DSpace Collection: 2011-06-20
http://hdl.handle.net/2115/47529
2011-06-202024-03-29T12:31:34Z腐植物質が有害ラフィド藻Chattonella antiqua の増殖に与える影響
http://hdl.handle.net/2115/47537
Title: 腐植物質が有害ラフィド藻Chattonella antiqua の増殖に与える影響
Authors: 福﨑, 康司; 内藤, 佳奈子; 吉岡, 崇仁; 澤山, 茂樹; 今井, 一郎
Abstract: Humic subsatnces (HS) are major components of dissolved organic matter in aquatic systems and known to have a substantial influence on the trace metal speciation, and thus the bioavailability of trace elements. Trace metals, such as iron, frequently act as a crucial limiting factor for phytoplankton growth, and sometimes bloom developments in the sea. The effects of HS on the growth of the harmful red tide phytoplankton, Chattonella antiqua were investigated by using of a chemically defined artificial medium. Humic acid (0.6, 6, 60 and 600 μg L-1) supplied with iron (541 μg L-1 of ferric chloride hexahydrate) had accelerative effects on the growth of C. antiqua. The growth yield was highest in the medium of 6 μg L-1 of humic acid, and 8 times larger than that in the control medium without humic acid. On the contrary, fulvic acid did not enhance the growth of C. antiqua. It is suggested that the composition and concentration of HS possibly affects the bloom developments of C. antiqua by controlling the iron availability. This is the first report of the effects of humic substances on the growth of C. antiqua, raising an insight into the growth physiology of this fish-killing species.2011-06-19T15:00:00Z福﨑, 康司内藤, 佳奈子吉岡, 崇仁澤山, 茂樹今井, 一郎 Humic subsatnces (HS) are major components of dissolved organic matter in aquatic systems and known to have a substantial influence on the trace metal speciation, and thus the bioavailability of trace elements. Trace metals, such as iron, frequently act as a crucial limiting factor for phytoplankton growth, and sometimes bloom developments in the sea. The effects of HS on the growth of the harmful red tide phytoplankton, Chattonella antiqua were investigated by using of a chemically defined artificial medium. Humic acid (0.6, 6, 60 and 600 μg L-1) supplied with iron (541 μg L-1 of ferric chloride hexahydrate) had accelerative effects on the growth of C. antiqua. The growth yield was highest in the medium of 6 μg L-1 of humic acid, and 8 times larger than that in the control medium without humic acid. On the contrary, fulvic acid did not enhance the growth of C. antiqua. It is suggested that the composition and concentration of HS possibly affects the bloom developments of C. antiqua by controlling the iron availability. This is the first report of the effects of humic substances on the growth of C. antiqua, raising an insight into the growth physiology of this fish-killing species.Phenology in large grazing copepods in the Oyashio region, western subarctic Pacific
http://hdl.handle.net/2115/47536
Title: Phenology in large grazing copepods in the Oyashio region, western subarctic Pacific
Authors: Yamaguchi, Atsushi; Ohgi, Kohei; Kobari, Toru; Padmavati, Gadi; Ikeda, Tsutomu
Abstract: Seasonal sequence of population structure (=copepodid stage composition) of large grazing copepods (Metridia pacifica, Eucalanus bungii and Neocalanus spp.) was analyzed based on seasonal samples collected with 100 μm mesh nets from 0-500 m stratum at Site H in the Oyashio region, western subarctic Pacific, during 1996-1997 and 2002-2007. On the premise that there are little year-to-year differences, the composite data were arranged to the date of samplings of each year to yield seasonal developmental patterns of each copepod. Seasonal developmental pattern estimated by tracing the sequence of mean copepodid stages of the population at each sampling date revealed that the recruitment season of the population was January for N. cristatus, March for N. flemingeri and May for N. plumchrus and E. bungii. In contrast to these copepods with single recruitment seasons in the year, M. pacifica exhibited two recruitment seasons (mid-May and August) in a year. Phenology in reproduction and development of these copepods reflects their species-specific differences in energy utilization pattern ; M. pacifica and E. bungii spawn in phytoplankton-rich surface layer in spring (females need to feed for spawning) while Neocalanus spp. spawn in deep layer in winter (females do not feed). Development from C1 to C5 of N. cristatus, N. flemingeri and N. plumchrus was in January to June, March to June and May to August, respectively, thus the three sympatric Neocalanus spp. showed a clear temporal separation in the developmental timing in the western subarctic Pacific. This temporal separation in utilizing the surface layer is considered to be a mechanism to reduce inter-specific food competition. Regional comparison of phenology in copepods within the entire subarctic Pacific and its adjacent waters revealed that reproduction timing of the surface spawning M. pacifica and E. bungii was highly variable, while this was not the case for deep spawning Neocalanus spp.2011-06-19T15:00:00ZYamaguchi, AtsushiOhgi, KoheiKobari, ToruPadmavati, GadiIkeda, Tsutomu Seasonal sequence of population structure (=copepodid stage composition) of large grazing copepods (Metridia pacifica, Eucalanus bungii and Neocalanus spp.) was analyzed based on seasonal samples collected with 100 μm mesh nets from 0-500 m stratum at Site H in the Oyashio region, western subarctic Pacific, during 1996-1997 and 2002-2007. On the premise that there are little year-to-year differences, the composite data were arranged to the date of samplings of each year to yield seasonal developmental patterns of each copepod. Seasonal developmental pattern estimated by tracing the sequence of mean copepodid stages of the population at each sampling date revealed that the recruitment season of the population was January for N. cristatus, March for N. flemingeri and May for N. plumchrus and E. bungii. In contrast to these copepods with single recruitment seasons in the year, M. pacifica exhibited two recruitment seasons (mid-May and August) in a year. Phenology in reproduction and development of these copepods reflects their species-specific differences in energy utilization pattern ; M. pacifica and E. bungii spawn in phytoplankton-rich surface layer in spring (females need to feed for spawning) while Neocalanus spp. spawn in deep layer in winter (females do not feed). Development from C1 to C5 of N. cristatus, N. flemingeri and N. plumchrus was in January to June, March to June and May to August, respectively, thus the three sympatric Neocalanus spp. showed a clear temporal separation in the developmental timing in the western subarctic Pacific. This temporal separation in utilizing the surface layer is considered to be a mechanism to reduce inter-specific food competition. Regional comparison of phenology in copepods within the entire subarctic Pacific and its adjacent waters revealed that reproduction timing of the surface spawning M. pacifica and E. bungii was highly variable, while this was not the case for deep spawning Neocalanus spp.Evaluation of major nutrients regulating the growth of diatoms in Harima-Nada, the Seto Inland Sea, Japan
http://hdl.handle.net/2115/47535
Title: Evaluation of major nutrients regulating the growth of diatoms in Harima-Nada, the Seto Inland Sea, Japan
Authors: Naito, Kanako; Tanabe, Ayako; Itakura, Shigeru; Yamaguchi, Mineo; Imai, Ichiro
Abstract: In the eastern Seto Inland Sea, dissolved inorganic nitrogen has decreased due to the reduction of nutrient inputs, and there have been changes in the total cell density and the composition of the phytoplankton assemblages. The major phytoplankton component was diatoms, and the contribution was always over 90 percent of total phytoplankton since the 1990s. In order to elucidate growth characteristics and nutrient consumption of diatom species, we conducted major nutrients-enrichment bottle incubation experiments on shipboard using the surface waters in Harima-Nada, eastern part of the Seto Inland Sea. Seawater incubation experiments demonstrated that nutrient environments for phytoplankton are in a state of nitrogen-limitation in Harima-Nada. The addition of nitrate to surface waters of this coastal region promotes blooms of large chain-forming diatom species. These results suggest that diatom blooms cause depletion of the nutrients (mainly nitrogen) in Harima-Nada.2011-06-19T15:00:00ZNaito, KanakoTanabe, AyakoItakura, ShigeruYamaguchi, MineoImai, Ichiro In the eastern Seto Inland Sea, dissolved inorganic nitrogen has decreased due to the reduction of nutrient inputs, and there have been changes in the total cell density and the composition of the phytoplankton assemblages. The major phytoplankton component was diatoms, and the contribution was always over 90 percent of total phytoplankton since the 1990s. In order to elucidate growth characteristics and nutrient consumption of diatom species, we conducted major nutrients-enrichment bottle incubation experiments on shipboard using the surface waters in Harima-Nada, eastern part of the Seto Inland Sea. Seawater incubation experiments demonstrated that nutrient environments for phytoplankton are in a state of nitrogen-limitation in Harima-Nada. The addition of nitrate to surface waters of this coastal region promotes blooms of large chain-forming diatom species. These results suggest that diatom blooms cause depletion of the nutrients (mainly nitrogen) in Harima-Nada.北海道南部の北斗市沖から採集された雌雄同体のトラフグTakifugu rubripes
http://hdl.handle.net/2115/47534
Title: 北海道南部の北斗市沖から採集された雌雄同体のトラフグTakifugu rubripes
Authors: 河合, 俊郎; 松原, 創
Abstract: A single specimen of a hermaphroditic tiger puffer, Takifugu rubripes (Temminck and Schlegel, 1850), was collected from the western North Pacific, off Hokuto, Hokkaido, Japan. The left gonad of the specimen was of testicular tissue, and the right gonad was ovarian tissue sandwiched by testicular tissue. This is the first instance of hermaphrodism in this species. In addition, the anterior and posterior nostrils of the specimen were fused to each other, and the left side of the body was abnormally pigmented.2011-06-19T15:00:00Z河合, 俊郎松原, 創 A single specimen of a hermaphroditic tiger puffer, Takifugu rubripes (Temminck and Schlegel, 1850), was collected from the western North Pacific, off Hokuto, Hokkaido, Japan. The left gonad of the specimen was of testicular tissue, and the right gonad was ovarian tissue sandwiched by testicular tissue. This is the first instance of hermaphrodism in this species. In addition, the anterior and posterior nostrils of the specimen were fused to each other, and the left side of the body was abnormally pigmented.