Marine Biological Research Institute of Japan Co.

Shinagawa-ku, Japan

Marine Biological Research Institute of Japan Co.

Shinagawa-ku, Japan
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Nishi E.,Yokohama National University | Matsuo K.,Yokohama National University | Kazama-Wakabayashi M.,IDEA Consultants Inc. | Mori A.,Marine Biological Research Institute of Japan Co. | And 5 more authors.
Zootaxa | Year: 2014

Eight species of Pectinariidae de Quatrefages, 1866 were recorded from Japan and adjacent waters. We studied four spe-cies of the family and redescribe the poorly known species from the Seto Inland Sea and Ariake Sound, Kyushu based on recently collected material. The species covered in this study are Amphictene japonica (Nilsson, 1928), Lagis bocki (Hessle, 1917), Pectinaria okudai (Imajima & Hartman, 1964) and Pectinaria hiuchiensis Kitamori, 1965. Copyright © 2014 Magnolia Press.

Sasaki H.,Seikai National Fisheries Research Institute | Gomi Y.,Tohoku University | Asai T.,Seikai National Fisheries Research Institute | Asai T.,Marine Biological Research Institute of Japan Corporation Ltd | And 8 more authors.
Terrestrial, Atmospheric and Oceanic Sciences | Year: 2014

The optical properties of colored dissolved organic matter (CDOM) in the Changjiang (Yangtze River) plume water were investigated during the summer of 2009 and 2010. The absorption coefficient of CDOM at 325 nm (aCDOM) increased inversely with decreasing sea-surface salinity (SSS), implying that aCDOM can be used as a natural tracer of Changjiang-diluted water (CDW). This aCDOM vs. SSS relationship, however, differed between 2009 and 2010. For mapping the CDW plume, the aCDOM was retrieved from an ocean-color satellite. Values of SSS were also derived from the satellite-retrieved aCDOM using field-based SSS vs. aCDOM relationships. Satellite observations revealed the temporary variable eastward extension of a high aCDOM, low SSS CDW plume in the central East China Sea (ECS) during the summer. The CDW plume during the summer of 2010 extended southeastward from the mouth of the Changjiang (Yangtze River) to almost 26°N. Moreover, the branch of this southeastward CDW plume was seen to extend northeastward to the eastern ECS where the Kuroshio Current flows northeastward along the shelf break. Subsequently, this branch was distributed around southern Kyushu. Satellite observations revealed this unique dispersal of the CDW plume, which illustrates that the aCDOM and SSS from ocean-color satellite data are useful for monitoring the dispersal of this river-water plume.

Hashihama F.,University of Hyogo | Hashihama F.,Tokyo University of Marine Science and Technology | Umeda H.,Japan National Institute of Polar Research | Umeda H.,Marine Biological Research Institute of Japan Co. | And 8 more authors.
Marine Biology | Year: 2010

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, the vertical distribution profile of photosynthetic pigments was analyzed in the Southern Ocean. Samples were taken along 110°E during the austral summer, and along 150°E and around the edge of the seasonal sea ice of the Antarctic Continent during the austral autumn. Pigment extraction methods were optimized for these samples. The standing crop of chlorophyll a was larger in the region along the edge of the seasonal sea ice than at sampling stations in open ocean areas. Chlorophyll concentration seemed to be dependent on the formation of thermo- and haloclines along the edge of the seasonal sea ice, but not in the open ocean where such clines are less pronounced. The marker pigments fucoxanthin and/or 19′-hexanoyloxyfucoxanthin were dominant at most sampling stations throughout the water column, while other marker pigments such as alloxanthin were quite low. This indicated that diatoms and/or haptophytes were the major phytoplankton in this area. Comparison of the relative ratio of fucoxanthin with that of 19′-hexanoyloxyfucoxanthin allowed some stations to be characterized as either diatom-dominant or haptophyte-dominant. The relative ratio of xanthophyll-cycle pigments (diadinoxanthin plus diatoxanthin) to chlorophyll a was high in surface waters and decreased gradually with depth. This suggests that near the ice edge during summer in the Southern Ocean, both diatoms and haptophytes acclimate to their light environments to protect their photosystems under high-light conditions. © 2010 Springer-Verlag.

Koriyama M.,Saga University | Koga A.,Marine Biological Research Institute of Japan Co. | Seguchi M.,Saga University | Ishitani T.,Marine Biological Research Institute of Japan Co.
Environmental Monitoring and Assessment | Year: 2016

To investigate the seasonal variation of denitrification rate (DR) and clarify the controlling factors of denitrification in the mudflat sediments of Ariake Bay, we conducted field surveys biweekly each month from April 2006 to January 2008. NH4 +-N porewater concentration increased from summer to autumn due to the organic material mineralization under higher sediment temperatures. The seasonal pattern of NH4 +-N flux between sediments and overlying water interface indicated that the mudflat sediments were a source of NH4 +-N in summer. NO3 −+NO2 −-N porewater concentrations were low, ranging from 0.53 to 11.46 μM, and mudflat sediments were sinks of NO3 −+NO2 −-N throughout the year. The mean number of denitrifiers tended to increase in July–September (2188–75,057 MPN g−1) and to decrease in March–May (500–3740 MPN g−1). DR tended to increase in summer, ranging from 76.03 to 990.21 μmol m−2 day−1, and to decrease in winter, ranging from 25.01 to 206.07 μmol m−2 day−1. There was no significant correlation between DR and denitrifier number. Environmental factors influencing DR during the investigation period were determined by multiple regression analysis with the stepwise method. The results indicated that NO3 −+NO2 −-N flux was an important factor in denitrification of mudflat sediments in Ariake Bay. Denitrification was depended on nitrate diffusing from overlying water into sediments under reduced sediment conditions during summer-mid-autumn. On the other hand, in late autumn-winter at Eh>+200 mV and sediment temperature >10 °C, nitrate produced by sediment nitrification was thought to be denitrified subsequently; that is, the coupled nitrification-denitrification may have taken place in the upper layer of mudflat sediments. © 2016, Springer International Publishing Switzerland.

Soga M.,University of Tokyo | Kawahara T.,Japan Forestry and Forest Products Research Institute | Fukuyama K.,Japan Forestry and Forest Products Research Institute | Sayama K.,Japan Forestry and Forest Products Research Institute | And 5 more authors.
Journal of Insect Conservation | Year: 2015

Conversion of terrestrial land for the purposes of agriculture and urban development continues to result in loss and fragmentation of natural habitats. In this study, we focus on butterflies and investigate the relative importance of landscape-level habitat amount (the proportion of woodland area within a landscape), habitat fragmentation (length of woodland edges within a landscape), urbanization (the proportion of urban area within a landscape), and local host plant diversity for butterfly communities in a fragmented landscape in Hokkaido, northern Japan. Butterfly species observed in the field were grouped into woodland and open-land species. The results showed that both landscape and local factors shape the butterfly community. At a landscape-scale, woodland butterflies positively responded to woodland area and negatively to edge density, whereas open-land butterflies showed opposite responses. At a local-scale, positive influences of local host plant diversity on woodland butterflies were evident, but not for open-land species. These results suggest that negative influences of anthropogenic land-use changes on biodiversity could be mitigated by strategies aimed at stopping the spread of woodland edges and providing a wide variety of different host plant species in the landscape. Unfortunately, this study implies that further increases in habitat loss and fragmentation and decline in host plant diversity lead to a homogenization of local biological communities and functions. © 2015, Springer International Publishing Switzerland.

Yamauchi T.,Toyama Institute of Health | Yoshigou H.,Chugai Technos Co. | Itoh T.,Marine Biological Research Institute of Japan Co.
Comparative Parasitology | Year: 2013

ABSTRACT: We present the first record of Parabdella quadrioculata (Annelida: Hirudinida: Glossiphoniidae) from Japan. Leeches were collected from the Japanese pond turtle Mauremys japonica and a Japanese man. Mauremys japonica is a new host for this leech. This report is the first case of human infestation by the glossiphoniid leech.

Koriyama M.,Saga University | Hayami Y.,Saga University | Koga A.,Marine Biological Research Institute of Japan Co. | Yamamoto K.,Yamaguchi University | And 5 more authors.
Environmental Monitoring and Assessment | Year: 2013

To investigate seasonal variations of nutrient distribution in the mudflat-shallow water system, we conducted field surveys once a month from August 2007 to July 2008 in the inner area of Ariake Bay (IAB), Japan. The NH4 +-N concentration of the water column increased in autumn because of the high NH4 + release from the sediments, ranging from 850 to 3,001 μmol m-2 day-1. The NO3 --N concentration was maximal in January, which was thought to be caused by NO3 - release from the oxic sediments and by NO3 - regeneration due to water column nitrification. The PO4 3--P concentration of the water column was high in summer-autumn due to the high PO4 3- release from the reduced sediments, ranging from 22 to 164 μmol m -2 day-1. We estimated the total amounts of DIN and PO4 3--P release (R DIN and {R-{{\mathrm{P}{{\mathrm{O}}-4}}}} , respectively) from the muddy sediment area of the IAB. In summer-autumn, R DIN and {R-{{\mathrm{P}{{\mathrm{O}}- 4}}}} corresponded to about 47.7 % of DIN input and about 116.6 % of PO 4 3--P input from the river, respectively. Thus, we concluded that the muddy sediments were an important source of nutrients for the water column of the IAB during summer-autumn. In addition, we found that phosphorus necessary for the growth of Porphyra (Porphyra yezoensis, Rhodophyceae) would be insufficient in the water column when phosphorus during the Porphyra aquaculture period is supplied only from the river. Therefore, the phosphorus release from the muddy sediments was thought to play an important role in the sustainable production of Porphyra in Ariake Bay. © 2013 Springer Science+Business Media Dordrecht.

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