• Journal of Korean Society on Water Environment
• /
• v.25 no.6
• /
• pp.951-963
• /
• 2009

The community structure and ecological characteristics of fish community in Lake Paldang were investigated from May to September 2008. During the survey period, 53 species belonging to 13 families were collected. Dominant species was Squalidus japonicus coreanus representing 81.8% of total number and 25.7% of total biomass of collected fish and subdominant species was Lepomis macrochirus representing 3.3% of total number and 18.9% of total biomass of collected fish. There were 20 Korean endemic species (38% of collected species number) including Cottus koreanus and 4 exotic species (7.5%) including Micropterus salmoides. The similarity analysis of fish communities among water areas of Lake Paldang using UPGMA showed that fish community of North-Han River was similar to that of South-Han River area and was different from that of Gyeongan River area. Long-term variation of fish community from 1972 to present study in Lake Paldang showed decrease of the species numbers after dam construction until 1994, and gradual increase from 1996 to present study indicating the disturbance of lentic system by dam construction in the 1980s. The increase of species number in the late 2000s may results in part from the increase of survey sites of successive studies. L. macrochirus which was designated as a domestic ecosystem-disturbing alien species with wide food niche have shown more than 20% of relative abundance since 1996 indicating the adverse effect on not only fish community but also aquatic ecosystem food web of Lake Paldang.

• Journal of Ecology and Environment
• /
• v.38 no.2
• /
• pp.133-143
• /
• 2015

Freshwater macrophytes improve the structural heterogeneity of microhabitats in water, often providing an important habitat for zooplankton. Some studies have focused on the overall influence of macrophytes on zooplankton, but the effects of macrophyte in relation to different habitat characteristics of zooplankton (e.g., epiphytic and pelagic) have not been intensively studied. We hypothesized that different habitat structures (i.e., macrophyte habitat) would strongly affect zooplankton distribution. We investigated zooplankton density and diversity, macrophyte characteristics (dry weight and species number), and environmental parameters in 40 shallow wetlands in South Korea. Patterns in the data were analyzed using a self-organizing map (SOM), which extracts information through competitive and adaptive properties. A total of 20 variables (11 environmental parameters and 9 zooplankton groups) were patterned onto the SOM. Based on a U-matrix, 3 clusters were identified from the model. Zooplankton assemblages were positively related to macrophyte characteristics (i.e., dry weight and species number). In particular, epiphytic species (i.e., epiphytic rotifers and cladocerans) exhibited a clear relationship with macrophyte characteristics, while large biomass and greater numbers of macrophyte species supported high zooplankton assemblages. Consequently, habitat heterogeneity in the macrophyte bed was recognized as an important factor to determine zooplankton distribution, particularly in epiphytic species. The results indicate that macrophytes are critical for heterogeneity in lentic freshwater ecosystems, and the inclusion of diverse plant species in wetland construction or restoration schemes is expected to generate ecologically healthy food webs.

• Korean Journal of Environment and Ecology
• /
• v.32 no.3
• /
• pp.274-288
• /
• 2018

This study investigated the environmental factors and fish assemblage in 42 wetlands between spring and autumn of 2017 to evaluate the fish distribution and deduce the management strategy for improving biodiversity in created wetlands located at the Nakdong River basin. The investigation identified a total of 30 fish species and found that the most of wetlands were dominated by exotic fishes such as Micropterus salmoides and Lepomis macrochirus. Fish species such as Rhinogobius brunneus, Opsariichthys uncirostris amurensis, Zacco platypus were less abundant in the area with high density of Micropterus salmoides (static area) because they preferred the environment with active water flow. The pattern analysis of fish distribution in each wetland using the self-organizing map (SOM) showed a total of 24 variables (14 fish species and 10 environmental variables). The comparison of variables indicated that the distribution of fish species varied according to water depth and plant cover rate and was less affected by water temperature, pH, and dissolved oxygen. The plant cover rate was strongly associated with high fish density and species diversity. However, wetlands with low plant biomass had diversity and density of fish species. The results showed that the microhabitat structure, created by macrophytes, was an important factor in determining the diversity and abundance of fish communities because the different species compositions of macrophytes supported diverse fish species in these habitats. Based on the results of this study, we conclude that macrophytes are the key components of lentic freshwater ecosystem heterogeneity, and the inclusion of diverse plant species in wetland construction or restoration schemes will result in ecologically healthy food webs.

• Korean Journal of Ecology and Environment
• /
• v.56 no.4
• /
• pp.375-383
• /
• 2023

To determine the cause of the population decline in Gobiobotia naktongensis, substrate preference and burying behaviour were investigated in this study. In general, the species was shown to prefer a substrate size of 1 mm or less, depending on the flow. In addition, the burying depth varied according to the size of the fish and increased with a decrease in water temperature. Our findings showed that the main cause of the population reduction was the physical changes in the substrate structure due to the dams or barrages construction. Notably, the accumulation of silt and mud in the substrate upon the formation of an upstream lentic water region for structural construction and bed armouring caused by scouring and reduced downstream inflow of fine sediment were deterministic in the fish habitat changes, causing problems in burying. As sand substrate structure is critical for the survival and inhabitation of psammophilous species, efficient strategies should be developed with proper habitat management to reduce the anthropogenic damage

• Ecology and Resilient Infrastructure
• /
• v.10 no.4
• /
• pp.171-183
• /
• 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 Ecology and Environment
• /
• v.42 no.4
• /
• pp.476-486
• /
• 2009

Major objective of our study was to introduce initial researches of national long-term ecological monitoring studies on Daechung Reservoir, as one of the representative lentic reservoir ecosystems in Korea. For the long-term ecological research (LTER), we conducted preliminary field monitoring during 2008~2009 and analyzed biological parameters such as phytoplankton, zooplankton, and freshwater fish along with chemical water quality and empirical model analysis. According to phytoplankton surveys, major taxa have varied largely depending on seasons and sites sampled. Overall phytoplankton data showed that cyanophyta dominated in the summer period and diatoms dominated in the winter. In zooplankton analysis, 25 species including 20 rotifers, 3 cladocerans and 2 copepods were collected during the survey. The relative abundance of rotifers (86.5%) was always greater than that of cladocerans (6.3%) or copepods (5.1%). There were distinct spatial and inter-annual changes in the abundance of zooplankton in the reservoir, displaying similar patterns in three sites with the exception of S3 during the study. According to fish surveys, 8 families and 39 species were observed during 2008~2009. The most dominant fish was an exotic species of Lepomis macrochirus (23%), indicating an severe influence of exotic species to the ecosystem. TP averaged $17.9\;{\mu}g\;L^{-1}$ ($6{\sim}80\;{\mu}g\;L^{-1}$), which was judged as a mesotrophy, and showed a distinct longitudinal gradients. TN averaged $1.585\;{\mu}g\;L^{-1}$ during the study and judged as hypereutrophic condition. Unlike TP, TN didn't show any large seasonal and spatial variations. Under the circumstances, nitrogen limitation may not happen in this system, indicating that nitrogen control is not effective in the watershed managements. These data generated in the LTER station will provide key information on long-term biological and water quality changes in relation to global warming and some clues for efficient reservoir ecosystem managements.

• Journal of Environmental Impact Assessment
• /
• v.31 no.6
• /
• pp.409-422
• /
• 2022

Riverine wetlands are an important element of the river ecosystem and account for approximately 38% of the inland wetlands surveyed so far. The Shincheon Wetland located in Mangyeong River is also a channel wetland as the flow rate is slowed by the constructed weirs, leading to sediment accumulation. To identify the conservation value and ecological characteristics of Shincheon Wetland, its vegetation and plant diversity were identified using a phytosociological method, and a total of 45 vegetation-related datasets were collected. Overall, 24 plant communities, comprising a total of 153 taxa (49 families, 117 genera, 146 species, 2 subspecies, 5 varieties) were identified. The plant with the highest appearance rate in the communities was Humulus japonicus Siebold & Zucc. In addition, annual herb species, including Rumex crispus L., Bromusjaponicus Thunb., Erigeron annuus (L.) Pers., and Artemisia indica Willd. were frequently observed to be growing in the secondary grassland. Naturalized plants were surveyed in the 38 taxa; the urbanization index was 10.3% and the naturalized index was 24.8%. Plant communities were largely classified into submerged vegetation, floating and floating-leaved vegetation, annual and biennial vegetation, perennial herb vegetation, and woody vegetation. The distribution of plant communities reflecting various habitats, including the lentic and lotic zone maintaining a constant water depth, littoral zone experiencing intermittent water level fluctuations, and dry floodplain environment was also confirmed. Overall, plant community development plays an important role in the habitat for wild animals; therefore, it is expected to positively impact biodiversity enhancement.

• Ecology and Resilient Infrastructure
• /
• v.9 no.4
• /
• pp.237-246
• /
• 2022

Owing to their high bioproductivity and unique physical environment, estuarine wetlands are gaining importance in national biodiversity management and habitat conservation. With regard to conservation and management of estuarine wetlands, this study analyzed the ecological characteristics of Gahwacheon Estuarine Wetland, an open estuary with various habitat types. Data from vegetation and biotic surveys have shown that 12 plant communities of five physiognomic vegetation types, including lentic herbaceous vegetation, halophytic herbaceous vegetation, and chasmophytic herbaceous vegetation. Due to the discharge of Namgang Dam and the effect of the tide, vegetation are distributed along the narrow waterside area. In terms of biodiversity, a total of 715 species, including 12 endangered wildlife species, were identified. Species diversity was relatively high in sections I and III where various riverbed structures and microhabitats were distributed. Due to the effect of the brackish water area following the inflow of seawater, endangered wildlife of various functional groups were also found to be distributed, indicating the high conservation value of that area. The collection of ecological information of the Gahwacheon 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 Environmental Biology
• /
• v.41 no.2
• /
• pp.101-108
• /
• 2023

Recently, in relation to climate change, many studies have been conducted to predict the potential habitat area and distribution range of tilapia and the suitability of habitat for each species. Most tilapia are tropical fish that cannot survive at water temperatures below 10 to 12℃, although some tilapia can survive at 6 to 8℃. This study predicted habitable areas and the possibility of spreading of habitat ranges of tilapia (Oreochromis niloticus and Oreochromis aureus) known to inhabit domestic streams. Due to climate change, it was found that habitats in the Geum River, Mangyeong River, Dongjin River, Seomjin River, Taehwa River, Hyeongsan River, and the flowing in East Sea were possible by 2050. In addition, it was confirmed that tilapia could inhabit the preferred lentic ecosystem such as Tamjin Lake, Naju Lake, Juam Lake, Sangsa Lake, Jinyang Lake, Junam Reservoir, and Hoedong Reservoir. In particular, in the case of tilapia, which lives in tributaries of the Geumho River, Dalseo Stream, and the Nakdong River, its range of habitat is expected to expand to the middle and lower of the Nakdong River system. Therefore, it is judged that it is necessary to prepare physical and institutional management measures to prevent the spread of the local population where tilapia currently inhabits and to prevent introduction to new habitats.

• Korean Journal of Ecology and Environment
• /
• v.55 no.3
• /
• pp.201-211
• /
• 2022

The macroinvertebrate community in the Singal reservoir, Yedang and Juam lake was investigated three times from April 2021 to October 2021. Each lake was investigated by dividing it into inflow, middle-flow, and outflow. Additionally, sampling was conducted again by dividing it into the edge and center parts at each inflow, middle-flow, and outflow. Eight families of benthic macroinvertebrates were collected except for chironomids in the sampling sites. Dominant macroinvertebrates were investigated as chironomids, and Tubificidae was sub-dominant organisms. The density of macroinvertebrate community was higher in the edge area than in the center bottom of the lakes. The density of chironomids was low when the water level was high but was high when the water level was low. In the edge area of the middle-flow in Singal reservoir, the density of chironomids was 1,208 ind. m^-2 in April when the water level was high, but it increased to 1,401 ind. m^-2 in July when the water level was low. Similarly, the density of chironomids at the outflow of Yedang lake was high (1,990 ind. m^-2) in July when the water level was low. The density of chironomids also decreased along with the increasing water level at all edge areas of Juam lake. These results indicated that it will be necessary to consider the water level when studying macroinvertebrate communities in the lake.