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141.
Direct injection of CO(2) into the deep ocean is receiving increasing attention as a way to mitigate increasing atmospheric CO(2) concentration. To assess the potential impact of the environmental change associated with CO(2) sequestration in the ocean, we studied the lethal and sub-lethal effects of raised CO(2) concentration in seawater on adult and early stage embryos of marine planktonic copepods. We found that the reproduction rate and larval development of copepods are very sensitive to increased CO(2) concentration. The hatching rate tended to decrease, and nauplius mortality rate to increase, with increased CO(2) concentration. These results suggest that the marine copepod community will be negatively affected by the disposal of CO(2). This could decrease on the carbon export flux to the deep ocean and change the biological pump. Clearly, further studies are needed to determine whether ocean CO(2) injection is an acceptable strategy to reduce anthropogenic CO(2). 相似文献
142.
Tomoko Yamamoto 《Marine Ecology》2004,25(1):35-49
Abstract. Natural prey composition and prey selectivity of the muricid snail Muricodrupa fusca (Küster), which forages on a wide range of prey, was investigated. Natural prey composition was evaluated through correcting the apparent diet (the result of observations of the feeding behavior) by the handling time, which was determined by laboratory analysis. The apparent diet and the natural diet should generally differ because prey items that require a longer handling time will be observed with higher frequencies. Multiple regression equations were derived to relate the handling time to prey size, predator size and water temperature. A large discrepancy in the apparent versus natural diet of M. fusca was found in prey species composition and prey size. They foraged on at least 11 species of sessile and mobile prey including six limpet species, and mainly preyed on Siphonaria spp. and Lottia spp. in the field. By comparing the percentage of the natural diet to that of prey abundance in the field, M. fusca preferred Siphonaria spp. and Lottia spp. and did not select the other prey species. The selectivity of this predator was explained by optimal foraging theory and antipredator defenses of some limpet species. The relationships among attacking methods, handling time and prey selectivity are also examined. 相似文献
143.
Hiroshi Miyake Mitsugu Kitada Shinji Tsuchida Yoko Okuyama & Ko-ichi Nakamura 《Marine Ecology》2007,28(1):86-92
Hydrothermal vent animals were kept and displayed at atmospheric pressure with an artificial hydrothermal vent system in Enoshima Aquarium, Fujisawa, Kanagawa, Japan. The artificial hydrothermal vent system was composed of a main rearing tank, a heating tank, a hot water outlet with added Na2S as the source of H2S, and added CO2 for chemosynthetic bacteria and pH regulation. When the need arises, a dissolved oxygen control unit and submersible heaters can be attached. We are now rearing hydrothermal vent crabs (Austinograea yunohana), hydrothermal vent galatheid crabs (Shinkaia crosnieri), vestimentiferan tubeworms (Lamellibrachia satsuma), hydrothermal vent shrimp (Opaepele spp.), hydrothermal vent barnacles (Ashinkailepas seepiophilia and Neoverruca sp.), and tonguefish (Symphurus sp.). In the artificial hydrothermal vent tank, shrimp and crabs have been observed to cluster close to the artificial hydrothermal vent. In particular, large (adult) crabs needed a heat source to live in the aquarium over a long term. Additionally, some species (A. yunohana, S. crosnieri, Opaepele sp. and Symphurus sp.) have spawned and hatched in captivity. It is likely higher water temperatures are needed for egg and larval development compared with temperatures for adult requirements. 相似文献
144.
Propulsion system with flexible/rigid oscillating fin 总被引:1,自引:0,他引:1
Yamamoto I. Terada Y. Nagamatu T. Imaizumi Y. 《Oceanic Engineering, IEEE Journal of》1995,20(1):23-30
The purpose of this paper is to describe the feasibility research on an oscillating fin propulsion control system as a vehicle actuator. The system is designed and constructed in order to be combined with ship models. Tank cruising tests are conducted to confirm the system's feasibility. As a result, several advantages of the oscillating fin system are found. A neural network is successfully applied for an identification of the ship model with the oscillating fin, and its effectiveness is confirmed 相似文献
145.
Sub-Lethal Effects of Elevated Concentration of CO<Subscript>2</Subscript> on Planktonic Copepods and Sea Urchins 总被引:2,自引:0,他引:2
Data concerning the effects of high CO2 concentrations on marine organisms are essential for both predicting future impacts of the increasing atmospheric CO2 concentration and assessing the effects of deep-sea CO2sequestration. Here we review our recent studies evaluating the effects of elevated CO2 concentrations in seawater on the mortality and egg production of the marine planktonic copepod, Acartia steueri, and on the fertilization rate and larval morphology of sea urchin embryos, Hemicentrotus pulcherrimus and Echinometra mathaei. Under conditions of +10,000 ppm CO2 in seawater (pH 6.8), the egg production rates of copepods decreased significantly. The survival rates of adult copepods
were not affected when reared under increased CO2 for 8 days, however longer exposure times could have revealed toxic effects of elevated CO2 concentrations. The fertilization rate of sea urchin eggs of both species decreased with increasing CO2 concentration. Furthermore, the size of pluteus larvae decreased with increasing CO2 concentration and malformed skeletogenesis was observed in both larvae. This suggests that calcification is affected by elevated
CO2 in the seawater. From these results, we conclude that increased CO2 concentration in seawater will chronically affect several marine organisms and we discuss the effects of increased CO2 on the marine carbon cycle and marine ecosystem.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
146.
Toru Kobari Kazuaki Tadokoro Akihiro Shiomoto Shinji Hashimoto 《Journal of Oceanography》2003,59(1):3-10
Geographical variations in prosome length and body weight of Neocalanus copepods (N. cristatus, N. plumchrus and N. flemingeri) were investigated on samples from North-South and East-West transects in the North Pacific during spring to early summer
in 1998 and 1999. Southward and eastward increasing patterns were pronounced for water temperature, although no significant
pattern was observed for chlorophyll a concentrations. All Neocalanus species showed large geographical variations in prosome length and body weight, being smaller in the southern and eastern
waters. Comparing the relationship between prosome length and body weight, large deviations (lower body weight at a given
prosome length) were evident for the eastern specimens of N. cristatus and N. plumchrus. In stepwise regression analysis, the geographical variations of prosome length and body weight revealed a significantly
negative correlation with temperature variations. These results suggest that temperature is a more important environmental
factor than chlorophyll a concentration in its effect on geographical variations in prosome length and body weight of Neocalanus copepods in the North Pacific.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
147.
Tokuo Yamamoto 《Applied Ocean Research》1981,3(1):27-36
The simple, yet versatile numerical technique particularly suitable for investigating the problem of the wave attenuation by moored floating breakwater was recently developed by the author. In order to verift the theory, nearly full scale model tests were conducted in a large wave tank (). Both random waves and monochromatic waves were used to compare the results. A breakwater with a rectangular cross-section and a hydrodynamically shaped «three-cycle cylinderå breakwater were tested. Incident wave spectra were successfully decomposed from the multi-reflected sea spectra. Frequency response functions of transmitted wave, sway, heave and roll motions of the breakwater as well as mooring forces were all experimentally determined and compared with the theory. Generally, excellent agreements between the theory, the random wave tests and the monochromatic wave tests were obtained for the hydrodynamically shaped breakwater. Except near the modal frequencies of body motion generally good agreement between theory and experiment was obtained for the rectangular breakwater. Near the modal frequencies, the body motion was damped by the flow separation at the sharp corners of the rectangular breakwater. Generation of higher harmonics in wave, body motion and mooring forces was observed and measured, but was generally small. The slow drift oscillation and its effects on the performance of the spring moored breakwaters were also small. From the comaprisons of the small scale test and the large scale tests, it was found that the scale effects were negligibly small on the performance of the spring-moored breakwaters. 相似文献
148.
Seok Jin Oh Yang Ho Yoon Tamiji Yamamoto Yukihiko Matsuyama 《Ocean Science Journal》2005,40(4):183-190
We investigated the seasonal variability of free alkaline phosphatase activity in seawater and alkaline phosphatase hydrolysable
phosphorus (APHP) at 3 stations in Hiroshima Bay using alkaline phosphatase extracted from the dinoflagellates Alexandrium
tamarense and Gymnodinium catenatum. The dissolved inorganic phosphorus (DIP) was lower than 1 μM in all samples; the lowest
values were in May. The amount of APHP was high at the surface and bottom waters of all stations in May, showing DIP-depleted
conditions. In August and November, the amount of APHP was much less than the amount of APHP in May, indicating that the availability
of dissolved organic phosphorus (DOP) for these species was low and/or uptake during the dinoflagellate blooming might have
occurred in the area. The results obtained from short-term variations of AP activity might suggest that the growth of dinoflagellates
in this season may be partly supported by the AP produced by other diatoms. 相似文献
149.
Evolution of the composition of seawater through geologic time, and its influence on the evolution of life 总被引:2,自引:2,他引:0
Tsuyoshi Komiya Takafumi Hirata Kouki Kitajima Shinji Yamamoto Takazo Shibuya Yusuke Sawaki Tomoko Ishikawa Degan Shu Yong Li Jian Han 《Gondwana Research》2008,14(1-2):159
The redox state of the surface environment of the early Earth is still controversial, and a detailed and quantitative estimate is still lacking. We carried out in-situ analyses of major, trace, and rare-earth elements of carbonate minerals in rocks with primary sedimentary structures in shallow and deep sea-deposits, in order to eliminate secondary carbonate and contamination of detrital materials, and to estimate the redox condition of seawater through time. Based on the Ce content and anomalies of the carbonate minerals at given parameters of atmospheric CO2 content (pCO2) and Ca content of seawater, we calculated the oxygen contents of shallow and deep seawater, respectively. The results show that the oxygen content of the deep sea was low and constant until at least 1.9 Ga. The oxygen content of shallow seawater increased after 2.7 Ga, but fluctuated. It became quite high at 2.5 and 2.3 Ga, but eventually increased after the Phanerozoic. In addition, the calculation of a high pCO2 condition shows that seawater was more oxic even in the Archean than at present, suggesting a relatively low pCO2 through geologic time.Our detailed calculations from compositions of carbonate minerals in Three Gorge area, south China show a low oxygen content of seawater after the Snowball Earth until the late Ediacaran, an increase in the late Ediacaran, and a significant decrease around the Precambrian–Cambrian and Nemakit/Daldynian–Tommotian boundaries. These variations were possibly caused by global regression and dissolution of methane hydrates. 相似文献
150.
Irvine WM Friberg P Kaifu N Kawaguchi K Kitamura Y Matthews HE Minh Y Saito S Ukita N Yamamoto S 《The Astrophysical journal》1989,342(2):871-875
Observations of nine oxygen- and sulfur-containing organic molecules have been made toward the cold dark clouds TMC-1 and L134N. We have confirmed the presence of para-ketene (H2C2O) in TMC-1, have for the first time observed ortho-ketene, and find a total ketene column density approximately 1 x 10(13) cm-2. Thioformaldehyde (H2CS) is easily detectable in both TMC-1 and L134N, with a column density about 5 times larger in the former source (approximately 3 x 10(13) cm-2). The fractional abundance of ketene is comparable to the predictions of ion-molecule chemistry, while that of thioformaldehyde in TMC-1 is one to two orders of magnitude greater than that expected from such models at steady state. Interstellar sulfur chemistry thus continues to be poorly understood. We set upper limits for the column densities of formic acid (HCOOH), vinyl alcohol (CH2CHOH), methyl formate (HCO2CH3), formamide (NH2CHO), methyl mercaptan (CH3SH), isothiocyanic acid (HNCS), and thioketene (H2C2S) in both sources. 相似文献