• Korean Journal of Environmental Biology
• /
• v.24 no.1 s.61
• /
• pp.81-88
• /
• 2006

The cell abundance and marker pigment distribution patterns of picophytoplankton in the Chuuk Lagoon, tropical South Pacific, were analyzed flow cytometry and HPLC. Also, respective contribution of Synechococcus, Prochlorococcus and picoeukaryotes on estimated carbon biomass was evaluated. Synechococcus and Prochlorococcus showed contrasting distributional patterns in the waters of Chuuk Lagoon. Relatively high concentration of Synechococcus was observed near Weno Island but the concentration decreased toward the Northeast Passage. However, Prochlorococcus showed an opposite distributional pattern. Picoeukaryotes did not show any significant variable difference. The range of divinyl chlorophyll a (Chl. $\alpha$) concentration, marker pigment of Prochlorococcus, was $1.2\sim180.3\;ng\;L^{-1}$ and higher concentrations were observed at the stations near the Northeast Passage than stations near Weno Island. This pigment pattern was similar to cell abundance pattern indicating that chi. a2 may be a useful biomass indicator. On the other hand, the range of zeaxanthin concentrations was $61.4\sim135.8\;ng\;L^{-1}$ showing comparatively less significant variation indicating zeaxanthin influence derived from Prochlorococcus. Estimated carbon biomass of Synechococcus contributed 68% of total picophytoplankton biomass. Prochlorococcus and picoeukaryotes respectively contributed 17.1% and 14.9% of total picophytoplankton biomass.

• ALGAE
• /
• v.30 no.3
• /
• pp.223-232
• /
• 2015

More than 20 and 10 clades / ecotypes of Synechococcus and Prochlorococcus, respectively, have been identified in various oceanic regions. However, their diversity has yet to be thoroughly studied in the northwest Pacific Ocean. Further, spatial distribution of Synechococcus clades in the oligotrophic oceans has been scarcely characterized. To elucidate picocyanobacterial lineage distribution in the northwest Pacific Ocean, 16S-23S internal transcribed spacer sequences of picocyanobacteria were sequenced by barcoded amplicon pyrosequencing method. Additional pyrosequencing library using a primer specific for the Synechococcus subcluster-5.1 was constructed to thoroughly understand Synechococcus diversity in the oligotrophic oceans. In warm pool area, Prochlorococcus was predominant and showed a distinct depthpartitioning between HLII and LL ecotypes. Despite low abundances, diverse Synechococcus clades appeared in the oligotrophic open ocean, showing both vertical and horizontal niche partitioning. Clade II was the predominant Synechococcus clade, especially in upper euphotic depths. In shallow and middle euphotic depths, clades UC-A, III, and CRD1 were distributed broadly. However, a distinct shift in the horizontal distribution was found at ca. $20^{\circ}N$. Conversely, clades XVII and CRD2 dominated at deep euphotic depths and constituted a higher proportion than clade II. These niche-partitioning of Synechococcus clades seemed to be related with temperature, nutrient concentration as well as iron concentration.

• Ocean and Polar Research
• /
• v.34 no.1
• /
• pp.19-28
• /
• 2012

In order to understand the spatial distribution of picocyanobacterial diversity during the summer in the northern East China Sea (ECS), their abundance and genetic diversity were investigated using flow cytometry and barcoded amplicon pyrosequencing of 16S-23S internal transcribed spacer sequences. Synechococcus abundance was high, with a range of $0.2{\times}10^5$ to $1.8{\times}10^5$ cells $ml^{-1}$. However, Prochlorococcus were found only in the eastern part of the studied area, showing a marked variation among stations [range of n.d. (not detected) to $3.3{\times}10^4$ cells $ml^{-1}$]. Eleven Synechococcus clades and five Prochlorococcus ecotypes were found to have a proportion higher than 1% among picocyanobacterial sequences, indicating high picocyanobacterial diversity in the ECS. The picocyanobacterial compositions were markedly different among stations, as well as among depths. Inflow of the Tsushima Warm Current and Changjiang diluted water was of primary importance in determining picocyanobacterial lineage diversity in the studied area. In addition, light intensity and nutrient conditions also appeared to be important in the vertical and horizontal distribution of picocyanobacterial diversity.

• Ocean and Polar Research
• /
• v.26 no.2
• /
• pp.273-286
• /
• 2004

The effects of environmental forcing on autotrophic picoplankton distributional patterns were investigated for convergence ($5^{\circ}N$), divergence ($9^{\circ}N-10^{\circ}30'N$) and oligotrophic ($17^{\circ}N$) sites in the tropical eastern Pacific during 2001 and 2003 KODOS (Korea Deep Ocean Study) cruises. The distributions of picoplankton populations - Prochlorococcus, Synechococcus and picoeukaryotes algae - were determined by flow cytometric analyses. Latitudinal variations in abundance maxima, vertical profiles, integrated abundance (0-150 m), and estimated carbon biomass were contrasted for each site according to three hydrological conditions. Prochlorococcus showed consistently high abundance in the surface mixed layers of all sites at $1\;{\times}\;10^5{\sim}3\;{\times}\;10^5\;cells\;ml^{-1}$ and showed declining abundance below these layers. However, these decreasing rates were not particularly sharp showing considerably high abundance at $1\;{\times}\;10^4\;cells\;ml^{-1}$ or higher even at 100 m depth. Vertical profiles of Synechococcus and picoeukaryotes were generally parallel to each other in all sites. A clear abundance maximum was observed at divergence site at or slightly above the pycnocline depth. Higher abundance was observed at the surface mixed layer for convergence site but a sharp decrease was observed below the pycnocline. However, there was no significant abundance fluctuation with depth at more oligotrophic site ($17^{\circ}N$). Integrated cell abundance of Prochlorococcus was high in the oligotrophic site at $2.17\;{\times}\;10^{13}\;m^{-2}$, and low in the convergence site at $0.88\;{\times}\;10^{13}\;m^{-2}$. However, opposite pattern was observed for Synechococcus and picoeukaryotes where relatively high integrated cell abundance was shown in the convergence site. Estimated carbon biomass of Prochlorococcus contributed 30.4-80.3% of total autotrophic picoplankton carbon showing the highest contribution in the oligotrophic site and the lowest contribution in the convergence site. Synechococcus contribution of total autotrophic picoplantkon carbon biomass was lower than 5.8% for most of sites except the convergence site where Synechococcus contributed 23.2% of picoplankton carbon biomass. Carbon biomass of picoeukaryotes was 18.8-46.4% showing the highest carbon biomass at the convergence site. Overall, Prochlorococcus showed higher cell abundance and carbon biomass and exhibited different reaction to hydrological conditions when compare with the other two major autotrophic picoplankton groups.

• Korean Journal of Environmental Biology
• /
• v.24 no.1 s.61
• /
• pp.67-80
• /
• 2006

The effect of environmental forcing on picophytoplankton distribution pattern was investigated in the tropical and subtropical western Pacific (TSWP) and the East Sea in September, 2002, and the continental shelf of the East China Sea (C-ECS) in August, 2003. The abundance of picophytoplankton populations, Synechococcus, Prochlorococcus and picoeukaryotes were determined by flow cytometry analyses. Picophytoplankton vertical profiles and integrated abundance $(0\sim100\;m)$ were compared with these three physiochemically different regions. Variation patterns of integrated cell abundance of Synechococcus and Prochlorococcus in these three regions showed contrasting results. Synechococcus showed average abundance of $84.5X10^{10}\;cells\;m^{-2}$, in the TSWP, $305.6X10^{10}\;cells\;m^{-2}$ in the C-ECS, and $125.4X10^{10}\;cells\; m^{-2}$ in the East Sea where increasing cell concentrations were observed in the region with abundant nutrient. On the other hand, Prochlorococcus showed average abundance of $504.5X10^{10}\;cells\;m^{-2}$ in the TSWP, $33.2x10^{10}\;cells\;m^{-2}$ in the C-ECS, and $130.2X10^{10}\;cells\;m^{-2}$ in the East Sea exhibiting a distinctive pattern of increasing cell abundance in oligotrophic warm water. Although picoeukaryotes showed a similar pattern to Synechococcus, the abundance was 1/10 of Synechococcus. Synechococcus and picoeukaryotes showed ubiquitous distribution whereas Prochlorococcus generally did not appear in the C-ECS and the East Sea with low salinity environment. The average depth profiles for Synechococcus and Prochlorococcus displayed uniform abundance in the surface mixed layer with a rapid decrease below the surface mixed layer. for Prochlorococcus, a similar rapid decreasing trend was not observed below the surface mixed layer of the TSWP, but Prochlorococcus continued to show high cell abundance even down to 100 m depth. Picoeukaryotes showed uniform abundance along $0\sim100\;m$ depth in the C-ECS, and abundance maximum layer appeared in the East Sea at $20\sim30\;m$ depth.

• Korean Journal of Environmental Biology
• /
• v.37 no.1
• /
• pp.93-108
• /
• 2019

To investigate the temporal-spatial distribution of picophytoplankton in relation to different water masses in the northern East China Sea (ECS), picophytoplankton abundance were investigated using flow cytometry with environmental factors in 2016-2017. The results from the analysis of flow cytometer data showed that Synechococcus appeared across all seasons, exhibiting its minimum abundance in winter and maximum abundance in summer. Furthermore, high abundance was detected in the surface mixed layer during spring and summer when vertical stratification occurs; in particular, Synechococcus exhibited maximum abundance in thermocline layer, indicating a close correlation to water temperature and thermocline formation. In addition, the abundance of Synechococcus indicated a decrease in the western seas in 2017 compared to 2016 under the strong influence of the Changjiang Diluted Water (CDW). This was determined by the significant influence of the CDW on the abundance of Synechococcus during summer in the northern waters of the ECS. In contrast, Prochlorococcus did not appear during winter and spring, and its distribution was limited during summer and autumn in the eastern seas under the influence of the Kuroshio current. The largest range of Prochlorococcus distribution was confirmed during autumn without the influence of the CDW. Thus, the distribution pattern of each picophytoplankton genus was found to be changing in accordance to the extension and reduction of sea current in different seasons and periods of time. This is anticipated to be a useful biological marker in understanding the distribution of sea currents and their influence in the northern waters of the ECS.

• Journal of Environmental Science International
• /
• v.17 no.11
• /
• pp.1243-1253
• /
• 2008

The seasonal variations of picoplankton including Prochlorococcus, Synechococcus and Picoeukayotes around Ulneung Island were investigated by flow cytometry in spring, summer and autumn in 2006. All groups of picoplankton showed clear seasonal patterns in population abundance. Among the group, Synechococcus showed the most prominent seasonal variation during the study period. The maximal abundance of Synechococcus occurred in summer and the lowest in autumn. The seasonal distribution of Prochlorococcus displayed the reverse tendency with that of Synechococcus. The abundance of Prochlorococcus ranged from $2.9{\times}10^3$ cells/ml in summer to $311{\times}10^3$ cells/ml in autumn. However, the seasonal distribution of Picoeukaryotes was shown to be relatively constant, and the maximal abundance was $81.5{\times}10^3$ cells/ml in summer. The highest abundance of Picoeukaryotes occurred in summer and the lowest in autumn and the seasonal distribution in abundance of Picoeukaryotes showed a similar trend with that of Synechococcus. The estimated total carbon biomass of picoplankton were ranged from $74.7\;mg\;C/m^2$ to $1,055.9\;mg\;C/m^2$. The highest total carbon biomass occurred in summer, but lowest occurred in autumn. The pattern of the contribution of three picoplankton to total autotrophic picoplankton carbon is different. The contribution of Synechococcus to total autotrophic picoplankton carbon is increased to 75%, but the contribution of Prochlorococcus dropped to 12% in summer. The contribution of Picoeukaryotes is ranged from 24% in summer to 72.5% in spring.

• Journal of Microbiology and Biotechnology
• /
• v.11 no.5
• /
• pp.899-901
• /
• 2001

Comparison of the abundances of heterotrophic bacteria in the East and South China Seas by stanctard epifluorescence was miscounted as heterotrophic bacteria in DAPI stained samples. This could result in 5-31% oversestimations of heterotrophic bacterial abundance in the study areas.

• Korean Journal of Microbiology
• /
• v.49 no.3
• /
• pp.237-244
• /
• 2013

Bacterial diversities in the guts of sea cucumbers (Apostichopus japonicus) and shrimps (Litopenaeus vannamei) were investigated using barcoded or tag-encoded 454 pyrosequencing of 16S rRNA genes. In sea cucumbers, most of sequences were related to two genera, the genus Propionigenium in the phylum Fusobacteria and an unclassified genus in the family Flavobacteriaceae of phylum Bacteroidetes. Shrimps showed various kinds of genera including Lactococcus, Leuconostoc, Prochlorococcus, and Vibrio as well as the unclassified genera in the families, Flavobacteriaceae, Rhodobacteraceae, Desulfobulbaceae, and Helicobacteraceae and in the order Mycoplasmatales. Unclassified genera containing environmental sequences only are more than half of genera from sea cucumbers and shrimps. Sea cucumbers and shrimps could be unexplored sources of novel microbes and the bacterial diversity of them was revealed by high throughput 454 pyrosequencing.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.20 no.4
• /
• pp.192-198
• /
• 2015

Picophytoplankton, a group of tiny microorganisms of less than $3{\mu}m$, play an important role as a major primary producer in tropical open ocean as well as temperate coastal waters. Until now, more than 20 and 10 clades of Synechococcus and Prochlorococcus, respectively, have been identified in various marine environments, and its biogeographical distribution have been well studied as well as ecological niches of its major clades. To understand a distribution of diverse picocyanobacterial clades and environmental factors regulating their distribution, picocyanobacterial abundance and genetic diversity was investigated in adjacent waters of Dokdo showing diverse physical properties not only by seasonal variation but also by diverse physical processes. Synechococcus abundances were low in winter and then exponentially increased as water temperature increased up to $20^{\circ}C$. Above $20^{\circ}C$, the abundances tended to be saturated. On the contrary, Prochlorococcus was undetected or occupied a minor fraction of picocyanobacteria in most seasons. In summer, however, Prochlorococcus belonging to HLII ecotype occupied a significant fraction (up to 7%) of picocyanobacteria. In spring and early summer, the steep increase of Synechococcus abundances were resulted from growth of cold water-adapted Synechococcus belonging to clades I and IV. In summer, diverse Synechococcus clades including warm and pelagic water-favoring clade II tended to replace clades I and IV with maintaining high abundance. The water-column stability as well as temperature were found to be important factors regulating the Synechococcus abundances. Moreover, inflow and mixing of distinct water masses with different origins exerted significant influence on the composition of Synechococcus in the study area. Thus, physical processes as well as natural seasonal variation of environmental factors should be considered to better understand ecology of planktonic organisms around Dokdo.