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  • 1
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    Cambridge University Press
    In:  New York, 475 pp., Cambridge University Press, vol. 26, no. ALEX(01)-FR-77-01, AFTAC Contract F08606-76-C-0025, pp. 329, (ISBN 0-521-62434-7 hc (0-521-62478-9 pb))
    Publikationsdatum: 1999
    Schlagwort(e): Textbook of geophysics ; Seismology ; traditional ; Udias
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  • 2
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    Wiley
    In:  New York - 2nd ed., 372 pp., Wiley, vol. 1, pp. 225, (ISBN 0-471-32192-3)
    Publikationsdatum: 1999
    Schlagwort(e): Textbook of geography ; Textbook of informatics ; GIS
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  • 3
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    Cambridge University Press
    In:  New York, 260 pp., Cambridge University Press, vol. Developments in Petroleum Science vol. 15B, no. Publ. No. 12, pp. 9, (ISBN 0-521-66023-8 hc (0-521-66953-7 pb))
    Publikationsdatum: 1999
    Schlagwort(e): Textbook of geophysics ; Seismology ; modern
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  • 4
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    Wiley
    In:  Journal of Ecology, 87 (3). pp. 503-513.
    Publikationsdatum: 2017-07-18
    Beschreibung: 1 Zonation is often seen in environments with a strong physico-chemical gradient, such as salt marshes. It has been hypothesized that plant species are limited in their distribution by abiotic factors towards the more extreme end of the gradient, and by competition towards the more favourable end. Invasion of the native clonal grass genus Elymus in many Wadden Sea marshes may be due to increasing atmospheric nitrogen input into a nitrogen-limited environment. However, at Thmlauer Bay, Germany, Elymus athericus does not occur in lower salt marsh communities that are dominated by a dwarf shrub (Atriplex portulacoides). We therefore hypothesized that at this site the downslope (= more extreme) distributional boundary of E. athericus is a result of competition with A. portulacoides rather than of physiological limits. 2 A factorial experiment was set up to investigate the effects of removal of each competitor and fertilization. The reciprocal effects of the species on each other were measured in terms of vegetation cover and above-ground biomass. The impact of the tidal regime on plant zonation was investigated by calculating inundation frequencies at the boundary between the two plant populations from water level recordings. 3 Elymus athericus extended its distribution into the lower salt marsh when A. portulacoides was removed. The latter increased in cover but not in biomass after the removal of E. athericus. Neither species showed a response to nitrogen fertilization. The boundary between the two species in the control plots varied considerably in elevation and inundation frequency. 4 The lower distributional boundary of E. athericus can be interpreted as the result of competition with A. portulacoides. Improvement of nitrogen availability in concentrations of the same order of magnitude as annual atmospheric input had no detectable effect on plant zonation and growth. Elevation and inundation frequency were not strictly correlated with plant zonation.
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  • 5
    Publikationsdatum: 2019-09-23
    Beschreibung: Heavy mineral studies of East Siberian river sediments, Laptev Sea surface sediments, and a sediment core of the western Laptev Sea were carried out in order to reconstruct the pathways of modern and ancient sediment transport from the Siberian hinterland to the Laptev Sea. The modern heavy mineral distribution of Laptev Sea surface sediments reflects mainly the riverine input. While the eastern and central part of the Laptev Sea is dominated by amphibole, which is supplied by the Lena River, the western part is dominated by pyroxene imported from the Siberian Trap basalts by the Khatanga River. The distribution of garnet and opaque minerals is additionally influenced by hydrodynamic processes. As a consequence of their high density, these minerals are predominantly deposited close to the river mouths. Heavy mineral and sedimentological studies of a sediment core of the western Laptev Sea were applied to reconstruct the postglacial history of the shelf area during the last 11 ka. In the lowermost interval of the core (〉c. 10 ka), high accumulation rates and a heavy mineral composition similar to that of the modern Khatanga river indicate fluvial conditions. Additionally, the high mica content in this interval may indicate meltwater inflow from the Byrranga mountains. Strong variations in accumulation rates, grain-size distribution, and heavy mineral composition are observed in the time interval between c. 10 and 6 ka, which represents the main transgression of the Laptev Sea shelf. During the uppermost interval (〈6 ka), rather stable conditions similar to the modem situation prevailed.
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  • 6
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    Wiley
    In:  International Review of Hydrobiology, 84 (2). pp. 119-128.
    Publikationsdatum: 2018-06-29
    Beschreibung: The influence of mixing frequency and depth on phytoplankton functional group composition (mobile versus immobile species) was studied by enclosure experiments in a shallow, stratified lake. Mixing events were artificially induced at intervals from 2–12 d. The mixing depth was increased from the natural level (4 m) to 6 and 9 m. The mobile phytoplankton in the experiments consisted of cyanobacteria and flagellates. Among the latter, large and rapid swimming species were represented by dinoflagellates. An increase of the relative abundance of gas vacuolated cyanobacteria occurred with increasing frequency of mixing. Additionally Reynolds' hypothesis predicting the occurrence of certain mobile phytoplankton genera in response to the mixing regime could be confirmed for the condition when mixing depth exceeds the euphoric depth.
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  • 7
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    Association of Field Ornithologists | Wiley
    In:  Journal of Field Ornithology, 70 (1). pp. 28-32.
    Publikationsdatum: 2019-08-08
    Beschreibung: Ship speed may have an important effect on the results of seabird surveys. We counted seabirds on a 20.5 X 0.3 km transect in the Kattegat that was sailed nine times with the RV "Heincke." Ship speed alternated between 9 knots and 5 knots. The numbers of the most common species, the Lesser Black-backed Gull (Larusfuscus), were significantly higher when the ship was sailing at lower speed similar to that of commercial fishing vessel when trawling in the area. It is postulated that scavenging species( e.g., gulls) are attracte to the low speed of vessels whereas non-scavengers (e.g. auks) are not
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  • 8
    Publikationsdatum: 2020-02-18
    Beschreibung: The identification of developmental stages in fish eggs from plankton samples is often complicated by deformation of the embryos due to mechanical stress during the sampling procedure and by dehydration during formaldehyde fixation. The effects of formaldehyde fixation and mechanical stress on Baltic cod eggs (Gadus morhua callarias L.) were examined separately by visually comparing the morphological features of treated vs. live eggs of identical ontogenetic age. Microphotographs were made concurrently for documentation. In stage IA eggs, mechanical treatment resulted in scattered blastodiscs surrounded by single cells, while in further advanced stages the yolk membrane collapsed entirely, the yolk coagulated and the embryo extending over the yolk shrank. Formaldehyde fixation caused the yolk and the blastodisc or embryo to darken, and in some cases crystalline enclosures occurred. Eggs mechanically deformed during handling were clearly distinguishable from those that died prior to catching; however, staging was generally less accurate for formaldehyde-preserved eggs when compared with living specimens.
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  • 9
    Publikationsdatum: 2019-09-23
    Beschreibung: The holocene depositional setting of the Laptev Sea was studied using three marine sediment cores from water depths between 77 and 46 m. Based on sedimentary parameters (TOC content, delta(13)C(org) Sedimentation rates) controlled by radiocarbon age models the palaeoenvironment of a strongly coupled river-shelf system was reconstructed since similar to 11 ka SP. Caused by a transgressing sea after the last glaciation, all cores reveal progressive decreases in sedimentation rates. Using the sedimentary records of a core from the Khatanga-Anabar river channel in the western Laptev Sea, several phases of change are recognized: (1) an early period lasted until similar to 10 ka BP characterized by an increased deposition of plant debris due to shelf erosion and fluvial runoff; (2) a transitional phase with consistently increasing marine conditions until 6 ka BP, which was marked at its beginning near 10 ka BP by the first occurrence of marine bivalves, high TOC content and an increase in delta(13)C(org); (3) a time of extremely slow deposition of sediments, commencing at,6 ka BP and interpreted as Holocene sea-level highstand, which caused a southward retreat of the depositional centres within the now submerged river channels on the shelf; (4) a final phase with the establishment of modern conditions after similar to 2 ka BP.
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  • 10
    Publikationsdatum: 2020-07-20
    Beschreibung: The growth of Fucus vesiculosus L, germlings in chemically defined culture media containing a range of Cu concentrations (20-1000 nM) was monitored simultaneously with measurement of the Cu speciation in the media by competitive equilibrium-adsorptive cathodic stripping voltammetry, Fucus vesiculosus germlings were found to exude Cu-complexing Ligands with conditional stability constants of the order of 1.6 x 10(11), Ligand concentrations increased with increasing total dissolved Cu concentrations (Cu-T) until a concentration of 500-800 neq Cu.L-1 was reached. Concentrations of the ligand exceeded Cu-T in treatments containing 20 and 100 nM Cu-T were similar to Cu-T in the 500-nM Cu treatment, but were less than Cu-T in the 1000-nM treatment. Therefore, [Cu2+] were calculated to be at concentrations of 10(-11) - 10(-10) M in the 20- and 100-nM treatments, 10(-9) M in the 500-nM treatment, and 10(-7) M in the 1000-nM treatment, Growth rates were lowest at Cu2+ concentration 〉 10(-9). These results are discussed within the context of the potential roles for exuded copper-complexing ligands
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  • 11
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    Wiley
    In:  Journal of Applied Ichthyology, 15 . pp. 224-227.
    Publikationsdatum: 2017-06-16
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  • 12
    Publikationsdatum: 2017-06-16
    Beschreibung: The aim of this study was to evaluate the potential of a compound diet as a live prey substitute for feeding European sea bass larvae (Dicentrarchus labrax L.). The effect of a commercial diet (Nippai ML feed) and live prey (Artemia nauplii) on tryptic enzyme activity, protein content, growth (standard length) and survival rates of sea bass larvae were tested during a 27-day rearing experiment. Sea bass larvae were divided into two groups. The live food group (control group) was fed exclusively on newly hatched Artemia nauplii (Inve AF grade), the test group was fed exclusively with the compound diet from day 15 onwards. As trypsin has been demonstrated to be a useful indicator for evaluating digestibility of food and the nutritional condition of fish larvae, individual tryptic enzyme activity was determined in both feeding groups. Larvae older than 14 days after hatching and fed on live food showed a significantly higher tryptic enzyme activity than larvae fed the compound diet. A similar relationship between tryptic activity and standard length in both test groups was detected only in small larvae (standard length 〈 7 mm). The usefulness of proteolytic enzyme activity measurements in larval fish research, as well as its use in aquaculture nutrition research, was confirmed. Protein content, increase in length and survival rates of the sea bass larvae were additionally determined in order to evaluate an influence on the diet. The protein content of larvae fed the Artemia nauplii was higher and the growth of larvae fed the compound diet was reduced. Larval mortality was not affected by the diet given.
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  • 13
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    Wiley
    In:  Journal of Phycology, 35 . pp. 403-424.
    Publikationsdatum: 2018-06-25
    Beschreibung: Microalgal biovolume is commonly calculated to assess the relative abundance (as biomass or carbon) of co‐occurring algae varying in shape and/or size. However, a standardized set of equations for biovolume calculations from microscopically measured linear dimensions that includes the entire range of microalgal shapes is not available yet. In comparison with automated methods, the use of microscopical measurements allows high taxonomic resolution, up to the species level, and has fewer sources of error. We present a set of geometric shapes and mathematical equations for calculating biovolumes of 〉850 pelagic and benthic marine and freshwater microalgal genera. The equations are designed to minimize the effort of microscopic measurement. The similarities and differences between our proposal for standardization and previously published proposals are discussed and recommendations for quality standards given.
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  • 14
    Publikationsdatum: 2019-03-14
    Beschreibung: We looked at the routes taken by Magellanic Penguins up the beach while moving between the sea and the colony at a breeding site in San Julian, Argentina. Birds swam parallel to the shore for a period before leaving the water to cross the beach but trajectories over the beach were not perpendicular to the water's edge but at an angle of 39°. We examined the premise that birds might be optimizing for a trade off between time or energy by adopting this procedure and found that birds can gain little or no time by walking obliquely but can, under particular circumstances, save energy. These circumstances require that the previously-calculated costs of transport for walking have been over-estimated by a factor of two
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  • 15
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    Wiley
    In:  International Journal for Numerical Methods in Fluids, 29 (8). pp. 899-920.
    Publikationsdatum: 2020-07-28
    Beschreibung: Various discretization methods exist for the numerical simulation of multiphase flow in porous media. In this paper, two methods are introduced and analyzed—a full-upwind Galerkin method which belongs to the classical finite element methods, and a mixed-hybrid finite element method based on an implicit pressure–explicit saturation (IMPES) approach. Both methods are derived from the governing equations of two-phase flow. Their discretization concepts are compared in detail. Their efficiency is discussed using several examples.
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  • 16
    Publikationsdatum: 2019-02-27
    Beschreibung: The germination of spores of the endophytic brown algae Laminariocolax aecidioides and Laminarionema elsbetiae (Ectocarpales sensu lato) on their host Laminaria saccharina was studied using scanning electron microscopy. Zoids were the infective units in both taxa. Despite a large difference in size between spores of the species studied, the initial steps of infection were similar. Zoids settled on the host surface, and during secretion of adhesive material from their anterior end, the spores became elongated to rod-shaped and stood erect on the host. A single germ tube developed at the proximal end and penetrated the intact surface of the host. Sharp edges around the entrance hole and the absence of inward deformation of the host surface around the settled zoids suggest an enzymatic rather than a mechanical penetration mechanism.
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  • 17
    Publikationsdatum: 2019-02-27
    Beschreibung: Coupled three-dimensional (3-D) physical oceanographic modelling and field sampling programmes were carried out in May 1988 and August 1991 to investigate the potential drift of larval cod (Gadus morhua L.) in the Bornholm Basin of the Baltic Sea. The goals were to predict the transport of cod larvae, thus aiding the identification of physical processes influencing larval retention/dispersal. Numerical simulations were performed using a 3-D eddy-resolving baroclinic model based on the Bryan–Cox–Semtner code adapted for the Baltic Sea. Within the Bornholm Basin, the model was initialized with ground truth data of physical parameters obtained on the research cruises, and all simulations were forced with actual wind data. Outside the basin, generalized hydrographic features of the Baltic Sea were utilized by incorporation of simulated hydrographic fields from previous model runs typical for the time periods considered. Larval drift was simulated either by incorporation of passive drifters, or as the initial horizontal distribution of larvae implemented into the model. Drift model simulations of larval transport agreed relatively well with field observations. The influence of variations in the vertical distribution on a smaller scale, i.e. vertical deviations of ± 6 m from the observed mean centre of mass, on the drift was examined, revealing no significant differences in the drift of larvae depending on their vertical distribution. The different wind forcing during the investigated time periods was linked to a retention situation in May 1988 and to a dispersal situation in August 1991. Finally, observed spatial distribution patterns of 1-group cod based on Baltic Young Fish Surveys (BYFS) were compared with their predicted transport in the larval phase and examined with respect to recruitment.
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  • 18
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    Wiley
    In:  Internationale Revue der gesamten Hydrobiologie und Hydrographie, 84 . pp. 271-286.
    Publikationsdatum: 2017-07-03
    Beschreibung: Mesozooplankton production was estimated by using a new sampling technique and two alternative calculation methods. In essence, production estimates are based on significantly higher abundances. The contribution of juvenile stages to copepod and fish dynamics was generally low, so that the omission of juvenile stages in budgets will result in a small error. The situations reported in this study present a unique food web szenario, which in detail, however, was strongly dependent on methodology. Furthermore, relations between trophic levels were considered with respect to vertical distribution.
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  • 19
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    American Medical Society | Wiley
    In:  ChemInform, 47 (9). pp. 1305-1307.
    Publikationsdatum: 2020-07-27
    Beschreibung: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option
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  • 20
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    American Chemical Society
    In:  Journal of Natural Products, 62 (6). pp. 811-816.
    Publikationsdatum: 2020-07-22
    Beschreibung: Two new iridoid glucosides, 6-O-acetylajugol (1) and 7,8-epoxy-8-epi-loganic acid (2), together with five known iridoid glucosides, galiridoside (3), ajugoside (4), 10-deoxygeniposidic acid (5), 7-deoxy-8-epi-loganic acid (6), and 8-O-acetylharpagide (7), have been isolated from the aerial parts of Leonurus persicus. Leucosceptoside A (8), eugenyl β-rutinoside (9), and kaempferol 3-O-glucoside (10) were also isolated. The structures of 1 and 2 were elucidated by extensive 1D- and 2D-NMR spectroscopy and molecular modeling. The structure of 3 was confirmed by single-crystal X-ray diffraction. Antimicrobial activity of compounds (1−10) was also evaluated against a panel of Gram-positive and Gram-negative bacteria and two strains of fungi.
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  • 21
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    Wiley
    In:  Journal of Phycology, 35 (4). pp. 747-755.
    Publikationsdatum: 2018-04-26
    Beschreibung: Gracilaria conferta (Schousboe ex Montagne) J. ct G, Feldmann responded with an oxidative burst and rapid increases in respiration and halogenating activity when agar, agarose, or the agarose degradation products neoagarotetraose and neoagarohexaose were added to the growth medium, In contrast, carrageenan, oligocarrageenans, neoagarobiose, L-galactose, D-galactose, and several other mono- and oligosaccharides did not have any effect, Sixfold increases in respiration were observed 3 min after addition of neoagarohexaose. The response could only be induced in species of the genera Gracilaria and Gracilariopsis. Neoagarohexaose also elicited a release of hydrogen peroxide in less than 15 min, resulting in an immediate increase in algal brominating activity. Bleached thallus tips appeared a few hours after the addition of neoagarohexaose. This effect was dependent on the release of hydrogen peroxide and exposure to light, Exposure to light and oligosaccharide elicitors increased the production of reactive oxygen species, which reached destructive concentrations when both mechanisms were simultaneously active. Concentrations of 0.1 to 3.3 mu M agarose or agars were sufficient to trigger an increase in respiration, an oxidative burst response, and tip bleaching. However, higher concentrations of neoagarohexaose and neoagarotetraose were necessary to elicit the responses, indicating that the alga is more sensitive to oligoagars with degrees of biose-polymerization 〉 3, The extremely short reaction time and high specificity indicate that intermediates of agar degradation are recognized by Gracilaria as messengers when microbial degradation of its cell wall occurs, The physiological responses may represent the early stages of algal defense mechanisms involved in repression of pathogen ingress.
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  • 22
    Publikationsdatum: 2019-09-23
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  • 23
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    Cambridge University Press
    In:  In: Warm climates in earth history. , ed. by Wing, S. L. Cambridge University Press, Cambridge, pp. 275-296. ISBN 9780521641425
    Publikationsdatum: 2018-02-06
    Materialart: Book chapter , NonPeerReviewed
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  • 24
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    Wiley
    In:  Journal of Applied Ecology, 36 (1). pp. 101-110.
    Publikationsdatum: 2021-06-11
    Beschreibung: 1. Monthly series of abundance indexes for the English Channel squid stock, based on fishery statistics of the United Kingdom (1980–93) and France (1986–96), were compared with water temperature data. The two objectives of the study were to test empirical predictive models and to analyse the stock–environment relationship at various time scales; both correlation and time-series statistical techniques were applied. Sea surface temperature (SST) showed inter-annual fluctuations and month-to-month auto-correlation in addition to the annual cycle. 2. Trends in squid landings and temperature at the annual scale were found to be related, whatever the statistical method used (moving averages, cumulative functions or regression using averaged data). 3. Variable selection applied in a ‘multi-month’ model suggested that fishing season indexes could be predicted from temperatures observed in the previous winter. The link between mild winter conditions and cohort success in winter/spring spawning species suggested that early life survival (and/or growth) was involved. This empirical model is a first step in the development of environment-predicted recruitment indexes useful for management advice. 4. Seasonal decomposition was performed on both the squid resource data and SST data in search of short-term relationships. In spite of the flexibility of the loliginid life-cycle, no significant relationship was found between squid seasonally adjusted indexes and temperature anomalies in the previous months. This underlined the conclusion that temperature effect on cohort success was not constant throughout the year.
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  • 25
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 79 (3). pp. 479-486.
    Publikationsdatum: 2021-06-17
    Beschreibung: Stomach contents of Todarodes sagittatus caught by trawlers working from 100 to 800 m depth in the Balearic Sea (western Mediterranean) were studied. From the 348 stomachs examined (153 males and 195 females) 33.62% were empty (39.21% in males and 29.74% in females). The diet of the squid was composed of 58 different prey items belonging to four major groups: Osteichthya, Crustacea, Cephalopoda and Chondrichthya. Osteichthyes, crustaceans and cephalopods were the most common prey, with a frequency of occurrence value of 84.85, 48.92 and 29.87% respectively. A change in the diet as the squid grows was observed, since juveniles feed basically on fishes while adults prey more actively on crustaceans. Analysis of the diet by size-classes reflected an ontogenetic migration to deeper waters since, parallel to the increase of size, a raise in the percentage of prey species inhabiting deeper waters was detected. Cannibalism was quite frequent, since T. sagittatus was the second most common cephalopod prey. Females had higher fullness-weight index and lower emptiness index than males, which reflects their major energetic demand for egg production.
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  • 26
    Publikationsdatum: 2021-06-30
    Beschreibung: A 3 year study of the diets of breeding royal Eudyptes schlegeli and rockhopper E. chrysocome penguins was carried out at two nearby colonies on Macquarie Island. Diets of both species were dominated by euphausiids and myctophid fish, in particular Euphausia vallentini and Krefftichthys anderssoni. Prey items were those found in the region of the Polar Frontal Zone, confirming the importance of this zone to these penguins. Diets of both species before hatching of the chicks were variable between years, and differences in quantity of food brought ashore and degree of digestion of prey suggested inter-annual variation in distribution of prey resources. No dietary differences were detected in either penguin species across the breeding season, which reflected variability in diet at all stages, indicating that individual penguins foraged in separate areas. Significant differences between the two species were found, royal penguins consuming more myctophid fish and rockhopper penguins consuming more euphausiids. Differences were also found in the size class of prey items taken and the degree of digestion of food by both penguin species, indicating that prey were taken from different sectors of the ocean. It is concluded that the overlap in diet is small in individuals from these two spatially close colonies and, contrary to previous studies, indicates a separation in the resources used by both species. The contrast with previous studies is most likely a reflection of the different methods used to assess overlap and, to a lesser extent, the years and colonies in which the comparisons were made.
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  • 27
    Publikationsdatum: 2021-06-24
    Beschreibung: Mastigophora brevipinnis Owen, 1856, is a ‘fossil teuthid’ presently considered to be a member of the coleoid cephalopod Suborder Loligosepiina Jeletzky, which in turn has been placed by various authors in or near the Vampyromorpha Grimpe. Recent morphological and biochemical analyses indicate that vampyromorphs are more closely related to the Octopoda than to the Decapodiformes. Fossils of Mastigophora from the Oxford Clay (Jurassic: Callovian) show soft-tissue preservation and evidence of arm crown specialization. Some of these fossils have up to eight short, thick arms with circular sucker-like structures and filiform distal extensions, plus what appear to be the bases of two thinner ventrolateral arms. The latter lack proximal suckers and curve medially to insert into the arm crown, similar to the tentacles that are the modified ventrolateral arms of living squids and cuttlefishes. This suggests that the thinner structures were decapod-like tentacles. If Mastigophora had tentacles homologous with those of modern decapods, then it was a decapod, because this synapomorphy defines the Decapodiformes. This indication of decapod affinities for Mastigophora brings into question the relationships of the other ‘fossil teuthids’. The inferred relationship of the Loligosepiina, including Mastigophora, with the Vampyromorpha, based largely on similarities of gladius morphology with that of living Vampyroteuthis, may reflect shared plesiomorphic characters.
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  • 28
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 79 (3). pp. 467-477.
    Publikationsdatum: 2021-06-11
    Beschreibung: The population structure of the European flying squid Todarodes sagittatus was studied using data of about 5000 squid caught in waters off the western Sahara between 1969 and 1997. The bulk of the population consisted of winter-spawned squid, which occurred as juveniles of 80–120 mm mantle length (ML) over the slope in spring, and as immature squid of 160–180 mm ML both on the shelf and slope in summer. In autumn, the squid attained 220–280 mm ML, matured, and shifted to the slope, where the spawning was supposed to occur in winter. Age and growth of T. sagittatus was studied using statolith ageing techniques. Assuming daily production of putative growth increments within statoliths, as well as sizes and proportions of immature and maturing females, the lifespan of the west Saharan populations of T. sagittatus lasts ∼1 y. Todarodes sagittatus is a fast growing squid at juvenile and immature ontogenetic phases. Early maturation (at ages 220–230 d in males and 250–260 d in females, respectively) and subsequent decrease of somatic growth rates caused rather small modal sizes of mature squid (250–300 mm ML) compared with those of their northern counterparts (350–420 mm ML). Both hatching dates and seasonality in occurrence of mature females shows that in waters off the western Sahara T. sagittatus spawns throughout the year with a well-pronounced winter peak.
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  • 29
    Publikationsdatum: 2021-07-05
    Beschreibung: Microsatellite DNA markers were applied for the first time in a population genetic study of a cephalopod and compared with previous estimates of genetic differentiation obtained using allozyme and mitochondrial DNA (mtDNA) markers. Levels of genetic variation detected with microsatellites were much higher than found with previous markers (mean number of alleles per locus=10.6, mean expected heterozygosity (HE)=0.79; allozyme HE=0.08; mtDNA restriction fragment length polymorphism (RFLP) HE=0.16). In agreement with previous studies, microsatellites demonstrated genetic uniformity across the population occupying the European shelf seas of the North East Atlantic, and extreme genetic differentiation of the Azores population (RST/FST=0.252/0.245; allozyme FST=0.536; mtDNA FST=0.789). In contrast to other markers, microsatellites detected more subtle, and significant, levels of differentiation between the populations of the North East Atlantic offshore banks (Rockall and Faroes) and the shelf population (RST=0.048 and 0.057). Breakdown of extensive gene flow among these populations is indicated, with hydrographic (water depth) and hydrodynamic (isolating current regimes) factors suggested as possible barriers to migration. The demonstration of genetic subdivision in an abundant, highly mobile marine invertebrate has implications for the interpretation of dispersal and population dynamics, and consequent management, of such a commercially exploited species. Relative levels of differentiation indicated by the three different marker systems, and the use of measures of differentiation (assuming different mutation models), are discussed.
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  • 30
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 79 (3). pp. 569-570.
    Publikationsdatum: 2021-06-11
    Beschreibung: Size of ripe eggs and potential fecundity are described in the squid of the subfamilies Todaropsinae and Todarodinae (Oegopsida: Ommastrephidae)— Todaropsis eblanae from West Africa, Todarodes angolensis from Namibia, Todarodes sagittatus from north-west Africa and the Mediterranean Sea, Todarodes sp. from the south-east Pacific, Nototodarus hawaiiensis from the south-east Pacific and West Indian Ocean and Martialia hyadesi from the south-west Atlantic. Females of both subfamilies are characterized by a wide range of ripe egg size (0.7–2.4 mm) and low and medium values of potential fecundity (20,000–2,500,000).
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  • 31
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    Wiley
    In:  Ecology Letters, 2 (2). pp. 65-69.
    Publikationsdatum: 2017-02-22
    Beschreibung: Benthic microalgae and the herbivores Idothea chelipes (Isopoda) and Littorina littorea (Gastropoda) were used as an experimental model system to study the effect of herbivore type on primary producer diversity. Both herbivores enhanced diversity at intermediate grazing pressures, the enhancing effect being stronger with Littorina. This difference is explained by differences in the spatial heterogeneity of the grazed microalgal biofilm caused by behavioural differences in spatial grazing patterns. Idothea spreads its grazing pressure rather evenly in space (“lawn-mower” type), whereas Littorina creates pronounced spatial heterogeneity by moving slowly over the biofilm and decimating it within the grazing tracks (“bulldozer” type). Idothea grazing did not enhance biomass patchiness beyond the level of ungrazed controls (maximum/minimum from 1.7 to 5.5), whereas Littorina strongly increased patchiness (maximum/minimum from 45 to 850).
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  • 32
    Publikationsdatum: 2018-04-26
    Beschreibung: Despite recognition that Fe availability is significant in regulating oceanic production in some regions, the biogeochemistry of this trace element is poorly understood. To complement contemporary methods of analytical chemistry, we have used an immunological approach to monitor theFenutrition of marine phytoplankton. In prokaryotes and numerous microalgae, the redox catalyst ferredoxin is functionally replaced by flavodoxin during periods of Fe deficiency. In this study, antibodies were raised against ferredoxin purified from a marine diatom, and their utility as a diagnostic indicator was assessed. A species survey demonstrated broad reactivity with both pennate and centric diatoms and additionally with several nondiatom taxa. In batch cultures of the diatom Phaeodactylum tricornutum Bohlin, in which Fe levels were varied, accumulation of ferredoxin varied with the physiological state of the culture; in unimpaired cells (Fv/Fm $ 0.65), ferredoxin levels were high, whereas levels dropped markedly in cells experiencing even slight photochemical impairment. Accumulation of flavodoxin varied inversely with that of ferredoxin. An experiment was performed to demonstrate the temporal pattern of accumulation of ferredoxin upon recovery from Fe limitation. Prior to Fe amendment,cells were physiologically impaired (chlorotic, Fv/Fm , 0.3) and contained flavodoxin but no detectable ferredoxin. Following addition of Fe, constraints on photochemistry were relaxed within hours. Coinciding with this, levels of flavodoxin declined, whereas ferredoxin was accumulated to high levels within 8 h.
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  • 33
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    Oxford University Press
    Publikationsdatum: 2022-02-23
    Beschreibung: Rayleigh fractionation is an important, open system process that involves the progressive removal of a fractional increment of a trace substance from a larger reservoir. A consistent relationship, such as a distribution coefficient, equilibrium constant, or a fractionation factor, is maintained between the reservoir and each increment at the instant of its formation, but, once formed, each increment is thereafter removed or otherwise isolated from the system. The mathematical constraints of this process include the distribution coefficient along with a statement of material balance in the shrinking system. These constraints may be combined into a single differential equation that may be integrated to a well-known relationship discovered by Rayleigh (1902). Examples of this common process include condensation, distillation, and the formation of crystals from a melt or a solution. As shown in the following, Rayleigh fractionation explains many different characteristics of meteoric waters, and provides a first-order explanation of the MWL
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  • 34
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    Cambridge University Press
    In:  The terrestrial biosphere and global change: Implications for natural and managed ecosystems
    Publikationsdatum: 2022-03-21
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  • 35
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    Wiley
    In:  How is ecosystem function affected by the hydrological lateral flows in complex landscapes? | Integrating hydrology, ecosystem dynamics and biogeochemistry in complex landscapes
    Publikationsdatum: 2022-03-21
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  • 36
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    Cambridge University Press
    In:  The terrestrial biosphere and global change: Implications for natural and managed ecosystems
    Publikationsdatum: 2022-03-21
    Materialart: info:eu-repo/semantics/bookPart
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  • 37
    Publikationsdatum: 2024-03-20
    Beschreibung: Periphyton was grown on transparent plastic substrata in the Kiel Fjord and used for short-term laboratory experiments to study the feeding selectivity of the periwinkle Littorina littorea in response to the vertical structure of the periphyton. The susceptibility of algae to periwinkle grazing was assessed by comparing the species-specific biomass within the grazing tracks of the snails to the biomass outside the tracks. After 3 weeks of incubation, the periphyton consisted of a scattered monolayer of algal cells without vertical structure. No apparent grazing could be found. After 6 weeks of incubation, periphyton consisted of a tightly attached undergrowth (mainly Cocconeis scutellum, Bacillariophyceae, and Myrionema sp., Phaeophyceae) and canopy of filamentous (Melosira moniliformis, Bacillariophyceae) and stalked forms (Achnanthes longipes, Bacillariophyceae). The unicellular diatoms Fragilaria tabulata and Stauroneis constricta grew partly on the primary substratum and partly as epiphytes on the canopy species. The canopy species and the epiphytes were decimated inside the grazing tracks, while the tightly attached undergrowth species appeared ungrazed.
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  • 38
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    Wiley
    In:  Chichester, 292 pp., Wiley, vol. 45, pp. ii + 37 pp. + 35 figs. + 4 tabs., (ISBN 0-471-95596-5)
    Publikationsdatum: 1998
    Schlagwort(e): Textbook of informatics ; FTN90 ; Gegenueberstellung ; der ; beiden ; Programmiersprachen ; PIK ; Potsdam
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  • 39
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    American Chemical Society
    In:  The Journal of Organic Chemistry, 63 (26). pp. 10011-10014.
    Publikationsdatum: 2020-05-11
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  • 40
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    American Chemical Society
    In:  Energy & Fuels, 12 (2). pp. 201-211.
    Publikationsdatum: 2018-04-11
    Beschreibung: We describe a new and efficient technique to grow aggregates of pure methane hydrate in quantities suitable for physical and material properties testing. Test specimens were grown under static conditions by combining cold, pressurized CH4 gas with granulated H2O ice, and then warming the reactants to promote the reaction CH4(g) + 6H2O(s→l) → CH4·6H2O (methane hydrate). Hydrate formation evidently occurs at the nascent ice/liquid water interface on ice grain surfaces, and complete reaction was achieved by warming the system above the ice melting point and up to 290 K, at 25−30 MPa, for approximately 8 h. The resulting material is pure, cohesive, polycrystalline methane hydrate with controlled grain size and random orientation. Synthesis conditions placed the H2O ice well above its melting temperature while reaction progressed, yet samples and run records showed no evidence for bulk melting of the unreacted portions of ice grains. Control experiments using Ne, a non-hydrate-forming gas, showed that under otherwise identical conditions, the pressure reduction and latent heat associated with ice melting are easily detectable in our fabrication apparatus. These results suggest that under hydrate-forming conditions, H2O ice can persist metastably to temperatures well above its ordinary melting point while reacting to form hydrate. Direct observations of the hydrate growth process in a small, high-pressure optical cell verified these conclusions and revealed additional details of the hydrate growth process. Methane hydrate samples were then tested in constant-strain-rate deformation experiments at T = 140−200 K, Pc = 50−100 MPa, and ε = 10-4−10-6 s-1. Measurements in both the brittle and ductile fields showed that methane hydrate has measurably different strength than H2O ice, and work hardens to an unusually high degree compared to other ices as well as to most metals and ceramics at high homologous temperatures. This work hardening may be related to a changing stoichiometry under pressure during plastic deformation; X-ray analyses showed that methane hydrate undergoes a process of solid-state disproportionation or exsolution during deformation at conditions well within its conventional stability field.
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  • 41
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    Wiley
    In:  In: Marine botany. Wiley, New York, NY, pp. 45-61. 2. Ed. ISBN 0-471-19208-2
    Publikationsdatum: 2017-07-07
    Beschreibung: The chapter gives an overview of marine plant relationships with their environment, wich is called ecology. The overview is a requirement to understanding the biology of marine plants because they do not live as isolated units. Consideration will be given to basic tenets of marine ecology including levels of organization (Populations to ecosystems), processes of community development (succession, energy transfer), strategies (evolutionary, plant responses), biological iunteractions (forms of symbiosis, competition, predation), and growth (rates and responses).
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  • 42
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (02). pp. 561-575.
    Publikationsdatum: 2020-07-16
    Beschreibung: A total of 57 comparative hauls using a rectangular midwater trawl with a fishing mouth area of 50 m2 (RMT 50) were carried out along the sides of an imaginary triangle south of Madeira in 1986. A total of 1258 cephalopods were caught, giving a mean of 22 per haul with a range from 0 to 67. The nets were used with a diver's light on the top bar which was either switched off or was operated with a 20, 70 or 150 W bulb, powered by a car battery. A significantly greater number of individuals per haul was caught with lights on than without lights, increasing from a mean of 13·5–25·1, a factor of 1·8. Similarly, the number of species caught was increased from a mean of 7 to 10·4, a factor of 1·5 and the volume of cephalopods was increased from a mean of 41·1–162·3ml, a factor of 3·9. Similar comparisons made for catches during day or night separately and on the three courses separately also showed marked increases with the lights. Samples show that increase in power of the lights increased the total number of cephalopod individuals caught. In the 12 species with more than ten individuals, in 33 of the 36 comparisons (of number of individuals, species and volumes) there is an increase with the light. The most influenced species was Taonius pavo which increased in numbers by a mean factor of 3·9 times with 20W, 4·0 times with 70W and 6·1 times with 150W when compared with the numbers caught with no light.
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  • 43
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    American Chemical Society
    In:  Energy & Fuels, 12 (2). pp. 191-196.
    Publikationsdatum: 2020-07-31
    Beschreibung: An overview is provided of time-independent physical/chemical properties as related to crystal structures. The following two points are illustrated in this review:  (1) Physical and chemical properties of structure I (sI) and structure II (sII) hydrates are well-defined; measurements have begun on sH. Properties of sI and sII are determined by the molecular structures, described by three heuristics:  (i) Mechanical properties approximate those of ice, perhaps because hydrates are 85 mol % water. Yet each volume of hydrate may contain as much as 180 volumes (STP) of the hydrate-forming species. (ii) Phase equilibrium is set by the size ratio of guest molecules within host cages, and three-phase (Lw−H−V) equilibrium pressure depends exponentially upon temperature. (iii) Heats of formation are set by the hydrogen-bonded crystals and are reasonably constant within a range of guest sizes. (2) Fundamental research challenges are (a) to routinely measure the hydrate phase (via diffraction, NMR, Raman, etc.), and (b) to formulate an acceptable model for hydrate formation kinetics. The reader may wish to investigate details of this review further, via references contained in several recent monographs.
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  • 44
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    Oxford University Press
    In:  In: Tectonic Boundary Conditions for Climate Reconstructions. , ed. by Crowley, T. J. and Burke, K. C. Oxford Monographs on Geology and Geophysics, 39 . Oxford University Press, New York, pp. 116-143. ISBN 0-19-511245-8
    Publikationsdatum: 2018-02-06
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  • 45
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (3). pp. 919-932.
    Publikationsdatum: 2021-05-05
    Beschreibung: Octopuses ( Eledone cirrhosa (Octopoda: Cephalopoda)) held in an aquarium were subjected to varying conditions of feeding and starvation to evaluate putative indices of feeding and growth. Specific growth rate (%d −1 ) was linearly related to feeding rate (% of the body mass d −1 ) in animals with a mean body mass of 250 g at 15°C. Maximum growth rates varied between 〉 2% d −1 (body weights 〈 300 g) to 〈 1% d −1 (body weights ≤ 900 g) but specific growth rates were not related to body weight. Growth rates became negative (weight loss) after one week without food. The digestive gland index (DGI) was significantly correlated with short and long-term feeding and specific growth rates, and with body weight. Muscle RNA concentration was linearly correlated with growth rate during the previous 1–3 weeks but not with feeding rate. RNA:protein ratios were not different between mid-arm and mantle sample sites but arm tip values were significantly higher. RNA:protein ratio was related to body weight only in feeding animals. It is concluded that DGI is an index of feeding rate and that RNA:protein ratio can be used as an index of recent (~ 4 weeks) growth rate.
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  • 46
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (2). pp. 577-586.
    Publikationsdatum: 2021-04-23
    Beschreibung: Growth in Loliolus noctiluca (Myopsida: Loliginidae) in Western Port, Victoria, Australia was studied from statolith growth increments. Tetracycline staining experiments verified previous work on tropical forms of this species that showed growth increments to be deposited daily. A logistic growth function described the relationship between length and increment number. There appear to be major differences in the form of growth, longevity and life history pattern between tropical and temperate forms of this species. These are probably attributable to differences in environmental conditions.
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  • 47
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    Oxford University Press
    In:  ICES Journal of Marine Science, 55 (1). pp. 14-33.
    Publikationsdatum: 2021-04-21
    Beschreibung: Length-frequency data on squid (Loligo forbesi) collected during trawling surveys in Scottish waters from 1980 to 1994 were analysed to describe temporal and spatial patterns in abundance and to examine the prospects for using survey abundance to forecast fishery abundance. Loligo was patchily distributed in space and time. Distribution patterns in the North Sea in February appeared to be strongly related to bottom temperature (squid avoided waters 〈7°C) and, to a lesser extent, salinity (more squid in more saline water). For other areas and times, no temperature or salinity data were available, but there were trends for squid on the west coast to be more abundant in westerly areas and higher latitudes, and for squid at Rockall to be more abundant in shallow water. Inter-annual trends in abundance differed between the North Sea, west coast and Rockall, but average survey abundances for the North Sea and west coast tended to be positively correlated. For the North Sea and west coast, survey abundance was positively correlated with fishery abundance for the same month and area, and average abundance for the February North Sea survey was a reasonable predictor of commercial CPUE in the autumn of the same year (the peak of the fishery). Some of the observed trends were consistent with the existence of a stock-recruitment relationship but may indicate that abundance in a given calendar year is linked to climatic factors.
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  • 48
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    Cambridge University Press
    In:  Journal of Zoology, 244 (2). pp. 185-200.
    Publikationsdatum: 2021-04-29
    Beschreibung: Two large (dorsal mantle length 42.5 and 47.5 cm), mated spent females of circum‐Antarctic bathypelagic cranchiid squid Galiteuthis glacialis were caught early in March 1992 at the surface of the ice hole in the western Weddell Sea over depths 1915‐1920 m by the team of the U.S.A.‐Russian Ice Station Weddell‐I. The structure of the reproductive system of adult females is described for the first time in detail. Both were gelatinous, devoid of tentacles, with empty or almost empty stomachs. The empty spermatangia (sperm reservoirs of spermatophores) 30‐35 mm in length were distributed in the mantle tissues parallel to the mantle surface and to each other in the dorso‐anterior part of the mantle: 13 in one female, parallel to the body axis, and 20 in the other, parallel (13) or perpendicular (7) to the body axis. In the latter case, they represented probably two mating events. The spermatangia lay nearer to the inner than the outer mantle side and opened by a round window on the inner side; the skin with chromatophores above them remained intact. The spermatozoa had one flagellum and rod‐like heads, length 5.0‐5.3 μm, width 1.2‐1.5 μm. The most characteristic features are: a very simple type of blood vessel branching making each micro‐gonad currant‐like, not grape‐like; a very compact disposition of oviducal, nidamental glands and gill, forming a united complex located on both sides of the mantle cavity; and an ovary connected by mesentery along all its length with the continuation of the stomach from the caecum to the end of the gastrogenital ligament. Only immature degenerating trophoplasmatic oocytes, length 0.9‐1.4, av. 1.0‐1.2 mm, were contained in ovaries; only one mature egg (length 3.3 mm, width 2.4‐2.5 mm) was found in each female. The absence of oocytes 〈0.9 mm and 1.5‐3.2 mm indicates that the maturation of oocytes proceeds rather synchronously, one large portion of eggs (some tens of thousands) matures in a short time while others degenerate. The residual fecundity is assessed to be approximately 20,000 eggs. It is hypothesized that mating occurs shortly before spawning and that mature males do not undergo gelatinous degeneration and do not lose tentacles. Spermatophores are placed on the inner side of the female's mantle with the aid of the male's tentacles and/or arms (less probably by the penis), but the exact mode of implantation is unclear. Spawning probably occurs at depths of adult habitat (approx. 500–2500m), may be multiportional but short; the exhausted female loses neutral buoyancy, rises to the surface and dies. Rising to the surface after spawning is a common feature of females of many meso‐ and bathypelagic squids undergoing gelatinous degeneration during maturation (Onychoteuthidae, Gonatidae, Histio‐teuthidae, Cranchiidae, etc.) and may explain the common occurrence of large deep‐water squids in the stomachs of seabirds, including those incapable of diving, and marine mammals.
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  • 49
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    Oxford University Press
    In:  Journal of Molluscan Studies, 64 (1). pp. 21-34.
    Publikationsdatum: 2021-04-21
    Beschreibung: An investigation was carried out on the recently discovered ‘giant’ extra large (XL) form of the squid Sthenoteuthis oualaniensis from the Arabian Sea. The sample consisted of 2 males, which have not been previously described, and 13 females. Diet composition, parasite loading, sucker ring dentition, biolumi-nescence and sexual dimorphism were examined and compared to known parameters of the medium (M) form. Reproductive strategy, potential fecundity, egg size distribution in the ovary and oviducts were examined in mature XL females. Evidence of multiple spawning in the giant form was also investigated. Overall body shape, bioluminescent structures and coloration of the giant form were similar to the M form, though the XL form had a smaller fin angle than the M form. The mature female XL form has a dorsal mantle length about twice that of a mature female M form. Adult females of the XL form have a dorsal mantle length about twice that of adult males of the same form. Differences between males and females were found in arm sucker ring dentition and parasite load, suggesting a difference in diet. This could be linked to size differences between the sexes. A strong correlation between ovary mass and mantle length was found (r2 = 0.64). Poor correlation was found between mantle length and oviduct mass (r2 = 0.128) and potential fecundity (r2 = 0.07). Potential fecundity ranged between 2–5 million eggs and the holding capacity of the oviducts was approximately 300, 000 eggs. This combined with the presence of spermatangia and the presence of food in the stomach suggest that the XL form is a multiple spawner. S. oualaniensis appears to have a plastic phenotype and has adapted to the Arabian Sea conditions by evolving the capacity to grow to a giant size.
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  • 50
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (2). pp. 561-575.
    Publikationsdatum: 2021-04-22
    Beschreibung: A total of 57 comparative hauls using a rectangular midwater trawl with a fishing mouth area of 50 m 2 (RMT 50) were carried out along the sides of an imaginary triangle south of Madeira in 1986. A total of 1258 cephalopods were caught, giving a mean of 22 per haul with a range from 0 to 67. The nets were used with a diver's light on the top bar which was either switched off or was operated with a 20, 70 or 150 W bulb, powered by a car battery. A significantly greater number of individuals per haul was caught with lights on than without lights, increasing from a mean of 13·5–25·1, a factor of 1·8. Similarly, the number of species caught was increased from a mean of 7 to 10·4, a factor of 1·5 and the volume of cephalopods was increased from a mean of 41·1–162·3ml, a factor of 3·9. Similar comparisons made for catches during day or night separately and on the three courses separately also showed marked increases with the lights. Samples show that increase in power of the lights increased the total number of cephalopod individuals caught. In the 12 species with more than ten individuals, in 33 of the 36 comparisons (of number of individuals, species and volumes) there is an increase with the light. The most influenced species was Taonius pavo which increased in numbers by a mean factor of 3·9 times with 20W, 4·0 times with 70W and 6·1 times with 150W when compared with the numbers caught with no light.
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  • 51
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (3). pp. 1027-1030.
    Publikationsdatum: 2021-05-05
    Beschreibung: A specimen of Chaunoteuthis mollis (Cephalopoda: Onychoteuthidae), a mature mated female, from the Straits of Messina was examined. Measurements and indices were compared with those of Onychoteuthis banksii reported by previous authors. The differences found were attributed to the degeneration of the C. mollis specimen, due to sexual maturation. Two subocular (one under each eye) and two visceral photophores, similar to those of O. banksii , were present in the C. mollis specimen. The size of the posterior visceral photophore of C. mollis fit the regression line correlating posterior photophore diameter to mantle length in O. banksii. These results corroborate the hypothesis, put forward by other authors, that C. mollis represents the mature female of O. banksii.
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  • 52
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (3). pp. 903-917.
    Publikationsdatum: 2021-05-05
    Beschreibung: Three specimens of the giant squid Architeuthis were by-caught in demersal trawls to the west of Ireland, between April and June 1995. All three specimens were mature males, of mantle length 975–1084 mm. Although some intraspecific variation in fin, beak and gill were noticed, all three specimens were tentatively assigned to the species A. dux. The three specimens had food remains in their stomachs and food items identified included Micromesistius poutassou, Trachurus trachurus, Nephrops norvegicus and Eledone cirrhosa . Age estimates were made by counting putative daily growth increments in ground statoliths, and ranged from 294–122 d, giving percentage daily growth rates of 2·96–4·25% indicating a short life cycle and extremely rapid growth.
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  • 53
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    Oxford University Press
    In:  Journal of Mammalogy, 79 (3). pp. 1045-1059.
    Publikationsdatum: 2021-06-28
    Beschreibung: Stomach contents of a resident community of bottlenose dolphins (Tursiops truncatus) from the Sarasota Bay area of the westcentral coast of Florida were studied to examine potential factors leading to patterns of habitat use. Composition and size of prey were analyzed and correlated with feeding behavior of individual dolphins of known histories. Examination of stomach contents of 16 stranded dolphins revealed a diet composed exclusively of fish (15 species), most of which were associated with seagrasses in varying degrees. Observational records for 21 years showed that feeding typically occurred in shallow (2–3 m) waters and in the vicinity of seagrasses in 23% of cases. Dolphins usually fed alone or in small groups and on non-obligate schooling prey. The main species of prey were soniferous, an indication that passive listening may be important in detection of prey. The close agreement between species of fishes represented in stomach contents and habitat of prey, as indicated by observations of feeding, suggests that analysis of stomach contents is a reasonable approach for studying prey and feeding patterns of dolphins. Meadows of seagrass are one of the habitats of importance to dolphins in the Sarasota Bay area, and their protection is important for conservation of these animals.
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  • 54
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (3). pp. 1023-1026.
    Publikationsdatum: 2021-05-05
    Beschreibung: Deep-water trawling for fish species on the shelf slope off Scotland results in a by-catch of rare cephalopod species. The cirrate octopus Opisthoteuthis grimaldii is normally present below 800 m; at least one other species of cirrate and five species of incirrate octopus are found; significant extensions of range and depth are recorded. An incidental catch of the ommastrephid squid, Todarodes sagittatus , included a fully mature specimen and is indicative of its probable breeding locations. The results highlight the many taxonomic and systematic uncertainties surrounding the rarer cephalopod forms, and emphasize the utility of the fishing by-catch.
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  • 55
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (2). pp. 623-641.
    Publikationsdatum: 2021-04-23
    Beschreibung: Cephalopod prey of several cetacean species from Hawaiian waters were identified and quantified from the beaks in stomachs of stranded individuals. The different species of cetaceans all appear to target different species and sizes of cephalopods. Beaks from two sperm whales ( Physeter catodon ) included a total of 312 upper and 292 lower beaks (mandibles) of cephalopods. All of the cephalopods represented by lower beaks were oceanic squid belonging to 20 or more species in 14 families. The major constituents of the whale diet were Histioteuthis hoylei (45% by number and 10·9% by dry weight), Ommastrephes bartrami (7·6% by number, 30·6% by weight) and Architeuthis sp. (only 0·7% by number, but 26·5% by weight). In a Risso's dolphin ( Grampus griseus ) stomach, 1051 upper beaks and 1349 lower beaks were present. Eighteen or more genera of cephalopods in 15 families were present. The major constituents of the Grampus diet were Enoploteuthis spp. (36·1% by number and 30·1% by dry weight) and Abraliopsis spp. (23·6% by number, but only 4·9% by weight) and O. bartrami (1·3% and 32·1% respectively). The melon-headed whale ( Peponocephala electra ) eats fish as well as cephalopods which are represented by only six lower beaks belonging to five genera, Enoploteuthis, Teuthowenia, Abraliopsis, Abralia sp. and Bathyteuthis abyssicola . The beaked whale (unidentified) contained two lower beaks which were O. bartrami. Stenella attenuata also eats fish and the sample contained lower beaks, one of Enoploteuthis sp. and seven of an Abraliopsis sp.
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  • 56
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (2). pp. 673-676.
    Publikationsdatum: 2021-04-23
    Beschreibung: Observations on samples from Spanish trawlers between September and November of 1995 revealed the presence of mated females of Loligo gahi (Cephalopoda: Loliginidae) from 164–285 m depth, in the Western area of the Falkland Islands Conservation Zone. 93.8% of the mature females, and 31.0% of the maturing ones, were mated. Deposition of spermatophores always took place in the oral membrane between the connectives of arms IV. The relationships between sexual maturation and copulation have been analysed, and the hypothesis of mating acting as a ‘trigger’ of the final sexual maturation in Loligo gahi females is proposed and discussed.
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  • 57
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 78 (4). pp. 1259-1268.
    Publikationsdatum: 2021-04-23
    Beschreibung: This paper gives morphometric variations and dorsal mantle length–total weight (DML-TW) relationships for Illex coindetii in the eastern Central Atlantic area. Positive allometry was observed in males and negative in females of the species. The most variable body measurements between males and females were width and perimeter of the head. In the study area, divergence of morphometric measurement starts at 95 mm. The point of divergence, however, varies with latitude; fluctuating from 104 mm in the north (Morocco and Sahara) to 76 mm in the central area (Mauritania and north of Senegal) and 73 mm in the south (Gulf of Guinea). The relationships between DML and TW showed that sexual dimorphism due to differential growth between males and females starts to occur at 56 mm ML. The starting point of sexual dimorphism (56 mm) varies according to the zone; the higher the latitude, the later it occurs. Thus, sexual dimorphism occurs at 49 mm in the south (Gulf of Guinea), at 54 mm in the central area (Mauritania and north of Senegal) and at 74 mm in the north (Morocco and Sahara). Females grow larger than males, but males were heavier at any given length. As latitude decreased, a slow down in the increase in weight-at-length was observed in both sexes.
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  • 58
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    Cambridge University Press
    In:  Cambridge, 416 pp., Cambridge University Press, vol. 271, no. ALEX(01)-FR-77-01, AFTAC Contract F08606-76-C-0025, pp. 329, (ISBN: 0-08-043649-8)
    Publikationsdatum: 1997
    Schlagwort(e): FractureT ; Chaotic behaviour ; Non-linear effects ; SOC ; Seismicity ; cracks and fractures (.NE. fracturing) ; Earthquake precursor: prediction research ; Handbook of geophysics
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  • 59
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    Cambridge University Press
    In:  Cambridge, 264 pp., Cambridge University Press, vol. 42, no. 3, pp. 275-291, (ISBN: 0-444-51422-8)
    Publikationsdatum: 1997
    Schlagwort(e): physics ; philosophy
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  • 60
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    Cambridge University Press
    In:  Cambridge, 368 pp., Cambridge University Press, vol. 159, no. 22, pp. 662-664, (ISBN 0-470-87000-1 (HB), ISBN 0-470-87001-X (PB))
    Publikationsdatum: 1997
    Schlagwort(e): Textbook of geophysics ; Seismology ; Seismics (controlled source seismology) ; Gravimetry, Gravitation ; Geoelectrics ; Geomagnetics ; Earth tides ; Earth rotation
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  • 61
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    Oxford University Press
    In:  New York, Oxford University Press, vol. 4, no. 1, pp. 1-40, (ISBN: 1-4020-1348-5 hb, ISBN: 1-4020-1349-3 pb)
    Publikationsdatum: 1997
    Schlagwort(e): Textbook of geology ; Seismology ; Tectonics ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Earthquake hazard ; Earthquake risk ; Induced seismicity ; Magnitude ; Maximum likelihood
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  • 62
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    Cambridge University Press
    In:  New York, Cambridge University Press, vol. 4, no. 1, pp. 1-40, (ISBN 0-87071-024-9)
    Publikationsdatum: 1997
    Schlagwort(e): Earthquake ; Volcanology ; Earthquake precursor: prediction research ; Earthquake hazard ; Tsunami(s)
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  • 63
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    American Chemical Society
    In:  ACS Division of Fuel Chemistry Preprints, 42 (2). pp. 544-547.
    Publikationsdatum: 2018-04-11
    Beschreibung: Test specimens of methane hydrate were grown under static conditions by combining cold, pressurized CH4 gas with H2O ice grains, then warming the system to promote the reaction CH4 (g) + 6H2O (s???l) ??? CH4??6H2O. Hydrate formation evidently occurs at the nascent ice/liquid water interface, and complete reaction was achieved by warming the system above 271.5 K and up to 289 K, at 25-30 MPa, for approximately 8 hours. The resulting material is pure methane hydrate with controlled grain size and random texture. Fabrication conditions placed the H2O ice well above its melting temperature before reaction completed, yet samples and run records showed no evidence for bulk melting of the ice grains. Control experiments using Ne, a non-hydrate-forming gas, verified that under otherwise identical conditions, the pressure reduction and latent heat associated with ice melting is easily detectable in our fabrication apparatus. These results suggest that under hydrate-forming conditions, H2O ice can persist metastably at temperatures well above its melting point. Methane hydrate samples were then tested in constant-strain-rate deformation experiments at T= 140-200 K, Pc= 50-100 MPa, and ????= 10-4-10-6 s-1. Measurements in both the brittle and ductile fields showed that methane hydrate has measurably different strength than H2O ice, and work hardens to a higher degree compared to other ices as well as to most metals and ceramics at high homologous temperatures. This work hardening may be related to a changing stoichiometry under pressure during plastic deformation; x-ray analyses showed that methane hydrate undergoes a process of solid-state disproportionation or exsolution during deformation at conditions well within its conventional stability field.
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  • 64
    Publikationsdatum: 2020-07-20
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  • 65
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    Wiley
    In:  Ecological Monographs, 67 (1). pp. 65-87.
    Publikationsdatum: 2017-01-26
    Beschreibung: At a subtidal, soft-bottom site in the western Baltic Sea, mussel (Mytilus edulis) patches co-occur with high predator abundances. Sea star (Asterias rubens) biomasses, in particular, exceed reported values considered sufficient for restricting mussels to the intertidal zone. To determine how mussels can persist in the face of intense predation, we decomposed patch space occupancy into the relative contributions of newly arriving individuals (recruitment) and of increases in body size of the individuals already present in the patch over 13 mo. Sea stars, as major predators, were only able to control 77% of the potential per capita recruitment rate of 91 individuals/yr in 2 m depth. The remaining recruitment rate of 21 individuals/yr was sufficient to allow patches to occupy 1.6 times more space per year. Transplantation of patches to 6 m depth, where recruitment is negligible, revealed that sea stars were also ineffective in controlling mussel coverage through consumption of larger mussels (〉1 yr, 〉30 mm shell length). In deeper water, space occupancy of patches through increases in mussel body size was able to balance predation mortality, demonstrating that mussels attained a relative refuge in size at only 33 mm shell length. Based on the measured shell growth rates, mussels attain this size after ≈15 mo. In situ observations of Asterias feeding activity, the ratios between necessary predator sizes to attack prey of a given size, and predator size distributions suggest that sea stars were on average too small to feed effectively on adult (〉1 yr) mussels. Probably, Asterias cannot respond to abundant prey and increase its maximal body size at the site because salinities are at its lower tolerable limit (12–18 g/kg). Thus, bottom-up factors such as high prey productivity in concert with subtle size-based ineffectiveness of the predator population allow otherwise unstable predator–prey populations of a generalist predator and its preferred prey to coexist. Although mussel predators were unable to decimate mussels to local extinction, a release of experimental mussel patches from predation with strong recruitment (2 m depth) resulted in an approximately sevenfold yearly areal increase in shallow treatments, which would lead to a 100% mussel cover at the site within 1 yr. Given that mussels can dominate both rocky substratum and soft sediment, we also studied the effect of substratum quality in factorial combination with presence/absence of predation and water depth on mussel abundance. Attachment to stable substratum did not affect recruitment to the patches or patch space occupancy, but it completely prevented patch dislodgment and subsequent drift. In contrast to rocky shores, mussel patch dislodgment may represent the major mode of patch dispersal and new patch formation in soft-bottom environments as demonstrated by a drift collector fence.
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  • 66
    Publikationsdatum: 2018-05-16
    Beschreibung: There has been a widespread increase in the reporting of harmful and ‘nuisance’ algal blooms in the coastal ocean over the past few decades. On the global scale this is suspected to be a consequence of coastal eutrophication, however, on a case-by-case basis there is usually insufficient evidence to discriminate between the effects of human and natural causal factors. Intense blooms of the ‘Brown Tide’ unicellular algae (Aureococcus anophagefferens) have occurred sporadically since 1985 in coastal waters of Eastern Long Island and have devastated the local commercial scallop fishery. Analysis of an 11-year time-series dataset from this region indicates that bloom intensity is correlated with higher salinities and inversely correlated with the discharge of groundwater. Laboratory and field studies suggest that whereas salinity is unlikely to represent a direct physiological control on Brown Tide blooms, the addition of inorganic nitrogen tends to inhibit Brown Tide blooms. Budget calculations indicate that the inorganic nitrogen supply from groundwater is 1–2 orders of magnitude higher than any other external source of nitrogen for this ecosystem. Biweekly time series data collected in 1995 demonstrate that Brown Tide blooms utilize dissolved organic nitrogen (DON) for growth, as evidenced by a large decrease in DON parallel with an increase in cell abundance. On an interannual basis, bloom intensity was also positively correlated with mean DON concentrations. We hypothesize that bloom initiation is regulated by the relative supply of inorganic and organic nitrogen, determined to a large extent by temporal variability in groundwater flow. The 1980s and 1990s were characterized by exceptionally high and interannually variable groundwater discharge, associated with a large-scale climate shift over the North Atlantic. This, coupled with the time-lagged discharge of groundwater with high nitrate concentrations resulting from increased fertilizer use and population increase during the 1960s and 1970s, may have been a key factor in the initiation of Brown Tide blooms in 1985
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  • 67
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    American Chemical Society
    In:  Journal of Natural Products, 60 (9). pp. 874-879.
    Publikationsdatum: 2020-07-22
    Beschreibung: Seven new labdane diterpenoids, leopersin G−L (1−4, 6−7) and 15-epi-leopersin J (5), and two known ones, 13-hydroxyballonigrinolide (8) and ballotenol (9), were isolated from the aerial parts of Leonurus persicus along with β-sitosterol and stigmasterol. The structure determinations were mainly based on 1D and 2D NMR spectra. The stereochemical configuration of ballotenol (9) was reestablished by 2D ROESY spectroscopy and by single-crystal X-ray diffraction analysis.
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  • 68
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    Oxford University Press
    In:  Journal of Molluscan Studies, 63 . pp. 19-28.
    Publikationsdatum: 2021-04-16
    Beschreibung: The sexual cycle of the cuttlefish, Sepia officinalis, from the northern part of the Bay of Biscay was followed over several years (1988 to 1990 and 1992 to 1993). Sucessive maturity stages are reached at the same time regardless of site in the northern part of the Bay. In this area, the majority of cuttlefish reproduce during their second year of life (group II) whereas the remainder reproduce in their first year (group I). The first visible signs of sexual development concern the testis in males and the genital tract in females. Males mature earlier than females: the first spermatophores appear in July (group II) and October (group I) while mature eggs appear from December (group II) and March (group I). The breeding season lasts from about mid-March to late June (3.5 months).
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  • 69
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    Mineralogical Society | Cambridge University Press
    In:  Clay Minerals, 32 (4). pp. 587-596.
    Publikationsdatum: 2020-12-17
    Beschreibung: Changes in the molecular structure of a highly ordered kaolinite, intercalated with urea and potassium acetate, have been studied using Raman microscopy. A new Raman band, attributed to the inner surface hydroxyl groups strongly hydrogen bound to the acetate, is observed at 3605 cm (super -1) for the potassium acetate intercalate with the consequential loss of intensity in the bands at 3652, 3670, 3684 and 3693 cm (super -1) . Remarkable changes in intensity of the Raman spectral bands of the low-frequency region of the kaolinite occurred upon intercalation. In particular, the 144 and 935 cm (super -1) bands increased by an order of magnitude and were found to be polarized. These spectroscopic changes provide evidence for the inner surface hydroxyl group-acetate bond being at an angle approaching 90 degrees to the 001 face. Decreases in intensity of the bands at 243, 271 and 336 cm (super -1) were observed. The urea intercalate shows additional Raman bands at 3387, 3408 and 3500 cm-1 which are attributed to N-H vibrations after formation of the urea-kaolinite complex. Changes in the spectra of the inserting molecules were also observed.
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  • 70
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    Oxford University Press
    In:  Journal of Molluscan Studies, 63 (3). pp. 311-325.
    Publikationsdatum: 2021-04-19
    Beschreibung: Parsimony analysis of 29 finned and finless octopod taxa considered 66 anatomical and morphological characters to discover synapomorphies that unite monophyletic groups. The resultant cladogram (177 equally parsimonious trees at 191 steps, CI 0.429) resolved all relationships except those among the 16 exemplars of the Octopodidae included and those among Tremoctopus, Ocythoe and Argonauta. Bootstrap values of over 90% support the monophyly of the finned and finless octopods, relationships among the finned octopods, the bolitaenids and the monophyly of Haliphron, Tremoctopus, Ocythoe and Argonauta; bootstrap values for other nodes range from 57 to 79%. Among finned octopods, specimens representing Grimpoteuthis are basal, as Voss (1988a) suggested. Specimens of Opisthoteuthis represent a distinct lineage, and are sister taxon, in this analysis, of Cirroteuthis (although specimens of Stauroteuthis could not be included). New definitions of the genera Opisthoteuthis and Grimpoteuthis are provided to reflect their separate evolutionary histories rather than their overt morphological similarity. Among finless octopods, bolitaenids are basal. The monophyletic Octopodidae is the sister taxon to the clade containing the sister taxa Vitreledonella and Amphitretus, and Haliphron, Tremoctopus, Ocythoe and Argonauta. The Ctenoglossa and Heteroglossa, families grouped by shared radular dentition, are diphyletic and paraphyletic, respectively. The cladistic relationships demonstrate that both the Vitrele-donellidae and Idioctopodidae are junior synonyms of the Amphitretidae; despite conspicuous morphological differences separating these taxa, they share a recent evolutionary history.
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  • 71
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    Wiley
    In:  Molecular Ecology, 6 (3). pp. 297-298.
    Publikationsdatum: 2021-04-22
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  • 72
    Publikationsdatum: 2021-04-16
    Beschreibung: Allocation processes play a central role in life history theories. Yet very few studies have been carried out on the link between foraging and life history in the context of allocation of resources. Here we report a study examining the relationship between foraging and allocation of resources in the Wandering Albatross Diomedea exulans of Crozet Islands. We simultaneously studied individual foraging strategies at sea and differential allocation to reproduction and storage by measuring the energy supplied to chicks and the variation of body mass of the adult. Satellite tracking and continuous monitoring of nest attendance by adults showed that while rearing a chick Wandering Albatrosses have two specific alternative foraging strategies. They either forage in short trips, short in duration and close to the colony over the southeastern slope of the peri‐insular shelf, or in long trips far from the colony in the oceanic waters north of Crozet. On average, birds made five successive short trips before making a long trip. Chicks received a meal every 1.8 d and were fed with fresh prey, 72% squid and 24% fish, and a liquid fraction composed of oil and water. During short trips birds appear to rely to a great extent on Moroteuthis ingens, a squid species probably available in large numbers at the southeastern edge of the Crozet shelf. The measure of energy flows indicates that 74% of the energy delivered to the chick comes from short trips, whereas only 33.8% of the total energy is gained at sea during these trips. Males spent a greater proportion of their time foraging in short trips than females, and consequently chicks received 61.3% of their meals from males and 38.7% from females. Adult birds tended to lose mass after short trips and to lose more mass with increased duration of short trips, whereas they gained mass after long trips. They initiated long trips when their body mass was low. Although Wandering Albatrosses are able to provision their chicks at a rapid rate because of the proximity of an abundant resource, birds still have to forage far from the colony to restore their body condition. Estimates of energy yield explain this paradox, as they suggest that the rate at which prey is caught during short trips in shallow waters is half that during long trips in oceanic waters. The significance of the twofold foraging strategy in relation to food availability and foraging efficiency is discussed.
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  • 73
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 77 (4). pp. 1109-1137.
    Publikationsdatum: 2021-04-21
    Beschreibung: Recent attention to members of the sepiolid squid genus Euprymna and symbiotic associations with luminescent bacteria ( Vibrio fischeri strains) has prompted a review of this poorly-resolved group of squids. Twelve nominal species have been placed in this genus of which the majority are ill-defined, known only from their original descriptions and separated on the basis of inadequate characters. As a first step in resolving this group, a temperate Australian species, the Southern dumpling squid, Euprymna tasmanica , is here redescribed in detail. As the genus Euprymna currently stands, most members are only distinguished on the number and position of enlarged suckers in mature males. No diagnostic characters are available to identify females. All nominal species placed in this genus are reviewed and a key to proposed valid species is presented. Six species are considered here to be valid: Euprymna berryi, E. hoylei, E. morsei, E. scolopes, E. tasmanica and an undescribed species treated here as Euprymna sp. 1. Euprymna similis is a synonym of E. morsei of Japan. Due to inadequate original descriptions, and lost or poor type material, two species are considered here to be nomen dubia ( E. schneehageni and E. pusilla ), while the taxonomic status of four additional species remain unresolved ( E. albatrossae, E. bursa, E. phenax and E. stenodactyla ).
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  • 74
    facet.materialart.
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    Wiley
    In:  Journal of Avian Biology, 28 (3). pp. 264-267.
    Publikationsdatum: 2021-04-19
    Beschreibung: When King Penguin Aptenodytes patagonicus males arrive on the breeding grounds to start courtship, their energy reserves must sustain them during a fast lasting about five weeks, including the first incubation shift. If the female is delayed in relieving the incubating male, he must make a state-dependent decision of how long to wait until abandoning the egg (i.e. breeding failure). This is ultimately a life-history trade-off between current reproduction and future survival, and includes consideration of the size of his remaining energy reserves and his ability to replenish exhausted body reserves (foraging skills). Experienced males that abandoned the egg weighed significantly less (9.49 kg) at departure than relieved males (10.43 kg), but inexperienced males abandoned the egg at a nearly significantly higher body mass (10.27 kg) than experienced males. I conclude that experienced birds can compensate for lower body reserves by being more proficient foragers.
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  • 75
    Publikationsdatum: 2021-04-30
    Beschreibung: Observations of small schools of squids in captivity suggested that dominance relationships among males were based upon major differences in the frequency or duration of their agonistic behavior, but staged contests showed few differences. During staged contests, squids exhibited up to 21 separate behaviors. Some contests included a complex array of visual signals and side‐by‐side posturing (Lateral Display) followed by physical contact during Fin beating. There was behavioral variability and step‐wise escalation during the contests: squids performed either 1. long sequences of visual signaling followed by Chasing and Fleeing; or 2. short sequences of visual signaling followed by physical Fin beating and ending with Chasing and Fleeing. Size influenced outcome in all contests; larger males were more likely to win the contest. Size had no effect on contest duration, but contest duration was shorter when resource value was high, especially when a male established temporary ownership of a female. We speculate that when the perceived resource value is high, male squids are more likely to engage in a shorter yet riskier fighting tactic.
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  • 76
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    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 77 (2). pp. 561-564.
    Publikationsdatum: 2021-05-06
    Beschreibung: Records of unusual cephalopods, taken as by-catch in Irish and Scottish waters in the years 1985–1995, are presented. Of most interest are three specimens of giant squid (Architeuthis) that were caught in bottom trawls off the west of Ireland between April and June 1995, all were mature males of mantle length ∼1000 mm. Other records include a large mature female Histioteuthis bonnellii from the west of Ireland and three specimens of the gelatinous incirrate octopus, Haliphron atlanticus.
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  • 77
    Publikationsdatum: 2021-09-06
    Beschreibung: The filaria Litomosoides sigmodontis, which develops a patent infection in BALB/c mice, was used to determine the fate of a challenge inoculum following immunization of mice with irradiation attenuated infective larvae (3 subcutaneous inoculations at weekly intervals with 25 L3 irradiated at 60 krad, and challenge with 25 L3 two weeks after the final immunization). The adult worm burden of vaccinated mice was reduced to 50% of that of controls although the pattern of larval migration and microfilaraemia were not affected. Necropsies showed that the increased killing of the filariae of the challenge inoculum occurred at the L3 stage within the first 2 days of challenge. This result draws attention on the protective mechanisms operating very early and probably in the subcutaneous region.
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  • 78
    Publikationsdatum: 2021-04-19
    Beschreibung: Three time series of pelagic bird abundance collected in disparate portions of the California Current reveal a 90% decline in Sooty Shearwater (Puffinus griseus) abundance between 1987 and 1994. This decline is negatively correlated with a concurrent rise in sea‐surface temperatures; Sooty Shearwaters have declined while sea temperatures have risen. There is a nine‐month lag in the response by shearwaters to changing temperatures. The geographical scale of our study demonstrates that the decline of Sooty Shearwaters is not a localized phenomenon, nor can it be ascribed to a short‐term distributional shift. The Sooty Shearwater is the numerically dominant species of the California Current System (CCS) in summer (austral winter), with an estimated population in the late 1970s of 5 million individuals. If the observed warming of the waters of the California Current System is an irreversible manifestation of a changing global climate, then the impact upon Sooty Shearwater populations seems likely to be profound.
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  • 79
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    Unbekannt
    Cambridge University Press
    In:  Antarctic Science, 9 (4). pp. 373-380.
    Publikationsdatum: 2021-04-21
    Beschreibung: The statolith microstructure was studied in 142 females (mantle length, ML, ranging from 77–402 mm) and 119 males (72–328 mm ML) of Martialia hyadesi caught on the Patagonian and Falkland shelves and at the Antarctic Polar Frontal Zone between 1989–94. The statolith microstructure dark zone in this species, contains narrower and more numerous growth increments than the dark zones of other ommastrephid squids. Assuming daily production of putative growth increments within statoliths males live up to 12 months, and females live up to 13 months. It is likely that the life cycle lasts c. 1 yr, but immature squids with ages 〉330–340 d suggest that a part of M. hyadesi populations could have life span 〉1 yr. Growth in length was best described by the Gompertz function, whereas growth in weight was best described by the logistic function. M. hyadesi is characterized by slow juvenile growth (〈100 mm ML), fast growth of immature squids and a sharp decrease in growth rates during maturation. M. hyadesi mature later (at ages 〉270 d) than other temperate ommastrephids, but maturation is rather rapid (2–3 months). In the south-west Atlantic, M. hyadesi hatch throughout the year.
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  • 80
    Publikationsdatum: 2021-04-21
    Beschreibung: The microstructure, morphology and ontogenetic development of statoliths and age and growth of 405 planktonic paralarvae and 117 juveniles belonging to 10 species of gonatid squids (Cephalopoda, Oegopsida) were studied in the region of the continental slope in the western part of the Bering Sea (57°00′–61°30′N, 163°00′E–179°20′W). The statolith microstructure of all species was characterized by the presence of a large droplet-shaped nucleus and bipartite postnuclear zone divided into two by the first stress check, except for Berryteuthis magister which had only one stress check and an undivided postnuclear zone. In Gonatus spp., completion of development of the postnuclear zone coincided with full development of the central hook on the tentacular club. Daily periodicity of statolith growth increments was validated by maintaining 13 paralarvae of the four most abundant species in captivity. All species might be subdivided into two groups based on statolith microstructure, i.e. species with a central position of the nucleus within the first statolith check (Gonatopsis spp., Egonatus tinro and B.magister) and species with the nucleus shifted to the inner side of the first statolith check (Gonatus spp.). Comparative analysis of statolith morphology showed that paralarval statoliths have species-specific characters that allowed the construction of keys to identify species of gonatid paralarvae based on their statoliths. Analysis of paralarval growth using statoliths revealed that these cold-water planktonic gonatid paralarvae have fast growth rates, attaining a mantle length of 7–10 mm at 15–20 days and 20–25 mm at 35–70 days.
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  • 81
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    Unbekannt
    Wiley
    In:  Curator: The Museum Journal, 40 (1). pp. 30-55.
    Publikationsdatum: 2021-04-15
    Beschreibung: Models of the giant squid (Architeuthis spp.) are probably unique in natural history exhibition: they are representations of a giant living animal that has never been seen in a healthy state by a human being. Since its discovery in the mid‐nineteenth century, the giant squid has remained one of the world's great zoological mysteries. In the attempt to introduce this fabulous creature, museums around the world have resorted to life‐sized models. Yale teuthologist A.E. Verrill was responsible for the first such models in 1882; then Ward's Natural Science Establishment in Rochester, New York, manufactured and sold them. In this century, various museums (and one zoo) have made their own models of these ten‐armed monsters of the deep. Their disparate attempts to re‐create Architeuthis for the museum public represent one of the most intriguing case histories in the annals of museum exhibition.
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  • 82
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    Unbekannt
    Oxford University Press
    In:  Journal of Molluscan Studies, 63 (2). pp. 287-290.
    Publikationsdatum: 2021-04-21
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  • 83
    facet.materialart.
    Unbekannt
    Wiley
    In:  Curator: The Museum Journal, 40 (3). pp. 176-177.
    Publikationsdatum: 2021-02-15
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  • 84
    facet.materialart.
    Unbekannt
    Oxford University Press
    In:  Journal of Molluscan Studies, 63 (2). pp. 290-293.
    Publikationsdatum: 2021-05-03
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  • 85
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    Unbekannt
    Cambridge University Press
    In:  Using Plant Functional Types in a Global Vegetation Model | Plant Functional Types: Their Relevance to Ecosystem Properties and Global Change
    Publikationsdatum: 2022-03-21
    Materialart: info:eu-repo/semantics/bookPart
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  • 86
    Publikationsdatum: 2022-04-11
    Materialart: Book chapter , NonPeerReviewed
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  • 87
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    Unbekannt
    Cambridge University Press
    In:  Journal of the Marine Biological Association of the United Kingdom, 76 (01). p. 73.
    Publikationsdatum: 2020-07-16
    Beschreibung: The natural feeding of the two most abundant ommastrephid squid (Cephalopoda: Ommastrephidae) in Galician waters was studied and compared. A sample of 334 stomach contents of Todaropsis eblanae (34–222 mm ML) and 267 stomach contents of Illex coindetii (50–379 mm ML) caught by commercial trawlers was examined. A total of 21 (T. eblanae) and 23 (I. coindetii) different prey items, belonging to three zoological groups (Teleostei, Crustacea and Cephalopoda), were taken by these cephalopods. However, 43% of the T. eblanae diet comprised only one fish species, Micromesistius poutassou. The diet of these squid species was significantly influenced by the geographical area (both species), size (T. eblanae) and maturation (I. coindetii). Feeding rate of both species decreased with size, but the percentage of stomachs with food remains increased in maturing and mature females. Weight of prey captured was dependent on available prey sizes and, in small individuals, maximum prey weight was very close to the squid weight. Both squid species are mainly neritic nekto-benthic predators, but I. coindetii seems to have a broader and more pelagic diet.
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  • 88
    Publikationsdatum: 2017-07-07
    Beschreibung: A new species of the holopodid genus Cyathidium was found on rocks off Grande Comore in a depth of around 200 m. Based on external morphology of resting animals, the new species Cyathidium plantei sp. n is described, with emphasis on comparison to the only other extant species (C. foresti) as well as to the four extinct representatives of the genus. Concerning morphological characters, the new species is almost identical to the Cretaceous C. depressum. A cladistic analysis of the entire family, including the genus Holopus, shares a peculiar pattern of bending of the arms, which in principle is an apomorphic character of the family and in detail shows variations within the family. In addition, stratigraphic data are used for the determination of the evolutionary direction. This analysis reveals that the two recent species are closely related to each other, and to the fossil C. depressum. from which the entire family is probably derived.
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  • 89
    Publikationsdatum: 2018-04-26
    Beschreibung: A protein unique to phosphorus stress observed in Dunaliella tertiolecta Butcher was studied in the context of phosphate‐limited cell physiology and is a potential diagnostic indicator of phosphate deficiency in this alga. Cells were grown over a range of limited, steady‐state growth rates and at maximum (replete) and zero (phosphate‐starved) growth rates. The stress protein, absent in nutrient‐replete cells, was produced under all steady‐state phosphate‐limited conditions and increased in abundance with increasing limitation (decreasing growth rate). Cellular carbon: phosphorus ratios and the maximum uptake rate of phosphate (Vm) increased with increasing limitation, whereas the ratio of chlorophyll a: carbon decreased. Alkaline phosphatase activity did not respond to limitation but was measurable in starved, stationary‐phase cells. Fv/Fm, a measure of photochemical efficiency, was a nonlinear, saturating function of p, as commonly observed under N limitation. The maximum Fv/Fm of 0.64 was measured in nutrient‐replete cells growing at μmax, and a value of zero was measured in stationary‐phase starved cells. When physiological parameters were compared, the P‐stress protein abundance and Fv/Fm were the most sensitive indicators of the level of deficiency. The stress protein was not produced under N‐ or Fe‐limited conditions. It is of high molecular weight (〉200) and is associated with internal cell membranes. The stress protein has several characteristics that make it a potential diagnostic indicator: it is 1) unique to phosphorus limitation (i.e. absent under all other conditions), 2) present under limiting as well as starved conditions, 3) sensitive to the level of limitation, and 4) observable without time‐course incubation of live samples.
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  • 90
    Publikationsdatum: 2020-07-31
    Beschreibung: A mineralogical and 4OAr/39Ar study of 13 amphibole samples in the Kamila Amphibolite Belt and Kamila Shear Zone in northern Pakistan has found a correlation between the degree of greenschist facies alteration and quantity of excess 40Ar. Additionally, there is a north–south divide with amphibole samples from the northern region showing larger degrees of gree schist facies alteration, brittle deformation, and excess 40Ar incorporation compared to the predominantly plastically deformed, less altered, amphibole samples from the Kamila Shear Zone in the south. Acid leaching of two amphiboles from the Kamila Amphibolite Belt indicates that a large proportion of the excess 40Ar is correlated with later greenschist facies alteration hases, and can be easily removed by acid etching, thus revealing acceptable regional 40Ar/39Ar plateau ages.
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  • 91
    Publikationsdatum: 2017-11-07
    Beschreibung: High-resolution reflection seismic data obtained around Gran Canaria allow a detailed and consistent correlation of seismic reflectors of the northern and southern Canary Basins with the lithology drilled by DSDP Leg 47A SSE of Gran Canaria, as well as with major phases of volcanic activity on Gran Canaria as mapped onshore. Two prominent reflectors were chosen as marker horizons and correlated with the drilled lithology. the results indicate that reflector R7 above the Miocene volcaniclastic debris flows V1-V3 reflects the shield-building phase of Gran Canaria. Reflector R3 is interpreted as corresponding with the Pliocene Roque Nublo formation. The top of the massive island flank of Gran Canaria, defined by seismically chaotic facies, extends 44 to 72 km off the coast of Gran Canaria. West of Gran Canaria the flank of Tenerife onlaps the steeper and older flank of Gran Canaria, which, in turn, is onlapping the older flank of Fuerteventura to the east in a similar way. Erosional channels, which can also be traced up to 50 km from the area between Gran Canaria and Fuerteventura into the deeper northern basin, have been identified in the bathymetry. The data presented provide new detailed information for modelling the submarine and subaerial evolution of the central Canary Islands of Gran Canaria and Tenerife, i.e. the timing of their shield-building phases and later stages of major volcanic activity, as reflected by the position of prominent seismic reflectors in the seismic stratigraphy.
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  • 92
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    Unbekannt
    Cambridge University Press
    In:  Journal of The Marine Biological Association of The United Kingdom, 76 . pp. 327-344.
    Publikationsdatum: 2019-07-01
    Beschreibung: The size distribution of benthic nematodes was investigated along different gradients of food availability in various regions of the north-eastern Atlantic: I, across the continental margin and II, with increasing distance from the continental rise. An overall trend for miniaturization with increasing distance from the food source was found. Moreover, our results indicate that seasonally varying food supply or a periodically pulsed input of organic matter to the sea floor affects nematode size spectra. The hypothesis is proposed that the life cycle of deep-sea nematode species and hence the size structure of their populations are related to seasonal energy availability. This dependence might result in one year life spans of deep-sea nematodes and probably other meiofauna.
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  • 93
    facet.materialart.
    Unbekannt
    Wiley
    In:  Biotropica, 28 (3). p. 403.
    Publikationsdatum: 2020-06-22
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  • 94
    Publikationsdatum: 2020-07-27
    Beschreibung: Current methods for the replacement of skeletal tissue in general involve the use of autografts or allografts. There are considerable drawbacks in the use of either of these tissues. In an effort to provide an alternative to traditional graft materials, a degradable 3-dimensional (3-D) osteoblast cell–polymer matrix was designed as a construct for skeletal tissue regeneration. A degradable amino acid containing polymer, poly[(methylphenoxy)(ethyl glycinato) phosphazene], was synthesized and a 3-D matrix system was prepared using a salt leaching technique. This 3-D polyphosphazene polymer matrix system, 3-D-PHOS, was then seeded with osteoblast cells for the creation of a cell–polymer matrix material. The 3-D-PHOS matrix possessed an average pore diameter of 165 μm. Environmental scanning electron microscopy revealed a reconnecting porous network throughout the polymer with an even distribution of pores over the surface of the matrix. Osteoblast cells were found attached and grew on the 3-D-PHOS at a steady rate throughout the 21-day period studied in vitro, in contrast to osteoblast growth kinetics on similar, but 2-D polyphosphazene matrices, that showed a decline in cell growth after 7 days. Characterization of 3-D-PHOS osteoblast-polymer matrices by light microscopy revealed cells growing within the pores as well as on surface of the polymer as early as day 1. This novel porous 3-D-PHOS matrix may be suitable for use as a bioerodible scaffold for regeneration of skeletal tissue.
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  • 95
    facet.materialart.
    Unbekannt
    American Chemical Society
    In:  Journal of Natural Products, 59 (2). pp. 131-134.
    Publikationsdatum: 2020-07-22
    Beschreibung: Six new labdane diterpenoids, leopersin C (1), 15-epi-leopersin C (2), leopersin D (3), leopersin E (4), leopersin F (5), and 7-epi-leopersin F (6) were isolated from the aerial parts of Leonurus persicus. Their structures were elucidated by extensive use of 1D and 2D homonuclear and heteronuclear shift-correlated 1H−13C-NMR spectroscopic methods. Leopersin C (1) and 15-epi-leopersin C (2) were obtained as a C-15 epimeric mixture, and their structures were elucidated on this basis.
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  • 96
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    Unbekannt
    Cambridge University Press
    In:  Parasitology, 113 (3). pp. 303-309.
    Publikationsdatum: 2019-09-13
    Beschreibung: Density-dependent effects of Anguillicola crassus larval infections in the copepod intermediate host were examined experimentally. Three species of copepods (Cyclops vicinus, C. viridis and C. fuscus) were subjected to a range of doses of larval A. crassus within infection arenas. Prevalence, intensity and parasite dispersion (variance: mean abundance) values increase and then approach an asymptote as infection dose increases. Infection parameters differ between species of copepod. Increasing temperature has a negative effect on the establishment of the parasite population within the intermediate host. Parasite-induced host mortality increases with dose. These mechanisms have the potential to regulate populations of A. crassus larvae within the copepod population and hence the whole suprapopulation.
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  • 97
    facet.materialart.
    Unbekannt
    Wiley
    In:  Geophysical Journal International, 124 (2). pp. 631-635.
    Publikationsdatum: 2019-03-05
    Beschreibung: Seismic refraction velocity data from the acoustic basement (called layer 2A) have been compiled for different mid-ocean ridges. The data from post-1970 studies show a strong correlation between velocity and basement age. Importantly, velocities double in less than 10 Myr for all ridges, but for older crust, up to 160 Myr in age, velocities do not increase significantly.
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  • 98
    facet.materialart.
    Unbekannt
    Oxford University Press
    In:  Journal of Plankton Research, 18 (9). pp. 1675-1683.
    Publikationsdatum: 2021-01-19
    Beschreibung: Statolith microstructure was studied in two abundant planktonic cranchiids, Cranchia scabra (56 specimens, 38-127mm mantle lengh, ML) and Liocranchia reinhardti (34 specimens, 99-205mm ML) sampled in epipelagic waters of the western part of the Gulf of Guinea (tropical Atlantic). Growth increments were revealed in ground statoliths of both species. It was possible to distinguish two growth zones in statolith microstructure by their colour in reflected light of the microscope: the translucent postnuclear zone and pale white opaque zone. Assuming that growth increments in statoliths were produced daily, ages of the largest immature C. scabra and L. reinhardti were 166 and 146 days, respectively. Both cranchiids are fast-growing squids with growth rates in length resembling those of juveniles of tropical ommastrephids and Thysanoteuthis rhombus. Liocranchia reinhardti grows faster: its growth rate in ML is approximately twice that of same-aged C. scabra. The life cycle of both cranchiids consists of two phases. During their epipelagic phase, C. scabra and L. reinhardti feed and grow rapidly from paralarvae to immature young in the epipelagic waters, attaining 120-130 and 170-200 mm ML by ages of 4-5 months, respectively. Then they change their life style to a deepwater phase.
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  • 99
    facet.materialart.
    Unbekannt
    Wiley
    In:  Journal of Fish Biology, 49 (Suppl. A). pp. 330-336.
    Publikationsdatum: 2021-02-23
    Beschreibung: Two species of the family Bothidae (lefteye flounders), Mancopsetta maculata metadata and M. milfordi occur in the south‐west Atlantic but are caught rarely by commercial bottom trawlers. Little is therefore known about their general biology from this area. A total of 251 M. maculata and 276 M. milfordi were sampled during deep‐water exploratory fishing conducted in November 1994 within the Falkland Islands Interim and Outer Conservation Zones, at depths of 400‐1000 m, using standard commercial bottom trawling gear. The two species were found to have similar geographical distributions between 48.30′‐53.30'S and 55°‐62° W and were often obtained at the same stations in depths of 400‐900 m on the continental slope. Mancopsetta maculata maculata showed a uni‐modal cohort structure with a modal length at the 29‐cm total length size‐class. Males of M. m. maculata outnumbered females in a ratio of 3.5 : 1. Mancopsetta milfordi showed a tri‐modal length distribution, the main mode at the 37‐cm total length size‐class, with females outnumbering males in a ratio of 1.1 : 1. Length‐weight relationships and length‐at‐age information are presented for the two species. Diet was determined from the analysis of stomach contents and, although the major prey type for both species consisted of crustaceans, the morid fish Austrophycis marginata also formed an important part of the diet of M. milfordi. Key words: Mancopsetta maculata maculata; Mancopsetta milfordi; distribution; south‐west Atlantic; size; diet.
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  • 100
    facet.materialart.
    Unbekannt
    Wiley
    In:  Journal of Fish Biology, 49 (Suppl. A). pp. 298-310.
    Publikationsdatum: 2021-02-23
    Beschreibung: Records of demersal deep‐sea fish assemblages in waters around the Falkland Islands (Patagonian shelf area) are rare. Twenty deep‐water stations to the east and south of the Falkland Islands were sampled by commercial bottom trawl deployed in upper, middle and lower benthopelagic zones (depth range of approximately 500‐1000 m). Forty‐one species (22 families) of teleost fish were recorded, 10 species (two families) of elasmobranch and one species of agnathan. Different assemblages of fish were found to characterize each depth zone (e.g. Moridae in deeper waters, Bothidae and Rajidae in shallower waters), with diversity being greatest in the mid‐zone and biomass greatest in the upper and lower zones. Some species occurred in all zones but showed depth‐related abundance. Four species, namely the grenadiers Macrourus carinutus and Coelorhynchus fasciatus, the southern blue whiting Micromesistius australis, and the Patagonian toothfish Dissostichus eleginoides, accounted for 85% by weight of all fish caught. Quantitative sampling of selected species revealed depth‐related variations in their population structure. Length‐frequency analyses are presented for M. carinatus and D. eleginoides and show a tendency for larger individuals to inhabit deeper water. Discard rates from the commercial catch were sometimes high, particularly for the smaller species, raising concerns about the impact of a fishery on by‐catch species. The potential for deep‐sea fisheries in Falkland waters is discussed and further studies are suggested in the light of developing oil, gas and fishing industries. The presence of some invertebrate taxa is recorded.
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