• Animal Systematics, Evolution and Diversity
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• v.33 no.1
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• pp.37-44
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• 2017

The present census on freshwater bryozoans in the Han River, Geum River and in lentic water bodies in Gangwon Province revealed three gymnolaemate species. Two of them-Hislopia prolixa Hirose and Mawatari, 2011 and Victorella pavida Saville Kent, 1870 were recorded for the first time from South Korea. Paludicella articulata (Ehrenberg, 1831), on the other hand, had already been documented from a few sites since 1941. The bryozoans, all belonging to the order of Ctenostomata, were found on a variety of substrates in freshwater (H. prolixa and P. articulata) and brackish habitats (V. pavida). Hislopia prolixa had recently been established as a new species and this is the first record for an occurrence outside of Japan, where it had been newly described from Lake Biwa and nearby satellite lakes.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.141-152
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• 2001

Abundance of autotrophic picoplankton (APP) and their contribution to phytoplankton biomass were assessed in seven brackish lagoons and five freshwater reservoirs in the summer season. Phycocyanin-rich picocyanobacteria dominated APP in lagoons, while phycoerythrin-rich picocyanobacteria dominated APP in freshwater reservoirs. The cell density of APP ranged from $3.6{\times}10^3$ to $5.0{\times}10^6\;cells/ml$ (median $2.5{\times}10^5$) in brackish lagoons and from $3.8{\times}10^4$ to $3.6{\times}10^5\;cells/ml$ (mdian $1.3{\times}10^5$) in reservoirs. Carbon biomass ranged from 1.0 to $1,385.0\;{\mu}gC/L$ in lagoons and from 15.3 to $128.2\;{\mu}gC/L$ in reservoirs. APP cell density in Lake Kyungpo was over $10^6\;cells/ml$in all three surveys, which is one of the highest values recorded in all over the world. During the thermal stratification in Lake Soyang, the maximum abundance of APP and their maximum contribution to phytoplankton biomass were observed near the thermocline. This study showed that APP sometimes can contribute significantly to phytoplankton biomass both in lagoons and reservoirs with the range from 0.1 to 85.0%. APP which have been overlooked in the past studies appears to be important primary producers in Korean lake ecosystem.

• Journal of Marine Bioscience and Biotechnology
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• v.3 no.1
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• pp.13-17
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• 2008

The Congo has a maritime coastline of 40 km, covering an area of $2,345,409km^2$. The fluvial system covers around $34,000km^2$ in a network of more than 33,000 km of rivers, principal tributaries, and streams. There are around 1,000 known species of fish, essentially freshwater and some brackish. The lakes of the Rift Valley contain the richest lacustrine fauna in the world. The family of Cichlidae alone has more than 900 species. At the same time, the lakes are profoundly different. Lake Tanganyika has 250 species of fish, of which 216 are endemic, whereas Lake Kivu contains only 32 and 16, respectively. A dense hydrographic network of water surfaces, inundated plains and lakes cover around $86,080km^2$ (3.5% of the national area) and have a considerable aquatic potential. The large peripheral lakes of the East cover around $48,000km^2$ of which 47% are under Congolese jurisdiction. The respective areas belonging to the Congo are: Lake Tanganyika, $14,800km^2$; Lake Albert, $2,420km^2$; Lake Kivu, $1,700km^2$; Lake Edward, $1,630km^2$; Lake Mo$\ddot{e}$ro, $1,950km^2$. Another two important lakes in the interior, Lake Tumba and Lake Mai-Ndombe, cover (between them) 2,300 and $7,000km^2$, depending on season (less in the dry season and more in the rainy season). There are also the lakes of the Kamalondo depression ($6,256km^2$), Lake Tshangalele ($446km^2$) and Lake N'Zilo ($280km^2$).

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.499-506
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• 2013

To estimate the effect of algae to particulate organic matter in the upper regions of brackish Lake Sihwa, temporal and spatial variations of particulate organic carbon (POC) and phytoplankton pigments (chlorophyll a; Chl-a, pheophytin-a; Pheo-a), and their relationships were studied at seven sites of the brackish regions from March to October 2005 and 2006. POC concentration varied from 1.0 to $76.6mgL^{-1}$ (mean $7.4mgL^{-1}$), with maximal concentrations occurring in the middle parts of the study area in spring of 2005 and 2006. Concentrations of Chl-a and Pheo-a varied from 1.3 to $942.9{\mu}gL^{-1}$ (mean $71.0{\mu}gL^{-1}$) and $1.4{\sim}1,545.5{\mu}gL^{-1}$ (mean $59.9{\mu}gL^{-1}$), respectively, and corresponded closely with variation in POC. During the study period Pheo-a concentration was 44.2% of total Chl-a, implying that non-living or inactive phytoplankton is also the important part of phytoplankton-derived POC in brackish regions of Lake Sihwa. From the positive linear relationships between POC and phytoplankton pigments (POC with Chl-a (r=0.93), total Chl-a (r=0.88), and Pheo-a (r=0.81)), it is suggested that phytoplankton was a significant component of POC in the upper regions of brackish Lake Sihwa. On the other hand, the ratios of POC/Chl-a and POC/total Chl-a (Chl-a+Pheo-a) were 82.9 and 35.9, respectively. The ratio of POC/total Chl-a is similar to those reported in previous studies, including 40~60 in estuaries. This study suggests that Pheo-a concentration is considered in estimation of POC concentration from phytoplankton pigments in aquatic systems with high content of Pheo-a, like an upper region of blackish Lake Sihwa.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.206-215
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• 2008

Temporal and spatial distributions of salinity, temperature, dissolved oxygen (DO), and turbidity were investigated at seven sites in the upper regions of brackish Lake Sihwa with a limited water exchange, from March to October 2005. During the study period, salinity and temperature varied $0.1{\sim}29.9\;psu$ and $4.7{\sim}28.1^{\circ}C$, respectively, depending on seasons and sites sampled. A distinct halocline profile showing the maximum density gradient (difference over $20\;psu\;m^{-1}$ between surface and bottom layers) was observed during the rainy season, due to the decrease of salinity in surface layers by freshwater inflow. This result implies that rainfall event is the important factor forming the halocline. On the other hand, the depth and location of haloeline varied with the amount of seawater through the sluice gates and the operation systems (inflow or outflow). High DO (over 300% saturation) was observed at surface layer above the halocline in April when red tide occurred, whereas low DO (below 20% saturation) was at the bottom layer below the halocline in the rainy season. Turbidity ranged $1.5{\sim}80.3\;NTU$ showing the maximum turbidity at the layers above or upper the halocline. As a result, the distributions of DO and turbidity in the upper regions of brackish Lake Sihwa were largely affected by the variation of salinity. Also, when the halocline was formed, the water quality between upper and lower water layers may be expected completely different. This study suggests that the physicochemical characteristics of water in the brackish regions are closely associated with the causes of eutrophication such as red tide and DO deficit.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.336-341
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• 2000

This study was conducted to clarify the habitat characteristics and distribution of seagrass. Zostera marina L. (Zosteraceae) in the brackish Hwajinpo Lake, Korea in June 1998 and July 2000. Z. marina beds were distributed along the sea-side cost of the lower lake mouth at 0.8 to 1.5m in death, and the seagrass bed area was about 3,200 m$^{2}$. Salinity, water temperature and pH were in the range of 8.0${\sim}$23.0$%_{o}$, 22.0${\sim}$23.7$^{\circ}C$ and 8.34${\sim}$8.62, respectively. Nutrient concentrations were generally now (TN: 24.34 ${\mu}$M, NH$_{4}$-N: 2.57 ${\mu}$M, NO$_{3}$-N: 0.56 ${\mu}$M, NO$_{2}$-N: 0.27 ${\mu}$M, TP: 2.08 ${\mu}$M, PO$_{4}$-P: 0.34 ${\mu}$M). Suspended particulate matters (SPM) concentration averaged 62.8 mg/l and particulate organic matter (POM) averaged 21.3 mg/l. Organic content of SPM averaged 33.9%. The beds substratum was composed of well-sorted, fine sand and its mean brain size was 3.13${\Phi}$. The Z. marina vegetation was almost submerged, and the morphological characteristics can be classified as steno-leaf phenotype by the shoot length, leaf width, and number of leaf vein. Shoot length and leaf width were 70.0${\sim}$126.5 cm and 5${\sim}$7 mm, respectively. Shoot densities ranged from 264 to 296/m$^{2}$, and the plants biomass was estimated at 332.6 to 373.0 g dw/m$^{2}$. Therefore, the habitats of Z. marina in Korea were recognized in a brackish lake, and morphological characteristics appeared to be variable.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.3
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• pp.172-183
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• 2005

To assess the macrobenthic community of oligohaline Youngam Lake, which is located at the Youngsan Watershed on the southwest part of Korea, macrobenthic fauna were collected at 45 stations during May, 2002. A total of 16 species of macrofauna were recorded with a mean density of 240 individuals per $m^2$ and a mean biomass of 7.07 g wet weight per $m^2$. Major dominant faunal groups were crustacean arthropods in terms of the number of species and abundance, and polychaete annelids in terms of biomass. The mean grain size was $5.7\;{\phi}$ which was dominated by silt fraction. The hydrological environment of the lake was characterised as an oligohaline environment with a mean surface water temperature of $17.8^{\circ}C$ and a mean salinity of 2.08 psu. The major dominant species were amphipods, Corophium sp. ($31\%$) and Jesogammarus sp. ($25\%$). Lowe. values of species diversity (H') with a mean of 0.81 (less than 1.0 from most stations) reflected the overall poor faunal diversity in this area. Multivariate analysis suggested that this benthic faunal community could be divided into four sub-regions such as the area from lake proper to water channel to the south, the stations located at the entrance and northern water channel, the stations near the dike, and the lake proper area. Freshwater and brackish water species which occurred in each station group were corresponded to the oligohaline salinity regime. Bottom hypoxia appeared in the entrance part of the lake between dyke and lake proper on May, which was resulted from stratification from spring season. These facts imply that marine macrobenthos were severely impacted by low salinity and a consequent hypoxia after embankment of the lake due to the restriction of water circulation.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.313-314
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• 2001

The palaemonid shrimp Exopazaemon modestus inhabits the freshwater of the Indo-West Pacific, Siberia, Manchuira, Korea, China, Taiwan (Holthuis, 1980) and is abundant in the fresh water areas of southwest of Korea. Palaemonid shrimps are adapted to a variety of habitats in freshwater, brackish and marine environments. They play important role in the ecosystem of fresh, brackish and marine waters, acting as predators feeding on algae, detritus, crustaceans and meiofauna (Bell and Coull, 1978) and in turn, as preys for fishes and other predators (Anderson, 1985). (omitted)

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.2
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• pp.130-139
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• 2004

Shiwha Lake is an excellent example of a body of water restored from a state of heavy pollution to a cleaner and more ecological state. This paper will explore techniques and methods available to landscape planning for the creation of new migratory birds habitats in Shiwha Lake. Because Shiwha lake is located adjacent to a new industrial site on reclaimed land, any planning effort aimed at restoring bird habitats must carefully consider the existing context. This plan had 3 goals; (1) to restore the coastal environment, (2) to create a habitat for migratory birds, and (3) to administer environmental education programs. To achieve these goals, several objectives were determined and planning criteria were proposed for topology, water environment(fresh, brackish and salt water swamps), zoning(for experts and general visitors), circulations, planting and mounding. The flora and fauna of the site was surveyed, and 5 alternatives were suggested and compared in several aspects. Planting species were carefully selected considering target birds and habitat requirements. In order to increase bio-diversity of the site, the plan proposed multi-staired mounds and extensive drainage systems. Bird watching facilities with natural materials, and the remote observing system using CCTV and the internet were some of the ecological techniques recommended by the plan. The bird watching trails are divided into two different zones for experts and general visitors.

• Ocean Science Journal
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• v.42 no.4
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• pp.223-230
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• 2007

To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen $(C_{org}/N_{org})$ (mean = 24) were much higher than ratios of organic carbon to total nitrogen $(C_{org}/N_{tot})$ (mean= 12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes. Stable isotope ratios for organic nitrogen were, on average, $5.2\%_{\circ}$ heavier than ratios of inorganic nitrogen in Lake Shihwa, but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on average, $1.4\%_{\circ}$ heavier than those for residual organic carbon, reflecting the preferential oxidation of $^{13}C$-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments. This also suggests that the ratio of $(C_{org}/N_{org})$ and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter.