Kozo Takahashi

Kozo Takahashi
Kyushu University | Kyudai · Department of Earth and Planetary Sciences

About

452
Publications
13,562
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4,910
Citations
Citations since 2017
16 Research Items
1316 Citations
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200

Publications

Publications (452)
Chapter
Paleoceanography is developed as a distinct subject in the second half of the twentieth century. This chapter examines the specific methods and results from representative publications that use radiolarians as a paleoceanographic tool. Radiolarians in both modern and in many ancient oceans have displayed distinct, partially, or largely endemic biot...
Chapter
Genetics deals with traits of inheritance from parents to offspring, and is an important source of information for taxonomy and phylogenetics. This chapter provides an overview of macro‐ and microevolutionary relationships of radiolaria based on molecular phylogeny. The rhizarian group has one unique molecular character vs. all other eukaryotes: in...
Chapter
In between the biology and paleontology of radiolarians lie the important subjects of how the living radiolarian biota is transformed by preservation processes into the fossil record, and how this fossil record is recovered for study. The processes of preservation, and the methods used to recover the fossils and prepare them for study, are quite di...
Chapter
This chapter largely reviews the existing knowledge of radiolarian evolution from fossil studies. It discusses macroevolution in purely practical sense. In addition to biologic features, the fossil record of radiolarian evolution has several distinctive characteristics. Some are common to other marine microfossil groups, and distinguish them from m...
Chapter
Radiolarians are a fully planktonic group of organisms, and, although some species are found in coastal waters, the majority of the species are found only, or predominantly, in the pelagic realm of the open ocean. The biologic characteristics of radiolarians reflect both unique adaptations by the group, but equally a variety of constraints that are...
Chapter
This chapter covers two major subjects which are conveniently presented together: the taxonomy of radiolarians, and the basic patterns of their occurrence over time in the fossil record. Our understanding of radiolarian diversity, stratigraphy, geographic distribution of species, and almost all other subjects is built on the basis of radiolarian ta...
Chapter
This chapter covers not only radiolarian research but, to the degree appropriate, developments in various disciplines as they affected the development of radiolarian research. Bibliographic summaries of radiolarian research provide an overview of activity in the field. Radiolarian study really began with the work of C.G. Ehrenberg, who systematical...
Article
Radiolarian biogeography is mostly derived from information gathered from more general studies of the biogeography of plankton. Surface ocean characteristics are by contrast of great importance in radiolarian biogeography and ecology. The characteristic of radiolarian distribution can only be understood by examining the vertical distribution of spe...
Article
Biostratigraphy is a major research theme in radiolarian studies, although its importance varies somewhat according to geologic time interval. This chapter provides an overview of biostratigraphic methods, and how they relate to, and are integrated with, the sciences of physical stratigraphy and geochronology. An elaborate biostratigraphic framewor...
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Full-text available
Phaeodaria, which comprise one group of large, single‐celled eukaryotic zooplankton, have been largely ignored by past marine biological studies because Phaeodaria and their delicate skeletons are liable to collapse. As a result, collection and quantification of specimens are difficult, and seasonal changes of phaeodarian abundance have not been th...
Article
To understand the contribution of carbonate, oxide, organic and siliceous matter to the vertical transportation of elements, sequential chemical leaching was applied to sediment-trap samples collected in and near the Bering Sea. A total of eleven samples representing periods of high to low opal flux were analyzed for elements in carbonate, oxide an...
Article
Full-text available
Our understanding of the paleoceanography of the Bering Sea has been considerably advanced by IODP Expedition 323. The expedition aimed to create a high-resolution record of changes in paleoceanography since the Pliocene in a relatively high-latitude region of the North Pacific, subject to polar amplification. The expedition recovered 660 cores, ma...
Article
Biogenic opal production in the surface water of the Bering Sea shows clear orbital-scale variations such as interglacial highs and glacial lows. In this study, we examined the variation patterns in δ¹⁵N of bulk sediment (δ¹⁵Nbulk) reflecting nitrate utilization, and total organic carbon (TOC) concentration in terms of organic carbon (OC) productio...
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Full-text available
The carbon isotope ratios of organic carbon in settling particles collected in the highly-diatom-productive Bering Sea were determined. Wet decomposition was employed to oxidize relatively fresh organic matter. The amount of unoxidised organic carbon in the residue following wet decomposition was negligible. The δ13C of organic carbon in the settli...
Article
High resolution paleoceanography of the Pliocene–Pleistocene is important in understanding climate forcing mechanisms and associated environmental changes during this major transition from global warmth to the Ice Ages. This is particularly true in high latitude marginal seas such as the Bering Sea. The Bering Sea has been very sensitive to changes...
Article
Coccolithophore fluxes at two sediment trap stations, Station AB in the Bering Sea and Station SA in the subarctic Pacific Ocean, were studied over a nineteen-year (August 1990 to July 2009) interval. Two major species, Coccolithus pelagicus and Emiliania huxleyi, occur at both stations, with Gephyrocapsa oceanica, Umbilicosphaera sibogae, Braarudo...
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We evaluated a 10 year time-series of δ18O and δ13C records from three planktic foraminifers (Neogloboquadrina pachyderma, Globigerina umbilicata, and Globigerinita glutinata) in the Bering Sea and central subarctic Pacific with a focus on their responses to environmental changes. Foraminiferal δ18O followed the equilibrium equation for inorganic c...
Article
Site U1341 in the southern Bering Sea was drilled and cored down to 600 meters below sea-floor (mbsf) during Integrated Ocean Drilling Program (IODP) Expedition 323, covering a nearly complete record of the last 4.3 million years (Myrs). Analyses of the biogenic opal content of sediments at the site provide detailed and useful information on past b...
Article
Late Pliocene to early Pleistocene paleoproductivity changes in the Bering Sea were reconstructed using geochemical concentrations and mass accumulation rates (MARs) of CaCO3, biogenic opal, and total organic carbon (TOC), and sedimentary nitrogen isotope ratios (δ15N) at IODP Expedition 323 Hole U1343E, drilled in the northern slope area (1956 m d...
Article
During the Integrated Ocean Drilling Program (IODP), a total of 41.54 m of basement rock, consolidated volcaniclastic sediment, was recovered beneath a thin sediment cover. The drilled site is at the eastern end of the crestal area of Bowers Ridge, a north and westward sweeping offshoot of the Aleutian Arc into the Bering Sea. The volcanic sequence...
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Full-text available
Accurate knowledge of the extent of biogenic opal preservation in marine sediment cores is important for paleoceanographic reconstructions. The alkaline leaching method is widely employed for %biogenic opal analysis due to its ease and speed. In this study, a revised method for measuring %biogenic opal in sediment from arctic coring expedition samp...
Article
Full-text available
The Nd and Sr isotopes of the acetic-acid-soluble, hydrochloric-acid-soluble, hydrofluoric-acid-soluble (siliceous) fractions of settling particles collected in the highly diatom productive Bering Sea were measured. The siliceous fraction exhibits εNd values higher than that of the acetic acid extractable fraction or that dissolved in North Pacific...