Diatoms grow faster using ammonium in rapidly flushed eutrophic Dokai Bay,Japan   总被引：1，自引：0，他引：1  

Kuninao Tada  Marut Suksomjit  Kazuhiko Ichimi  Yui Funaki  Shigeru Montani  Machiko Yamada  Paul J. Harrison 《Journal of Oceanography》2009,65(6):885-891

The importance of the nitrogen source for phytoplankton growth in a highly eutrophic embayment, Dokai Bay, was investigated. The DIN concentration often exceeded 100 μM of which 40–70% was NH₄ ⁺. During two incubation experiments, the natural assemblage of mainly diatoms took up NH₄ ⁺ instead of NO₃ ⁻. The growth of two Skeletonema species isolated in Dokai Bay were significantly faster on NH₄ ⁺ (1.86 and 1.27 div. d⁻¹ respectively) than on NO₃ ⁻ (1.55 and 1.04 div. d⁻¹ respectively). Our results indicated that these diatoms could grow faster by using NH₄ ⁺ compared to NO₃ ⁻ in this eutrophic bay.  相似文献   

Spatial partitioning between species of the phytoplankton-feeding guild on an estuarine intertidal sand flat and its implication on habitat carrying capacity     

Akio Tamaki  Ayumi Nakaoka  Hideki Maekawa  Fumihiko Yamada 《Estuarine, Coastal and Shelf Science》2008,78(4):727-738

The fishery yield of Manila clams, Ruditapes philippinarum, increased considerably in the 1970s but has decreased rapidly since the middle 1980s on extensive intertidal sand flats in Ariake Sound (Kyushu, Japan). A survey conducted in 2004 on a 3.4-km² sand flat located in the central part of the Sound (Shirakawa sand flat) revealed four dominant species: two thalassinidean shrimps (Upogebia major and Nihonotrypaea japonica), which are deep-reaching burrow dwellers with strong bioturbation activities, and two bivalves (Mactra veneriformis and R. philippinarum). All four species belong to a phytoplankton (diatom)-feeding guild. In the late 1970s, the Manila clam population prevailed in high densities over the entire sand flat, whereas its distribution was restricted to the lowest quarter of the shore in 2004. In contrast, the population sizes and zones of occurrence of the other phytoplankton feeders have expanded in the absence of R. philippinarum, perhaps an indication of competitive release. After establishment, effects of the thalassinidean shrimps on sediment stability appear to have further reduced clam abundances. Across the sand flat in 2004, wet weight population biomass estimates for N. japonica, U. major, M. veneriformis, and R. philippinarum (whole body for shrimps and soft tissue for bivalves) were 304, 111, 378, and 234 tonnes, respectively. Based on Manila clam fishery yield records from Shirakawa, the carrying capacity of the Shirakawa sand flat in the late 1970s was estimated to be two times greater than the sum value for the whole phytoplankton-feeding guild in 2004. It is hypothesized that (1) the amount of phytoplankton determines the carrying capacity for the benthic community on the Shirakawa sand flat, with both phytoplankton and benthic biomass at maxima in the late 1970s, and (2) the subsequent increases in competition for space have caused further declines in the Manila clam population biomass to approximately one-eighth of its past value.  相似文献   

Similarity of electrophoretic dissolved protein spectra from coastal to pelagic seawaters     

Namiha Yamada  Eiichiro Tanoue 《Journal of Oceanography》2009,65(2):223-233

Dissolved proteins in seawater samples collected from a coastal area of Tokyo Bay, Sagami Bay and a location off the Kuroshio Current were investigated by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high resolution two-dimensional electrophoresis (2-DE). Four to nine protein bands were detected in SDS-PAGE in the apparent molecular weight (MW) range from 12 kilo Dalton (kDa) to 49 kDa. The 2-DE technique distinguished 10 to 46 protein spots exhibiting isoelectric point (pI)/MW ranging 4.3–9.2/12–63 kDa. The elecrophoretic patterns were similar between the coastal and pelagic samples, as well as previously reported patterns from various pelagic areas. The close similarity of electrophoretic mobility on both SDS-PAGE and 2-DE gels indicates the compositional homogeneity of dissolved proteins in seawater throughout a broad range of marine environments. Proteinaceous dissolved organic matter (DOM) that was unresolved and smeared staining characteristics on both SDS-PAGE and 2-DE gels was first observed in Tokyo Bay waters in the present study and its possible sources are discussed. Although the two protein species, 48 kDa and 39 kDa proteins, have been identified as homologues of Porin P and low molecular weight-alkaline phosphatase of Pseudomonas aeruginosa PAO1, respectively, four strains of P. aeruginosa and two species of Pseudomonas spp. have been newly identified as the source organisms of these proteins using the N-terminal amino acid sequence data determined in previous studies.  相似文献   

Design and Long-Term Monitoring of Tokyo International Airport Extension Project Constructed on Super-Soft Ground   总被引：1，自引：0，他引：1  

K. Morohoshi  K. Yoshinaga  M. Miyata  I. Sasaki  H. Saitoh  M. Tokoro  N. Fukuda  T. Fujii  K. Yamada  M. Ishikawa 《Geotechnical and Geological Engineering》2010,28(3):223-232

To meet the increasing demand for air transportation, Ministry of Land, Infrastructure and Transport had carried out the offshore extension project at Tokyo International Airport (Haneda Airport). The airport should be constructed to be perfectly level, but the ground conditions with very thick layers of super soft dredged soils and need for reclamation made the task very difficult. Because of large amount of consolidation settlement, ground improvement by combined vertical drain method was applied to decrease residual and differential settlement after opening of new airport. This paper is aimed to introduce the design concept and method of ground improvement for this project. In addition the result of ground improvement is keeping satisfactory performance for operating airport confirmed by long-term monitoring for airport facilities.  相似文献   

Vertical zonation and aggregated distribution of the Manila clam on subtidal sand flats in a coastal brackish lagoon along the Sea of Japan     

Katsumasa Yamada  Yasushi Miyamoto  Chisato Fujii  Keiko Yamaguchi  Masami Hamaguchi 《Marine Ecology》2014,35(3):308-318

The Manila clam, Ruditapes philippinarum, has maintained small‐sized populations in a semi‐enclosed brackish lake along the Sea of Japan, the Honjo area of Lake Nakaumi, although the environment and biota of this area have changed dramatically due to a large‐scale reclamation project. There should be underlying processes that enable the restoration of this species from small‐sized populations, such as the existence of source (i.e. reproductive) populations in other areas and depth zones of the lake. However, there has been no robust, properly designed evaluation of the distribution of the Manila clam in the subtidal sand flats. In order to elucidate the possible mechanisms that allow for the persistence of populations of the Manila clam, we examined the spatiotemporal and vertical variation in distributions of 0‐age clams in the subtidal zone of sand flats. Seasonal effects on population variations showed erratic changes among depth zones without a decreasing trend along the depth gradient. Further, many local populations became extinct even in the shallower zones due to seasonal (summer) hypoxia at deeper zones and hypoxia by the accumulation of key benthic species (Asian mussel and decaying macroalgae) in mats at shallower zones. A few surviving local populations were stable with a spatial‐fragmental (patchy) distribution, associated with fragmented accumulations of Asian mussels and macroalgae. Efforts to maintain stable populations and to restore this species in the subtidal area may depend on these small, restricted, patchy local populations. These findings suggest that high fertility and productivity of the Manila clam as well as patchy distribution of small populations may contribute to the maintenance of the population and the avoidance of extinction (by spatially diffusing the risk of extinction) in harsh environments resulting from the reclamation project.  相似文献   

Records of environmental and ecological changes related to excavation in varve sediment from Lake Hiruga in central Japan     

Seto  Koji  Katsuki  Kota  Tsujimoto  Akira  Kitagawa  Junko  Yamada  Kazuyoshi  Suzuki  Yoshiaki 《Journal of Paleolimnology》2022,68(3):329-343

Journal of Paleolimnology - Sub-annual-scale environmental and ecosystem changes since the mid-18th century were reconstructed in a semi-closed lagoon, Lake Hiruga, located along the Sea of Japan...  相似文献   

Hydraulic properties of and pressure-head dynamics in thick pyroclastic-fall deposits in Atsuma,Northern Japan: implications for the role of water in shallow landslides induced by the 2018 Hokkaido Eastern Iburi Earthquake     

Aoki  Toshiya  Katsura  Shin&#;ya  Koi  Takashi  Tanaka  Yasutaka  Yamada  Takashi 《Landslides》2022,19(8):1813-1824

Landslides - The 2018 Hokkaido Eastern Iburi Earthquake triggered numerous shallow landslides on slopes covered with thick pyroclastic-fall deposits. The landslides occurred more frequently on...  相似文献   

Microbial responses using denaturing gradient gel electrophoresis to oil and chemical dispersant in enclosed ecosystems     

Yoshida A  Nomura H  Toyoda K  Nishino T  Seo Y  Yamada M  Nishimura M  Wada M  Okamoto K  Shibata A  Takada H  Kogure K  Ohwada K 《Marine pollution bulletin》2006,52(1):89-95

Microbial responses to the addition of oil with or without a chemical dispersant were examined in mesocosm and microcosm experiments by using denaturing gradient gel electrophoresis of bacterial ribosomal DNA and direct cell counting. When a water-soluble fraction of oil was added to seawater, increases in cell density were observed in the first 24h, followed by a decrease in abundance and a change in bacterial species composition. After addition of an oil-dispersant mixture, increases in cell density and changes in community structure coincided, and the amount of bacteria remained high. These phenomena also occurred in response to addition of only dispersant. Our results suggest that the chemical dispersant may be used as a nutrient source by some bacterial groups and may directly or indirectly prevent the growth of other bacterial groups.  相似文献   

Experimental study on the bidirectional inelastic deformation capacity of U‐shaped steel dampers for seismic isolated buildings          下载免费PDF全文

Diana Ene  Shoichi Kishiki  Satoshi Yamada  Yu Jiao  Yoshinao Konishi  Masao Terashima  Norihisa Kawamura 《地震工程与结构动力学》2016,45(2):173-192

Hysteretic dampers are used to dissipate earthquake‐induced energy in base‐isolated structures by acquiring inelastic deformations, rendering their hysteretic behavior of vital importance. The present paper focuses on investigating the behavior of U‐shaped steel dampers under bidirectional loading; this is significantly different from their corresponding uniaxial behavior. Two main sets of loading tests on full‐scale specimens are conducted in this regard: (i) quasi‐static tests with simple histories and (ii) dynamic tests with realistic loading histories. Based on the results obtained in the quasi‐static tests, an interaction curve that accounts for the reduction of the cyclic deformation capacity is proposed. However, the fidelity of this relation must be assessed under loading conditions similar to those of a seismically isolated structure subjected to an earthquake, which represents the goal of the second set of tests. The results of the dynamic tests validate the proposed interaction curve for estimating the deformation capacity of U‐shaped steel dampers under bidirectional loading. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Detection and temporal variation of Co in the digestive glands of the common octopus, Octopus vulgaris, in the East China Sea     

Takami Morita  Shigeyoshi Otosaka  Kou Nishiuchi  Haruya Yamada  Masayuki Minakawa 《Marine pollution bulletin》2010,60(8):1193-1199

⁶⁰Co were detected in common octopus specimens collected in the East China Sea in 1996-2005. The source of ⁶⁰Co has remained unclear yet. Stable isotope analyses showed that there was no difference in stable Co concentrations between octopus samples with ⁶⁰Co and without ⁶⁰Co. This result showed that the stable Co in the digestive gland of octopus potentially did not include a trace amount of ⁶⁰Co and the source of ⁶⁰Co existed independently. Furthermore, investigations of octopus in other area and other species indicated that the origin of the source of ⁶⁰Co occurred locally in the restricted area in the East China Sea and not in the coastal area of Japan. Concentrations of ⁶⁰Co have annually decreased with shorter half-life than the physical half-life. This decrease tendency suggests that the sources of ⁶⁰Co were identical and were temporary dumped into the East China Sea as a solid waste.  相似文献