• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.1
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• pp.67-82
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• 2008

This study was performed to investigate changes in benthic environment and macrobenthic polychaete communities in Gamak Bay where various environmental quality improvement projects have been implemented in recent years. Field surveys were carried out in February, 2005 and February, 2006 and twenty stations were selected to explore whether or not there were between-year differences in biotic and abiotic variables. Of 10 environmental variables measured, only three variables including dissolved oxygen (DO), total ignition loss (IL), acid volatile sulfide (AVS) showed significant between-year differences. Specifically, IL and AVS were, on average, 1.5 and 3 times lower in 2006 compared to those in 2005, respectively, which was more pronounced in the northern part of the bay. A total of 95 polychaete species was sampled from the two sampling occasions. Between-year differences in the number of species, abundance, and diversity were varied from place to place. In the northern part of the bay, fewer species were found in 2006 rather than in 2005, but diversity increased in 2006 due to the reduction in dominance of a few species. On the contrary, in the central part of the bay, the number of species, abundance and diversity prominently increased in 2006. In the southern part of the bay, all the biological indices maintained similarly during the two years. Dominant species in 2005 were such opportunistic or organic pollution indicator species as Lumbrineris longifolia, Capitella capitata, Mediomastus californiensis, Pseudopolydora paucibranchiata, etc. and most of them were mainly distributed in the northern part of the bay and in the proximity of it. In 2006, however, Euchone alicaudata, L. longifolia, Paraprionospio pinnata, Flabelligeridae sp., etc. were dominant and distributed mainly in the central part of the bay. Multivariate analyses showed that the whole polychaete community could be divided into 5 groups reflecting the geographical positions of the sampling stations and temporal variation particularly in the northern part of the bay. According to the results of BIO-ENV procedure, TOC (${\rho}=0.52$) and AVS (${\rho}=0.49$) as a single variable best explained the polychaete community structure. The best combination was made by such variables as TOC, AVS, sorting coefficient, and water temperature (${\rho}=0.60$). In conclusion, between-year differences in biotic and abiotic variables imply that recent efforts for the environmental improvement produced positive influences on the benthic environment of Gamak Bay, particularly the northern part of the bay.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.619-627
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• 2015

Cyanobacteria were sampled at five sites in the Han River, Nakdong River, and Geum River watershed from June 2014 to May 2015 and then cultivated. Two genera and five species of the cyanobacteria were newly recorded in Korea. The newly recorded species were Limnothrix redekei, Pseudanabaena galeata, Pseudanabaena amphigranulata, Sphaerospermopsis aphanizomenoides, and Calothrix parietina. As a result, the Korean flora of the cyanobacteria now include four orders, 22 families with 73 genera, 143 species, and two varieties, giving a total of 146 taxa.

• Journal of Environmental Science International
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• v.4 no.2
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• pp.105-116
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• 1995

Identified 7 species of the genus Prorocentrum which have been obtained from the southern coast area for 4 years from 1990 to 1994 can be summarized as followed. P.balticum is rare species, causing a red tide, and P.dentatum, P.micans, P.minimum, P.triestinum are cosmopolitan species often causing a red tide in the study area. P.gracile and P.lima are very rarely showed up, the former is recorded at first in domestic and later is benthic attached species which has diarrheic shellfish poison.

• Ocean and Polar Research
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• v.28 no.2
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• pp.67-78
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• 2006

Six surface sediments from two offshore transects of Ulsan and Gampo, on the southeastern margin of Korea were taken for sediment and foraminiferal analyses. Sedimentary processes are dominated by reworking and resedimentation from storms in the area off Ulsan and hemipelagic suspension settling in the area off Gampo. Eighty-four foraminiferal species were identified in total assemblages, including 33species of living populations and 9 species of planktonic foraminifera. The characteristics of foraminifera showed differences of offshore environments between Ulsan and Gampo. The number of living species, species diversity and equitability in Gampo offshore area had higher values than those in Ulsan offshore area. However, planktonic/benthic(P/B) ratio showed higher in the Ulsan offshore area. The species diversity indices and P/B ratio indicated that environmental stability and surface-ocean productivity in the Gampo offshore area were relatively higher than the Ulsan offshore area. The difference of species compositions is useful for interpreting the paleoenvironments in mud deposits of the southeastern margin of Korea.

• Ocean and Polar Research
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• v.23 no.4
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• pp.433-440
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• 2001

Marine organisms in Antarctica live in an environment which exhibits variability in physical processes over a wide range of temporal scales, from seconds to millennia. This time scale tends to be correlated with the spatial scale over which a given process operates, though this relationship is influenced by biology. The way organisms respond to variability in the physical environment depends on the time-scale of that variability in relation to life-span. Short-term variations are perceived largely as noise and probably have little direct impact on ecology. Of much greater importance to organisms in Antarctica are seasonal and decadal variations. Although seasonality has long been recognised as a key feature of polar environments, the realization that decadal scale variability is important is relatively recent. Long-term change has always been a feature of polar environments and may be a key factor in the evolution of the communities we see today.

• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.199-209
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• 1999

Before investigating the long-term variations in macrobenthic communities sampled in the Chokchon macrotidal flat in Inchon, Korea, from 1989 to 1996, we need to understand how environmental factors in the area vary. As potential governing agents of tidal flat communities, abiotic factors such as mean sea level, seawater, air temperature, and precipitation were considered. Data for these factors were collected at equal intervals from 1976 or 1980 to 1996, and were analyzed using a decomposition method. In this analysis, all the above variables showed strong seasonal nature, and yielded a significant trend and cyclical variation. Positive trends were seen in the seawater and air temperatures, and based upon this relationship, it was found that the biological sampling period of our program has been carried out during warmer periods in succession. This paper puts forth some hypotheses concerning the response of tidal flat macrobenthos communities to the changing environment including mild winters in succession.

• Environmental Engineering Research
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• v.24 no.4
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• pp.638-645
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• 2019

This research was an evaluation of the fish fauna and the habitat for Brachymystax lenok tsinlingensis (B. lenok tsinlingensis) for 11 stations at the Bonghwa-gun sanctuary. The predominant species in this research area was Zacco koreanus. B. lenok tsinlingensis, which has been designated as an endangered freshwater fish in Korea, was found in the Bonghwa sanctuary zone, except at stations 5 and 6. The B. lenok individuals were shorter in length than 400 mm. In total, 13 endemic species were found, including Coreoleuciscus splendidus and Iksookimia longicorpus. Specimens of Koreocobitis naktongensis, a first grade endangered species, were also collected. The benthic macroinvertebrates consisted of four divisions, four classes, seven orders, 30 families, 60 species, and 10,344 individuals and were distributed among the orders Ephemeroptera (55.9%), Diptera (18.2%), Trichoptera (12.4%), Plecoptera (2.1%), and Odonata (0.3%).

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.218-227
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• 2011

The objective approach for assessment of stream naturalness is an essential part of the stream restoration project. This study proposes the methodology for the assessment of stream naturalness considering physical, biological and chemical factors. Physical factors consists of riffle and pool, river bed material, bank protection, floodplain vegetation and levee materials; biological factors are benthic macroinvertebrate, KSI (Korean Saprobic Index), and IBI (Index of Biological Integrity) and chemical factors are pH, DO (dissolved oxygen), and TP (total phosphorus). This procedure is applied to the Mokgamcheon. As a result, the downstream of Mokgamcheon (zone I) needs the prompt improvement of stream naturalness, compared to the others (zone II and III). This evaluation technique will be an effective tool to quantify the stream naturalness and can be used to set the target of stream restoration project.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.129-138
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• 2012

We investigated an ecological impact of drought simulated by discharge depletion on the water quality and benthic diatom community in the indoor experimental channel. As artificial substrates slide-glass was installed in acrylic channel for 16 days. Channels were supplied continuously with eutrophic lake water with a discharge rate of 6 L $min^{-1}$ in duplication during the colonized period. And then during the discharge depletion period, three discharge rates were provided: NDF (No depletion of flow rate (Control): 6 L $min^{-1}$), LDF (Low depletion of flow rate: 3 L $min^{-1}$) and HDF (High depletion of flow rate: 1 L $min^{-1}$). Environmental factors in the water, such as suspended solid, Chl-$a$ and nutrients concentration, were measured with periphytic algae including AFDM (ash free dry matter), Chl-$a$ concentration and cell density at 1-day intervals. Light intensity increased significantly with discharge depletion (F=229.5, p= 0.000). $NH_4$-N concentration was highest at HDF. Suspended solid in outflowing water decreased at HDF (88%), LDF (97%) and NDF (99%), compared to inflowing water (100 %). Chl-$a$ in substrates increased more than two times at LDF and HDF than NDF (F= 8.399, p=0.001). Also AFDM and benthic diatom density increased significantly at LDF and HDF than NDF (F=9.390, p=0.001; F=6.088, p=0.007). In all experimental groups, $Aulacoseira$ $ambigua$, $Achnanthes$ $minutissima$ and $Aulacoseira$ $granulata$ were dominant species accounting for greater than 10% of benthic diatom density. The most dominant species, $A.$ $ambigua$ was highest at LDF, followed by HDF and NDF (F=8.551, p=0.001). In conclusion, the effect of drought simulated by discharge depletion in an artificial stream ecosystem caused significant changes on water quality and benthic diatom biomass. This result provides a useful data to understand the effect of draught on stream ecosystem in situ.

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.105-117
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• 2019

In order to investigate the characteristics of benthic macroinvertebrate communities in the Gihwa stream, a tributary of the Dong River, we surveyed the community and environmental factors in April and November 2013 at 6 sites. The benthic macroinvertebrate taxa represented total 63 species belonging to 29 families, 12 orders, 5 classes and 4 phyla. Total 48 (10~28 in each site) species were collected in April and 44 (13~24 in each site) in November. The number of individuals increased slightly from $560{\sim}2,290m^{-2}$ in April to $806{\sim}3,674m^{-2}$ in November. Chironomidae spp. was dominant species in April and Stenopsyche bergeri was dominant species in November. In the Functional Feeding Groups, Gathering-collector(53.9%) was dominant in April, while Filtering-collector (44.3%) increased in November. Intolerant order category (i.e. EPT species richness) in St.1, St.5 and St.6 increased in November compared to April due to the increase of Trichoptera. St.2, St.3 and St.4, which were located near the fish farm, were low EPT as a whole, but Benthic macroinvertebrate index (BMI) was good state in November than April due to decrease of Chironomidae spp.. The environmental factors in the survey site showed similar tendency except for St.1 between both seasons, and electrical conductivity, salinity, and water width showed seasonal differences. Cluster analysis and Nonmetric multidimensional scaling (NMDS) based on benthic macroinvertebrate community data were divided into two groups according to season. Electrical conductivity, salinity and substrate composition were the most influential factors determining the distribution patterns of macroinvertebrate communities.