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  • 1
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    Altered complementary feeding strategies of the consumers Hydrobia ulvae and Idotea emarginata via passive selectivity. (2009)
    In:  EPIC3Helgoland Marine Research 63 (3), pp. 189-197
    Details
    Publication Date: 2018-02-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    Selectivity and competition between two benthic invertebrate grazers (Asellus aquaticus and Potamopyrgus antipodarum): an experimental study using 13C- and 15N-labelled diatoms (2005)
    In:  EPIC3Freshwater biology, 50, pp. 369-379
    Details
    Publication Date: 2018-02-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
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    Selectivity and competitive interactions between two benthic herbivores - an experimental study using 13C- and 15N-labelled diatoms. (2004)
    In:  EPIC3ASLO Summer Meeting, 14.06.04, Savannah, USA.
    Details
    Publication Date: 2018-02-16
    Description: Tracer experiments with two diatoms labelled with 13C (Nitzschia palea) and 15N (Fragilaria crotonensis), respectively, were conducted to investigate feeding selectivity and interspecific competition between the herbivore grazers Asellus aquaticus (Isopoda, Crustacea) and Potamopyrgus antipodarum (Hydrobiidae, Gastropoda). Traditional methods such as cell counts and biovolume calculations revealed a similar significant decrease in algal biovolume for all different grazer treatments. In contrast, measurements on isotope signatures showed large differences in tracer uptake and different degrees of assimilation. Thus, this technique enabled the direct quantification of the grazers uptake and assimilation and therefore served as an ideal tool for the detection of passive selectivity. Our results indicate a shift in feeding preferences related to between-species competition and a potential divergence of trophic niches through competitive interactions. Furthermore, this presented study will examine the potential role of passive vs. active selection in marine and freshwater food-webs.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 4
    Electronic Resource
    Electronic Resource
    The Defect in the Magnetic Susceptibility of Manganese Dioxide and Other Compounds of Manganese1 (1946)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 68 (1946), S. 605-608 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01208a022
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    FS04.6
Dose/unit area and time – key factors influencing the elicitation capacity of MCI/MI (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc.
    Contact dermatitis 50 (2004), S. 0 
    Details
    ISSN: 1600-0536
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The objective of the study was to investigate, using the Repeated Open Application Test (ROAT), two key parameters of exposure – allergen concentration (dose/unit area) and time in terms of the elicitation capacity of methylchloroisothiazolinone and methylisothiazolinone (MCI/MI) in MCI/MI-sensitised individuals and to explore the inter-relationship between these two key factors. The study was designed as a double-blind, placebo-controlled, dose-response ROAT preceded by a Diagnostic Patch Test (DPT). 79 patients with a known MCI/M allergy were contacted, 29 were diagnostically patch tested and 25 had their allergy confirmed. 25 MCI/M-allergic subjects and 10 healthy non-allergic control subjects were challenged with 2 ppm of MCI/MI/unit area of skin for 4 weeks. After a wash out period of at least 4 weeks the subjects were challenged with 7.5 ppm of MCI/MI/unit area of skin for 4 weeks. A ROAT with 2 drops of solution twice a day was conducted on the volar aspect of the left and right forearms on a 3 × 3 cm area resulting in dose/unit area of MCI/MI of 0.025 mg/cm2 and 0.095 mg/cm2 for 2 ppm and 7,5 ppm MCI/MI respectively. The elicitation capacity of MCI/MI in MCI/MI sensitive patients is dependent on the exposure dose/unit area and time The results of this study will be a useful addition to the risk assessment information available for MCI/MI. The risk assessment for the use of MCI/MI in rinse off consumer products is unaffected by the results of this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0105-1873.2004.0309ao.x
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  • 6
    Electronic Resource
    Electronic Resource
    Selectivity and competitive interactions between two benthic invertebrate grazers (Asellus aquaticus and Potamopyrgus antipodarum): an experimental study using 13C- and 15N-labelled diatoms (2005)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 50 (2005), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Tracer experiments with two diatoms labelled with 13C (Nitzschia palea) and 15N (Fragilaria crotonensis), were conducted to investigate feeding selectivity and interspecific competition between the grazers Asellus aquaticus (Isopoda, Crustacea) and Potamopyrgus antipodarum (Hydrobiidae, Gastropoda). Conventional methods, such as cell counts and estimated biovolume, were used first to detect feeding preferences within the different grazer treatments.2. The results revealed a significant decline in algal biovolume in all grazer treatments and no indications of active selectivity were observed. In contrast to conventional methods, measurements based on isotope signatures showed strong differences in tracer uptake, thus indicating different degrees of assimilation and digestion by the two grazers.3. The selectivity index Q, which provides information on the uptake ratio of 13C to 15N, showed a significant time effect for both grazer species and a significant difference between single- and mixed-grazer treatments for P. antipodarum. Thus, this technique enabled the direct quantification of the uptake by grazers and, therefore, served as an ideal tool for the detection of passive selectivity.4. Our results indicate a shift in feeding preferences related to between-species competition and a potential divergence of trophic niches when species coexist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01325.x
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  • 7
    Electronic Resource
    Electronic Resource
    Ferox Trout (Salmo trutta) as `Russian dolls': complementary gut content and stable isotope analyses of the Loch Ness foodweb (2002)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 47 (2002), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Conventional collection methods for pelagic fish species (netting, trawling) are impractical or prohibited in Loch Ness, U.K. To investigate trophic relationships at the top of the Loch Ness food web, an alternative strategy, angling, provided samples of the top predator, the purely piscivorous ferox trout (Salmo trutta).2. The gut contents of these fish provided further samples of prey-fish, and subsequent examination of prey-fish guts revealed their dietary intake, analogous to the famous nested `Russian dolls'. Each trophic level separated by gut content analysis provided further complementary samples for stable isotope analysis and thus information on the longer term, assimilated diet.3. Ferox trout exhibited considerable cannibalism to supplement a diet of Arctic charr (Salvelinus alpinus). However, conspecifics stemmed from a lower isotopic baseline in relation to charr, so ferox trout exhibited a lower trophic level than predicted (4.3) by using the δ15N values. Charr displayed dietary specialisation with increasing length, and isotopic values supported by the gut data placed the charr at a trophic level of 3.5. The isotope data also indicated that charr carbon was primarily autochthonous in origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2002.00838.x
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  • 8
    Electronic Resource
    Electronic Resource
    Zooplankton interactions in an enclosure experiment: insights from stable isotope analyses (2004)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 49 (2004), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Density gradients of cladocerans and copepods were generated in an enclosure experiment to compare the impact on the plankton of a filter feeder (Daphnia hyalina × galeata) with that of more selective feeders (calanoid and cyclopoid copepods). The experiment was conducted in situ over 25 days during spring in a mesotrophic lake, Schöhsee, Germany.2. The plankton community was monitored regularly. Daphniids were able to graze on the phytoplankton present, which mainly consisted of small (〈1000 μm3) species, whereas copepods did not show any impact on algae.3. At the end of the experiment, Daphnia and remaining cyclopoid copepods were harvested and sorted manually, prior to analyses for stable isotopes of carbon and nitrogen. Daphniids from mesocosms stocked purely with differing densities of Daphnia showed little variability in stable isotope values, whereas those that thrived in enclosure bags together with copepods exhibited lower δ13C values.4. The change in Daphniaδ13C indicates a change of food sources, modified by the presence of the copepods: the higher the mean abundance of copepods in the enclosures, the more 13C-depleted the daphniids. Increasing abundance of high nucleic acid (HNA) bacteria in the copepod bags may account for the trend in Daphniaδ13C via increased grazing on the bacteria themselves, or via grazing on phytoplankton utilising isotopically light CO2 from respiratory release.5. Cyclopoid copepod stable isotope signatures were related to Daphnia and copepod abundances in copepod bags, suggesting that cyclopoids preyed on the available zooplankton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.2004.01283.x
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  • 9
    Electronic Resource
    Electronic Resource
    Ontogeny and dietary specialization in brown trout (Salmo trutta L.) from Loch Ness, Scotland, examined using stable isotopes of carbon and nitrogen (2001)
    Copenhagen : Munksgaard International Publishers
    Ecology of freshwater fish 10 (2001), S. 0 
    Details
    ISSN: 1600-0633
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract – The trophic ecology of many fish species in cold temperate lakes is often characterized by a generalist or opportunist strategy. In this study, the diets of polytrophic brown trout in Loch Ness, Scotland, have been examined using stable isotopes of carbon and nitrogen to complement gut content analyses and aging by otolith annuli counts. Using the stable isotope ratios, it was possible to trace trout ontogeny from parr development in a natal river to piscivory in the pelagic. Potential dilution of maternal isotope signatures from eggs to parr was also demonstrated. Despite the low productivity of the loch, intraspecific variability in isotope ratios suggested dietary specialization, rather than opportunism, in some individuals./〉
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0633.2001.100306.x
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  • 10
    Electronic Resource
    Electronic Resource
    A Pseudo-Aurora (1911)
    [s.l.] : Nature Publishing Group
    Nature 87 (1911), S. 347-347 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE explanation which Sir Lauder Brunton calls for in No. 2183 of NATURE seems to be very simple indeed. On the evening of August 21, which he mentions, thunderstorms of extreme violence came over the region of Lugano and its environs. That region is due south-east of Beatenberg, as is also the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/087347a0
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