• Journal of Environmental Science International
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• v.27 no.11
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• pp.1117-1127
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• 2018

This study was carried out to gather basic data for the purpose of proposing a plan to improve the water quality and conserve the aquatic ecosystem of the Singu Agricultural Reservoir in Korea. The water quality, sediment composition, benthic macroinvertebrate distribution, and fish distribution in the Singu Reservoir were analyzed; the reservoir is located close to farmlands, forests, villages, and livestock breeding areas. The results of the water quality analysis are as follows: 5.8~7.8 mg/L for dissolved oxygen, 13.1~20.7 mg/L for chemical oxygen demand, 14.4~18.8 mg/L for suspended solid, 0.96~1.70 mg/L for total nitrogen, 0.07~0.11 mg/L for total phosphorous, and $41.9{\sim}49.8{\mu}g/L$ for $chlorophyll-{\alpha}$. In total, 75 benthic macroinvertebrate specimens belonging to 4 classes, 7 orders, 14 families, and 17 species were recorded. The ecological scores of the benthic macroinvertebrate communities ranged from 11 to 23. Fish specimens recorded belonged to two families and four species. The dominant fish species were Carassius auratus and Pseudorasbora parva, both of which are water-pollutant tolerant species.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.760-768
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• 2011

Jinwi Stream is considerably polluted. The urban development in a Jinwi Stream basin can make state of aquatic ecosystem worse. However, researches for aquatic ecosystems in Jinwi Stream are insufficient. In this study, biotic indices of periphytic diatoms (DAIpo and TDI), benthic macroinvertebrates (EPT, KSI and ESB) and fish (IBI) were compared with the annual water quality data. Benthic macroinvertebrates indices showed highly significant correlations with concentrations of organic materials and nutrients, while DAIpo, TDI and IBI showed low correlations with them. In particular, ESB can be considered as an useful indicator that reflects the degree of diversity and abundance of biotic community as well as water quality. In polluted and disturbed streams as Jinwi Stream, DAIpo, TDI and IBI appeared to be not available for evaluating and discriminating the water quality, although they have been known as good indices in general streams.

• ALGAE
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• v.36 no.2
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• pp.91-109
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• 2021

The occurrence of benthic dinoflagellates, many of which are known to be toxic, is a critical concern for scientists, government officers, and people in the aquaculture, dining, and tourism industries. The interest in these dinoflagellates in countries with temperate climate is increasing because tropical or subtropical species introduced into temperate waters by currents are able to survive the winter season in the new environment owing to global warming. Recently, several species from the benthic dinoflagellate genera Amphidinium, Coolia, Ostreopsis, Gambierdiscus, and Prorocentrum have been reported in the waters of the South and East Sea of Korea. The advent of the benthic dinoflagellates in Korean waters is especially important because raw or slightly cooked seaweeds, which may harbor these benthic dinoflagellates, as well as raw fish, which can be potentially intoxicated by phytotoxins produced by some of these benthic dinoflagellates, are part of the daily Korean diet. The recent increase in temperature of Korean coastal waters has allowed for the expansion of benthic dinoflagellate species into these regions. In the present study, we reviewed the species, distribution, and toxicity of the benthic dinoflagellates that have been reported in Korean waters. We also provided an insight into the ecological and socio-economic importance of the occurrence of benthic dinoflagellates in Korean waters.

• Economic and Environmental Geology
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• v.56 no.2
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• pp.185-199
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• 2023

This study aimed to predict the effects of water ecology on the supply of hydrothermal energy to model a housing complex in Eco Delta Smart Village in Busan. Based on the results, engineering measures were recommended to minimize problems due to possible temperature variations on the supply of hydrothermal energy from the river. The current distribution of fish, benthic macroinvertebrates, and phytoplankton in the Pyeonggang Stream was monitored to determine their effects on water ecology. In the research area, five species and three families of fish were observed. The dominant species was Lepomis macrochirus, and the subdominant species was Carassius auratus. Twenty-five species and 21 families of benthic macroinvertebrates were found. The distribution of aquatic insects was poor in this area. The dominant species were Chironomidae sp., Lymnaea auricularia, Appasus japonicus, and Caridina denticulata denticulata in February, May, July, and October. Dominant phytoplankton were Aulacoseira ambigua and Nitzschia palea in February and May. Microcystis sp. was dominant in July and October. The health of the ecology the Pyeonggang Stream was assessed as D (bad) according to the benthic macroinvertebrate index (BMI). Shifts in the location of the discharge point 150 m downstream from intake points and discharge through embedded rock layer after adding equal amounts of stream water as was taken at the beginning were suggested to minimize water temperature variations due to the application of hydrothermal energy. When the scenario (i.e., quantity of water intake and dilution water, 1,600 m³/d and water temp. difference ±5 ℃) was realized, variations in water temperature were assessed at -0.19 ℃ and 0.59 ℃ during cooling and heating, respectively, at a point 10 m downstream. Water temperatures recorded at -0.20 ℃ and 0.68 ℃ during cooling and heating, respectively, at a point 10 m upstream. All stream water temperatures after the application of hydrothermal energy recovered within 24 hours. Future work on the long-term monitoring of ecosystems is suggested, particularly to analyze the influence of the water environment on hydrothermal energy supply operations.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.934-942
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• 2010

Bentic macroinvertebrate and fish fauna were investigated from September 2008 to October 2009 in the middle reach of the Suyoung river in Busan. During the survey period benthic macroinvertebrates were collected total 35 species at the three sites (Hanmul-gyo, Dongcheon-gyo, Seokdae Jct.) of Suyoung river. At that sites, species diversity index was 1.9, 1.5, 1.6, dominance index was 0.75, 0.81, 0.86 and Korean Saprobic Index (KSI) was 1.8(B), 4.4(D), 4.4(D) on average, respectively. Dominant species was Caenis Kua, Chironomidae sp., at Hanmul-gyo site and Limnodrilus gotoi, Chironomidae sp., at Dongcheon-gyo and Seokdae Jct. sites. Fish fauna was also investigated at the two sites (Hanmul-gyo and Seokdae Jct.) of Suyoung river. Total caught fishes were 10 species 32 individuals in the first survey and 6 species 26 individuals in the second survey. Dominant species was Carassius auratus in the both surveys. Index of Biological Integrity (IBI) value was C grade at the Hanmul-gyo and D grade at the Seokdae Jct.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.4
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• pp.235-246
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• 2002

The fish farming using net cages has been developed in many semi-closed bays in the southern coast of Korea for the last two decades. The intensive cage cultures of fishes generate considerable amounts of organic waste in the form of uneaten food and faeces. In order to evaluate the effect of fish farming activities we collected the benthic macrofauna near the fish farm area located in Wolho Islet of Gamak Bay and in Haklim Island of Tongyeong in November 1998. Benthic macrofaunal assemblages showed dramatic changes in species number, species diversity, and faunal abundance in the region of the fish farm. These changes were clearly observed even at a distance of up to 30 m from the fish farming cage area. Within 5 m from the cage, there was a zone with low species diversity and highest density, dominated by opportunistic polychaete worm, Capitella capitata. By a distance of 15-30 m, this zone presents highest species number and higher density. Our results clearly demonstrated that fish farm area was highly enriched with organic materials, and implied that the fish farm industry and adjacent benthic ecosystem in semi-closed bay will be seriously damaged by self produced organic wastes in the near future.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.154-165
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• 2013

The species composition of the fish community was studied in four streams where fish kills have previously occurred in recent years; Worun Stream, Seo Stream, Jangnam Stream, and the Anyang Stream. The number of fish species varied from 22 to 86% compared to the number of fish species pre-fish kill. The recovery of fish populations in the streams seems to be determined by water quality and the presence of artificial structures in the streams. The Jangnam Stream, where alkaline pH caused a fish kill, showed a high recovery of fish species due to improvements in water quality. Anyang Stream had a low number of species, possibly because dissolved oxygen concentrations were intermittently low. Artificial structures in streams had a negative impact the recovery of fish species, particularly for benthic fish species. It appears that fish populations can recover rapidly when water quality improves or the movement of fish community is unimpeded. However, water quality and artificial structures in many streams in Korea still present adverse conditions for fish survival, deterring the recovery of fish populations. To conserve fish populations in streams, habitat all owing unimpeded movement for fish and controls on pollutant inputs are needed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.943-953
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• 2021

The purpose of this study is to investigate sediment recovery after the relocation of fish cage farms, by examining the changes in sediments and the benthic polychaete community. A preliminary survey was carried out in October 2017, before the relocation of the farms, and monthly surveys were conducted from November 2017 to October 2018 after the farms were moved. Subsequently, it was conducted every 2-3 months until October 2020. The survey was carried out at three stations (Farm1-3) at the location of the removed fish farms and at three control stations (Con1-3) without farms. The overall organic carbon content of the farm stations was higher than the control stations, but it gradually decreased after the farm was demolished, and there was no statistically significant difference about one year after the relocation of the farms (p<0.05). In the benthic polychaete community, abiotic community appeared at the farm stations in the summer, and consequently, the community transitioned to a low-diversity region with the predominant species Capitella capitata, which is an indicator of pollution. Until the abiotic period in the summer of the next year, the species diversity increased and the proportion of indicator species decreased, showing a tendency of recovering the benthic polychaete community, and these changes were repeated every year. In this study, the abiotic community appeared every year owing to the topographical characteristics, but as the survey progressed, the period of abiotic occurrence became shorter and the process of community recovery progressed expeditiously. Biological recovery of sediments after the relocation of the fish farms is still in progress, and it is imperative to study recovery trends through continuous monitoring.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.735-745
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• 2022

In this study, a health assessment was conducted using the Benthic Health Index (BHI) to assess fish cage farms, where a fishery environment assessment was also performed. A total of 43 farms were evaluated located in the East Sea, West Sea, and South Sea in Korea. The results of the BHI health evaluation included 8 grade 1 farms, 4 grade 2, 12 grade 3, and 19 grade 4. The grade 1 farms included sandy sediment farms and those with low intensity aquaculture, while the grade 2 farms included those located in areas with active seawater circulation. The fish cage farms belonging to grade 3 and 4 included the majority of farms with high-intensity aquaculture activities. There was no significant difference in total organic carbon between grade 3 and 4 farms, but the results of polychaete community analysis show that organic matter concentration was significantly higher in grade 4 farms.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.56-62
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• 2009

Stable carbon isotope analysis was used to investigate the autotrophic carbon sources supporting fisheries in three coastal bay systems of the southern coast of Korea. Carbon isotope ratios (${\delta}^{13}C$) of 31 fish species were analysed and compared with those of a range of potential primary food sources [e.g., seagrass (Zostera marina), seagrass epiphytes, benthic microalgae, macroalgae, marine particulate organic matter (marine POM), marsh plant (Phragmites australis) and terrestrial POM]. ${\delta}^{13}C$ values (range, -16.2${\sim}$-8.3‰) of fishes from the coastal embayment systems were overlapped with those of seagrass (-8.3${\pm}$1.9‰), seagrass epiphytes (-12.4${\pm}$0.6‰), benthic microalgae (-15.4${\pm}$1.6‰) and macroalgae (-16.0${\pm}$1.8‰). In addition, fishes (-12.9${\pm}$1.5‰) from the study area had distinctly higher ${\delta}^{13}C$ values compared to those collected in offshore sites (-17.3${\pm}$0.8‰) of the southern sea of Korea and Nakdong River (-23.2${\pm}$1.6‰). This result indicates that carbon supporting fish communities of these coastal bay systems is mainly derived from the local benthic producers.