Lentic ecosystems, including lakes, reservoirs, and marshes, are vital ecological assets increasingly threatened by anthropogenic pressures, necessitating robust tools for assessing their biological integrity. This study aimed to develop and apply an aquatic plant-based Multi-metric Index (MMI) to evaluate the biological integrity of 90 lentic systems (primarily lakes and reservoirs) across the Republic of Korea, using a standardized dataset from a three-year national monitoring program (2022~2024). We selected eight metrics based on their ecological relevance, sensitivity to disturbance, and scientific robustness. These were organized into three categories: Species richness (30% weight), eutrophication and disturbance (30%), and habitat integrity (40%). Scoring criteria for each metric were established using cumulative distribution functions, and the final MMI scores were used to classify the ecosystems into five integrity classes (A: Excellent to E: Very Poor). The assessment revealed that the majority of the surveyed ecosystems (87.8%) were in a moderate to slightly poor state (Classes B, C, and D), with only 4.4% classified as excellent. Widespread loss of submerged and floating leaved aquatic plants suggests that many domestic lentic systems may be approaching or have already undergone a regime shift to a turbid, phytoplankton-dominated state. This MMI provides a scientifically-defensible tool for managing lentic ecosystems, underscoring the urgent need to restore aquatic plants communities by improving underwater light conditions and rehabilitating littoral habitats.

This study was conducted to develop a fish-based Multi-metric Index (MMI) for assessing the ecological health of lake ecosystems using fish assemblage data collected from the national lake biomonitoring program between 2022 and 2024. A total of 34 fish assessment metrics widely used in the United States, Europe, and Korea were first reviewed for applicability, from which 16 candidate metrics were selected. These candidate metrics were then evaluated in terms of statistical distribution characteristics, correlations with water quality variables, redundancy among metrics, and consistency with existing river-based metrics used in Korea. Based on these evaluations, eight core indicators and four supporting indicators were finalized. For ecological health scoring, boundary values for metric scoring classes were determined using percentiles (10-25-50-75-90%), and metric weights were applied to ensure balanced contribution and discriminative power among classes. The final set of metrics consisted of three indicators in the Diversity/Richness category, two in the Trophic category, two in the Tolerance category, and one in the Individual Health category, collectively reflecting the ecological responses of fish assemblages in lake environments. The developed MMI framework is expected to provide a robust and applicable tool for future ecological assessments and management of lakes in Korea.

This study presents a modified version of the Lake Benthic Macroinvertebrate Multimetric Index (LBMMI) originally proposed by Park et al. (2024) in Korea. Among the six core metric elements of LBMMI, two elements-total number of taxa and the proportion of predator taxa-were excluded, as they were considered to be strongly influenced by vascular hydrohytes following eutrophication. The revised LBMMI was constructed using the remaining four metrics: Pielou’s evenness index, proportion of insect taxa, individual proportion of oligochaetes and chironomids with blood tubules, and proportion of clinger taxa. Compared to the original LBMMI, the modified index showed approximately a 6% improvement in explanatory power for the first principal component (PC 1) in principal component analysis of environmental factors, and it also exhibited a broader range of discrimination. These results suggest that the modified LBMMI can be more effectively utilized for environmental assessment of lake ecosystems.

Zooplankton are dominant pelagic consumers in lake ecosystems with high population and biomass. Their broad geographical distribution, ease of quantification, and rapid responses to abiotic environmental factors, such as eutrophication, acidification, and climate change, make them highly suitable as indicator organisms for assessing lake ecosystem health. The multi-metric index (MMI) provides an effective framework for capturing the complex responses of biological communities to varying environmental stressors, making it a valuable approach for improving the practical effectiveness of lake ecosystem management based on biological assessments. This study introduces the Lake Zooplankton Assessment Index (LZAI), developed for 90 lakes in South Korea. The LZAI comprises four components: a sensitive species index based on cladocerans, a eutrophication index based on rotifers, a food web index based on copepods, and a habitat index based on species diversity. Applying the LZAI to 90 lakes showed that lake grades followed a normal distribution regardless of sampling season, though A-grade and E-grade lakes exhibited greater seasonal variability. When compared with the clustering results based on zooplankton community composition, the LZAI closely reflected the underlying patterns in community structure. However, in brackish lakes-where population densities are lower and Calanoida copepods dominate relative to freshwater lakes-the M1 and M4 indices were consistently low, while M2 and M3 were high. This suggests that the LZAI requires index adjustments tailored to regional and lake-type factors, including size, depth, and salinity. Incorporating biomass data into the index would further improve the accuracy of assessing community structure and its role in nutrient and energy cycling.

The absence of standardized, biology-based assessment criteria for lake ecosystems at the national level underscores the need for developing systematic and integrative phytoplankton-based evaluation tools. Phytoplankton are primary producers that regulate energy flow and nutrient cycling in lake ecosystems, and their rapid responses to environmental changes such as eutrophication, altered hydrodynamics, and seasonal fluctuations make them highly effective biological indicators. Multimetric indices (MMIs) offer a structured and integrative approach for capturing complex community level responses to environmental stressors, thereby enhancing the ecological relevance and management utility of biological assessment tools for lentic systems. This study presents the Lake Phytoplankton Assessment Index (LPAI), developed using long term ecological and water quality data from 90 lakes and reservoirs across South Korea. The LPAI comprises six ecologically meaningful metrics: total cell density (M2), cell density of flagellated algae (M10), cell density of harmful cyanobacteria (M17), cell density of eutrophic Chlorophyta (M18), relative abundance of saprophilous diatoms (M23), and relative abundance of eutraphentic diatoms (M25). Application of the LPAI demonstrated that lake health grades exhibited a broad and near-normal distribution across seasons, while summer assessments showed a marked increase in lower grade (C~E) lakes associated with elevated temperatures and cyanobacterial blooms. Conversely, winter assessments showed improved conditions due to reduced phytoplankton biomass and the dominance of low eutrophic diatom assemblages. Correlation analyses confirmed that the selected metrics captured distinct ecological gradients, particularly nutrient enrichment and organic matter driven turbidity, while PCA results indicated that the LPAI performed consistently across lake types without structural bias. Overall, the LPAI reliably reflects trophic conditions, harmful algal risks, and structural changes in phytoplankton communities, offering a scientifically grounded and management-relevant tool for evaluating the ecological health of Korean lakes and reservoirs.

This study investigates how lake morphology, water quality, and water-level fluctuations (WLF) collectively shape wetland plant communities across 90 lakes in the Republic of Korea. By analyzing morphological indices (Index of Basin Permanence; IBP, Rawson Index; RI), WLF, water quality, and vegetation data, we identified four distinct lake groups through cluster analysis. Group C, comprising large dams, was characterized by the highest IBP and extreme WLF. Despite having favorable water quality, this group exhibited the lowest species richness, suggesting that severe physical disturbance from WLF is a primary limiting factor for wetland plant community. In contrast, Group A (estuarine reservoirs) showed stable water levels but high nutrient concentrations, which led to eutrophic conditions and communities dominated by a few tolerant species. Group D, which included small agricultural reservoirs and floodplain wetlands, had complex shorelines (highest RI) and supported the higher diversity of aquatic plants. This indicates that habitat heterogeneity can mitigate moderate physical disturbances and enhance richness. Canonical Correspondence Analysis and Variation Partitioning Analysis revealed that community structure is primarily influenced by hydrological disturbance, chemical stress (eutrophication), salinity, and shoreline complexity. These analyses confirmed that the interplay of these environmental factors explains community variation more effectively than any single factor alone. Our findings demonstrate that lake plant communities are shaped by a complex interaction of geomorphological, hydrological, and chemical factors. Therefore, effective lake management must adopt an integrated approach, considering both water-level regulation and shoreline complexity to enhance ecological integrity.

Estuary is important in terms of biodiversity because it has the characteristics of transition waters, created by the mixing of fresh- and seawater. The estuarine water circulation provides a variety of habitats with different environments by inducing gradients in the chemical and physical environment, such as water quality and river bed structure, which are ultimately the main factors influencing biological community composition. If the water circulation is interrupted, the loss of brackish areas and the interception of migration of biological communities will lead to changes in the spatial distribution of biodiversity. In this study, among the sites covered by the Estuary Aquatic Ecosystem Health Assessment, we selected study sites where changes in biodiversity can be assessed by spatial gradient from the upper reaches of the river to the lower estuarine area. The α-, γ- and β-diversity of diatom, benthic macroinvertebrates, and fish communities were calculated, and they were divided into open and closed estuary data and compared to determine the trends in biodiversity variation due to estuarine circulation. As results, all communities showed higher γ-diversity at open estuary sites. The benthic macroinvertebrate community showed a clear difference between open and closed estuaries in β-diversity, consequently the estuarine transects were considered as a factor that decreases spatial heterogeneity of their diversity among sites. The biodiversity trends analyzed in this study will be used to identify estuaries with low γ- and β-diversity by community, providing a useful resource for further mornitoring and management to maintain estuarine health.

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries (78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

This study was identified the distribution of vegetation in domestic estuaries and analysed the relationship with environmental fcators based on the health assessment data of the estuary ecosystem surveyed between 2016 and 2018. Of the 325 estuaries surveyed, 187 vegetation communites were investigated in 300 estuaries and 53 halophyte communites accounted for 28.3%. No vegetation distribution was found in the other 25 estuaries. Considering the circulation of estuary, 41 halophyte communites were investigated in open estuaries and 26 halophyte communites in closed estuaries. As a result of canonical correlation analysis (CCA) between the entire distributed vegetation community and environmental factors, salinity (conductivity), T-N, and T-P concentrations were strongly correlated. Among the riverbed material materials of the estuary, the composition ratio of silt, sand, and pebble was the most correlated. Therefor, it is estimated that the distribution location of the halophyte communites were differentiated by being influenced by the sea ares, estuary circulation type, resistance to salinity and riverbed material ratio.

This study analyzed the relationship between the community structure of benthic macroinvertebrates and habitat changes in open estuaries among the sites included in the national estuary monitoring program. The estuary survey was conducted under the “Guidelines for Investigation and Evaluation of Biometric Networks” and classified by sea area, 80 places in the East Sea, 102 places in the South Sea, and 19 places in the West Sea were investigated. In a total of 201 open estuaries, benthic macroinvertebrates were identified with 4 phyla, 9 classes, 41 orders, 139 families, 269 species and 196 species in the East Sea, 182 species in the South Sea, and 90 species in the West Sea. The highest population densities were Insecta in the East Sea, the Malacostraca in the South Sea, and the Annelida in the West Sea. Through SIMPER analysis, species contributing to the similarity of benthic macroinvertebrates communities in each sea area were identified. Some species greatly influenced the similarity of clusters. The benthic community in the East Sea was affected by the salinity, so the contribution rate of freshwater species was high. On the other hand, the benthic communities of the South and West Seas showed species compositions are influenced by the substrate composition. As results, the benthic macroinvertebrate community in Korean estuaries was impacted by salinity and substrate simultaneously, and the close relationship with geographical distance was not observed. The result of this study is expected to be used to respond to environmental changes by identifying and predicting changes in the diversity and distribution of benthic macroinvertebrates in Korea estuaries.

An estuary is an area where a freshwater river or stream meets the ocean. Even before the importance of the value of estuaries was recognized, the estuary was lost because of large-scale conversion by draining, filling, damming, and dredging. In South Korea, 643 estuaries are located, and the total area is 3,248,300 ha, accounting for 32.5% of the total area of South Korea. Over 35% of Korean estuaries are closed estuaries which are only temporally connected with the sea, either permanently or periodically. Since 2008, in order to preserve the estuary ecosystem and solve major issues in the estuary by accumulating knowledge about the estuarine ecosystem, the Ministry of Environment of Republic of Korea has been conducting the “Estuarine Ecosystem Monitoring and Assessment Project”. At 668 sites of 325 estuaries, epilithic diatom, benthic macroinvertebrate, fish, and vegetation are investigated, and the habitat condition of each site is evaluated using the newly developed biotic index. More than 100 researchers annually record 2,097 species of estuaries according to the standardized survey guidelines over the past 14 years and provide strictly managed data necessary for establishing estuaries conservation policies. As a result of bibliometric analysis of 1,195 research articles related to the monitoring and assessment of the estuarine ecosystem, research on pollutants such as heavy metals and sediment control have recently been conducted. “Estuarine Ecosystem Monitoring and Assessment Project” is an ecological monitoring type of long-term mandated monitoring that is usually focused on identifying trends. Although it is difficult to identify the mechanism influencing a change in an ecosystem through long-term mandated monitoring, providing empirical data for supporting evidence-based policy, decision-making, and the management of ecosystems. In order to increase the efficiency of the project, research to investigate the relationship between sediments and pollutants and organisms can be conducted at specific estuaries or sites to compensate for the shortcomings of mandatory monitoring.

본 연구는 2008년부터 2016년까지 한강 지류 중랑천을 대상으로 수환경 변화에 따른 어류 군집 양상을 파악하고자 실시하였다. 조사결과, 중랑천에서 서식하는 어류는 총 9과 37종 8,421개체로 나타났으며 과별 출현 종수는 잉어과에서 23종 (62.2%)으로 가장 많은 종이 출현하였고, 생태계교란종 및 외래종은 모두 강우기 후 출현하는 특성을 보였다. 수질변화에 따르면, BOD, EC, TN, TP의 변화는 강우량의 증가에 따라 감소하는 양상을 보이는 반면, SS 변화는 증가하는 양상을 보였다. 지점간 CA결과 한강 본류와 인접한 St. 7과 St. 1, 3, 5가 어류의 출현양상 차이를 보였으며, PCA 분석결과 상류에서 하류, 강우기 전과 후의 어류 출현양상과 유기오염지표의 변화 양상을 보였다.

본 연구는 하천 내 하도 자연성이 어류 건강성에 미치는 영향을 알아보기 위하여, 2008~2016년 간 한강권역의 자연사행하천과 하도정비로 직강화된 하천의 수질환경요인과 FAI를 비교 분석하였다. 하도 자연성에 따른 우점종의 출현빈도를 분석한 결과, 자연사행하천에서 민감성 및 충식성 어종이 우세한 반면, 하도 직강화 하천에서는 내성 및 잡식성 어종이 우점하는 빈도가 높은 양상을 보였다. 하도 및 저수로의 직강화로 인해 하도 자연성이 감소함에 따라 FAI가 감소하는 경향을 보였으며, 특히 생태적 어류군집구조 특성이 반영된 메트릭인 민감종수 (M3) 및 충식종의 개체수 비율 (M6)의 감소와 잡식종의 개체수 비율 (M5)의 증가가 FAI 변화에 주요요인으로 나타났다. 하도 자연성 감소에 따른 연도별 FAI 하락은 BOD, TN, TP, 전기전도도, 탁도의 증가와 높은 상관관계를 보여, 하도 및 저수로의 직강화로 인한 수질변화는 물리적 서식환경의 교란과 함께 어류 건강성에 주요 영향요인으로 판단된다.

With increasing public awareness regarding radon, this study has been conducted with the aim of providing more accurate information about radon to the public. We investigated the radon emissions from gypsum boards, which are known to emit relatively higher levels of radon among the building materials available on the market. Radon emissions were measured over three weeks using the closed chamber method with nuclear track detectors. For ceiling materials, the arithmetic mean of the radon emissions was 43.8 ± 42.2 Bq/m3 (geometric mean: 28.9 ± 5.6), 156.2 ± 150.5 mBq/m2/h per unit area (geometric mean, 103.1 ± 2.7) and 21.1 ± 19.9 mBq/kg/h per unit mass (geometric mean: 14.4 ± 2.6). Regarding the wall materials, the arithmetic mean of radon emissions was 24.1 ± 24.0 Bq/m3 (geometric mean: 15.6 ± 2.6), 133.3 ± 143.4 mBq/m2/h per unit area (geometric mean, 76.8 ± 3.0) and 13.0 ± 10.4 mBq/kg/h per unit mass (geometric mean, 9.5 ± 2.3). According to the results of this study, higher radon concentrations and emissions were detected in the ceiling materials than in the wall materials, but these values were lower than those previously measured in building materials.