• 한국해양학회지
• /
• v.22 no.3
• /
• pp.179-190
• /
• 1987

A study on the fine structure of the marine diatoms has been carried out for taxonomical purpose during the periods from September 1983 to March 1987 in Korean coastal waters. Fine structure of smallThalassiosira(Bacillariophyceae) was studied by means of light microscope and scanning electron nisroscopy. Secondarily, six species of Thalassiosira were identified and described. Of these Thalassiosia allenii, T. binata and T. conferta were new records for Korean coastal waters. Thalassiosira aestivalis, T.allenii, T.binata, T.conferta, and T. pacifica have a valve with a single labiate process and one central and one marginal ring of strutted processes, but T.rotula has many central strutted processes close together instead of one central strutted process.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.3
• /
• pp.359-367
• /
• 1999

For investigating the activities of algicidal bacteria, the variations of algicidal bacterial population and chlorophyll-a were checked weekly in Chindong Bay, Korea from May to July, 1998. For identifying their killing characteristics, three strains were selected from the isolated algicidal bacteria. The density of algicidal bacteria kept changing in the range of $6.0\times10^1$ to $6.4\times10^5$ cell $\ell^{-1}$. The density flux of algicidal bacteria coincided with that of chlorophyll-a by a week of lag time. Three algicidal bacteria isolated from field strains, H519S5-4, H605S5-15 and H605S5-22, were investigated in nine microalgal species, Heterosigma akashiwo, Chattonella sp. (Raphidlphyceae), Gymnodinium catenatum, Gyrodinium impudicum, Cochlodinium polyklikoides (Dinophyceae), Chaetoceros sp., Coscinodiscus granii, Ditylum brightwellii, Thalassiosira rotula (Bacillariophyceae). Strain H605S5-22 showed a wide algicidal activities over nine microlgae, strain H605S5-15 over H. akashiwo, G. catenatum, T. rotula, Chattonella sp. and strain H519S5-4 over H. akashiwo, Chattonella sp., Chaetoceros sp., G. catenatum. The activities of the three strains were detected by the secretion of algicidal substances. Therefore, it is suggested that the activities of algicidal bacteria have a significant influence over the population dynamics of phytoplankton and get involved with the sharp decrease in red tides in the coastal area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.15 no.1
• /
• pp.1-7
• /
• 2010

We were successfully reared young marine ornamental larva fish in a unique process of microalgae blooming culture tank. The marine fish larva was grown and survived in this method. Generally, we called this method as natural mixed culture. Observed planktonic microalgae were 34 species with 19 diatoms (Detonula pumila, Nitzschia sp., Fragilaria oceanica, Chaetoceros curvisetus, Stephanodiscus sp., Chaetoceros decipies, Chaetoceros sp., Thalassiosira rotula, Eucampia zodiacus, Diploneis splendica, Nitzschia longissima, Surirella cuneata, Asterionella glacialis, Nitzschia spp., Chaetoceros debile, Thalassionema nitzschioides, Nitzschia closterium, Skeletonema costatum and Licmophora sp.), 14 flagellates (Euglena, sp., Gonyaulax sp., Pyramimonas sp., Protoperidinium sp., Eutreptia sp., Parapedinella sp., unidentified micrc-flagellate, Gyrodinium sp., Scrippsiell trochoidea, Gymnodinium sanguineum, Chrysochromulina sp., Gymnodinium sp., Prorocentrum triestinum and Micromonas sp.) and 1 ciliate (Mesodinium rubrum) in this culture tank. Dominant microalgae were Chrysochromulina sp. during the larval rearing periods. Blooming condition maintained continuously and stably from 10 to 60 days in this microcosm.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.16 no.4
• /
• pp.238-245
• /
• 2011

Phytoplankton community composition was investigated in the Asan Bay (South) Korea. Water samples were collected monthly from five stations during January to December 2008. Phytoplankton blooms were observed in February and in August but the location of the bloom varied with the sampling time. A total of 134 phytoplankton species from seven classes (Bacillariophyceae, Chlorophyceae, Chrysophyceae, Cryptophyceae, Cyanophyceae, Dinophyceae, Euglenophyceae) were observed. Diatoms were dominant in all stations through-out the year except in summer when dinoflagellates were numerous and highly distributed within the outer bay rather than in the river mouth. Dominant and subdominant species were composed mostly of diatoms but were replaced by dinoflagellates in June and July. Results of ecological index showed that the diversity indices were increasing toward outer bay but the dominance indices showed a reverse trend.

• Journal of Environmental Science International
• /
• v.14 no.2
• /
• pp.177-184
• /
• 2005

This study was to determine the fluctuation in phytoplankton assemblages with regarding to environmental conditions and nutrients, which were surveyed around Mokpo waters in the southwestern waters, Korea. Sampling was carried out on the Mokpo, Sinan, and Wando coasts from March to November 2003. The maximum sea surface temperature was recorded in August, and it ranged around $25^{\circ}C$ regardless of sampling sites. However, salinity in Mokpo waters showed a great variation, which ranged from 5-30 psu and recoded the minimum of 5 psu in July and the maximum of 30 psu in November. Moreover, in Mokpo waters, the chlorophyll a and SS concentration of the surface layer were also the highest values of $20\;{\mu}g\;l^{-1}\;and\;40\;{\mu}g\;l^{-1}$, respectively than those of Sinan and Wando waters. The concentrations of $NH_4-N,\;NO_2-N,\;NO_3-N,\;and\;PO_4-P$ were also he highest values of $0.018\;{\mu}mol\;^l{-1},\;0.062\;{\mu}mol\;l^{-1},\;1.2\;{\mu}mol\;l^{-1}\;and\;0.078\;{\mu}mol\;l^{-1}$, respectively in Morpo waters than those of Sinan and Wando waters. During the period of this study, the majority of the taxa were diatoms; Thalassiosira rotula, Rhizosolenia setigera, Prorocentrum minimum, Chaetoceros curvisetus, Leptocylindrus danicus, Pseudonitzschia pungens, and Chaetoceros spp. were detected in the dominant species of phytoplankton. The dinoflagellates were relatively abundant during the summer season in Wando waters, which attained an abundance of $10-20\%$. In Mokpo waters, DIN/DIP was the highest value of 700 in March, whereas the lowest was shown in Wando waters. However, DIN/DIP value in summer at Wando waters was extremely reversed, which appeared to be associated with the development of dinoflagellates. On the bais of factor analysis using SYSAT 6.0, nutrient showed somewhat correlation with chlorophyll a. Consequently, the process of discharge of fresh water in Mokpo waters plays an important role in extremely fluctuation in nutrients and conditions. Although Wando waters maintains a lack of nutrients, it should be influenced by different water current and may be associated with a concentration of nutrients.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.22 no.4
• /
• pp.1-20
• /
• 1986

Physical, chemical and biological surveys on Nakdong River estuary were made from October, 1985 to September, 1986. 1. For all the seasons except summer, the sea surface temperature in northwest area of the line which linked from Seo Island to Jisim Island was I-2$^{\circ}$C lower than in southeast area, but in summer the sea surface temperature in northwest area was I-2$^{\circ}$C higher than in southeast area. On the contrary, bottom temperature of coastal area was 1$^{\circ}$C higher than that of oceanic area except winter. 2. Surface salinity in summer and fall has minimum value of 1. 9%0 and maximum value of 32.9%0. This large variation was caused by the runoff of the Nakdong River. Effect of less saline Nakdong River water in northwest area of the line which linked from Seo Island to Jisim Island was greater than in southeast area. A strong current rip always formed near this line. 3. The yellowish-green colored zone was observed in the Nakdong River estuary throughout the year by influence of river discharge. The characteristics of the water quality in the zone have shown that the water color was grade 7 by the Forel water-color meter, transparency was less than 4 m, and concentration of suspended solids was more than 5 mg/1. This water body was in the state of eutrophication in terms of chlorophyll-a and inorganic nitrogen concentration during summer season. 4. During the study period, total 276 taxa were identified. Most of them were diatoms and dinoflagellates which consisted of 97.5%. The component ratio of the above two groups was 84.4% and 13.1 % respectively. Diatoms were plentiful in December and dinoflagellates in July. Dominant species were Nitzschia seriata in October, Thalassiosira rotula in December, Skeletoncma costatum in April, and Nitzschia longissima in July. 5. A total of 47 zooplankton taxa was identified from the samples collected. Copepods were numerically the most important components of zooplankton communities in the study area. The domir:ant copepod species were Paracalanus parvus, Acartia clausi and Temora turbinata. Noctiluca scintillans was the next important component. The other zooplankton with minor abundance were Cladocera. Sagitta spp., Cnidaria, Mysidacea, Lucifer spp. and Amphipoda. 6. During the study period, fishes from 47 families and 87 species were sampled in th~ study area. The four most abundant fish species were Rep~mucen//'s valencicnnei, Leiognathus n~cha!is, Amblychaeturicllthys hexanema and Sardirel/a zun:zsi. The fish species of the secondary importance in abundance were Cynoglossus joyneri, Sillago sihama, Engra~lis japonicus, Encdrias nebulos'l, Acanthogobius flavimanus, Trichiurus lepturus, LiParis tanai/ai, Cynagloss//'s interruptus, Aj)ogon line:z!us, Thrissz la 1l.'1la!ensis, and Limanda yokohamac.