• 한국해양학회지
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• v.21 no.3
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• pp.156-170
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• 1986

The phytoplankton ecology of estuarine waters was investigated in the Kyeonggi Bay from May 1981 to September 1982 on monthly basis. In this study area, a total of 228 phytoplankton species was identified. Among these taxa, the most dominant species are diatoms in this area. Tychopelagic plankton occupies 40.4% of total species. The percentage of tychopelagic plankton density ranged from 10.2% in September to 92.7% in March of monthly standing crops. From late autumn to early spring, the percentage values are more than 72%. They play an important role from late autumn to early spring in this estuarine plandton community. These tychopelagic planktons are induced from benthic diatoms. Because the bottom shear stresses generated by the tides and winds are stronger than the adhesive and tractive force of benthic diatoms, most of benthic diatoms must be resuspended into tychopelagic suspensions during autumn and winter. Paralia sulcata is the most important tychopelagic plankton as an indicator species of water mixing in the eastern coastal area of Yellow Sea. This species seems to have even broader tolerance to the environmental stress than Skeletonema costalum, and tends to fill the gaps in winter, when the phytoplandton is relatively unsuccessful. Skeletonema costatum and Chaetoceros debilis are dominant in other seasons. Typical blooms of phytoplankton occur in spring and early autumn, The first bloom is started by Skeletonema costatum in early May, second peak is formed by various diatom population in September.

• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.730-736
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• 2007

The heterogeneity of forest environment plays an important role in the structure and dynamics of tree population, the composition of forest community, and the maintenance of species diversity. Based upon the research data of the nine hectare permanent plot in the typical mixed broadleaved-Korean pine forest, this study was conducted to analyze the characteristics of spatial pattern of Acer tegmentosum population for seedlings, saplings, and living and dead trees so as to evaluate the effect of micro-topography on spatial pattern of the species. The results noted that A. tegmentosum preferred to gentle slopes. There was no difference in density of seedlings by the variation of aspect, but the density of saplings, and living and dead trees was high on the western and southeastern slopes. Living trees of A. tegmentosum showed the clumped pattern for all scales within 150 m and highest at the scale of 30 m. Dead stems of the species indicated the clumped pattern within 111 m, highest at the scale of 72 m, and random pattern beyond the scale of 111 m (P < 0.01 ). The similarity of occurrence by developmental stages of A. tegmentosum showed that seedlings vs. saplings, saplings vs. living trees, and living trees vs. dead stems had highly positive correlation to each other, respectively (P < 0.01 ), indicating that the occurrence of previous developmental stages was positively correlated to following stages.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.11
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• pp.1660-1666
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• 2017

Objective: Burial is associated with environmental effects such as the contamination of ground or surface water with biological materials generated during the decomposition process. Therefore, bacterial communities in leachates originating from the decomposing bovine carcasses were investigated. Methods: To understand the process of bovine (Hanwoo) carcass decomposition, we simulated burial using a lab-scale reactor with a volume of $5.15m^3$. Leachate samples from 3 carcasses were collected using a peristaltic pump once a month for a period of 5 months, and bacterial communities in samples were identified by pyrosequencing of the 16S rRNA gene. Results: We obtained a total of 110,442 reads from the triplicate samples of various sampling time points (total of 15 samples), and found that the phylum Firmicutes was dominant at most sampling times. Differences in the bacterial communities at the various time points were observed among the triplicate samples. The bacterial communities sampled at 4 months showed the most different compositions. The genera Pseudomonas and Psychrobacter in the phylum Proteobacteria were dominant in all of the samples obtained after 3 months. Bacillaceae, Clostridium, and Clostridiales were found to be predominant after 4 months in the leachate from one carcass, whereas Planococcaceae was found to be a dominant in samples obtained at the first and second months from the other two carcasses. The results showed that potentially pathogenic microbes such as Clostridium derived from bovine leachate could dominate the soil environment of a burial site. Conclusion: Our results indicated that the composition of bacterial communities in leachates of a decomposing bovine shifted continuously during the experimental period, with significant changes detected after 4 months of burial.

• KSBB Journal
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• v.20 no.6
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• pp.431-437
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• 2005

Molecular methods were employed to investigate microorganisms in a thermophilic continuous stirred tank reactor(CSTR) used for continuous $H_2$ production. The reactor was inoculated with heat-treated anaerobic sludge and fed with a glucose-based medium. Denaturing gradient gel electrophoresis showed dynamic changes of bacterial populations in the reactor during 43 days of operation. Gas composition was constant from approximately 14 days but population shift still occurred. Populations affiliated with Fervidobactrium gondwanens and Thermoanaerobacterium thermosaccharolyticum were dominant on 21 and 41 days, respectively. Keeping pH of the medium at 5.0 could suppress methanogenic activity that was detected during initial operation period. $CH_4$ and mcrA detected in the samples obtained from the reactor or inoculum suggested the heat treatment condition employed in this study is not enough to remove methanogens in the inoculum. PCR using primer sets specific to 4 main orders of methanogens suggested that major $H_2$-consuming methanogens in the CSTR belong to the order Methanobacteriales.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.143-151
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• 2016

Shoreline armoring is a globally used engineering strategy to prevent shoreline erosion along stream, lake and reservoir coastlines. Armoring alters the land-water interface and has the potential to affect shoreline vegetation by changing nearshore geomorphology, hydrology, sediment composition and water quality. We quantified the effects of the artificial disturbances and alternation of the land-water interface on the community structure and distribution of shoreline vegetation in a large reservoir, Uiam Reservoir, Korea. More than 60% of shorelines were disturbed by armoring with retaining wall of concrete block, riprap and gabion in the Uiam Reservoir. The results of detrended correspondence analysis showed that the vegetation structures of the shoreline modified by armoring changed from hydrophyte-dominated to hygrophyte-dominated ecosystems. The shoreline armoring caused the disruption of gradual continuity in the water-land interface and the biological invasion by alien plants. The changes in distribution area of shoreline vegetation showed that the area of hydrophytic vegetation decreased and that of hygrophytic vegetation increased from 2010 to 2013. In conclusion, the human disturbance such as armoring, road construction, recreation etc. could lead to terrestrialization, the loss of transverse continuity and biological invasion in the shoreline vegetation of the Reservoir Uiam. Our findings suggest that redesigning or removing shoreline armoring structures may benefit nearshore hydrophytic vegetation for the conservation of novel shoreline ecosystems.

• 한국해양학회지
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• v.25 no.4
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• pp.217-228
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• 1990

In order to study on the relative significance of nanoplankton in Chonsu Bay, nanoplankton samples were collected and analyzed monthly from September, 1985 to August, 1986. A total of 33 taxa representing 6 phyla, 8 classes, 13 orders, 17 families, 25 genera, 33 species have been identified. Micromonas pusilla, Pedinomonas mikron, Pyramimonas grosii, Chroomonas lateralis, Pyrenomonas salina (=Chromonas salina), chroomonas sp., Cyclotella sp., Gonyaulax sp., unidentified sphericl monads (2-5um and 6-8um in size), and unidentified naviculiod form were common species. the distribution of nanoplankton standing crops showed a great temporal and spartial variations. Nanoplankton standing crops was highest in October, 1985 and lowest in September, 1985. The abundance of nanoplankton in Chonsu Bay may be within the range of that of most coastal areas. Unidentified spherical monada (2-5um and 6-8um in size) were most dominant. Chlorophyll-a concentrations of nanoplankton ranged from 0.81 to 4.78ug/l and daily primary productivity by nanoplankton, 16.4 to 767.2 mgC/m$^2$/day. Nanofraction of total phytoplankton cell number accounted for 38% to 93% (average 6%), chlorophyll-a and primary productivity of nanoplankton 25 to 87% (average 64%) and 9 to 87% (average 53%), respectively. The results implied that nanoplankton could be a considerable contribution to phytoplankton biomass and primary productivity in Chonsu Bay phytoplankton community.

• 한국해양학회지
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• v.19 no.1
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• pp.44-55
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• 1984

Abundances of small fishes that utilized seagrass meadows of Redfish Bay, Texas, were analyzed quantitatively to determine monthly changes of this concentrated subtropical fish community during 1982-1983. an effective quantitative sampler, a 1-㎡ thrown cage, yielded a total of 10,223 fishes that comprised 40 species in 23 families, with average total densities about 15 fishes/㎡ in shoalgrass meadow and 6 fishes/㎡ in turtlegrass meadow. The darter goby, pinfish, code goby, and Gulf pipefish were the four most abundant species, and accounted for approximately 85% of the number of fish collected. However, the two different meadows had different relative abundances of fishes. The darter goby numerically dominated shallower shoalgrass meadow, while the pinfish and code goby were the commonest fishes in deeper turtlegrass meadow. Seasonal changes in both species composition and abundances of fish populations were major characteristics in these subtropical seagrass medows. Peak abundance of total fishes occurred during spring, with a secondary peak in fall. Lowest abundance of total fishes occurred in winter. Each abundant species showed its own seasonal abundance pattern, and had a peak abundance 1-3 months separated from other species, with some overlap of increased larval recruitment. Such distinct seasonal abundance patterns with different times of peak recruitment. Such distinct seasonal abundance patterns with different times of peak recruitment among fish species seem to permit use of the seagrass habitats with reduced, seasonal competition.

• Journal of Wetlands Research
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• v.16 no.4
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• pp.353-362
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• 2014

The purpose of this study is to investigate the effect of micro-topography to vegetation pattern in Dunchon-dong wetland. To characterize the effect of micro-topography, changes in water level and vegetation pattern were monitored from 2007 to 2008. Depending on the relative elevation, the study site was divided into 4 sectors. The relative areas of sectors in ascending order were 11%, 10%, 18% and 24%, respectively. During investigation period, average water pH was 6.10 (${\pm}0.13$), electron conductivity was $51.5({\pm}6.0){\mu}s/cm$, $PO_4$-P, $NO_3$-N and $NH_4$-N concentration were $0.04({\pm}0.02)mg/L$, $0.14({\pm}0.07)mg/L$, and lower than 0.01mg/L, respectively. Water level was very changeable in low-water season because the area of lowest sector was small. This characteristic increased the effect of difference of accumulated precipitation from March to April in 2007 and 2008 to plant community composition in lower sectors. Different plant guilds dominated respective sectors and annual plants were major dominant species in the study site. This study suggested that the elevation gradients are necessary to create the habitats for various plant guilds in wetland.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.181-189
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• 2018

This study was performed to analyze the dynamics and distributional condition of biological community and to support the basic information about the estuarine ecosystem management by using the intensively surveyed results by each taxon experts around Tamjin river. We analyzed the biological diversity, abundance, correlation among species, and ecological characteristics about 11 taxa groups including vegetation, fish, birds, mammals, etc. in the Tamjin river estuarine ecosystem. We classified vegetation types into 7 physiognomic types and 18 communities according to habitat conditions with the physical environments and salinity. In total, 1125 species including 9 species of endangered species were identified in research area. The species composition and distributional characteristics of each taxon were corresponded to the environmental characteristics of the estuarine ecosystem. Especially, the species diversity and distribution were clearly distinguished in the river according to the difference of the environmental factors such as flow rate, salinity, and soil. Despite the disturbance factors such as barrage and levees, the biodiversity and its distribution were evaluated to be high level under the current environmental conditions. However, loss or reduction of wildlife habitat due to reclamation, embankment, barrage installation and expansion of farmland has been identified as a major threat to the diversity and health of the local ecosystem. The results of this study can be used as a basic data to cope with various development pressure and damage crisis of the whole estuaries including Tamjin river.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.265-272
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• 2001

The diversity of acid-tolerant epiphytic bacterial communities on deciduous oak tree (Quercus dentate Thunb.) leaves was examined both in the natural forest area with a clean air and in the industrial estate to assess effects of acidic depositions to the phyllosphere using 16S rDNA sequence data. A total of 444 acid-tolerant epiphytic bacterial clones were obtained, resulting in 17 phylotypes by performing a analysis of restriction fragment length polymorphism (RFLP) for PCR-amplified 16S rDNA products. A very low diversity of dominating acid tolerant bacterial communities in both areas was found, just 2 subphyla groups, $\gamma$-Proteobacteria and low-G+C gram-positive bacteria. As tree leaves grow older, diversities of acid-tolerant bacteria on them significantly increased. The community structure of acid-tolerant epiphytic bacteria consisted of Pseudomonas and Enterobacteriaceae groups in the $\gamma$-Proteobacteria subphylum, and Streptococcaceae and Staphylococcus groups in the low-G+C gram-positive bacteria subphylum. The direct influence of acidic depositions on bacterial phylogenetic composition could not be detected especially when higher taxonomic levels such as subphylum, but at narrower or finer levels it could be observed by a detection of Xanthomonadales group belonged to the $\gamma$-Proteobacteria only in the industrial area and of Acetobacteraceae group belonged to the $\alpha$-Proteobacteria. There remains that these specific acid-tolerant epiphytic bacterial groups could be used as indicators for assessing effects of acidic depositions on the phyllosphere.