• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.287-304
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• 2007

This study was carried out to investigate spatio-temporal variations of benthic environment and macrobenthic polychaete communities in Gamak Bay where excessive organic matters from untreated sewage effluents and fish and shellfish farming activities have been accumulated in certain regions. Such environmental variables as sediment composition, organic content, acid volatile sulfide and dissolved oxygen content etc. were measured and polychaete specimens were taken in September 1999 and February 2000. In September 1999, organic contents were up to three times higher in the northwestern part of the bay and the area closed to Gukdong harbor than in the rest of the bay. In particular, benthic environment of the northwestern part of the bay was extremely deteriorated by the occurrence of hypoxia and highly concentrated sulfide. Of 28 stations investigated in summer, 5 stations located in the northwestern part were azoic. In the rest of the stations, a total of 119 polychaete species were sampled with a mean density of 900 $ind./m^2$. While species richness was higher in the entrance and central part of the bay where water exchanges with open sea were relatively active, density was higher in the moderately enriched stations neighbouring Gukdong harbor and fish farms where such potential indicators of organic pollution as Aphelochaeta monilaris, Lumbrineris longifolia were largely dominant. In February 2000, a total of 81 polychaete species appeared with a mean density of 2,802 $ind./m^2$ from 12 stations sampled in winter. Azoic areas were recolonized by Capitella capitata, Pseudopolydora paucibranchiata and Dipolydora socialis which showed maximum density in the innermost station. On the other hand, the rest of the stations were dominated by Euchone alicaudata and Praxillella affinis. The configuration of the stations sampled in summer and winter on the multidimensional scaling plots reflected the position of each stations within the bay in which there were great differences in organic content, sulfide concentration and oxygen content rather than in sediment composition. Therefore, heterogeneities in polychaete community structure in Gamak Bay were primarily influenced by the degree of the disturbance depending on the position within the bay.

• 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 Wetlands Research
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• v.16 no.4
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• pp.371-378
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• 2014

The subject of this study is the Gongchon-cheon which is one of the largest streams in Incheon and is closely related to lives of citizen. Comparative analysis is made on the changes of the environment and the ecological condition of Gongchon-cheon after the stream naturalization construction which is completed in July 2009. From the results of the survey, 32 species in 2004, 22 species in 2009 and 46 species in 2010 have been recorded. The number of the species decreased from 2004 to 2009 due to the disturbance of the river environment, and it increased in a short time from 2009 to 2010 because of the recovery of the environment. It demonstrates the stream naturalization construction providing enough environments (dikes and rapids) for the benthic macro invertebrates. The result of the present study is similar with the river's biology index, ESB index, and KSI index, and also it is similar with the pattern of the appearance, which illustrates that the species decreased during the naturalization construction, and increased after the stabilization since the finish of the naturalization construction, and it has been confirmed that the naturalization construction provides the better environment for the inhabitation of organisms.

• 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.

• 한국해양학회지
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• v.24 no.4
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• pp.184-193
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• 1989

An investigation on the soft-bottom macrobenthic community in the inner Kyeonggi Bay was conducted in July, October of 1987 and February, May of 1988. The benthic fauna comprised a total of 87 species and showed mean density of 550 indiv./$m^2$. Major faunal groups are polychaetes, molluks, and crustaceans, corresponding to 64.7%, 17.4%, and 15.2% in total abundance respectively. The most abundant species was Tharyx sp. (10.9%), and followed by Mactra veneriformis (10.5%), Mediomastus sp. (8.6%), and Glycinde sp. (8.0%) etc.. The important species in the intertidal zone were Mactra veneriformis, Hinia festiva, and Nephtys californiensis, whereas those in subtidal channel region were Tharyx sp., mediomastus sp., Sternaspis scutata, and Nephtys polybranchia. The study area could be divided into 4 station groups based on the species composition; two groups within interidal flat and two in channel regions. Each station group sustained its specific benthic faunal assemblage; Mactra-Hinia, Aricidea-Haploscoloplos assemblages in the intertidal flat and Harpiniopsis-Urothoe, Mediomastus-Sternaspis assemblages in the subtidal channel region. The Mediomastus-Sternaspis assemblage showed the highest species number and population density, and also did the highest diversity and evenness indices. The Harpiniopsis-Urothoe assemblage showed the poor species composition and abundance, and so recorded the highest dominance index. Two assemblages in the intertidal flat had the intermediate values in all the biological parameters. The northern channel region of zone S-2 showed the high abundance in species composition, which seems to be caused by the heterogeneous sediment and the organic enrichment from the Han River and the Incheon industrial complex.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.765-776
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• 2019

The purpose of this study is to provide the legal and institutional guidelines and standards that can be used in the whole river restoration project and to analyze and evaluate the performance of the river project. We constructed an assessment system of four biological taxa that can represent the river environments, namely, evaluation indexes and standards of vegetation and birds, benthic invertebrates and fishes. Specifically, the assessment indicator and criteria of biological characteristics are summarized, so that in case of vegetation community, vegetation diversity, vegetation complexity, and vegetation naturalness can be quantitatively assessed through the combination of three indices. Based on the scientific basis of the advanced techniques, benthic invertebrates, fishes, and birds were proposed to quantitatively evaluate assessment grades according to the classification of biological data. In order to evaluate biological characteristics, which are a part of river environmental naturalness, we proposed a comprehensive biological index and evaluation grade applying the weight of these four biological taxa, and it clearly reflects the characteristics of river environment in test bed.

• 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.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.2
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• pp.73-79
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• 1996

This study was conducted to investigate the faunal composition and distribution patterns of macrobenthic community in the deep sea sediments of the KODOS area, the northeastern Pacific Ocean during May 1996. Benthic animals were collected at 25 stations using a spade type box corer. Sediments were sieved through -.3 mm mesh screen. A total of 17 faunal groups in 9 phyla and 363 specimens were identified. Nematoda was the most abundant faunal group which accounted for 30.0% of total abundance. Other dominant faunal groups were foraminiferans (25.1%), harpacticoids (10.2%), xenophyophores (5.2%), and polychaetes (4.7%), Polychaeta was a typically dominant component of macrobenthic community in the study area except traditionally recognized meiofauna taxa. Mean occurrence number of faunal taxa was ca. 6 per 0.01 m$\^$2/, and mean density was estimated as 1,288 indiv./m$\^$2/. The abundance of whole fauna and that of each faunal group was highest at the surface layer of sediment, and decreased monotonously along the sediment depth; 98% of faunal abundance was found within 10 cm depth layer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.524-532
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• 2011

The intertidal benthic macroalgal floras of 19 uninhabited islands were investigated in the Goheung area, South Sea, Korea, in June 2008. Seaweed community structures on the rocky shores of four (Naemaemuldo, Ceoldo, Araedombaeseom, and Jinjioedo) of the 19 islands were also examined. Eighty macroalgal species were identified, including 13 green, 19 brown, and 48 red algae. The maximum number of species was found at Naemaemuldo, with 35 species, and the minimum was at Aredombaeseom, with 21 species. Seaweed biomass ranged from 21.39-76.22 g dry wt/$m^2$, with a maximum at Naemaemuldo, and minimum at Jinjioedo. Sargassum thunbergii was a representative species, distributed widely in the intertidal zone of the four islands. Subdominant seaweeds were Corallina pilulifera and Ulva pertusa at Naemaemuldo and Jinjioedo, respectively. Also, Ishige okamurae was dominant at Ceoldo and Araedombaeseom. Six functional seaweed forms were found at each study site, except for Araedombaeseom, which had four functional groups. On the rocky shores of the four sites, a coarsely-branched form was the most dominant functional group ranging from 44.44-61.90% in species number and 72.42-91. 09% in biomass. In conclusion, among the four study sites, the shore of Naemaemuldo Island had the best ecological status, with the highest number of species, and greatest biomass (mainly brown and red algae) and functional form diversity of seaweeds. Furthermore, on the rocky shore of Naemaemuldo, coarsely branched- and joint calcareous-form seaweeds, which grow in clean and undisturbed environmental conditions, were the representative functional forms.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.1
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• pp.42-47
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• 1997

This study was carried out to investigate the faunal composition and distribution pattern of meiobenthic community in the deep sea sediments of northeastern Pacific Ocean. Faunal samples were collected at 10 stations using a multiple corer and a spade type box corer during May 1996. A total of 18 meiofaunal groups were found, and Sarcomastigophora was the most dominant group which accounted for 35.8% of total meiofaunal abundance. Nematoda (30.8%), Nauplius larvae of Crustacea (11.9%), Ciliophora (6.8%) and Harpacticoida (3.0%) which were also important components of the meiofaunal community. All of these five faunal groups comprised more than 90% of total meiofauna. The highest density of 195 ind./10 $cm^2$ was found at St. 4 (4960 m water depth), but the lowest one, 85 ind./10 $cm^2$ at St. 1 (4969 m water depth). The overall mean density of meiofauna was estimated as $1.34{\times}10^5\;ind./m^2$. The abundance of meiofauna showed a slow decreasing trend along the water depth. The highest density was observed in the upper 1 cm and density decreased drastically with increasing depth from the surface.