UV and O3 are materials used in the water treatment process, and many studies have been reported to remove organic matters, contaminants, and microorganisms. In this study, we were investigated effects of Chirnomidae (Chironomus flaviplumus, Chironomus riparius), which are contamination indicator species to exposure UV and O3 for the survival rate, body color change and gene expression response. The survival rate of C. flaviplumus exposed to UV decreased to about 70% after 24 hours, and C. riparius about 50%. There was no change in the survival rate of C. flaviplumus exposed to O3, and C. riparius decreased to 95% after 10 minutes of exposure, but there was no change during the subsequent exposure time. In addition, UV and O3 exposure to the two species in body color faded in a time-dependent. In the HSP70 gene expression, C. riparius showed an increase in expression after UV exposure compared to the control group, and a significant difference was shown 12 hours after exposure (P<0.05). C. flaviplumus exposed to O3 showed a relatively low expression compared to the control group, and showed a significant difference at 10 minutes and 1 hour after exposure (P<0.05). These results reported the ecotoxicological effects on Chironomidae according to UV and O3 exposure. Therefore, the results of this study can be used as basic data to understand the effects of UV and O3, which are disinfectants used in water treatment plants, on Chirnomidae entering plants. Key words: Chironomus flaviplumus, Chironomus riparius, UV, O3, acute toxicity, survival

Cadmium (Cd), a heavy metal found in the aquatic environment, accumulates in organisms through the food chain. In the study, we investigated the survival rates, measurement of body Cd levels, and expression analysis of the stress response genes (Heat shock protein 70: HSP70 and Heat shock protein 60: HSP60) and antioxidant enzyme Glutathione S-Transferases (GST) on benthic oligochaete worm Tubifex tubifex exposed three concentrations of Cd, to analyze the bioaccumulation and changes of stress gene expressions to exposure toxicity of the Cd-spiked sediment. Survival rates of T. tubifex exposed to the Cdspiked sediment were 93% at 0.4 mg kg-1 Cd, 96% at 1.87 mg kg-1 Cd, and 93% at 6.09 mg kg-1 Cd for 10 days. Cd concentration in the body of T. tubifex was higher than that in the sediment. After Cd exposures for 10 days, the body Cd levels were 18.4 mg kg-1, 13.06 mg kg-1, and 79.11 mg kg-1 at exposed three concentrations of Cd, respectively. Upregulation of HSP70 gene expression was observed at all concentrations of exposed Cd as a time-dependent manner, whereas transcriptional expression of the HSP60 gene increased as a timedependent manner in T. tubifex exposed to the relative high concentration (6.09 mg kg-1) of Cd. However, GST gene expression increased on day 1 at all concentrations after Cd exposures, and then downregulated until 10 days. These results indicate to ecotoxicological and molecular effects in benthic oligochaete worm T. tubifex to Cd-spiked sediment and provide the basic information for the utilization of environmental toxicity assessment using the T. tubifex as a aquatic pollution indicator species.

The Hangang River* is necessary to manage the water environment of severe pollution due to the high density of residential areas, parks, and agriculture and the large population concentrated there. Benthic macroinvertebrates, such as chironomids larvae, are bioindicator species that reflect environmental changes and are crucial for water quality monitoring. In this study, we investigated morphological characteristics and molecular analysis of the chironomids larvae inhabiting the Hangang River area for water environment surveys. For this research, 20 rivers, lakes, and urban area in the Hangang River basin were selected. Chironomids larvae were collected from July to September 2022, and their appearance and characteristics were identified through morphological identification. In addition, phylogenetic analysis was performed based on the mtCOI gene sequences of the collected chironomids larvae, and identification at the genus level was confirmed. As a result, 32 species and 18 genera of 3 subfamilies of Chironomidae larvae were identified, and Stictochironomus sp. dominated most sites (6 sites). The morphological characteristics of the identified chironomids larvae, such as the mentum, ventromental plate, and antenna, were organized into table and pictorial keys, and a Bayesian inference molecular phylogeny was presented. These results provide basic morphological information for genus-level identification and can be used as fundamental information for water quality management. *The public nomenclature following by NGII 2015

Recently, Korean government has introduced Multi Metric Indices (MMI) using various biocommunity information for aquatic ecosystem monitoring and ecosystem health assessment at the national level. MMI is a key tool in national ecosystem health assessment programs. The MMI consists of indices that respond to different target environmental factors, including environmental disturbance (e.g. nutrients, hydrological and hydraulic situation of site etc.). We used zooplankton community information collected from Korean lakes to estimate the availability of candidate zooplankton MMI indices that can be used to assess lake ecosystem health. First, we modified the candidate indices proposed by the U.S. EPA to suit Korean conditions. The modified indices were subjected to individual index suitability analysis, correlation analysis with environmental variables, and redundancy analysis among indices, and 19 indices were finally selected. Taxonomic diversity was suggested to be an important indicator for all three taxonomic groups (cladoceran, copepod, rotifer), on the other hand, the indices using biomass for large cladocerans and copepods, while the indices using abundance were suggested for small cladocerans and rotifers.

Gut contents analysis is essential to predict the impact of organisms on food source changes due to variations of the habitat environment. Previous studies of gut content analysis have been conducted using traditional methods, such as visual observation. However, these studies are limited in analyzing food sources because of the digestive process in gut organ. DNA metabarcoding analysis is a useful method to analyze food sources by supplementing these limitations. We sampled marine fish of Pennahia argentata, Larimichthys polyactis, Crangon affinis, Loligo beka and Sepia officinalis from Gwangyang Bay and Yeosu fisheries market for analyzing gut contents by applying DNA metabarcoding analysis. 18S rRNA v9 primer was used for analyzing food source by DNA metabarcoding. Network and two-way clustering analyses characterized the relationship between organisms and food sources. As a result of comparing metabarcoding of gut contents for P. argentata between sampled from Gwangyang Bay and the fisheries market, fish and Copepoda were analyzed as common food sources. In addition, Decapoda and Copepoda were analyzed as common food sources for L. polyactis and C. affinis, respectively. Copepoda was analyzed as the primary food source for L. beka and S. officinalis. These study results demonstrated that gut contents analysis using DNA metabarcoding reflects diverse and detailed information of biological food sources in the aquatic environment. In addition, it will be possible to provide biological information in the gut to identify key food sources by applying it to the research on the food web in the ecosystem.

Research on food sources through DNA metabarcoding is being used for various organisms based on high resolution and reproducibility. In the study, we investigated the difference in food sources between pre and post-starving in the three bivalve species (Anemina acaeformis, Anodonta woodiana, and Unio douglasiae) through DNA metabarcoding using 18S rRNA V9 primer. The food source of pre-starving appeared in 87 genera, 71 families, 51 orders, 35 classes, and 22 phyla. The primary food sources were the zoo and phytoplankton, including Chlamydomonadales, Euglenales, Ploima, Sphaeropleales, and Stephanodiscales. However, all zoo and phytoplankton were not observed after starving except Schizopyrenida and Rotifera. In Levin’s niche breadth analysis, the Bi index of A. woodiana is 0.3, which was higher than A. acaeformis (0.14) and U. douglasiae (0.21), indicating that they feed on various food sources. The niche overlap of A. acaeformis was measured as 0.78 in A. woodiana, 0.7 in U. douglasiae showing a relative high value compared to other bivalves. The trophic level of A. acaeformis, A. woodiana, and U. douglasiae based on the food source information were investigated as 2.0, 2.0, and 2.5, respectively. The results of the previous study on the trophic level using stable isotopes showed 1.8 to 2.4 values were similar to the results of this study. These results suggest that DNA metabarcoding can be an effective analyzing tool for the gut content in the bivalves.

Recently, with the development of genetic technology, interest in environmental DNA (eDNA) to study biodiversity according to molecular biological approaches is increasing. Environmental DNA has many advantages over traditional research methods for biological communities distributed in the environment but highly depends on the established base sequence database. This study conducted a comprehensive analysis of the habitat status and classification at the genus level, which is mainly used in eDNA (12S rRNA, 16S rRNA, 18S rRNA, COI, and CYTB), focusing on Korean registration taxon groups (phytoplankton, zooplankton, macroinvertebrates, and fish). As a result, phytoplankton and zooplankton showed the highest taxa proportion in 18S rRNA, and macroinvertebrates observed the highest ratio in the nucleotide sequence database in COI. In fish, all genes except 18S rRNA showed a high taxon ratio. Based on the Korean registration taxon group, the gene construction of the top 20 genera according to bio density observed that most of the phytoplankton were registered in 18S rRNA, and the most significant number of COI nucleotide sequences were established in macroinvertebrates. In addition, it was confirmed that there is a nucleotide sequence for the top 20 genera in 12S rRNA, 16S rRNA, and CYTB in fish. These results provided comprehensive information on the genes suitable for eDNA research for each taxon group.

Sampling gears for collecting fish are diverse, and the community of fish varies according to the selection and characteristics of the sampling gears. The present study compared the characteristics of fish communities in Yedang reservoir using four sampling gears (kick net, cast net, gill net, and fyke net). The kick net and cast net were inefficient in collecting the number of individuals. However, they increased the species diversity of fish inhabiting the waterfront. Although not many individuals were collected, the gill net mainly collected large fish. The largest number of individuals was collected in the fyke net, and the dominance was high due to the high species selectivity. Through Self-Organizing Map (SOM) analysis, large fish were collected in the gill net, whereas small fish were collected in the fyke net. The characteristics and efficiency of the fish differed depending on the sampling gears. It is expected that researchers will need to use it appropriately according to the characteristics of the sampling gears when investigating the fish community.

An estuary is a water ecosystem with a high abundance of the species diversity, due to a variety of complex physicochemical factors of the area where freshwater and ocean mixed. The identification of Corbicula species in the estuary environments is difficult because of various morphological characteristics. In this study, we provide taxonomic information on Corbicula species with taxonomic difficulties using morphological and genetic analysis. This study was conducted on clams from the Seomjin River-Gwangyang Bay, one of the major production area of marsh clam in Korea. As a result, we characterized Cytocrome C Oxidase subunit I (COI) sequences of the Corbicula. The 636 bp nucleotide sequences of COI have 98% homology among Corbicula species collected from 2 sites of Seomjin River-Gwangyang Bay. The phylogenetic analysis with 17 species of Corbicula indicated that most of the species collected from Seomjin River-Gwangyang Bay were brackish water clam (Corbicula japonica), and only one Asian clam (Corbicula fluminea). The evolutionary distance between C. japonica and C. fluminea was less than 0.003. Therefore, it was confirmed that C. japonica is phylogenetically closely related to C. fluminea. In 9 species of Cyrenidae, phylogenetic tree was classified into three lineages. These results will be used as an important data for an identification of clam species by providing genetic information for Corbicula species with a morphological diversity. Key words: Corbicula japonica, cytochrome c oxidase subunit I (

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, middleflow, 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.

In this study, 46 reservoirs in South Korea were characterized based on heavy metal concentration in sediments. We analyzed the relationship between heavy metal concentrations, physicochemical water quality and hydromorphological factors in each reservoir. Study reservoirs were classified into five groups of reservoirs, by hierarchical cluster analysis based on the similarities of heavy metal concentration. Group 1 had the most severe sediment heavy metal contamination among the groups, whereas Groups 2 and 3 showed low levels of heavy metal contamination. Group 4 displayed high value of Ni, and Group 5 showed high contamination of Pb, Cu, Cr, Ni, and Hg. Groups 1 and 5, which had high concentration of heavy metals in sediments, showed a high density of mines in the catchment of reservoirs. Heavy metal concentration was high in reservoirs with large capacity or the ones located at higher elevation, and also highly related with number of mines in the catchment of reservoir. This study can contribute to the systematic management of sediment heavy metals in reservoirs.

The fish community in the Seomjin River-Seomjin River Estuary-Gwangyang Bay coast continuum was investigated three times from March 2019 to October 2019. The collected species at the eight sites during the survey period were 49 species belonging to 31 families, including two endangered species. According to Bray-Curtis similarities, observations were divided into four groups based on the fish community composition; two groups (group 1, 2) and two uncategorized groups (group 3, 4). ANOSIM based on spatial and temporal groupings indicated that the spatial differences in fish communities (R=0.398, P=0.001) were relatively more important than the temporal differences (analysis of similarities, R=0.273, P=0.002). In particular, there were significant differences between groups 1 and 2 (analysis of similarities, R=0.556, P=0.001), and similarity percentage analysis revealed that Argyrosomus argentatus (9.4%), Favonigobius gymnauchen (6.9%) and Konosirus punctatus (5.9%) contributed to these differences of fish assemblages for each group. The fish fauna distributed in the Seomjin River-Gwangyang Bay ecosystem were spatially divided and the number of species and number of individuals showed seasonal differences. This study could be a basis for understanding changes in the fish community and implementing conservation and management strategies on major species within a continuous environment of the river-estuary-ocean continuum.

A pump-type eDNA filtering system that can control voltage and hydraulic pressure respectively has been developed, and applied a filter case that can filter out without damaging the filter. The filtering performance of the developed system was evaluated by comparing the eDNA concentration with the conventional vacuum-pressured filtering method at the catchment conduit intake reservoir. The developed system was divided into a voltage control (manual pump system) method and a pressure control (automatic pump system) method, and the pressure was measured during filtering and the pressure change of each system was compared. The voltage control method started with 65 [KPa] at the beginning of the filtering, and as the filtering time elapsed, the amount of filtrate accumulated in the filter increased, so the pressure gradually increased. As a result of controlling the pressure control method to maintain a constant pressure according to the designed algorithm, there was a difference in the width of the hydraulic pressure fluctuation during the filtering process according to the feedback time of the hydraulic pressure sensor, and it was confirmed that the pressure was converged to the target pressure. The filtering performance of the developed system was confirmed by measuring the eDNA concentration and comparing the voltage control method and the hydraulic control method with the control group. The voltage control method obtained similar results to the control group, but the hydraulic control method showed lower results than the control group. It is considered that the low eDNA concentration in the hydraulic control method is due to the large pressure deviation during filtering and maintaining a constant pressure during the filtering process. Therefore, rather than maintaining a constant pressure during filtering, it was confirmed that a voltage control method in which the pressure is gradually increased as the filtrate increases with the lapse of filtering time is suitable for collecting eDNA. As a result of comparing the average concentration of eDNA in lentic zone and lotic zone as a control group, it was found to be 96.2 [ng μL-1] and 88.4 [ng μL-1l], respectively. The result of comparing the average concentration of eDNA by the pump method was also high in the lentic zone sample as 90.7 [ng μL-1] and 74.8 [ng μL-1] in the lentic zone and the lotic zone, respectively. The high eDNA concentration in the lentic zone is thought to be due to the influence of microorganisms including the remaining eDNA.

Intertidal mud crab (Macrophthalmus japonicus) is an organism with a hard chitinous exoskeleton and has function for an osmotic control in response to the salinity gradient of seawater. Crustacean exoskeletons change in their natural state in response to environmental factors, such as changes in the pH and water temperature, and the presence of pollutant substances and pathogen infection. In this study, the ecotoxicological effects of irgarol exposure and heavy metal distribution were presented by analyzing the surface roughness of the crab exoskeleton. The exoskeleton surface roughness and variation reduced in M. japonicus exposed to irgarol. In addition, it was confirmed that the surface roughness and variation were changed in the field M. japonicus crab according to the distribution of toxic heavy metals (Cd, Pb, Hg) in marine sediments. This change in the surface roughness of the exoskeleton represents a new end-point of the biological response of the crab according to external environmental stressors. This suggests that it may affect the functional aspects of exoskeleton protection, support, and transport. This approach can be utilized as a useful method for monitoring the aquatic environment as an integrated technology of mechanical engineering and biology.

깔따구 (Diptera: Chironomidae)는 저서성 대형무척추동 물로 환경 및 수질 변화에 민감한 영향을 받는 중요한 환경 지표생물이다. 이러한 깔따구 유충이 정수장에서 본 연구에서는 제주 정수처리장에서 발견된 깔따구 유충의 종을 분류하기 위해 형태 사진 및 COI (cytochrome c oxidase subunit I) Primer로 증폭시킨 DNA의 염기서열을 계통수 분석을 통해 분석을 실시하였다. 정수장 내 수도꼭지와 소화관 등에서 채집된 17개체는 둥근깃깔따구 (O. tamarutilus) 14개체, 타마긴털깔따구 (P. tammaater) 3개체 총 2종으로 확인되었다. 각 깔따구 종의 형태적 특징은 두부, 하순기절, 대악, 안테나, 발톱의 형태적 특징의 분류기로 종 동정하였다. NCBI Genbank에 등록된 깔따구 19종 COI 염기서열을 기반으로 본 연구에서 조사된 17개체의 계통진화적 분석 결과 채집된 깔따구 COI 염기서열이 둥근깃깔따구 (O. tamarutilus)와 타 마긴털깔따구 (P. tammaater) 2종으로 각각 계통군 (clade)를 이루는 것이 확인되었다. 이러한 결과는 정수장 환경별 발견 되는 깔따구 유충의 다양성의 확인과 형태적-유전적 종 동정 분류정보를 바탕으로 수환경 관리 및 평가를 위한 기반 정보로 활용될 것이다.

말쥐치는 북서태평양 해역에 분포하는 군집성 어류로 수산식품으로 이용되는 경제적 가치가 높은 어종이다. 본 연구에서는 서남해에 서식하는 국내산 말쥐치 (Thamnaconus modestus)와 기존에 보고된 유사종 (Thamnaconus septentrionalis) 과의 형태적-유전적 특징을 비교-분석하였다. 이를 위해 서남해에서 채집한 말쥐치의 외부 형태와 골격을 관찰하고, 미토콘드리아 DNA의 cytochrome c oxidase subunit I (COI) 유전자 염기서열을 비교하여 유사종 (T. septentrionalis)과의 계통진화적 연관관계를 분석하였다. 서남해안 말쥐치의 외부 형태는 회갈색 바탕에 몸 전체에 흑갈색 무늬가 불규칙하게 산재된 패턴을 가지며 청록빛의 지느러미가 관찰되었다. 채집한 말쥐치에서 추출한 미토콘드리아DNA의 COI 유전자 분석결과 7종류의 염기서열 변이가 나타났으나 상동성이 전체적으로 98.8% 이상으로 유사 성이 높게 나타났다. 또한 형태적으로 말쥐치 유사종인 T. septentrionalis COI 염기서열 비교와 계통유전학적 분석 결과, 보고된 시퀀스 중 상동성이 99%로 유전적으로 말쥐치로 보여지는 두 종 (JN813099, MW485059)과 상동성 95%로 유사종으로 보이는 두 종 (EF607583, KP267619)이 확인되었다. 말쥐치와 유사종은 계통유전적 분석결과 말쥐치와 유사종의 차이를 확인하였으나 형태적 특징으로 종 분류는 어 려운 상태이다. 따라서 본 연구는 말쥐치의 외부 형태와 내부 골격 및 계통유전학적 정보를 제공함으로 말쥐치와 유사종 (T. septentrionalis)의 분류학적 재검토를 진행하는 데 주요한 정보가 될 것이다.

동물플랑크톤 군집 연구에 DNA 바코딩과 같은 DNA 분 석 기법의 적용은 분류형태학을 기반으로 하는 전통적인 종 동정 시 발생할 수 있는 문제 (e.g. 개체의 표현형 가소성에 의한 오동정, 유사종 및 자매종, 유생 시기의 종 동정의 어려움)를 보완할 수 있다. 최근 DNA 시퀀싱 기술의 발전으로 다양한 수생태계의 동물플랑크톤 군집은 물론, 육안 및 현미경을 통해 구분하는 데 한계가 있는 동물플랑크톤의 위 내용물에 대한 DNA 기반 군집 분석 또한 가능하게 되었으며, 이는 동물플랑크톤의 섭식 먹이원 분석을 통한 생물학적 상호 작용을 이해를 돕는다. 본 논문은 동물플랑크톤 연구에 DNA 분석 기법이 활용된 사례 (e.g. DNA 바코딩을 이용한 계통분 류학적 연구, 메타바코딩을 이용한 군집 분석, 위 내용물 분석)를 소개하고 분석 방법을 요약하여, 최종적으로 향후 이를 활용하고자 하는 연구자들에게 연구 접근성을 높일 수 있도록 방법론적인 기초 지식을 제공하고자 하였다.

국내 생태계의 환경유전자 적용도 가속화되고 있으나 생산된 데이터를 처리하고 분석하는데 한계를 느끼고 있으며, 분석 생산된 생물데이터의 신뢰성에 대한 의구심이 제기되기도 하고 시료 매체 (대상 시료, 물, 공기, 퇴적물, 위내용물, 분변 등) 간의 방법에 따른 차이와 분석 방법의 정량화와 개선 등이 필요한 상태이기도 하다. 따라서 국내 생태계의 환경 유전자를 활용한 생물다양성 연구의 신뢰성과 정확성을 확보하기 위해서는 생태분류학으로 축적된 데이터베이스를 적 극적으로 활용하여 검증 절차를 거치고, 유전자 서열 분석으로 높아진 데이터의 해상력을 전문가들이 검증하는 과정이 반드시 필요하다. 환경유전자 연구는 분자생물학적인 기술 적용으로만 해결될 수 없으며, 생산된 데이터의 신뢰성을 확보하기 위한 생태-분류-유전학-인포메틱스 등 학제 간의 연구 협력이 중요하며, 다양한 매체를 다루는 연구자들이 함께 접근할 수 있는 정보 공유 플랫폼이 절실한 분야이며, 발전의 속도도 급격하게 진행될 것이고 축적되는 데이터는 수년 내에 빅테이터로서 성장할 수 있을 것으로 기대된다.

Chironomids are a large group of invertebrates that live in various aquatic habitats. The distribution range of these invertebrates has become varied due to anthropogenic impacts; as such, their distribution can be used as an indicator of environmental health. Adult chironomids are well known in South Korea; however, the larvae have rarely been studied due to difficulties associated with morphological classification. To address this lack of information, we collected larvae from four important rivers in South Korea and summarized their taxonomic morphological characteristics. The antennae, mandible, and mentum were used for larval taxonomic characterization. In this study, we describe the basic morphological features and key pictorial features of 20 species of chironomids, representing 16 genera.

본 연구에서는 2020년 6월에서 9월까지 4개월 동안 우리나라 하천 중 금강 백제보에 주로 서식하는 말조개, 펄조개와 대칭이를 채집하여 서식처 특성을 살펴보았고, 이들의 여과율을 실내 실험을 통하여 측정하여 검량선을 산출하였다. 백제보에서 채집된 말조개, 펄조개, 대칭이는 24시간 동안 평균 154.84 μg L-1의 Chl-a를 제거하였으며, 이는 실내 수조 (2 L) 내의 식물플랑크톤 C. vulgaris (초기 Chl-a=168.34 μg L-1)를 약 24시간 만에 제거할 수 있는 것으로 나타났다. 따라서, 본 연구에서 사용한 말조개, 펄조개, 대칭이가 연평균 4 만 마리가 서식할 경우 (Lee et al., 2020), 6월 한달 동안 예상되는 Chl-a의 저감 효과는 10.55%으로 예측되고 7월의 경우 34.88%, 8월의 경우 20.14%, 9월의 경우 46.21%로 평균 27.94%의 저감 효과를 예상할 수 있다. 이러한 결과는 간접적으로 이매패류가 서식지에서 효과적으로 Chl-a를 제거 할 수 있을 가능성을 제시한다. 실제로 이매패류를 통하여 수생태계의 조류 제어능력을 평가하기 위해서는 이매패류뿐만 아니라 식물플랑크톤, 수생식물, 저서생물, 퇴적물, 유속 등의 작용들을 종합적으로 고려해야 하지만 본 연구에서는 이매패류의 여과율과 이에 따른 Chl-a에 저감율에 기반하여 수생 태계 조류 제어능력을 산정하였다. 본 연구 결과들은 차후 다양한 요인과 관점에서의 통합된 연구에 기초적인 정보를 제공할 것으로 사료된다.