Diatoms, which are reported to have over 18,000 species worldwide and approximately 2,400 species in Korea, can be found in various environments including freshwater, seawater, and wetlands. They are particularly valuable for understanding global environmental changes throughout history due to their ability to maintain their shape for extended periods of time. Instead of collecting floating diatoms using nets, low-layer substrates such as gravel and leaves, as well as sedimentary surface layers, were gathered in order to identify attached diatom species. This is because attached diatoms demonstrate higher species diversity compared to floating diatoms. In this study, seven previously unrecorded diatoms were discovered in various domestic freshwater environments. Two species were found in reservoirs (Eunotia yanomami, Gomphonella pseudookunoi), two in parasitic cones (Eunotia carverenensis, Luticola minor), two in rivers (Cavinula maculata and Prestauroneis integra), and one (Surirella brebissonii var. kuetzingii) in a lagoon. The shapes, structures, and morphological characteristics of each diatom were identified using electron microscopy.

The Bayesian algorithm model is a model algorithm that calculates probabilities based on input data and is mainly used for complex disasters, water quality management, the ecological structure between living things or living-non-living factors. In this study, we analyzed the main factors affected Korean Estuary Trophic Diatom Index (KETDI) change based on the Bayesian network analysis using the diatom community and physicochemical factors in the domestic estuarine aquatic ecosystem. For Bayesian analysis, estuarine diatom habitat data and estuarine aquatic diatom health (2008~2019) data were used. Data were classified into habitat, physical, chemical, and biological factors. Each data was input to the Bayesian network model (GeNIE model) and performed estuary aquatic network analysis along with the nationwide and each coast. From 2008 to 2019, a total of 625 taxa of diatoms were identified, consisting of 2 orders, 5 suborders, 18 families, 141 genera, 595 species, 29 varieties, and 1 species. Nitzschia inconspicua had the highest cumulative cell density, followed by Nitzschia palea, Pseudostaurosira elliptica and Achnanthidium minutissimum. As a result of analyzing the ecological network of diatom health assessment in the estuary ecosystem using the Bayesian network model, the biological factor was the most sensitive factor influencing the health assessment score was. In contrast, the habitat and physicochemical factors had relatively low sensitivity. The most sensitive taxa of diatoms to the assessment of estuarine aquatic health were Nitzschia inconspicua, N. fonticola, Achnanthes convergens, and Pseudostaurosira elliptica. In addition, the ratio of industrial area and cattle shed near the habitat was sensitively linked to the health assessment. The major taxa sensitive to diatom health evaluation differed according to coast. Bayesian network analysis was useful to identify major variables including diatom taxa affecting aquatic health even in complex ecological structures such as estuary ecosystems. In addition, it is possible to identify the restoration target accurately when restoring the consequently damaged estuary aquatic ecosystem.

The infection of marine diatom Coscinodiscus wailesii by a parasitic protist from the Yongho Bay of Busan, Korea was observed during the diatom bloom events in 2017 through 2018. The morphological and molecular features suggested that the parasitic nanoflagellate Pirsonia diadema was responsible for the infection. During the study period, the parasite prevalence ranged from 0.3% to 3.3%, and infected C. wailesii cells were observed only at surface seawater temperatures ranging between 10.9 and 19.9°C, although the host population appeared at temperatures above 25°C. The parasite and host system was successfully established as cultures. Using the cultures, we determined the morphological features over the infection cycle, parasite generation time, parasite prevalence as a function of inoculum size, and zoospore infectivity and survival time. The diatom C. wailesii was readily infected by the parasite P. diadema, with a parasite prevalence reaching up to 100% and a zoospore to host inoculum ratio above 20 : 1. The survival and infectivity of the parasite zoospores decreased with age. While the zoospores could survive up to 88 hours, they quickly lost their ability to infect after 48 hours. These results could lead to a better understanding of the biology and ecology of the parasitoid infecting the giant-sized diatoms in coastal waters.

Upo Wetland is the largest riverine wetland in Korea which has been inscribed on the Ramsar List of Wetlands of International Importance in 1998. In this study, sedimentological study was carried out in order to understand the environmental changes in Upo Wetland during the Holocene. The drilling work for recovering the Quaternary sediments was conducted on the inner part (UPW17-01, UPW17-02, and UPW17-03) and the outer part (UPL17-01, UPL17-02) of the Upo Wetland. The recovered sediments are commonly characterized by gravel-dominated deposits in the lower part and silty clay-dominated deposits in the middle to upper parts respectively, which are seemed to be changed from fluvial to palustrine/lacustrine environments around 4,000 cal yr BP. In order to establish the Holocene diatoms distribution from Upo Wetland, we identified 63 diatom taxa. Of these, 14 species were new records for Korea: Gomphonema consector, Gomphonema jadwigiae, Hantzschia abundans, Luticola pseudomurrayi, Luticola spauldingiae, Neidium suboblongum, Ninastrelnikovia gibbosa, Oricymba rhynchocephala, Pinnularia borealis var. lanceolata, Pinnularia latarea, Pinnularia paliobducta, Pinnularia saprophila, Sellaphora laevissima, Stauroneis pseudoschimanskii. All identified diatom species are illustrated by high-quality scanning electron microscopic and light microscopic microphotographs. The ecological habitat for all taxa are presented.

Irgarol과 diuron에 각각 노출된 해산규조류(Skeletonema costatum)의 개체군 성장률(r )을 분석 하여 독성평가를 실시하였다. S. costatum을 irgarol (0, 0.31, 0.63, 1.25, 2.5, 5 μg l-1)과 diuron (0, 7.81, 15.63, 31.25, 62.5, 125 μg l-1)에 각각 96시간 노출하여 r 을 계산하였고, 대조구의 r 은 0.04 이상으로 시험기준에 적합하였다. S. costatum의 r은 irgarol에서 0.63 μg l-1, diuron은 15.63 μg l-1 이상에서 대조구 대비 유의하게 감소하기 시작하여 irgarol과 diuron의 농도가 증가할수록 r이 감소하는 농도의존적인 반응을 나타냈고, 시험 최고농도 5와 125 μg l-1에서 r이 대조구 대비 80% 이상 감소하였다. Irgarol과 diuron에 노출시킨 S. costatum r의 반수영향농도(EC50)는 1.09, 45.45 μg l-1, 무영향농도(NOEC)는 0.31, 7.81 μg l-1, 최소영향농도(LOEC)는 0.63, 15.63 μg l-1으로 나타났으며, EC50 기준으로 irgarol이 diuron보다 독성이 큰 것으로 나타났다. 본 연구결과로 해양 생태계에서 Irgarol과 diuron의 농도가 0.63과 15.63 μg l-1 이상이 되면, 해산 규조류 S. costatum 의 r은 독성영향을 받을 것으로 판단된다. 또한, 독성 값으로 제시된 결과들은 irgarol과 diuron 의 기준농도 설정을 위한 기초자료로 유용하게 활용될 것이다.

Skeletonema pseudocostatum의 세포는 규산질 성분의 돌기에 의한 사슬 형태로, 길이는 6~17.3 μm였고, 엽록체는 세포 당 1~2개를 포함하고 있었다. 주사전자현미경 관찰결과 Skeletonema 종을 구분할 수 있는 가장자리 받침돌기끝 (terminal fultoportula process)은 끝이 갈라지거나, 갈고리 모양이었고, 길이가 1.67±0.5 μm이고, 개각의 가장자리에 위치해 있으며, 개수는 8.10±1.1개로 개각의 크기에 따라 다양하게 나타났다. 말단세포 입술돌기 (terminal rimoportula process)는 두꺼운 원통형의 나팔관 모양으로, 개각의 중앙 근처에 위치하였고, 길이는 1.1±0.6 μm 였으며, 개수는 1개였다. 연결세포 받침돌기 (intercalary fultoportula process)는 대부분 1 : 1 결합으로 서로 맞물려있는 형태였고, 1 : 2 결합도 종종 발견되었다. 계통분석 결과는 형태적 특징이 유사한 종 간의 유전학적 거리가 가깝다는 것을 나타냈고, 지리적 기원이 다른 동일 종의 경우, 유전적 차이를 보이지 않았다. 이는 S. pseudocostatum은 지리적 위치와 상관없이 유전적 차이가 나타나지 않는 단일계통 (monophyly)이라는 것을 의미한다.

낙동강에 위치한 신규조성 습지의 현황 파악 및 관리 방안 마련을 위한 기초연구의 일환으로 부착규조류의 서식현황과 종다양성을 분석하고 부착돌말영양지수(TDI, Trophic Diatom Index)의 적용가능성을 평가하였다. 조사 기간 동안, 부착규조류는 총 38과 173종이 출현하였으며, 봄과 가을에 각각 156종, 154종으로 비슷한 종수를 나타냈다. 자기조직화지도(SOM)를 활용한 분석 결과, 부착규조류의 분포는 각 습지의 영양염류의 농도와 강우 등의 환경요인에 따라 영향 받는 것으로 나타났다. 클러스터 1의 경우, 대부분 가을시기이며, 총인과 총질소 등의 영양염류의 농도와 부착규조류의 종수 및 풍부도가 낮음에도 불구하고, 부착돌말영양지수가 높은 지점들로 구성되었다. 이와 반대로, 클러스터 4는 봄시기의 지점들이며, 총질소가 높음에도 불구하고 부착돌말영양지수가 낮은 특징을 보였다. 신규조성 습지 대부분이 유입·유출구 기능이 원활하지 않은 점을 감안하면, 여름철에 증가된 유량은 가을철에 영양염류 값을 감소시키며, 탁도 증가로 인해 빛의 유입이 원활하지 않아 부착규조 류의 종수와 풍부도가 낮아진다. 이와 반대로, 봄철에는 낮은 수위로 인해 부착규조류가 부착할 수 있는 기질표면이 부족하며, 호오탁성 종이 정착 및 발달하기에 이른 시기이기 때문에 부착돌말영양지수 값이 낮게 측정된다. 다양한 기존 연구에서, 부착돌말영양지수를 서식환경 및 수질 평가지표로 활용하고 있으나, 본 습지는 흐름이 적고 정체수역에 가깝기 때문에 대부분 영양염류 농도가 높아 부착돌말영양지수의 평가지표 가치성은 낮은 것으로 판단된다. 여름강우나 유입·유출 조절부의 기능이 부착규조류의 종다양성과 분포에 영향을 미치는 점을 종합적으로 감안한 지속적이고 주기적인 추가 조사가 필요하다.

해산규조류 (Skeletonema cosatatum)의 개체군성장률 (r)을 사용하여 연안 유기오염물질인 phenanthrene (PHE) 과 zinc undecylenate (ZU)의 독성평가를 실시하였다. S. costatum을 PHE (0, 25, 50, 100, 200, 300 mg L-1)와 ZU (0, 5, 10, 15, 20, 25 mg L-1)에 각각 96시간 노출한 이후에 r 을 산 출하였고, 대조구의 r 은 0.04보다 높아 시험기준에 적합하였다. S. costatum의 r 은 PHE 50, ZU 10 mg L-1 이상의 농도 에서 대조구 대비 유의하게 감소하기 시작해 PHE와 ZU 의 농도가 증가할수록 감소되는 농도의존성을 나타냈으며, 최고농도인 300과 25 mg L-1 농도에서는 r 이 나타나지 않았다. PHE와 ZU에 노출된 S. costatum r 의 반수영향농도 (EC50)은 136.13, 16.95 mg L-1, 무영향농도 (NOEC)는 25, 5 mg L-1, 최소영향농도 (LOEC)는 50, 10 mg L-1로 나타났다. 본 연구결과, 해양생태계 내에서 S. costatum의 r 은 PHE 50 mg -1, ZU 10 mg L-1 이상의 농도에서 독성영향으로 감소할 것으로 판단되며, PHE와 ZU의 기준농도 설정을 위한 기초자료로 유용하게 사용될 것이다.

수생태계 생물학적 온전성을 평가하기 위하여 국내 하천 및 하구 923개 지점의 자료를 근거로 한국형 다중형 돌말지수 (KMDI)를 개발하고, 이를 금강수계 233개 지점을 대상으로 온전성평가를 실시하여 단일형 돌말지수들과 비교 검토하였다. KMDI의 개발은 1) 먼저 선행문헌들을 참고로 300개 이상의 메트릭을 추출하고, 2) 이 중 설명력이 높은 46개 후보 메트릭을 선택하며, 3) 각 메트릭 값들의 변이성, 중복성, 변별력, 환경에 대한 민감성 등을 검증하고, 최종적으로 5가지의 메트릭을 선정하였다. KMDI는 매트릭의 단순합으로 표현하고, 환경요인들에 대한 신뢰성 검토 결과, 토지이용, BOD, TN, 전기전도도 등에 대해 높은 민감성 및 설명력을 보였으나 단일형 돌말지수들 보다는 동일 지점의 생물학적 온전성은 다소 높게 평가되는 특성을 보였다. 추후 국내는 물론 지역에 상관없이 적용가능한 설명력 높은 매트릭의 발굴 및 정확한 돌말류 분석 연구가 뒷따라야 될 것으로 판단되었다.

River water quality and organisms have a very close relationship with the human living environment and health, so it is very important to ensure and maintain the ecological integrity of the aquatic ecosystem. In that sense, benthic diatoms have relatively little mobility, can explain the effects of long-term exposed pollution sources, and are very suitable indicator organisms for river ecosystem evaluation. Diatom ecologists have been developed various diatom indices to assess water quality and stream ecosystem over the world. However, they so far have insufficient identification of taxa, are strongly regional, and are difficult to apply as they are domestically. Unfortunately, there has not been developed an independent diatom index suitable for the Korean stream. Therefore, management of water quality and aquatic ecosystem suitable for domestic rivers can be made, and development or improvement of comprehensive multivariate diatom index for the integrated assessment of water quality and aquatic ecosystem is urgently needed.

본 연구는 한국 남서해안 갯벌 중 유부도, 곰소만, 임자도, 여자만 갯벌의 저서돌말류 종조성 및 생물량을 알아보기 위해 2016년 8월과 9월에 현장조사를 실시하였다. 유부도 갯벌에서 저서돌말류는 48속 181종, 곰소만 갯벌에서 51속 194종, 임자도 갯벌에서 64속 224종, 여자만 갯벌에서 56속 188종이 출현하였으며, 총 70속 274종이 출현하였다. 분류군 가운데 중심돌말목보다 우상돌말목이 다양하게 출현하였고 우점종은 중심돌말목의 Paralia sulcata와 Navicula spp.였다. 유부도 갯벌의 생물량은 정점별로 18.8~136.1 mg m-2, 곰소만 갯벌 31.9~215.7 mg m-2, 임자도 갯벌 2.9~120.2 mg m-2, 여자만 갯벌 10.1~147.7 mg m-2, 4개 지역의 총 생물량 범위는 2.9~215.7 mg m-2였다. 엽록소 a의 분해 산물인 phaeopigment 농도로는 유부도 갯벌에서 1.7~470.8 mg m-2, 곰소만 갯벌에서 52.3~277.2 mg m-2, 임자도 갯벌에서 0.6~78.9 mg m-2, 여자만 갯벌에서 39.1~346.3 mg m-2으로 나타났다. 조사 대상지역의 종 다양성과 생물량은 높은 경향을 나타내었다. 한국의 남서해안은 다양한 저서돌말류가 서식하며 엽록소 a의 높은 농도는 일차생산력을 결정하는 주요인자다.

With land-use (cover) and water quality, the distributional characteristics of epilithic diatom communities were studied with 193 samples from estuaries of Korean peninsula between 2015 and 2016. Of total 394 taxa classified, Nitzschia perminuta (19.6%) and N. inconspicua (14.0%) were the 1st and 2nd dominant species. Using a cluster analysis, the epilithic diatom communities of Korean estuaries were divided into four groups (G1-G4). Ecological characteristics of each group were followed: G1 was located in estuaries of the East Sea, and characterized by high forest land-use and high DO and low nutrients; G2 was the eastern part of the South Sea, and characterized by low turbidity and nutrients; G3 was the western part of the South Sea, and characterized by high agriculture, low electric conductivity and low salinity; G4 was the Yellow Sea, and characterized by high nutrients. The environmental factors having significant correlation with diatom distributions were as follows: TN to G1, turbidity to G2, agriculture to G3, and TP to G4. Moreover, the important factors affecting the occurrence of indicator species were forest land-use for Fragilaria construens var. venter in G1, turbidity for Rhoicosphenia abbreviata in G2, urban land- use and total phosphorus (TP) for Bacillaria paradoxa and Hantzschia amphioxys of G3, and TP and turbidity for N. ovalis and Stephanodiscus invistatus of G4. These results collectively indicate that the distribution of epilithic diatom communities in Korean peninsula was largely effected by water quality and land cover/use.

This research was conducted to find the indigenous diatom species unrecorded in Korea from February to December 2016. The samples were taken at 28 sites of the coastal regions on the west coast of Korea and Jeju Island. Diatoms were collected mostly from sand and mud of tidal flats, including gravel, seaweed on the bottom and macrophytes floating in the seawater. Diatom specimens were observed by means of light and scanning electron microscopy. Twenty one species were discovered and added as new specimens to the Korean diatom flora, which are divided into 9 orders, 12 families, and 16 genera. The list and photographs of the species are included with the description of the morphological characteristics and distribution in Korea.

The aims of this study were to analyze the physico-chemical factors and the characteristics of epilithic diatom community from 15 sites of the Naeseongcheon and tributaries located in the upper region of the Nakdong river from May to October 2016. The biological water quality was assessed using DAIpo and TDI. A total of 163 diatom taxa were identified with 2 orders, 3 suborders, 9 families, 35 genera, 145 species, 16 varieties and 2 forms. Cocconeis placentula var. lineata appeared at every examined sites. Achnanthes lanceolata, Nitzschia fonticola, Nitzschia inconspicua and Reimeria sinuata were common taxa of the Naeseongcheon. Nitzschia inconspicua and Achnanthes minutissima were major dominant species. As a result of the CCA, Electrical conductivity and total nitrogen concentration were important factors determining the diatom species composition. In the result of the biological assessment using DAIpo, the Naeseongcheon was rated at class B with an average of 62.38. In the result of assessment using TDI, the Naeseongcheon was rated at class C with an average of 66.12.

This taxonomic study sought to detect and describe diatom species not yet recorded in Korea. The study was conducted at three islands located off the western coast of Korea, Wido Island near Buan, Wonsando Island near Boryeong and Dekjeokdo Island near Incheon. Diatoms were collected from the bottom, stone, macrophytes and other substrates in water bodies, which are affected by seawater. Fifteen naviculoid taxa are described. Of these, 13 are novel to Korea. The genus Navicula has nine species; Navicula alineae Lange-Bertalot, N. ammophila Grunow, N. cariocincta Lange-Bertalot, N. elegantoides Hustedt, N. longicephala Hustedt, N. normaloides Cholnoky, N. notha Wallace, N. novaesiberica Lange-Bertalot, N. riediana Lange-Bertalot & U. Rumrich. The genus Craticula has four species; Craticula buderi (Hustedt) Lange-Bertalot, C. halophila (Grunow) D.G. Mann, C. riparia (Hustedt) Lange-Bertalot and C. riparia var. mollenhaueri Lange-Bertalot.

This study illustrates changes in the epilithic diatom assemblages in response to urban climatic conditions. We further assess the impact of abnormal urban climate to the urban stream environment. Epilithic diatoms, water chemical and physical variables were sampled every quarter, and assessed at 3 Oncheon stream sites, for a period of two years (from 2013~2014). The variation of physiochemical properties such as BOD, COD, T-N and T-P, show that the water quality was strongly influenced with long periods of drought and flood disturbance. Epilithic diatom assemblages were separated along the stream sites; however, the physical disturbance from urban drought and stormwater changed the composition of diatom assemblages instead of decreasing the taxonomic richness. Thus, our results suggest that epilithic diatom assemblages are altered in response to urban climatic changes, resulting in variations of stream conditions. Hence, strategies of climate change adaptation are required when considering urban stream environments.