• 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.

• Animal Systematics, Evolution and Diversity
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• v.22 no.1
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• pp.29-35
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• 2006

Two ciliates of suborder Euplotina collected from the two habitats (estuarine littoral and sewage treatment plant) in Ulsan, Korea were Euplotes charon ($M\ddot{u}ller$, 1773) and Diophrys oligothrix Borror, 1965. These two species are reported for the first time from Korea. The description was based on the observation of living and silver impregnated specimens. Diagnostic characteristics of these species are as follows. E. charon: size in vivo about $90-130\times65-80{\mu}m$, adoral zone of membranelles over 79.5% of cell length with 54-80 adoral membranelles; right margin of the peristome shaped sinusoidal form and passed through adoral zone of membranelles; buccal cavity wide anteriorly; 10 frontoventral, 5 transverse, 4 caudal cirri, 12 dorsal kineties, mid-dorsal kinety with 21 -25 dorsal bristles; silver-line system double-eurystomus type. D. oligothrix: size in vivo about $80-90\times30-70{\mu}m$; body shape ovoid with prominent right concave posterio-lateral end, two irregular elongated macronuclei with one micronucleus, respectively; 7 fronto-ventral, 5 transverse, 2 left marginal and 2 caudal cirri, 4 dorsal kineties with prominent bristles about $9-14{\mu}m$ long in vivo.

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.31-38
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• 2005

Diel change in urea decomposition activity of epiphytic algae on Phragmites stems and phytoplankton in a shallow littoral reed zone in the south basin of Lake Biwa was investigated with an in situ technique using $^{14}C$-labelled urea. The daily rates of urea decomposition (sum of urea carbon incorporation rate and $CO_2$ liberation rate) by epiphytic and planktonic algae were calculated as 180 ${\mu}$ mole urea surface shoot area $m^{-2}\;day^{-1}$ and 210 ${\mu}$ mole urea $m^{-3}\;day^{-1}$. The chlorophyll a specific urea decomposition rates of epiphytic and planktonic algae were 4.7 to 6.4 and 4.4 to 6.2 ${\mu}$ mole urea mg chl. $a^{-1}$ incubation $time^{-1}$ in daytime and 4.2 to 5.7 and 2.4 to 3.5 ${\mu}$ mole urea mg chl. $a^{-1}\;time^{-1}$ in nighttime, respectively. High values were obtained during 12:00 ${\sim}$ 18:00 and low values during 00:00 ${\sim}$ 06:00 for both epiphytic and planktonic algal communities. A clear diel periodicity in the urea decomposing activity of the planktonic algae was observed. The activity of the epiphytic algae, on the other hand, showed no destinctive variation during a day. The present results indicate that epiphytic algae are one of the significant urea decomposers in a reed zone, and that the diel patterns are quite difference between both algal communities.

• Journal of Ocean Engineering and Technology
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• v.30 no.6
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• pp.498-504
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• 2016

In this study, to predict the effect of beach nourishment at Haeundae Beach, the waves and wave-induced currents were compared before and after beach nourishment using the XBEACH model. Representative wave conditions were determined for the data observed during 2014 (KHOA). Then, the Hs,max and Hs,1/10 values, and their prevalent directions, were used in the numerical modeling input data. A variable grid system was used for the $5km{\times}2.5km$ model areas, and irregular waves based on the JONSWAP spectrum were given as incident wave conditions. In the summer season, eastward wave-induced currents were developed along the beach by the incident wave direction. Before the beach nourishment, the maximum speed around the surf zone was 1.2-1.5 m/s in the central zone of the beach, whereas the maximum speed increased to 1.4-1.6 m/s at the same areas when the currents toward Mipo Harbor were blocked as an effect of the groins after the beach nourishment. In the winter season, westward wave-induced currents were developed along the beach by the incident wave direction. After the beach nourishment, the maximum current speed increased slightly around the surf zone in the central area of the beach, and the littoral current speed decreased at the submerged breakwaters located at Dongbaek Island. As a result, after the beach nourishment, the maximum wave-induced currents increased about 10% in the surf zone of the central area of the beach.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.676-682
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• 2007

The bacterial number, extracellular enzyme activities and structure of bacterial community which are major constituent of aquatic ecosystem within the artificial vegetation island (AVI) were compared to those of the nearby pelagic lake waters in order to evaluate the possibility of the AVI as a eco-technological measure for water quality improvement and restoration of littoral zone in man-made reservoirs. There was not a significant difference in the total number of bacteria, but the number of active (viable) bacteria within the AVI was about 0.7 to 4.1 times higher than nearby pelagic lake water. The ratio of the number of active bacteria versus the total number of bacteria was also higher in the AVI than nearby pelagic lake water. The activities of ${\beta}$-glucosidase and phosphatase were 1.0 to 13.1 and 0.8 to 7.3 times higher respectively in the AVI than nearby pelagic lake water, showing that microorganisms were more active within the AVI. The bacterial communities of the two waters, examined by FISH method, did not indicate a clear difference in the springtime when the growth of macrophytes was immature, but during summer and fall it showed a clear difference indicating the formation of distinct bacterial community within the AVI compared to nearby lake water. From the results of this study, we conclude that AVI can contribute to make up the littoral ecosystem which show rapid cycling of matters through active detritus food chain in the dam reservoirs which have unstable aquatic ecosystem due to short hydraulic residence time and to strengthen the self-purification capacity of the lake.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.502-506
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• 2005

2003년 11월과 2004년 4월의 2회에 걸쳐 상용조류발전소 건설 예정지인 울돌목에서 발전소 건설로 인해 야기될 주변생태환경의 변화를 파악하기 위해 4개 지점의 주변 암반조간대에 형성된 기존의 부착생물상 조사가 수행됐다. 울돌목 주변의 암반조간대에 형성된 부착생물상은 서식 형태에 따라 크게 대형해조류(Macroalgae)를 포함한 고착생물, 소 이동성 부착동물, 이동성 소형 무척추동물 등으로 구분된다 부착생물상은 서식양상에 있어 각각의 정점별 특이성이 관찰되었으며, 이는 각기 다른 비생물학적 요인에 따라 지역 특유의 서식환경이 조성되어 있음을 시사하는 간접적인 결과로 간주된다. 이같은 지역 간 생물상 차이는 조위에 따른 수직분포 분석결과 주로 중부조간대를 중심으로 형성된 생물상에 따라 대별되고 있음이 발견되었다.

• Journal of Plant Biology
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• v.28 no.3
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• pp.199-206
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• 1985

Antithamnion miharae (Tokida) Itono was investigated in field and laboratory culture. The plant grows in lower littoral zone through out the year in Korea. The gland cells occur scarcely or commonly according to the populations, but the terminal hairs in the female plants are not observed. The structure of vegetative thallus and the reproductive organs in culture are similar to those of field materials, except for the number of gonimoblasts, which become five to six in contrast to one to three of the field. A typical Polysiphonia-type life history is repeated in culture. This species which produces tetrahedral tetrasporangia is markedly distinguished from Antithamnion glandulifera sensu Kylin (=Antithamnionella glandulifera (Kylin) Wollaston) which produces cruciate tetrasporangia, while the plants reported by Dawson (1962) and Wollaston (1971) as A. glandulifera seem to be conspecific with A. miharae by the fact that they have the tetrahedral tetrasporangia in stead of cruciate ones.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.54-61
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• 2001

Changes in methanogenic pathway at low temperature were studied by incubation experiments of sediment slurries from the littoral zone of Reservoir Paldang. Methane production rates in sediment slurries increased exponentially between $5＾{\circ}C$and $45＾{\circ}C$, reached a maximum rate of $7.4\;nmol\;{\cdot}\;g^{-1}\;{\cdot}\;h^{-1}$ at $45＾{\circ}C$, and then declined to low rate. The shift of incubation temperature from high temperature ($30＾{\circ}C$) to lowtemperature ($15＾{\circ}C$) resulted in a decrease of methane production rate and of hydrogen accumulation rate, and the transient accumulation of acetate concentration. Chlorofarm inhibited perfectly methanogenesis and resulted in the accumulation of hydrogen and acetate as immediate precursors for metltane formation at both incubation temperatures of $15＾{\circ}C$ and $30＾{\circ}C$. In terms of equivalent methane which was calculated from the two intermediary metabolites accumulated in absence of methanogenesis, methane production from acetate was accounted for 14% of total methanogenesis at $30＾{\circ}C$ and 75% at $15＾{\circ}C$, respectively. When the high acetate concentrations above 19 mM were added to sediment slurries, methane production was inhibited at the low temperature ($15＾{\circ}C$) . Our results demonstrate that contribution of acetate on methanogenesis increases at low temperature, but this pathway is inhibited by high concentration of acetate. Therefore acetate-utilizing methanogensis appears to be a key reaction at low temperature, and seems to be one of bottlenecks of the low temperature anaerobic degradation of organic matter in littoral sediments of the reservoir.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.212-220
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• 2009

In this study, we analyzed fish compositions and ecological characteristics such as trophic guilds and tolerance guilds in association with water quality characteristics in Masan Reservoir during November 2008. Total number of species were 12 species (6 families) and the dominant species were Zacco platypus, Hemiculter eigenmanni, and Pseudorasbora parva. We found three Korean endemic species and one exotic species, Carassius cuvieri. According to the analysis of ecological indicator characteristics, relative proportion of tolerant and omnivore species was 98% of the total indicating that probably, the fauna was influenced by physical habitat disturbance and physicochemical degradations. Fish distribution analysis along with littoral zone showed that the most fishes (${\sim}$95%) were observed in the littoral zone where emerged macrophytes were well developed. Also, substrate analysis indicated that the most species were found near silt area (11 species, 91.7%), so that the significant differences were found between the substrate types. Analysis of water quality indicated that concentrations of total phosphorus (TP) and chlorophyll-a (ChI-a) as a lake trophic indicator were judged as eutrophic states, respectively and COD as an indicator of organic matter pollution averaged 10.9 mg $L^{-1}$. Based on the water quality, this system were influenced by the nutrient enrichments and organic matter. The degradations of water quality in Masan Reservoir resulted in trophic compositions of fish (increase of omnivore species) and the dominance of tolerant fish. This Monitoring data may contribute changes of fish fauna and compositions in relation to habitat modifications and chemical water quality degradations in the future.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.257-262
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• 2002

Numerical model introduced in this study combines wave refraction-diffraction, breaking, bottom friction, lateral mixing, and critical shear stress and three sub-models for simulating waves, currents, and bottom change were briefly discussed. Simulations of beach processes and harbor sedimentation were also described at the coast neighboring Bangpo Harbor, Anmyundo, Chungnam, where the area has suffered from accumulation of drifting sand in a small fishing harbor with a wide tidal range. We also made model test for the case of a narrow tidal range at Nakdong river's estuary area to understand the effect of water level variation on the littoral drift. Simulations are conducted in terms of incident wave direction and tidal level. Characteristics of wave transformation, nearshore current, sediment transport, and bottom change are shown and analyzed. We found from the simulation that the tidal level impact to the sediment transport is very important and we should apply the numerical model with different water level to analyze sediment transport mechanism correctly. Although the model study gave reasonable description of beach processes and harbor sedimentation mechanism, it is necessary to collect lots of field observation data, including waves, tides and bottom materials, etc. for better prediction.