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11.
Spatial intertidal distribution of bivalves and polychaetes in relation to environmental conditions in the Natori River estuary,Japan 总被引：1，自引：0，他引：1
Takeshi Tomiyama Nobuhiro KomizunaiTatsuya Shirase Kinuko ItoMichio Omori 《Estuarine, Coastal and Shelf Science》2008
This paper aims to reveal spatial variation in the abundance of infaunal bivalves and polychaetes at different spatial scales (station: 200–800 m intervals; plot: 5–20 m), and to reveal environmental variables affecting the spatial distribution of animals in the Natori River estuary, Japan. We found six bivalve species and eight polychaete species from 52 plots at 12 stations. Nuttallia olivacea and Heteromastus sp. were found to be the most abundant species of bivalves and polychaetes, respectively. Assemblage patterns of bivalves and polychaetes were classified into five distinct groups. Substrata (silt-clay contents), salinity, and relative elevation were the variables found to affect the infaunal assemblage patterns. Chlorophyll a was not a significant variable, but benthic animals were absent at sites with extremely low chlorophyll a conditions. Macrobenthic assemblage patterns were different not only between stations but often differed between plots at the same station, reflecting the complex assemblage structure of benthic invertebrates. Detailing such animal–environment relationship is essential in understanding the potential food supply for estuarine fishes. 相似文献
12.
Chan Hong Park Jeong Woo Kim Nobuhiro Isezaki Daniel R. Roman Ralph R. B. von Frese 《Marine Geophysical Researches》2006,27(4):253-266
To facilitate geological analyses of the Ulleung Basin in the East Sea (Japan Sea) between Korea and Japan, shipborne and satellite altimetry-derived gravity data are combined to derive a regionally coherent anomaly field. The 2-min gridded satellite altimetry-based gravity predicted by Sandwell and Smith [Sandwell DT, Smith WHF (1997) J Geophys Res 102(B5):10,039–10,054] are used for making cross-over adjustments that reduce the errors between track segments and at the cross-over points of shipborne gravity profiles. Relative to the regionally more homogeneous satellite gravity anomalies, the longer wavelength components of the shipborne anomalies are significantly improved with minimal distortion of their shorter wavelength components. The resulting free-air gravity anomaly map yields a more coherent integration of short and long wavelength anomalies compared to that obtained from either the shipborne or satellite data sets separately. The derived free-air anomalies range over about 140 mGals or more in amplitude and regionally correspond with bathymetric undulations in the Ulleung Basin. The gravity lows and highs along the basin’s margin indicate the transition from continental to oceanic crust. However, in the northeastern and central Ulleung Basin, the negative regional correlation between the central gravity high and bathymetric low suggests the presence of shallow denser mantle beneath thinned oceanic crust. A series of gravity highs mark seamounts or volcanic terranes from the Korean Plateau to Oki Island. Gravity modeling suggests underplating by mafic igneous rocks of the northwestern margin of the Ulleung Basin and the transition between continental and oceanic crust. The crust of the central Ulleung Basin is about a 14–15 km thick with a 4–5 km thick sediment cover. It may also include a relatively weakly developed buried fossil spreading ridge with approximately 2 km of relief. 相似文献
13.
Using all available geomagnetic data, including those obtained in a detailed survey conducted by the authors in 1970, the geomagnetic anomaly pattern if the Japan Sea has been studied. It has been established that sublinear magnetic anomalies run subparallel to the general trend of the Japanese Islands. The peak to peak amplitudes of most of these anomalies are less than 300y, their wavelengths 20 to 40 km. The anomalies are much less distinct in linearity than those found in the northwestern corner of the Pacific basin off northeastern Honshu. The linear trend is better developed in the deeper basin areas and less recognizable in the Yamato- and Kitayamato-areas. The anomaly pattern appears to support the view that the Japan Sea floor evolved through a spreading process from numerous spreading centers. A definite conclusion about the genesis of the Japan Sea, however, must await further investigation. 相似文献
14.
To understand the transport process of lithogenic particles in the ocean, we measured the grain size distributions of lithogenic
particles and measured the opal, La, Yb, Th, and Sc concentrations of the settling particles collected from time-series sediment
traps at Sta. KNOT (44°N, 155°E, water depth 5320 m) from June 2002 to May 2004. The annual mean lithogenic particle flux
observed at the lower sediment trap (5100 m) was twice as high as that at the upper sediment trap (770 m). The contribution
of Asian loess estimated by the La/Yb and the Th/Sc ratios in the lower layer was greater than that in the upper layer. The
fluxes of small lithogenic particles with sizes of 3–4 μm at the lower layer (5 to 65 mg/m2/day) were approximately four times larger than that at the upper layer (0.6 to 27 mg/m2/day). These results indicate that the horizontal addition of small particle sizes of Asian loess is a main factor in the
increase of lithogenic particles at the lower layer. The temporal variations in the small lithogenic particle flux at the
lower layer had a positive correlation with those at the upper layer (r = 0.71). The small lithogenic particle fluxes showed
a strong positive correlation with the opal fluxes (r = 0.9). We therefore conclude that the small lithogenic particles were
laterally transported and scavenged by the formation of aggregates with opal. 相似文献
15.
Hirata Takashi Zaima Nobuhiro Yamashita Kyoko Noguchi Ryoko XUE Changhu Sugawara Tatsuya 《中国海洋大学学报(英文版)》2005,4(3):193-197
In this report, we reviewed recent literature on physiologically active substances from sea cucumbers （SCs） and their activities together with results obtained from our study. Preventive properties against lipid metabolism were reported in rats using a whole SC preparation with no particular constituent specified. Administration of the preparation lowered serum and hepatic cholesterol levels and improved the HDL/LDL ratio. These functions may be attributed to the stimulatory effect of the extract on the secretion of cholesterol in feces. Novel fucosylated chondroitin sulfates （FCSs） from Ludwigothurea grisea significantly induced fibroblast growth factor 2-dependent angiogenesis in human umbilical vein endothelial cells （HUVECs）. The proangiogenetic activity seemed attributable to the action of the sulfated fucose branches on the polysaccharide. SCs contain mycosporine-like amino acids （MAAs） that are capable of absorbing UV. A biogenetic precursor of MAAs was first reported in SCs. The anti-proliferative effects of a branched chain fatty acid from a sea cucumber on prostate cancer cells was reported with the activity of 5-lipoxygenase. Glycosphingolipid constituents in SCs have been systematically analyzed over the past ten years. The results showed that the gangliosides in several SCs differed from those of mammals in that a sialic acid of SC gangliosides directly binded to glucose of cerebroside. Neuritogenic activity of the glycosphingolipids was demonstrated in vitro experiments and may lead to the development of therapeutic products for neurological disorders. Our study also showed that sphingoid bases, the hydrolyzed products of glycosphingolipids from SCs, induced significant apoptosis in several tumor cell lines. 相似文献
16.
Akihiko Murakami Tokio Matsuda Nobuhiro Watanabe Shinichi Nagasawa 《Journal of Oceanography》1976,32(5):242-248
The ability to degraden-paraffin mixture of two bacterial strains,Caulobacter sp. andFlavobacterium sp., isolated from sea water of Tokyo Bay was studied experimentally in the enriched seawater (ESW) medium. These bacteria degraded actively the mixture ofn-tridecane,n-tetradecane,n-pentadecane andn-hexadecane. The maximum rate of degradation was observed after a lag period of 2 to 8 day and these bacteria were found to degrade then-paraffin mixture at rates calculated to be in a range from 3.3×10?12 to 3.4×10?11 mg-oil cell?1 h?1 at 20°C. The maximum degradation rate,r m mg-oil l?1 h?1, was correlated with the amount of the initial totaln-paraffin,S mg-oil l?1, as expressed by the following equation: $$rm = (rm)\max \left( {\frac{S}{{S + Km}}} \right)$$ where (r m )max denotes the largest value ofr m whenn-paraffin exists in large excess andK m is a constant and represents the amount ofn-paraffin at which the degradation rate,r m , reaches 1/2 of its largest value, (r m )max. The values of (r m )max andK m were calculated to be as follows: In the case ofCaulobacter sp. (strain KM-1), (r m )max=6.0 mg-oil l?1 h?1 andK m =191 mg-oillesw ?1; in the case ofFlavobacterium sp., (r m )max=5.47 mg-oil l?1 h?1 andK m =152 mg-oillesw ?1. 相似文献
17.
Nobuhiro Isezaki 《Marine Geophysical Researches》1975,2(3):265-277
The magnetic anomaly profiles across the Japan and the Yamato Basins are analyzed to find possible spreading centers. Magnetic anomalies are first transformed and then the correlation coefficient of symmetry of the pattern of profile is computed along each profile. If the coefficient of symmetry has a notable maximum at a point and such a point lines up for different profiles, the line of these points of maximum symmetry may be a spreading center. Three possible spreading centers are obtained. Two are situated at about the axis of the Japan and the Yamato Basins, and the other is at the topographic extension of the Yamato Ridge. The age of the opening has not been identified on the magnetic time scale yet, but the strike of the proposed spreading centers suggests a pre-Eocene time. 相似文献