new species. Individual populations show complex responses largely uncorrelated with the direct impact of temperature change on physiology. Such complex responses are particularly evident during extinction and invasion events of other species, where climatically well-adapted species may be brought to extinction by the changed food-web topology. Our results highlight that the impact of climate change on specific populations is largely unpredictable, and apparently well-adapted species may be severely impacted.</jats:p
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A middleware independent grid workflow builder for scientific applications
No full textGrid workflow authoring tools are typically specific to particular workflow engines built into Grid middleware, or are application specific and are designed to interact with specific software implementations. g-Eclipse is a middleware independent Grid workbench that aims to provide a unified abstraction of the Grid and includes a Grid workflow builder to allow users to author and deploy workflows to the Grid. This paper describes the g-Eclipse Workflow Builder and its implementations for two Grid middlewares, gLite and GRIA, and a case study utilizing the Workflow Builder in a Grid user's scientific workflow deployment
Fish Ecology, Evolution, and Exploitation:A New Theoretical Synthesis
No full textFish are one of the most important global food sources, supplying a significant share of the world’s protein consumption. From stocks of wild Alaskan salmon and North Sea cod to entire fish communities with myriad species, fisheries require careful management to ensure that stocks remain productive, and mathematical models are essential tools for doing so. Fish Ecology, Evolution, and Exploitation is an authoritative introduction to the modern size- and trait-based approach to fish populations and communities.Ken Andersen covers the theoretical foundations, mathematical formulations, and real-world applications of this powerful new modeling method, which is grounded in the latest ecological theory and population biology. He begins with fundamental assumptions on the level of individuals and goes on to cover population demography and fisheries impact assessments. He shows how size- and trait-based models shed new light on familiar fisheries concepts such as maximum sustainable yield and fisheries selectivity—insights that classic age-based theory can’t provide—and develops novel evolutionary impacts of fishing. Andersen extends the theory to entire fish communities and uses it to support the ecosystem approach to fisheries management, and forges critical links between trait-based methods and evolutionary ecology.Accessible to ecologists with a basic quantitative background, this incisive book unifies the thinking in ecology and fisheries science and is an indispensable reference for anyone seeking to apply size- and trait-based models to fish demography, fisheries impact assessments, and fish evolutionary ecology
Linking plankton size spectra and community composition to carbon export and its efficiency
No full textThe magnitude and efficiency of particulate carbon export from the ocean surface depends not only on net primary production (NPP) but also on how carbon is consumed, respired, and repackaged by organisms. We contend that several of these processes can be captured by the size spectrum of the plankton community. However, most global models have relatively simple food-web structures that are unable to generate plankton size spectra. Moreover, the life-cycles of multicellular zooplankton are typically not resolved, restricting the ability of models to represent time-lags that are known to impact carbon export and its efficiency (pe-ratio). Here, we use a global mechanistic size-spectrum model of the marine plankton community to investigate how particulate export and pe-ratio relate to the community size spectrum, community composition, and time-lags between predators and prey. The model generates emergent food-webs with associated size distributions for organisms and detrital particles. To resolve time-lags between phytoplankton and zooplankton, we implement the life-cycle of multicellular zooplankton (here represented by copepods). We find that carbon export correlates best with copepod biomass and trophic level, whereas the pe-ratio correlates best with the exponent of the size spectrum and sea surface temperature (SST). Community metrics performed better than NPP or SST for both deep export and pe-ratio. Time-lags between phytoplankton and copepods did not strongly affect export or pe-ratio. We conclude by discussing how can we reconcile size spectrum theory with field sampling
Feeding and growth of Atlantic cod (<i>Gadus morhua</i> L.) in the eastern Baltic Sea under environmental change
No full textFive decades of stomach content data allowed insight into the development of consumption, diet composition, and resulting somatic growth of Gadus morhua (Atlantic cod) in the eastern Baltic Sea. We show a recent reversal in feeding level over body length. Present feeding levels of small cod indicate severe growth limitation and increased starvation-related mortality. For young cod, the low growth rate and the high mortality rate are manifested through a reduction in size-at-age. The low feeding levels are likely the result of a decrease in benthic prey abundance due to increased hypoxic areas, while decreasing abundances of pelagic species in the area of cod distribution have prevented a compensatory shift in diet. Our study emphasizes that environmental forcing and the decline in pelagic prey caused changes in consumption and growth rates of small cod. The food reduction is amplified by stunted growth leading to high densities of cod of smaller size competing for the scarce resources. The average growth rate is negative, and only individuals with feeding levels well above average will survive, though growing slowly. These results suggest that the relation between consumption rate, somatic growth and predatorprey population densities is strongly environmentally mediated
Environmental and Parental Influences on Offspring Health and Growth in Great Tits (Parus major)
No full textPMCID: PMC3728352This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
High Frequency Functional Ultrasound in Mice
No full textFunctional ultrasound (fUS) is a relatively new imaging modality to study the brain with a high spatiotemporal resolution and a wide field-of-view. In fUS detailed images of cerebral blood flow and volume are used to derive functional information, as changes in local flow and/or volume may reflect neuronal activation through neurovascular coupling. Most fUS studies so far have been performed in rats. Translating fUS to mice, which is a favorable animal model for neuroscience, pleads for a higher spatial resolution than what has been reported so far. As a consequence the temporal sampling of the blood flow should also be increased in order to adequately capture the wide range in blood velocities, as the Doppler shifts are inversely proportional to the spatial resolution. Here we present our first detailed images of the mouse brain vasculature at high spatiotemporal resolution. In addition we show some early experimental work on tracking brain activity upon local electrical stimulation.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Signal Processing System
Electron emission from H-terminated diamond enhanced by polypyrrole grafting
No full textElectron emission plays an important role in diverse applications, from cold cathodes to chemical processes (solvated electrons, water purification), energy generation (thermionic or dye-sensitized solar cells), and even cancer treatment. Here we show that by surface treatment using electrochemically grown polypyrrole the secondary-electron emission and photoelectron emission from boron-doped diamond is enhanced even above the intensity of electron emission from the hydrogen-terminated surface with negative electron affinity. This enhancement is stable in air for at least one month and it persists also in vacuum after thermal annealing. Scanning electron microscopy, Kelvin probe force microscopy, total photoelectron yield spectroscopy as well as surface mapping by Auger and secondary ion mass spectroscopies are used to characterize and correlate the surface electronic and chemical properties. A model of the electron emission enhancement is provided. (C) 2020 Elsevier Ltd. All rights reserved.Theworkhasbeensupportedby the projects CAAS(CZ.02.1.01/0.0/0.0/16_019/0000778), CEITEC Nanothorn (CZ.02.1.01/0.0/0.0/16_013/0001728) and Solid21 (CZ.02.1.01/0.0/0.0/16_019/0000760). We acknowledge also CzechNanoLab Research Infrastructure supported by MEYS CR (LM2018110). Kind support from JSPS is gratefully appreciated (BR, DT).Ukraintsev, E (corresponding author), Czech Tech Univ, Fac Elect Engn, Tech 2, Prague 6 16627, Czech Republic.
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