Importance of intracellular Fe pools on growth of marine diatoms by using unialgal cultures and on the Oyashio region phytoplankton community during spring     

Koji Sugie  Kenshi Kuma  Satoshi Fujita  Satomi Ushizaka  Koji Suzuki  Tsutomu Ikeda 《Journal of Oceanography》2011,67(2):183-196

We report on the ability for luxury Fe uptake and the potential for growth utilizing intracellular Fe pools for 4 coastal centric diatom isolates and in situ phytoplankton assemblages, mainly composed of diatoms. Iron uptake of the diatom isolates and natural phytoplankton assemblages in the Oyashio region during spring blooms were prevented by adding hydroxamate siderophore desferrioxamine B (DFB). After the addition of DFB, intracellular Fe in the diatom isolates supported 2.4–4.2 cell divisions with 1.2–2.6 Chl a doublings. The intracellular Fe was primarily used for cell generation rather than Chl a production, leading to a reduction in the Chl a cell quota in the Fe-starved cells with time. The metabolic properties of the Fe-starved cells with their cell morphologies were different among species or genera. An on-deck incubation experiment also exhibited 1.9 cell divisions and 0.81 Chl a doublings of phytoplankton after the addition of DFB, also indicating the preference of cell generation over Chl a production. A decrease in the level of cellular Chl a, a main light-harvesting pigment in Fe-starved diatoms, may become a superior survival strategy to protect the cells from high irradiance that can cause photo-oxidative damages through photosynthesis. Such relatively low-Fe with high-light conditions could often occur in surface waters of the Oyashio region from spring to summer.  相似文献   

Transport of oceanic nitrate from the continental shelf to the coastal basin in relation to the path of the Kuroshio   总被引：1，自引：0，他引：1  

Ryo Sugimoto  Akihide Kasai  Toshihiro Miyajima  Kouichi Fujita 《Continental Shelf Research》2009,29(14):1678-1688

Hydrographic and biogeochemical observations were conducted along the longitudinal section from Ise Bay to the continental margin (southern coast of Japan) to investigate changes according to the Kuroshio path variations during the summer. The strength of the uplift of the cold deep water was influenced by the surface intrusion of the Kuroshio water to the shelf region. When the intrusion of the Kuroshio surface water to the shelf region was weak in 2006, the cold and NO₃⁻-rich shelf water intruded into the bottom layer in the bay from the shelf. This bottom intrusion was intensified by the large river discharge. The nitrogen isotope ratio (δ¹⁵N) of NO₃⁻ (4–5‰) in the bottom bay water was same as that in the deeper NO₃⁻ over the shelf, indicating the supply of new nitrogen to the bay. The warm and NO₃⁻-poor shelf water intruded into the middle layer via the mixing region at the bay mouth when the Kuroshio water distributed in the coastal areas off Ise Bay in 2005. The regenerated NO₃⁻ with isotopically light nitrogen (δ¹⁵N=−1‰) was supplied from the shelf to the bay. This NO₃⁻ is regenerated by the nitrification in the upper layer over the shelf. The contribution rate of regenerated NO₃⁻ over the shelf to the total NO₃⁻ in the subsurface chlorophyll maximum layer in the bay was estimated at 56% by a two-source mixing model coupled with the Rayleigh equation.  相似文献   

MORPHOLOGICAL CHANGES IN DEVELOPMENT OF PHARYNGEAL TEETH IN MYLOPHARYNGODON PICEUS     

乐佩琦 《中国海洋湖沼学报》1995,(3)

Adult pharyngeal teeth in Mylopharyngodon piceus are molariform. Based on SEM observations ofthe developing teeth, this paper describes the morphological diversification of pharyngeal teeth in M.piceus. The larval and juvenile teeth are changed from conical to adult molariform teeth through sevenstages. Comparisons are made between each stage and corresponding types in some species of differentsubfamilies in Cyprinidae. It is considered that the ontogenetic resemblances of the pharyngeal teehbear relationship to the phylogeny of cyprinids.  相似文献   

A strong motion database for the chiba seismometer array and its engineering analysis     

Tsuneo Katayama  Fumio Yamazaki  Shigeru Nagata  Lin Lu  Turgay Turker 《地震工程与结构动力学》1990,19(8):1089-1106

A three-dimensional seismometer array was installed in the Chiba Experiment Station of the Institute of Industrial Science, University of Tokyo in 1982. The array system consists of 44 three-component accelerometers densely placed both on the ground surface and in boreholes. A complementary system for the measurement of ground and buried pipe strains was also installed at the same site. The array system has been successfully in operation, and more than 160 earthquakes have been recorded. Considering a wide use of these seismograms, the Chiba array database has recently been created comprising twenty-seven major events. This paper describes the Chiba array system and its strong motion database. Results of engineering analysis using the selected records are also presented.  相似文献   

Adaptive collaborative approaches in natural resource governance: rethinking participation,learning and innovation     

Yayoi Fujita Lagerqvist 《The Australian geographer》2017,48(4):546-547

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Distribution of phytoplankton in the East China Sea in the winter of 1993   总被引：3，自引：1，他引：3  

Ken Furuya  Kiyo Kurita  Tsuneo Odate 《Journal of Oceanography》1996,52(3):323-333

Phytoplankton distribution and its relationship to water masses were investigated in the East China Sea from February 15 to March 10, 1993. Diatoms, dinoflagellates and coccolithophorids were examined by the Utermöhl method. Two distinct phytoplankton assemblages were identified: a shelf and oceanic assemblage. The shelf community was characterized by a high abundance of diatoms, particularly, a benthic diatomParalia sulcata, and the oceanic community by numerical dominance of coccolithophorids and occurrence of surface warm-water species of diatoms. A boundary of both communities was located at the shelf edge that coincided with the shelf side of a Kuroshio front.P. sulcata was the most dominant in the inner shelf area throughout the water column. The occurrence of this species near the surface was considered to be a good indicator of the enhanced vertical mixing driven by winter monsoon. The species survives under extremely low light intensity near the bottom during the stratified periods in summer. During the winter time when light condition at the bottom becomes most unfavorable, resuspension and upward traveling of the species due to enhanced vertical mixing seem to be advantageous to acquire suitable light condition. Because of its predominance, possible importance ofP. sulcata is suggested in material cycling on the shelf, particularly near the bottom.  相似文献   

Extracellular release of photosynthetic products by a pelagic blue-green alga,Trichodesmium thiebautii     

Sooji Shimura  Yukuya Yamaguchi  Yusho Aruga  Yoshihiko Fujita  Shun-ei Ichimura 《Journal of Oceanography》1978,34(5):181-188

Extracellular release of photosynthetic products by a pelagic blue-green alga,Trichodesmium thiebautii, was scrutinized in relation to pre-treatments in¹⁴C-method for measuring the primary productivity.The extracellular release increased markedly by the pre-treatments with such strong fixative solutions as formaldehyde and mercuric chloride. In such a case, the amount of extracellular fraction reached even almost 78 % of the total photosynthates. The extracellular release of photosynthates was dependent both on light intensity and on physiological state of algal cells. When photosynthesis was terminated by a fixative, the extracellular release was noticed even just after the fixation, and it increased with time. Thus, it appears to be difficult to deduce the real photosynthetic production capacity from the amount of cellular fraction only.The amount of extracellular fraction for unfixed samples filtered immediately after the incubation was less than 8 % of the total photosynthetic products inT. thiebautii. This value is nearly comparable to the amount of excretion reported in many cultured algae.  相似文献   

Mesozooplankton responses to iron-fertilization in the western subarctic Pacific (SEEDS2001)   总被引：1，自引：1，他引：1  

Atsushi Tsuda  Hiroaki Saito  Jun Nishioka  Tsuneo Ono 《Progress in Oceanography》2005,64(2-4):237

A mesoscale iron-fertilization experiment was carried out in the western subarctic Pacific during summer 2001. The iron-patch was traced for 14 days after the fertilization, and the abundance and behavior of mesozooplankton were compared with those outside of the patch. The phytoplankton biomass in the patch rapidly increased to over 15 times the initial level by the later half of the observation period, and was composed of large-sized (>10 mm), centric diatoms. Dominant zooplankton species in the upper 200-m depth were large copepods: Neocalanus plumchrus, Neocalanus cristatus, Eucalanus bungii and Metridia pacifica. Mesozoplankton biomass as well as species composition did not change significantly in the patch over the observation period. Furthermore, no changes of vertical distribution or diel vertical migration were observed for any species or stages of mesozooplankton throughout the observation period. However, the abundance of the first copepodite stages of N. plumchrus and E. bungii increased several fold in the patch after the diatom bloom formation compared to the densities outside the patch. The increases of both species are considered to be due to lowered mortality during the egg and nauplius stages. Spawning of N. plumchrus takes place at depth using lipid storage, while spawning of E. bungii takes place in the surface layer supported by grazing. These facts suggest that the relative importance of nauplii in the diets of the large copepods was decreased in the patch by the diatom bloom. Gut-pigment contents of dominant copepods in the patch increased 4–18 times, and the maximum values were observed during the bloom peak. However, the grazing impact on phytoplankton was low throughout the experiment, especially during the bloom period (<6% of the primary production).  相似文献   

Effect of seasonal change in gas transfer coefficient on air–sea CO2 flux in the western North Pacific     

Xuanrui Xiong  Yoshio Masuda  Taketo Hashioka  Tsuneo Ono  Yasuhiro Yamanaka 《Journal of Oceanography》2015,71(6):685-701

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The H i content of star-forming galaxies at z= 0.24     

Philip Lah  Jayaram N. Chengalur  Frank H. Briggs  Matthew Colless  Roberto De Propris  Michael B. Pracy  W. J. G. de Blok  Shinobu S. Fujita  Masaru Ajiki  Yasuhiro Shioya  Tohru Nagao  Takashi Murayama  Yoshiaki Taniguchi  Masafumi Yagi  Sadanori Okamura 《Monthly notices of the Royal Astronomical Society》2007,376(3):1357-1366

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