• Journal of Marine Life Science
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• v.4 no.2
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• pp.81-85
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• 2019

This study was carried out to observe the changes of seaweed community in artificial reefs installed in September, 2016 in Namae-ri, Yangyang-gun, and Seokbyeong-ri, Pohangsi, Korea. Field surveys were conducted by SCUBA diving once a season in February, May, August, and November of 2017, and quantitative survey and qualitative survey were carried out in parallel. In this study, a total of 94 species, including 11 green algae, 15 brown algae and 68 red algae were appeared. 66 species (8 green algae, 9 brown algae, 49 red algae) and 65 species (7 green algae, 9 brown algae, 49 red algae) were collected and identified in Yangyang and Pohang. In dominant species, Yangyang was dominant species of Saccharina japonica and subdominant species of Ulva australis. Pohang dominated in order of Colpomenia sinuosa and Gelidium elegans. In both coastal areas, Ulva spp., Colpomenia sinuosa were grown at the early stage of reforestation, and perennial seaweeds such as Saccharina japonica, Ecklonia cava and Gelidium elegans were grown. In order to clarify the clustering relation through flora change, it is necessary to monitor the transition process until the seaweed community is stabilized by observing the long-term change through continuous monitoring.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.305-309
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• 1983

To know the effect of desaltation in the reclaimed tidal fields on the succession of vegetation and on the root hair formation of paddy rice, reclaimed fields in Kang Hwa Island, Nam-Yang Bay and Ke-Hwa Island were investigated during summer crop season in 1982. The obtained results can be summarized as followings. l) In the highly salty and water logged areas of reclaimed tidal fields, the first dominating species of higher plant were observed to be Salicornia herbacea L. and Suaeda japonica Makino. With the continued desaltation, Chemopodium virgatum Thumb. occurred in the vegetation. After this transition, the dominating species were composed of Scirpus maitimus L. and Phragmites communis Trin. At the S. maitimus and P. communis dominating salinity level, rice cultivation was safe from the salt damage. 2) In the water logged area, Artemisia capillaria Thunb. and Aster tripolium L. took the place of dominating species after S. herbacea and S. japonica. At this salinity level, graminaceous weeds began to immigrate. 3) In dry areas, Suaeda asparagoides Makino and Suaeda maritima were the first appearing dominant species. Atriplex subcordata Kitakawa was also observed in sucy dry areas, but colony formation was not observed. 4) Plants immigrated slowly into dry areas from the already vegetated water logged areas with the continuation of desaltation. 5) The high soil salinity level affected the root hair formation of rice by reducing both the rate of root hair formation and the length of root hairs.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.30-44
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• 2001

In this study limnological characteristics of Lake Juam was surveyed from June 1993 to May 1994 in order to provides important information regarding water resources. Secchi disc transparency, epilimnetic chlorophyll a (chi-a), total nitrogen (TN), total phosphorus (TP) concentration and primary productivity were in the range of $2.0{\sim}4.5\;m$, $0.9{\sim}13.6\;mgChl/m^3$, 0.78$\{sim}$2.32 mgN/l, $11{\sim}56\;mgP/m^3$, $270{\sim}2.160\;mgCm^{-2}\;day^{-1}$, respectively. On the basis of TP, Chl-a and Secchi disc depth, the trophic state of Lake Juam can be classied as mesotrophic lake. The phosphorus inputs from non-point sources are concentrated in heavy rain episodes during the monsoon season. As a result, phosphorus concentration are higher in summer than in winter. TP loading from the watershed were estimated to be $0.9\;gPm^{-2}yr^{-1}$, which correspond to a boundary of the critical loading ($1.0\;gPm^{-2}yr^{-1}$) for eutrophication. From the results of the algal assay, both phosphous and nitrogen act as limiting nutrients in algal growth. The seasonal succession of phytoplankton community structure in Lake Juam was similar to that observed in other temperate lakes. Diatoms (Asterionella formosa and Aulacoseira granulate var. angustissima)fujacofeira BraHuJafa uar. aHgusHrsiaia) weredominant in spring and winter, cyanobacteria) were dominant in warm season. The organic carbon, nitrogen and phosphorus content of lake sediment were $9.5{\sim}14.0\;mgC/g$, $1.01{\sim}1.82\;mgN/g$ and $0.51{\sim}0.65\;mgP/g$, respectively. The allochthonous organic carbon loading from the watershed and autochthonous organic carbon loading by primary production of phytoplankton were determined to be 1,122 tC/yr and 6,718 tC/yr, respectively. To prevent eutrophication of Lake Juam, nutrient management of watershed should be focus on reduction of fertilizer application, proper treatment of manure, and conservation of topsoil as well as point source.

• Korean Journal of Weed Science
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• v.5 no.1
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• pp.73-84
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• 1985

25 tank-mixed combinations between Haloxyfop-methyl at 0, 0.05, 0.1, 0.15 and 0.2 kg ae/ha and Acifluorfen at 0, 0.082, 0.163, 0.245 and 0.326 kg ai/ha were applicated at post-emergence on the late-season cropped soybean(Glycine max) fields predominated by grasses and assessed on the weeding efficacy. A most abundant weed species on the experimented fields were found at September (25 species). The broadleaved weed species and sedges were successively and proportionately emerged by the control rate of grass species. From the mono-treatment of each herbicide, Haloxyfop-methyl was recognized as a highly selective one between grasses and soybean, and Acifluorfen between broadleaf weeds and soybean, respectively. By combined application with both herbicides a synergistic weeding efficacy was detected on total weed species, however antagonistic or additive on each weed groups. Among other traits of soybean, stem dry weight was influenced by weed competitions during October, number of pods per plant during August and seed yields during whole periods. For most effective and reasonable weeding, no less than 0.4 kg ai/ha of each herbicides should be applicated in combinations.

• Korean Journal of Ecology and Environment
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• v.47 no.2
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• pp.116-126
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• 2014

To evaluate the relationship between dynamics of Cyanobacterial bloom and rainfalls, a monthly monitoring of water quality and phytoplankton from the three serial lakes (Lake Ui-am, Lake Chung-pyeong and Lake Pal-dang) in the North Han River System were examined 12 times from May 2012 to March 2013. A dense bloom of cyanobacterium Anabaena spp., was occurred over three lakes in the summer season of 2012. In Lake Ui-am, the Anabaena population appeared in June, showed a peak in July (43,850 cells $mL^{-1}$) and disappeared in November 2012. In Lake Chung-pyeong and Lake Pal-dang, Anabaena population commonly appeared in July, showed the peaks (31,648 cells $mL^{-1}$ and 7,136 cells $mL^{-1}$, respectively) in August, and entirely disappeared in September 2012. Over the three lakes, the phytoplankton community was commonly dominated by diatoms before Monsoon, cyanobacteria during Monsoon, and diatoms after Monsoon, respectively, indicating a Monsoon-dependent succession. A correlation analysis revealed that dynamics of Anabaena population was strongly related with rainfall (r=0.72, r=0.83, r=0.88, P<0.01 for three lakes), and partly with nutrients, inflow and outflow of lakes. Therefore, this study indicates that the outbreak and destruction of Anabaena bloom in North Han River System between 2012 and 2013 was impacted by rainfalls. However, a high density of cyanobacteria in Lake Ui-am remained after Monsoon, and thus, may paroduce bad-order and toxins from phytoplankton.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.147-158
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• 2007

To clarify the bloom pattern and species succession in phytoplankton community, the population dynamics with the determination of physico-chemical factors have been studies in Masan Bay, the south sea of Korea, for the periods November 2003-October 2004. Concentration of $NH_4-N$ was always higher than that of $NO_3-N$, which was similar level as compared to other costal areas. $PO_4-P$ concentration was lower than those in other coastal areas but similar to oligotrophic environments. Thus, phosphate seems the limiting nutrient rather than nitrogen. $SiO_2-Si$ concentration was also low as compared to other costal areas. Si:P ratio was low from autumn to winter, suggesting silicate and/or phosphate limitation during this period. The cell density of phytoplankton was high in winter 2003 and early autumn 2004. The carbon biomass was high in winter 2003 and summer 2004. And chlorophyll-a concentration was high in late autumn 2003 and summer 2004. Among 78 species of phytoplankton found in the bay during the investigated period, dominant species were two diatoms of Cylindrotheca closterium, Skeletonema costatum, and three dinoflagellates of Heterocapsa triquetra, Prorocentrum minimum, P. triestinum, and one raphidophyte of Heterosigma akashiwo. P. minimum dominated from late autumn to winter, but it was replaced by H. triquetra in late winter. P. triestinum dominated from late spring to early summer. Simultaneously, H. akashiwo cell density steadily increased, and it became dominant with C. closterium in late summer. With decreasing of H. akashiwo and C. closterium, S. costatum became the most dominant species in autumn. The canonical analyses showed that total phytoplankton cell density related to diatom cell density and it was affected by temperature, and concentrations of $NO_3-N\;and\;PO_4-P$. The carbon bio-mass and $chlorophyll-{\alpha}$ concentration related to diatom- and dinoflagellate cell densities and these were affected by flagellate cell density, salinity, and concentrations of $SiO_2-Si\;and\;PO_4-P$. Last six years monitoring data in Masan city obtained from Korean Meteorological Agency indicates gradual increase in air temperature. And the precipitation decreased especially in spring season. The winter bloom found in 2003 may be caused by the increase in the temperature and this bloom subsequently induced the nutrients depletion, which continued until next spring probably due to no precipitation. Therefore, the spring bloom, which had been usually observed in the bay, might disappear in 2004.