• Korean Journal of Environment and Ecology
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• v.26 no.5
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• pp.694-706
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• 2012

The purpose of this study was to offer the raw data for conservation and restoration of aquatic ecosystem by surveying and analysing a water quality, sediment, benthic macroinvertebrate, fish and hydrophyte in Junam reservoir. In the result of analysing the water quality, pH was 8.2~8.4, 6.0~7.5mg/${\ell}$ in COD, 10.0~10.3mg/${\ell}$ in SS, 8.3~11.5mg/${\ell}$ in DO, 0.1mg/${\ell}$ in T-P and 1.2~1.3mg/${\ell}$ in T-N. In case of the sediments, Cd was 0.47~0.52mg/kg, 7.08~7.43mg/kg in Cu, 0.22~0.32mg/kg in As, 0.02~0.03mg/kg in Hg, 6.20~7.45mg/kg in Pb, 32.80~39.70mg/kg in Ni, 513.0~543.0mg/kg in F and 137.0~140.0mg/kg in Zn. $Cr^{6+}$ was not detected. The benthic macroinvertebrates were 432 individuals including 3 phyla, 5 classes, 9 orders, 26 families, 33 genera and 39 species, and the ecological score of benthic macroinvertebrate community(ESB) was 25. The fishes were 8 families and 14 species, and the invasive alien species were 2 taxa including Micropterus salmoids and Lepomis macrochirus. The hydrophytes were 63 taxa including 28 families, 42 genera, 56 species, 1 subspecies and 6 varieties. The emergent plants were 38 taxa(60.3%), 5 taxa(7.9%) in floating-leaved plants and each 10 taxa(15.9%) in free-floating plants and submerged plants.

• Korean Journal of Ecology and Environment
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• v.53 no.3
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• pp.286-294
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• 2020

The Chironomus(Diptera: Chironomidae) is a freshwater benthic invertebrate that is an important indicator organism used for environmental pollution and water quality monitoring. In this study, we performed morphological classification and genetic species identification using the cytochrome c oxidase subunit I (COI) gene on mitochondrial DNA for an accurate species classification of Chironomus larvae found in tap water purification plants in Incheon, Korea. Twenty larvae in six water purification plants consist of four species, including twelve Chironomus kiiensis, six Chironomus flaviplumus, one Chironomus dorsalis, and one Polypedilum yongsanensis (not included Genus Chironomus). Morphological characteristics of each larvae were identified based on the head capsule, the mentum, the mandible, the antenna, and the claw. Based on the COI sequences of 21 individuals of 17 Chironomus species registered in NCBI Genbank, phylogenetic analysis indicated that the 20 individuals investigated in this study consist of the same clade with corresponding species of the high homology (99~100%) including C. kiiensis, C. flaviplumus, C. dorsalis, and P. yongsanensis. These results will be used as main classification indicator for monitoring freshwater ecosystems by providing integrated morphological and genetic information for the species identification of Korean Chironomus.

• Ocean and Polar Research
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• v.23 no.2
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• pp.109-119
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• 2001

Meiobenthic community structure of tidal flats near the Yeonggwang Nuclear Power Plant have studied during summer (June) and fall (October) 1997. Examination of sediment samples collected along the transects showed that there were 18 different types of meiobenthos in the study area. The most abundant meiobenthic animals belonged to Phylum Nematoda in both seasons and all transects. However, sediment samples collected near discharge areas, transects A and B, showed relatively lower abundance than other general coastal areas. Another abundant meiobenthic organism is benthic Harpacticoids which is very sensitive to any environmental changes. Polycheats and Ostracods were next abundant meiobenthos which also showed the difference between the study area and other general coastal areas. Only transect C maintained similar meiobenthic abundance and diversity to other coastal areas. Horizontal distribution for transects A and B showed higher densities in upper and mid tidal flat zones. On the other hand, transect C which is located furtherest from the discharges showed an increasing trend in abundance from upper to lower areas. For size distribution analyses showed that animals which fit into the meshsize of 0.125 mm were abundant, Vertical distribution of meiobenthic animals within the sediments for both sampling seasons showed the highest individual numbers in the surface sediment layers of 0-1 cm depth and showed a decreasing trend as sediment gets deeper. Each class of meiobenthos had different vertical profiles. When comparing survey transects A and B with other similar tidal flat areas, this sites seems to a very unstable environment of tidal flats near the Yeonggwang Nuclear Power Plant.

• Korean Journal of Ecology and Environment
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• v.52 no.1
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• pp.13-20
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• 2019

Heavy metals resulted from the increase of human industrial activity are introduced into the environment through rainfall and wastewater, and have harmful effects on inhabitants. In this study, we investigated biological responses such as survival rate, growth rate, emergence rate and sex ratio, and morphological effects of mentum deformity in Chironomus plumosus, an indicator organism to evaluate pollutions on aquatic ecosystem. The survival rate of C. plumosus showed time- and dose-dependent decrease after chromium and copper exposures. Growth rate decreased at $4^{th}$ day after chromium exposure and significantly reduced at exposure to relatively high concentration (copper $1000mg\;L^{-1}$) for all exposure times. In addition, we observed that the emergence rate by exposure to copper $1000mg\;L^{-1}$ was significantly lower than that of the control group. The imbalance of sex ratios showed at relatively low concentrations (chromium 10 and $50mg\;L^{-1}$) with the high proportion of female and at the relative high concentration (copper $1000mg\;L^{-1}$) with the high proportion of male. Furthermore, the morphological mentum deformities of C. plumosus observed in the exposed group according to chromium and copper exposure. These results suggest that the heavy metal exposure in environment may influence biosynthetic and morphological stresses of benthic invertebrate C. plumosus, and aquatic midge C. plumosus are potential indicators for toxicity assessment of heavy metals such as chromium and copper.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.4
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• pp.349-362
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• 1999

To understand the role of protozoa in the early formation of microbial fouling community, the studies on the formation of microbial film, the succession of microbial fouling communities, and the grazing pressure on bacteria population in microbial film were carried out in the laboratory, Inchon outer port and Inchon inner harbour. Bacteria and heterotrophic flagellates formed primary microbial film on the aluminum surface within 6 hours and oligotrich ciliates were observed 2 cells $mm^{-2}$ on the same surface at 9 hours in Inchon inner harbour which had physically stagnant condition. The larvaes of Balanus albicostatus which were dominant meiobenthos in Inchon coastal area attached on the glass surface at the first day of experiment. Heterotrophic flagellates showed maximum abundance of 465 cells $mm^{-2}$ at the 13rd day and ciliates showed maximum abundance of 63 cells $mm^{-2}$ at the 11st day in the Inchon inner harbour. In the Inchon outer port which opens to the outer sea, the maximum abundance of protozoa occurred at early phase, but not so many. The dominant heterotrophic flagellates were Metrornonas simplex and Bodonids. Dominant ciliates were small tintinnids and oligotrich ciliate Strombidium sp., Large Strombidium (oligotrich ciliate) and sessile Acineta turberosa (suctorian ciliate) occurred after 10 days. The attached larvae of Balanus occurred as biofouling organism on the early surface and showed maximum abundance of 18 indiv. $cm^{-2}$ at 7th day. At that time, adult barnacles were observed on the surface and dead barnacles were observed after two days. Except barnacles, the larvaes of Anthozoa sp., Oysters (Crassostrea gigas) and Polychaeta were observed on the surface from 3rd day. 3 benthic copepods including Harpacticus sp., I isopod, 1 polychaeta and 1 gastropoda were observed as predators of the microbial film on the surface after 7 days when microbial film developed very well. Although the ingestion rates of protozoa on the bactctia of the rnicrobi31 film were relatively low, the average grazing rate of protozoa on bacteria was high of 0.058 $h^{-1}$. This implied that the grazing pressure of protozoa influences the mortality of bacteria populations on the microbial film. but protozoa cannot get enough energy from only bacteria on the microbial film.

• The Korean Journal of Malacology
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• v.29 no.1
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• pp.51-63
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• 2013

To assess the effect of environmental factors on the sustainability of cultured production shellfish, we investigated the habitat characteristics of tidal flat (Namhae-po in Taean). We measured the physiochemical parameters (temperature, salanity, pH, dissolved oxygen and nutrients) and the geochemical characteristics (chemical oxygen demand, ignition loss, C/N ratio and C/S ratio). Surface sediments were collected from several site of tidal flat to examine the geochemical characteristics of both the benthic environment and heavy metal pollution. The grain size for research area of tidal flat were similar at the ratio of silt and clay in comparison with the other site of it. The C/N ratio was more than 5.0, reflecting the range arising from the mix of marine organism and organic matter. The C/S ratio (about 2.8) showed that survey area had anoxic or sub-anoxic bottom conditions. The enrichment factor (Ef) and index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. Adult surf clam (Mactra veneriformis) density was highest at St. 2 (middle part of the Namhae-po), on the other hand, surf clam spat density was highest at St. 3 (lower part of the Namhae-po). Heavy rain, terrigenous suspended clay with fresh water from neighboring agricultural land, and severe high air temperature during summer could be thought as detrimental causes of spat and adult mortality in Namhae-po tidal flat. We suggested that the growth of shellfish in the tidal flat was effected by the various environmental conditions, so an improvement in the cultured method was needed.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.179-191
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• 2019

Heavy metals in stream water and sediments around industrial complex were studied in order to assess the contamination and to identify the potential source of metals. High variability has been observed for both dissolved and particulate phases in stream water with coefficient of variation (CV) ranging from 1.3 to 2.8. The highest metal concentrations in both phases were observed in Gunja for Ni and Cu, in Jungwang for Zn and Pb and in Shiheung for Cd, respectively. These results indicate that the different metal sources could be existing. The concentrations of the heavy metals in sediments decreased in the order of Cu>Zn>Pb>Cr>Ni>As>Cd>Hg, with mean of 2,549, 1,742, 808, 539, 163, 17.1, 5.8, $0.07mg\;kg^{-1}$, respectively. Mean of metal concentrations(except for As) in sediments showed the highest values at Shiheung stream comparing with other streams. In sediments, the percent exceedance of class II grade that metal may potentially harmful impact on benthic organism for Cr, Ni, Cu, Zn, Cd, Pb was about 57%, 62%, 84%, 60%, 68%, 81% for all stream sediments, respectively. Sediments were classified as heavily to extremely polluted for Cu and Cd, heavily polluted for Zn and Pb, based on the calculation of Igeo value. About 59% and 35% of sediments were in the categories of "poor" and "very poor" pollution status for heavy metals. Given the high metal concentrations, industrial wastes and effluents, having high concentrations of most metals originated from the manufacture and use of metal products in this region, might be discharged into the stream through sewer outlet. The streams receive significant amounts of industrial waste from the industrial facilities which is characterized by light industrial complexes of approximately 17,000 facilities. Thus, the transport of metal loads through streams is an important pathway for metal pollution in Shihwa Lake.