著者

Nobuhiro Saito Aiko Kayama Yasuhide Nakamura

出版者

Carcinological Society of Japan

雑誌

Crustacean Research (ISSN:02873478)

巻号頁・発行日

vol.51, pp.111-113, 2022-10-19 (Released:2022-10-19)

参考文献数

14

被引用文献数

1

著者

Yasuhide Nakamura Akihiro Tuji Wataru Makino Shin-ichiro S. Matsuzaki Nobuaki Nagata Megumi Nakagawa Noriko Takamura

出版者

The Plankton Society of Japan, The Japanese Association of Benthology

雑誌

Plankton and Benthos Research (ISSN:18808247)

巻号頁・発行日

vol.15, no.1, pp.44-54, 2020-02-28 (Released:2020-03-25)

参考文献数

40

被引用文献数

9

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Neomysis awatschensis is an important prey item for various fishes in Lake Kasumigaura, Japan. There is, however, a contradiction concerning the major food sources of this mysid species: whether “bottom mud”, “particulate organic matter (POM) including phytoplankton”, or “mesozooplankton” is the main diet, and this uncertainty may be due to differences in the methodology used to determine the prey items in previous studies. This study examined the main food sources of N. awatschensis by combining three methods to eliminate methodological biases: DNA metabarcoding, microscopy and stable isotope analysis. Planktonic diatoms and green algae sequences were the main taxa detected by DNA metabarcoding and microscopy on the fecal pellets. The δ15N values of the mysids were similar to those of phytoplankton feeders rather than carnivorous planktonic crustaceans. These results suggest that diatoms and green algae were the major food sources for N. awatschensis in Lake Kasumigaura during the investigation period, and that its trophic level is as low as that of herbivores. However, the partial contribution of other “POM” (e.g., benthic diatoms) is also implied, considering the dispersion in δ13C values. Mesozooplankton prey, such as copepods, were detected both using DNA metabarcoding and microscopy, but they could not be a major food source due to the low nitrogen stable isotopic signature of the mysids. The opportunistic feeding habits of N. awatschensis possibly explain the consistent dominance of this species in the lake, where the ecosystem structure was substantially changed because of successive desalination.

著者

Yasuhide Nakamura Rei Somiya Noritoshi Suzuki Mitsuko Hidaka-Umetsu Atsushi Yamaguchi Dhugal J. Lindsay

出版者

The Plankton Society of Japan, The Japanese Association of Benthology

雑誌

Plankton and Benthos Research (ISSN:18808247)

巻号頁・発行日

vol.12, no.2, pp.95-103, 2017-05-30 (Released:2017-06-06)

参考文献数

46

被引用文献数

3 15

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Optics-based surveys for large unicellular zooplankton were carried out in five different oceanic areas. New identification criteria, in which “radiolarian-like plankton” are categorized into nine different groups, are proposed for future optics-based surveys. The autonomous visual plankton recorder (A-VPR) captured 65 images of radiolarians (three orders: Acantharia, Spumellaria and Collodaria) and 117 phaeodarians (four taxa: Aulacanthidae, Phaeosphaerida, Tuscaroridae and Coelodendridae). Colonies were observed for one radiolarian order (Collodaria) and three phaeodarian taxa (Phaeosphaerida, Tuscaroridae and Coelodendridae). The rest of the radiolarian orders (Taxopodia and Nassellaria) and the other phaeodarian taxa were not detected because of their small cell size (< ca. 400 µm).

著者

Mariko Kanamori Naoki Kondo Yasuhide Nakamura

出版者

Japan Epidemiological Association

雑誌

Journal of Epidemiology (ISSN:09175040)

巻号頁・発行日

vol.31, no.1, pp.43-51, 2021-01-05 (Released:2021-01-05)

参考文献数

47

被引用文献数

2 5

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Background: Recent research suggests that Japanese inter-prefecture inequality in the risk of death before reaching 5 years old has increased since the 2000s. Despite this, there have been no studies examining recent trends in inequality in the infant mortality rate (IMR) with associated socioeconomic characteristics. This study specifically focused on household occupation, environment, and support systems for perinatal parents.Methods: Using national vital statistics by household occupation aggregated in 47 prefectures from 1999 through 2017, we conducted multilevel negative binomial regression analysis to evaluate occupation/IMR associations and joinpoint analysis to observe temporal trends. We also created thematic maps to depict the geographical distribution of the IMR.Results: Compared to the most privileged occupations (ie, type II regular workers; including employees in companies with over 100 employees), IMR ratios were 1.26 for type I regular workers (including employees in companies with less than 100 employees), 1.41 for the self-employed, 1.96 for those engaged in farming, and 6.48 for unemployed workers. The IMR ratio among farming households was 1.75 in the prefectures with the highest population density (vs the lowest) and 1.41 in prefectures with the highest number of farming households per 100 households (vs the lowest). Joinpoint regression showed a yearly monotonic increase in the differences and ratios of IMRs among farming households compared to type II regular worker households. For unemployed workers, differences in IMRs increased sharply from 2009 while ratios increased from 2012.Conclusions: Inter-occupational IMR inequality increased from 1999 through 2017 in Japan. Further studies using individual-level data are warranted to better understand the mechanisms that contributed to this increase.