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441.
Malcolm Luxton 《新西兰海洋与淡水研究杂志》2013,47(3):497-504
Tangaroellus porosus, gen. nov., sp. nov., is described from three coastal localities in New Zealand. Its affinities with the family Rhodacaridae are discussed. 相似文献
442.
Malcolm E. Forster 《新西兰海洋与淡水研究杂志》2013,47(1):85-90
Patterns of ventilation, oxygen consumption (VO2), blood gas tensions (PaO2 and PaCO2) and pH were determined in shortfin eels (Anguilla australis schmidtii (Phillips)). At rest, shortfin eels (average weight 646.5 ± 64.5 g) had a VO2 of 20.4 ± 1.2 ml. kg‐1.h‐1 (n = 13) at 17.5 ± 0.2°c, with smaller fish having the highest metabolic rates. The frequency of ventilation was inversely proportional to body weight in both A. australis schmidtii and A. dieffenbachii. In air‐saturated water 10 eels exhibited periodic apnoea (mean duration 3.59 min); periods of ventilation were more variable in duration (mean 4.92 min). After 2.62 min of apnoea, the PaO2 of dorsal aortic blood had fallen from 9.12 to 1.91 kPa. Thus, although the blood has a high affinity for oxygen and the haemoglobins are 30% oxygen‐saturated at this low PaO2, the eel allows its blood to be significantly depleted in oxygen during apnoeic pauses at rest. When ventilating its gills at rest, PaO2 does not approach the PO2 of the inspired water. It is suggested that these features of respiration in eels result in a saving of metabolic costs involved in ventilation. The results are discussed in terms of the eel's ability to withstand hypoxic conditions. 相似文献
443.
Tsuyoshi Iizuka Malcolm T. McCulloch Tsuyoshi Komiya Takazo Shibuya Kenji Ohta Haruka Ozawa Emiko Sugimura Kenneth D. Collerson 《Contributions to Mineralogy and Petrology》2010,160(6):803-823
Mt. Narryer and Jack Hills meta-sedimentary rocks in the Narryer Gneiss Complex of the Yilgarn Craton, Western Australia are
of particular importance because they yield Hadean detrital zircons. To better understand the tectonothermal history and provenance
of these ancient sediments, we have integrated backscattered scanning electron images, in situ U–Pb isotopic and geochemical
data for monazites from the meta-sediments. The data indicate multiple periods of metamorphic monazite growth in the Mt. Narryer
meta-sediments during tectonothermal events, including metamorphism at ~3.3–3.2 and 2.7–2.6 Ga. These results set a new minimum
age of 3.2 Ga for deposition of the Mt. Narryer sediments, previously constrained between 3.28 and ~2.7 Ga. Despite the significant
metamorphic monazite growth, a relatively high proportion of detrital monazite survives in a Fe- and Mn-rich sample. This
is likely because the high Fe and Mn bulk composition resulted in the efficient shielding of early formed monazite by garnet.
In the Jack Hills meta-sediments, metamorphic monazite growth was minor, suggesting the absence of high-grade metamorphism
in the sequence. The detrital monazites provide evidence for the derivation of Mt. Narryer sediments from ca. 3.6 and 3.3 Ga
granites, likely corresponding to Meeberrie and Dugel granitic gneisses in the Narryer Gneiss Complex. No monazites older
than 3.65 Ga have been identified, implying either that the source rocks of >3.65 Ga detrital zircons in the sediments contained
little monazite, or that >3.65 Ga detrital minerals had experienced significant metamorphic events or prolonged sedimentary
recycling, resulting in the complete dissolution or recrystallization of monazite. 相似文献
444.
Wind Modulation of Dissolved Oxygen in Chesapeake Bay 总被引:1,自引:0,他引:1
Malcolm E. Scully 《Estuaries and Coasts》2010,33(5):1164-1175
A numerical circulation model with a simplified dissolved oxygen module is used to examine the importance of wind-driven ventilation
of hypoxic waters in Chesapeake Bay. The model demonstrates that the interaction between wind-driven lateral circulation and
enhanced vertical mixing over shoal regions is the dominant mechanism for providing oxygen to hypoxic sub-pycnocline waters.
The effectiveness of this mechanism is strongly influenced by the direction of the wind forcing. Winds from the south are
most effective at supplying oxygen to hypoxic regions, and winds from the west are shown to be least effective. Simple numerical
simulations demonstrate that the volume of hypoxia in the bay is nearly 2.5 times bigger when the mean wind is from the southwest
as compared to the southeast. These results provide support for a recent analysis that suggests much of the long-term variability
of hypoxia in Chesapeake Bay can be explained by variations in the summertime wind direction. 相似文献