• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.10-18
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• 2014

The habitat characteristic of the Gammarus sobaegensis which is one of the Amphipoda kinds has been found inhabiting in the inter mountain stream at Ganseong stream. From the investigation, the main inhabitant area of the G. sobaegensis maintained the water temperature under $10^{\circ}C$ during the spring and autumn season, and the electric conductivity was also maintaining under $40{\mu}Scm^{-1}$. For the precipitation, for this year when the monthly accredited rainfall did not exceed 800 mm, it did not affect maintaining the population of the G. sobaegensis but when the monthly accredited rainfall exceeded 1,000 mm it was found to be working as a unfavorable condition for maintaining the population. The effect especially from this kind of rainfall created the flow of G. sobaegensis as well as the flow of the fallen leaves which are the food resources and affected the population of the G. sobaegensis as a multiple interruption reason. Among the Functional Feeding Groups (FFGs) distribution depending on the use of the food resources the shredders showed up in the ratio of 20% in the site 1~3, and showed a big difference with the site 4~7 as it showed up in the ratio near 10%. Also, after comparing the variation of the individual number among the G. sobaegensis and shredders at the site 1~3 where G. sobaegensis mainly shows up, it showed the same variation pattern except for 2009.

• Korean Journal of Ecology and Environment
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• v.54 no.1
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• pp.39-48
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• 2021

In order to control algal bloom, which causes environmental problems such as eutrophication in freshwater ecological environments, many attempts have recently been made using biological approaches. Among them is filtration using bivalve. Algae control with filter-feeding bivalves is emerging as an eco-friendly method. In this study, bivalves collected at Baekje weir in Geum River in Korea from Jun to Sep 2020 were tested to find out the possibility of algae control using filter-feeding bivalves through laboratory experiments. The Unio douglasiae, Anodonta woodiana, and Anodonta arcaeformis collected from Baekje weir were put into a water tank (2 L) containing Clorella vulgaris, and as a result, the average filtration rate was 95.9% per animal after 24 hrs. Calculating this with the Chl-a concentration converted to a calibration curve, it was found that the average of 154.84 ㎍ L^-1 of Chl-a was reduced. Based on this calculation, the possibility that one bivalve can eliminate Chl-a in one month is 0.0005%. It is expected that the effect is 20.14% when there are 40,000 animals. These results indirectly showed how effective bivalve's ability to control Chl-a in their habitat is. Although this study was limited to calculating the algae control ability of aquatic ecosystem based on the filtration rate of bivalve and the corresponding Chl-a reduction rate, it is thought that it will be used as basic data for integrated research from various factors and viewpoints (phytoplankton, aquatic plants, benthic organisms, and sediments) through additional research.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.601-608
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• 2021

This study surveyed the ecological characteristics of Squalidus multimacultus at Taehwa River tributary Cheokgwa Stream from January to December 2020. The species inhabited the riverbed that was mostly covered with sand. The water depth was 25-164 cm, and the average was rather deep at 68 cm. The stream velocity was slow at 0.21±0.26 (0.16-0.43) m/sec. The gender ratio of females to males was 1:0.99. The age according to the total length-frequency distribution indicated that the group with less than 50 mm (29.4 - 49 mm) in total length was one year old, the group with 50 - 69 mm was two years old, the group with 70 - 89 mm was three years old, and the group over 90 mm was four years old. The total length of sexually mature fishes was 40 mm for both males and females. The spawning season was from July to August, and the water temperatures was 23.8 - 25.4℃ during the period. The prosperous spawning season was August. The average number of eggs in the ovaries was 1,395 (648 - 2,201) per matured female, and the matured eggs were yellowish and spherical with a mean diameter of 0.67±0.24 (0.62 - 0.83) mm. The live foods were of S. multimacultus attached algae, zooplankton, aquatic insects, and Mollusca. The feeding habits of S. multimacultus were omnivorous, but more than 95% of the stomach content was plant-attached algae. The larger the size of this species, the greater the amount and frequency of eating aquatic insects, which were animal feeds. The population that ate aquatic insects did not eat vegetable food.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1551-1559
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• 2013

This study was conducted to compare benthic macroinvertebrate communities of urban stream and nature stream in Daegu-si, Gyeongju-si, Gyeongsan-si, Andong-si, and Cheongsong-gun. The survey was carried out with 12 points in total six points for urban stream, six points for nature stream from Sept. 2011 to July 2012. In the urban stream were 33 species belonged to 24 families, 11 orders, 7 classes and 4 phyla while in the nature stream were 73 species belonged to 38 families, 12 orders, 5 classes and 4 phyla. In general, species diversity indices and species richness indices appeared low in urban stream but dominance indices was high. Functional feeding groups and Habitat Oriented Groups appeared comparatively simple in urban stream rather than nature stream. As a result of analysis of community stability, species included to area I and area III equally appeared in nature stream while species included to area I mostly appeared in urban stream. An analysis of the correlation between the population density and the number of species, the population number and biological indicators such as DI, H', RI, and ESB revealed that there was a significant correlativity with the diversity index and a very high correlativity with the number of species, abundance index and the ESB. On the other hand, the population number and the dominance index did not reveal any correlativity. For indicator species, Hydroptila KUa, Physa acuta appeared in urban stream while Paraleptophlebia chocolata, Epeorus pellucidus appeared in nature stream.

• Korean Journal of Ichthyology
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• v.30 no.1
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• pp.65-68
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• 2018

The anatomical study of the olfactory organ in Liobagrus somjinensis, being related to the habitat environment and ecological habit, was carried out using a stereomicroscopy and digital camera. The paired olfactory organs are situated at the dorsal part of the snout, and consisted of two opening (anterior and posterior nostrils) and the olfactory chamber. The tubular anterior nostril is located between the tip of upper lip and the nasal barbel. The posterior nostril flat to the surface is adjacent entirely to the basement of the nasal barbel. The olfactory chamber has a rosette structure with 22~24 lamellae of linguiform, arranged transversely and radially from the medium raphe. These results may prove that L. somjinensis is dependent on olfaction, related to the hiding, the feeding and the nocturnal lifestyle in rapids.

• Journal of Environmental Science International
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• v.22 no.3
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• pp.309-318
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• 2013

This study was conducted for determining the influence of artificial structures on benthic macroinvertebrate communities in stream. Sampling was taken at upper(pool), down(riffle) and control(riffle) from two check dams, two weirs, one agricultural reservoir, and one multipurpose dam in northern part of Gyeongsangbuk-do. The benthic macroinvertebrate communities of these structures were surveyed during 2009 to 2011. The simple habitat of benthic macroinvertebrates occurred at the upper sites due to pooling effects from artificial structures. Specifically, Check dam1, Jusanji, Imha dam showed very low biological attribute values compared to the down and control sites, which have greater difference in substrate characteristics. However, in the upper sites of Check dam2, Weir1 and Weir2, the difference of values of biological attributes was relatively smaller. Also, proportion of functional feeding groups and functional habit groups were relatively simpler at upper stream and the degree of community differences was greater between upper and down, control sites. Spearman's correlation between biological attributes and substrate characteristics, water quality parameters had significant correlations; particularly, the substrate characteristics were more significantly related. In conclusion, the pool caused by artificial structures had negative effects on benthic macroinvertebrate communities thus leading to simplified stream habitats at upper stream ecosystems.

• Journal of Korean Society on Water Environment
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• v.36 no.1
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• pp.36-47
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• 2020

Three large scale weirs were constructed 2010 - 2011 in the Namhan river, Korea. The purpose of this study was to investigate the spatial distribution of benthic macroinvertebrates and the influence of environmental factors at the weirs 2014 - 2015. The number of species was higher in the riparian zone than in the transition or the limnetic zone. This seems to be because of the diversification of microhabitats and food sources according to the development of littoral zones. From the riparian zone to the limnetic zone, the individual abundance proportion of gathering collectors among functional feeding groups decreased, and that of filtering collectors increased. In the limnetic zone, sprawlers and climbers among habitat orientation groups decreased, and burrowers increased. This means that coarse particulate organic matter originated from land or riparian zone was transformed to fine particulate organic matter in the limnetic zone. Asian clam (Corbicula fluminea) and chironomids were dominant species based on individual abundance. Asian clam, a major taxon considering biomass, was abundant toward the limnetic zone. This is becasue of the shallow depth, suitable water current, slightly coarse substrate, and good water quality. There was no significant relationship between the water quality and the characteristics of the benthic macroinvertebrate community because the water quality was spatially not heterogenous. The more influential factors for benthic community were physical factors, especially water depth. Water depth showed a markedly significant correlation with Shannon-Weaver's species diversity (r=-0.90), Margalef's species richness (r=-0.82), and McNaughton's dominance (r=0.86). Water depth showed a positive correlation (r=0.68) with the Kong and Kim BMSI (Bentic Macroinverebrates Streambed Index), and this may be related to the coarse substrate of the limnetic zone.

• Korean Journal of Ichthyology
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• v.21 no.1
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• pp.28-37
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• 2009

The diet of Pacific cod (Gadus macrocephalus) in the East Sea, Yellow Sea and Jinhae Bay was studied by analysis of stomach contents. In total, 518 individuals ranging from 15.5 to 77.0 cm standard length SL were analyzed. Prey organisms of the Pacific cod in the East Sea consistedof Caridea, Cephalopoda and Pisces, whereas In the Yellow Sea, the main food items of Pacific cod were similar to those of East Sea Pacific cod except for Cephalopoda. Interestingly, the stomach contents of Pacific cod in Jinhae Bay is mainly Pisces, which is in contrast to those of the two different coastal areas, the East Sea and the Yellow Sea. Although various species of food were eaten by smaller Pacific cod, both Caridea and Pisces were mainly taken by larger Pacific cod. Consequently, the diet of Pacific cod within acertain size is mainly influenced by prey abundance and prey-size spectrum in its habitat. Higher stomach emptiness of Pacific cod in Jinhae Bay might indicate that fully matured Pacific cod temporally stop feeding during their spawning period.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.298-310
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• 2021

Freshwater eel Anguilla japonica is a commercially important species in East Asia. However, given the continuously decreasing resources due to many problems as climate change, habitat destruction and overfishing, mass seed production is crucial. In particular, the eel larvae present a unique life history, spending prolonged periods in the Pacific Ocean. Therefore, finding suitable feed that lasts through the long larval stages is rather difficult. In the present study, we histologically observed the development of digestive organs for 50 days after hatching (DAH). The endogenous reserves were completely absorbed at 7 DAH, and the first exogenous feeding started thereafter. The teeth appeared at 4 DAH and dramatically changed from needle-like to broad-based types by 50 DAH. The intestine remained as straight gut until 50 DAH. The intestinal cilia appeared first at 6 DAH and their density continuously increased thereafter. Interestingly, goblet cells appeared in the intestine, but not in the esophagus, where these cells are commonly observed in other teleosts. In addition, high amounts of eosinophil substances, assumed to be zymogen granules, accumulated in the pancreas, suggesting a specific digestive strategy of this species. Overall, these observations largely update the previous reports and can be useful to improve A. japonica seed production.

• Journal of Korean Society on Water Environment
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• v.37 no.3
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• pp.190-203
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• 2021

Water quality, benthic macroinvertebrate communities, and other factors were investigated to explore the effects of the effluent discharge from a sewage treatment plant into Jwagwang stream in Busan in 2019. During the study period, the flow rate of this stream was in the range of 10,400 m³/day to 52,200 m³/day except for the discharge of about 24,000 m³/day of the effluent. After discharge, the flow velocity increased by about 65% and the water depth increased by about 40%. At sites downstream of the discharge point, BOD, COD, TOC, T-N, T-P, and other water quality values were worse than those of the upstream sites. The periphytic algal chlorophyll-a concentrations in the natural substrata were higher than those of the upstream sites, especially in May and August. However, at sites downstream of the discharge point, the individual numbers of Annelida were decreased and individual numbers of the insecta of arthropoda were increased. Also, species numbers and the diversity and dominance indexes were improved in the sites downstream of the discharge point. The functional feeding groups (FFGs) of collector-filterers were increased and the habitat orientation groups (HOGs) of sprawlers, burrowers, and clingers were especially increased at the sites with additional reclaimed wastewater effluent flow. Regardless of the effluent discharge, BMI, an indicator of ecological stream health using benthic macroinvertebrate species, did not show large gaps between the study points. Although the water quality of the sites downstream of the discharge point was much worse than those upstream, their ecosystem soundness was better than those of the upstream sites from an ecological perspective.