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Worldwide, in recent years capture fisheries targeting lower-trophic level forage fish and euphausiid crustaceans have been substantial (similar to 20 million metric tons [MT] annually). Landings of forage species are projected to increase in the future, and this harvest may affect marine ecosystems and predator-prey interactions by removal or redistribution of biomass central to pelagic food webs. In particular, fisheries targeting forage fish and euphausiids may be in competition with seabirds, likely the most sensitive of marine vertebrates given limitations in their foraging abilities (ambit and gape size) and high metabolic rate, for food resources. Lately, apparent competition between fisheries and seabirds has led to numerous high-profile conflicts over interpretations, as well as the approaches that could and should be used to assess the magnitude and consequences of fisheries sea-bird resource competition. In this paper, we review the methods used to date to study fisheries competition with seabirds, and present "best practices" for future resource competition assessments. Documenting current fisheries competition with seabirds generally involves addressing two major issues: 1) are fisheries causing localized prey depletion that is sufficient to affect the birds? (i.e., are fisheries limiting food resources?), and 2) how are fisheries-induced changes to forage stocks affecting seabird populations given the associated functional or numerical response relationships? Previous studies have been hampered by mismatches in the scale of fisheries, fish, and seabird data, and a lack of causal understanding due to confounding by climatic and other ecosystem factors (e.g., removal of predatory fish). Best practices for fisheries-seabird competition research should include i) clear articulation of hypotheses, ii) data collection (or summation) of fisheries, fish, and seabirds on matched spatio-temporal scales, and integration of observational and experimental (including numerical simulation) approaches to establish connections and causality between fisheries and seabirds. As no single technique can provide all the answers to this vexing issue, an integrated approach is most promising to obtain robust scientific results and in turn the sustainability of forage fish fisheries from an ecosystem perspective.

Ecosystem-based management (EBM) in marine ecosystems considers impacts caused by complex interactions between environmental and anthropogenic pressures (i.e., oceanographic, climatic, socio-economic) and marine communities. EBM depends, in part, on ecological indicators that facilitate understanding of inherent properties and the dynamics of pressures within marine communities. Thresholds of ecological indicators delineate ecosystem status because they represent points at which a small increase in one or many pressure variables results in an abrupt change of ecosystem responses. The difficulty in developing appropriate thresholds and reference points for EBM lies in the multidimensionality of both the ecosystem responses and the pressures impacting the ecosystem. Here, we develop thresholds using gradient forest for a suite of ecological indicators in response to multiple pressures that convey ecosystem status for large marine ecosystems from the US Pacific, Atlantic, sub-Arctic, and Gulf of Mexico. We detected these thresholds of ecological indicators based on multiple pressures. Commercial fisheries landings above approximately 2–4.5 t km−2 and fisheries exploitation above 20–40% of the total estimated biomass (of invertebrates and fish) of the ecosystem resulted in a change in the direction of ecosystem structure and functioning in the ecosystems examined. Our comparative findings reveal common trends in ecosystem thresholds along pressure gradients and also indicate that thresholds of ecological indicators are useful tools for comparing the impacts of environmental and anthropogenic pressures across multiple ecosystems. These critical points can be used to inform the development of EBM decision criteria.

The oceans are changing more rapidly than ever before. Unprecedented climatic variability is interacting with unmistakable long‐term trends, all against a backdrop of intensifying human activities. What remains unclear, however, is how to evaluate whether conditions have changed sufficiently to provoke major responses of species, habitats, and communities. We developed a framework based on multimodel inference to define ecosystem‐based thresholds for human and environmental pressures in the California Current marine ecosystem. To demonstrate how to apply the framework, we explored two decades of data using gradient forest and generalized additive model analyses, screening for nonlinearities and potential threshold responses of ecosystem states (n = 9) across environmental (n = 6) and human (n = 10) pressures. These analyses identified the existence of threshold responses of five ecosystem states to four environmental and two human pressures. Both methods agreed on threshold relationships in two cases: (1) the winter copepod anomaly and habitat modification, and (2) sea lion pup production and the summer mode of the Pacific Decadal Oscillation (PDO). Considered collectively, however, these alternative analytical approaches imply that as many as five of the nine ecosystem states may exhibit threshold changes in response to negative PDO values in the summer (copepods, scavengers, groundfish, and marine mammals). This result is consistent with the idea that the influence of the PDO extends across multiple trophic levels, but extends current knowledge by defining the nonlinear nature of these responses. This research provides a new way to interpret changes in the intensities of human and environmental pressures as they relate to the ecological integrity of the California Current ecosystem. These insights can be used to make more informed assessments of when and under what conditions intervention, preparation, and mitigation may enhance progress toward ecosystem‐based management goals.

Marine ecosystems are complex, and there is increasing recognition that environmental, ecological, and human systems are linked inextricably in coastal regions. The purpose of this article was to integrate environmental, ecological and human dimensions information important for fisheries management into a common analytical framework. We then used the framework to examine the linkages between these traditionally separate subject areas. We focused on synthesis of linkages between the Gulf of Alaska marine ecosystem and human communities of practice, defined as different fisheries sectors. Our specific objective was to document the individual directional linkages among environmental, ecological, and human dimensions variables in conceptual models, then build qualitative network models to perform simulation analyses to test how bottom-up and top-down perturbations might propagate through these linkages. We found that it is both possible and beneficial to integrate environmental, ecological, and human dimensions information important for fisheries into a common framework. First, the conceptual models allowed us to synthesize information across a broad array of data types, representing disciplines such as ecology and economics that are more commonly investigated separately, often with distinct methods. Second, the qualitative network analysis demonstrated how ecological signals can propagate to human communities, and how fishery management measures may influence the system. Third, we found that incorporating multi-species interactions changed outcomes because the merged model reversed some of the ecological and human outcomes compared with single species analyses. Overall, we demonstrated the value of linking information from the natural and social sciences to better understand complex social–ecological systems, and the value of incorporating ecosystem-level processes into a traditionally single species management framework. We advocate for conceptual and qualitative network modelling as efficient foundational steps to inform ecosystem-based fisheries management.

Predator–prey interactions are a primary structuring force vital to the resilience of marine communities and sustainability of the worlds oceans. Human influences on marine ecosystems mediate changes in species interactions. This generality is evinced by the cascading effects of overharvesting top predators on the structure and function of marine ecosystems. It follows that ecological forecasting, ecosystem management, and marine spatial planning require a better understanding of food web relationships. Characterising and scaling predator– prey interactions for use in tactical and strategic tools (i.e. multi-species management and ecosystem models) are paramount in this effort. Here, we explore what issues are involved and must be considered to advance the use of predator–prey theory in the context of marine fisheries science. We address pertinent contemporary ecological issues including (1) the approaches and complexities of evaluating predator responses in marine systems; (2) the scaling up of predator–prey interactions to the population, community, and ecosystem level; (3) the role of predator–prey theory in contemporary fisheries and ecosystem modelling approaches; and (4) directions for the future. Our intent is to point out needed research directions that will improve our understanding of predator–prey interactions in the context of the sustainable marine fisheries and ecosystem management.

Multiple lines of evidence suggest that changes in the marine climate in the eastern Bering Sea are leading to numerical and distributional shifts in fish populations that may affect the balance of predatorprey relationships. A rapidly increasing arrowtooth flounder Atheresthes sto- mias population has prompted concern about the growing threat of arrowtooth flounder predation on economically valuable walleye pollock Theragra chalcogramma. The goal of this study was to investigate the overall increasing trend of arrowtooth flounder at a finer spatial resolution to better understand the potential spatial variability in their predatory impact under a changing climate. The specific objectives were to determine whether arrowtooth flounder were increasing equally throughout the eastern Bering Sea and, if not, (1) identify areas with dissimilar abundance trends and (2) explore physical and biological habitat characteristics that may be contributing to these differences. Clustering arrowtooth survey catch per unit effort revealed 4 distinct spatial groups showing stable, increasing, and variable trends. Increasing bottom water temperature and depth were associated with higher proportions of trawls containing arrowtooth and higher catch rates. Age-1 and -2 pollock were the predominant prey in all areas, but higher rates of non-empty stom- achs in the northwest region indicated that current predatory impacts on pollock may be higher there. Favorable physical habitat (deep and warm) and diet trends (full stomachs) suggest that arrowtooth flounder in the northwest region of the eastern Bering Sea have the potential to increase further, perhaps to the abundance levels seen in the high-density area where they may have reached carrying capacity.

Within an established seabird colony the choice of where to settle can be influenced by site fidelity, natal philopatry or public information. To form a new colony individuals must choose before philopatry has been established or public information is available. We explored the intra- colony dynamics of common murres Uria aalge, specifically the formation and persistence of new subcolonies within a larger colony complex composed of numerous contiguous groups. We investi- gated the effects of (1) environmental conditions that influence the prey base, (2) predator distur- bance, and (3) population size change on colonization patterns and modeled the persistence of recently colonized murre subcolonies as a function of their starting population sizes. Marine environ- mental conditions in the 2 winters previous to the breeding season had more influence than demo- graphic and predator factors on whether subcolony colonizations occurred. The number of murres in the first year of colonization helped to explain the persistence of the subcolony, regardless of the amount of available nesting habitat within a subcolony area. Subcolonies that started out larger were more likely to persist. The results support the theory that the proportion of the entire murre popula- tion that attempts to breed in a given year is higher in years with favorable environmental conditions prior to the breeding season. Increased knowledge of murre colony formation may help scientists and managers understand the potential for recolonizations after colony extirpations or better predict the success of management actions such as social attraction or habitat modification.

We conduct a decision analysis that explores the effects of trawl-related fishery mortality on achieving the population recovery goals for the US federally-endangered short-tailed albatross ( Phoebastria albatrus ), proposed by the US Fish and Wildlife Service. A population model is constructed and its parameters estimated using data on counts of the numbers of albatross chicks and eggs at Torishima Island, Japan, where 83% of the world’s population of this species is found. Bayesian inference is used to assign probabilities to alternative plausible rates of fishing mortality and as the basis for population projections with different levels of trawl mortality to determine their effects on achieving the population recovery goals. The analyses of the impact of trawl mortality on the Torishima short-tailed albatross population suggests that exceeding the current expected incidental take in the Alaskan groundfish trawl fishery, two in any 5-year period, by as much as a factor of 10 would have little impact on when the proposed recovery goals for the species are achieved. A quantitative approach that addresses uncertainty, such as that outlined in this study, could aid the process to evaluate allowable limits in light of species recovery goals by addressing both take limits and recovery goals within the same framework.

Spatial and temporal overlap between the short-tailed albatross Phoebastria albatrus, an endangered species, and the Alaskan groundfish trawl fleet is of concern because of the potential for incidental mortality. Due to the small size of this albatross population (ca. 2000 birds) and their wide-ranging foraging behavior, opportunistic sightings contribute the majority of the data on their distribution. In contrast, detailed information exists on fishing effort. In this study, 2 methods were used to predict albatross distributions: (1) bounded interpolation of sightings and (2) distance to the 1000 m isobath. The fishery was grouped into 5 sectors based on fish processing mode and predomi- nant product type. Locations and durations of observed trawls were associated with the predicted albatross densities and overlap was quantified using 2 metrics. Spatial and temporal overlap of alba- trosses and the trawl fleet was influenced by the assumptions used to infer albatross distribution and also differed among trawl sectors depending on the metric used to calculate overlap. The sectors with the highest and lowest overlap changed seasonally. In general, overlap scores were lowest in winter and spring due to both low trawl effort (in winter) and low albatross sightings (winter and spring). Relative effort in trawl sectors, in addition to proximity to high predicted albatross densities, con- tributed to overlap rankings such that some sectors with greater effort in areas with lower predicted albatross density had higher overlap scores than sectors with less effort in areas with high predicted albatross densities.

Coll, Marta ... et al.-- 16 pages, 6 figures, 6 tables, IndiSeas (>Indicators for the Seas>) is a collaborative international working group that was established in 2005 to evaluate the status of exploited marine ecosystems using a suite of indicators in a comparative framework. An initial shortlist of seven ecological indicators was selected to quantify the effects of fishing on the broader ecosystem using several criteria (i.e., ecological meaning, sensitivity to fishing, data availability, management objectives and public awareness). The suite comprised: (i) the inverse coefficient of variation of total biomass of surveyed species, (ii) mean fish length in the surveyed community, (iii) mean maximum life span of surveyed fish species, (iv) proportion of predatory fish in the surveyed community, (v) proportion of under and moderately exploited stocks, (vi) total biomass of surveyed species, and (vii) mean trophic level of the landed catch. In line with the Nagoya Strategic Plan of the Convention on Biological Diversity (2011-2020), we extended this suite to emphasize the broader biodiversity and conservation risks in exploited marine ecosystems. We selected a subset of indicators from a list of empirically based candidate biodiversity indicators initially established based on ecological significance to complement the original IndiSeas indicators. The additional selected indicators were: (viii) mean intrinsic vulnerability index of the fish landed catch, (ix) proportion of non-declining exploited species in the surveyed community, (x) catch-based marine trophic index, and (xi) mean trophic level of the surveyed community. Despite the lack of data in some ecosystems, we also selected (xii) mean trophic level of the modelled community, and (xiii) proportion of discards in the fishery as extra indicators. These additional indicators were examined, along with the initial set of IndiSeas ecological indicators, to evaluate whether adding new biodiversity indicators provided useful additional information to refine our understanding of the status evaluation of 29 exploited marine ecosystems. We used state and trend analyses, and we performed correlation, redundancy and multivariate tests. Existing developments in ecosystem-based fisheries management have largely focused on exploited species. Our study, using mostly fisheries independent survey-based indicators, highlights that biodiversity and conservation-based indicators are complementary to ecological indicators of fishing pressure. Thus, they should be used to provide additional information to evaluate the overall impact of fishing on exploited marine ecosystems. © 2015 Elsevier Ltd. All rights reserved, We thank the Euroceans IndiSeas Working Group funded by the European Network of Excellence EUR-OCEANS (FP6, Contract N° 511106), the European collaborative project MEECE – Marine Ecosystem Evolution in a Changing Environment (FP7, Contract N° 212085) and IRD (Institute of Research for Development) and IOC/UNESCO. [...] MC was partially funded by the European Commission through the Marie Curie Career Integration Grant Fellowships – PCIG10-GA-2011-303534 – to the BIOWEB project and by the Spanish National Program Ramon y Cajal. LJS was supported through the South African Research Chair Initiative, funded through the South African Department of Science and Technology (DST) and administered by the South African National Research Foundation (NRF). LJS and YS were also funded by the European collaborative project MEECE – Marine Ecosystem Evolution in a Changing Environment – (FP7, Contract N° 212085). KMK was supported by the Northeast Fisheries Science Center and the Nature Conservancy through a grant from the Gordon and Betty Moore Foundation. MJJJ was supported by an EU Marie Curie International Outgoing Fellowship – PIOF-GA-2013-628116. MFB was supported by the Portuguese Oceanic and Atmospheric Institute and the trawl survey data collected under Biological Sampling (PNAB) Program. LJG would like to thank the Joint Research Centre of the European Commission for support. HO was financed by the Estonian Ministry of Education and Research (Grant SF0180005s10). JJH was supported by the Natural Environment Research Council and Department for Environment, Food and Rural Affairs [Grant Number NE/L003279/1, Marine Ecosystems Research Programme]. GIvdM was supported by the Institute of Marine Research, Norway. KT was partially funded by the project PERSEUS (Policy-oriented marine Environmental Research in the Southern EUropean Seas; FP7 Contract N° 287600). MAT was funded by the Spanish Institute of Oceanography (IEO) through a Predoctoral FPI fellowship. KNM was supported by a National Research Council fellowship at the Northwest Fishery Science Center. YJS and MTT were partially supported by the French project EMIBIOS (FRB, Contract No. APP-SCEN-2010-II). Chatham Rise trawl survey data were provided by the Ministry for Primary Industries. CL acknowledges DEVOTES – Development of innovative tools for understanding marine biodiversity and assessing good Environmental Status – EC project (FP7 Grant Agreement 308392)

We would like to thank the IndiSeas Working Group, endorsed by IOC-UNESCO (www.ioc-unesco.org) and the European Network of Excellence Euroceans (www.eur-oceans.eu). KMK was supported by Conservation International and the Sea Around Us project, a collaboration between The University of British Columbia and The Pew Charitable Trusts. MC was partially supported by the EC Marie Curie CIG grant to BIOWEB and the Spanish Research Program Ramon y Cajal. LJS was supported through the South African Research Chair Initiative, funded through the South African Department of Science and Technology (DST) and administered by the South African National Research Foundation (NRF). YJS and MIT were supported by the French project EMIBIOS (FRB, contract no. APP-SCEN-2010-11). US and YS were also funded by the European collaborative project MEECE - Marine Ecosystem Evolution in a Changing Environment - (FP7, Contract no. 212085). CPL was supported by Defra project MF1228 (From Physics to Fisheries) and DEVOTES (DEVelopment of innovative Tools for understanding marine biodiversity and assessing good Environmental Status) funded by EU FP7 (grant Agreement no. 308392), www.devotes-project.eu. GIvdM was partially supported by the Norwegian Nature Index programme and the Institute of Marine Research, Norway. HO was funded was funded by the Estonian Ministry of Education and Research (grant SF0180005s10). MAT was funded by a predoctoral FPI fellowship from the Spanish Institute of Oceanography (IEO). MJJJ was supported by the EC Marie Curie IOF Grant, PIOF-GA-2013-628116. We acknowledge all those who conducted surveys to collect the data used in this study.; Fisheries provide critical provisioning services, especially given increasing human population. Understanding where marine communities are declining provides an indication of ecosystems of concern and highlights potential conflicts between seafood provisioning from wild fisheries and other ecosystem services. Here we use the nonparametric statistic, Kendall's tau, to assess trends in biomass of exploited marine species across a range of ecosystems. The proportion of 'Non-Declining Exploited Species' (NDES) is compared among ecosystems and to three community-level indicators that provide a gauge of the ability of a marine ecosystem to function both in provisioning and as a regulating service: survey-based mean trophic level, proportion of predatory fish, and mean life span. In some ecosystems, NDES corresponds to states and temporal trajectories of the community indicators, indicating deteriorating conditions in both the exploited community and in the overall community. However differences illustrate the necessity of using multiple ecological indicators to reflect the state of the ecosystem. For each ecosystem, we discuss patterns in NDES with respect to the community-level indicators and present results in the context of ecosystem-specific drivers. We conclude that using NDES requires context-specific supporting information in order to provide guidance within a management framework. (C) 2015 Elsevier B.V. All rights reserved.

We developed an individual-based model to study the effects of different regimes of harvesting eggs and natural predation on reproductive success in a colony of the glaucous-winged gull (Larus glaucescens) in Glacier Bay National Park, Alaska. The model incorporates the sequence of egg laying, relaying, and incubation to hatching for individual nests and calculates hatching success, incubation length, and the total number of eggs laid (as a result of re-nesting and relaying) in all nests in the colony. Stochasticity is incorporated in the distribution of nest lay dates, predation rates, and nests attacked during predation and harvest events. We estimated parameter values by fitting the model to data collected at a small colony during 1999 and 2000 using maximum likelihood. We then simulated harvests and analyzed model predictions. Model outputs indicate that harvesting early, and at one time, provides a predictable take of eggs with the least impact to gulls.

Bottom-up control, or physical forcing of upper trophic populations, is often cited as a major factor regulating marine species. In particular, seabirds are often cited as indicators of relative productivity and health of the marine environment. The degree to which physical forcing plays a dominant role and the mechanisms of effect remain unclear. We test the relationship between measures of oceanographic and atmospheric forcing, proxied by commonly available monthly to daily indices, and the response of populations of a ubiquitous seabird of the Pacific Northwest coastal environment, the common murre,Uria aalge. We constructed two models: an annualized bottom-up model that examines the degree to which population response variables, including population size, breeding success, and foraging parameters, are correlated with oceanographic forcing at space and time scales relevant to murre biology; and a daily direct forcing model that examines the degree to which diet choices reflect specific, local oceanographic signals. Our bottom-up model suggests that murres are regulated by bottom-up forcing, and that the strength of the association between physical change and population response may be mediated by density dependence. Our direct forcing model indicated that chick diet is affected by both local and remote parameters, including upwelling, tide, and the Pacific Decadal Oscillation. We conclude that murres, and seabirds in general, can be used as indicators of local to basinwide physical change, but only under certain conditions: the life history of the species, and the specific local population, must be well known; a conceptual model that links life history traits to measures of physical change at biologically relevant space and time scales must be developed; and larger populations that are more apt to show density-dependent effects should be selected.

Die Herstellung der porösen metallischen Papiere erfolgt durch eine Kombination von Papiertechnologie und Sintertechnologie. Als Ausgangsmaterialien werden Metallpulver oder Metallfasern sowie Holz und Zellstoffe in einer Flüssigkeit miteinander gemischt. Sie werden danach mit einem sogenannten Blattbildner bzw. mittels einer Papiermaschine zu einem flächigen Werkstoff verarbeitet. Die Verdichtungseigenschaften hängen besonders von Mischungsverhältnis, Partikelform, Partikelgrößenverteilung und interpartikuläre Reibung ab Typischerweise liegt der Metallpulvergehalt zwischen 75 % und 85 %. Es können auch Mischungen aus Metallpulver und Metallfasern eingesetzt werden, wodurch die Gesamtporosität, die Porengröße und das resultierende Flächengewicht variiert werden können. Grundsätzlich können Metallpulver mit Partikelgrößen im Durchmesserbereich zwischen ca. 2 µm und 50 µm zu Papieren verarbeitet werden. Auch ein gradierter Aufbau, d. h. ein Aufbau mit unterschiedlich großen Metallpulverpartikeln durch zusätzliche Beschichtungen ist möglich. Bisher wurden poröse metallische Papiere mit einer Dicke im Bereich von 0,1 mm bis 1 mm hergestellt. Bei der Entbinderung zwischen 200 °C und 650 °C werden der Zellstoff und andere organische Bestandteile in einem thermischen Prozess entfernt. Bei der Sinterung, die bei Edelstahl zwischen 1050 °C und 1300 °C stattfindet, kommt es durch Diffusionsprozesse zur stofflichen Verbindung zwischen den Pulverteilchen bzw. den Metallfasern, welche der porösen Struktur eine hohe Festigkeit verleihen. Es wurden bisher Papiere mit einer mittleren Porengröße im Bereich von 2 µm bis 40 µm und mit einem Flächengewicht zwischen 450 g/m2 und 2000 g/m2 hergestellt. Das Papier kann vor der Wärmebehandlung mit konventionellen Papiertechnologien einfach weitererarbeitet werden kann. Es kann gerollt, gewickelt, gefaltet, gekreppt und geriffelt werden. Es zeigte sich, dass die feinere, offenporigere Struktur bei einer niedrigeren Herstellungstemperatur von Probe A bessere Filtrationseigenschaften aufweist, als die bei einer höheren Temperatur hergestellten Proben (Probe B und C). Das Porensystem ist bei der Probe A weiter verzweigt und weist dadurch eine bessere Partikelabscheidung und eine höhere Permeabilität auf. Im Gegensatz zu den anderen beiden Materialien werden beim Sintermaterial A deutlich mehr Partikeln bereits an der Oberfläche abgeschieden, besonders bei größeren Partikeln ab ca. 10 µm. Auch die Sinterpapiere B und C entfernen Partikeln ab dieser Größe nahezu vollständig. Insgesamt weisen alle Sinterpapiere eine gute Abscheidung gegenüber ISO-Medium-Test-Dust auf. Partikeln ab einer Größe von ca. 8 µm werden von allen Materialien nahezu vollständig abgeschieden, kleinere Partikeln nur teilweise. Die Sinterpapiere scheiden Partikeln sowohl an ihrer Oberfläche als auch im Inneren ab. Eine niedrige Sintertemperatur führt zu einer Struktur mit einem feinen, offenen Porensystem. Daraus resultieren ein geringer Durchströmungswiderstand und eine bessere Abscheidung. Eine Erhöhung der Sintertemperatur lässt diese feine Struktur zunehmend verschmelzen. Das Porensystem weist weniger aber dafür größere Poren auf. Daraus resultieren ein höherer Durchströmungswiderstand und eine schlechtere Abscheidung. Eine Erhöhung der Flächenmasse bzw. Materialdicke führt zu einer besseren Abscheidung und einem erhöhten Durchströmungswiderstand. Die hohe Porosität und die dünne und stabile Struktur der Sinterpapiere sind beste Voraussetzungen zum Einsatz als Filtermedium sowohl für Gase auch als für Flüssigkeiten. Ab ca. 250 °C wird die Auswahl an Filtermedien deutlich eingeschränkt, so dass sich ab diesem Temperaturbereich die spezifischen Vorteile der metallischen Filterpapiere zum Tragen kommen. Die gesinterten Vliese können prinzipiell aus unterschiedlichen Metallen hergestellt werden. So können poröse metallische Papiere aus Chrom-Nickel-Stahl, FeCrAl, Nickelbasis-Legierungen und auch aus Kupferwerkstoffen gefertigtwerden. Bisherige Ergebnisse haben gezeigt, dass sowohl bei schockartigen Druckbeanspruchungen als auch bei Thermowechselbeanspruchen eine gute Performance nachgewiesen werden konnte. Darüber hinaus lassen sie sich löten und schweißen.

We observed Common Murres (Uria aalge) at two breeding sites in lower Cook Inlet, Alaska, to determine whether food availability was reflected in their time-budgets at each colony. Catches of forage fish in nets and relative biomass were greater around a murre colony that has been increasing for the past 25 years than around a colony that has been decreasing over the same time period. Murres spent much more time loafing' on their breeding ledges at the increasing colony, particularly during the incubation period and during evening hours. However, there was little or no difference between colonies in chick feeding rates, chick growth rates, or productivity. It appears that murres at the declining colony devote more time to foraging and have less discretionary time ashore. Because this had little apparent affect on their ability to feed and rear chicks, the population decline must be due to other factors. In any case, attendance time-budgets provide a more sensitive index of food availability than other breeding parameters at murre colonies.

Within this paper the development of 3D woven wire structures in cellular design for multifunctional multi component-composite semi-finished products for economically efficient and resource-conserving processing into hybrid lightweight constructions is described. These structures can be produced in a modified weaving process and are supplied for subsequent processing such as joining and heat treatment. The developed 3D woven wire structures are predestined for the use in lightweight structures due to their high geometric variability, adjustable mechanical properties, and temperature-resistance at a low specific weight. The structures are used as core material in sandwich construction or reinforcing material in metal matrix composites. By combining such wire structures with carbon fibers, a new class of material especially suitable for infiltration with metal matrix can be realized with outstanding high mechanical properties such as good impact and crash resistance as we ll as a high flexibility regarding the choice of materials and optimized structural design. Experimental investigations of mechanical properties and the failure behavior of textile based metal sandwiches and metal-matrix-composites with wire reinforcement have been carried out. For this purpose, extensive static and dynamic tests have been performed. The mechanical properties are compared to commercial lightweight materials of the same class as a benchmark.

Metal hollow spheres (MHS) and metal hollow sphere structures are special types of cellular metals with an enormous application potential in structural and functional applications. A lot of effort has been made during the last two decades in order to develop the manufacturing process and to investigate the properties of this type of structure. Additional functionalizing of MHS is possible by filling the spheres with ceramic powders or phase change materials. Furthermore, by coating the spheres with different ceramic layers new properties and functions are added. Thus, the structures show excellent mechanical damping properties as well as high heat capacity for thermal storage and fast heat loading and unloading. Grinding or ceramic coating bring more functions to the surface of the spheres. The manufacture and properties of different types of functionalized MHS and their possible applications are highlighted here.

Magnesium alloys offer excellent properties with regard to application as degradable implant. For bone implants, it is often desirable to use porous materials. However, the preparation of high-porosity magnesium implants has been difficult so far. The present study uses melt extracted magnesium fibers as the starting material for the sintering of highly porous magnesium bodies, i.e., from alloys MgY4 (W4) and MgY2Zn1CaMn (WZ21). Single short fibers of these alloys with an equivalent diameter between 100 and 250 µm and a length of 4-8 mm are manufactured by melt extraction. Thermodynamic calculations are used to determine the best conditions for liquid phase sintering of these Mg alloys. As no organic or other substances are needed in the process, it is possible to obtain high-purity, high-porosity (up to 75%) bodies with exclusively open porosity. Metallographic studies as well as mechanical and corrosion testing experiments complete this work.

Two types of new cellular metals are fabricated by assembling layer by layer helically-formed wires with MHS (metal hollow sphere) arrays. In the finished configuration, the MHSs are located in small tetrahedrons or octahedrons of the inner space of a WBK (wire-woven bulk Kagome) structure. Compression tests reveal excellent energy absorption, which is attributed to combination of suppression of strut buckling in the WBK and moving plastic hinge occurring in the MHSs. The WBK-MHS hybrids outperform competitors in deformation energy absorption.

Die Erfindung betrifft eine Vorrichtung und ein Verfahren zur Herstellung metallischer Fasern durch Schmelzextraktion. Es können unterschiedliche Metalle oder deren Legierungen zu Fasern mit vorgebbaren Faserdurchmessern und Faserlängen hergestellt werden. Dabei ist es Aufgabe der Erfindung die Effektivität der Faserherstellung zu erhöhen und die Nachteile der Schmelzextraktion aus einer in einem Tiegel vorgehaltenen Schmelze zu vermeiden. Erfindungsgemäß wird mindestens eine radial äußere Kante einer rotierenden durch linienförmig ausgebildete Schmelze an einem Substrat geführt. Die lienienförmige Schmelze wird an einem stirnseitigen Rand eines metallischen Subtrates, das nachführbar ist, induktiv ausgebildet.

Ultra-light materials with open, periodic cell structures are studied by many scientists, because of their potential multi-functionality. Our research group invented the new cellular metal named WBK, fabricated with helical forming wires, and has investigated the performance of the WBK. It has been found that WBK fails by buckling of struts composing WBK. Therefore, for enhancing the resistance against buckling, this work suggests a new idea, that is WBK comprising metal hollow spheres (MHSs) in the inner space, which is named WBK-MHS hybrids. The reason of selecting MHS is that, it also had ultra light weight and high energy absorption. The compressive properties of WBK-MHS hybrid have been investigated and compared to other competitive structures. From the result, the maximum stress and energy absorption are much enhanced in comparison with simple addition of those of the corresponding stand-alone WBK and MHS. The result is attributed to suppression of buckling of struts composing WBK and uniforms deformation over the entire components. The WBK-MHS hybrids out performs competitors in the mechanical performance. Its means Hybrid WBK can widely apply to industry just like car impact bar, bumper and so on.

Es werden auf Basis von zellularen metallischen Werkstoffen deren Vorteile beschrieben. Neben einer drastischen Gewichts- und damit Materialeinsparung können durch zellulare Werkstoffe weitere anwendungsspezifische Eigenschaften, die insbesondere durch die Zellstruktur bestimmt werden, wie Schallabsorption, Wärmeisolation, Energieabsorption, mechanische Dämpfung, Stoff- und Energietransport oder katalytische Effekte, realisiert werden. Zellulare metallische Werkstoffe können aus der flussigen, festen oder gasformigen Phase hergestellt werden. Am weitesten entwickelt sind derzeit die schmelzmetallurgischen Verfahren. Die Herstellung von metallischen Hohlkugeln erfolgt durch Metallpulverbeschichtung von vorwiegend organischen Trägerwerkstoffen (vorzugsweise Styroporkugeln) mit einem anschließenden Entbinderungs- bzw. Sintervorgang. Mit der entwickelten Technologie ist es möglich nahezu alle sinterbaren Pulver als Hohlkugeln (Durchmesserbereich ca. 1-12mm) herzustellen. Die Eigenschaften zellularer metallischer Werkstoffe werden im Wesentlichen durch den Basiswerkstoff sowie die Zellgröße, Zellmorphologie und die Gesamtporosität beeinflusst. Grundsätzlich skalieren die meisten Eigenschaften mit der Gesamtporosität der zellularen Struktur. Die bisher vorliegenden Untersuchungsergebnisse zeigen das zellulare Metalle vor allem ein gutes Energieabsorptionsvermögen, eine sehr gute Schallabsorption sowie gute Wärmedämmeigenschaften besitzen. So zeigten Untersuchungen zum Wärmeleitvermögen von Molybdän-Hohlkugelstrukturen bei einer Strukturdichte von 0,3 g/cm(exp 3) ca. 1 % des Wärmeleitfähigkeit vom kompakten Molybdän. Hierdurch eröffnen sich effizientere Möglichkeiten, z.B. durch die selbsttragenden Eigenschaften der Hohlkugelstrukturen für die Hochtemperaturisolation.

Zu den zellularen metallischen Werkstoffen gehören offenporige und geschlossenporige Metallschäume, metallische Hohlkugel- und Faserstrukturen und im Verbundguß gefertigte Materialien. Diesen zellularen Strukturen ist gemeinsam, daß sie eine Vielzahl nützlicher, anwendungsgerechter Eigenschaften haben. Hervorzuheben sind die geringe Dichte, das hohe Energieadsorptionsvermögen (Schall, Stoß) und günstige dynamische Eigenschaften. Sie sind neue multifunktionale Leichtbauwerkstoffe. Die zellularen metallischen Werkstoffe lassen sich in Form von Blöcken, Platten, Sandwiches und 3D-Bauteilen herstellen. Zum Fügen eignen sich Kleben, Schrauben und auch Schweißen. Geschlossenporige Metallschäume werden durch ein pulvermetallurgisches Verfahren in mehreren Prozeßstufen hergestellt. In einem ersten Schritt wird das metallische Basispulver (z.B. Aluminium) mit einem Treibmittelpulver (z.B. TiH2) vermischt. Anschließend wird das Pulvergemisch zu Blöcken mittels Einstempel-Axialpressens vorkompaktiert. Die nahezu 100 %ige Verdichtung der vorkompaktierten Blöcke erfolgt durch Strangpressen. Das gefertigte schäumbare strangförmige Vormaterial kann durch Walzen, Biegen und Trennen weiter bearbeitet werden. Mit dem schäumbaren Vormaterial werden Schäumformen oder auszuschäumende Bauteile bestückt. Durch eine Wärmebehandlung erfolgt das Schäumen. Die Herstellung von metallischen Hohlkugeln (1 bis 12 mm Durchmesser) erfolgt durch Metallpulverbeschichtung von vorwiegend organischen Trägerwerkstoffen (z.B. Styroporkugeln) mit einem anschließendem Entbinderungs- bzw. Sintervorgang. Die zur Herstellung von Faserstrukturen benötigten Metallfasern werden nach dem Schmelzextraktionsverfahren gewonnen. Hierbei taucht eine wassergekühlte Cu-basierte Extraktionswalze, die an der Außenseite V-förmige Kanten besitzt, in die Oberfläche einer Schmelze. Durch die Benetzung der Schmelze mit der Extraktionskante sowie Rotation der Walze werden zunächst dünne Schmelzfäden gebildet, die durch den schnellen Wärmeentzug erstarren. Diese Fasern haben einen Durchmesser von 50 bis 300 Mikrometer. Durch eine spezielle Faseraufbereitungs und Deponiertechnik mit einem anschließenden Sinterschritt sind Platten, Ringe, Rohre und spezielle Formkörper herstellbar. Die offenporigen Metallschäume werden durch ein modifiziertes Feingießverfahren hergestellt. Offenporige Metallschäume können aus verschiedenen Legierungen und mit unterschiedlichen Porositäten (10 bis 45 ppi) in Form von Platten und Zylindern gefertigt werden. Das Walzverdichten von Metallpulvern zu Flacherzeugnissen ist ein Prozeß, bei dem man in einem Verfahrensschritt Grünbänder erzeugen kann. Dabei ist eine vertikale Zufuhr des Metallpulvers zum Walzspalt vorteilhaft. Angegeben werden technische Daten einer Pulver-Walzverdichtungsanlage. Verbundwerkstoffe aus einem Leichtmetall und Mineralkeramik werden durch Gießverfahren hergestellt. (Sandguss, Niederdruck-Sandguss, Feinguss und Kokilenguss). Für die genannten zellularen metallischen Werkstoffe werden einige Fertigungsbeispiele vorgestellt.

Aufgabe der Erfindung ist es, eine Beruhigung des Schmelzbades und des sich an der Walzenschneide ausbildenden Meniskus zu erreichen, um auf diese Weise den Schmelzextraktionsprozeß zu stabilisieren und die reproduzierbare Herstellung speziell von dünnen Fasern mit Durchmessern unterhalb 100 mm zu ermöglichen. Die statistische Verteilung des Durchmessers der produzierten Fasern um den durch die Prozeßparameter vorgegebenen mittleren Faserdurchmesser soll möglichst schmal sein.