• ALGAE
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• v.18 no.4
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• pp.255-262
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• 2003

Ecological characteristics of phytoplankton communities were investigated biweekly at 6 stations from Feb. 2001 to Feb. 2002 at the lower part of the Han River. During the study, a total of 267 taxa which were composed of 114 green algae, 104 diatoms, 22 blue-green algae, 13 chrysophytes and 2 dinoflagellates were observed. The standing crops of phytoplankton communities were ranged from 1.30 ${\times}10^6$ cells ${\cdot}l^{-1}$ to 37.47 ${\times}10^6$ cells ${\cdot}l^{-1}$. The dominant species were 11 taxa including Pediastrum duplex, Scenedesmus quadricauda in green algae, Osillatoria limosa, Microcystis aeruginosa, Merisomorpedia sp., Phormidium sp. in blue-green algae, and Asterionella gracillima, Aulacoseira granulata, Fragilaria crotonensis, Stephanodiscus hantzschii f. tenuis, Synedra acus in diatoms. Asterionella gracillima and Stephanodiscus hantzschii f. tenuis were abundant at every station from winter to spring. Stephanodiscus hantzschii f. tenuis occupied the highest dominant ratio and standing crop. From summer to autumn, dominant species were Aulacoseira granulata at all stations and blue-green algae such as Osillatoria limosa, Microcystis aeruginosa, Merisomorpedia sp. at some stations. These 4 species were mostly present at the lower stations 4, 5, 6 and very few at the upper stations 1, 2, 3.

• ALGAE
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• v.19 no.3
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• pp.247-255
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• 2004

This study was to clarify the variations in a marine ecosystem through examining the species composition of phytoplankton in the coastal water of Baegyado Island during winter. Water temperature, salinity, SS, NH$_4$-N, NO$_2$-N, NO$_3$-N and SiO$_2$-Si were significantly different and in inverse proportion to the chlorophyll a and species number according to stations and water depth. The total number of species was 88, composed of 94% Bacillariophyceae, 3.4% Chrysophyceae, 2.2% Dinophyceae and 1.1% Euglenophyceae. The dominant species were Rhizosolenia setigera, Skeletonema costatum and Stephanopyxis palmeriana. The maximum of standing crops was $5,450cells{\cdot}ml^(-1)$, while the minimum was $1,700cells{\cdot}ml^(-1)$. The coastal water was influenced with two water bodies which had characteristics of low water temperature - low salinity and high water temperature - high salinity.

• Journal of Plant Biology
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• v.14 no.3
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• pp.36-42
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• 1971

The effects of irregular burning of vegetation by man were studied in relation to composition and productivity in a non-agricultural montane grassland in the Chongsun area, Kangwon-Do, Korea. The floristic composition in all study area includes 38 species. Three of the stations are dominated by Arundinella hirta and one is dominated by Miscanthus sinensis. The standing crop of the first station, which was fired in early spring, 1970, was 358.7g/$m^2$ to 497.5g/$m^2$; that of the second station, fired in late 1969 was 351. 5g/$m^2$; the third station, fired sometime in 1968, had a standing crop of 314.5g/$m^2$ to 397.1/$m^2$; the fourth station, having had no recent fires, had a standing crop of 370.0g/$m^2$ to 448.0g/$m^2$. The daily productivity shows a maximum of 6.03g/$m^2$ in the first station, and a minimum of 0.85g/$m^2$ in the fourth station. The productivity of grassland in the study area is at a maximum during July and August because of much precipitation, and decreases rapidly in the months to follow. The productive structure of the first and fourth stations is shown in Fig. 2 and 3. At the first station the maximum height attained by the plants was 180cm. In the height range of 50cm to 100cm there was a maximum of assimilative organs (5.6g/0.25$m^2$$\times$10cm), while in the height range below 50cm there was a maximum of non-assimilative organs (13.0g/0.25$m^2$$\times$10cm). At the fourth station, which has not been fired recently, the maximum height reached by the plants was commonly below 100cm. The assimilative organs showed a maximum abundance in the height range of 40cm to 50cm (4.5g/0.25$m^2$$\times$10cm). while the non-assimilative organs showed their greated abundance in the height range below 10cm (6.0g/0.25$m^2$$\times$10cm). There was a direct relationship between daily productivity and organic matter, available phosphorous, exchangeable calcium and potassium. It appears that the nutrients provided by the ash created in the firing of the study can be an important factor in the productivity of these grasslands.

• Korean Journal of Weed Science
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• v.16 no.1
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• pp.36-41
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• 1996

The experiments were conducted to identify the herbicidal effect of 2,4-D{ (2,4-dichlorophenoxy) acetic acid}, 2,4-D ethylester {ethyl 2,4- dichlorophenoxy acetate} and bentazon{3- isopropyl-1H-2,1,3- benzothiazin- 4-(3H)one 2,2-dioxide} on Sagittaria trifolia. Both 2,4-D and 2,4-D ethylester could completely control S. trifolia when applied before 80 days after transplanting of the tubers (DAT), but the weeding effect by bentazone decreased when applied after 60 DAT. 2,4-D and 2,4-D ethylester were effectively translocated from the treated parts to growing point. They killed S. trifolia completely when applied at 80 DAT under 3cm standing water depths, but the controlling effect by bentazone decreased at deeper than 1cm standing water depth. Formation of S. trifolia tuber was effectively suppressed with 2,4-D at 7g ai/10a and 2,4-D ethylester at 6g ai/10a when applied 60 DAT.

• Ocean and Polar Research
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• v.27 no.1
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• pp.15-24
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• 2005

In order to investigate the structures and dynamics of phytoplankton communities, each physicochemical environmental factor, species composition, standing crop, and dominant species were examined in the marine ranching ground of Tongyeong coastal waters from April to October, 2000. During the studies, mean water temperature and salinity were $18.8^{\circ}C$ and 33.1 psu, respectively. DO, SS and transparency varied from 5.43 to 11.39 mg/l, 14.6 to 32.4mg/l and 3.5 to 9.0m, respectively. Light intensities varied from 0.02 to $966{\mu}E/m^2/s$, which decreased with depth. $NH_4-N,\;NO_3-N,\;NO_2-N,\;PO_4-P,\;and\;SiO_2-Si$ were fluctuated from 0.059 to 0.332 mg/l, 0.040 to 0.800 mg/l, 0.001 to 0.468 mg/l, 2.3 to $143.0{\mu}g/l$, and 0.007 to 0.600 mg/l, respectively. chlorophyll a concentrations were fluctuated from 0.7 to $8.9{\mu}g/l$. Among 130 taxa of phytoplankton communities observed. diatoms occupied more than 81.54% of the total species, and the others were dinoflagellates and silicoflagellates. Phytoplankton standing crops ranged from $4.6{\times}10^4\;to\;2.6{\times}10^6cells/l$. In October, the standing crops were at bloom level showing more than $10^6cells/lat$ all stations. Dominant species changed by month and station. Leptocylindrus danicus occupied 59.84% in April and 22.03% in June. Pseudo-nitzschia pungens in August and Chaetoceros socialis and Skeletonema costatum in October were predominant species. In order to investigate factors influencing the total phytoplankton standing crops the correlations between the standing crops of diatoms, dinoflagellates, all phytoplanktons occurred and environmental factors were calculated using a multiple regression analysis. The coefficient of determination $(R^2)$ for total standing crops was 0.63 which explained 63% of variance and that of $R^2$ for diatom was 0.82. In statistical analysis, the results showed that the environmental factors influencing the size of the communities were predominantly water temperature, salinity and silicate.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.223-231
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• 2013

This study investigated the physio-chemical water quality and the standing crop of the phytoplankton of Dong-stream in Jeollanam-do from May 2010 to Feb 2011. The indicators and the dominant species of phytoplankton were also measured to investigate the water quality of estuary. Nutrients turned out to be eutrophic to hypertrophic in most sites with total nitrogen ranging 1.023~10.743 mg/L and total phosphorous ranging 0.0182~1.6848 mg/L. The site D6 had the highest BOD ranging 0.6~7.5 mg/L. Total of 205 taxa appeared within the research period, Bacillariophyceae being the highest number of taxa. The appeared species were taxa resistant to pollution including Navicula pupula, N. subminuscula, Nitzschia amphibia and N. palea. The downstream is thought to be greatly affected by the ocean water since marine and estuary phytoplankton such as Skeletonema costatum, Coscinodiscus radiatus, Bacteriastrum delicatulum and Eucampia biconcave appeared. Diatom appeared mainly as dominant species including Cymbella minuta, Melosira varians, Gomphonema parvulum, Stephanodiscus hantzschii. As for Stephanodiscus hantzschii, it dominates during fall and winter when the water temperature drops. Diatom showed 50% or higher dominant rate in all seasons at most sites. Most sites turned out to be eutrophic based on the standing crop of cells and chlorophyll a concentration. Total of 15 polluted water indicating taxa including Oscillatoria limosa appeared. From this result, the Dong-stream was considered to be in the eutrophication.

• 한국해양학회지
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• v.20 no.3
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• pp.37-54
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• 1985

A description of the "phytohydrography" in the southwestern waters of the East Sea is given from concurrent measurement of temperature, chlorophyll-a, nutrients, and phytoplankton and also from the calculated primary production during the two cruises in May and October, 1984. Past history of water mass is relatively well reflected in the distribution of phytoplankton species, but such a reflection is rarely shown in the distribution of physical and chemical parameters in general. Upper layer of the waters around Ul-gi and Gampo is typically characterized by the high chlorophyll-a, high primary production, and low nanofraction ratio due to the continuing supply of nutrients from the nutrient-rich cold water underneath. Water of Tsushima current shows poor standing crop in terms of cell numbers and chlorophyll-a concentrations, extremely high nanofraction ratio, and very low primary production. The overwhelming importance of the nanofraction is confirmed in phytoplankton cell numbers, chlorophyll-a concentration, and possibly enough in primary production. This emphasizes the exceptionally strong inflow of warm water into the study area from south among all the waters around the whole Korean peninsula.

• ALGAE
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• v.17 no.2
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• pp.95-104
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• 2002

Population dynamics of Anabaena and the anatoxin-a concentration were monitored with physicochemical parameters at 3 sites in the lower Naktong River from May to September in 2000. Total 4 species of Anabaena (A. flosaquae, A. smithii, A. ucrainica and A. mucosa) were identified with morphological characterisitcs. Anabaena flos-aquae was most abundant among the populations. The standing crop of Anabaena ranged from 10 to 11,220 cells · $ml^{-1}$ and biomass of Anabaena more 1,000 cells · $ml^{-1}$ was obseved once at St. Mulgeum and St. Seonam, twice at St. Hagueon out of total 9 samplings. There were not significant correlations between the standing crop of Anabaena and other physicochemical parameters such as temperature, nitrate, total nitrogen, phosphate, total phophorus and N/P ratios. The frequency of trichomes with akinetes was low and ranged from 0 to 4% in the total Anabaena population and A. smithii showed highest frequency of 2.8% among all species. The population at St. Seonam showed highest frequency of 1.4% among all sampling sties. The population in September showed the highest frequency of 3.0% among all sampling period. The frequency of trichomes with heterocysts was low and ranged from 1 to 87% inthe total Anabaena population and A. smithii showed highest frequency of 55.1% among all species. The population at St. Mulgeum showed highest frequency of 17.6% among all sampling sites. The population in August showed the highest frequency of 21.4% among all sampling period. The frequency of trichomes with akinetes and/or heterocysts was not related to all the physicochemical parameters of temperature, nitrate, total nitrogen, phosphate, total phosphorus and N/P ratios. The anatoxin-a concentations were determined in algal materials dominated by Microcystis and Anabaena from June though August by derivatization using 7-fluoro-4-nitro-2, 1,3-benzoxadiazole (NBD-F) and HPLC analysis with fluorimetric detection. All the concentrations were below the detection limit of 0.1 ㎍ · $l^{-1}$ in the present study.

• 한국해양학회지
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• v.13 no.2
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• pp.31-41
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• 1978

The planktonic algal communities of the Han River with a particular emphasis on water pollution was studied over a twelve month of period. Results of observing many algal communities from 7 stations of the Han River have shown that these communities are generally composed of many species, most of which have relatively small populations with a few exceptional dominant species. The distribution of the total standing crop of phytoplankton in the studid area is characteristic, summer in the polluted zone. Diversity indices of all samples were computed and have shown that the H values of 7 stations are relatively low. However, a detailed examination of these H values reveals that the seasonal fluctuations of the species diversity remarkably coincide with those fo phytoplankton standing crop.No reduction in the species diversity at stations 4, 5, 6, and 7 where the water is heavily polluted indicates that a great number of species capable of invading stations, 4, 5, and 6 from the various tributaries, and the station 7 from the contaminated with sea water are probably more important in the functional changes of the communities than the size of sampling area. It is evident that the diversity index in a lotic environment does not indicate water quality as far as phytoplankton communities are concerned.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.6
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• pp.541-549
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• 1992

Lodging and rainfalls during ripening periods and ripening patterns were studied by the different maturing varieties and different seeding dates in labour saving-direct seeding cultivation of rice. Period of emergency in earlier seeding plot was longer than later seeding plot and standing seedlings per unit area and rate of standing seedlings were more and high by the later seeding date. Number of panicles per unit area was decreased by the later seeding dates. On the other hand, the rate of effective tillers was lowest at later seeding plot. Days from seeding to flowering were shortened by the later seeding dates due to the increase of daily growth temperature and reduce of day length. There was much rainfalls during ripening period of early maturing varietal group, however not much rainfalls during ripening period of medium and late maturing varietal groups. The degree of lodging at field was severer by the amount of rainfalls during ripening period. Earlier seeding plots and earlier maturing varietal groups. of used varieties were revealed heavier lodging compared to later seeding plots and later maturing varietal groups. Yield and yield related characteristics were high and good by the earlier seeding dates, especially ripening rate was clear.