Michinobu Kuwae

Michinobu Kuwae
Ehime University

About

54
Publications
6,245
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734
Citations
Citations since 2016
22 Research Items
505 Citations
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
Introduction
Skills and Expertise

Publications

Publications (54)
Article
Full-text available
To reconstruct the historical trend of lake productivity and trophic status in mountain lakes over the past 60 years, we examined the diatom and cladoceran zooplankton remains, fossil pigments, and organic geochemical proxies in a sediment core from Lake Yamanaka, Japan. The fluxes of fossil pigments and total diatom valves, as well as diatom assem...
Preprint
Copepods play a key trophic role as secondary producers in transferring primary production to higher trophic levels such as fish. Copepod production significantly contributes to successful fish recruitment. Despite their importance, knowledge of their dynamics over several decades remains limited due to the difficulty to obtain long-term data serie...
Article
Plastic budgets in the marine environment and their long-term trends are yet to be fully understood. Measuring the accumulation rates in bottom sediments is crucial to solving the riddle of missing ocean plastics. Previous studies based on coastal sediment cores have found that accumulation rates have increased with increases in plastic production...
Article
Full-text available
Plutonium (Pu) has been used as a mid-twentieth century time-marker in various geological archives as a result of atmospheric nuclear tests mainly conducted in 1950s. Advancement of analytical techniques allows us to measure 239Pu and 240Pu more accurately and can thereby reconstruct the Pacific Pu signal that originated from the former Pacific Pro...
Preprint
Underwater sediments are a natural archive of biological information. Reconstruction of past fauna has been conducted for various taxonomic groups using morphological remains and DNA derived from these remains. However, information on past occurrences of fish species, the top predator of lake ecosystems, could have been reproduced only in exception...
Conference Paper
Full-text available
Since the industrial revolution, Lake Biwa (Japan) has been subjected to multiple stressors of human origins causing alterations in the composition and function of its resident biota and thus its ecosystem services. Lake eutrophication in the 1960s, the manipulation of lake water level since 1990s and concomitantly rising of water temperatures have...
Article
Full-text available
Spheroidal carbonaceous particles (SCPs) are carbonaceous fly ash particles produced solely from industrial fossil fuel combustion. SCPs in sediments can be an indicator of past industrialization. We examined the sedimentary SCP record in Beppu Bay, southern Japan, and compared this record to historical trends of industrial activity and monitoring...
Article
Full-text available
Stratigraphic cluster analysis using aquatic palynomorphs preserved in the core sediments revealed a rapid eutrophication due to anthropogenic activities from the mid 1960s in Beppu Bay, East Kyushu, Japan. These assemblages were divided into three major units: BP-I, BP-II and BP-III, and also only dinoflagellate cyst assemblages were divided into...
Article
Full-text available
Little is known about the dynamics of marine food chains spanning primary to higher trophic levels on centennial and longer timescales, especially where the supply of dissolved iron limits primary productivity. To elucidate the long-term dynamics of biological productivity in the Coastal Oyashio (CO), which is a major pathway for transporting disso...
Article
The timing and magnitude of coastal marine degradation in East Asia during a possible transition from the Holocene to the proposed Anthropocene have still not been quantified with well-dated proxy records over centennial-to-millennial timescales. This study uses multi-proxy sedimentary records to address this issue and to document biological and en...
Article
The occurrence of 209 PCB congeners was determined in a sediment core dated between 1930 and 2019 from Lake Biwa, a typical temperate monomictic lake in Japan. Concentrations of total PCBs ranged from 5.3 to 48 ng/g dry weight (dw), showing a highest peak at the 1960s to 1970s. The temporal trend of total PCBs in this sediment core generally matche...
Article
The development of rapid and efficient analytical method for the determination of legacy and current-use brominated flame retardants (BFRs) has been performed due to environmental concern related to these pollutants. In the present study, we used an automated clean-up device equipped with pre-packed micro-column sets (containing sulfuric acid impre...
Article
Contamination levels and temporal trends of polybrominated diphenyl ethers (PBDEs) and some alternative brominated flame retardants (BFRs) were examined in a dated sediment core from the deepest part of the Beppu Bay, southwestern Japan. PBDEs were found in the upper layers of 0–15 cm depth at concentrations ranging from 5200 to 32,600 pg g–1 with...
Article
Full-text available
Far too little is known about the long-term dynamics of populations for almost all macro-organisms. Here, we examined the utility of sedimentary DNA techniques to reconstruct the dynamics in the “abundance” of a species, which has not been previously defined. We used fish DNA in marine sediments and examined whether it could be used to track the pa...
Article
Contamination levels and profiles of mono- to deca-chlorinated biphenyls (PCBs) were characterized in a sediment core dated in 1954–2011 from Beppu Bay, southwestern Japan, providing a comprehensive and detailed picture on the environmental occurrence, temporal trends, and emission sources of these pollutants in the study area. Concentrations of to...
Article
Egg dormancy is a key life history strategy in copepods to temporarily escape catastrophic or repetitive detrimental events and ensure permanent colonization. In Lake Biwa, although the copepod Eodiaptomus japonicus dominates the zooplankton community year-round, it has been known to produce resting eggs, yet little is known about its dormancy. To...
Article
Paleorecords of pelagic fish abundance could better define the nature of fishery productivity dynamics and help understand responses of pelagic fish stocks to long-term climate changes. We report a high-resolution record of sardine and anchovy scale deposition rates (SDRs) from Beppu Bay, Southwest Japan, showing multidecadal and centennial variabi...
Article
In this study, we revised eruptive ages, especially the Aso and Yufu volcanoes, central Kyushu, by analyzing a sediment core of southwestern Beppu Bay, southwest Japan, where undisturbed sediments are continuously deposited in a dysoxic basin. We identified two ash-fall layers in the sequence covering the last ca. 3000 years by using the refractive...
Article
We examined fossil pigments in a ²¹⁰Pb-dated sediment core to document the temporal variations in phytoplankton biomass over the past 150 years in a semi-enclosed bay, Beppu Bay, in the western Seto Inland Sea, Japan. The flux of fossil pigments was used as an index of phytoplankton biomass, which we reconstructed after removing the effect of post-...
Article
Lignins have been used as a biomarker to explore changes in terrestrial organic matter input into lakes and to investigate past watershed vegetation. Burial of organic carbon (OC) in lake sediments, an important component of the global C cycle, is likely associated with the terrestrial OC input. However, few studies have explored changes in terrest...
Article
Strike-slip basins are one of the most important accumulation spaces for sediment of terrigenous, biogenic, and volcanic origins, and generally include large amount of event deposits. Although these event deposits are important basin filling process, research on this topic, particularly the effects of event deposits, is insufficient. In this study,...
Article
Centennial-scale variability of the East Asian winter monsoon during the Holocene is poorly understood because suitable archives and proxies are lacking. Here we present a high-resolution (∼30-yr spacing) planktonic foraminiferal δO18 record of Neogloboquadrina incompta (dextral form), which reflects sea surface temperature during the winter season...
Article
Full-text available
Phospholipid-derived fatty acids (PLFA) and respiratory quinones (RQ) are microbial compounds that have been utilized as biomarkers to quantify bacterial biomass and to characterize microbial community structure in sediments, waters, and soils. While PLFAs have been widely used as quantitative bacterial biomarkers in marine sediments, applications...
Article
Full-text available
We analyzed the lithology, magnetic susceptibility, bulk density, and X-ray radiographs of 14 sediment cores (1-9 m long) from Beppu Bay in the western Seto Inland Sea, Japan, to establish the late Holocene stratigraphy in the deepest part of the bay and to develop an age-depth model for the sediments there. The cores contained 18 thick (major even...
Article
The oxygen isotopic composition (δ18O) of planktonic foraminiferal shells in seafloor sediment provides information on past surface oceanography. Knowledge of seasonal and depth habitat, as well as the δ18O disequilibrium (vital effect), is essential to constrain the interpretation of sedimentary δ18O. Here, we present a 1-year time series of plank...
Article
Full-text available
In this study, we examined the biomass and community structure of sediment bacteria from marine sediments using bacterial phospholipid-derived fatty acids (PLFA) analysis and respiratory quinone profiling method. We also examined relationship between organic carbon contents and concentrations of each biomarker in the sediments. Bacterial PLFAs and...
Article
Full-text available
In order to elucidate the organic and sulfur geochemical processes of surface sediments associated with oxic/anoxic conditions, we have examined the relationship between the spatial distribution of sedimentary δ13C, δ15N, TOC, TN, TS, C/N ratio, and C/S ratio and environmental variables in Beppu Bay, Japan.The results of the principal component ana...
Article
Full-text available
Concentrations of 18 elements, including Sb, In, Sn, and Bi, were measured in sediment cores from two pristine alpine lakes on Mount Hachimantai, northern Japan, representing the past 250 years. Vertical variations in concentrations are better explained by atmospheric metal deposition than by diagenetic redistribution of Fe and Mn hydroxide and org...
Article
Full-text available
Concentrations of 18 elements, including Sb, In, Sn, and Bi, were measured in sediment cores from two pristine alpine lakes on Mount Hachimantai, northern Japan, representing the past 250years. Vertical variations in concentrations are better explained by atmospheric metal deposition than by diagenetic redistribution of Fe and Mn hydroxide and orga...
Article
Full-text available
Atmospheric dust has wide-reaching effects, not only influencing climate conditions, but also ecosystems. The eastern region of the Asian continent is one of the largest emitters of dust in the world, and recent economic growth in the region has been accompanied by an increase in anthropogenic emissions. However, the effects of increased Asian dust...
Article
Full-text available
a b s t r a c t We present a mathematical model of the maintenance of polymorphism of fluvial and amphidromous types in a fish population. Downstream drifting of offspring after hatching and their subsequent upstream migration have an important effect on the maintenance of an upstream population. This model, which assumes a linear relationship of o...
Article
Glacial–interglacial scale climate variability in the tropical Pacific is often discussed with reference to modern El Niño-Southern Oscillation (ENSO). However, proxy records show diverse results and result in inconsistent interpretations. To investigate changes in the thermocline depth of the western Pacific warm pool (WPWP), which is strongly rel...
Article
Full-text available
An apparent temporal increase in Mn and As in a thin surface layer (ca. 2 cm) of sediments in Lake Biwa, Japan, was observed by comparing depth profile data from 1977 and 2009. By our estimation, several thousand tonnes of Mn and a few hundred tonnes of As newly accumulated during the 32 years to 2009. Given various methodological concerns and geoc...
Article
Full-text available
Recently in East Asia the amount of fossil fuel combustion have increased with economic growth. It has caused a problem of trans-boundary air pollution in the whole of eastern Asia. Furthermore, Asian dust storms contribute episodically to the global aerosol load. However, the effects of increased Asian dusts on aquatic ecosystems are not well unde...
Article
It is widely accepted that atmospheric carbon dioxide concentration is rapidly increasing over the last 200 years. Mean air temperature has been increased by 1.15 degreeC in the last 100 years in the Japanese Islands. Although sea surface water temperature (SST) warming of the open ocean surrounding the Japanese Islands has been discussed, global w...
Article
In order to unravel teleconnection patterns on secular and low-frequency variability of fisheries productivity and climates, we reconstructed fish scale deposition rates (SDR, numbers cm-2 yr-1) for Japanese sardine and anchovy and TEX86-derived temperature from anoxic bottom sediments in Beppu Bay, southwest Japan. Japanese sardine and anchovy pri...
Article
Full-text available
Variations in sea surface temperature (SST) and vertical thermal structure in the western subtropical North Pacific, which has the largest air-sea heat flux of the world's oceans, provide insights into the mechanisms of climate change related to air-sea interactions. Here, we present planktonic δ18O and Mg/Ca records from the western subtropical gy...
Article
This study determined the factors contributing to the spatial distribution of 14 metal concentrations in the surface sediments of Beppu Bay on the basis of comparisons of the organic geochemical properties and environmental parameters through principal component analysis (PCA) and redundancy analysis (RDA). The results of PCA and RDA showed that th...
Article
We examined algal remains and fossil pigments in 210Pb-dated sediment cores from Lake Biwa to explore historical changes in the phytoplankton community of the lake over the past 100years and to identify environmental factors that caused those changes. Fluxes of fossil pigments and algal remains were very low before the 1960s, but increased through...
Article
Full-text available
To assess abnormal warming of temperature in southwest Japan's coastal seas during the twentieth century, we developed a 200 yr interannually resolved record of planktonic and benthic foraminiferal Mg/Ca-based temperature using neritic coastal sediment cores. The winter to late spring bottom temperature (50 m) record, based on benthic foraminiferal...
Data
Full-text available
To assess abnormal warming of temperature in southwest Japan's coastal seas during the twentieth century, we developed a 200 yr interannually resolved record of planktonic and benthic foraminiferal Mg/Ca-based temperature using neritic coastal sediment cores. The winter to late spring bottom temperature (50 m) record, based on benthic foraminiferal...
Article
Full-text available
Pinctada fucata martensii mantle tissue and gut contents were examined as baseline indicators of carbon and nitrogen isotope composition at six stations in the Uwa Sea, Japan. Substantial variations in δ13C and δ15N values of oysters among stations were observed, with δ13C being consistently lower at Hiburi Island (−18.1‰) than at other stations (−...
Article
Full-text available
We estimated the composition of two food sources for the cultured pearl oyster Pinctada fucata martensii using stable isotopes and stomach content analysis in the coastal areas of the Uwa Sea, Japan. The δ13C values of oysters (−17.5 to −16.8‰) were intermediate between that of particulate organic matter (POM, −20.2 to −19.1‰) and attached microalg...
Article
In order to detect responses of primary productivity in Japanese coastal embayments to climate and watershed changes for the last 500 years, we unraveled sedimentary records of δ13C, δ15N, TOC, TN, and C/N ratio in the north basin of Kagoshima Bay (KB). Based on principal component analysis of these geochemical data, primary component (PC) 1 that e...
Article
Full-text available
In order to examine the responses of primary productivity in the southern coastal sea of Japan to the Pacific Decadal Oscillation (PDO) in the 20th century, sedimentary records of diatom productivity (diatom valve fluxes) were reconstructed using core samples from the Bungo Channel (BC) in southwest Japan. The record of the Thalassionema spp. flux—...
Article
Full-text available
To reconstruct the pattern of past climate change in central Japan during the last 140 kyr, total planktonic diatom valve concentrations (valves g–1) and fluxes (valves cm–2 year–1) of total planktonic diatoms flux (PVF) and individual species were examined using a 140-m core taken from Lake Biwa, Shiga Prefecture. Most records had a sample resolut...
Article
Full-text available
Detailed diatom records from a 140-m sediment core with a time resolution of approximately 1000–1500 yr were obtained from Lake Biwa to examine possible correlations between diatom concentrations and paleoclimatic changes during the last approximately 400 ka. In the sediments, the diatom assemblages are generally dominated by planktonic diatoms. Th...
Article
抄録 岐阜県の深坂湿原で掘削された13 mのコア試料(最終氷期以降)を用いて珪藻分析を行った.珪藻化石群集解析から古環境変遷に関する以下の結果が得られた.最終氷期の3.0~1.2万年前, 水域は主に富栄養の中性~アルカリ性を呈するある程度の開水域をもった池沼を形成していた.その間の2.5~2.4万年前と1.6~1.5万年前には湿性植物が繁茂する高層湿原の池塘あるいは低層湿原を短期間形成していた.池沼を形成していた頃, 水域は比較的低水温であったことが示唆され, 湿原を形成していた時期は比較的高水温であったことが示唆される.これは最終氷期の気温変動と関連しているかもしれない.一方, 1.2~0.4万年前, 水域は湿性植物が繁茂する高層湿原の池塘あるいは低層湿原を形成していた.この時期, 水域は...
Article
Full-text available
In 1986, Takashima-oki core boring was carried out in the central part of Lake Biwa. The sediment samlpes are composed mainly of silty clay sediments extending over the past c400 000 yr. The sediments are intercalated with many volcanic ash layers, and thus are rich in time control. We analysed for diatom with high-resolution on the sediments, and...
Article
Full-text available
Pinctada fucata martensii mantle tissue and gut contents were examined as baseline indicators of carbon and nitrogen isotope composition at six stations in the Uwa Sea, Japan. Substantial variations in d13C and d15N values of oysters among stations were observed, with d13C being consistently lower at Hiburi Island (� 18.1&) than at other stations (...

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