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1.
Tidal currents observed in a surface layer overlying deep water in Sagami and Suruga Bays frequently have large amplitude in summer and fall. Numerical experiments show that the current amplitude due to the surface tides is below 1.0 cm sec–1 for the semidiurnal and diurnal constituents in the inner region of the two bays. The observed current amplitudes are larger than the calculated ones due to the surface tides. Therefore, the observed tidal currents are indicated to be due mainly to the internal tides. In addition, the semidiurnal currents dominate the diurnal currents in Sagami Bay, while the opposite occurs in Suruga Bay. These results suggest that the prevailing periods of the internal tides differ between the two bays,i.e., the internal tide has a semidiurnal period in Sagami Bay and a diurnal period in Suruga Bay.  相似文献   

2.
Current measurements in the surface layer in Sagami and Suruga Bays showed existence of significant tidal currents which are considered to be mainly due to internal tides (Inaba, 1982; Ohwaki,ea al., 1991). In addition, the prevailing period of the tidal currents is semidiurnal in Sagami Bay, but diurnal in Suruga Bay. To explain this difference in the prevailing, periods, numerical experiments were carried out using a two layer model. The internal tides are generated on the Izu Ridge outside the two bays. The semidiurnal internal tide propagates into Sagami Bay having characteristics of an internal inertia-gravity wave, while it propagates into Suruga Bay having characteristics of either an internal inertia-gravity wave or an internal Kelvin wave. The diurnal internal tide behaves only as an internal Kelvin wave, because the diurnal period is longer than the inertia period. Thus, the diurnal internal tide generated on the Izu Ridge can be propagated into Suruga Bay, while it cannot propagate into the inner region of Sagami Bay, though it is trapped around Oshima Island, which is located at the mouth of Sagami Bay. The difference in the propagation characteristics between the semidiurnal and diurnal internal tides can give a mechanism to explain the difference in the prevailing periods of the internal tides between Sagami and Suruga Bays.  相似文献   

3.
2001/2002年夏季南极普里兹湾及其邻近海域的浮游植物   总被引：15，自引：4，他引：15       下载免费PDF全文
报道了 2 0 0 1 /2 0 0 2年夏季南极普里兹湾邻近海域 3 7个大面测站浮游植物的调查结果。经初步鉴定共有浮游植物 3门 3 7属 86种 ,其中硅藻在种类和细胞丰度上占绝对优势 ,其次为甲藻。主要优势种为克格伦拟脆杆藻 (Fragilariopsiskerguelensis)、细条伪菱形藻 (Pseu do nitzschialineola)、短拟脆杆藻 (Fragilariopsiscurta)和赖氏束盒藻 (Trichotoxonreinboldii)等南极特有种类和常见种类。调查区浮游植物分为两个群集 ,分布在 6 7°S以南的普里兹湾内的群集主要以克格伦拟脆杆藻、短拟脆杆藻、胡克星脐藻 (Asteromphalushookeri)和南极弯角藻 (Eu campiaantarctica)等南极特有种类和常见种类为主 ;分布在 6 7°S以北的大洋海域的群集主要以细条伪菱形藻、赖氏束盒藻、拟膨胀伪菱形藻 (Pseudo nitzschiaturgiduloides)和羽状环毛藻(Corethronpennatum)等南极常见种为主。调查区浮游植物的平均细胞丰度为 (8796± 2 92 85 )ind/L ,细胞多分布于海水的表层 ,密集区分布在 6 7°S以南的普里兹湾内 ,浮游植物的细胞丰度同硝酸盐的浓度密切相关。调查区浮游植物的多样性程度是低的。  相似文献   

4.
Seasonal variations in the picoplankton community were investigated from June 2002 to March 2004 within the photic zone of Sagami Bay, Japan. The study area was mostly dominated by coastal waters during the warm period (mixed layer water temperature ≥ 18°C). During the cold period (mixed layer water temperature ≤ 18°C), the water mass was characterized by low temperature and high saline waters indicative of the North Pacific Subtropical Mode Water (NPSTMW). Occasionally, a third type of water mass characterized by high temperature and low saline properties was observed, which could be evidence of the intrusion of warm Kuroshio waters. Synechococcus was the dominant picophytoplankton (5−28 × 1011 cells m−2) followed by Prochlorococcus (1−5 × 1011 cells m−2) and picoeukaryotes during the warm period. Heterotrophic bacteria dominated the picoplankton community throughout the year, especially in the warm period. During the Kuroshio Current advection, cyanobacterial abundance was high whereas that of picoeukaryotes and heterotrophic bacteria was low. During the cold period, homogeneously distributed, lower picophytoplankton cell densities were observed. The dominance of Synechococcus in the warm period reflects the importance of high temperature, low salinity and high Photosynthetically Active Radiation (PAR) on its distribution. Cyanobacterial and heterotrophic bacterial abundance showed a positive correlation with temperature. Prochlorococcus and picoeukaryotes showed a positive correlation with nutrients. Picoeukaryotes were the major contributors to the picophytoplankton carbon biomass. The annual picophytoplankton contribution to the photosynthetic biomass was 32 ± 4%. These observations suggest that the environmental conditions, combined with the seasonal variability in the source of the water mass, determines the community structure of picoplankton, which contributes substantially to the phytoplankton biomass and can play a very important role in the food web dynamics of Sagami Bay.  相似文献   

5.
Siphonophores were sampled using stratified 1.67-m2-mouth 330-μm mesh nets during both day- and nighttime in Sagami Bay (35°0.50′N, 139°20′E), off south-eastern Japan during a 9-day period in March 2006, when the Kuroshio Current was in an offshore non-large meander phase. The samples were collected at 50-m intervals spanning from 1,000 m depth to the surface. Fifty-eight species and 11 eudoxid forms of unknown parentage were collected, of which 5 represent first-time records from Japanese waters, and Clausophyes laetmata Pugh and Pagès 1993, Eudoxia cf. galathea Moser 1925 and Lensia panikkari Daniel 1970 were recorded for the first time not only from Japan but from the entire Pacific Ocean. The highest abundance and diversity was found below the thermocline during the day, and above it at night. A second peak in abundance, around 400 m depth, associated with a decrease in diversity, could be linked to the increase in abundance of a single species—Dimophyes arctica (Chun 1897). The siphonophore communities could be related to the different water masses in the Bay, with an important influence of lateral transport of both tropical and subarctic species into the Bay by the different water masses.  相似文献   

6.
Variations in benthic biodiversity owing to bottom trawling were studied in the inshore waters of Parangipettai (Lat.11°24′N; Long. 79°464′E) and Cuddalore (Lat. 11°434′N; Long. 79°494′E), India from February 2009 to January 2010. Four stations each in Parangipettai and Cuddalore were prepared and established. A total of 114 species in Parangipettai and 101 in Cuddalore were found. The population density showed a maximum (10,387 no. m-2) in Parangipettai in the sample collected before trawling and a minimum (40no. m?2) in Cuddalore in the samples collected after trawling. Among the faunal groups, polychaetes topped the list followed by other groups of organisms both in the samples before and after trawling. Shannon diversity varied from 2.23 to 4.24, 1.85 to 3.45; Margalef richness from 3.2 to 5.9, 2.57 to 4.25; Pielou’s evenness varied from 0.79 to 0.94, 0.81 to 0.88 in the samples collected before and after trawling respectively in Parangipettai. In Cuddalore waters, Shannon diversity ranged from 2.15 to 3.85, 1.92 to 3.15; Margalef richness from 2.95 to 5.2, 2.24 to 3.95 and Pielou’s evenness index from 0.84 to 0.91, 0.79 to 0.82 in the samples before and after trawling respectively. Multivariate methods also showed distinct variations in terms of species composition and abundance between regions and samples.  相似文献   

7.
Megalobenthic samples trawled from the bathyal zone in Sagami Bay contain some probable subarctic elements, such asSebastolobus macrochir, Clidoderma asperrimum, Solaster paxillatus, Macoma calcarea, Cryptonatica clausa, Eunatica pallida, Volutomitra alaskana, Paralomis multispina andPandalus hyspinotus, among others. The mechanism and process of invasion of such cold-water species into the deep-sea zone in Sagami Bay are not simple. There are some evidences that these animals are propagating in Sagami Bay. The occurrences of subarctic fish there are not unusual because of their strong swimming ability. The benthic animals that have planktonic larval stages might be dispersed in the same process as in the Oyashio plankton translocated by Oyashio Undercurrent. However, the mechanism and process of dispersions of egg-carrying crustaceans and egg-case producing gastropods remain unanswered. Perhaps, the palaeo-oceanographical and evolutional considerations will help to solve the problem.Contribution B-557 from Tokai Regional Fisheries Research Laboratory.  相似文献   

8.
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   

9.
Intermediate intrusion of low salinity water (LSW) into Sagami Bay was investigated on the basis of CTD data taken in Sagami Bay and off the Boso Peninsula in 1993–1994. In October 1993, water of low temperature (<7.0°C), low salinity (<34.20 psu) and high dissolved oxygen concentration (>3.5 ml I−1) intruded along the isopycnal surface of {ie29-1} at depths of 320–500 m from the Oshima East Channel to the center of the bay. On the other hand, the LSW was absent in Sagami Bay in the period of September–November 1994, though it was always found to the south off the Boso Peninsula. Salinity and dissolved oxygen distributions on relevant isopycnal surfaces and water characteristics of LSW cores revealed that the LSW intruded from the south off the Boso Peninsula to Sagami Bay through the Oshima East Channel. The LSW cores were distributed on the continental slope along 500–1000 m isobaths and its onshore-offshore scales were two to three times the internal deformation radius. Initial phosphate concentrations in the LSW revealed its origin in the northern seas. These facts suggest that the observed LSW is the submerged Oyashio Water and it flows southwestward along the continental slope as a density current in the rotating fluid. The variation of the LSW near the center of Sagami Bay is closely related to the Kuroshio flow path. The duration of LSW in Sagami Bay is 0.5 to 1.5 months.  相似文献   

10.
As part of the research program WEST-COSMIC Phase I (1997–2001), vertical profiles down to the greater depths (0–2000 m or 5800 m) of the plankton community structure composed of heterotrophic bacteria, phytoplankton, protozooplankton and metazooplankton were studied at one station in each subarctic (44°N) and in transitional region (39°N), and two stations in subtropical region (30°N and 25°N); all in 137–155°E in the western North Pacific Ocean. The biomass of all four taxonomic groups decreased rapidly with increasing depths at all stations, although the magnitude of depth-related decrease differed among the groups. As plankton community structure, metazooplankton biomass and bacterial biomass occupied >50% of the total in 0–2000 and 2000–4000 or 5000 m strata, respectively, at subarctic and transitional stations, while bacterial biomass contributed to >50% of the total consistently from 0 through 4800 or 5800 m at subtropical stations. Metazooplankton biomass integrated over the greater depths exhibited a clear latitudinal pattern (high north and low south), but this was not the case for those of the other taxonomic groups. As a component of metazooplankton, an appreciable contribution of diapausing copepods to the metazooplankton was noted at subarctic and transitional stations, but they were few or nil at subtropical stations. As protozooplankton assemblages, heterotrophic microflagellates (HMF) and dinoflagellates were two major components at subarctic and transitional stations, but were only HMF predominated at subtropical stations. From biomass ratios between heterotrophic bacteria, HMF and dinoflagellates, “sinking POC-DOC-heterotrophic bacteria-HMF-heterotrophic dinoflagellates” link was proposed as a microbial food chain operative in the deep layer of the western North Pacific. All results are discussed in the light of latitudinal differences in the structure and functioning of plankton community contributing to the ‘biological pump’ in the western North Pacific Ocean. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

11.
Chaetognaths are an abundant component of the plankton and are usually the most important carnivores. Head or tail damage is often found in chaetognath specimens from the laboratory and the sea. Examination by light and scanning electron microscopy (SEM) of specimens with such damage has revealed that bacterial invasion occurs in chaetognaths under laboratory and natural conditions. Living chaetognaths which cease feeding are found to have large numbers of attached bacteria and some parts of their body become opaque. Once they are attacked in this manner the body appears to be a mass of bacteria. Examination of field samples has shown that similar bacterial attacks occur in the sea. Bacterial growth is common inside the muscle tissue of field specimens. Up to 13.3% of two dominant species of chaetognaths in Suruga Bay are attacked by bacteria.  相似文献   

12.
The uranium content and activity ratio A234U/A238U were determined in open ocean water, marine plankton, marine algae and sea water in the environment in which plankton and algae live. The average uranium content of 3.34±0.28×10−6 g/l and the average activity ratio of 1.13±0.04 were obtained in open ocean water. The uranium contents in plankton and algae were respectively from 1.7 to 7.8×10−7 g/g and 0.4 to 23.5×10−7 g/g on dry basis with the respective concentration factors of 48 to 260 and 10 to 733. The activity ratio in plankton and algae ranged from 1.07 to 1.18 which coincided well with those in the environmental sea water.  相似文献   

13.
The seasonal abundance of the dominant dinoflagellate, Ceratium fusus, was investigated from January 2000 to December 2003 in a coastal region of Sagami Bay, Japan. The growth of this species was also examined under laboratory conditions. In Sagami Bay, C. fusus increased significantly from April to September, and decreased from November to February, though it was found at all times through out the observation period. C. fusus increased markedly in September 2001 and August 2003 after heavy rainfalls that produced pycnoclines. Rapid growth was observed over a salinity range of 24 to 30, with the highest specific rate of 0.59 d−1 measured under the following conditions: salinity 27, temperature 24°C, photon irradiance 600 μmol m−2s−1. The growth rate of C. fusus increased with increasing irradiance from 58 to 216 μmol m−2s−1, plateauing between 216 and 796 μmol m−2s−1 under all temperature and salinity treatments (except at a temperature of 12°C). Both field and laboratory experiments indicated that C. fusus has the ability to grow under wide ranges of water temperatures (14–28°C), salinities (20–34), and photon irradiance (50–800 μmol m−2s−1); it is also able to grow at low nutrient concentrations. This physiological flexibility ensures that populations persist when bloom conditions come to an end.  相似文献   

14.
Current measurements were conducted 10 m below the sea surface near the head of Suruga Bay intermittently from 1970 to 1978. The circulation pattern is usually counterclockwise; northward along the east coast (off Heda and at the mouth of Uchiura Inlet), westward along the north coast (off Fuji), and southwestward along the west coast (off Shimizu). The amplitudes of the four major tidal constituents of current variation, M2, S2, K1 and O1, are much larger than those expected from sea level variations along the coast. The amplitudes of the diurnal constituents of current variation are much larger than those of the semidiurnal constituents, while the amplitudes of the semidiurnal constituents of sea level variation are much larger than those of the diurnal constituents. The observed amplitude of the predominant diurnal constituents exhibit large seasonal changes and tend to increase with the development of the stratification of the upper part of the water in Suruga Bay. These facts strongly suggest that the observed current variations are mainly associated with internal tides in Suruga Bay.  相似文献   

15.
Using a flow cytometer (FCM) onboard the R/V Xuelong during the 24th Chinese Antarctic cruise, picoplankton community structure and biomass in the surface water were examined along the latitude and around the Antarctic Ocean. Salinity and temperature were automatically recorded and total Chla was determined. Along the cruise, the abundance of Synechococcus, Prochlorococcus, pico-eukaryotes and heterotrophic bacteria ranged in 0.001-1.855×108 ind./L, 0.000-2.778￡108 ind./L, 0.002-1.060×108 ind./L and 0.132-27.073×108 ind./L, respectively. Major oceanic distribution of Synechococcus and Prochlorococcus appeared between latitudes 30°N and 30°S. Prochlorococcus was mainly influenced by water temperature, water mass combination and freshwater inflow. Meanwhile, Synechococcus distribution was significantly associated with landing freshwater inflow. Pico-eukaryotes and heterotrophic bacteria were distributed all over the oceans, but with a relatively low abundance in the high latitudes of the Antarctic Ocean. Principal Component Analysis showed that at same latitude of Atlantic Ocean and Indian Ocean, picoplankton distribution and constitution were totally different, geographical location and different water masses combination would be main reasons.  相似文献   

16.
Sagami Bay is a deep-water foreland basin with an average sedimentary rate of approximately 0.1 g/cm2/year. It is an appropriate area to study for better understanding of sedimentary processes in a setting with a high sedimentation rate. Seven multiple core samples, 30-50 cm thick, were obtained from Sagami Bay. Four of the core samples were taken from the Tokyo submarine fan system (Tokyo canyon floor, Tokyo fan valley and its levee, the distal fan margin). Two samples were obtained from the Sakawa fan delta and the adjacent topographic high. The remaining one was from an escarpment of the Sagami submarine fault. Variations in chemical composition can be recognized at every coring site. They show two different sediment sources: the sediments of the Tokyo submarine fan system and those from Sakawa fan delta. Further, there are differences in chemical composition between canyon floor and levees even within the Tokyo submarine fan system. The results suggest that the sedimentary process is strongly controlled not by vertical particle settling but by a hyperpycnal flow process. The proxies obtained from the core samples do not reflect conditions in the water column immediately overlying the sea floor. Rather, they are controlled by conditions on the adjacent continental shelf or/and shallow basins, which are the areas of primary accumulation.  相似文献   

17.
The late stage larvae of five common mytilid bivalves (Mollusca: Pelecypoda: Mytilacea) are described and provisionally identified as Mytilus edulis aoteanus, Modiolus areolatus, Perna canaliculus, Xenostrobus pulex, and Modiolarca impacta. All are readily distinguishable on the basis of larval shell features, including hinge structure. However, one common species, Aulacomya maoriana, was not discerned, and thus the identifications must remain tentative.

The larvae were recovered from plankton samples from Bay of Islands (35° 15’ S, 174° 10’ E), Wellington Harbour (41° 16’ S, 174° 51’ E), and Raumati Beach (40° 56’ S, 174° 58’ E), New Zealand, during 1970–72. Their seasonal occurrences in the plankton are described and related to the condition index of the adults as far as possible.  相似文献   

18.
纳污海水中COD生化降解过程的模拟试验研究   总被引：6，自引：0，他引：6  
1995年5－11月期间,采取渤海湾海水,控制不同的试验水温和不同的有机物起始浓度,采用试验室模拟方法,测定COD生化降解曲线。依据COD降解动力学理论,得出不同环境条件下的COD生化降解动力学参数。经过归纳综合,建立了纳污海水中COD的生化降解动力学参数方程式。试验结果显示,渤海湾天津近岸排海污水COD生化降解过程符合一级反应动力学模型,其降解速率系数足值介于0．023－O．076d-1之间。k值受温度变化的影响较大,温度越高,k值越大。  相似文献   

19.
Over the past 30 years, I have carried out research on the distribution and ecology of marine plankton using research vessels of the Japan Meteorological Agency and the Ocean Research Institute mainly in the Kuroshio and Oyashio areas as well as in Sagami Bay. In this report, some results obtained on the ecological features of blue-green algae, diatoms, chaetognaths etc. in relation to water masses and currents are shown.  相似文献   

20.
Dissolved and labile particulate Zr, Hf, Nb, Ta, Mo and W were determined at stations K1 (51°N, 165°E), K2 (47°N, 160°E), KNOT (44°N, 155°E) and 35N (35°N, 160°E) in the western North Pacific Ocean. A portion of seawater for dissolved species (D) was passed through a 0.2 μm Nuclepore filter and acidified to pH 2.2 with HCl and HF. A portion of seawater for acid-dissolvable species (AD) was acidified without filtration. Labile particulate (LP) species is defined as AD minus D, which represents a chemically labile fraction of particulate species. D-Zr, Hf and Ta increase with depth, Nb shows a slight depletion in surface water, whereas Mo and W have a conservative vertical profile. The concentration range of D-Zr, Hf, Nb, Ta and W is 31–275, 0.14–0.95, 4.0–7.2, 0.08–0.29 and 40–51 pmol kg−1, respectively, whereas that of Mo is 97–105 nmol kg−1. LP-species of Zr, Hf and Ta account for 10–14% of AD in average and increase up to 25% below 4000 m, whereas those for Mo and W are negligible. In contrast, LP-Nb shows maxima (up to 27%) in surface water. We also found that D-Zr/Hf, Nb/Ta and Mo/W mole ratios generally increase in the order continental crust < river water < coastal sea < open ocean.  相似文献   

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