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Maier M.,Alfred Wegener Institute for Polar and Marine Research | Siegel D.,Institute for Marine Resources GmbH | Thoben K.-D.,University of Bremen | Niebuhr N.,Institute for Marine Resources GmbH | Hamm C.,Alfred Wegener Institute for Polar and Marine Research
Journal of Bionic Engineering | Year: 2013

The abstraction of complex biological lightweight structure features into a producible technical component is a fundamental step within the transfer of design principles from nature to technical lightweight solutions. A major obstacle for the transfer of natural lightweight structures to technical solutions is their peculiar geometry. Since natural lightweight structures possess irregularities and often have extremely complex forms due to elaborate growth processes, it is usually necessary to simplify their design principles. This step of simplification/abstraction has been used in different biomimetic methods, but so far, it has an arbitrary component, i.e. it crucially depends on the competence of the person who executes the abstraction. This paper describes a new method for abstraction and specialization of natural micro structures for technical lightweight components. The new method generates stable lightweight design principles by using topology optimization within a design space of preselected biological archetypes such as diatoms or radiolarian. The resulting solutions are adapted to the technical load cases and production processes, can be created in a large variety, and may be further optimized e.g. by using parametric optimization. © 2013 Jilin University.


Friedrichs L.,Alfred Wegener Institute for Polar and Marine Research | Hornig M.,Alfred Wegener Institute for Polar and Marine Research | Schulze L.,Alfred Wegener Institute for Polar and Marine Research | Bertram A.,Alfred Wegener Institute for Polar and Marine Research | And 3 more authors.
Marine Ecology Progress Series | Year: 2013

Diatoms are encased within sophisticated stable lightweight silica cell walls. These frustules have the potential to protect the algal cell against the feeding tools of their most abundant metazoan predators, the copepods. We examined the mechanical strengths of the 3 North Sea diatom species Actinoptychus senarius, Thalassiosira punctigera and Coscinodiscus wailesii and their effect on feeding efficiency of copepods. (1) We determined the stability of the diatoms by means of 'micro-crush-tests' performed in the laboratory with calibrated microneedles. (2) In feeding experiments, we compared the ability and efficiency of the 3 North Sea copepod species Temora longicornis, Centropages hamatus and Acartia clausi to crush frustules. The results showed a remarkable correlation between mechanical properties and size of diatom frustules and feeding success of the copepods. The weakly silicified diatom T. punctigera was the least stable and best fed upon, whilst having the highest growth rate. The diatoms having the most complex frustule, A. senarius, exhibited the greatest stability, whilst being fed upon least. The largest diatom, C. wailesii, was partially protected by its size, but was nonetheless suitable as prey for the large copepods that, in the case of C. hamatus, seem to have developed special feeding techniques to overcome the size-mediated protection. © Inter-Research 2013.


Seemann U.B.,Institute for Marine Resources GmbH | Seemann U.B.,Alfred Wegener Institute for Polar and Marine Research | Lorkowski K.,Institute for Marine Resources GmbH | Lorkowski K.,Alfred Wegener Institute for Polar and Marine Research | And 8 more authors.
Freshwater Crayfish | Year: 2014

There is growing interest in using recirculating aquaculture systems (RAS) to produce juvenile noble crayfish, Astacus astacus (Linnaeus), a valuable and once plentiful food species in Europe, now a highly endangered species. The survival rates of early stripped eggs of A. astacus were compared across anti-fungal treatments in an artificial RAS incubation system based on a saline bath of approx. 20 - 22 mS cm-1 or 15 - 16 PSU over two different durations. Time from fertilisation to hatching was 82 days or 1191 degreedays. Low survival rates (live successfully hatched juveniles at end of experimental period) between 11.0 ± 9.5% and 26.6 ± 3.7% were obtained. Survival was significantly affected by the duration of egg bath within the saline solution with twice as high survival rates when eggs were saline-bathed once every two days for five minutes in comparison to eggs without treatment. Fungal rates were significantly affected by treating the eggs with a saline solution with infection rates decreasing from 3.7 ± 1.0% to 0.8 ± 0.5% in the ten minute saline bath treatment. Appropriately applied saline bathing can markedly improve survival of early-stripped noble crayfish eggs. However, further research is required to determine whether viable levels of hatching success can be obtained using early stripping and saline treatment. Copyright © 2014 by The Author(s).


Seemann U.B.,Institute for Marine Resources GmbH | Seemann U.B.,Alfred Wegener Institute for Polar and Marine Research | Lorkowski K.,Bremerhaven University of Applied Sciences | Lorkowski K.,Alfred Wegener Institute for Polar and Marine Research | And 5 more authors.
Aquaculture International | Year: 2015

There is growing interest in using recirculating aquaculture systems (RAS) to raise noble crayfish Astacus astacus a valuable and once plentiful food species in Europe, now a highly endangered species. The growth and survival of A. astacus was compared in growth trials in RAS and open-pond systems (OPS) over a period of 2 months. Energy and lipid content of available diets and crayfish tissue were also determined. Growth of A. astacus during summer was significantly (p < 0.01, one sample t test) higher in OPS (SGR 1.23) than in RAS even at the highest feeding ration provided at 5 % bw/d−1 (RAS HI SGR 0.78 ± 0.06). OPS crayfish also had significantly (p < 0.01 OPS vs. all RAS treatments; Pairwise Wilcoxon) higher lipid content (8.51 %) than RAS crayfish (RAS HI 5.73 %, RAS MED 6.93 %, RAS LOW 5.92 %). Survival rates in RAS were, however, 100 % compared with previous observations in OPS of approx. 70 %. While results showed OPS growth exceeds than that in RAS in the short term, RAS survival rates and annualized growth performance may outweigh this disadvantage, particularly if optimal artificial diets for RAS holding are provided. Feed and crayfish analysis indicated that culturing A. astacus in RAS require a diet protein content exceeding 30 % and lipid content of <13 %, indicating that the carp diet supplied was not optimal. RAS culture allows this valuable species to be cultured in controlled, disease-free enclosed systems—resulting in high-value food products as well as high-quality seedlings for restocking purpose. © 2014, Springer International Publishing Switzerland.


Fuchs V.I.,University of Veterinary Medicine Hannover | Schmidt J.,Institute for Marine Resources GmbH | Schmidt J.,Alfred Wegener Institute for Polar and Marine Research | Slater M.J.,Institute for Marine Resources GmbH | And 5 more authors.
Aquaculture | Year: 2015

The investigation and application of a wide range of dietary supplements, such as probiotics, prebiotic and other additives, are increasingly popular in aquaculture research and practice. To date few studies have attempted to quantify the value of commercially available additives in improving growth performance of juvenile turbot (. Scophthalmus maximus) and in compensating potential growth reduction resulting from high levels of plant protein (PP) in carnivorous fish diets.Two experiments were conducted to investigate the effect of different active ingredients in diet additives on turbot. I) Five diets supplemented with (1) yeast b-glucan and mannan oligosaccharides (GM), (2) alginic acid from brown algal extracts (AC), (3) yeast nucleotides and RNA (NR), (4) potassium diformate (PDF) and (5) bacteria strains Bacillus subtilis and B. licheniformis (BS), containing fish meal (FM) as the only protein source, were fed to turbots (initial weight 48.8. g. ±. 5.2. g) over 112. days. II) Four diets supplemented with (1) GM, (2) AC, (3) NR and (4) BS, containing soy protein concentrate (SPC) and wheat gluten (WG) as a partial replacement of FM, were fed to turbots (initial weight 95.8. g. ±. 17.7. g) over 84. days. A non-supplemented FM diet (exp. I) and an FM- and PP-based diet (exp. II), respectively, were used as control diets.Diet additives did not promote additional weight gain, specific growth rate (SGR), daily feed intake (DFI) and feed conversion ratio (FCR) in turbot fed FM- or PP-based diets (p. >. 0.05) when compared to isocaloric control diets in both experiments. Growth of turbots fed the high FM content control diet (II) was significantly higher than all other treatments (p. <. 0.01). Body proximate composition, condition factor (K) and liver index (HSI) remained unaffected by additive supplementation in fish fed either FM or PP diets (p. >. 0.05).Results indicate that reported benefits for specific diet additives cannot be assumed to function or applied across species boundaries and age classes. In addition, dietary additive application may not be economically valid for larger animals and/or animals not exposed to specific culture-related stressors. The benefits of popular additives to high value species such as S. maximus remains to be tested under specific immune or physical stress situations and at crucial larval and early juvenile stages. © 2014 Elsevier B.V.


Slater M.J.,Northumbria University | Slater M.J.,Institute for Marine Resources GmbH | Mgaya Y.D.,University of Dar es Salaam | Stead S.M.,Northumbria University
PLoS ONE | Year: 2014

Finding effective solutions to manage marine resources is high on political and conservation agendas worldwide. This is made more urgent by the rate of increase in the human population and concomitant resource pressures in coastal areas. This paper links empirical socio-economic data about perceptions of marine resource health to the breaking of marine management rules, using fisheries as a case study. The relationship between perceived rule-breaking (non-compliance with regulations controlling fishing) and perceived health of inshore marine environments was investigated through face-to-face interviews with 299 heads of households in three Tanzanian coastal communities in November and December 2011. Awareness of rules controlling fishing activity was high among all respondents. Fishers were able to describe more specific rules controlling fishing practices than non-fishers (t = 3.5, df = 297, p<0.01). Perceived breaking of fishing regulations was reported by nearly half of all respondents, saying "some" (32% of responses) or "most" (15% of responses) people break fishing rules. Ordinal regression modelling revealed a significant linkage (z = 23.44, p<0.001) in the relationship between respondents' perceptions of deteriorating marine health and their perception of increased rule-breaking. In this paper, inferences from an empirical study are used to identify and argue the potential for using perceptions of ecosystem health and level of rule-breaking as a means to guide management measures. When considering different management options (e.g. Marine Protected Areas), policy makers are advised to take account of and utilise likely egoistic or altruistic decision-making factors used by fishers to determine their marine activities. © 2014 Slater et al.


Friedrichs L.,Alfred Wegener Institute for Polar and Marine Research | Maier M.,Institute for Marine Resources GmbH | Hamm C.,Alfred Wegener Institute for Polar and Marine Research | Hamm C.,Institute for Marine Resources GmbH
Journal of Microscopy | Year: 2012

Exact geometric description, numerical analysis and comparison of microscopic objects such as the frustules of diatoms are of increasing importance in basic research (e.g. functional morphology, taxonomy and biogeochemistry). Similarly, applied research and product development in the fields of lightweight construction and nanotechnology can benefit from machine-readable data of such structures. This paper presents a new method to combine data from scanning electron microscopy and confocal laser scanning microscopy to generate exact three-dimensional models of diatom frustules. We propose a method to obtain a high-quality mesh for subsequent analysis through finite element analysis, for example, for biomechanical research on diatom frustules. A specific lightweight value as a universal tool to describe and compare the biomechanical quality of microscopic objects is introduced. Our approach improves the precision of three-dimensional reconstructions, but the generation of usable finite element meshes from complex three-dimensional data based on microscopic techniques requires either a transformation of grid points into elements or smoothing algorithms. Biomechanical analyses of differently obtained models indicate that more complex three-dimensional reconstructions lead to more realistic results. © 2012 The Authors Journal of Microscopy © 2012 Royal Microscopical Society.


Wever L.,Institute for Marine Resources GmbH | Krause G.,Alfred Wegener Institute for Polar and Marine Research | Buck B.H.,Alfred Wegener Institute for Polar and Marine Research | Buck B.H.,Bremerhaven University of Applied Sciences
Marine Policy | Year: 2015

Drawing on a case study in Germany, this contribution explores the practical application of offshore aquaculture within offshore wind farms in view of the different stakeholders involved. Using a transdisciplinary research approach, an understanding of the rationalities and interests among the different involved stakeholder groups was explored. Offshore wind energy is high on the political agenda in Germany. The vast spatial requirements however inherit potential user conflicts with competing, and under current legislation excluded users such as fishermen. Solutions for combining sustainable uses of the same ocean space have thus seen increasing interest within the research community in Germany and in Europe over the past years. This paper was inspired by and presents the outcomes of a stakeholder analysis and in particular a stakeholder workshop. Central focus was placed on academics and private as well as public stakeholders engaged in current research efforts of combining offshore wind farms and aquaculture in the German North Sea. The paper identifies the overall acceptance of such a multi-use scenario in society, opportunities and constraints as perceived by the stakeholders, and key research gaps. The results confirm the assumption that there is a clear need, and also willingness on behalf of the policy makers and the research community, to find sustainable, resource- and space-efficient solutions for combined ocean use. © 2014 Elsevier Ltd.


Freese D.,Alfred Wegener Institute for Polar and Marine Research | Schewe I.,Alfred Wegener Institute for Polar and Marine Research | Kanzog C.,Institute for Marine Resources GmbH | Soltwedel T.,Alfred Wegener Institute for Polar and Marine Research | Klages M.,Alfred Wegener Institute for Polar and Marine Research
Polar Biology | Year: 2012

Commercial exploitation and abrupt changes of the natural conditions may have severe impacts on the Arctic deep-sea ecosystem. The present recolonisation experiment mimicked a situation after a catastrophic disturbance (e. g. by turbidites caused by destabilised continental slopes after methane hydrate decomposition) and investigated whether the recolonisation of a deep-sea habitat by meiobenthic organisms is fostered by variations in nutrition and/or sediment structure. Two "Sediment Tray Free Vehicles" were deployed for 1 year in summer 2003 at 2,500 m water depth in the Arctic deep-sea in the eastern Fram Strait. The recolonisation trays were filled with different artificial and natural sediment types (glass beads, sand, sediment mixture, pure deep-sea sediment) and were enriched with various types of food (algae, yeast, fish). After 1 year, meiobenthos abundances and various sediment-related environmental parameters were investigated. Foraminifera were generally the most successful group: they dominated all treatments and accounted for about 87 % of the total meiobenthos. Colonising meiobenthos specimens were generally smaller compared to those in the surrounding deep-sea sediment, suggesting an active recolonisation by juveniles. Although experimental treatments with fine-grained, algae-enriched sediment showed abundances closest to natural conditions, the results suggest that food availability was the main determining factor for a successful recolonisation by meiobenthos, and the structure of recolonised sediments was shown to have a subordinate influence. © 2012 Springer-Verlag.

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