• Ecology and Resilient Infrastructure
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• v.2 no.2
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• pp.108-117
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• 2015

This study was carried out to assess problems related to legislative regulations and guidelines concerning some biological assessment systems applied to stream corridor in Korea. We comparatively reviewed the law of stream corridors and the guidelines for master plan concerned, and the law of water quality and health assessment criteria for the aquatic ecosystem concerned. Stream environments were not managed effectively due to the absence of detail regulations and the criteria for stream assessment. A biological assessment system was not equivalently integrated within the management of water resources in process implementation of projects resulting from the dualistic management system for stream corridors in Korea. The current biological assessment system was reflected to mainly physical habitats or only oriented to some aquatic species correlated with water quality. This system was also recognized as part of environment impact assessment based on an intensive survey method of most biological taxa. Conclusively rapid and quantitative assessment techniques based on advanced organisms, such as vegetation, fish and birds, etc. should be urgently provided for considering as representative indicators of stream conditions in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.2
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• pp.171-182
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• 2022

The habitat degradation caused by large-scale reclamation leads to devastating impacts, such as fine sediment and mud shrimp Upogebia major settlement on Manila clam Ruditapes philippinarum aquaculture in the eastern Cheonsu Bay tidal flats, Republic of Korea. Despite these impacts, there is a lack of studies on the influence of fine sediments on tidal flats that constitute key mud shrimp habitats. This study provides information on the seawater-sediment environment and the influence of dissolved inorganic nitrogen (DIN) fluctuations depending on mud shrimp burrow hole density. Additionally, it discusses countermeasures for Manila clam habitat management. The results show that mean DIN effluxes in areas with a high-density of burrow holes were up to 4 times (0.12 mmol m^-2 d^-1) higher than those in sites of low-density (0.03 mmol m^-2 d^-1) within the Saho and Songhak-ri tidal flats. To manage interference within the competition zone of Songhak-ri tidal flat, it is important to utilize the settlements of spawning season in all three dimensions. Consequently, additional studies in other tidal flats are essential and research in zones where mud shrimps and juvenile clams coexist will help to determine the priorities in the efficient management of clam aquaculture.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.171-183
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• 2023

Estuarine wetlands, which form a distinctive brackish water zone, serve as important habitats for organisms that have adapted to and thrive in this environment. Nonetheless, excessive development and utilization result in artificial disruptions that alter the distinctive functions and attributes of estuarine wetlands. To collect the basic data for the conservation of estuarine wetlands with excellent ecosystems, we investigated the vegetation distribution characteristics and biota status of the Taehwagang River Estuarine Wetland. Data from vegetation surveys have shown that 25 plant communities of six physiognomic vegetation types, including willow vegetation, lotic and lentic herbaceous vegetation, floating/submerged vegetation. In the upper reaches, where topographical diversity was high, various types of wetland vegetation were distributed. In terms of biodiversity, a total of 696 species, including 7 endangered wildlife species, were identified. Due to good ecological connectivity, tidal rivers are formed, brackish water species including various functional groups are distributed around this section. The inhabitation of various water birds, such as diving and dabbler ducks, were confirmed according to the aquatic environment of each river section. The collection of ecological information of the Taehwagang River Estuarine Wetland can be used as a framework for establishing the basis for conservation and management of the estuarine ecosystem and support policy establishment.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.367-373
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• 2012

Population ecology (Ecological characteristics) of Squalidus japonicus coreanus from the Namhan River(Yangpyeong-gun Yangpyeong-eup Changde-ri), Gyeonggi-do, Korea were investigated from January to December 2011. Short barbel gudgeon inhabits habitats run of the lower river. The stream bed was mostly covered sand. Their current velocities were 0.14~1.38m/sec and depths were 80~120cm. The sex ratio of female to male was 1 : 0.82. It is presumed that the spawning season is from June to July and water temperatures were $18.5{\sim}24.3^{\circ}C$. Sexually matured individuals appeared over the two year of age. Frequency analysis of total length indicated that the group with 34~50mm in total length was one year old, the 51~74mm was two years old, and the group over 75mm was three years old. The average number of eggs in the ovaries was estimated as 1,871 per matured female. Stomach content of S. japonicus coreanus were Cyanophyta, Chlorophyta, Bacillariophyta, Rotatoria, Crustaceae, Copepoda, Ephemeroptera, Diptera, and Nematoda. omnivorous, mainly feeds on benthic invertebrates such as chironomidae larvae.

• Korean Journal of Environmental Biology
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• v.33 no.3
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• pp.352-359
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• 2015

In order to investigate the occurrence of Pectinatella magnifica in Nakdong River, extensive series of sampling was conducted through July to November of 2014. Results revealed that these species show preference to attach themselves on natural substrates over artificial substrates. P. magnifica does not show preference for specified substrates, but itappearthat availability of substrates determines their specific distribution. Considering that most commonly found substrates in Nakdong River were natural substrates such as dead twig, woody plants or aquatic plants, it is possible that high availability of substrates is one of the principal factors which increase the rates of growth and distribution of P. magnifica.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.6
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• pp.107-115
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• 2017

This study illustrated the process of bar structure and vegetation coverage to understand historical changes of riverbed and suppose adaptive management in Tan-chun ecological landscape reserve. The study site that lower reach of the Tan-chun are known as habitats of migratory bird and aquatic species with dynamic riverbed. Aerial photos from 2006 to 2016 and surveyed vegetation data in 2006 and 2016 were used by analysis of landscape changes and comparison of vegetation coverage. Study area is classified into 3 sites (A: straight site, B: meandering site, C: meandering and junction with Yangjae-cheon). The result showed that bar area of A and C sites gradually increased, B site decreased during 10 years. Also, ratio of bar area to vegetation coverage and level of vegetation coverage increased in all sites during 10 years. All sites seem to have experienced the terrestrialization with time. On the other hand, ratio of annual vegetation increased and ratio of perennial vegetation decreased in C site in 2016 compare to 2006. Because area of Japanese Hops (Humulus japonicas) as one type of annual vegetation increased, other vegetation could not grow up by its powerful expandability. It is time to make active adaptive management based on not only continuos monitoring but also revaluation of river conditions in order to enhance habitat quality and quantity in Tan-chun ecological landscape reserve.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.102-111
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• 2009

Turbid storm runoff from intensive highland agriculture area has emerged as the major problem of water quality deterioration in the upstream region of the Han River. High slope of the upland combined with high rate of fertilization and intensive plowing causes high rate of soil erosion, and subsequently high suspended sediment and phosphorus content in the runoff water. The variations of water quality during rain spells were surveyed for two years (2005 and 2006) in the Jawoon Stream that is one of hot spots of intensive horticulture discharging turbid storm runoff. SS and TP showed large increase according to the increase of flow rate, whereas TN and BOD showed less fluctuations. Mean EMCs of SS and TP measured for nine rain events were as high as $207mgSS{\cdot}L^{-1}$ and $0.27mgP{\cdot}L^{-1}$, respectively. The export coefficient of SS and TP per area of cultivated field were calculated as $11,912kgSS{\cdot}yr^{-1}{\cdot}km^{-2}$ and $785kgP{\cdot}yr^{-1}{\cdot}km^{-2}$, repectively, which are significantly higher than reports of other area. It can be concluded that SS and TP in the runoffs were high enough to impose major threat to aquatic habitats, and the highland agriculture should be the main target of water quality management or habitat conservation in the study area.

• ALGAE
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• v.27 no.3
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• pp.189-196
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• 2012

Twelve morphological characters and the biochemical composition of Undaria pinnatifida f. distans sporophytes growing on the rocky shores of Jindo and Wando and on cultivation ropes in Kijang were measured to determine whether each population could be characterized by morphological features and biochemical composition. The goal of this study was to compare phenotypic variations between populations as they relate to environmental conditions. The sporophytes of the Kijang population were two times longer and 19 times heavier than those at Jindo. Sporophylls of the Jindo U. pinnatifida population were significantly smaller in length, width, frill number, and weight than those at Wando and Kijang. Kijang Undaria plants showed the highest contents of total protein, crude fiber, total amino acids, the amount of essential amino acids, the proportion of total unsaturated fatty acids, and eicosapentaenoic acid. However, the Jindo population showed the greatest content of carbohydrates, lipids, and minerals (Zn and Ca) of the three U. pinnatifida populations. In particular, Zn content of Jindo plants was 30 times greater than that of Kijang plants. Thus, the proximate composition, mineral composition, amino acids, and fatty acids of Undaria pinnatifida plants were distinguishable among the three representative Undaria populations evaluated. These results suggest that morphological and biochemical differences of the three U. pinnatifida populations can be attributed to differences in environmental conditions of their habitats.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.395-401
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• 2008

Genetic diversity and differentiation within or among nine populations of introduced fish, largemouth bass Micropterus salmoides were assessed by AFLP. The AFLP analysis using three primer combinations generated 299.2. AFLP bands and percentage of polymorphic bands were similar in those nine populations, ranging 14.1 to 21%. Heterozygosity and genetic diversity within or among populations were quite low for all of these populations with average values ranging from 0.054 to 0.067 and from 0.069 to 0.085, respectively. Analyses of pairwise distance and genetic similarity among nine populations of Micropterus salmoides also revealed the similar results with low genetic differentiation one another. Although pairwise Fst values were low, they were indicated a clear distinct genetic differentiation among the nine populations. These results indicate that very small population of the largemouth bass was first introduced to Paldang reservoir and they are widely spread at most of aquatic habitats in Korea.

• Korean Journal of Ichthyology
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• v.22 no.3
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• pp.162-167
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• 2010

Ecological characteristics of Orthrias nudus from the Eoron Stream, Gangwon-do, Korea were investigated from January to December 2009. O. nudus inhabits mainly riffles of the upstream and mid-upstream stretches of Eoron Stream, which were composed of boulder and cobble bottoms. The current velocities in these habitats were 0.42~1.34 m/sec and depths were 15~46 cm. The sex ratio of female to male was 1 : 0.98. It is presumed that the spawning season is from April to June when water temperatures were $15{\sim}19.2^{\circ}C$. Sexually mature individuals appeared to be over one year of age. Frequency analysis of total length indicated that the group 58~99 mm in total length is represented by one-year-old individuals, and the group over 100 mm by two-year-old individuals. The average number of eggs in the ovaries was estimated as 4,119 per mature female. Stomach contents of O. nudus were composed of aquatic insects such as Ephemeroptera, Trichoptera and Diptera.