• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.214-222
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• 2006

Dominant species of macrobenthos were analyzed based on differentiation of three distinct methods: the density based method, the biomass based method and LeBris method, by considering the frequency of occurrence using quantitative data collected over 5 years (1993-1998) at 21 stations in Chonsu Bay. Sedimentary environments as well as species composition and diversity showed the spatial and temporal distribution patterns. The ranks of dominant species as determined by the density based method were more similar to the results by the LeBris method than to those from the biomass based method. Considering the temporal variation, LeBris method were more efficient than any other methods for the determination of dominant species in Chonsu Bay. Lumbrineris longifolia, Theora fragilis, and Moerella jedoensis were recognized by all three methods. A one-way analysis of variance indicated spatial distributions patterns among most of the dominant species. These species showed positive correlations to sedimentary parameters such as mean grain size. However, T. fragilis and Paraprinospio pinnata showed the temporal patterns in their distribution, and were also correlated to the benthic environment, organic content and dissolved oxygen. Some dominant species, e.g., T. fragilis, S. scutata, G. gurjanovae proved to be useful benthic indicators based on the environmental variations determinated by long-term benthic ecological monitoring in Chonsu Bay.

• Journal of the korean society of oceanography
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• v.33 no.1-2
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• pp.18-27
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• 1998

Based on 53 quantitative samples collected in April (23 stations) and August (30 stations) of 1993, the species composition, distribution and abundance of macrobenthic invertebrates and bottom characteristics in Chonsu Bay were conducted. Bottom sediments consisted of mud at the close to the dyke, sandymud in the central bay, and coarse sand in the mouth of the bay. A total of 273 species (177 species in April and 200 species in August) were identified. Mean density per sampling station was 480 ind./m$^2$ in April and 1126 ind./m$^2$ in August, respectively. Number of species and densities decreased in the northern part of the bay. The macrobenthos showed a temporal difference in species composition, range of distribution, and community delimitation caused by larval settling. Although during the settling period in summer, large numbers of juveniles added in most of regions, unrelated to environmental conditions, but, successful recruitment may has been a rare event locally Theora fragilis (bivalve), Lumbrineris longifolia(polychaete), Neptys oligobranchia (polychaete) were numerically dominant, but their densities varied seasonally. Community structures of macrobenthos in Chonsu Bay were affected by several bottom environmental conditions, related to tidal current speed, regionally.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.262-271
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• 2000

This study was carried out to clarify the spatial and temporal patterns of benthic environments and macrobenthos on the subtidal soft-bottom in Chonsu Bay. Seasonal surface water temperature was similar to the bottom layer, but freshwater discharges into the outlets dereased the surface salinity around the dyke in summer. Bottom dissolved oxygen was decreased deeply around the dyke and created the de-oxygenated layer during summer. Sediment grain size was consisted of finer at the neighboring of the dyke than the mouth of the bay. Organic matters including the sediment were decreased at the mouth of the bay. A total of 311 species ($769\;ind./m^2$) were identified. Polychaetes were the most abundant faunal group in the number of species and densities. The number of species revealed the spatial patterns that it was higher in the mouth of the bay, and their densities showed seasonal changes by mass recruitment occurred at the most of the area in summer, At this time, opportunistic species, Lumbrineris iongifolia and Theora fragilis, were also recruited massively. Chonsu Bay were classified into five station groups by the cluster analysis. The dominant species around the dyke were composed to opportunistic species, those in middle area were Sternaspis scutata, Paraplionospio pinnata, and those in the mouth of the bay were Mediomastus californiensis, Nephtys polybranchia. Seasonal fluctuations and spatial difference of environments seem to have influenced to the species compositions and affected to the stability of benthic ecosystems spatial-temporally In Chonsu nay.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.4
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• pp.151-164
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• 1998

Changes in tides and tidal currents in Chonsu Bay caused by the construction of Seosan A and B reclamation regions have been investigated using a depth-integrated two-dimensional tidal model. Three water level recorders were deployed for about one month and used for the specification of the open boundary condition. The computed currents were found to be in a good agreement with the measurements at two stations within Chonsu Bay. Comparison of the absolute velocities computed with the conditions before and after the embankment clearly shows that the reduction in tidal current amplitude is evident throughout the bay and the magnitude of the reduction increases to the north. Calculation shows that the embankment has advanced the time of drying at the northern part of the bay by about 51 minutes and has increased the exposure time by about 23 minutes. The high water time has advanced by about 1 hour, lowering the high water level by about 15 cm.

• Journal of the Korean Geographical Society
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• v.15
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• pp.1-15
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• 1977

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.1
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• pp.71-83
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• 1996

Seasonal samples of demersal fish in Chonsu Bay were collected by an otter trawl from May 1991 to February 1992, and analyzed in terms of species composition, abundance and community structure. These data were compared with those obtained just after reclamation in 1986. The species composition of the demersal fish of the present study shows a similar seasonal trend to the previous one. However, the abundance in some species was changed. Gobiid fish such as Cryptocentrus filifer, Chaeturichthys stigmatias and Acanthogobius hasta were diminished, while Repomucenus lunatus, Leiognathus nuchalis and Sillago japonica were increased. This change in abundance of the fish seems to be related to sedimentation of fine particles and irregular discharge of freshwater with high organic content from the reservoir to the bay.

• Journal of the Korean Geographical Society
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• v.22
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• pp.1-9
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• 1980

이 글에서는 다음의 내용을 다루었다. 1. 연구의 목적과 방법 2. 연구지역의 개황 3. Strahler방식에 의한 갯골차수의 체계 4. Hydraulic geometry

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.654-664
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• 1998

Seasonal variation in species composition and abundance of pelagic fish in Chonsu Bay were determined by analyzing monthly samples collected using a set net from March, 1992 to January, 1993. The data in this study were compared with those of 1981$\~$82. Of 63 species identified, Engraulis japonicus, Ammodytes penonatus, Enedrias fangi and Sardinella zunasi predominated in abundance. Especially E.japonicus occupied $87\%$ of total number of individuals. In spling, fish abundance increased by recruitment of lariat E. fanti as well as adults of E. japonicus, A. personatus and S. zunasi. These adults moved towards the open sea after spawning in early summer. A large number of juveniles was then collected from August until December. The seasonal change in species composition from the present study showed a similar trend to that occurred in 1981$\~$82. However, larger number of pelagic fish was caught in 1992$\~$93 than in 1981$\~$82. This result seems to be related to the higher water temperature (>$2^{\circ}C$) than the average mean temperature in spring and autumn, implying that higher temperature provides favorable conditions for spawning and growth of the fish.

• 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.

• Korean Journal of Environment and Ecology
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• v.29 no.3
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• pp.421-430
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• 2015

This study was carried out to understand the ecological variations of macrobenthos communities by construction dikes in the subtidal zone of Chonsu Bay. This study analyzed the distribution of benthos, the dominant species, spatial and temporal changes of benthos communities and benthic pollutions in the subtidal zone of Chonsu Bay. A total of 252 species of subtidal macrobenthos with a density of $681ind./m^2$ were studied. In all the seasons, the species diversity was found to be higher near the mouth of the bay. For all the seasons of the year, Lumbrineris japonica was found to be the most dominant species. These dominant species were found to have positive correlations with species diversity and sedimentary parameters such as organic content in sediments. Dominant species of benthos as well as species composition and diversity showed spatial and temporal distribution patterns.Benthic Pollution Index (BPI) values estimated for the stations near the embankment were in the 4~5 levels, which indicates that the organic matter has been polluted. And as for the stations near the mouth of the bay, the BPI values were in the 1~3 levels, which indicates that the organic matter has been relatively less polluted. According to the SAB-curve analysis, the number of transitional point stations became less in the mouth of the bay.