• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.835-842
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• 2022

Several countries are establishing management systems for aquaculture environment, and fishery environment assessment is one of them. The fishery management law amended in 2013 stipulates that a fishery environment assessment should be performed when a fish cage farm's license is extended. The purpose of the fishery environment assessment is to promote sustainable fishery, increase the fishery production capacity, and increase the fishermen incoming by implementing evaluation and improvement measures through scientific methods. The analysis items of fishery environment assessment include the Benthic Health Index (BHI), which is a biological index based on the macrobenthic polychaetes community, and total organic carbon (TOC), and the two items are scored and used for evaluation as a single grade. This study explains the selection process of BHI and TOC, which are evaluation items for fishing ground, and ecological significance of the calculated evaluation grades.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.161-168
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• 2008

The ecological environmental zones in coastal area, like tidal flat and salt marsh, were gradually decreased due to large scale of coastal development projects, reclamation and so on. Therefore, the development of artificial tidal flat and salt marsh has been emphasized in coastal area as mitigation concept and studies on related this background has performed. But studies on the quantitative evaluation for degree of restoration were insufficient. In this paper, as a fundamental study for evaluation of restoration on the creation of ecological environmental zones in coastal area, it was conducted that the monitoring and experiment for bio-chemical factors (bio-diversity, population and biomass of macro-benthos, survival ratio of reed, the number of heterotrophic bacteria and physico-chemical characteristics such as COD, IL, TN, TP and pH) using a in-situ pilot plant of tidal flat (Zone. P1) and salt marsh (Zone. P2), which was distinguished by content of dredged soil, in Jinudo, Nakdong estuary. From results of this study, the restoration index (RI), for evaluation concerning degree of restoration on the creation of ecological environmental zones in coastal area, was suggested and quantitative evaluation was performed using a restoration index (RI).

• Journal of Marine Life Science
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• v.8 no.2
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• pp.121-127
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• 2023

The study was performed in order to understand the association between organic matter content in the sediments and the distribution of macrobenthos in the intertidal zone of the Muan bay. The sediment samples obtained from 21 sampling sites in August 2019 were analyzed for sediment composition and organic matter content (Ignition loss; IL and Total organic carbon; TOC). Further the macro benthos was sorted and enumerated. The sediments of inner area of bay has coarser composition where mouth part of bay, the sediments were predominantly silty. The highest organic matter content (both of IL and TOC) was measured at station 10 located near the Mokpo area while the lowest values was measured at station 20 adjacent to the north side of the bay. The 4 most abundant species accounted for more than 10% of all specimens were Assiminea sp., Musculista senhousia, Cerithideopsilla cingulate and Heteromastus filiformis. The maximum number of species and density were observed at station 10. Cluster analysis and non-metric multidimensional scaling (MDS) allow identification of four benthic assemblages based on species abundance. The correlation analysis revealed that there was a significant difference (p<0.05) in the density with TOC. Based on the analysis; it was found that the distribution of macrobenthos varied with the differences in sediment composition and organic matter content.

• Korean Journal of Environment and Ecology
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• v.16 no.1
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• pp.34-45
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• 2002

Of the four tidal flat areas(Yeocha-ri, Dongmak-ri, Sundu-ri and Donggum-ri) on Southern Ganghwa Island, the distribution of migratory waterbirds showed a difference in the numbers of individuals and species. Higher numbers of individuals and species were observed on the Yeocha-ri tidal flat. The dominant waterbirds species at the four areas was the Dentin(Calidris alpina). This species showed an occupancy rate(42.0-79.1%) on the Yeocha-ri tidal flat, which was much higher relative to the other areas. The Yeocha-ri tidal flats were higher relative to MSL than the other tidal flats. When the Dongmak-ri tidal flat was covered by sea water, the Yeocha-ri tidal flat was 0.0317$\textrm{km}^2$ in area and on this space we observed many resting waterbirds. The biomass of the waterbirds' potential prey on the Yeocha-ri tidal flat was higher(1.6~2.5$\times$) than other tidal flats. Twenty-three species and 266 individuals were found on the Yeocha-ri tidal flat, which was higher than the tidal flats. The food of Dunlin, which was the dominant species in these four areas, was mainly Reticunassa festiva and Umbonium thomasi(Gastropoda) and Perinereis aibuitensis(Polychaeta). A Dunlin(38.11g) used to eat 1,295 individuals of these food items for daily basal energy. Gastropod, its density was highest on Yeocha-ri tidal flats. The distribution of waterbirds seemed to be closely related with the distribution of the benthos, space and safety of resting site. We suggest that the environments of tidal flats, which are rich foraging habitats, are important factors for conservation of waterbirds.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.97-105
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• 2011

This study investigated the community structure and spatio-temporal variation of macrobenthic assemblages around Gijang Province, East Sea of Korea. Macrobenthos collected seasonally using a modified van Veen grab sampler from March to November 2006. A total of 157 macrobenthic fauna were collected. The overall average macrobenthos density were $552 \;ind/m^2$. The species number of macrobenthos was in the range from 62 in winter and spring to 122 in autumn. On the other hand, abundance fluctuated between 6,540 (in spring) and 17,920 (in autumn) inds./$18m^2$. Cluster analysis and non-metric multi-dimensional scaling (nMDS) were applied to assess the spatio-temporal fluctuation in the macrobenthic assemblages. Cluster analysis and nMDS ordination analysis based on the Bray-Curtis similarity identified 3 station groups. The group 1 (station 8~10, 12, 13, 17 and 18) was characterized by high abundance of the polychaete Lumbrineris longifolia, the bivalve Ennucula tenuis and the Amphipoda spp., with mean phi range from $6.2{\Phi}$ to $7.1{\Phi}$ (above 50m water depth). The group 2 (station 5~7, 11, 14~16) was numerically dominated by the po1ychaete Ampharete arctica and the bivalve Theorafragilis (mean phi: $6.0{\sim}7.0{\Phi}$; within 40 m water depth). Finally group 3 (station 1~4) was characterized by high density of the polychaetes Magelona japonica and Sternaspis scutata, with mean phi range from $3.5{\Phi}$ to $6.9{\Phi}$ (below 30 m water depth). In conclusion, the Macrobenthic community structure showed a distinct spatial and temporal trend, which seemed to be related to the water depth and sediment composition.

• Korean Journal of Environmental Biology
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• v.24 no.4
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• pp.392-407
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• 2006

This study was seasonally undertaken to investigate the benthic polychaetous community along the South-eastern coast of Geoje Is., in February 2004 to November. The macrobenthic fauna showed mean density of 953 md. $m^{-2}$ in February, 1,193 ind. $m^{-2}$ in May, 1,130 ind. $m^{-2}$ in September and 991 ind. $m^{-2}$ in November. Major faunal groups are polychaetes, crustaceans and mollusks, corresponding to 81.6%, 7.9%, 7.0% in total mean density during the sampling seasons, respectively. There was significant difference (two-way ANOVA, p<0.001) among stations in densities of polychaetes. But no significant relationship could be found between the densities of polychaetes and sampling seasons (two-way ANOVA, p>0.05). The density and the species number of polychaetes were high in the coastal area near the Jisepo port, independent of sampling seasons. Several indicator species for the organically enriched environments such as Lumbrineris longifolia, Tharyx sp., Heteromastus filiformis showed high densities during all study periods. Also Magelona japonica included in Ecolgical group I was the most abundant in the whole study period except for February. Cluster analysis on the basis of the species composition showed that the study area could be divided into 3 regions. The density of benthic polychaetes in the coastal area near Jisepo was higher than that in the other assemblages of the study area, due to some predominant opportunistic species, such as Lumbrineris longifolia, Tharyx sp. and Heteromastus filiformis. In addition, the two-way ANOVA showed significant differences among the distribution of AMBI (AZTI's Marine Biotic Index) values, both in sampling stations (p<0.001) and seasons (p<0.01). According to the classification proposed by Borja et at. (2000), the study area was slightly disturbed site.

• Ocean and Polar Research
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• v.25 no.2
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• pp.183-200
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• 2003

In order to assess the ecological changes induced by organic pollutants of the Shihwa Lake, BPI (Benthic Pollution Index) based on the benthic faunal community was employed. It was modified from Infaunal Trophic Index (ITI), and recommended as a pollution detecting method for the environmental assessment. The BPI values were calculated from the benthos data, which were collected for three terms: in 1980, before the Shihwa Lake was built up; in 1994-1997, which the Shihwa Lake was completely isolated from the outer seawater; in 1997-1999, after inflow of the outer seawater. Since the Shihwa Dike was constructed in February 1994, the pollution intensity of the lake had been increased from the narrow and inner part of the former Gyeonggi Bay and spread fast along the coast line of the Shihwa Lake. Then, in 1996 it showed the very high BPI levels all around the Lake. This serious polluted condition had been lasted till 1997, when the inflow of the seawater was begun. In 1998, from the nearest part of the Shihwa Gate, the BPI levels gradually became low in most area of the Lake, except its inner and narrow part. These greatly lowered BPI levels mean that the seawater inflow could be assumed to affect positively in the lake. Furthermore, BPI gave the same results from the other environmental assessment based on the abundance and the species richness of macrobenthic community. It shows that BPI could be useful as an effective method to assess the marine environment and evaluate the status of environmental conditions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.330-342
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• 1998

Benthic environmental parameters were analysed at 40 stations during the period from April 1995 to February 1996. such as water temperature, salinity, and dissolved oxygen (DO)-concentration in the surface and bottom water layers, grain size, chemical oxygen demand (COD), ignition loss, particulate organic carbon (POC) in the sediment of Youngsan River estuary. The water temperature ranged from 4.1 to $29.8^{\circ}C$ in the surface and 4.0 to $20.7^{\circ}C$ in the bottom layers. Salinity ranged from 15.1 to $33.6\%_{\circ}$ in the surface and 31.5 to $33.2\%_{\circ}$ in the bottom layer. The salinity in the outer pan of the study area was higher than that of inner area from autumn to spring, whereas they remained lower in summer. Dissolved oxygen concentration ranged from 5,1 to 11.2 $mg/\ell$ in the surface, and 0.79 to 10,2 $mg/{\ell}$ in the bottom layers. Hypoxic condition ($\le2.0mg/\ell$) was developed in the bottom water layer from Youngsan dike to Mokpo Harhour in summer due to the summer stratification. The surface sediment type was silty clay with a mean grain size of $9.12{\pm}0.45\phi$. The range of COD was from 6.15 to $15.49mgO_2/g$ with a mean of $10.59{\pm}12.64mgO_2/g$. The COD in the inner stations was relatively higher than that of outer stations, and decreased toward the outer part of the study area. Ignition loss (IL) ranged from 3.35 to $15.45\%$ with a mean of $5.96{\pm}1.91\%$. Principal component analysis was carried out from the following five environmental parameters: water temperature, dissolved oxygen in the bottom layer and mean grain size, clay content and COD in the sediment. The forty stations in the study area were classified into three stational groups. Group I was located in the inner part of the estuary characterised by relatively low surface salinity and bottom water temperature, fine sedimemt texture, high organic matter and low dissolved oxygen concentration during the summer. Meanwhile, Group III showing relatively high bottom salinity and water temperature was located in the outer part of the estuary characterising coarse sediment and low organic content in sediment. Group II was between Group I and Group III. The division of the areal groups had high correlations to the DO in the bottom layer and clay content in the sediment.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.286-294
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• 2014

The purpose of this study is to investigate the effects of applying density current generator (hereafter referred to as DCG to large lakes on the operating conditions of DCG, de-stratification, water quality improvement and inhibition of algae occurrence. As a result of a survey conducted to derive the optimum operating parameters of DCG in a condition to minimize eco-toxicity, the following conclusions were obtained. During the survey period, a marked stratification appeared in September to October 2011 and May 2012. At this time, the average depth of water to form thermocline was found to be $5{\pm}2$ m, so the location of discharge port for the operation of DCG was determined to be about 5 m below from the surface. To minimize the adverse effects of benthos and obtain the effect of water mixture at the time of water circulation, the mixing ratio of surface water and deep water was designed to be 3:1 by means of ecotoxicological assessment on the DCG operating characteristics. To select the appropriate operating hours for DCG, DCG was operated by 12 hr, 24 hr, 36 hr and 48 hr. As its result, the formation of thermocline did not occur during the operation of 36 hr. Also, It was effected that start reoperating from 3rd day after stop 2days under the condition of operated during 36 hr with calculated power consumption. Under the above conditions, the results of DO and water temperature analysis during the operation of DCG showed that the stratification, which was distinct previously, appeared to be weak, and relatively lower levels than those before operation were found as a result of water quality analysis on COD and chlorophyll-a, which leads to the conclusion that the water body is maintained at a stable condition due to the circulation of water by the occurrence of density current resulting from the operation of DCG.

• Korean Journal of Environment and Ecology
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• v.23 no.4
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• pp.353-364
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• 2009

This study was conducted to evaluate the effect of erosion control works on the stream ecosystem in a mountain torrential stream. The species composition of benthic macroinvertebrates and biological water quality were investigated before and after construction of erosion control works at 5 sites. The total number of benthic macroinvertebrates before construction was 3,086 individuals including 4 phyla, 6 classes, 11 orders, 22 families, and 25 species, but after construction it has decreased to 1,208 individuals including 4 phyla, 6 classes, 10 orders, 17 families, and 19 species. Especially, the diversity, richness, and evenness indices, which were calculated based on existing number of biological species, have decreased or not produced at the erosion control sites, where biological species were not found or the minimum number of species were found. The results of community analysis of benthic macroinvertebrates and ESB(Ecological Score of Benthic macroinvertebrate community) indicated that the environmental qualities of the stream based on saprobity, environmental condition, and water quality decreased after the construction at all sites: before construction, the top of the stream was satisfactory and some satisfactory, the middle was some defectiveness, and the lower was defectiveness and very defectiveness; after construction, all parts of the stream except some parts of the top were very defectiveness. Moreover, the water quality of torrential stream was rated between I to III before construction, but after construction, it declined to $IV{\sim}V$ except control. The habitat damage of benthic macro invertebrates occurred at all investigation sites after the construction of erosion control works led to reduction of the number of biological species and water quality deterioration. The results reported in this study were collected directly after the construction of erosion control works. Therefore, additional studies are needed to further explore the effect of disaster-prevention of erosion control works and the recovery process of stream ecosystem through long term monitoring.