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  • Chemical Engineering  (22)
  • Analytical Chemistry and Spectroscopy  (21)
  • zooplankton  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Dispersal-limited zooplankton distribution and community composition in new ponds (1995)
    Springer
    Hydrobiologia 313-314 (1995), S. 15-20 
    Details
    ISSN: 1573-5117
    Keywords: colonization ; rotifers ; zooplankton ; vagility ; dispersal ; metapopulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twelve new experimental ponds were constructed identically, filled simultaneously, had similar physical and chemical properties, and were maintained with minimal manipulation. Colonizing zooplankton communities were sampled bi-weekly for one year. Rotifers dominated zooplankton communities in densities, biomass, and species number (47 of 61 observed species were rotifers). Only 14 species were observed in all 12 ponds; 9 were rotifers. Twenty-nine species (26 rotifers) were recorded in 〈-6 ponds. Species with high vagility exhibited greater viability. Ponds differed in zooplankton community composition throughout the year, due to differences in both vagility and viability among colonizing species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025926
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Modelling Spatio-Temporal Effects of Environment on Atlantic Herring, Clupea harengus (2000)
    Springer
    Environmental biology of fishes 58 (2000), S. 157-172 
    Details
    ISSN: 1573-5133
    Keywords: generalized additive models ; acoustics ; pelagic ; oceanography ; zooplankton ; North Sea ; abundance ; distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Trends in mean abundance of North Sea Atlantic herring, Clupea harengus, over the period of 1992–1995, were modelled as a function of spatial location and ocean environmental conditions using generalized additive models (GAM). In all four years, the average herring abundance was found to be highest in latitudes around 60.5°N, and decreased with increasing latitude. The thermocline depth had a significant effect on prespawning herring abundance both directly, as a main effect, and indirectly, through its interactive effect with the temperature at 60 m. Average herring abundance was highest in areas having deeper thermocline depths (up to 45 m) and temperatures at 60 m between 9 and 11°C. Prespawning herring abundance was greater in areas of cooler surface waters in the south than in the north. Well-mixed waters and transition zones between frontal and stratified areas having sea surface temperatures mainly between 11 and 12°C and to a lesser extent between 13 and 14°C were associated with the highest herring abundance. Herring appeared to avoid the cold bottom waters in summer. Multiyear GAM analysis revealed consistent environmental preferenda of herring and affirmed further a significant decrease in herring abundance. As herring numbers declined, the population aggregated in the most preferred areas. The inter-relationships of herring and environmental factors across the study period, were similar in their structure and significance, suggesting that preferred areas for location of herring can be reasonably predicted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007693732571
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Zooplankton may not disperse readily in wind, rain, or waterfowl (1998)
    Springer
    Hydrobiologia 387-388 (1998), S. 15-21 
    Details
    ISSN: 1573-5117
    Keywords: Rotifera ; zooplankton ; dispersal ; colonization ; wind ; rain ; waterfowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton, and especially rotifers, have long been thought to be readily dispersed by wind, rain and animals (especially waterfowl). Given that premise, local processes (tolerance to abiotic conditions, biotic interactions) have been the main focus of ecological studies. We tested the premise of high dispersal rates by incubating particulates collected with windsocks and rain samplers at two sites over 1 year. The sites were 80 km apart and differed in proximity to water and surrounding terrain. We also incubated fecal material of wild ducks. Pond sediments were identically incubated as a test of incubation method. Only bdelloid rotifers were collected in wind samples, and only four rotifer species were collected in rain samples: Lecane leontina, Lecane closterocerca, Keratella cochlearis, and a bdelloid. No metazoans were found in incubated duck feces, yet incubated pond sediments yielded 11 rotifer, one copepod, four cladoceran, and three ostracod species. Our results do not support the premise of readily dispersed zooplankton. If zooplankton dispersal is infrequent and limited to few species, a series of other questions should be addressed on processes regulating zooplankton population dynamics and community composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017080029317
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of processes regulating zooplankton assemblages in new freshwater pools (1998)
    Springer
    Hydrobiologia 387-388 (1998), S. 207-214 
    Details
    ISSN: 1573-5117
    Keywords: zooplankton ; rotifers ; colonization history ; disturbance ; nutrient enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the relative importance of colonization history to other known regulators of freshwater zooplankton assemblages (i.e. disturbance and nutrient enrichment) during this six-month study of initial colonization in artificial freshwater pools. We experimentally manipulated 16 small (1.5 m diameter) pools for permanence (permanent vs. temporary) and resource availability (± nitrogen & phosphorus). Nitrogen and phosphorus were added to high resource level pools in concentrations typical of eutrophic waters, while low resource level pools did not receive added nutrients. Permanent pools were maintained with added tap water and temporary pools dried out naturally for one month. Zooplankton colonization was limited to only 10 rotifers (species of Brachionus, Cephalodella, Lecane, Lepadella, Rotaria, and Trichocerca) and 2 crustaceans. Treatments significantly affected physical-chemical variables, colonization curves (species richness through time), and mean cumulative species number. Results indicate that local conditions (habitat permanence and resource availability) had the greatest effect on zooplankton species richness. However, low species diversity and little treatment effect on species relative abundance patterns suggest that colonization history (dispersal) was also important. Therefore, colonization history and local conditions were jointly responsible for structuring zooplankton assemblages in this study. Colonization history may have lasting effects on zooplankton composition in older, natural systems as well, but may be overlooked at some scales of measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017093810178
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Zooplankton may not disperse readily in wind, rain, or waterfowl (1998)
    Springer
    Hydrobiologia 287-388 (1998), S. 15-21 
    Details
    ISSN: 1573-5117
    Keywords: Rotifera ; zooplankton ; dispersal ; colonization ; wind ; rain ; waterfowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton, and especially rotifers, have long been thought to be readily dispersed by wind, rain and animals (especially waterfowl). Given that premise, local processes (tolerance to abiotic conditions, biotic interactions) have been the main focus of ecological studies. We tested the premise of high dispersal rates by incubating particulates collected with windsocks and rain samplers at two sites over 1 year. The sites were 80 km apart and differed in proximity to water and surrounding terrain. We also incubated fecal material of wild ducks. Pond sediments were identically incubated as a test of incubation method. Only bdelloid rotifers were collected in wind samples, and only four rotifer species were collected in rain samples: Lecane leontina, Lecane closterocerca, Keratella cochlearis, and a bdelloid. No metazoans were found in incubated duck feces, yet incubated pond sediments yielded 11 rotifer, one copepod, four cladoceran, and three ostracod species. Our results do not support the premise of readily dispersed zooplankton. If zooplankton dispersal is infrequent and limited to few species, a series of other questions should be addressed on processes regulating zooplankton population dynamics and community composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017080029317
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    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Comparison of processes regulating zooplankton assemblages in new freshwater pools (1998)
    Springer
    Hydrobiologia 287-388 (1998), S. 207-214 
    Details
    ISSN: 1573-5117
    Keywords: zooplankton ; rotifers ; colonization history ; disturbance ; nutrient enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the relative importance of colonization history to other known regulators of freshwater zooplankton assemblages (i.e. disturbance and nutrient enrichment) during this six-month study of initial colonization in artificial freshwater pools. We experimentally manipulated 16 small (1.5 m diameter) pools for permanence (permanent vs. temporary) and resource availability (± nitrogen & phosphorus). Nitrogen and phosphorus were added to high resource level pools in concentrations typical of eutrophic waters, while low resource level pools did not receive added nutrients. Permanent pools were maintained with added tap water and temporary pools dried out naturally for one month. Zooplankton colonization was limited to only 10 rotifers (species of Brachionus, Cephalodella, Lecane, Lepadella, Rotaria, and Trichocerca) and 2 crustaceans. Treatments significantly affected physical-chemical variables, colonization curves (species richness through time), and mean cumulative species number. Results indicate that local conditions (habitat permanence and resource availability) had the greatest effect on zooplankton species richness. However, low species diversity and little treatment effect on species relative abundance patterns suggest that colonization history (dispersal) was also important. Therefore, colonization history and local conditions were jointly responsible for structuring zooplankton assemblages in this study. Colonization history may have lasting effects on zooplankton composition in older, natural systems as well, but may be overlooked at some scales of measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017093810178
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Direct measurement of dietary fractional absorption using calcium isotopic tracers (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 603-607 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fractional dietary Ca absorption, ‘a’, is measured by determining the ratio of two stable isotopic tracers, one of them orally (44Ca @ 0.2-0.5 mg/kg) and the other intravenously (42Ca @ 0.02-0.1 mg/kg). Thermal ionization mass spectrometry (TIMS) is used to measure the perturbation of natural abundance isotope ratios (delta % excess). Typical sensitivity of the TIMS permits detection of a 2.5 delta % excess change from the natural Ca isotope ratio with relative standard deviations of about 0.5%. At sufficiently long times absorption becomes constant so that ‘a’ is determined by a product of constants and a measured ratio.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200141105
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Substituent effects in the mass spectrometry of 4-substituted camphors studied under electron and chemical ionization (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 876-880 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The electron ionization mass spectra of fourteen 4-substituted (4-X) camphors have been recorded and analyzed using metastable ion analysis and exact mass measurement. With respect to camphor, alkyl substituents changed the relative importance of different fragmentation pathways, though they did not induce new fragmentations. Substituents X connected to the camphor framework through an atom having a lone pair of electrons were generally lost as HX. Overall the fragmentation behaviour was essentially independent of the inductive substituent constant. Under chemical ionization conditions, only methane of the reagent gases produced extensive fragmentations of these compounds; isobutane, acetone and ammonia were ineffective. The nature of the fragmentations was independent of both the inductive substituent constant of the substituent X and the proton affinity and heat of formation of the corresponding neutral compound HX.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290081104
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and use of a novel chiral surfactant based on (R,R)-tartaric acid and its application to chiral separations in micellar electrokinetic capillary chromatography (MECC)Presented at the 17th International Symposium on Capillary Chromatography and Electrophoresis, Wintergreen, Virginia, USA, May 1995 (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 7 (1995), S. 513-520 
    Details
    ISSN: 1040-7685
    Keywords: chiral ; separation ; micellar ; capillary ; electrophoresis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article describes the synthesis of a novel chiral surfactant based on (R,R)-tartaric acid. (R,R)-Tartaric acid is acetylated while simultaneously forming a cyclic anhydride, which is then reacted with n-decylamine forming a chiral, long chain carboxylic acid. This carboxylic acid is then further reacted with the achiral amino acid taurine forming the required surfactant which has a sulfonic acid headgroup. Evidence for its surface activity and an estimate of its critical micelle concentration (cmc) have been obtained using surface tension measurements and conductivity. The surfactant has then been used as the additive in micellar electrokinetic capillary chromatography (MECC) to achieve chiral separations of compounds with multiple aromatic functionality. These separations are compared with those achieved with previously reported tartaric acid based surfactants which show a difference in selectivity. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220070512
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Direct observation of a DNA quadruplex by electrospray ionization mass spectrometry (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 181-183 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In 10 mM sodium phosphate, pH 7.6, containing 0.1 mM ethylenediaminetetraacetic acid, ions corresponding to the non-covalent, four-stranded oligonucleotide, d(CGCG4GCG)4, were detected by negative ion electrospray ionization (ESI) mass spectrometry at a low nozzle-skimmer (ΔNS) bias (-150 V), but not at a higher ΔNS bias (〉 -250 V). In contrast, when the sample was desalted and analyzed by ESI mass spectrometry at a low ΔNS bias only ions for the single-stranded d(CGCG4GCG) species were observed. These data agree with spectroscopic evidence which showed that oligonucleotides with the sequence motif 5′d(CGCGnGCG)3′, where n = 2-5, formed stable four-stranded complexes in the presence of monatomic cations, like K+, Ca2+, Na+ and Li+, but not in their absence.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200220307
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