共查询到20条相似文献，搜索用时 31 毫秒
1.
Long-Term Variations of Potential Temperature and Dissolved Oxygen of the Japan Sea Proper Water 总被引：4，自引：0，他引：4
Observed potential temperatures and concentrations of dissolved oxygen are analyzed to elucidate their variations during the
period from 1958 to 1996 at Stn. P (37°43′ N, 134°43′ E) and from 1965 to 1996 at Stn. H (40°30′ N, 137°40′ E) in the Japan
Sea. At Stn. P, increases of the potential temperature for the period are found below 800 m depth with the largest value of
0.16 ± 0.09°C per century at 800 m depth. At Stn. H, the potential temperature increased below 500 m depth. The increase rate
has the largest value of 0.50 ± 0.18°C per century at 500 m depth and it is 0.30 ± 0.09°C per century at 800 m depth. The
concentrations of dissolved oxygen increased around 800 m depth at Stn. P. At Stn. H, they increased above 800 m depth. On
the other hand, they decreased below 1200 m depth at both stations. The layer of the dissolved oxygen minimum has deepened
in these decades. These features appearing in the distributions of temperature and dissolved oxygen are successively simulated
by a vertical one-dimensional advection-diffusion model including consumption of dissolved oxygen and termination of the deep
water supply. These results suggest that the supply of the Japan Sea Proper Water into the deep layer, which is cold and rich
in dissolved oxygen, has been decreasing for the last four decades.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Distributions and taxonomy of phyllosoma larvae were examined in Taiwanese waters, based on ichthyoplankton samples collected
from May 1990 to July 1995. Phyllosoma larvae belonged to the two families Scyllaridae and Palinuridae representing 6 genera
and 13 species. Of the collected phyllosoma larvae, those of Scyllarus and Panulirus species were most abundant, forming 90% of total numbers. Early stage Scyllarus and Panulirus phyllosoma larvae were abundant in Taiwanese waters. Middle to late stages (except the final stage) of Panulirus phyllosoma larvae were absent from the waters throughout the year, while those of Scyllarus phyllosoma larvae were collected in the waters. This suggests that all stages of Scyllarus phyllosoma larvae may be retained in the northern part of the waters around northern Taiwan while middle to late stages of
Panulirus phyllosoma larvae may be flushed out from the waters, the sub-final and final stages then possibly returning to the waters.
An anticlockwise eddy existed in the waters off northeastern Taiwan, which may be closely related to flushing out and returning
of Panulirus phyllosoma larvae through a much longer planktonic period.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
Phyllosoma larvae collected to date in Japanese and Taiwanese waters have been classified into two genera (Linuparus, Panulirus) of the Palinuridae, four genera (Ibacus, Parribacus, Scyllarides, Scyllarus) of the Scyllaridae, and one genus (Palinurellus) of the Synaxidae. However, phyllosoma larvae of three Scyllarus species (S. bicuspidatus, S. cultrifer, S. kitanoviriosus) are absolutely dominant among the larvae collected in the waters. Scyllarus larvae are abundant in coastal waters while those of Panulirus are often collected in offshore/oceanic waters. Based on previous and ongoing studies dealing with spatial distributions
of phyllosoma larvae in Japanese and Taiwanese waters, it appears that phyllosoma and nisto larvae of the Scyllarus are retained within coastal waters north of the Kuroshio Current. On the other hand, the life history of the Panulirus (particularly P. japonicus) may be completed within the Kuroshio Subgyre: their phyllosoma larvae may be flushed out from coastal waters into the Kuroshio,
then transported through the Counter Current south of the Kuroshio into the water east of Ryukyu Archipelago and Taiwan where
they attain the subfinal/final phyllosoma or puerulus stages, once again entering the Kuroshio and dispersing into coastal
waters.
This revised version was published online in July 2006 with corrections to the Cover Date.
An erratum to this article is available at . 相似文献
4.
Phyllosoma larvae were identified and their distribution was examined, based on the larvae in ichthyoplankton samples collected in the Japanese Eel Expedition to the spawning area of A. japonica in the western North Pacific from August 30 to September 13, 1986 (Leg. 1), and from September 22 to 25, 1986 (Leg. 2), on board the R/V Hakuho-maru. Phyllosoma larvae belonged to 3 families (Scyllaridae, Palinuridae and Synaxidae) representing 6 genera and 14 species. A total of 336 palinurid and synaxid phyllosoma larvae were collected, of which 233 larvae (about 70%) were identical with P. longipes s. l, while a total of 362 scyllarid phyllosoma larvae were collected, of which 274 larvae (about 76%) were identical with S. cultrifer. Phyllosoma larvae of P. longipes s. l and S. cultrifer showed a similar distribution to each other. The larvae were abundant in the water close to Mariana Islands, although late stage examples were abundant in waters of Luzon and eastern Taiwan. Distributions of these larvae may be related intimately with the North Equatorial Current existing along 15°N. The North Equatorial Current approaches the eastern coast of the Philippines and then separates into two branches of northward and southward flows. The northward flow contributes to generating the Kuroshio Current while the southward flow goes to generate the Mindanao Current. Judging from distributions of phyllosoma larvae in the present study, it is assumed that the larvae of the above two species may have been released in Mariana Islands and transported westward from there through the North Equatorial Current. These larvae may then be transported to eastern Taiwanese waters. 相似文献
5.
Using ichthyoplankton samples collected in the Kuroshio Subgyre during early summer cruises, we examined spatial distributions
of scyllarid phyllosoma larvae in the Subgyre, particularly of the genus Scyllarus. The present study has two objectives: (1) to reveal species composition of Scyllarus phyllosoma larvae in the Kuroshio Subgyre, and (2) to examine larval recruitment of Scyllarus species as contrasted with that of Panulirus, particularly P. japonicus, the larval recruitment of which has been examined in detail. A total of 218 phyllosoma larvae collected in the present study
belonged to two families (Palinuridae and Scyllaridae) representing 5 genera and 11 species. Phyllosoma larvae of two Scyllarus species (S. cultrifer and Scyllarus sp. c) were abundant among the collected larvae, and were found mainly in the following three regions located within the
Kuroshio-Counter Current region south of Kuroshio Current: the water east of Okinawa Is., the water far east of Okinawa Is.
(or far south of Shikoku Is.), and the water around Hachijojima Is. Larvae of each of the above two Scyllarus species collected in the three regions may belong to different populations: larvae collected in the water around Hachijojima
Is. may come from their benthic populations along the Pacific coast of Honshu and Shikoku Is., central Japan, while larvae
collected in the other two regions may come from their benthic populations of the Ryukyu Archipelago and Taiwan. Judging from
their shorter larval period and current systems within the Kuroshio Subgyre, these Scyllarus larvae may be destined for death.
An erratum to this article is available at . 相似文献
6.
The objective of the paper is to use the data collected along two meridional sections (45° E and 57°30′ E) during the austral
summer (January–March) 2004 to understand the influence of seabed topography across the Madagascar and Southwest Indian Ridges
on hydrographic parameters. The study was supplemented by World Ocean Circulation Experiment (WOCE) Conductivity-Temperature-Depth
data collected during February–March 1996 along 30° E, as well as Levitus climatology. A southward shift of 2° latitude (between
45° E and 57°30′ E) was recorded for the two predominant frontal structures, i.e., the Agulhas Return Front and Southern Subtropical
Front, which is attributed to the influence of seabed topography on hydrographic parameters. No significant spatial variation
of these fronts was noted between the 30° E and 45° E meridional sections. Between latitudes 31° S and 42° S, the temperature
and salinity structures show deepening over the ridges. The Antarctic Circumpolar Current core was detected between 40°15′ S
and 43° S. 相似文献
7.
We have measured helium isotopic ratios of thirty-seven Pacific water samples from various depths collected in adjacent regions
of Honshu, Japan. The 3He/4He ratios vary significantly from 0.989 R
atm to 1.208 R
atm where R
atm is the atmospheric ratio of 1.39 × 10−6. The mid-depth (750–1500 m) profile of 3He/4He ratios at ST-1 located Northwestern Pacific Ocean east of Japan (Off Joban; 37°00′ N, 142°40′ E) is significantly different
from that at ST-2 of the Northern Philippine Sea south of Japan (Nankai Trough; 33°07′ N, 139°59′ E), suggesting that these
waters were separated by a topographic barrier, the Izu-Ogasawara Ridge. Taking 3He/4He data of the Geosecs expeditions in the western North Pacific, an extensive plume of 15% excess 3He relative to the air may be traced at ST-1 over 12,000 kilometers to the northwest of the East Pacific Rise where the mantle
helium may originate. The 20% excess found at ST-2 may be attributable to the additional source of the subduction-type mantle
helium in the Okinawa Trough. A 15% excess of 3He has also been discovered at a depth of about 1000∼1500 m at ST-3 adjacent to Miyakejima Island (33°57′ N, 139°22′ E) and
ST-4 of Sagami Bay (35°00′ N, 139°22′ E). It is confirmed that mid-depth all over the western North Pacific water is affected
by the mantle helium with a high 3He/4He ratio.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
A one-dimensional, steady-state model has been developed to understand the factors controlling vertical distributions of nutrients
such as nitrate and phosphate in the western North Pacific water columns. The model includes simple physics and some biogeochemical
processes. Nutrients are supplied by upwelling of nutrient-rich deep waters with a constant upwelling velocity and nutrient
regeneration due to decomposition of sinking particulate matter; the latter is expressed by an exponential-type export flux.
Nutrients are consumed in the water column due to uptake by marine organisms, represented by a first-order substrate kinetics.
The consumption rate constant is given as an exponential function of depth. The model has been applied to a data set of WOCE
(World Ocean Circulation Experiment) P9 one-time measurements observed in the western North Pacific. The calculated curves
fit well to observed vertical nutrient profiles from 100 m depth to over 2,500 m depth at 35 stations from 19°N to 33°30′
N along 137°E with correlation factors of greater than 0.998. A modified model, including a correction term representing a
depth-dependent upwelling velocity, can reproduce observed vertical nutrient profiles at 32 stations from 5°N to 18°30′ N
along 137°E with correlation factors greater than 0.993. The results support the hypothesis that most of the vertical nutrient
profiles in the western North Pacific are controlled by particle export flux, consumption rate, remineralization rate and
upwelling velocity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
针飞鱼属Oxyporhamphus Gill(1863)是飞鱼中形态最原始的种类.其地理分布集中于太平洋、印度洋和大西洋的热带海域.针飞鱼是大洋性小型上层鱼类,也是大洋鱼类区系营养相互关系中的重要环节;它们既可为人类食用,亦是大洋重要经济鱼类(如金枪鱼、旗鱼、枪鱼、鲯鳅等)的天然食饵,故能利用飞鱼类“集群”的习性和明显起飞的特征刘断大洋经济负类的踪迹.因此,对飞鱼类的研究,具有特别重要的意义. 相似文献
10.
Spatial Variability of Living Coccolithophore Distribution in the Western Subarctic Pacific and Western Bering Sea 总被引：1，自引：0，他引：1
Hiroshi Hattori Makoto Koike Kenichi Tachikawa Hiroaki Saito Kazuya Nagasawa 《Journal of Oceanography》2004,60(2):505-515
Vertical distributions of coccolithophores were observed in the depth range 0–50 m in the western subarctic Pacific and western
Bering Sea in summer, 1997. Thirty-five species of coccolithophores were collected. Overall, Emiliania huxleyi var. huxleyi was the most abundant taxon, accounting for 82.8% of all coccolithophores, although it was less abundant in the western Bering
Sea. Maximum abundance of this species was found in an area south of 41°N and east of 175°E (Transition Zone) reaching >10,000
cells L−1 in the water column. In addition to this species, Coccolithus pelagicus f. pelagicus, which accounted for 4.2% of the assemblage, was representative of the coccolithophore standing crop in the western part
of the subarctic Pacific. Coccolithus pelagicus f. hyalinus was relatively abundant in the Bering Sea, accounting for 2.6% of the assemblage. Coccolithophore standing crops in the top
50 m were high south of 41°N (>241 × 106 cells m−2) and east of 170°E (542 × 106 cells m−2) where temperatures were higher than 12°C and salinities were greater than 34.2. The lowest standing crop was observed in
the Bering Sea and Oyashio areas where temperatures were lower than 6–10°C and salinities were less than 33.0. From the coccolithophore
volumes, the calcite stocks in the Transition, Subarctic, and the Bering Sea regions were estimated to be 73.0, 9.7, and 6.9
mg m−2, respectively, corresponding to calcite fluxes of 3.6, 0.5, and 0.3 mg m−2d−1 using Stoke's Law.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
One year records of four current meters moored at two sites off Sanriku (39°26′ N, 142°45′ E and 143°E) have been analyzed.
Mean currents flowed southward to southwestward with velocity 2.5–7.8 cm s−1. The geostrophic velocity appeared to be surface-intensified, and the flows at 500 m depth have a relationship with the 100
m depth temperature distribution, suggesting the influence of the upper layer flows. At a depth of 1500 m and 2500 m, southward
to southwestward flows are thought to be a part of the current flowing southward on the western flank of the Japan Trench.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
13.
Variability in water temperature, salinity and density was investigated based on field measurements near Anzali Port, in the
Southern Caspian Sea in 2008. Seasonal changes of seawater properties were mainly observed through the upper 100 m layer,
while below this layer seasonal variations of the parameters were minor. Vertical structure of the temperature in the southern
coastal waters of the Caspian Sea is characterized by a significant seasonal thermocline between 20–50 m depths with vertical
variation in temperature about 16°C in midsummer (August). Decrease of the thermocline occurs with the general cooling of
the air and sea surface water, and deepening of the mixed layer during late of autumn and winter. Seasonal averages of the
salinity were estimated in a range of 12.27–12.37 PSU. The structure of thermocline and pycnocline indicated agreement between
changes of temperature and density of seawater. Seasonal pycnocline was observed in position of the thermocline layer. 相似文献
14.
The species composition, seasonal abundance, and vertical distribution of mesopelagic fish larvae are described based on discrete
depth sampling from the surface down to 1000 m depth during four cruises at a fixed sampling station in Sagami Bay. The abundances
of total mesopelagic fish larvae in April, July, September, and December were 65.7, 13.6, 118.9, and 17.2 individuals per
10 m2 sea surface, respectively. Twenty species or types of mesopelagic fish larvae belonging to 10 families were collected. Diaphus garmani, Lipolagus ochotensis, Diogenichthys atlanticus, Sigmops gracile, and Maurolicus japonicus were the five most abundant larvae and accounted for 43.1, 14.5, 7.4, 6.3, and 5.9% of the total mesopelagic fish larvae,
respectively. These five species showed clear seasonal changes in abundance, i.e. L. ochotensis, D. atlanticus, and S. gracile larvae mainly occurred during winter— spring; D. garmani and M. japonicus were collected during summer—autumn. No obvious diel vertical migration was found in these larvae. The larvae of D. garmani and M. japonicus were concentrated in the 25–50 and 50–100 m depth layers, respectively. The transforming stage of L. ochotensis, S. gracile, and D. atlanticus occurred at 400–1000 m depth, while their larvae (<8 mm standard length) occurred in the upper 100 m layer, indicating that
metamorphosis of these species takes place in the 400–1000 m layer. Based on the occurrence of mesopelagic fish larvae and
oceanographic processes in Sagami Bay, with the exception of D. garmani and M. japonicus, most larvae are considered to originate from the Kuroshio region where their main spawning grounds are formed. 相似文献
15.
Structure of the phytoplankton communities and primary production in the Ob River estuary and over the adjacent Kara Sea shelf 总被引：1，自引：0，他引：1
The material was collected in the Ob River estuary and over the adjacent shallow Kara Sea shelf between 71°14′0 and 75°33′0N
at the end of September 2007. Latitudinal zoning in the phytoplankton distribution was demonstrated; this zoning was determined
by the changes in the salinity and concentration of nutrients. Characteristic of the phytocenosis in the southern desalinated
zone composed of freshwater species of diatom and green algae were the high population density (1.5 × 106 cells/l), biomass (210 μgC/l), chlorophyll concentration (4.5 μg/l), and uniform distribution in the water column. High primary
production (∼40 μgC/l/day) was recorded in the upper 1.5-m layer. The estuarine frontal zone located to the north contained
a halocline at a depth of 3–5 m. Freshwater species with low population density (2.5 × 105 cells/l), biomass (24 μgC/l), and chlorophyll concentration (1.5 μg/l) dominated above the halocline. Marine diatom algae,
dinoflagellates, and autotrophic flagellates formed a considerable part of the phytocenosis below the halocline; the community
characteristics were twofold lower as compared with the upper layer. The maximal values of the primary production (∼10 μgC/l
per day) were recorded in the upper 1.5-m layer. The phytocenosis in the seaward zone was formed by marine alga species and
was considerably poorer as compared with the frontal zone. The assimilation numbers at the end of the vegetation season in
the overall studied area were low, amounting to 0.4–1.0 μgC/μgChl/h in the upper layer and 0.03–0.1 μgC/μgChl/h under the
pycnocline. 相似文献
16.
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
17.
Naoto Iwasaka Fumiaki Kobashi Yosuke Kinoshita Yuko Ohno 《Journal of Oceanography》2006,62(4):481-492
A seasonal evolution of surface mixed layer in the western North Pacific around 24°N between 143°E and 150°E was observed
by using an Argo float for more than 9 months, from December 2001 through August 2002. The result showed that the mixed layer
deepened gradually in the first two months. It reached its maximum depth of about 130 m at the end of January, after which
the mixed layer varied largely and sometimes the pycnocline below the mixed layer was much weakened until the summer mixed
layer formed in late April. The thin surface mixed layer was maintained during the rest of the observation period. Heat budget
analysis suggests that the vertical and horizontal temperature advections are the two most dominant terms in the heat balance
in the upper layer on time scales from a few days to a month. The vertical motions that are possibly responsible for the vertical
temperature advection are discussed. 相似文献
18.
The Kuroshio near the Luzon Strait and circulation in the northern South China Sea during August and September 1994 总被引：3，自引：0，他引：3
Wind data from NCEP and hydrographic data obtained from August 28 to September 10, 1994 have been used to compute circulation
in the northern South China Sea and near Luzon Strait using three-dimensional diagnostic models with a modified inverse method.
The numerical results are as follows: the main Kuroshio is located above 400 m levels near Taiwan’s eastern coast and above
800 m levels away from it. Near Luzon Strait above 400 m levels a branch of the Kuroshio joins with a part of the northward
current, which comes from an area west of Luzon’s western coast and intrudes northwestward, then it branchs into western and
eastern parts near 20°30′ N. The eastern part flows northward into an area east of Taiwan, while its western part continues
to intrude northwestward, flowing through an area southwest of Taiwan. Net westward intruded volume transport through longitude
Section AB at 121°00′ E from 19°00′ N to 21° 43′ N is about 3.5 × 106 m3s−1 in a layer above 400 m levels. The anticyclonic eddies W1 and W3 exist above 700 m levels east of Dongsha Islands and below
200 m levels in the eastern part of the region, respectively. The circulation in the middle region is dominated mainly by
a basin-scale cyclonic gyre, and consists of three cyclonic eddies. Strong upwelling occurs in the middle region. The joint
effect of baroclinity and relief and interaction between wind stress and relief both are important for real forcing of flow
across contours of fH
−1 in effecting the circulation pattern. 相似文献
19.
E. Uchupi W. C. Schwab R. D. Ballard J. L. Cheminee J. Francheteau R. Hekinian D. K. Blackman H. Sigurdsson 《Geo-Marine Letters》1988,8(3):131-138
Still photographs and video images collected along the Neovolcanic Zone of the East Pacific Rise from 10°15′N to 11°53′N show
that recent volcanic sheet flows, possibly less than 100 years old, are superimposed on an older sediment-laden pillow terrane.
This recent activity is restricted to a narrow zone that crosses two topographic highs at 10°55′N and 11°26′N and diminishes
along-axis away from these highs. The association of recent sheet flows with older flows and collapse structures on the overlapping
spreading centers at 11°45′N supports the evolutionary model for the occurrence and evolution of overlapping spreading centers
by MacDonald and others (1986, 1988). 相似文献
20.
夏季南海北部微型浮游动物群落 总被引：3，自引：1，他引：2
根据2014年8月至9月于珠江口至南海中部断面(18°00'~22°00'N,114°00'~116°00'E)的南海北部海域进行采样调查,并进行了微型浮游动物群落分析。共发现微型浮游动物142种,隶属于2门44属,其中砂壳纤毛虫28属78种,占所有发现物种数的54.93%;寡毛类纤毛虫14属59种,占所有发现物种数的41.55%。优势类群为:拟卡金斯急游虫(Strombidium paracalkinsi)、具沟急游虫(Strombidium sulcatum)、维尔伯特急游虫(Strombidium wilberti)和无节幼体(nauplii)。调查区微型浮游动物的丰度介于11.43~959.35 ind/L之间,平均值为264.99 ind/L。微型浮游动物垂直分布总体特点是密集区位于50 m水层,50 m水层之下丰度逐渐减少。表层微型浮游动物丰度高值区位于J5-I1站位之间。断面的香农-威纳指数范围在0.92~4.18之间,平均值为2.77;均匀度指数在0.63~1之间,平均值为0.87。应用典范对应分析(CCA)发现温度和盐度是影响微型浮游动物群落的重要因素。通过对连续追踪站位的调查发现,上层水体微型浮游动物群落丰度随着时间而发生一定的变化,下层水体相对较平缓。微型浮游动物昼夜的垂直丰度变化与叶绿素浓度昼夜变化大致相符。 相似文献