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Daily field surveys were conducted at a coastal-shelf station in Sagami Bay, Japan after the passage of typhoon Malou in 2010 to evaluate the after-effect of a typhoon passage on the physical-chemical environment, phytoplankton bloom formation and microbial processes within and below the euphotic layer. The passage of Malou induced an abrupt decrease in salinity and increased loading of nutrients to the euphotic layer. Dinoflagellates dominated the phytoplankton community at the surface, whereas diatoms dominated below the surface just after the passage of Malou. Four days later, the dominant dinoflagellate taxa at the surface changed from Protoperidinium spp. to Prorocentrum spp. and Ceratium spp., indicating a dinoflagellate community succession from heterotrophic to autotrophic functional groups. Five days after passage, the dominant phytoplankton taxa shifted from dinoflagellates to diatom groups of Chaetoceros spp. and Cerataulina spp. throughout the water column. Below the euphotic layer, there were increases in diatom frustules, mainly composed of Chaetoceros spp. and Cerataulina spp., bacterial abundance and NH4+ concentrations. Diatom carbon biomass contributed to approximately half of particulate organic carbon (POC) below the euphotic layer, suggesting a significant contribution of diatoms to POC sinking flux after the passage of a typhoon. Bacterial abundance was positively correlated to both phaeopigment concentrations (p

A new species of Leptostraca,Nebalia tagirisp. nov.is described and illustrated. This species was sampled from 200 m depth at a hydrothermal field in Wakamiko Caldera of Kagoshima Bay, Japan.Nebalia tagirisp. nov.is different from knownNebaliaspecies as follows: rostral length 2.4 times as long as width; article 4 of antennule with 3–5 robust distal spines; antennular scale approximately twice as long as wide; article 3 of antenna with eight spines and nine spine-like setae along proximal half, two thin setae and six spine-like setae on external lateral face, six spines and four simple setae on distal margin; article 1 of second maxilla longer than article 2; article 2 of mandibular palp with two thin setae; exopod of pleopod 1 with 21 spines along lateral margin; furcal rami longer than combined length of pleonite 7 and telson; rounded denticles of pleonite 6 and 7; anal-plates ‘shoulder’ not distinct. Furthermore, this specimen is the first genusNebaliafound in the hydrothermal vent. The distribution and ecology of this new species is also discussed and a key to all species ofNebaliais provided.

We studied seasonal and regional change in vertical distribution and DVM patterns of four euphausiid species (Euphausia pacifica, Thysanoessa inspinata, Thysanoessa longipes, and Tessarabrachion oculatum) from two years of surveys using MOCNESS above 1500 m depth across a transect in 3 regions of the northwestern (NW) Pacific, off east of Japan; Oyashio, Kuroshio, and Oyashio–Kuroshio Mixed Water Regions (MWR). The four euphausiid species exhibited a regional change in vertical distribution, i.e., slightly deeper in the MWR and much deeper in the Kuroshio region than in the Oyashio region. They found in higher and wider temperature ranges in the MWR than in the Oyashio region, which demonstrated that the four species were able to adapt to different temperatures in different regions. In the MWR and Oyashio regions, E. pacifica is a surface migrant (differences between day and night mean median depths, D-N, were ca. 300 m) and T. oculatum is a moderate subsurface migrant that performs short DVM in the upper mesopelagic zone (D-N ca. 100 m). The other two morphologically similar Thysanoessa species (T. inspinata and T. longipes) segregated vertically between E. pacifica and T. oculatum at night in the Oyashio region, suggesting vertical habitat partitioning with the former two species but not with themselves. However, a seasonal pattern was observed in the vertical distribution and DVM of T. longipes in the Oyashio region. It behaves as a surface migrant in May, whereas most of individuals were found in the mesopelagic layer in September. In contrast, T. inspinata did not exhibit a clear DVM throughout the year (i.e., a moderate subsurface migrant). This seasonal difference might be a strategy to minimize competition between related species. Among the four species, only E. pacifica was found in higher temperatures at night than during the daytime, and the highest temperatures at the median depth varied among species (from 7.5 °C to 13.7 °C) although the lowest temperature did not vary greatly (from 1.0 °C to 1.8 °C), which indicates high temperatures act as a limiting factor as opposed to low temperatures. Furthermore, the integrated chlorophyll a values exhibited significant negative correlation with median depths of only E. pacifica at night. These results indicate a strategy which makes E. pacifica the dominant species in the area, that is, it has a trade-off of long migrations and a warmer environment that accelerates metabolism, in return for obtaining a food-rich environment.

The relationship between euphausiid community structure and water region was studied during a 2-year seasonal survey in the northwestern (NW) Pacific Ocean. The euphausiid community structure and its associated species were analyzed from 38 micronekton samples collected during eight cruises. The euphausiid community structure and its distribution patterns clearly corresponded to physical oceanographic features in the Oyashio region, Oyashio–Kuroshio Mixed Water Region (OKMWR), and Kuroshio region. In contrast, community structure was unrelated to seasonality. The 19 species out of 40 identified in this area were grouped and named after their habitats. The six cold-water species were grouped into three regional types: two coastal Oyashio species, three Oyashio–OKMWR species, and one Oyashio–Kuroshio species. The four species dominating in the OKMWR were categorized into each specific types: Nematoscelis difficilis as OKMWR–Oyashio species, Euphausia gibboides as OKMWR species, Euphausia similis as OKMWR–Oyashio & OKMWR–Kuroshio species, and Euphausia recurva as OKMWR–Kuroshio species. The seven warm-water species were categorized as Kuroshio–OKMWR species or Kuroshio species. The other two species were categorized as cosmopolitan species. In particular, regarding the result in the OKMWR, our study suggest that (1) the OKMWR has high species diversity, and (2) the dominant species, such as Euphausia pacifica, N. difficilis, E. similis, and E. gibboides, are considered to be key species in the food webs in this region.

A new species of Leptostraca, Nebalia terazakii sp. n. is described and figured. The species was sampled from the coral reefs of Pulau Payar Marine Park, Langkawi, Malaysia. There are 32 existing species of Nebalia but Nebalia terazakii sp. n. can be distinguished from the other known species of Nebalia by the following combination of characters: the rostrum is 1.89 times as long as wide and the eyes have no dorsal papilla or lobes. Article 4 of the antennular peduncle has one short thick distal spine. The proximal article of the endopod of maxilla 2 is shorter than the distal, a feature peculiar to Nebalia terazakii sp. n., the exopod of maxilla 2 is longer than article 1 of the endopod, the posterior dorsal borders of the pleonites 6 to 7 are provided with distally sharp denticles, anal plate with prominent lateral shoulder and finally, the terminal seta of the caudal rami is 1.17 times the length of the entire rami.

The diversity of protistan microplankton in Sagami Bay was revealed by 18S rRNA gene clone analysis using newly designed PCR primers. PCR amplification consisted of a first reaction targeting the V3–V5 region of the 18S rRNA gene, followed by a nested reaction targeting the V3–V4 region. In total, 629 clones consisting of 108 phylotypes were affiliated with a variety of protistan groups including dinoflagellates, diatoms, prymnesiomonada, chlorophyta, ciliophora, cercozoa, and heterokonta. The dinoflagellate group was detected most frequently and shared approximately 74 % of the total clones. Within this group, approximately half of the clones belonged to the parasitic dinoflagellate Syndiniales group I, which was first reported from Sagami Bay. The genera Woloszynskia, Gonyaulax, Neoceratium, and Karlodinium have not been reported from this bay until now. The second most frequent group was diatoms, which shared approximately 22 % of the total clones. Within this group, highly diverse Thalassiosira phylotypes were detected, and they shared approximately 70 % of the diatom clones. Therefore, highly diverse protists including some candidate groups were successfully detected, indicating that the designed primers and PCR protocol will be useful for molecular diversity analyses of protistan microplankton communities in aquatic environments.

The diversity and short-term changes in the protistan microplankton community from April to June 2006 in Sagami Bay were revealed by 18S rRNA gene clone analysis. A total of 1,076 clones consisted of 68 phylotypes of dinoflagellates, 96 phylotypes of diatoms and 27 phylotypes of other protists affiliated with Ciliophora, Prymnesio- monada, Chlorophyta, Cercozoa, Chytridiomycota, and Heterokonta. Approximately half of all dinoflagellate phylo- types were affiliated with the following genera: Ceratium, Gonyaulax, Gymnodinium, Gyrodinium, Lepidodinium, Neoceratium, Prorocentrum, and Woloszynskia. The other half was classified into seven uncultured groups. These di- noflagellate clones were mostly detected in May, in contrast to the diatom clones, which were detected frequently throughout the study period. Diatoms were diverse and consisted of 14 genera and three uncultured groups. The gen- era Discostella, Thalassiosira and Skeletonema were dominant in April, May and June, respectively. Species richness (number of phylotypes) and diversity (Shannon-Weiner) of the whole protistan microplankton community were high- est in May. This is the first example of a comprehensive molecular biological analysis of protistan microplankton community structure, and the results clearly showed a dynamic shift in the protistan community in coastal waters from April to June in Sagami Bay. The results of a direct comparison between the clone analysis and microscopic ob- servations indicated that the clone analysis had the great advantage of enabling identification of plankton that were morphologically indistinguishable, and to reveal detailed information on the biodiversity of protistan microplankton. This advancement in molecular biological analysis will assist in our understanding of the biodiversity of protistan mi

The stochastic and elite models have been proposed for the mechanism of induced pluripotent stem (iPS) cell generation. In this study we report a system that supports the elite model. We previously identified multilineage-differentiating stress-enduring (Muse) cells in human dermal fibroblasts that are characterized by stress tolerance, expression of pluripotency markers, self-renewal, and the ability to differentiate into endodermal-, mesodermal-, and ectodermal-lineage cells from a single cell. They can be isolated as stage-specific embryonic antigen-3/CD105 double-positive cells. When human fibroblasts were separated into Muse and non-Muse cells and transduced with Oct3/4 , Sox2 , Klf4 , and c-Myc , iPS cells were generated exclusively from Muse cells but not from non-Muse cells. Although some colonies were formed from non-Muse cells, they were unlike iPS cells. Furthermore, epigenetic alterations were not seen, and some of the major pluripotency markers were not expressed for the entire period during iPS cell generation. These findings were confirmed further using cells transduced with a single polycistronic virus vector encoding all four factors. The results demonstrate that in adult human fibroblasts a subset of preexisting adult stem cells whose properties are similar in some respects to those of iPS cells selectively become iPS cells, but the remaining cells make no contribution to the generation of iPS cells. Therefore this system seems to fit the elite model rather than the stochastic model.

We surveyed the distribution of colonies of polyps of Aurelia aurita sensu lato (s.l.) in Mikawa Bay, Japan. First, we surveyed the distribution of ephyrae of A. aurita s.l. at 75 stations encompassing the whole of Mikawa Bay in early 2008. A total of 37 ephyrae were sampled mostly from fishing ports. Ephyrae were most abundant around the islands located near the mouth of the bay, and decreased from the western part to the eastern part of Mikawa Bay. Next, we selected five fishing ports in Mikawa Bay where ephyrae occurred and surveyed the underside of floating piers and underwater overhangs of wharfs. We found dense colonies of polyps of A. aurita s.l. under nearly all of the floating piers at the two islands located near the mouth of the bay. Fitting a logistic regression model to the dataset showed that the percentage coverage of Aurelia polyps was significantly greater at the two islands compared with the other locations. In addition, the coverage of Aurelia polyps was greater when the coverage of other fouling organisms was in the range of 65–90%, and the coverage of Aurelia polyps was lower on floating piers with a vinyl surface and on concrete wharfs. The combined distribution of polyp colonies of A. aurita s.l. in Ise Bay and Mikawa Bay suggested that A. aurita s.l. in the two bays probably forms a single population and shoals of medusae mainly originate from protected harbors along the mouth-part of the bays.

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.

To assess the consequences of bottom-up effects on phytoplankton community composition during the rainy season, phytoplankton levels and environmental factors were monitored daily from 12 April to 22 July 2003 in Sagami Bay, Japan. The relevant environmental factors were analyzed using cross-correlation analyses. Based on time-series analysis, low surface salinity conditions lasting 0 or 2 days after heavy rainfalls resulted in significant nutrient loading, such as dissolved inorganic nitrogen (DIN), into the coastal area. Also, Chlorophyll-a (Chl-a) concentration frequently increased 2 and 6 days after rainfall. Based on the high total Chl-a concentration, the time was divided into three periods, from 1 to 11 May (Period A), 26 May to 9 June (Period B) and 30 June to 22 July (Period C). The phytoplankton assemblages during Period A were dominated by two dinoflagellates, Ceratium furca and Ceratium fusus. Prior to these species blooming, the heterotrophic dinoflagellate Noctiluca scintillans was dominant. During Period B, the phytoplankton communities were dominated primarily by the diatoms Rhizosolenia delicatula, Hemiaulus sinensis and Navicula spp. Finally, Cerataulina dentata, Rhizosolenia spp., Lauderia borealis and Neodelphineis pelagica were dominant during Period C. After increases in phytoplankton abundance, available nitrogen (N) and phosphorous (P) were consumed and exhausted, which were considered a potential cause of the shift in the dominant organisms from large diatoms to pico- and nano-plankton in the low Chl-a environment. In particular, silicate (Si) was not a major limiting factor for phytoplankton production, since the Si:DIN and Si:P ratios clearly demonstrated that there were no any potential stoichiometric Si limitations, and almost all silicate concentrations were > 2.0 µM during this study. Our results reveal that nutrient sources supplied by river discharge are a main cue for strong bottom–up effects on algal bloom succession during the early summer season in Sagami Bay.

The relationship between nutrients and phytoplankton dynamics was investigated daily from 12 April to 22 July 2003 in Sagami Bay, Japan. According to multidimensional scaling (MDS) and cluster analysis, phytoplankton community was divided into four distinct groups. The first group was consisted of centric diatom species, such as Guinardia spp., Detonula spp., Letocylindrus danicus, Skeletonema costatum, Eucampia zodiacus and Chaetoceros spp.. The second and third clusters comprised mainly diatoms and dinoflagellates, respectively. The other cluster was restricted to the samples collected during the last sampling period when the rainfall and river discharge was frequently recorded. Canonical correspondence analysis (CCA) was applied to analyze four groups respectively, which focused on the effects of nutrients concentration and ratio on phytoplankton variations. Based on CCA analysis, most species of centric diatom were negatively correlated with DSi concentrations and Si/N ratio. Nutrients were strongly limited phytoplankton growth during the summer when the rainfall was not observed, whereas river discharge by rainfall and counterclockwise coastal currents (although the surface circulation pattern is often altered by Kuroshio Current, the counterclockwise coastal currents are generally dominant) has brought phytoplankton population accumulation and triggered the micoalgae growth in western part of the bay. Phosphorous (P) was strongly limited after significantly increases in the phytoplankton abundances. However, silicate (Si) was not a major limiting factor for phytoplankton production, since Si/DIN and Si/P ratio did not create any potential stoichiometric limitation. This indicates that high Si availability contributes favorably to the maintenance of diatom ecosystems in Sagami Bay.

The effect of hydrostatic pressure on embryonic development of the calanoid copepod Calanus sinicus was studied. Differences of pressure effect among blastomere stages, 1-cell, 2-cell, 4-cell, 8-cell, 16-cell, blastula and limb-bud stage, were examined under two pressurizing conditions, abruptly (10 atm/min) and gradually (0.1 atm/min) increasing. Egg hatching success, deformity frequency and apoptotic cell degradation of hatched nauplii were examined. Egg hatching success rate was not significantly different between blastomere stages, and also between pressurizing conditions. Deformity frequencies of hatched nauplii were low in the early 1-cell and 2-cell stages, and high in the later blastula and limb-bud stages, in both abrupt and gradual pressurizing conditions. On the other hand, in regard to difference in pressurizing conditions, deformity frequency in gradual pressurizing was significantly higher than that in abrupt pressurizing rate. Gradual pressure increase seems to be more harmful to C. sinicus eggs than abrupt pressure change. Apoptosis induced in nauplii by hydrostatic pressure was detected for the first time in marine zooplankton. The embryos of C. sinicus are sensitive to pressure variations, that is, these embryos are supposed to sink to deeper waters, incurring greater risk of having deformities. In the field, C. sinicus ascend to the surface and spawn at night. By looking from this upward behavior, eggs are spawned at lower pressure and warmer temperature. Probably, the harmless low pressure and warm temperature lead eggs to hatch early and to recruit successfully.

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.

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

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.

The seasonal abundance of the dominant dinoflagellate, Ceratium fusus, was investigated from January 2000 to December 2003 in a coastal region of Sagami Bay, Japan. The growth of this species was also examined under laboratory conditions. In Sagami Bay, C. fusus increased significantly from April to September, and decreased from November to February, though it was found at all times through out the observation period. C. fusus increased markedly in September 2001 and August 2003 after heavy rainfalls that produced pycnoclines. Rapid growth was observed over a salinity range of 24 to 30, with the highest specific rate of 0.59 d−1 measured under the following conditions: salinity 27, temperature 24°C, photon irradiance 600 µmol m−2s−1. The growth rate of C. fusus increased with increasing irradiance from 58 to 216 µmol m−2s−1, plateauing between 216 and 796 µmol m−2s−1 under all temperature and salinity treatments (except at a temperature of 12°C). Both field and laboratory experiments indicated that C. fusus has the ability to grow under wide ranges of water temperatures (14–28°C), salinities (20–34), and photon irradiance (50–800 µmol m−2s−1); it is also able to grow at low nutrient concentrations. This physiological flexibility ensures that populations persist when bloom conditions come to an end.

Bacterial abundance determined with SYBR Green I and 4� 6-diamidino-2-phenylindole (DAPI) methods were compared using the protocol for each method employing epifluorescence microscopy. This comparison, using seawater samples that were col- lected from Sagami Bay, revealed that the abundance determined with the SYBR Green I method was on average 1.6 fold greater than that with the DAPI method. A model 2 regression analysis showed the following relationship: Log SYBR Green I�� 0.238� 1.08 Log DAPI (r 2 � 0.85, n� 68, p� 0.0001). These results suggest that when the method is switched between the SYBR Green I and DAPI methods, the difference in bacterial abundance determined by the two methods should be con- sidered for a quantitatively consistent assessment of the bacterial biomass in the ocean.

In order to study the mechanism of the bloom formation of Noctiluca scintillans, the relationship between the variation in the abundance of N. scintillans and environmental factors was examined in the coastal waters of Sagami Bay, Japan. Hydrographic (temperature, salinity, water stability), biological (chlorophyll a concentration, zooplankton biomass) and meteorological (rainfall, wind velocity, wind direction) factors were investigated from 1997 to 2004. For all years, the abundance of N. scintillans started to increase from March and reached a maximum in spring between April and May. The abundance in 1997 and 2000 was relatively high compared to the other years while the abundance in 1998 and 2004 was relatively low. A stepwise multiple linear regression analysis showed that the wind direction and rainfall were significantly correlated with the variation in the abundance of N. scintillans. Our results suggest that bloom formation can be separated into a threestep process: (i) initial increase in the abundance of N. scintillans attributed to an increase in optimum hydrographic and biological factors, (ii) N. scintillans is then accumulated by convergence of seawater by the factors of low rainfall and wind and (iii) swarmer-effects suggested enhanced bloom formation. Accumulation is considered to be a key trigger in this process of the formation of large-scale blooms.

Seasonal changes in diversity and community structure of planktonic copepods at a shelf site in Sagami Bay, Japan was studied in relation to cross-shelf interaction of species components. Seasonal mesozooplankton samples were collected from the shelf station (St. M) of the north-west part of Sagami Bay from 1995 to 1997. Vertical multi-layered samples were collected near the center of Sagami Bay (St. P) in June 1996. A total 185 copepod species were identified from the two stations. We observed a clear seasonal succession in calanoid diversity and community structure at St. M from a simple shelf water community (>11 species) during spring blooming periods to highly diverse and mixed communities (ca 20–30 species) of shelf water species coupled with various Kuroshio Current species during late summer to autumn. Cluster and non-metric multidimensional scaling ordination analyses showed two distinct calanoid community groups. One group, which included samples of St. M and the surface layer of St. P, consisted of shelf water species, such as Calanus sinicus, Ctenocalanus vanus, Paracalanus spp., and Kuroshio species, such as, Canthocalanus pauper, Scolecithrix danae, etc. The other cluster was restricted to the samples collected from mid and deep layers at St. P, which consisted of meso- and bathypelagic species and Oyashio species (cold-current species, such as Neocalanus cristatus, Pseudocalanus spp., Eucalanus bungii and Metridia pacifica). In the mid and deep layers at St. P, the population of dormant copepodid stage V (CV) of Eucalanus californicus and C. sinicus were dominant. The deep CV population of C. sinicus might be ecologically discriminated from the surface and shelf water population due to their larger body length and dormant life cycle. E. californicus was also collected at the shelf site during each spring bloom period, whereas the population might descend into the mid- and deep-layers of the central bay before summer. Our results suggest that the seasonal fluctuation of community structure in the shelf water was controlled by both physical (Kuroshio Current) and biological factors, i.e., spring bloom and ontogenetic vertical migration of E. californicus. In particular, transport and diffusion processes of Kuroshio Current in Sagami Bay played a key role in controlling the shelf water calanoid community.

A dense occurrence of the ctenophore Bolinopsis infundibulum was observed at depths of approx. 1250 m from the manned submersible SHINKAI 2000 from 1998 to 2000 near the seafloor off Kushiro, Hokkaido, Japan. Body length ranged from 6.5 to 16.5 cm for seven specimens sampled from the submersible. Horizontal transects by the submersible showed that B. infundibulum were scarce shallower than 1000 m, but were abundant within 30 m of the bottom, ca. 0.8 ctenophore m � 3 , then decreasing gradually to 80 m above the seafloor. The ctenophores forage with extended oral lobes and hanging quiescently in the water column. Ninety ctenophores among 112 observed at 1200–1270-m depth were in the foraging posture. One individual captured at depth had a female C5 stage of Neocalanus cristatus and fragments of calanoids (? Aetideidae) in its gut. Carbon and nitrogen stable isotope ratio data indicated that the B. infundibulum relied on surface photosynthetic products for food and their position in the trophic pyramid is relatively low. B. infundibulum feeds mainly on copepods, at least some part of which consist of carbon-rich copepods such as Neocalanus spp. and Eucalanus bungii, which grow in surface layers but sink to depth when diapausing as C5 or adult stages. Carbon-based estimations showed that one Neocalanus cristatus C5 or 4–6 N. plumchrus+flemingeri C5+female are sufficient for daily maintenance of a medium-sized (B10 cm) B. infundibulum. Considering the abundance of B. infundibulum, we conclude that this deep ctenophore population may contribute substantially to the mortality of these epipelagic copepods during diapause. r 2003 Elsevier Science Ltd. All rights reserved.

The relationship between the xanthophyll pool [diadinoxanthin plus diatoxanthin normalized to chlorophyll (Chl) a] and irradiance was examined during phytoplankton blooms in Sagami Bay from the end of April to July 2000. In the case of Chl a concentrations >2 mg m -3 , a linear correlation was found between the xanthophyll pool and irradiance of the previous day. On the other hand, for Chl a concentrations

A new Ryocalanoid copepod, Ryocalanus spinifrons, collected by the MTD net system at a depth of 1400 m from the southwestern part of Sagami Bay, Japan, is described. The new species is morphologically very close to R. infelix Tanaka, 1956 (female unknown) from the Izu region of Sagami Bay. It is distinguished from other species by the presence of 12 long spinules on the ventral inner side of the fifth pedigerous somite, nine setae on the coxal epipodite of the maxillule and nine large robust spinules on the coxal segment of the fourth leg. The row of five robust spines on the paragnath distinguishes R. spinifrons.

Cyanobacteria were relatively small contributors to carbon biomass (0.97-18%) in the euphotic zone. However, a higher contribution to production obtained at the surface water (16-45%) implies that they contribute more to carbon cycling than is expected from their biomass.

Twenty-six specimens representing 2 genera, Alvinocaris of the family Bresiliidae and Lebbeus of the Hippolytidae, were found in samples collected from hydrothermal fields in the Okinawa Trough, Japan. Twenty-one specimens are described as Alvinocaris longirostris, new species, and the remaining 5 are redescribed as a very rare bathyal shrimp, Lebbeus washingtonianus (Rathbun, 1902).

SYBR Gold staining is used for enumerating bacteria and viruses in aquatic samples. However, its suitability for epifluorescence microscopy has not been sufficiently investigated. Thus we compared bacterial and viral counts using SYBR Gold and SYBR Green I stains. Variables for both bacterial and viral counts included season and ocean depths of sample collection and the period of sustained excitation under epifluorescence microscopy. We also examined the storage period and procedures for preservation of samples with formaldehyde for bacterial counts. Natural seawater samples were used for all experiments. Ratios of counts obtained with SYBR Gold to those with SYBR Green I staining were 0.99 ± 0.09 (mean ± SD, n = 58) for bacteria and 1.0 ± 0.1 (n = 38) for viruses, which indicated no significant differences between stains. In samples fixed with 0.74% formalde- hyde that were stored at 4°C, bacterial counts obtained with SYBR Gold staining decreased over time in parallel with those obtained with SYBR Green I staining. However, counts from fixed samples with both SYBR stains did not decrease significantly after 30 d when glass slides were prepared immedi- ately and stored at -20°C, or when samples were flash-frozen in liquid nitrogen and stored at -80°C. Under sustained excitation, counts of bacteria and viruses stained with SYBR Gold decreased less than with SYBR Green I, suggesting greater persistence of the fluorescence signal with SYBR Gold. These results indicate the suitability of SYBR Gold staining for use in the determination of bacterial and viral abundance in natural seawater.

Three species of Sicyonella, S. antennata, S. inermis, and S. maldivensis, were redescribed and illustrated in detail. In addition to characters of the antennular peduncle and petasma, the three species are distinguished by the shape and armature of the proximal part of the mesial antennular flagellum of the male, the color of the antennal flagellum, the number and size of spiniform setae on the distomesial corner of the sympod of the second, third, and fifth pleopods, and the shape of the thelycum. On the basis of these characters, a female of the syntype of S. maldivensis from Mauritius was identified as S. inermis. Therefore, a male of the syntype from the Maldives is designated the lectotype of S. maldivensis.

Vertical distributions and patterns of diel vertical migration of pelagic shrimps were analyzed at two locations in the western North Pacific. In all, 47 discrete samples were taken using a KOC sampler from 7 layers between 150 and 4000 m at around 40°00'N, 150°00'E in May to June 1981 and from 17 layers between 150 and 6100 m at around 30°00'N, 147°00'E in June 1982. In the former location on the subarctic boundary, 32 species of 12 genera, and in the latter location in the North Pacific central waters, 49 species of 19 genera were found, respectively. In the two locations, both the abundance and biomass decreased exponentially with depth, and the shrimp ultimately disappeared at about 6000 m depth. Vertical distribution of shrimps was generally deeper in the southern waters than the northern waters. Shrimps were classified into five groups according to their vertical distribution. Those living above 600 to `000 m performed marked diel migrations, whereas those at depths >600 to 1000 m did not show apparent diel migration. These results suggest that the vertical flux of biomass of bathypelagic shrimp is much smaller than that of epi- and mesopelagic shrimps.