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Tomohiko Kikuchi - One of the best experts on this subject based on the ideXlab platform.
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of vertical migration and cell division
Harmful Algae, 2009Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Kyoungsoon Shin, Tomohiko KikuchiAbstract:Abstract To better understand the mechanism underlying the bloom outbreaks of dinoflagellates, Ceratium furca , and Ceratium fusus in the temperate coastal area of Sagami Bay, we investigated the diel changes of vertical migration, swimming speed, cell volume, and cell division. Our results from both the field and laboratory indicate that C. furca and C. fusus can migrate vertically between surface and sub-surface layers to avoid strong sunlight (>1000 μmol m −2 s −1 ). Diel vertical migration (DVM) of C. furca was observed in the laboratory, while that of C. fusus was not observed. C. furca demonstrated a constant DVM rhythm, i.e., their cells began to descend from the surface before the light was extinguished, and ascended into the surface before the light was turned on. The downward and upward migrations of the cells occurred at every 3 h before turning on and off the light, suggesting that the DVM pattern was independent of nutrient concentration. The swimming speeds of C. furca (avg. 250 μm s −1 ) were always faster than those of C. fusus (avg. 75 μm s −1 ). In addition, the speeds of C. furca during light periods were faster than those during dark periods, whereas the speeds of C. fusus remained relatively constant. A higher proportion of dividing cells was recorded near dawn (05:00–07:00 h). Cell volumes of C. furca and C. fusus did not markedly change between 12:00 and 21:00 h, but gradually increased until 03:00 h and then sharply decreased. Furthermore, the cell volume of the two Ceratium species was significantly shifted to the temporal pattern of cell division. Combined with the DVM manner of two Ceratium and cell division timing, only C. furca divided at the bottom, and then moved toward the surface shortly before the dark to light transition. Based on our observations, C. furca has an ecological advantage due to their DVM activity, since nutrients can be obtained well in the near bottom layers, while during the daytime, light present in nutrient-depleted surface water can be obtained using their high swimming speed. On the other hand, C. fusus stimulated by low salinity conditions, might be dependent on external environmental conditions such as additional nutrients following freshwater discharge by heavy rainfall because they may not perform active DVM due to a slow swimming ability. Our findings support that specific characteristics, including the DVM behavior in C. furca , yield a competitive advantage over C. fusus in Sagami Bay.
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of nutrients
Harmful Algae, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Tomohiko KikuchiAbstract:Abstract In order to study the influence of nutrients on the growth characteristics of the dominant dinoflagellates, Ceratium furca and Ceratium fusus , in the temperate coastal area of Sagami Bay, Japan, we conducted field monitoring from January 2000 to December 2005 and performed laboratory culture experiments. In the field study, population densities of C. furca and C. fusus were high, even in low nutrient concentrations (N: 1.58 μM, P: 0.17 μM). Both species were more abundant in the surface and sub-surface layers than in the bottom layers during the stratification periods. In the laboratory study, the specific growth rates of C. furca and C. fusus increased gradually along with increasing nutrients up to the T 5 (N: 5 μM, P: 0.5 μM) and T 10 (N: 10 μM, P: 1 μM) concentration levels, after which the growth rate plateaued at the T 50 (N: 50 μM, P: 5 μM) concentration level. In contrast, the nutrient uptake rates of both species continuously increased, indicating “luxury consumption”, i.e., excessive cellular storage not related to growth rate. The half-saturation constants ( K s ) of C. furca for nitrate (0.49 μM) and phosphate (0.05 μM) were slightly higher than C. fusus (0.32 and 0.03 μM, respectively). We offer two reasons why the two Ceratium population densities were maintained at high levels in low nutrient conditions. First, these two species have a competitive advantage over other algal species because of low K s values and specific characteristics for nutrient uptake such as luxury consumption. Their ability to obtain nutrients through alternative methods, such as phagotrophy, might contribute to bloom formation and population persistence. Second, the cell densities of both Ceratium species increased along with nitrate concentrations in the media even when phosphorus was held constant. In particular, the growth of C. furca was directly supported by various nitrogen sources such as nitrate, ammonium, and urea, although the highest growth rates were observed only in the nitrate-enriched cultures. Our field and laboratory results revealed that the growth rates of the two Ceratium species increased readily in high N:P nutrient conditions (i.e., conditions of P limitation) indicating an advantage over other algal species in phosphorus-limited environments such as Sagami Bay.
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population development of the dinoflagellates Ceratium furca and Ceratium fusus during spring and early summer in iwa harbor sagami bay japan
Ocean Science Journal, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Tomohiko KikuchiAbstract:To examine the population development of the dinoflagellates, Ceratium furca and Ceratium fusus, daily field monitoring was conducted between April and July 2003 in the temperate coastal water of Sagami Bay, Japan. During the study period, the concentrations of C. furca were always lower than those of C. fusus. A sharp increase in the densities of both species was recorded on 5 May showing the maximum cell concentrations (C. furca = 14,800 cells L-1, C. fusus = 49,600 cells L-1). In the 7 days prior to the May bloom of the Ceratium species (29 April to 1 May), the highest density of the heterotrophic dinoflagellate Noctiluca scintillans was observed. Additionally, a second bloom of C. fusus occurred on 22 July. Here, two causes of the significant increases in the Ceratium populations during the two blooming periods (first time; 1 to 8 May, second time; 15 to 22 July) are presented. First, an increase in the nutrients of the surface layer regenerated by the breakdown of blooms by N.scintillans could be considered as a major cause of the population increase of the two Ceratium species. Second, a decrease in salinity (to 27 psu) was correlated with the later bloom ofC. fusus. These results suggest that the population development of the two Ceratium species requires nutrients regenerated after the reduction of the diatom population byN. scintillans and, forC. fusus, continuous low salinity conditions, compared to other environmental factors during the rainy season. Key words: Ceratium furca; Ceratium fusus; Noctiluca scintillans; Bloom process; Environmental factor
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of temperature light intensity and photoperiod
Harmful Algae, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Tomohiko KikuchiAbstract:Abstract Seasonal changes of field populations and growth rates of two dinoflagellates, Ceratium furca and Ceratium fusus, were examined in the temperate coastal water of Sagami Bay, Japan. Weekly field sampling was conducted from August 2002 to August 2003, and laboratory experiments were also carried out to investigate effects of temperature, irradiance and photoperiod on the growth rates of these two Ceratium species. In the field, the abundances of both species increased significantly from April to August 2003, were gradually decreased from November 2002 and were not observed in January 2003. C. fusus was able to increase at lower temperatures in February 2003 compared to C. furca. In the laboratory, the two species did not grow at 32 °C. The highest specific growth rate of C. furca was 0.72 d−1 at 24 °C and 600 μmol m−2 s−1. Optimum growth rates (>0.4 d−1) of C. furca were observed at temperatures from 18 to 28 °C and at irradiances from 216 to 796 μmol m−2 s−1. The highest growth rate of C. fusus was 0.56 d−1 at 26 °C and 216 μmol m−2 s−1. Optimum growth rates of C. fusus were observed at the same irradiance rage of C. furca, whereas optimum temperature range was narrower (26–28 °C). The growth curves of both species indicated saturation of the growth rates when light intensity was above 216 μmol m−2 s−1, and did not show photoinhibition at irradiances up to 796 μmol m−2 s−1. The specific growth rates of both Ceratium species were clearly decreased at L:D = 10:14 relative to those at L:D = 14:10 and L:D = 12:12. The present study indicates the two Ceratium species can adapt to a wide range of temperature and irradiance.
Seung Ho Baek - One of the best experts on this subject based on the ideXlab platform.
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ecological behavior of the dinoflagellate Ceratium furca in jangmok harbor of jinhae bay korea
Journal of Plankton Research, 2011Co-Authors: Seung Ho Baek, Shinji Shimode, Hyeon Ho Shin, Hyunwoo Choi, Ok Myung Hwang, Kyoungsoon Shin, Youngok KimAbstract:The rhythmic migration pattern of the dinoflagellate Ceratium furca is a result of ecological adaptation to avoid high irradiance. The high proportions of dividing cells at deeper depths are likely to be an ecological response to maintain their population away from the turbulence in the near-surface layer.
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of vertical migration and cell division
Harmful Algae, 2009Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Kyoungsoon Shin, Tomohiko KikuchiAbstract:Abstract To better understand the mechanism underlying the bloom outbreaks of dinoflagellates, Ceratium furca , and Ceratium fusus in the temperate coastal area of Sagami Bay, we investigated the diel changes of vertical migration, swimming speed, cell volume, and cell division. Our results from both the field and laboratory indicate that C. furca and C. fusus can migrate vertically between surface and sub-surface layers to avoid strong sunlight (>1000 μmol m −2 s −1 ). Diel vertical migration (DVM) of C. furca was observed in the laboratory, while that of C. fusus was not observed. C. furca demonstrated a constant DVM rhythm, i.e., their cells began to descend from the surface before the light was extinguished, and ascended into the surface before the light was turned on. The downward and upward migrations of the cells occurred at every 3 h before turning on and off the light, suggesting that the DVM pattern was independent of nutrient concentration. The swimming speeds of C. furca (avg. 250 μm s −1 ) were always faster than those of C. fusus (avg. 75 μm s −1 ). In addition, the speeds of C. furca during light periods were faster than those during dark periods, whereas the speeds of C. fusus remained relatively constant. A higher proportion of dividing cells was recorded near dawn (05:00–07:00 h). Cell volumes of C. furca and C. fusus did not markedly change between 12:00 and 21:00 h, but gradually increased until 03:00 h and then sharply decreased. Furthermore, the cell volume of the two Ceratium species was significantly shifted to the temporal pattern of cell division. Combined with the DVM manner of two Ceratium and cell division timing, only C. furca divided at the bottom, and then moved toward the surface shortly before the dark to light transition. Based on our observations, C. furca has an ecological advantage due to their DVM activity, since nutrients can be obtained well in the near bottom layers, while during the daytime, light present in nutrient-depleted surface water can be obtained using their high swimming speed. On the other hand, C. fusus stimulated by low salinity conditions, might be dependent on external environmental conditions such as additional nutrients following freshwater discharge by heavy rainfall because they may not perform active DVM due to a slow swimming ability. Our findings support that specific characteristics, including the DVM behavior in C. furca , yield a competitive advantage over C. fusus in Sagami Bay.
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of nutrients
Harmful Algae, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Tomohiko KikuchiAbstract:Abstract In order to study the influence of nutrients on the growth characteristics of the dominant dinoflagellates, Ceratium furca and Ceratium fusus , in the temperate coastal area of Sagami Bay, Japan, we conducted field monitoring from January 2000 to December 2005 and performed laboratory culture experiments. In the field study, population densities of C. furca and C. fusus were high, even in low nutrient concentrations (N: 1.58 μM, P: 0.17 μM). Both species were more abundant in the surface and sub-surface layers than in the bottom layers during the stratification periods. In the laboratory study, the specific growth rates of C. furca and C. fusus increased gradually along with increasing nutrients up to the T 5 (N: 5 μM, P: 0.5 μM) and T 10 (N: 10 μM, P: 1 μM) concentration levels, after which the growth rate plateaued at the T 50 (N: 50 μM, P: 5 μM) concentration level. In contrast, the nutrient uptake rates of both species continuously increased, indicating “luxury consumption”, i.e., excessive cellular storage not related to growth rate. The half-saturation constants ( K s ) of C. furca for nitrate (0.49 μM) and phosphate (0.05 μM) were slightly higher than C. fusus (0.32 and 0.03 μM, respectively). We offer two reasons why the two Ceratium population densities were maintained at high levels in low nutrient conditions. First, these two species have a competitive advantage over other algal species because of low K s values and specific characteristics for nutrient uptake such as luxury consumption. Their ability to obtain nutrients through alternative methods, such as phagotrophy, might contribute to bloom formation and population persistence. Second, the cell densities of both Ceratium species increased along with nitrate concentrations in the media even when phosphorus was held constant. In particular, the growth of C. furca was directly supported by various nitrogen sources such as nitrate, ammonium, and urea, although the highest growth rates were observed only in the nitrate-enriched cultures. Our field and laboratory results revealed that the growth rates of the two Ceratium species increased readily in high N:P nutrient conditions (i.e., conditions of P limitation) indicating an advantage over other algal species in phosphorus-limited environments such as Sagami Bay.
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population development of the dinoflagellates Ceratium furca and Ceratium fusus during spring and early summer in iwa harbor sagami bay japan
Ocean Science Journal, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Tomohiko KikuchiAbstract:To examine the population development of the dinoflagellates, Ceratium furca and Ceratium fusus, daily field monitoring was conducted between April and July 2003 in the temperate coastal water of Sagami Bay, Japan. During the study period, the concentrations of C. furca were always lower than those of C. fusus. A sharp increase in the densities of both species was recorded on 5 May showing the maximum cell concentrations (C. furca = 14,800 cells L-1, C. fusus = 49,600 cells L-1). In the 7 days prior to the May bloom of the Ceratium species (29 April to 1 May), the highest density of the heterotrophic dinoflagellate Noctiluca scintillans was observed. Additionally, a second bloom of C. fusus occurred on 22 July. Here, two causes of the significant increases in the Ceratium populations during the two blooming periods (first time; 1 to 8 May, second time; 15 to 22 July) are presented. First, an increase in the nutrients of the surface layer regenerated by the breakdown of blooms by N.scintillans could be considered as a major cause of the population increase of the two Ceratium species. Second, a decrease in salinity (to 27 psu) was correlated with the later bloom ofC. fusus. These results suggest that the population development of the two Ceratium species requires nutrients regenerated after the reduction of the diatom population byN. scintillans and, forC. fusus, continuous low salinity conditions, compared to other environmental factors during the rainy season. Key words: Ceratium furca; Ceratium fusus; Noctiluca scintillans; Bloom process; Environmental factor
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of temperature light intensity and photoperiod
Harmful Algae, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Tomohiko KikuchiAbstract:Abstract Seasonal changes of field populations and growth rates of two dinoflagellates, Ceratium furca and Ceratium fusus, were examined in the temperate coastal water of Sagami Bay, Japan. Weekly field sampling was conducted from August 2002 to August 2003, and laboratory experiments were also carried out to investigate effects of temperature, irradiance and photoperiod on the growth rates of these two Ceratium species. In the field, the abundances of both species increased significantly from April to August 2003, were gradually decreased from November 2002 and were not observed in January 2003. C. fusus was able to increase at lower temperatures in February 2003 compared to C. furca. In the laboratory, the two species did not grow at 32 °C. The highest specific growth rate of C. furca was 0.72 d−1 at 24 °C and 600 μmol m−2 s−1. Optimum growth rates (>0.4 d−1) of C. furca were observed at temperatures from 18 to 28 °C and at irradiances from 216 to 796 μmol m−2 s−1. The highest growth rate of C. fusus was 0.56 d−1 at 26 °C and 216 μmol m−2 s−1. Optimum growth rates of C. fusus were observed at the same irradiance rage of C. furca, whereas optimum temperature range was narrower (26–28 °C). The growth curves of both species indicated saturation of the growth rates when light intensity was above 216 μmol m−2 s−1, and did not show photoinhibition at irradiances up to 796 μmol m−2 s−1. The specific growth rates of both Ceratium species were clearly decreased at L:D = 10:14 relative to those at L:D = 14:10 and L:D = 12:12. The present study indicates the two Ceratium species can adapt to a wide range of temperature and irradiance.
Fernando Gómez - One of the best experts on this subject based on the ideXlab platform.
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REINSTATEMENT OF THE DINOFLAGELLATE GENUS Tripos TO REPLACE NeoCeratium , MARINE SPECIES OF Ceratium (DINOPHYCEAE, ALVEOLATA)
CICIMAR Oceánides, 2013Co-Authors: Fernando GómezAbstract:Morphological and molecular data support the split at the genus level of the marine and freshwater species of the dinoflagellate Ceratium (Gonyaulacales, Dinophyceae). A new genus name NeoCeratium F. Gomez, D. Moreira & P. Lopez-Garcia was proposed for the marine species. However, it is considered illegitimate (type species is type of BiCeratium Vanhoffen), and the nomenclatural priority is here given for the genus Tripos Bory (type species Tripos muelleri ) which replaces NeoCeratium . New combinations are proposed for the existing names of species and infraspecific taxa. Reinstalacion del genero de dinoflagelados Tripos para reemplazar a NeoCeratium , especies marinas de Ceratium (Dinophyceae, Alveolata) Las evidencias morfologicas y moleculares apoyan la separacion a nivel de genero de las especies marinas y dulceacuicolas del dinoflagelado Ceratium (Gonyaulacales, Dinophyceae). Asi, el nuevo nombre generico NeoCeratium F. Gomez, D. Moreira & P. Lopez-Garcia se propuso para las especies marinas. Sin embargo, ha sido considerado ilegitimo (la especie tipo es el tipo de BiCeratium Vanhoffen) y la prioridad en nomenclatura se otorga al genero Tripos Bory. El genero Tripos con la especie tipo Tripos muelleri remplaza a NeoCeratium . Se proponen nuevas combinaciones para los nombres existentes de especies y taxones infraespecificos.
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NeoCeratium gen. nov., a new genus for all marine species currently assigned to Ceratium (Dinophyceae).
Protist, 2010Co-Authors: Fernando Gómez, David Moreira, Purificación López-garcíaAbstract:The dinoflagellate genus Ceratium contains marine and freshwater species. Freshwater species possess six cingular plates, thick plates in the concave ventral area and usually develop a third hypothecal horn. The marine Ceratium species (>62 species) possess five cingular plates and thin plates in the concave ventral area; a third hypothecal horn is atypical. Resting cysts, a common feature in the freshwater species, are unreported in marine species. We illustrate for the first time resting cysts in marine Ceratium species (C. furca and C. candelabrum). We obtained small subunit ribosomal RNA gene (SSU rDNA) sequences of 23 Ceratium species (more than one third of the total marine species described so far), with representatives of the four acknowledged subgenera. Phylogenetic analyses including the type species, the freshwater C. hirundinella, showed that the four available sequences of freshwater species formed a strongly supported subclade, very distant from the marine cluster. Our data support the splitting of Ceratium sensu lato into two genera. Ceratium sensu stricto should be reserved for freshwater species possessing six cingular plates (three cingular plates in dorsal view). The new genus name, NeoCeratium gen. nov. should be applied to the marine species of Ceratium sensu lato that possess five cingular plates (two cingular plates in dorsal view).
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rarely reported dinoflagellates of the genera Ceratium gloeodinium histioneis oxytoxum and prorocentrum dinophyceae from the open southeast pacific ocean
Revista De Biologia Marina Y Oceanografia, 2008Co-Authors: Fernando Gómez, Herve Claustre, Sami SouissiAbstract:Se ilustran y brevemente describen dinoflagelados raramente citados de los generos Ceratium, Gloeodinium, Histioneis, Oxytoxum y Prorocentrum procedentes de un transecto de ~8000 km entre el archipielago de las Islas Marquesas y las costas chilenas. Se han encontrado diecinueve especies del genero Oxytoxum y siete especies de Histioneis. Se proporcionan por primera vez microfotografias de Histioneis hyalina, H. cf. pulchra y un especimen identificado como Histiophysis sp., un genero que no habia sido citado desde su descripcion original. Mas alla de los tipicos especimenes unicelulares de Prorocentrum, se describe un comportamiento colonial en Prorocentrum dentatum que presentaba celulas alineadas. Colonias de pares de celulas elipsoidales o esfericas embebidas en una matriz hialina se han adscrito a Gloeodinium marinum. Ceratium lanceolatum se encuentra por primera vez en el Pacifico Sur desde su descripcion original. Se proporcionan microfotografias de Ceratium carnegiei, C. divaricatum y C. lanceolatum
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rarely reported dinoflagellates of the genera Ceratium gloeodinium histioneis oxytoxum and prorocentrum dinophyceae from the open southeast pacific ocean dinoflagelados raramente citados de los generos Ceratium gloeodinium histioneis oxytoxum y prorocentrum dinophyceae en aguas abiertas del pacifico sur oriental
2008Co-Authors: Fernando Gómez, Herve Claustre, Sami SouissiAbstract:Rarely reported dinoflagellates of the genera Ceratium, Gloeodinium, Histioneis, Oxytoxum and Prorocentrum from a ~8000 km transect between the Marquesas Islands Archipelago and the Chilean coast are briefly described and illustrated. Nineteen species of the genus Oxytoxum and seven species of the genus Histioneis were identified to species level. Photographic records of Histioneis hyalina and H. cf. pulchra are for the first time reported. One specimen ascribed to Histiophysis sp., a genus never reported since the first description, is illustrated. Beyond the single- cell specimens of Prorocentrum, a colonial behavior was observed. A small species, identified as Prorocentrum dentatum, was encountered forming rows. Colonies of pairs of ellipsoidal or sphaerical cells embedded in a hyaline matrix have been ascribed to Gloeodinium marinum. Ceratium lanceolatum is for the first time reported in the South Pacific Ocean since the first description. Photographic records of Ceratium carnegiei, C. divaricatum and C. lanceolatum are reported.
Shinji Shimode - One of the best experts on this subject based on the ideXlab platform.
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ecological behavior of the dinoflagellate Ceratium furca in jangmok harbor of jinhae bay korea
Journal of Plankton Research, 2011Co-Authors: Seung Ho Baek, Shinji Shimode, Hyeon Ho Shin, Hyunwoo Choi, Ok Myung Hwang, Kyoungsoon Shin, Youngok KimAbstract:The rhythmic migration pattern of the dinoflagellate Ceratium furca is a result of ecological adaptation to avoid high irradiance. The high proportions of dividing cells at deeper depths are likely to be an ecological response to maintain their population away from the turbulence in the near-surface layer.
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of vertical migration and cell division
Harmful Algae, 2009Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Kyoungsoon Shin, Tomohiko KikuchiAbstract:Abstract To better understand the mechanism underlying the bloom outbreaks of dinoflagellates, Ceratium furca , and Ceratium fusus in the temperate coastal area of Sagami Bay, we investigated the diel changes of vertical migration, swimming speed, cell volume, and cell division. Our results from both the field and laboratory indicate that C. furca and C. fusus can migrate vertically between surface and sub-surface layers to avoid strong sunlight (>1000 μmol m −2 s −1 ). Diel vertical migration (DVM) of C. furca was observed in the laboratory, while that of C. fusus was not observed. C. furca demonstrated a constant DVM rhythm, i.e., their cells began to descend from the surface before the light was extinguished, and ascended into the surface before the light was turned on. The downward and upward migrations of the cells occurred at every 3 h before turning on and off the light, suggesting that the DVM pattern was independent of nutrient concentration. The swimming speeds of C. furca (avg. 250 μm s −1 ) were always faster than those of C. fusus (avg. 75 μm s −1 ). In addition, the speeds of C. furca during light periods were faster than those during dark periods, whereas the speeds of C. fusus remained relatively constant. A higher proportion of dividing cells was recorded near dawn (05:00–07:00 h). Cell volumes of C. furca and C. fusus did not markedly change between 12:00 and 21:00 h, but gradually increased until 03:00 h and then sharply decreased. Furthermore, the cell volume of the two Ceratium species was significantly shifted to the temporal pattern of cell division. Combined with the DVM manner of two Ceratium and cell division timing, only C. furca divided at the bottom, and then moved toward the surface shortly before the dark to light transition. Based on our observations, C. furca has an ecological advantage due to their DVM activity, since nutrients can be obtained well in the near bottom layers, while during the daytime, light present in nutrient-depleted surface water can be obtained using their high swimming speed. On the other hand, C. fusus stimulated by low salinity conditions, might be dependent on external environmental conditions such as additional nutrients following freshwater discharge by heavy rainfall because they may not perform active DVM due to a slow swimming ability. Our findings support that specific characteristics, including the DVM behavior in C. furca , yield a competitive advantage over C. fusus in Sagami Bay.
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of nutrients
Harmful Algae, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Tomohiko KikuchiAbstract:Abstract In order to study the influence of nutrients on the growth characteristics of the dominant dinoflagellates, Ceratium furca and Ceratium fusus , in the temperate coastal area of Sagami Bay, Japan, we conducted field monitoring from January 2000 to December 2005 and performed laboratory culture experiments. In the field study, population densities of C. furca and C. fusus were high, even in low nutrient concentrations (N: 1.58 μM, P: 0.17 μM). Both species were more abundant in the surface and sub-surface layers than in the bottom layers during the stratification periods. In the laboratory study, the specific growth rates of C. furca and C. fusus increased gradually along with increasing nutrients up to the T 5 (N: 5 μM, P: 0.5 μM) and T 10 (N: 10 μM, P: 1 μM) concentration levels, after which the growth rate plateaued at the T 50 (N: 50 μM, P: 5 μM) concentration level. In contrast, the nutrient uptake rates of both species continuously increased, indicating “luxury consumption”, i.e., excessive cellular storage not related to growth rate. The half-saturation constants ( K s ) of C. furca for nitrate (0.49 μM) and phosphate (0.05 μM) were slightly higher than C. fusus (0.32 and 0.03 μM, respectively). We offer two reasons why the two Ceratium population densities were maintained at high levels in low nutrient conditions. First, these two species have a competitive advantage over other algal species because of low K s values and specific characteristics for nutrient uptake such as luxury consumption. Their ability to obtain nutrients through alternative methods, such as phagotrophy, might contribute to bloom formation and population persistence. Second, the cell densities of both Ceratium species increased along with nitrate concentrations in the media even when phosphorus was held constant. In particular, the growth of C. furca was directly supported by various nitrogen sources such as nitrate, ammonium, and urea, although the highest growth rates were observed only in the nitrate-enriched cultures. Our field and laboratory results revealed that the growth rates of the two Ceratium species increased readily in high N:P nutrient conditions (i.e., conditions of P limitation) indicating an advantage over other algal species in phosphorus-limited environments such as Sagami Bay.
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population development of the dinoflagellates Ceratium furca and Ceratium fusus during spring and early summer in iwa harbor sagami bay japan
Ocean Science Journal, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Myungsoo Han, Tomohiko KikuchiAbstract:To examine the population development of the dinoflagellates, Ceratium furca and Ceratium fusus, daily field monitoring was conducted between April and July 2003 in the temperate coastal water of Sagami Bay, Japan. During the study period, the concentrations of C. furca were always lower than those of C. fusus. A sharp increase in the densities of both species was recorded on 5 May showing the maximum cell concentrations (C. furca = 14,800 cells L-1, C. fusus = 49,600 cells L-1). In the 7 days prior to the May bloom of the Ceratium species (29 April to 1 May), the highest density of the heterotrophic dinoflagellate Noctiluca scintillans was observed. Additionally, a second bloom of C. fusus occurred on 22 July. Here, two causes of the significant increases in the Ceratium populations during the two blooming periods (first time; 1 to 8 May, second time; 15 to 22 July) are presented. First, an increase in the nutrients of the surface layer regenerated by the breakdown of blooms by N.scintillans could be considered as a major cause of the population increase of the two Ceratium species. Second, a decrease in salinity (to 27 psu) was correlated with the later bloom ofC. fusus. These results suggest that the population development of the two Ceratium species requires nutrients regenerated after the reduction of the diatom population byN. scintillans and, forC. fusus, continuous low salinity conditions, compared to other environmental factors during the rainy season. Key words: Ceratium furca; Ceratium fusus; Noctiluca scintillans; Bloom process; Environmental factor
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growth of dinoflagellates Ceratium furca and Ceratium fusus in sagami bay japan the role of temperature light intensity and photoperiod
Harmful Algae, 2008Co-Authors: Seung Ho Baek, Shinji Shimode, Tomohiko KikuchiAbstract:Abstract Seasonal changes of field populations and growth rates of two dinoflagellates, Ceratium furca and Ceratium fusus, were examined in the temperate coastal water of Sagami Bay, Japan. Weekly field sampling was conducted from August 2002 to August 2003, and laboratory experiments were also carried out to investigate effects of temperature, irradiance and photoperiod on the growth rates of these two Ceratium species. In the field, the abundances of both species increased significantly from April to August 2003, were gradually decreased from November 2002 and were not observed in January 2003. C. fusus was able to increase at lower temperatures in February 2003 compared to C. furca. In the laboratory, the two species did not grow at 32 °C. The highest specific growth rate of C. furca was 0.72 d−1 at 24 °C and 600 μmol m−2 s−1. Optimum growth rates (>0.4 d−1) of C. furca were observed at temperatures from 18 to 28 °C and at irradiances from 216 to 796 μmol m−2 s−1. The highest growth rate of C. fusus was 0.56 d−1 at 26 °C and 216 μmol m−2 s−1. Optimum growth rates of C. fusus were observed at the same irradiance rage of C. furca, whereas optimum temperature range was narrower (26–28 °C). The growth curves of both species indicated saturation of the growth rates when light intensity was above 216 μmol m−2 s−1, and did not show photoinhibition at irradiances up to 796 μmol m−2 s−1. The specific growth rates of both Ceratium species were clearly decreased at L:D = 10:14 relative to those at L:D = 14:10 and L:D = 12:12. The present study indicates the two Ceratium species can adapt to a wide range of temperature and irradiance.
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commentary gomez f moreira d and lopez garcia p 2010 neoCeratium gen nov a new genus for all marine species currently assigned to Ceratium dinophyceae protist 161 35 54
Protist, 2010Co-Authors: António J. Calado, John M HuismanAbstract:The recent publication by Gomez et al. (2010) described DNA sequence studies that demonstrated a taxonomic distinction between the freshwater and marine taxa of the dinoflagellate genus Ceratium. Since the type of Ceratium is a freshwater species, a segregate genus for the marine species was therefore required. The new genus name NeoCeratium was erected, with type species N. furca, and 76 additional new combinations in this genus proposed. In the discussion that accompanied the description, the authors recognized that several legitimate generic names had been proposed in the nineteenth century for different species of Ceratium, but for various reasons these names were rejected, primarily, “to avoid potential confusion derived from the use of previous subgeneric names” (Gomez et al. 2010, p. 44).We contend that the reasons for rejecting these earlier legitimate generic names, each with their type species included in NeoCeratium as circumscribed by Gomez et al. (2010), were inadequate and that the name of the newly recognized genus should have been adopted from one of these historical names.
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On the identity of the type species of the genus Ceratium Schrank (Dinophyceae), with notes on C. hirundinella
Phycologia, 1997Co-Authors: António J. Calado, Jacob LarsenAbstract:Abstract The genus Ceratium Schrank (Dinophyceae) was originally described with two species, both of which have been indicated as the type of the genus in the modern literature. Ceratium pleuroceras Schrank is not a dinoflagellate and should not be regarded as the type. We argue that the other species, C. tetraceras Schrank, should be regarded as the lectotype, and in turn synonymous with the freshwater species C. hirundinella (O.F. Muller) Dujardin. In practice, this means that C. hirundinella becomes the type of the genus. Citations of either Schrank or Bergh as authors of the combination C. hirundinella are most often found in the literature, but are incorrect. Ceratium furcoides (Levander) Langhans, presently recognized as an independent species, has been included by many workers in C. hirundinella; much information referred to C. hirundinella may, therefore, pertain instead or also to C. furcoides.