• Journal of Environmental Impact Assessment
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• v.15 no.1
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• pp.35-43
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• 2006

The eutrophication in lakes is caused by the inflow of excessive nitrogen and phosphorus, which are not only pollutants to reduce the value of water resource but also nutrients for algae growth that debases water quality. Several methods have been used to judge the eutrophication grades of lakes, but the judgment results can be different with one another even under same coditions because each method is different in judgment items and their standards. A method for overcoming the problem with the judgment of eutrophication grades is, therefore, developed in this study with the application of fuzzy theory. This method allows decision makers to represent the uncertainties (differences) of results by the existing judgment methods and also incorporate associated uncertainties directly into the judgment process, so the judgment results can be made that are more realistic and consistent than those made without taking uncertainty in account.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.313-314
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• 2001

The palaemonid shrimp Exopazaemon modestus inhabits the freshwater of the Indo-West Pacific, Siberia, Manchuira, Korea, China, Taiwan (Holthuis, 1980) and is abundant in the fresh water areas of southwest of Korea. Palaemonid shrimps are adapted to a variety of habitats in freshwater, brackish and marine environments. They play important role in the ecosystem of fresh, brackish and marine waters, acting as predators feeding on algae, detritus, crustaceans and meiofauna (Bell and Coull, 1978) and in turn, as preys for fishes and other predators (Anderson, 1985). (omitted)

• Animal cells and systems
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• v.4 no.3
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• pp.201-214
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• 2000

Two quite different types of plant cells are analysed with regard to transduction of the gravity stimulus: (i) Unicellular rhizoids and protonemata of characean green algae; these are tube-like, tip-growing cells which respond to the direction of gravity. (ii) Columella cells located in the center of the root cap of higher plants; these cells (statocytes) perceive gravity. The two cell types contain heavy particles or organelles (sataoliths) which sediment in the field of gravity, thereby inducing the graviresponse. Both cell types were studied under microgravity conditions ($10^{-4}$/ g) in sounding rockets or spacelabs. From video microscopy of living Chara cells and different experiments with both cell types it was concluded that the position of statoliths depends on the balance of two forces, i.e. the gravitational force and the counteracting force mediated by actin microfilaments. The actomyosin system may be the missing link between the gravity-dependent movement of statoliths and the gravity receptor(s); it may also function as an amplifier.

• Environmental Engineering Research
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• v.15 no.1
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• pp.41-48
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• 2010

This paper describes the influence of nutrient salts eluted from the bottom of a closed water area where polluted sediment has been deposited by inflowing river water. The elution pattern was monitored at our experimental facility. Both the sediment pore water and water above the bottom were sampled using a dialyzer sampler (peeper). The pore water of the eutrophicated sediment contained a large amount of nutrient salts, and the effect of elution was confined to a limited area of the bottom surface. The nutrient concentration of the sediment pore water was closely related to both the water temperature and dissolved oxygen (DO) concentration. The eluted nutrients from the sediment provided a source for phytoplankton and algae growth. This experimental data indicated that the water quality of the surface was not directly connected to the eluted nutrient salts, while it was indirectly affected by the total ecosystem, including all the organisms within an area and their environment.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.1
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• pp.126-129
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• 2011

Vegetative morphological information of the red alga Neorhodomela larix (Turner) Masuda (Rhodomelaceae) is given. This species is characterized by thalli up to 15 cm high, brownish black in color, pericentral cells with transverse division, the first order subulate branches with determinate growth, numerous adventitious branches produced at axils and absence of vegetative trichoblasts. Particularly, N. larix is distinct from other Korean Neorhodomela species by the lack of vegetative trichoblasts, which seems to be caused by their delayed production until reproductive structures are formed. This is the first record of N. larix in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.79-85
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• 1981

As one of the fundamental studies for the breeding of marine algae, the effects of several plant hormones (IAA, Gibberellin, 2.4-D, NAA, Kinetin) on the growth of Porphyra-fronds, P. tenera Kjell. form tamatsuensis Miura, were investigated from January 21 to February 21 1981. The fronds used for the experiment were dissected out at $25mm^2$ size, and cultured in modified Provasoli's ESP medium supplemented with various concentrations of each plant growth regulators. The culture was kept under constant water temperature of $5^{\circ}C$ in 14 hrs. photoperiod and illuminated with 2,400 lux by fluorescent light. Based on the results of first experiment, the culture of fronds for the secondary experiment was carried out at $5^{\circ}C\;and\;10^{\circ}C$ in medium containing various levels of Kinetin from April 6 to 24, and compared the growth of two groups at each concentrations with each other, The results obtained are summarized as follows : (1) The best growth efficiencies were observed at 5.0mg/1 of each plant hormones except Gibberellin. Among them, the highest growth-rate was $312.5\%\;(345.3\%\;in\;frond\;size)$ in contrast with control at 5.0mg/1 of Kinetin, and was followed by $257.5\%\;(236.1\%)$ in 2.4-D,$166.7\%(147.6\%)$ in IAA and $141.7\%\;(167.7\%)$ in NAA, but that in Gibberellin was $247.9\%(241.9\%)$ at 10.0mg/l. (2) Especially, the fronds cultured at 5.0mg/1 of Kinetin were deep black-brown in colour, and had vivid, healthy chloroplasts in their all cells. On the contrary, the fronds cultured in other media were discoloured to light black-brown or green-drown, and almost all cells were vacuolated or shrunk gradually into death.(3) There was an obvious difference between the best growth-rates of the fronds cultured at 5.0mg/l of Kinetin at $5^{\circ}C$ and those at $10^{\circ}C$. The former was $366.7\%$, the latter $318.8\%$ but the difference was little at lower concentrations. (4) Many abnormal cells grown up to $25.0-27.5\mu$ in diameter were found among the marginal cells of fronds which showed the best growth in Kinetin, and the fronds wire $41.0-42.0\mu$ in thickness which was thicker by $10.0\mu$ or so than the others. (5) In two fronds at 1.0mg/1 of Kinetin cell-divisions were observed, which might developed into antheridium, but it was doubtful whether due to the efficiency of Kinetin.

• Journal of Aquaculture
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• v.11 no.1
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• pp.19-29
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• 1998

An 18-week growth trial was conducted in flow-through aquarium system to evaluate the practical dietary protein sources for juvenile abalone (Haliotis discus hannai). Three replicate groups of the abalone averaging 0.11g were fed one of ten diets containing casein, white fish meal (WFM), meat meal (MM), feather meal (FM), blood meal (BM), soybean meal (SM), corn gluten meal (CGM), cotton seed meal (CSM), Undaria powder (UP), or wheat flour (WF) as a dietary protein source. In addition, these dietary protein sources were cmpared with algae such as raw Undaria or dried Laminaria. Weight gain of abalone fed the diets containing casein, WFM, SM, CSM, or UP was significantly higher (P<0.05) than those of abalone fed other diets, and this value of abalone fed FM, BM, CGM, or algae was lower than other groups. Shell length, shell width, body wt./shell length ratio, and body wt./shell width ratio of abalone fed casein, WFM, SM, CSM, UP, and WF were also highe (P<0.05) than those of other groups. There were no significant difference (P>0.05) in moisture and protein contents of soft body among all diets. The data obtained in this study indicate that each of the casein, WFM, SM, CSM or UP is good dietary protein source for juvenile abalone.

• Research in Plant Disease
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• v.22 no.4
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• pp.257-263
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• 2016

Chlorella is known as chlorophyceae which can live autotrophically by photosynthesis, promote the growth of plants and suppress some plant diseases. However, a few researches in inhibition mechanism of plant diseases by chlorella have been carried out. In this study cucumber leaves pre-treated with Chlorella fusca suspension were investigated whether anthracnose by Colletotrichum orbiculare is suppressed or not. Furthermore, in order to illustrate how the algae can restrain the antracnose, the infection structures of C. orbiculare were observed on the cucumber leaves pre-treated with the algae. Consequently, appressorium formation rate was apparently reduced in the cucumber leaves pre-treated with C. fusca compared to untreated control one. Also, the numbers of conidia found at the inoculation sites were significantly reduced compared to untreated one. On the other hand, on the leaves pre-treated with $Benomyl^{(R)}$ appressorium formation were decreased remarkably and numbers of conidia were also reduced similar with those pre-treated with C. fusca. Based on these results, it was revealed that occurrence of anthracnose can be suppressed by C. fusca pre-treatment and suggested that biochmical or structural hinderance by C. fusca resulting in the decline of appressorium formation on the leave surfaces may play an important role in the disease suppression.

• Korean Journal of Environmental Agriculture
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• v.2 no.2
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• pp.108-113
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• 1983

There has been two kind of research fields in evaluating the ecotoxicity of chemicals The one is a bioassay and the other is an ecosystem analysis. The toxicants are transported into different biota, which have quite different environmental behaviour patterns and toxic properties. The effects of pesticides (butachlor, carbofuran, and tricyclazole) on periphyton community was studied by analyzing content of chlorophyll-a and autotrophic index (AI) that is a means of determining the trophic nature of the periphyton community. Results indicated that the content of chlorophyll-a was not influenced by the pesticides. The growth of algae was inhibited by sunshine period. And AI value is 43-2027: the large value indicates heterotrophic periphyton community, and was not affected by pesticides.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.93-98
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• 2008

We investigated the effect on the removal of BOD, SS, TN and TP and algal growth inhibition of Vegetated Artificial Floating Island (VAFI), by examining microorganism activity and nutrient uptake in the batch test of various conditions: (1) Blank (Control group), (2) VAFI of $0.25m^2$, (3) AFI of $0.25m^2$ which has no vegetation, (4) buoyant plate of $0.25m^2$, (5) buoyant plate of $0.25m^2$ with linear media. The proportion of BOD removal in the VAFI, AFI, buoyant plate and buoyant plate with media were 82.7, 80.8, 45.2% and 59.6% respectively. TN removal in the VAFI, AFI and buoyant plate with media were 51.2, 31.7% and 25.1% respectively. TP removal in the VAFI, AFI, buoyant plate and buoyant plate with media were 23.3, 16.7, 10.0% and 13.3% respectively. Chlorophyll-${\alpha}$ removal in the VAFI was 97.9%. The factors of chlorophyll-${\alpha}$ removal in the VAFI accounted for the shading effect of 35.1%, microorganisms activity of 61%, and plant root of 1.8%.