Daisuke Ambe
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View article: Revisiting the distribution and total amount of nitrogen fixation across the Kuroshio
Revisiting the distribution and total amount of nitrogen fixation across the Kuroshio Open
The Kuroshio Current, a western boundary current in the North Pacific Ocean, is regarded as a hotspot of nitrogen fixation that drives marine primary productivity and biogeochemical cycles. However, this assumption is based on limited, spa…
View article: Peer Review #2 of "Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences (v0.1)"
Peer Review #2 of "Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences (v0.1)" Open
Background.Zooplankton plays an important role in the marine ecosystem.A high level of taxonomic expertise is necessary for accurate species identification based on morphological characteristics.As an alternative method to morphological cl…
View article: Peer Review #2 of "Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences (v0.2)"
Peer Review #2 of "Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences (v0.2)" Open
Background.Zooplankton plays an important role in the marine ecosystem.A high level of taxonomic expertise is necessary for accurate species identification based on morphological characteristics.As an alternative method to morphological cl…
View article: Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences
Improving taxonomic classification of marine zooplankton by molecular approach: registration of taxonomically verified 18S and 28S rRNA gene sequences Open
Background Zooplankton plays an important role in the marine ecosystem. A high level of taxonomic expertise is necessary for accurate species identification based on morphological characteristics. As an alternative method to morphological …
View article: Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region
Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region Open
The biological pump that transports carbon from the surface ocean to the ocean interior is an important determinant of ocean carbon absorption from the atmosphere, and of biological activity beneath the euphotic zone. Various factors influ…
View article: 18S rRNA gene sequences of leptocephalus gut contents, particulate organic matter, and biological oceanographic conditions in the western North Pacific
18S rRNA gene sequences of leptocephalus gut contents, particulate organic matter, and biological oceanographic conditions in the western North Pacific Open
Eel larvae apparently feed on marine snow, but many aspects of their feeding ecology remain unknown. The eukaryotic 18S rRNA gene sequence compositions in the gut contents of four taxa of anguilliform eel larvae were compared with the sequ…
View article: Impacts of the Fukushima Nuclear Accident on Fishery Products and Fishing Industry
Impacts of the Fukushima Nuclear Accident on Fishery Products and Fishing Industry Open
On March 11, 2011, a massive earthquake and the resultant gigantic tsunami struck the Tohoku area of Japan (the Great East Japan Earthquake) and damaged many fishing boats and fishing ports. The earthquake and the subsequent tsunami also s…
View article: Spatial and temporal trends in radiocesium and organic matter fraction in sediments from Lake Chuzenji, central Honshu Island, Japan
Spatial and temporal trends in radiocesium and organic matter fraction in sediments from Lake Chuzenji, central Honshu Island, Japan Open
水底放射能測定装置「みなそこ」を用いて，栃木県中禅寺湖の湖底土に吸着した放射性セシウム（137Cs）のマッピング調査を実施した。137Cs蓄積量（Bq/m2）は，水深が深い場所ほど多くなる傾向が認められた。ただし，蓄積量は水深毎に一様ではなく，とくに水深2 m以浅では場所毎の差異が大きいことが示された。化学分画分析により，湖底土の放射性セシウム蓄積量は有機物成分よりも無機物成分でより大きい値を示すことがわかった。
View article: Observations of gut contents of anguilliform leptocephali collected in the western North Pacific
Observations of gut contents of anguilliform leptocephali collected in the western North Pacific Open
ウナギ目葉形仔魚(レプトセファルス)の餌料源を探索するため,西部北太平洋で採集した仔魚26個体の消化管内容物を観察した。いずれの消化管内容物とも,粒径2-10 μmのピコ・ナノプランクトン様の微粒子を多く含み,Alcian Blue染色される多糖類やCoomassie Brilliant Blue染色されるタンパク質で構成された無定形の凝集物であった。本調査結果は,レプトセファルスが外洋に広く存在する植物プランクトン由来のPOMを餌料源のひとつとして利用していることを示唆し…
View article: Radiocesium contamination of aquatic organisms in the estuary of the Abukuma River flowing through Fukushima
Radiocesium contamination of aquatic organisms in the estuary of the Abukuma River flowing through Fukushima Open
In the summer of 2013, we measured the radiocesium ( 134 Cs and 137 Cs) concentrations in aquatic organisms inhabiting the estuary of the Abukuma River, which flows through the Fukushima and Miyagi Prefectures. Radiocesium concentrations i…
View article: Concentrations of <sup>90</sup>Sr and <sup>137</sup>Cs/<sup>90</sup>Sr activity ratios in marine fishes after the Fukushima Dai‐ichi Nuclear Power Plant accident
Concentrations of <sup>90</sup>Sr and <sup>137</sup>Cs/<sup>90</sup>Sr activity ratios in marine fishes after the Fukushima Dai‐ichi Nuclear Power Plant accident Open
Strontium‐90 ( 90 Sr) was released together with radioactive cesium (Cs) from the Fukushima Dai‐ichi Nuclear Power Plant ( FNPP ) accident. Although the total amount of 90 Sr released into the marine environment from the FNPP was estimated…
View article: Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific
Intrusion of Fukushima-derived radiocaesium into subsurface water due to formation of mode waters in the North Pacific Open
The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 released radiocaesium ( 137 Cs and 134 Cs) into the North Pacific Ocean. Meridional transects of the vertical distribution of radiocaesium in seawater were measured along 14…
View article: Investigation of Radiocesium Translation from Contaminated Sediment to Benthic Organisms
Investigation of Radiocesium Translation from Contaminated Sediment to Benthic Organisms Open
We estimated the radiocesium translation from contaminated sediments to benthic organisms off the coast of Fukushima. We conducted field investigations and an experiment with a benthic polychaete (Perinereis aibuhitensis) reared on highly …
View article: Radiocesium Concentrations in the Organic Fraction of Sea Sediments
Radiocesium Concentrations in the Organic Fraction of Sea Sediments Open
Sequential chemical extraction of radiocesium was performed on 22 surface sediment samples to assess radiocesium concentration in the organic fraction of sea sediments (Csorg). Our results showed that Csorg of sea sediments was significant…
View article: Concentration of <sup>134</sup>Cs + <sup>137</sup>Cs bonded to the organic fraction of sediments offshore Fukushima, Japan
Concentration of <sup>134</sup>Cs + <sup>137</sup>Cs bonded to the organic fraction of sediments offshore Fukushima, Japan Open
We conducted a sequential chemical extraction experiment for radiocesium (134Cs + 137Cs) using 21 surface sediment samples and two sets of size-fractionated surface sediment samples collected offshore Fukushima. Our results support earlier…
View article: Evaluating the Probability of Catching Fat Greenlings (Hexagrammos otakii) Highly Contaminated with Radiocesium off the Coast of Fukushima
Evaluating the Probability of Catching Fat Greenlings (Hexagrammos otakii) Highly Contaminated with Radiocesium off the Coast of Fukushima Open
On 1 August 2012, a total of 25,800 Bq/kg-wet of radiocesium (134Cs = 9,800 Bq/kg-wet, 137Cs = 16,000 Bq/kg-wet) was detected in the muscle tissue of two fat greenlings (Hexagrammos otakii) caught approximately 20 km north of the Fukushima…
View article: Three-Dimensional Distribution of Radiocesium in Sea Sediment Derived from the Fukushima Dai-ichi Nuclear Power Plant
Three-Dimensional Distribution of Radiocesium in Sea Sediment Derived from the Fukushima Dai-ichi Nuclear Power Plant Open
This section introduces results of an investigation for radiocesium (134Cs and 137Cs) in sea sediment. The three-dimensional spatial distributions of radiocesium in sea sediment to a 14-cm core depth were surveyed from off the northern par…
View article: Detection of 131I, 134Cs, and 137Cs Released into the Atmosphere from FNPP in Small Epipelagic Fishes, Japanese Sardine and Japanese Anchovy, off the Kanto Area, Japan
Detection of 131I, 134Cs, and 137Cs Released into the Atmosphere from FNPP in Small Epipelagic Fishes, Japanese Sardine and Japanese Anchovy, off the Kanto Area, Japan Open
The artificial radionuclides 131I, 134Cs, and 137Cs released from FNPP were detected in Japanese sardine (Sadinopes melanostictus) and Japanese anchovy (Engraulis japonicus) off the Kanto area of Japan. In the research period from 24 March…
View article: Spatiotemporal Monitoring of 134Cs and 137Cs in Ayu, Plecoglossus altivelis, a Microalgae-Grazing Fish, and in Their Freshwater Habitats in Fukushima
Spatiotemporal Monitoring of 134Cs and 137Cs in Ayu, Plecoglossus altivelis, a Microalgae-Grazing Fish, and in Their Freshwater Habitats in Fukushima Open
Ayu, Plecoglossus altivelis, is a herbivorous fish that is an important fishery resource and a key component of the food web in many Japanese streams. After the Fukushima Daiichi Nuclear Power Plant (FNPP) accident in March 2011, ayu were …
View article: Comparison of the Radioactive Cesium Contamination Level of Fish and their Habitat Among Three Lakes in Fukushima Prefecture, Japan, After the Fukushima Fallout
Comparison of the Radioactive Cesium Contamination Level of Fish and their Habitat Among Three Lakes in Fukushima Prefecture, Japan, After the Fukushima Fallout Open
Levels of radiocesium (134Cs + 137Cs) contamination in lake water, bottom sediment, plankton, and fish were investigated in three geographically separated lakes in Fukushima Prefecture (Lake Hayama, Lake Akimoto, and Lake Tagokura) between…