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Day of hatch tidewater silversides, Menidia peninsulae, were stocked at 5 fish per liter in 3 1 of seawater at 30‰ and raised for 16 days at 20°, 25° and 30 °C. Food organisms (Brachionus sp. or Artemia nauplii) were maintained at 500, 1,000, 5,000 or 10,000 organisms per 1. The influence of food density on growth of larval M. peninsulae was temperature dependent. At 20 °C, there was no difference in final size of fish based on food densities. But at 25° and 30 °C there was an increase in final body size as food density increased. There were no significant differences in survival among food densities in tests at 20°, 25° or 30 °C. However, for any given temperature and food density, the number of survivors in a replicate affected the final size attained. Optimal culture condition for larval M. peninsulae, considering both survival and growth was determined to be 5,000 food organisms per 1 at 25 °C. 相似文献
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Estuarine sediment transport by gravity-driven movement of the nepheloid layer, Long Island Sound 总被引：1，自引：1，他引：0
L. J. Poppe K. Y. McMullen S. J. Williams J. M. Crocker E. F. Doran 《Geo-Marine Letters》2008,28(4):245-254
Interpretation of sidescan-sonar imagery provides evidence that down-slope gravity-driven movement of the nepheloid layer
constitutes an important mode of transporting sediment into the basins of north-central Long Island Sound, a major US East
Coast estuary. In the Western Basin, this transport mechanism has formed dendritic drainage systems characterized by branching
patterns of low backscatter on the seafloor that exceed 7.4 km in length and progressively widen down-slope, reaching widths
of over 0.6 km at their southern distal ends. Although much smaller, dendritic patterns of similar morphology are also present
in the northwestern part of the Central Basin. Because many contaminants display affinities for adsorption onto fine-grained
sediments, and because the Sound is affected by seasonal hypoxia, mechanisms and dispersal pathways by which inorganic and
organic sediments are remobilized and transported impact the eventual fate of the contaminants and environmental health of
the estuary. 相似文献
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Quantitative analysis of small-plastic debris on beaches in the Hawaiian Archipelago 总被引：1，自引：0，他引：1
Small-plastic beach debris from nine coastal locations throughout the Hawaiian Archipelago was analyzed. At each beach, replicate 20 l samples of sediment were collected, sieved for debris between 1 and 15 mm in size, sorted by type, counted and weighed. Small-plastic debris occurred on all of the beaches, but the greatest quantity was found at three of the most remote beaches on Midway Atoll and Moloka'i. Of the debris analyzed, 72% by weight was plastic. A total of 19100 pieces of plastic were collected from the nine beaches, 11% of which was pre-production plastic pellets. This study documents for the first time the presence of small-plastic debris on Hawaiian beaches and corroborates estimates of the abundance of plastics in the marine environment in the North Pacific. 相似文献
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Based on seismicity and focal mechanisms, a separate Okhotsk plate is identified which includes most of the Sea of Okhotsk, Kamchatka Peninsula, and the Suntar-Khayata Mountains, in the northeastern USSR. Using slip vectors from the largest earthquakes in the region, we obtain a North America-Eurasia pole of rotation near the Lena River delta and a Okhotsk-North America pole off western Chukotka. The computed poles satisfy observed thrust faulting mechanisms in the northern Cherskii Mountains which are discordant with models proposed by previous workers. It is suggested that the Arctic rift propagated through northeast Siberia to the Pacific, separating the Okhotsk plate and causing a recent (<3Ma) change in location of the North America-Eurasia pole of rotation. 相似文献
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Schrijver C.J. Title A.M. Berger T.E. Fletcher L. Hurlburt N.E. Nightingale R.W. Shine R.A. Tarbell T.D. Wolfson J. Golub L. Bookbinder J.A. DeLuca E.E. McMullen R.A. Warren H.P. Kankelborg C.C. Handy B.N. De Pontieu B. 《Solar physics》1999,187(2):261-302
The Transition Region and Coronal Explorer (TRACE) – described in the companion paper by Handy et al. (1999) – provides an unprecedented view of the solar outer atmosphere. In this overview, we discuss the initial impressions gained from, and interpretations of, the first million images taken with TRACE. We address, among other topics, the fine structure of the corona, the larger-scale thermal trends, the evolution of the corona over quiet and active regions, the high incidence of chromospheric material dynamically embedded in the coronal environment, the dynamics and structure of the conductively dominated transition region between chromosphere and corona, loop oscillations and flows, and sunspot coronal loops. With TRACE we observe a corona that is extremely dynamic and full of flows and wave phenomena, in which loops evolve rapidly in temperature, with associated changes in density. This dynamic nature points to a high degree of spatio-temporal variability even under conditions that traditionally have been referred to as quiescent. This variability requires that coronal heating can turn on and off on a time scale of minutes or less along field-line bundles with cross sections at or below the instrumental resolution of 700 km. Loops seen at 171 Å (～1 MK) appear to meander through the coronal volume, but it is unclear whether this is caused by the evolution of the field or by the weaving of the heating through the coronal volume, shifting around for periods of up to a few tens of minutes and lighting up subsequent field lines. We discuss evidence that the heating occurs predominantly within the first 10 to 20 Mm from the loop footpoints. This causes the inner parts of active-region coronae to have a higher average temperature than the outer domains. 相似文献
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The transition region and coronal explorer 总被引：5，自引：0，他引：5
Handy B.N. Acton L.W. Kankelborg C.C. Wolfson C.J. Akin D.J. Bruner M.E. Caravalho R. Catura R.C. Chevalier R. Duncan D.W. Edwards C.G. Feinstein C.N. Freeland S.L. Friedlaender F.M. Hoffmann C.H. Hurlburt N.E. Jurcevich B.K. Katz N.L. Kelly G.A. Lemen J.R. Levay M. Lindgren R.W. Mathur D.P. Meyer S.B. Morrison S.J. Morrison M.D. Nightingale R.W. Pope T.P. Rehse R.A. Schrijver C.J. Shine R.A. Shing L. Strong K.T. Tarbell T.D. Title A.M. Torgerson D.D. Golub L. Bookbinder J.A. Caldwell D. Cheimets P.N. Davis W.N. Deluca E.E. McMullen R.A. Warren H.P. Amato D. Fisher R. Maldonado H. Parkinson C. 《Solar physics》1999,187(2):229-260
The Transition Region and Coronal Explorer (TRACE) satellite, launched 2 April 1998, is a NASA Small Explorer (SMEX) that
images the solar photosphere, transition region and corona with unprecedented spatial resolution and temporal continuity.
To provide continuous coverage of solar phenomena, TRACE is located in a sun-synchronous polar orbit. The ∼700 Mbytes of data
which are collected daily are made available for unrestricted use within a few days of observation. The instrument features
a 30-cm Cassegrain telescope with a field of view of 8.5×.5 arc min and a spatial resolution of 1 arc sec (0.5 arc sec pixels).
TRACE contains multilayer optics and a lumogen-coated CCD detector to record three EUV wavelengths and several UV wavelengths.
It observes plasmas at selected temperatures from 6000 K to 10 MK with a typical temporal resolution of less than 1 min. 相似文献
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