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1.
Jean-Paul Montagner Phyllis Ho-Liu Hiroo Kanamori 《Geophysical Journal International》1990,103(3):757-758
Books Reviewed in this Article:
Seismic tomography and mantle circulation Eds O'Nions, R. K. & Parsons, B., Royal Society of London Special Publication , 1989, ISBN 0854 033823. 相似文献
Seismic tomography and mantle circulation Eds O'Nions, R. K. & Parsons, B., Royal Society of London Special Publication , 1989, ISBN 0854 033823. 相似文献
2.
More than a thousand interactions of primary heavy nuclei of the cosmic radiation with charge ≥10 and energy >1 GeV nucleon?1 in nuclear emulsion have been studied with emphasis on how the primary nucleus fragments. It has been determined that the cases of multiple successive fragmentations that have been observed do not occur more frequently than expected. The fragmentation ofZ>20 nuclei does depend on the target nucleus to some extent so it is important to try to separate the interactions in emulsion by theirN h (number of evaporation prongs). The fragmentation of 8 16 O at 2.1 GeV nucleon?1 measured at the Bevalac shows a similar dependence on target nucleus. By using data from these new interactions combined with published data we have simulated on a computer nuclear cascades in both emulsion and air. Results on these cascades are given for both primary silicon and primary iron nuclei. These results are used to discuss the fluctuations expected in extensive air showers produced by heavy primary nuclei. 相似文献
3.
Agostino Merico Toby Tyrrell Evelyn J. Lessard Temel Oguz Phyllis J. Stabeno Stephan I. Zeeman Terry E. Whitledge 《Deep Sea Research Part I: Oceanographic Research Papers》2004,51(12):1929
Several years of continuous physical and biological anomalies have been affecting the Bering Sea shelf ecosystem starting from 1997. Such anomalies reached their peak in a striking visual phenomenon: the first appearance in the area of bright waters caused by massive blooms of the coccolithophore Emiliania huxleyi (E. huxleyi). This study is intended to provide an insight into the mechanisms of phytoplankton succession in the south-eastern part of the shelf during such years and addresses the causes of E. huxleyi success by means of a 2-layer ecosystem model, field data and satellite-derived information. A number of potential hypotheses are delineated based on observations conducted in the area and on previous knowledge of E. huxleyi general ecology. Some of these hypotheses are then considered as causative factors and explored with the model. The unusual climatic conditions of 1997 resulted most notably in a particularly shallow mixed layer depth and high sea surface temperature (about 4 °C above climatological mean). Despite the fact that the model could not reproduce for E. huxleyi a clear non-bloom to bloom transition (pre- vs. post-1997), several tests suggest that this species was favoured by the shallow mixed layer depth in conjunction with a lack of photoinhibition. A top-down control by microzooplankton selectively grazing phytoplankton other than E. huxleyi appears to be responsible for the long persistence of the blooms. Interestingly, observations reveal that the high N:P ratio hypothesis, regarded as crucial in the formation of blooms of this species in previous studies, does not hold on the Bering Sea shelf. 相似文献
4.
Elizabeth A. Logerwell Phyllis J. Stabeno Christopher D. Wilson Anne B. Hollowed 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2849
Results from this study suggest that small-scale variability in the Alaska Coastal Current (ACC) and competition between juvenile pollock and capelin are potential mechanisms affecting the distribution and abundance of fishes in the Gulf of Alaska (GOA). Fish distributions in Barnabus Trough, off the east coast of Kodiak Island, were assessed using acoustic data collected with a calibrated echosounder during August–September 2002 and 2004. Trawl hauls were conducted to determine the species composition of the fish making up the acoustic backscatter. Oceanographic data were collected from moorings, conductivity–temperature–depth (CTD) probes, trawl-mounted microbathythermographs (MBT) and expendable bathythermographs (XBT). National Centers for Environmental Prediction (NCEP) reanalysis data were used to assess area winds, and information on regional transport was derived from current meters deployed on moorings north and south of Kodiak Island. The distribution of water-mass properties and fish during 2002 showed variability at the temporal scale of weeks. Juvenile pollock (age-1 and age-2) were initially most abundant in warm, low-salinity water on the inner shelf, whereas capelin were distributed primarily on the outer shelf in cool, high-salinity waters. During a 2-week period juvenile pollock distribution expanded with the offshore expansion of warm, low-salinity water, and capelin abundance in outer-shelf waters decreased. We hypothesize that wind-driven pulsing of the ACC resulted in increased transport of warm, low-salinity water through the study area. In 2004, warm, low-salinity water characterized the inner shelf and cool, high-salinity water was found on the outer shelf. However, the distribution of water-mass properties did not show the weekly scale variability observed in 2002. Area winds were consistently toward the southwest during 2004, such that we would not expect to see the wind-driven pulsing of ACC water that occurred in 2002. Age-1 and age-2 pollock were not observed in Barnabus Trough in 2004. Instead, the midwater acoustic backscatter was composed of capelin mixed with age-0 pollock, and these capelin were not restricted to the outer-shelf waters, but were found primarily in warm, low-salinity inner-shelf waters that had been previously occupied exclusively by age-1 and age-2 pollock. We suggest that this is consistent with inner-shelf waters being preferred foraging habitat for juvenile pollock and capelin. Further study of the mechanisms linking climate change with variability in the ACC is needed, as are studies of the potential for competition between juvenile pollock and capelin. 相似文献
5.
George L. Hunt Jr. Phyllis Stabeno Gary Walters Elizabeth Sinclair Richard D. Brodeur Jeffery M. Napp Nicholas A. Bond 《Deep Sea Research Part II: Topical Studies in Oceanography》2002,49(26)
We propose a new hypothesis, the Oscillating Control Hypothesis (OCH), which predicts that pelagic ecosystem function in the southeastern Bering Sea will alternate between primarily bottom-up control in cold regimes and primarily top-down control in warm regimes. The timing of spring primary production is determined predominately by the timing of ice retreat. Late ice retreat (late March or later) leads to an early, ice-associated bloom in cold water (e.g., 1995, 1997, 1999), whereas no ice, or early ice retreat before mid-March, leads to an open-water bloom in May or June in warm water (e.g., 1996, 1998, 2000). Zooplankton populations are not closely coupled to the spring bloom, but are sensitive to water temperature. In years when the spring bloom occurs in cold water, low temperatures limit the production of zooplankton, the survival of larval/juvenile fish, and their recruitment into the populations of species of large piscivorous fish, such as walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus) and arrowtooth flounder (Atheresthes stomias). When continued over decadal scales, this will lead to bottom-up limitation and a decreased biomass of piscivorous fish. Alternatively, in periods when the bloom occurs in warm water, zooplankton populations should grow rapidly, providing plentiful prey for larval and juvenile fish. Abundant zooplankton will support strong recruitment of fish and will lead to abundant predatory fish that control forage fish, including, in the case of pollock, their own juveniles. Piscivorous marine birds and pinnipeds may achieve higher production of young and survival in cold regimes, when there is less competition from large piscivorous fish for cold-water forage fish such as capelin (Mallotus villosus). Piscivorous seabirds and pinnipeds also may be expected to have high productivity in periods of transition from cold regimes to warm regimes, when young of large predatory species of fish are numerous enough to provide forage. The OCH predicts that the ability of large predatory fish populations to sustain fishing pressure will vary between warm and cold regimes.The OCH points to the importance of the timing of ice retreat and water temperatures during the spring bloom for the productivity of zooplankton, and the degree and direction of coupling between zooplankton and forage fish. Forage fish (e.g., juvenile pollock, capelin, Pacific herring [Clupea pallasii]) are key prey for adult pollock and other apex predators. In the southeastern Bering Sea, important changes in the biota since the mid-1970s include a marked increase in the biomass of large piscivorous fish and a concurrent decline in the biomass of forage fish, including age-1 walleye pollock, particularly over the southern portion of the shelf. Populations of northern fur seals (Callorhinus ursinus) and seabirds such as kittiwakes (Rissa spp.) at the Pribilof Islands have declined, most probably in response to a diminished prey base. The available evidence suggests that these changes are unlikely the result of a decrease in total annual new primary production, though the possibility of reduced post-bloom production during summer remains. An ecosystem approach to management of the Bering Sea and its fisheries is of great importance if all of the ecosystem components valued by society are to thrive. Cognizance of how climate regimes may alter relationships within this ecosystem will facilitate reaching that goal. 相似文献
6.
We report the size, abundance, and distribution (horizontal, vertical) of northern rock sole, Lepidopsetta polyxystra, larvae collected from ichthyoplankton surveys on the southeastern Bering Sea shelf near Unimak Island, in Unimak Pass, and in the Gulf of Alaska south of Unimak Island. The greatest abundances of larvae occurred within Unimak Pass and in the Bering Sea northeast of Unimak Island. Larvae were smaller and more abundant in 2002 than in 2003. Larval abundance and size varied with depth. Highest abundances were at depths of 10-30 m during the day, and larger fish appeared to migrate from below 20 m to 0-10 m at night. There was evidence of multiple spawning locales and larval dispersal pathways that were depth- and area-specific. Northern rock sole larvae spawned west of Unimak Pass along the Aleutian Islands may be transported northward by the Bering Slope Current. Larvae spawned in the Gulf of Alaska and advected through Unimak Pass are differentially dispersed, primarily to the middle and outer shelves along the 100 m and 200 m isobaths, or along the Alaska Peninsula. Larvae spawned along the Alaska Peninsula east of Unimak Island appear to have the greatest chance of being transported to nursery areas in the coastal domain. Dispersal of near-surface northern rock sole larvae in any of these locations is likely influenced by wind-driven advection, but below-surface (>10 m) northern rock sole larval transport is probably more affected by factors that modulate geostrophic flow rather than wind-driven surface currents. 相似文献
7.
8.
Microbial ammonia oxidation and enhanced nitrogen cycling in the Endeavour hydrothermal plume 总被引：1，自引：0，他引：1
Ammonium was injected from the subseafloor hydrothermal system at the Endeavour Segment, Juan de Fuca Ridge, into the deep-sea water column resulting in an -rich (?177 nM) neutrally buoyant hydrothermal plume. This was quickly removed by both autotrophic ammonia oxidation and assimilation. The former accounted for at least 93% of total net removal, with its maximum rate in the neutrally buoyant plume (?53 nM d−1) up to 10-fold that in background deep water. Ammonia oxidation in this plume potentially added 26-130 mg into the deep-sea water column. This oxidation process was heavily influenced by the presence of organic-rich particles, with which ammonia-oxidizing bacteria (AOB) were often associated (40-68%). AOB contributed up to 10.8% of the total microbial communities within the plume, and might constitute a novel lineage of β-proteobacterial AOB based on 16S rRNA and amoA phylogenetic analyses. Meanwhile, assimilation rates were also substantially enhanced within the neutrally buoyant plume (?26.4 nM d−1) and accounted for at least 47% of total net removal rates. The combined oxidation and assimilation rates always exceeded total net removal rates, suggesting active in situregeneration rates of at least an order of magnitude greater than the particulate nitrogen flux from the euphotic zone. Ammonia oxidation is responsible for turnover of 0.7-13 days and is probably the predominant in situ organic carbon production process (0.6-13 mg C m−2 d−1) at early stages of Endeavour neutrally buoyant plumes. 相似文献
9.
Occurrence and distribution of vibrios in fishes and shellfishes in coastal waters of Hong Kong 总被引：1，自引：0，他引：1
Xu Huaishu Li Jun Phyllis Brayton Norman Y. S. Woo David Swartz Zhang Shuting Rita R. Colwell 《海洋学报(英文版)》1998,17(4):545-553
INTRODUCTIONTheoccurrenceanddistributionofhalophilicvibriosinthecoastalwatersofHongKonghasbeenrePorted(Chanetal.,l986).Theresultsshowedthatvibrioswerepresentduringthesum-mermonthsinHongKongcoastalwatersatconcentrationsof9oto67ooind./cm3,accountingo.4l%~4o%ofthetotalbacterialPOpulationofthe48isolatesexaminedindetail.Theyob-servedV.Paraheamolyticus,V.harvha,V.vulnfficus,V.camPbelliandV.fiuvialis.Becausemanyofthevibri0species,includingsome0ftheisolatesbyChanetal.(1986)fromHongKongwate… 相似文献
10.
Gleb Panteleev Dmitri Nechaev Vladimir Luchin Phyllis Stabeno Nikolai Maximenko Motoyoshi Ikeda 《极地研究(英文版)》2008,19(2):123-134
The Bering Sea circulation is derived as a variational inverse of hydrographic profiles（ temperature and salinity） , atmospheric climatologies and historical observation of ocean curents. The important result of this study is estimate of the mean climatological sea surface height （SSH） that can be used as a reference for satellite altimetry sea level anomaly data in the Bering Sea region. Numerical experiments reveal that, when combined with satellite altimetry, the obtained reference SSH effectively constrains a realistic reconstruction of the Amukta Pass circulation. 相似文献