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  • 1
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    Seismic Earth: Array Analysis of Broadband Seismograms (2005)
    AGU
    In:  Washington, D.C., 280 pages, AGU, vol. 81A and 81B, no. 22, pp. 65-70, (ISBN 0-87590-422-X)
    Details
    Publication Date: 2005
    Keywords: Seismology ; Seismic arrays ; Data analysis / ~ processing ; Ray seismics ; Synthetic seismograms ; Modelling ; Wave propagation ; Waves ; Earth model, also for more shallow analyses ! ; Physical properties of rocks ; Broad-band
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Freshwater and brine behaviours in the Arctic Ocean deduced from historical data of ð​18O and alkalinity (1929-2002 AD) (2005)
    AGU
    In:  Journal of Geophysical Research: Oceans, 110 (C10003).
    Details
    Publication Date: 2020-07-23
    Description: The long-term data sets of total alkalinity (TA) (1929–2002 A.D.) and δ18O (1966–2002 A.D.) are used to investigate freshwater and brine distributions in the Arctic Ocean. Fractions of sea ice meltwater and other freshwaters (OF) (precipitation, river runoff, and freshwater carried by Pacific water implied as salinity deficit) are calculated on the basis of salinity-TA and salinity-δ18O relationships. Rejected brine during sea ice growth resides in surface water in the central Arctic Ocean, while net melting is found along the surface flow of water from the Pacific and Atlantic oceans. Distribution of OF at 10 m water depth suggests that Russian runoff leaves the shelf mainly west of the Mendeleyev Ridge, enters into the deep basin, and exits from the ocean through the western part of Fram Strait. The influence of Mackenzie River water is limited in the region and in depth. Accumulation of freshwater in the Canadian Basin is caused by deep penetration of OF with brine, indicating the transport of freshwater by shelf-derived water. The major origin of shelf-derived water entering into the upper halocline layer in the Canadian Basin should be the Chukchi and East Siberian Sea shelves, and the main freshwater sources are the salinity deficit of Pacific water and/or Russian runoff. An increase in OF inventory accompanied by an increase in brine content may suggest an increase of the shelf-derived water supply into the western Canadian Basin in anticyclonic years.
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  • 3
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    Freshwater control of onset and species composition of Greenland shelf spring bloom (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 288 . pp. 45-57.
    Details
    Publication Date: 2015-09-22
    Description: The relationship between physical properties of the water column and spatial patchiness of phytoplankton spring bloom development on the Greenland shelf edge and in the Irminger Sea was investigated using data collected during a spring cruise (April and May 2002). The observations confirm a strong relationship between the onset and stage of bloom development and the stratification induced by freshwater input to the surface layer in the shelf region. Interestingly, at the shelf, in the region influenced by melting of the seasonal ice-cover, the vertical distribution of chlorophyll a showed a subsurface maximum at ca. 25 m depth at several stations. Since nutrients were not exhausted at these stations, such a pattern does not conform to the general picture of a spring bloom. In contrast, in the open ocean part of the Irminger Sea pre-bloom conditions and a retarded development of the phytoplankton population were observed with low, more uniform distribution of chlorophyll a. The nitrate drawdown was estimated at between 16.5 and 270 µm m–2 (mean 108.6 ± 82.2 µm m–2) and the new primary production was estimated to be between 1.3 and 21.4 g C m–2 (8.6 ± 6.5 g C m–2), corresponding to 0.42 g C m–2 d–1. The phytoplankton community in the melting ice zone consisted of Phaeocystis sp., small flagellates (〈 4 µm) and picoplankton, while diatoms were less abundant. Phaeocystis sp. contributed up to 15 g C m–2 to the carbon biomass (70% of total carbon measured), whereas the contribution of diatoms and flagellates to carbon biomass was relatively low, with up to 1.2 g C m–2 (5.7%) and up to 2.5 g C m–2 (11.7%), respectively. On the shelf the bloom starts at the very beginning of stabilisation (elevated N2 values) which results solely from the release of meltwater. The locally restricted water stability leads to a patchy phytoplankton distribution in the Irminger Sea.
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  • 4
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    Effect of solar ultraviolet radiation on the formation of shallow, early successional biofouling communities in Hong Kong (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 290 . pp. 55-65.
    Details
    Publication Date: 2019-02-05
    Description: The effect of ambient solar ultraviolet radiation (UVR) on a shallow-water (4 cm) tropical fouling community was assessed during the succession of macrobenthic species on artificial substrates at the Wong Shek fish farm, Hong Kong. The early successional communities developing under 3 radiation treatments (PAR + UV-A + UV-B = 280 to 700 nm; PAR + UV-A = 320 to 700 nm, and PAR = 400 to 700 nm) were monitored for 14 wk. A total of 8 species of algae and 8 species of invertebrates colonised the experimental tiles. During the first 8 wk of the experiments, there were no differences among treatments in diversity, percentage of cover of species and the biomass of the colonisers. During the following 6 wk, the communities exposed to UVR had lower species richness than the communities exposed to only PAR had. The species diversity (after 79 and 98 d) of the 3 treatments varied, but the total percentage of species cover and the entire community biomass were not significantly different across the experiment. Juveniles of the polychaete Hydroides elegans and the barnacle Balanus amphitrite, juveniles of the clams Perna viridis and Modiolus comptus, and the algae Enteromorpha sp., Ectocarpus sp. and Cladophora sp. were responsible for the dissimilarity between communities developed under different UVR treatments. The algae constituted a higher percentage of the cover under the full sunlight spectrum, whereas the polychaete, the barnacle and the clams were dominant in the no-UVR treatment. Our outdoor experiment revealed that UVR inhibited the settlement and decreased post-settlement survival of H. elegans. We concluded that UVR affects the composition of early successional, shallow water biofouling communities in tropical waters as well as the settlement and mortality of single species.
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  • 5
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    Linking foraging strategies of marine calanoid copepods to patterns of nitrogen stable isotope signatures in a mesocosm study (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 286 . pp. 99-106.
    Details
    Publication Date: 2018-05-31
    Description: The foraging modes of calanoid copepods differ in that stationary suspension-feeding is more easily detected by prey with strong escape responses (ciliates) than is ‘cruising’ or ‘ambushing’ feeding. Thus, the ability of a copepod to include heterotrophic prey in its diet may be associated with its foraging mode and, further, with its nitrogen stable isotope signature (δ15N). This is because a more carnivorous diet may be expected to result in a higher δ15N. We tested this hypothesis in a mesocosm study using a density gradient (0 to 80 ind. l-1) of calanoid copepods. We expected copepod δ15N to generally increase with decreasing copepod density because of increased food availability, and predicted stronger increases for cruising than for stationary suspension-feeding species. As an assemblage, copepods had a pronounced impact on the food web: diatoms and ciliates decreased, whereas nanoflagellates increased with increasing copepod density. As expected, Centropages hamatus, a cruising species, showed the strongest isotopic increase and also highest population growth at low copepod density, suggesting that it was the most efficient species in capturing ciliates. Temora longicornis, a stationary suspension-feeder, showed a uniform isotopic increase in all mesocosms, which we believe resulted from nutritional stress arising from poor feeding on both ciliates (too fast for ingestion by T. longicornis) and nanoflagellates (too small). However, Pseudocalanus elongatus, a species equally categorised as a stationary suspension-feeder, showed increases in its δ15N similar to those for C. hamatus. While this may indicate potential switching in its foraging mode, alternative explanations cannot be ruled out, partly because qualitative and quantitative aspects of trophic enrichment in our experiment could not be clearly separated. This study shows that consumer δ15N are difficult to interpret, even if potential food sources and aspects of the species’ biology are known, and thus emphasises the necessity for further laboratory studies to help better interpret zooplankton δ15N in the field.
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  • 6
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    Effects of disturbance on the diversity of hard-bottom macrobenthic communities on the coast of Chile (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 299 . pp. 45-54.
    Details
    Publication Date: 2018-05-31
    Description: The intermediate disturbance hypothesis (IDH) predicts maximal diversity at intermediate levels of disturbance, but the validity of this hypothesis is controversially discussed. In this study, results of a field experiment, which was conducted on the northern-central Chilean coast, are presented. Fouling communities on artificial settlement substrata were studied. A total of 7 disturbance frequencies were applied to previously established communities, and a single disturbance event resulted in a removal of ~20% of the biomass. Species cover was estimated at the end of the experimental period, and it was found that diversity was strongly affected by disturbance frequency. With high disturbance frequencies the composition of the community was changed, with a decrease in the solitary ascidian Pyura chilensis (Molina 1782). The decrease of P. chilensis resulted in an increase of the colonial ascidian Diplosoma sp. A unimodal relationship between disturbance frequency and species richness was found, supporting the IDH. The results suggest that disturbance sustains diversity by reducing the abundance of the dominant species (e.g. P. chilensis), preventing competitive exclusion of the subordinate species, thus allowing subordinate species to re-emerge when competition is alleviated by disturbance. The results also suggest that these species show a trade-off between competitive and colonizing abilities, pointing to the existence of a competitive hierarchy. Therefore, the presence of competitive exclusion and disturbance-induced suppression of the dominant species remains a crucial mechanism, permitting species coexistence in the context of the IDH in the system studied.
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  • 7
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    Compressed vertebrae in Atlantic salmon (Salmo salar): Evidence for metaplastic chondrogenesis as a skeletogenic response late in ontogeny (2005)
    Inter Research
    In:  Diseases of Aquatic Organisms, 64 (3). pp. 237-246.
    Details
    Publication Date: 2016-11-14
    Description: Anterior/posterior (a/p) compression of the vertebral column, referred to as 'short tails', is a recurring event in farmed Atlantic salmon. Like other skeletal deformities, the problem usually becomes evident in a late life phase, too late for preventive measures, making it difficult to understand the aetiology of the disease. We use structural, radiological, histological, and mineral analyses to study 'short tail' adult salmon and to demonstrate that the study of adult fish can provide important insights into earlier developmental processes. 'Short tails' display a/p compressed vertebrae throughout the spine, except for the first post-cranial vertebrae. The vertebral number is unaltered, but the intervertebral space is reduced and the vertebrae are shorter. Compressed vertebrae are characterized by an unchanged central part, altered vertebral end plates (straight instead of funnel-shaped), an atypical inward bending of the vertebral edges, and structural alterations in the intervertebral tissue. The spongiosa is unaffected. The growth zones of adjacent vertebrae fuse and blend towards the intervertebral space into chondrogenic tissue. This tissue produces different types of cartilage, replacing the notochord. The correspondence in location of intervertebral cartilage and deformed vertebral end plates, and the clearly delimited, unaltered, central vertebral parts suggest that the a/p compression of vertebral bodies is a late developmental disorder that may be related to a metaplastic shift of osteogenic tissue into chondrogenic tissue in the vertebral growth zone. Given the lack of evidence for infections, metabolic disorders and/or genetic disorders, we propose that an altered mechanical load could have caused the transformation of the bone growth zones and the concomitant replacement of the intervertebral (notochord) tissue by cartilaginous tissues in the 'short tails' studied here. This hypothesis is supported by the role that notochord cells are known to play in spine development and in maintaining the structure of the intervertebral disk.
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  • 8
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    Living benthic foraminifera in sediments influenced by gas hydrates at the Cascadia convergent margin, NE Pacific (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 304 . pp. 77-89.
    Details
    Publication Date: 2018-05-31
    Description: Living (Rose Bengal stained) foraminifera in gas-hydrate-influenced sediments at the Cascadia convergent margin were investigated. Foraminiferal assemblages from the southern Hydrate Ridge and neighboring basins were compared in terms of abundances, vertical distribution, diversity, and species composition. At Hydrate Ridge, the presence of shallow gas hydrates and increased porewater sulfide concentrations was indicated by extensive bacterial mats of Beggiatoa sp. and clam beds of the bivalve mollusk Calyptogena sp., generating different biological zones. Living foraminifera were found in all biological zones, in sediment layers down to 5 cm. They showed highly variable densities within all zones. The average abundance of benthic foraminifera at Hydrate Ridge differs from neighboring basins. Average species diversities are comparable between biological zones, while the average number of species increases from bacterial mats to clam fields and surrounding sediments. Foraminifera can be characterized by 5 principal component communities which explain 97.3% of the variance of the live assemblages at the southern Hydrate Ridge and neighboring basins. At Hydrate Ridge, 2 foraminiferal zones can be distinguished: (1) an Uvigerina peregrina community which characterizes sediments covered with bacterial mats and clam fields; (2) a ?Spiroplectammina biformis community in the surrounding non-seep sediments. Foraminiferal assemblages in the neighboring Western and Eastern Basin differ from the Hydrate Ridge stations.
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  • 9
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    Maternal and paternal influences on early life history traits and processes of Baltic cod Gadus morhua (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 303 . pp. 259-267.
    Details
    Publication Date: 2018-05-31
    Description: Embryo survival, larval standard length, yolk-sac area, yolk utilization and resistance to starvation were significantly influenced by the female parent and the interaction between both parents of Baltic Sea cod Gadus morhua in a gamete factorial cross of 3 females and 5 males in all possible combinations. The proportion of variance in embryonic survivorship that was due to maternity during incubation was significant during the first 4 d, but was insignificant during the 5 to 9 d interval. During the 5 to 9 d interval, the male–female interaction was significant. Standard lengths at hatch and 5 d post hatch and specific growth rate of unfed yolk-sac larvae were strongly influenced by the female. Equivalent amounts of variation in larval resistance to starvation were explained by maternity and bi-parental interaction. Paternity alone did not explain a significant amount of variation for the traits or processes examined. The bi-parental interactions reported demonstrate a female’s choice of mate could significantly influence the early life survivorship of Baltic cod offspring.
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  • 10
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    Cold-blooded divers: temperature-dependent dive performance in wild Hawksbill Turtles Eretmochelys imbricata (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 293 . pp. 263-271.
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    Publication Date: 2018-05-30
    Description: Sea turtles are diving ectotherms that are influenced by the temperature of the ambient water, although swimming activity can temper this influence via increased body temperatures enhanced by the thermal inertia of these large animals. We successfully equipped 3 nesting hawksbill turtles Eretmochelys imbricata with time–depth recorders (TDRs) to monitor water temperature and dive depth over the duration of the re-migration interval between 2 successive nesting seasons. Data sets for up to 22 mo were obtained, showing fluctuations in water temperature over the seasons. Nocturnal dive behaviour of the turtles at their foraging grounds revealed an increase in dive duration with decreasing water temperatures in winter. A model is provided to estimate dive duration for the range of temperatures experienced by this species in the wild. The data on vertical velocity during ascent and descent phases as a parameter for activity failed to show thermal dependence. It is concluded that changes in water temperature have an effect on the behavioural ecology of Hawksbill Turtles.
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  • 11
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    Population structure and fecundity of the microcopepod Oncaea bispinosa in the Red Sea - a challenge to general concepts for the scaling of fecundity (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 302 . pp. 159-175.
    Details
    Publication Date: 2018-05-30
    Description: General concepts of reproductive traits in pelagic marine copepods have been developed largely without data from the microcopepod family Oncaeidae. For a very abundant oncaeid species in the Red Sea, Oncaea bispinosa Böttger-Schnack, reproductive parameters are provided and used for testing how the copepod family Oncaeidae may fit into these concepts. Total number and vertical distribution of eggs of this species have been calculated for populations in the northernmost Red Sea and the Gulf of Aqaba during spring, based on counts of detached egg sacs retained in fine mesh net samples. Reproduction is indicated to take place in the meso- and bathypelagic zones, with maximum abundances of eggs occurring within the deep population centres of females at 250 to 450 m depth. The epipelagic population appeared to be non-reproductive. By calculating the biomass of the eggs and the females using published data on size/weight relationships, a first estimate of the reproductive potential of O. bispinosa was obtained and compared with various other oncaeid species. The presently available data for Oncaeidae in total suggest a relationship between single egg (Ec) and female (Fc) carbon weight (Ec = 0.012 × Fc0.48) that differs from corresponding regressions reported in the literature for other marine pelagic copepods. In addition, regressions are given for minimum and maximum clutch carbon related to female carbon weight. Potential egg production rates of O. bispinosa have been calculated from the observed fractions of egg-bearing females and published data on egg developmental times, as available for larger oncaeids. These production rates appear to be lower than have been observed in experimental studies for different pelagic microcopepod taxa. Remaining uncertainties in generalizing concepts for the scaling of fecundity in pelagic marine copepods are discussed, and the need for more comparable data, especially for the numerically abundant oncaeids, is emphasized.
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  • 12
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    Linking chlorophyll-nutrient dynamics to the Redfield N:C ratio with a model of optimal phytoplankton growth (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 287 . pp. 33-43.
    Details
    Publication Date: 2018-05-31
    Description: The Redfield N:C ratio is a fundamental quantity in marine biogeochemistry because it is a key determinant of the efficiency of the biological carbon pump, yet no convincing explanations have been put forward for its remarkable constancy over much of the world ocean. Phytoplankton growth models have so far been unable to account for the different relationships between growth rate and N:C ratio under nutrient and light limitation, and have not been able to predict the Redfield N:C ratio. A relatively simple model of coupled chlorophyll and nutrient dynamics is developed from the premise that phytoplankton maximize growth by optimally allocating nutrient and energy resources among com- peting metabolic requirements for nutrient uptake, light-harvesting, and growth. The model reconciles nutrient and light limitation and appears valid under both balanced and non-balanced growth condi- tions. The Redfield N:C ratio and its constancy are explained as a result of evolutionary pressure towards maximizing light-limited growth rates in relatively carbon-rich oceanic waters.
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  • 13
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    Magnitude of excess carbon sequestration into the deep ocean and the possible role of TEP (2005)
    Inter Research
    In:  Marine Ecology Progress Series, 291 . pp. 53-64.
    Details
    Publication Date: 2018-05-30
    Description: It has been suggested that TEP (transparent exopolymer particles) may provide a vehicle for non-Redfield excess carbon export into the deep sea. Here, the hypothesis that organic carbon produced in excess of the Redfield C:N ratio is sequestered in the deep ocean is tested by a model-based mass balance approach. The model looks for a value of the C:N ratio of export production which is consistent with current knowledge of the rapid change of organic matter fluxes over depth, the remineralisation C:N ratio in the interior of the ocean, and the observed C:N ratios of sinking particles in the deep sea and at the sea floor. It is estimated that the contribution of excess carbon export into the deep ocean is equivalent to 3 to 5.6% (medians, depending on model assumptions; overall range: –16 to 21%) of the conventional Redfield biological pump (C:N = 6.6). Elevated C:N ratios of sinking particles in the deep ocean of 9 to 23, and their increase with depth, can be explained by C:N ratios of export production being only slightly larger than the vertically integrated C:N ratio of remineralisation in the interior of the ocean. The basin scale effect of this preferential nitrogen remineralisation, within the seasonal thermocline, on carbon sequestration is 1 order of magnitude lower compared with Redfield equivalent remineralisation or CaCO3 sequestration. The often observed increase in the C:N ratio of sinking particles with depth does not require that the remineralisation C:N ratio increases with depth, but can also arise under conditions of constant C:N remineralisation ratios. It is concluded that only a small fraction of carbon overconsumption in the surface ocean is sequestered into the deep ocean. The majority appears to be remineralised in the upper twilight zone.
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