This study summarizes the history of zooplankton research in the Nakdong River basin, Korea, and discusses its main characteristics by topic. A review of major academic search portals revealed 56 studies on zooplankton in the Nakdong River basin, which account for 27.6% of the 203 domestic freshwater zooplankton studies. With the exception of one study conducted before the construction of the estuary barrage, all other research was carried out after the barrage was built. Of the studies, 27 were related to lotic ecosystems, and 29 focused on lentic ecosystems, with research predominantly conducted south of Daegu Metropolitan City. Short-term studies of less than a year were common for lentic ecosystems, while longterm studies were mainly focused on lotic ecosystems. The key research sites were the Mulgeum water intake in the lower Nakdong River and Upo Wetland, the largest inland wetland in Korea, where research periods and zooplankton sampling were most diverse. Research on predation and prey interactions has been ongoing, as zooplankton plays an intermediary role by feeding on phytoplankton and serving as food for juvenile fish. Recent studies show that, since around 2015, the water quality and zooplankton community dynamics around Mulgeum have changed, requiring continuous monitoring. To address this, predictive model analysis, isotope analysis, and indicator analysis, widely used in Nakdong River research, could help develop health indicators for aquatic ecosystems using zooplankton.

The Hangang River, serving as the primary water supply source for the capital region of South Korea, plays a vital role in sustaining regional ecosystems and ensuring water quality. Phytoplankton are integral to the maintenance of aquatic ecosystems and function as bioindicators of water contamination; however, the species-level composition and environmental interactions of phytoplankton in the Hangang River remain inadequately characterized. This study investigated the phytoplankton communities within the Hangang River system across eight sampling stations over eight sampling events from May 2021 to March 2022. A total of 71 species were identified, yielding a density of 3,560 cells mL-1, with Bacillariophyceae (36 species, 2,809 cells mL-1), Chlorophyceae (24 species, 212 cells mL-1), and Cyanophyceae (5 species, 394 cells mL-1) identified as the dominant groups. The most abundant species was Aulacoseira granulata (1,616 cells mL-1, 45.4%), followed by Stephanodiscus hantzschii (420 cells mL-1, 11.8%) and Phormidium tenue (383 cells mL-1, 10.8%). Spatial similarity analysis of the phytoplankton communities revealed three distinct groups: Group A (stations 1-4, upstream), Group B (stations 5-7, midstream), and Group C (station 8, downstream). Seasonal similarity analysis further categorized the communities into three groups: Group A (May, July, August, and October 2021), Group B (November and December 2021), and Group C (February and March 2022). These findings contribute to a deeper understanding of the spatial and seasonal dynamics of phytoplankton in the Hangang River system.

This study investigated the spatial distribution of dissolved organic carbon and the changes in tidal flat soil characteristics following the flooding season in the closed estuary of the Geumgang River basin. We found that after the flooding season, a brackish water area expanded due to increased river discharge, which also introduced low concentrations of dissolved organic carbon from the river. Dissolved inorganic carbon predominantly originated from the sea in proportion to salinity, indicating that in the closed estuary area, dissolved carbon supplied from the sea remained a significant source even after the flooding season. Additionally, a substantial amount of tidally transported silt and clay was deposited near the estuary dam after the flood, and its effects continued to influence the sediment characteristics downstream in the intertidal zone. As an empirical study in the closed estuary, our results are expected to contribute to conservation measures for the World Heritage Site in the area.

River discharge is a crucial indicator of climate change and requires accurate and continuous estimation for effective water resource management and environmental monitoring. This study used satellite gravimetry data to estimate river discharge in major basins with high discharge volumes, specifically the Congo and Orinoco basins. By enhancing the spatial resolution of gravity data through advanced post-processing techniques, including forward modeling and river routing schemes, we effectively detected changes in the water mass stored within river channels. Additionally, signals from surrounding regions were statistically removed using the Empirical Orthogonal Function (EOF) analysis to isolate river-specific discharge signals. These refined signals were then converted into river discharge data through seasonal calibration using the modeled discharge data. Our results demonstrate that this method yields accurate and reliable discharge estimates comparable to in-situ measurements from gauge stations, even without ground-based surveys such as an Acoustic Doppler Current Profiler (ADCP) field campaigns. This research highlights the significant potential of satellite-based gravity data as an alternative to traditional ground surveys, providing practical information on the hydrological status of regions associated with large-scale river systems.

강으로부터 해양으로 유입되는 퇴적물은 유역분지의 지질, 지리, 지형, 기후 등의 영향을 반영하며, 육상 유역분 지에서 퇴적물 생성 과정에서 수반되는 화학적 풍화는 대기 중 이산화탄소 농도를 조절하는 데에 중요한 역할을 하는 것으로 알려져 있다. 본 연구에서는 한반도 남해안 낙동강 하구 인근 해저 표층 퇴적물의 지화학 조성을 이용하여 화 학적 풍화의 강도와 퇴적물의 기원지에 분포하는 암석의 조성을 추정하였다. 연구 시료의 화학적 풍화 강도는 중간에 낮은 정도(평균 Chemical Index of Alteration=68)이며 A-CN-K 도표에서 추정한 풍화의 추세는 퇴적물의 기원지 성분 이 평균적인 상부 대륙지각과 매우 유사한 것으로 보인다. 이는 낙동강 유역분지에 분포하는 중생대 화강암류와 경상누 층군 퇴적암이 혼합된 성분을 반영하는 것으로 판단되기 때문에 연구 대상인 퇴적물이 낙동강 하구로부터 유입되는 퇴 적물의 성분을 대표하는 것으로 해석한다. 표층 퇴적물의 희토류원소는 분화된 경희토류-중희토류의 비와 음의 Eu 이상 을 나타내어 상부 대륙지각과 매우 유사하다. 본 연구의 결과를 전 세계 강 하구 퇴적물 자료 및 국내의 큰 강 자료와 비교하였으며, 이를 통하여 지질 및 지형의 잠재적인 영향을 고려할 수 있다.

The Yeongsan River is a prominent inland waterway, alongside the Han River, Nakdong River, and Geum River in South Korea. Numerous bacterial strains were isolated from the Yeongsan River basin for a comprehensive investigation into indigenous prokaryotic species conducted between 2020 and 2023. These bacterial strains were identified using 16S rRNA gene sequencing, wherein 45 bacterial strains shared >98.7% sequence similarities with bacterial species not recorded in Korea thus far. Therefore, this study aimed to catalogue aforementioned unrecorded species and characterize them contingent upon their Gram nature, colony and cell morphologies, biochemical properties, and phylogenetic positions. These bacterial species were determined to be phylogenetically diverse. They were categorized into nine classes, 18 orders, and 25 families. These previously unrecorded species were classified into the following genera and classes: Chitinophaga (class Chitinophagia); Flavobacterium (class Flavobacteriia); Rhodopseudomonas, Gemmobacter, Paracoccus, Azospirillum, Sphingomonas, Novosphingobium, Sphingorhabdus, and Erythrobacter (class Alphaproteobacteria); Bordetella, Pararobbsia, Polynucleobacter, Rhodoferax, Aquabacterium, Malikia, Comamonas, Ideonella, Paucibacter, Undibacterium, Cupriavidus, and Thauera (class Betaproteobacteria); Pectobacterium, Arenimonas, Lysobacter, and Luteimonas (class Gammaproteobacteria); Luteolibacter (class Verrucomicrobiia); Mycolicibacterium, Angustibacter, Ornithinibacter, Janibacter, Schumannella, Aurantimicrobium, Luedemannella, Nocardioides, and Propionicimonas (class Actinomycetes); Geothrix (class Holophagae); and Lactococcus (class Bacilli).

Recently, Korean government has incorporated the assessment and restoration of river continuity as a key component of its integrated water management policy. While, methodologies for evaluating discontinuities and degradation, as well as the procedures for assessment and restoration, have been developed and proposed, there is a need for further improvement. Therefore, further research is required to establish a conceptual framework for continuity specific to domestic river ecosystems and to formulate appropriate assessment methods and restoration strategies. In this study we conduct a comparative analysis of the concepts, restoration approaches, and comprehensive evaluation methods for river continuity as proposed by Japan, the United States, and the European Union (EU), all of which have long-standing frameworks for river continuity assessment and restoration projects. Each country demonstrates distinct objectives and guidelines: Japan emphasizes habitat continuity within the context of river and watershed continuity, the United States integrates continuity as a tool for watershed management, and the EU prioritizes biodiversity conservation by advocating for the removal of artificial barriers and promoting the restoration of free-flowing rivers (FFR). By investigating these international examples, this study provides insights that can guide the development of long-term strategies and evaluation criteria for securing aquatic ecosystem continuity in Korea.

As part of the research program “Freshwater Prokaryotic Organisms Research and Discovery,” freshwater samples were collected from the Nakdonggang River. After plating the samples on several culture media and incubating aerobically, approximately 900 bacterial strains were isolated and identified using 16S rRNA gene sequences. Among the bacterial isolates showing higher than 98.7% 16S rRNA gene sequence similarity with those of already confirmed bacterial species previously unreported in Korea, 29 strains were selected. These strains were phylogenetically diverse and belonged to 3 phyla, 6 classes, 13 orders, and 21 genera. At the genus level, these previously unreported species were found to be affiliated with Novosphingobium, Sphingomonas, Polymorphobacter, Croceibacterium, Devosia, Endobacterium, Agaricicola, Bradyrhizobium, Paracoccus, and Pseudotabrizicola of the class Alphaproteobacteria; Undibacterium, Azonexus, and Dechloromonas of the class Betaproteobacteria; Acinetobacter and Budvicia of the class Gammaproteobacteria; Streptomyces, Nocardioides, Mycobacterium, and Cellulomonas of the phylum Actinomycetota; Flavobacterium and Pedobacter of the phylum Bacteroidota. These species were further characterized by examining their Gram reaction, colony and cell morphologies, biochemical properties, and phylogenetic positions. Detailed descriptions of these 29 previously unreported species are provided.

섬강 상류의 어류상 변화와 어류군집 특성을 밝히기 위해 2018년부터 2020년까지 조사를 실시하였다. 조사기간 동안 35개 지점을 조사한 결과, 채집된 어류는 12과 40종 7,817개체였다. 출현종 중 우점종은 참갈겨니(Zacco koreanus, 34.5%), 아우점종은 피라미(Z. platypus, 28.7%)였고, 그 다음으로 버들치(Rhynchocypris oxycephalus, 10.2%), 돌고기 (Pungtungia herzi, 5.3%), 긴몰개(Squalidus gracilis majimae, 4.3%), 참종개(Iksookimia koreensis, 2.1%), 참마자 (Hemibarbus longirostris, 1.6%), 모래무지(Pseudogobio esocinus, 1.5%) 돌마자(Microphysogobio yaluensis, 1.4%), 한강납줄개(Rhodeus pseudosericeus, 1.4%) 등의 순으로 우세하였다. 법정보호종은 환경부지정 멸종위기 야생생물 II급인 한강납줄개와 묵납자루(Acheilognathus signifer), 돌상어(Gobiobotia brevibarba), 둑중개(Cottus koreanus) 4종이 출현하였는데, 주로 한강납줄개와 묵납자루, 돌상어는 중·하류에, 둑중개는 최상류에 서식하고 있었다. 출현종 중 한국고유 종은 19종(고유화율 47.5%)이었고, 기후변화민감종(냉수성 어종)은 둑중개 1종, 외래어종은 떡붕어(Carassius cuvieri)와 배스(Micropterus salmoides) 2종이 확인되었다. 군집분석 결과, 대체로 상류에서 하류로 갈수록 우점도는 낮아지고 다양도와 풍부도는 높아지는 경향을 보였으며, 군집구조는 크게 최상류, 상류, 중하류, 호수로 구분되었다. 섬강 상류는 횡성댐이 건설되면서 직·간접적으로 어류군집에 큰 영향을 미쳤는데, 댐 건설 직후 멸종위기종 묵납자루와 한강납줄개, 돌상어 서식지 및 개체수가 급격히 감소하고 수몰지역은 유수성 어류에서 정수성 어류로 변화되었다. 약 20년이 지난 현재, 서식지가 안정화 되면서 서식하는 어류가 증가하고 급격히 감소하였던 멸종위기종 한강납줄개와 돌상어의 서식지 및 개체수가 증가하였다. 또한 하천건강성(FAI)은 27개 지점은 매우 좋음(A), 7개 지점은 좋음(B), 1개 지점은 보통(C)으로 평가되어 비교적 우수하였다. 하지만 멸종위기종 묵납자루는 댐 공사 및 하천공사로 지역절멸에 처해 있고, 둑중개는 하천공사로 개체수가 심각하게 감소하였으며, 횡성호에서 생태계교란 생물 배스의 서식이 확인되어 우려되었다. 따라서 섬강 상류의 안정적인 어류 서식을 위해서는 무분별한 하천공사를 지양하고, 멸종위기종 묵납자루는 시급히 복원정책이 필요하며, 생태계교란 생물 배스의 확산을 방지할 수 있는 관리방안이 요구되었다.

Daemadeung, located in the estuary of the Nakdong River, is formed by sand dunes and possesses well-developed intertidal flats. This study aimed to investigate the habitat of benthic microalgae, photosynthetic pigments, and photosynthetic efficiency in the intertidal flats of Daemadeung from January to December 2011. The inorganic nitrogen content in the sediment pore water was primarily composed of ammonium, while nitrate+nitrite was dominant in the upper layer water. The concentration of chlorophyll a and fucoxanthin in the sediment surface was significantly higher than the mean of all the sediment layer. The average Fv/Fm of benthic microalgae during the entire survey period was 0.52±0.03, with the highest value (0.61±0.08) observed in February. The rETRmax showed a seasonal trend, being high from spring to early autumn (April to October) and low from winter to early spring (January to March, November, December), with the highest value (153.05±2.30 μmol electrons m-2 s-1) in July and the lowest (38.49±5.17 μmol electrons m-2 s-1) in January. The average Fv/Fm of diurnal microalgae was 0.48±0.03, with the highest value (0.61±0.08) observed at noon. The rETRmax showed a highest peak at noon (54.24±11.35 μmol electrons m-2 s-1) and reached its lowest point at 16:00 (26.17±4.75 μmol electrons m-2 s-1). These findings suggest that the productivity of benthic microalgae varies significantly depending on the survey time and sediment depth. Therefore, to quantify the productivity of benthic microalgae using Diving-PAM, surveys should be conducted based on tidal conditions, and simultaneous pigment analysis of sediment layers should also be performed.

안양천의 어류 군집 특성과 어류상에 대한 수질의 영향을 밝히기 위해 2022년 4~6월과 8~10월에 20개 지점을 2회 조사하였다. 조사 기간 동안 채집된 어류는 5목 10과 34종 3,186개체였다. 우점종은 피라미(Zacco platypus, 43.4%) 였고, 아우점종은 붕어(Carassius auratus, 10.1%), 그 다음으로 잉어(Cyprinus carpio, 7.6%), 참갈겨니(Zacco koreanus, 6.2%), 돌고기(Pungtungia herzi, 5.2%), 대륙송사리(Oryzias sinensis, 5.1%), 참붕어(Pseudorasbora parva, 4.7%), 긴몰개(Squalidus gracilis majimae, 4.4%), 버들치(Rhynchocypris oxycephalus, 3.5%), 치리(Hemiculter eigenmanni, 3.3%), 흰줄납줄개(Rhodeus ocellatus, 1.4%), 가숭어(Chelon haematocheilus, 1.0%) 등의 순으로 우세하 게 출현하였다. 출현종 중 한국고유종은 각시붕어(Rhodeus uyekii), 긴몰개, 몰개(Squalidus japonicus coreanus), 참갈 겨니, 얼록동사리(Odontobutis interrupta) 5종(14.7%)이었고, 외래종은 이스라엘잉어(Cyprinus carpio Israeli type), 블루길(Lepomis macrochirus), 배스(Micropterus salmoides), 구피(Poecilia reticulata) 4종(11.8%)이었다. 어류 군집 분석 결과, 우점도는 상류가 높았고 하류로 가면서 낮아졌으며, 다양도와 풍부도, 균등도는 본류보다 지류에서 높게 나타나는 경향을 보였다. 하천건강성을 평가한 결과, 7개 지점에서 보통(C), 8개 지점에서 나쁨(D), 5개 지점에서 매우 나쁨(E)으로 평가되어 좋지 않았다. 수질은 8개 지점을 평가한 결과, 4개 지점은 보통(III), 2개 지점은 나쁨(V), 1개 지점은 약간 나쁨(IV), 1개 지점은 약간 좋음(II)으로 평가되어, 전체적인 수질은 나쁘게 나타났으며, 수질이 하천건 강성과 어류의 서식에 큰 영향을 미치고 있는 것으로 추정되었다. 또한 안양천에 어도가 없는 보가 많이 설치되어 있어 어류의 이동에 장애물로 작용하고 있었다. 따라서 하천건강성을 높이고 안정적인 어류의 서식을 위해서는 수질을 개선할 수 있는 체계적인 관리방안이 필요하고 보에 어도 설치가 요구되었다.

Compound characters in oracle bone inscriptions refer to the form of two or three oracle bone characters combined together. These characters, formed after combination, are called compound characters and represent one of the structural features of oracle bone scripts. The phenomenon of compound characters is prevalent among river names in oracle bone inscriptions. Based on this observation, we propose that the formation of river names in oracle bone inscriptions was initially the combinations of geographic names and rivers, and these compound character forms have generally gone through a development process from separate characters to compound characters. Through the study of the structure formation of river names in oracle bone inscriptions, a deeper understanding of the people’s perceptions of river systems and geographical environments during the Shang Dynasty can be obtained, as well as the relationship between geographic names and rivers.

본 연구는 소양강댐 하류에서 서식하는 생태계교란 생물 종인 브라운송어와 그 먹이원으로 이용되는 저서성 대형무척추동물에 대한 파악을 위해 2022년부터 2023년까지 총 8회에 걸쳐 소양강댐 하류(St.1~St.3)와 지류 (St.4)에 대해 브라운송어와 공서종, 브라운송어의 위 내용물, 저서성 대형무척추동물의 종조성 및 기능군 분석을 실시하였다. 저서성 대형무척추동물의 경우, 하루살이목에서 가장 많은 분류군이 확인되었으며(27.1%), 그 중 붙는 무리(CL)와 헤엄치는 무리(SW)가 높은 비율을 차지하는 것으로 확인되었다. 브라운송어 채집 결과, 전장은 26∼246mm까지 총 105개체가 채집되었으며, 전장-체중 관계의 매개변수 b값이 3을 초과하여 안정적인 성장이 이루어지는 것으로 확인되었다. 브라운송어의 위 내용물에 대한 먹이원 분석 결과, 빙어(0.2%, TL: 246mm)와 육상곤충(2.7%, TL: 154mm, 183∼185mm)을 섭식한 개체는 매우 적었으며 상대적으로 전장이 큰 개체에서 확인 되었다. 대부분 수서곤충(73.8%)과 물 속에서 서식하는 비곤충류(23.3%)를 섭식하는 것으로 나타났다. 브라운 송어의 전장에 따른 먹이 섭식 패턴을 파악하기 위해 위 내용물에서 확인된 종들과의 상관분석을 실시한 결과, 브라운송어의 먹이원 중 유수성 환경 선호 종들의 경우 전장과 양의 상관관계(p<0.05)를 나타낸 반면, 모래 기질 이하의 흐름이 적은 서식처를 선호하는 종들의 경우 전장과 음의 상관관계(p<0.05)를 나타냈다.

The goal of this study was to provide basic data necessary for managing fish in the Seomgang River by confirming diversity of fish species in the Seomgang River and determining the degree of change in fish species through a comparison with earlier related work. Growth rate, obesity level, and temporal and spatial reproductive capacities were analyzed to determine growth characteristics of dominant species. Fish fauna and structure of the fish community were surveyed at three different time points from October of 2020 to August of 2021 at eight sites. In addition, growth characteristics of Zacco platypus from June of 2021 to July of 2022 at four sites were determined. A total of 3,999 individuals, 43 species, and ten families of fish were identified. Among these species, 19 (44.19%) were Korean endemic species and four (9.30%) were endangered species. The dominant species was Z. platypus. Pungtungia herzi was identified as a subdominant species. An analysis of length-weight relationships and condition factor (k) of Z. platypus confirmed a good state of growth. As a result of a frequency analysis of the total length, the life cycle of the Z. platypus population living in the Seomgang River was found to be stable. According to gonadosomatic index (GSI) analysis, the spawning season of Z. platypus was estimated to occur after May, consistent with the literature.