19 Result(s)
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Article
Fuminori Hashihama
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Article
Temporal variations in the surface primary productivity and their causes at a station F3 in the inner Tokyo Bay
To investigate temporal variations in primary productivity in Tokyo Bay, the surface water fixation rates of inorganic carbon by phytoplankton were measured using 13C under simulated in situ conditions at approxi...
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Seasonal variation in alkaline phosphatase activity in the central part of Tokyo Bay, 2013
In surface water of the eutrophic Tokyo Bay, the dissolved inorganic phosphorus (DIP) concentration has decreased in recent decades. DIP is generally utilized by phytoplankton; however, under low DIP condition...
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Succession of three dominant diatoms, Skeletonema, Thalassiosira, and Pseudo-nitzschia in the inner area of Tokyo Bay from 2003 to 2017
The composition of the phytoplankton community in Tokyo Bay was analyzed using samples collected monthly at 0 and 5 m depths from 2003 to 2017, along with environmental factors. Three diatom genera—Skeletonema, T...
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The origin and characteristics of dissolved organic carbon in the highly urbanized coastal waters of Tokyo Bay
In highly urbanized coastal waters, sewage treatment plant (STP) effluent comprises an increasingly large percentage of surface water supplies. However, the impacts of effluent organic matter on receiving rive...
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Effects of cyanate enrichment on growth of natural phytoplankton populations in the subtropical Pacific
Cyanate is a simple nitrogen-containing organic compound that occurs in surface water at subnanomolar to nanomolar concentrations. To examine the possibility of cyanate as a source of nitrogen for phytoplankto...
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Open AccessA global ocean dissolved organic phosphorus concentration database (DOPv2021)
Dissolved organic phosphorus (DOP) concentration distributions in the global surface ocean inform our understanding of marine biogeochemical processes such as nitrogen fixation and primary production. The spat...
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Estimated ammonium regeneration potentials of two common euphausiid species (Euphausia superba and E. crystallorophias) off Adélie Land, East Antarctica, in austral summer, 2008
Zooplankton contribute to nitrogen regeneration for primary productivity via ammonium excretion. To improve our understanding of the biogeochemical role of zooplankton in the Southern Ocean, ammonium excretion...
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Reply to: Questioning High Nitrogen Fixation Rate Measurements in the Southern Ocean
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Open AccessNanomolar phosphate supply and its recycling drive net community production in the subtropical North Pacific
Seasonal drawdown of dissolved inorganic carbon (DIC) in the subtropical upper ocean makes a significant contribution to net community production (NCP) globally. Although NCP requires macronutrient supply, sur...
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Phytoplankton growth and grazing mortality through the oligotrophic subtropical North Pacific
The subtropical North Pacific has been historically considered as a stable and homogenous oligotrophic marine ecosystem. The consistently low phytoplankton biomass has been attributed to a close balance betwee...
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Open AccessElevated turbulent and double-diffusive nutrient flux in the Kuroshio over the Izu Ridge and in the Kuroshio Extension
While the Kuroshio is known to be a nutrient stream, as these nutrients are in dark subsurface layers, they are not immediately available for photosynthesis unless they are supplied to the sunlit surface layer...
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Biological nitrogen fixation detected under Antarctic sea ice
Nitrogen fixation is the primary source of reactive nitrogen in the ocean. Most ecological models do not predict nitrogen fixation in the Antarctic Ocean because of the low availability of iron and high abunda...
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Basin-scale distribution of NH4 + and NO2 − in the Pacific Ocean
We used more than 25,000 nutrient samples to elucidate for the first time basin-scale distributions and seasonal changes of surface ammonium (NH4 +) and nitrite (NO2 −) concentrati...
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Liquid waveguide spectrophotometric measurements of arsenate and particulate arsenic, as well as phosphate and particulate phosphorus, in seawater
Sensitive methods for the determination of arsenate and particulate arsenic (PAs), as well as phosphate and particulate phosphorus (PP), in seawater are described. The method for arsenate and phosphate was est...
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Comparison of community structures between particle-associated and free-living prokaryotes in tropical and subtropical Pacific Ocean surface waters
The subtropical and tropical regions of the Pacific Ocean are less productive than other oceanic regions. Although particle association should be an important strategy for heterotrophic prokaryotes to survive ...
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Distribution of mixotrophic nanoflagellates along the latitudinal transect of the central North Pacific
To elucidate the ecological importance of mixotrophic nanoflagellates in the open ocean and the environmental factors that regulate their abundance, we surveyed latitudinal distributions of autotrophic, mixotr...
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Sensitive determination of enzymatically labile dissolved organic phosphorus and its vertical profiles in the oligotrophic western North Pacific and East China Sea
Trace concentrations of labile dissolved organic phosphorus (LDOP) in oligotrophic seawater were measured by use of an enzymatic procedure and a nanomolar phosphate analytical system consisting of a gas-segmen...
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Light acclimation states of phytoplankton in the Southern Ocean, determined using photosynthetic pigment distribution
In high-latitude waters such as the Southern Ocean, the primary production of phytoplankton supports the ecosystem. To understand the photo-acclimation strategy of such phytoplankton within cold environments, ...
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Temporal variation in phytoplankton composition related to water mass properties in the central part of Sagami Bay
Temporal variations in water mass properties and the composition of phytoplankton pigments in the central part of Sagami Bay were investigated by monthly observations from June 2002 to May 2004. Eleven pigment...
