Bio: 光雄 千原 is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 148 citations.
01 Jan 1997
TL;DR: The results from both laboratory-rearing experiments and field investiga- tions were combined to construct the seasonal life cycle and geographical distribution of N. nomurai in eastern Asian waters.
Abstract: A population explosion of the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizo- stomeae) occurred in the Sea of Japan in 2002 and 2003, causing severe damage to fisheries. There was a further population explosion in 2004, but on a much smaller scale. In both years, young medusae began to appear in the Tsushima and Korea Strait in July and August, followed by a north- ward expatriation in the Tsushima Current to the northern Sea of Japan. We obtained scyphistomae of this species by artificial fertilization, and reared them to the young medusa stage in the laboratory. Asexual reproduction of scyphistomae occurred by means of podocyst formation. A thermal increase from 13 to 23°C induced strobilation, followed by liberation of 3 to 7 ephyrae from a strobila. The ephyrae developed to metephyrae having a complex canal system and characteristically possessing long reddish purple filiform appendages. By 40 d post-liberation, the metephyrae had grown to medusae in which the central mouth had closed and been replaced by numerous mouthlets on both oral wings and scapulets. The results from both laboratory-rearing experiments and field investiga- tions were combined to construct the seasonal life cycle and geographical distribution of N. nomurai in eastern Asian waters. Possible causes for the mass occurrence of N. nomurai, which has tended to be more frequent in the last decade, are discussed.
TL;DR: In this article, the authors detected phenological and quantitative changes in the copepod community in response to the decadal climatic variation in the western subarctic North Pacific by analyzing the extensive zooplankton collection taken since the 1950s.
Abstract: Decadal- to multi-decadal variations have been reported in many regional ecosystems in the North Pacific, resulting in an increasing demand to elucidate the link between long-term climatic forcing and marine ecosystems We detected phenological and quantitative changes in the copepod community in response to the decadal climatic variation in the western subarctic North Pacific by analyzing the extensive zooplankton collection taken since the 1950s, the Odate Collection Copepod species were classified into five seasonal groups depending on the timing of the annual peak in abundance The abundance of the spring community gradually increased for the period 1960–2002 The spring–summer community also showed an increasing trend in May, but a decadal oscillation pattern of quasi-30-year cycles in July Phenological changes coincided with the climate regime shift in the mid-1970s, indicated by the Pacific decadal oscillation index (PDO) After the regime shift, the timing of the peak abundance was delayed one month, from March–April to April–May, in the spring community, whereas it peaked earlier, from June–July to May–June, in the spring–summer community, resulting in an overlap of the high productivity period for the two communities in May Wintertime cooling, followed by rapid summertime warming, was considered to be responsible for delayed initiation and early termination of the productive season after the mid-1970s Another phenological shift, quite different from the previous decade, was observed in the mid-1990s, when warm winters followed by cool summers lengthened the productive season The results suggest that climatic forcing with different decadal cycles may operate independently during winter–spring and spring–summer to create seasonal and interannual variations in hydrographic conditions; thus, combinations of these seasonal processes may determine the annual biological productivity
TL;DR: It is revealed that violaxanthin of C. ellipsoidea holds promise for use as a potential anti-inflammatory agent for either therapeutic or functional adjuvant purposes.
Abstract: Violaxanthin is a major carotenoid of microalgae Chlorella ellipsoidea and is also found in dark-green leafy vegetables, such as spinach. In this study, the anti-inflammatory effect of violaxanthin isolated from C. ellipsoidea was examined using lipopolysaccharide (LPS)-stimulated RAW 264.7 mouse macrophage cells. In addition, the anti-inflammatory activity and mechanism of action of purified violaxanthin was assessed using various assays, such as quantitative real-time polymerase chain reaction (PCR), Western blotting, and electrophoretic-mobility shift assay (EMSA). The results of this combined analysis revealed that violaxanthin significantly inhibited nitric oxide (NO) and the prostaglandin E₂ (PGE₂). Interestingly, violaxanthin effectively inhibited LPS-mediated nuclear factor-κB (NF-κB) p65 subunit translocation into the nucleus, suggesting that the violaxanthin anti-inflammatory activity may be based on inhibition of the NF-κB pathways. In conclusion, violaxanthin of C. ellipsoidea holds promise for use as a potential anti-inflammatory agent for either therapeutic or functional adjuvant purposes.
TL;DR: This is the first attempt to estimate species richness for all marine species in Japanese waters, and indicates that more than 70% of Japan's marine biodiversity remains un-described.
Abstract: To understand marine biodiversity in Japanese waters, we have compiled information on the marine biota in Japanese waters, including the number of described species (species richness), the history of marine biology research in Japan, the state of knowledge, the number of endemic species, the number of identified but undescribed species, the number of known introduced species, and the number of taxonomic experts and identification guides, with consideration of the general ocean environmental background, such as the physical and geological settings. A total of 33,629 species have been reported to occur in Japanese waters. The state of knowledge was extremely variable, with taxa containing many inconspicuous, smaller species tending to be less well known. The total number of identified but undescribed species was at least 121,913. The total number of described species combined with the number of identified but undescribed species reached 155,542. This is the best estimate of the total number of species in Japanese waters and indicates that more than 70% of Japan's marine biodiversity remains un-described. The number of species reported as introduced into Japanese waters was 39. This is the first attempt to estimate species richness for all marine species in Japanese waters. Although its marine biota can be considered relatively well known, at least within the Asian-Pacific region, considering the vast number of different marine environments such as coral reefs, ocean trenches, ice-bound waters, methane seeps, and hydrothermal vents, much work remains to be done. We expect global change to have a tremendous impact on marine biodiversity and ecosystems. Japan is in a particularly suitable geographic situation and has a lot of facilities for conducting marine science research. Japan has an important responsibility to contribute to our understanding of life in the oceans.
TL;DR: In this paper, the influence of the northeast (NE) and the southwest (SW) monsoons on copepod assemblages in the Danshuei River in the northwestern tip of Taiwan was assessed.
Abstract: Danshuei River in the northwestern tip of Taiwan discharges into the boundary coastal waters between the East China Sea and the Taiwan Strait. We conducted a 5-year study between October 1998 and September 2003 to assess the influence of the northeast (NE) and the southwest (SW) monsoons on copepod assemblages in the area. A total of 110 copepod species were identified. Temora turbinata, Paracalanus aculeatus, Acrocalanus gibber, Parvocalanus crassirostris and Oithona rigida comprised 80% of the copepod assemblages that consisted of coastal species from the East China Sea and species associated with the Kuroshio Branch Current. The effect of the NE monsoon was observed during a short period of each winter when species such as Calanus sinicus were transported into the study area by the China Coastal Current. In summer, species such as A. gibber, Acrocalanus gracilis and Canthocalanus pauper may be transported into the study area from Southern Taiwan by the combined effect of the SW monsoon and the Kuroshio Current. Influence of the NE monsoon on the copepod assemblages in terms of introduction of species from the Yellow Sea and the East China Sea during winter was observed every year but was unlikely to represent an important carbon source into the region due to its short-term nature. Local species such as T. turbinata, P. crassirostris and O. rigida form a major component of the copepod assemblage. The high copepod diversity in the area was caused by the year-round presence of many local species and the aggregation of different species from subtropical, tropical, and temperate water masses. Monsoon-driven water currents and the Kuroshio Branch Current appeared to mask the effect of river discharge in the region.