• Korean Journal of Environmental Biology
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• v.22
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• pp.54-62
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• 2004

We examined the impacts of anthyopogenic pollutant (benzo〔a〕pyrene) on the growth and photosynthesis of five marine phytoplankton species (Skeletonema costatum, Heterosigma akashiwo, Prorocentrum dentatum, P. minimum, Aknshiwo sanguinea), which are dominant in Korean coastal water. After the 72 h exposure to benzo〔a〕pyrene, the dramatic decrease in cell numbers was observed in the range of 1 to 10 $\mu\textrm{g}$ L$^{-1}$ for S. costatum, P. minimum, P. dentatum, whereas for A. sanguinea and H. akashiwo at the low concentrations 0.1 to 1 $\mu\textrm{g}$ L$^{-1}$ . Among the 5 phytoplankton species, the highest growth inhibition concentration ($IC_{50}$/) was 6.20 $\mu\textrm{g}$ L$^{-1}$ for P. minimum, followed by 2.14 $\mu\textrm{g}$ L$^{-1}$ for P. dentatum, 1.68 $\mu\textrm{g}$ L$^{-1}$ for S. costatum, 0.74 $\mu\textrm{g}$ L$^{-1}$ for H. akashiwo, 0.10 $\mu\textrm{g}$ L$^{-1}$ for A. sanguinea. The five species exposed to the low concentration of 1 $\mu\textrm{g}$ L$^{-1}$ were recovered after transferring to new media, but the species exposed to the high concentrations of 10 and 100 $\mu\textrm{g}$ L$^{-1}$ were not recovered, with the exception of P. minimum. Those results indicate that the thecate dinoflagellate P. minimum is most tolerant to the chemical and the athecate dinoflagellate A. sanguinea is not. Geneyally, the cell-specific photosynthetic capacity of H. akashiwo exposed to the low concentrations of 0.1 and 1 $\mu\textrm{g}$ L$^{-1}$ was higher than that of the cells in the control, whereas the cells exposed to the high concentrations of 5 and 10 $\mu\textrm{g}$ L$^{-1}$ showed the negligible photosynthetic level by the first few days of the experiment. In the case of the cells exposed to the concentration of 5 $\mu\textrm{g}$ L$^{-1}$ , after 12 days of the experiment the photosynthetic capacity was increased toward the end of the experiment. This indicates that H. akashiwo may utilize the benzo〔a〕pyrene as a carton source for its growth when exposed to low concentrations. Results suggest that anthropogenic pollutants such as benzo〔a〕pyrene may have significant influence on the succession of phytoplankton species composition and the primary production in coastal marine environments.

• Journal of Korean Society of Forest Science
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• v.52 no.1
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• pp.58-71
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• 1981

Thecodiplosis japonesis is sweeping the Pinus densiflora forests from south-west to north-east direction, destroying almost all the aged large trees as well as even the young ones. The front line of infestation is moving slowly but ceaselessly norhwards as a long bottle front. Estimation is that more than 40 percent of the area of P. densiflora forest has been damaged already, however some individuals could escapes from the damage and contribute to restore the site to the previous vegetation composition. When the stands were attacked by this insect, the drastic openings of the upper story of tree canopy formed by exclusively P. densiflora are usually resulted and some environmental factors such as light, temperature, litter accumulation, soil moisture and offers were naturally modified. With these changes after insect invasion, as the time passes, phytosociologic changes of the vegetation are gradually proceeding. If we select the forest according to four categories concerning the history of the insect outbreak, namely, non-attacked (healthy forest), recently damaged (the outbreak occured about 1-2 years ago), severely damaged (occured 5-6 years ago), damage prolonged (occured 10 years ago) and restored (occured about 20 years ago), any directional changes of vegetation composition could be traced these in line with four progressive stages. To elucidate these changes, three survey districts; (1) "Gongju" where the damage was severe and it was outbroken in 1977, (2) "Buyeo" where damage prolonged and (3) "Gochang" as restored, were set, (See Tab. 1). All these were located in the south temperate forest zone which was delimited mainly due to the temporature factor and generally accepted without any opposition at present. In view of temperature, the amount and distribution of precipitation and various soil factor, the overall homogeneity of environmental conditions between survey districts might be accepted. However this did not mean that small changes of edaphic and topographic conditions and microclimates can induce any alteration of vegetation patterns. Again four survey plots were set in each district and inter plot distance was 3 to 4 km. And again four subplots were set within a survey plot. The size of a subplot was $10m{\times}10m$ for woody vegetation and $5m{\times}5m$ for ground cover vegetation which was less than 2 m high. The nested quadrat method was adopted. In sampling survey plots, the followings were taken into account: (1) Natural growth having more than 80 percent of crown density of upper canopy and more than 5 hectares of area. (2) Was not affected by both natural and artificial disturbances such as fire and thinning operation for the past three decades. (3) Lower than 500 m of altitude (4) Less than 20 degrees of slope, and (5) Northerly sited aspect. An intensive vegetation survey was undertaken during the summer of 1980. The vegetation was devided into 3 categories for sampling; the upper layer (dominated mainly by the pine trees), the middle layer composed by oak species and other broad-leaved trees as well as the pine, and the ground layer or the lower layer (shrubby form of woody plants). In this study our survey was concentrated on woody species only. For the vegetation analysis, calculated were values of intensity, frequency, covers, relative importance, species diversity, dominance and similarity and dissimilasity index when importance values were calculated, different relative weights as score were arbitrarily given to each layer, i.e., 3 points for the upper layer, 2 for the middle layer and 1 for the ground layer. Then the formula becomes as follows; $$R.I.V.=\frac{3(IV\;upper\;L.)+2(IV.\;middle\;L.)+1(IV.\;ground\;L.)}{6}$$ The values of Similarity Index were calculated on the basis of the Relative Importance Value of trees (sum of relative density, frequency and cover). The formula used is; $$S.I.=\frac{2C}{S_1+S_2}{\times}100=\frac{2C}{100+100}{\times}100=C(%)$$ Where: C = The sum of the lower of the two quantitative values for species shared by the two communities. $S_1$ = The sum of all values for the first community. $S_2$ = The sum of all values for the second community. In Tab. 3, the species composition of each plot by layer and by district is presented. Without exception, the species formed the upper layer of stands was Pinus densiflora. As seen from the table, the relative cover (%), density (number of tree per $500m^2$), the range of height and diameter at brest height and cone bearing tendency were given. For the middle layer, Quercus spp. (Q. aliena, serrata, mongolica, accutissina and variabilis) and Pinus densiflora were dominating ones. Genus Rhodedendron and Lespedeza were abundant in ground vegetation, but some oaks were involved also. (1) Gongju district The total of woody species appeared in this district was 26 and relative importance value of Pinus densiflora for the upper layer was 79.1%, but in the middle layer, the R.I.V. for Quercus acctissima, Pinus densiflora, and Quercus aliena, were 22.8%, 18.7% and 10.0%, respectively, and in ground vegetation Q. mongolica 17.0%, Q. serrata 16.8% Corylus heterophylla 11.8%, and Q. dentata 11.3% in order. (2) Buyeo district. The number of species enumerated in this district was 36 and the R.I.V. of Pinus densiflora for the uppper layer was 100%. In the middle layer, the R.I.V. of Q. variabilis and Q. serrata were 8.6% and 8.5% respectively. In the ground vegetative 24 species were counted which had no more than 5% of R.I.V. The mean R.I.V. of P.densiflora ( totaling three layers ) and averaging four plots was 57.7% in contrast to 46.9% for Gongju district. (3) Gochang-district The total number of woody species was 23 and the mean R.I.V. of Pinus densiflora was 66.0% showing greater value than those for two former districts. The next high value was 6.5% for Q. serrata. As the time passes since insect outbreak, the mean R.I.V. of P. densiflora increased as the following order, 46.9%, 57.7% and 66%. This implies that P. densiflora was getting back to its original dominat state again. The pooled importance of Genus Quercus was decreasing with the increase of that for Pinus densiflora. This trend was contradict to the facts which were surveyed at Kyonggi-do area (the central temperate forest zone) reported previously (Yim et al, 1980). Among Genus Quercus, Quercus acutissina, warm-loving species, was more abundant in the southern temperature zone to which the present research is concerned than the central temperate zone. But vice-versa was true with Q. mongolica, a cold-loving one. The species which are not common between the present survey and the previous report are Corpinus cordata, Beltala davurica, Wisturia floribunda, Weigela subsessilis, Gleditsia japonica var. koraiensis, Acer pseudosieboldianum, Euonymus japonica var. macrophylla, Ribes mandshuricum, Pyrus calleryana var. faruiei, Tilia amurensis and Pyrus pyrifolia. In Figure 4 and Table 5, Maximum species diversity (maximum H'), Species diversity (H') and Eveness (J') were presented. The Similarity indices between districts were shown in Tab. 5. Seeing Fig. 6, showing two-dimensional ordination of polts on the basis of X and Y coordinates, Ai plots aggregate at the left site, Bi plots at lower site, and Ci plots at upper-right site. The increasing and decreasing patterns as to Relative Density and Relative Importance Value by genus or species were given in Fig. 7. Some of the patterns presented here are not consistent with the previously reported ones (Yim, et al, 1980). The present authors would like to attribute this fact that two distinct types of the insect attack, one is the short war type occuring in the south temperate forest zone, which means that insect attack went for a few years only, the other one is a long-drawn was type observed at the temperate forest zone in which the insect damage went on continuously for several years. These different behaviours of infestation might have resulted the different ways of vegetational change. Analysing the similarity indices between districts, the very convincing results come out that the value of dissimilarity index between A and B was 30%, 27% between B and C and 35% between A and C (Table 6). The range of similarity index was obtained from the calculation of every possible combinations of plots between two districts. Longer time isolation between communities has brought the higher value of dissimilarity index. The main components of ground vegetation, 10 to 20 years after insect outbreak, become to be consisted of mainly Genus Lespedeza and Rhododendron. Genus Quercus which relate to the top dorminant state for a while after insect attack was giving its place to Pinus densiflora. It was implied that, provided that the soil fertility, soil moisture and soil depth were good enough, Genus Quercuss had never been so easily taken ever by the resistant speeies like Pinus densiflora which forms the edaphic climax at vast areas of forest land. Usually they refer Quercus to the representative component of the undisturbed natural forest in the central part of this country.

• Korean Journal of Environment and Ecology
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• v.18 no.1
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• pp.75-91
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• 2004

Biodiversity and seasonal community composition of benthic macroinvertebrates were studied from Upo wetlands in Gyeongsangnam-do, Korea, comprising Upo (4 sites), Mokpo (2 sites), Sajipo (1 site), Jjokjibeol (1 site), Yeobeol (1 site), and Topyeongcheon (2 sites) areas from October 2002 to August 2003. As a result, it was known that Upo wetlands retained relatively well-preserved littoral zones which may provide good habitats for benthic macroinvertebrates; however, frequent disturbances of littoral zones caused by flood were the major factor affecting on the survival and distribution of benthic macroinvertebrates in the areas. During the study period, a total of 135 species of benthic macroinvertebrates in 10 genera, 59 families, 16 orders, 7 classes, and 3 phyla were collected those of which are the highest degree of diversity of the taxa ever known in Korean wetlands: aquatic insects 103 spp. (Diptera 27 spp., Odonata 24 spp., Coleoptera 19 spp., Hemiptera 16 spp., Ephemeroptera 9 spp., Trichoptera 7 spp., and Collembola 1 sp.), Crustacea 2 spp., Mollusca 19 spp. (Gastropoda 12 spp. and Bivalvia 7 spp.), and Annelids 11 spp. (Oligocaeta 1 sp. and Hirudinea 10 spp.). Sajipo (St.G) and Jjokjibeol (St.H) areas yielded relatively larger numbers of species, 54 spp. and 53 spp., respectively, while more than 40 species occurred at most other sites. Based on quantitative sampling (0.5m${\times}$2m), aquatic insects (88.0％), particularly chironomids in Diptera (61.0％), occupied major proportion of the total individuals of benthic macroinvertebrates, while Mollusca (5.3％), Annelida (3.5％), and Crustacea (3.2％) occupied minor proportions. In standing water areas, diverse groups of benthic macroinvertebrates such as chironomids, demselflies, aquatic bugs, aquatic beetles, crustaceans, and gastropods were dominant in terms of individual number; in the running water areas, on the other hand, chironomids and baetid mayflies were dominant. However, gastropods, i.e. viviparids, were the dominant group of benthic macroinvertebrates in most study areas in terms of biomass. Dominance indices were 0.22-0.51 (mean$\pm$sd 0.42$\pm$0.09) in autumn, 0.31-0.96 (0.02$\pm$0.23) in winter, and 0.30-0.89 (0.57$\pm$0.18) in summer; diversity indices were 3.50-4.26 (3.80$\pm$0.24) in autumn,1.55-4.50 (3.10$\pm$1.01) in winter, and 1.35-3.77 (2.55$\pm$0.09) in summer. Highly movable or true aquatic benthic macroinvertebyates such as aquatic bugs, aquatic beetles, and gastropods recovered earlier after flood. In the study sites of Upo wetlands, Upo and Sajipo areas showed relatively higher values of average diversity index which may indicate a good habitat condition for benthic macroinvertebrates.

• Korean Journal of Ecology and Environment
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• v.44 no.3
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• pp.303-313
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• 2011

Field observations and culture experiments have been carried out during the rainy season (on the 6th, 8th and 27th July 2009) to examine changes in the primary productivity and associated plant pigments in the estuary of the Seom-jin River. Primary productivity was determined at four sampling stations along the salinity gradient. On 6th July (before heavy rain) primary productivity ranged from 689~1,169 mgC $m^{-2}$ $d^{-1}$. On the 8th, just after more than 216.5 mm of precipitation, euphotic layers at all stations were reduced to very shallow water because of the high concentration of suspended solids in the water. This resulted in dramatically decreased primary productivity down to as low as 12~32 mg C $m^{-2}$ $d^{-1}$. However, after the rain, primary productivity on the 27th ranged from 266~999 mgC $m^{-2}$ $d^{-1}$, demonstrating a fast recovery in the upper stream water to similar productivity levels to those before the rainy season. Concentration of fucoxanthin in the water was highest on the 6th July. Before the rain, concentration of the zeaxanthin, increased as the salinity decreased. Immediately after the heavy rain, the Chl b (Chlorophytes) concentration was higher at all sites than before the rainy season. The concentration of fucoxanthin decreased after the heavy rain. At the downstream site, peridinin (Dinoflagellates) were found. During the rainy season, the diatoms contributed to the primary productivity at all sites. However, after the rainy season, Chl b (Chlorophytes) and Peridinin (Dinoflagellates) increased, demonstrating the enhanced contribution of those species in addition to diatoms.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.3
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• pp.154-162
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• 2011

Seawater quality was investigated each month at 30 stations near Tongyeong, South Korea, to provide data for the effective use of coastal fisheries and the reduction of economic damage to marine products. Water temperature was lowest in January and highest at the end of August. Neither extremely low water temperature below $4^{\circ}C$ nor fish damage caused by low water temperature was observed. Salinity ranged from 24.04 to 34.39 psu in the surface layer and from 29.92 to 34.39 psu in the bottom layer. The minimum salinity, attributable to rainfall events, was observed in July; salinity increased to high of about 34 psu in November. Low dissolved oxygen (DO), below 4 mg/L, was observed at Wenmun and Buksin Bays during May to October. Concentrations of $NO_2$-N, $NO_3$-N, and $PO_4$-P were low from March to September and high from October to February. Transparency was 6 m on average and was high in Wenmun Bay. Chemical oxygen demand (COD) and chlorophyll a (Chl. a) were high during summer, when the water temperature was high. With cluster analysis based on environment factors related to water quality, the study area could be divided into three main sea areas: Buksin Bay, coastal seawater, and offshore seawater. Buksin Bay was characterized by low salinity, high DO and Chl. a, and high transparency in the surface layer and by low DO and high $NH_4$-N in the bottom layer. Offshore seawater had high salinity and $NO_3$-N and low Chl. a concentration. In summer season that oyster need lots of phytoplankton, $NO_3$-N and Chl. a concentrations at this study area were low compare to Gwangy-ang and Gamak Bays. In winter, a sea squirt swallow much more than other season, the Chl. a concentrations were also low than Gwangyang and Gamak Bays.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.32-38
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• 2016

The purpose of this study is to investigate the effects of the natural river conservation work and to find remedies for them, targeting Jangsu-cheon with high frequency of use by citizens among the rivers in Incheon Metroplitan City, Korea; for this, this study conducted investigations and analyses of Jangsu-cheon completed in December, 2008. As a result of investigating 3 spots for the water system of Jangsu-cheon over a total of 3 years (2009, 2010, 2014), it was found that benthic macro-invertebrates of a total of 3 phyla, 5 classes, 11 orders, 26 families, 56 species, and 980 specimens were distributed there. When they were analyzed by year, 18 families and 30 species in 2009, right after the natural river conservation work, and 22 families and 37 species in 2010, 2 years after the work, were found, with 7 species increasing in number; after that, as a result of the investigation in 2014, 22 families and 38 species were found, which tells the river has entered the stabilization stage since the recovery in 2010.Therefore, this study could identify: the water environment of the river was improved due to the natural river conservation work for Jangsu-cheon; in addition, Jangsu-cheon showed good ecological environment due to the continuous maintenance of the good wetlands in Incheon Grand Park in the upper area of the river; and the natural river conservation work of Jangsu-cheon created positive effects.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.389-397
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• 2015

Dongchun, one of the representative streams in urban area, is a downstream that is connected to Hogyechun, Bujeonchun, Jeonpochun, Danggamchun, and Gayachun as its upstream. Hogyechun has been mostly covered with concrete structures for decades, causing sewage pollution from the upstream, overflow of the downstream region and other serious pollution that gave rise to many civil complaints from the residents nearby. In this study, we analyzed 3 stations, including control station for water quality and malodor changes of Hogyechun after applying the microbial augmentation (BM-2) for a few months including the rainy season. Amounts (g/h) of DO in the middle site (Middle) and the downstream site (Borim) increased by 1.7 times compared with the upstream site (Chuhae) after augmentation for about 2 months. Amounts (g/h) of COD and $NO_3{^-}N$ decreased by 2 and 1.7 times, respectively, in the middle and downstream sites while SS increased by 7.5 and 22 times in the middle and downstream sites, respectively. Moreover, odor removal efficiencies at the middle and downstream sites were 65% and 19%, respectively, indicating the microbial activity in reduction of malodor in the polluted stream. The dominant microbial species of the sampling sites were Hydrogenophaga caeni, Sphaerotilus natans, Acidovorax radicis, Acidovorax delafieldii, and Cloacibacterium rupense. Densities of the two species Sphaerotilus natans and Acidovorax delafieldii were significantly increased in the middle site after augmentation which possessed potential odor removal and denitrification activity, respectively. Potential pathogens (e.g., Arcobacter cryaerophilus) were also removed from the middle site after the implementation.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.235-241
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• 2003

The effect of ultraviolet (UV) radiation on the characteristics of algae-derived dissolved organic matter (DOM) was examined by comparing the biodegradability and DOM fraction distribution of algal DOM before and after UV exposure. Algal DOM from two axenic cultures of Microcystis aeruginosa and Oscillatoria agardhii were irradiated for 24 h at a UV intensity of 42 W/$m^2$. A complete degradation of algal DOM during the UV exposure did not occur, remaining at constant concentrations of dissolved organic carbon(DOC). After UV exposure, however, microbial degradations were reduced by 17% in M. aeruginosa and 53% in O. agardhii, respectively, and decomposition rates also were two times lower in UV exposed algal DOM. In addition, the chemical compositions of algal DOM altered substantially after UV radiation exposure. The proportions of hydrophilic bases (HiB; protein-like DOM) decreased considerably in both algal DOM sources after UV exposure (16.8% and 20.0% of DOM, respectively), whereas those of hydrophilic acids (HiA; carboxylic acids-like DOM) increased as much as the decrease of the HiB fraction. Capillary ion electrophoresis (CE) analysis showed that several carboxylic acids increased significantly after UV exposure, further confirming an increase in HiA fractions. The results of this study clearly indicate that algal DOM can be changed in its chemical composition as well as biodegradability without complete degradation by UV radiation.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.286-294
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• 2003

This study was attempted to understand seasonal dynamics of phyto- and zooplankton communities in shallow, eutrophic Lake llgam and to compare them with the PEG (Plankton Ecology Group) model. Seasonal succession pattern of phytoplankton community was similar to PEG model as Chlorophyceae and Baciliphyceae increase during spring and autumn fellowed by increase of Cyanophyceae. However, based on the cell density and biomass, a dominant phytoplankton community differed with PEG model: Cyanophyceae had been a dominant community throughout a year, except for ice-cover period during which Chlorophyceae was a dominant group. In spring, when ice melted and dissolved nutrients in water column increased, the increase of Chlorophyceae occurred: when nutrients (DIN and DIP) rapidly decreased, Cyanophyceae increase occurred. Microcystis, Oscillatoria, Lyngbya, Merismopedia were maior dominant species of Cyanophyceae and their cell density and/or biomass was the highest in October 2000 (12.9${\pm}$5.8${\times}10^5$ cells/ml, 3.5${\pm}$0.9${\times}10^3{\mu}gC/l$). Cyanophyceae biomass showed positive relationship with chlorophyll a ($r^2$ = 0.71,P< 0.001) and TP concentration ($r^2$ = 0.62, P< 0.001). Small-sized rotifers such as Keratella cochlearis, increased between March and May when Chlorophyceae increased. Both high standing crop of copepods and cladocerans, such as Diaphanosoma brachyrum and Bosmina longirostris occurred between June and September accompanied with the increase of Dinophyceae and Bacillariophyceae. There was no evidence that clear-water phase was caused by zooplankton grazing. The diversity and evenness index of phyto- and/or zooplankton increased with chlorophyll a concentration. These results suggest zooplankton grazing and limiting nutrient deficiency could lead to change of phytoplankton biomass, but not the phytoplankton community in Lake llgam.

• Applied Microscopy
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• v.38 no.3
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• pp.175-183
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• 2008

Liver regeneration is a result of highly coordinated proliferation of hepatocytes and non-parenchymal liver cells. At this process, induction of metallothionein (MT), which is low molecular and cysteine rich, has been reported. The present study was carried to find the ultrastructure of hepatocytes and determine the expression of MT in regenerating rat liver after partial hepatectomy. As a result, the remnant liver after PH grew fast from 1 day until 7 days. Various changes were morphologically observed. Disintegration of cell plates and liver lobule appeared shortly after PH. And hepatocytes showed the rapid proliferation, characterized by high nuclear cytoplasmic ratio, weak intercellular junctional complexes, chromatin condensation, increase of ribosomes and mitochondria, and temporary increase of lipid droplets. Finally, remodeling of the liver lobule was completed through the rearrangement of blood vessels and cell plates by 7 days after PH. On histochemistry, immunoreactivity indicating the presence of MT appeared moderately throughout the cytoplasm of control rat hepatocyte. After PH, positive reactions for MT increased at the cytoplasm and the nucleus. These results suggest that the remnant liver cells immediately entered cell proliferation and increase of MT expression after PH. It is thought that MT protein might be associated with transfer of some factors needed to cell division from the cytoplasm to the nucleus for regeneration of the liver after PH.