This note summarizes the application of zooplankton indices for water quality management and estimation based on main research topics of articles focusing on wetland ecosystems, topics that are remained poorly investigated in S. Korea. The aquatic ecosystem-based consists of indices that respond to different target environmental factors, including environmental disturbance. Among the major indicator species and biota, we reviewed that management strategy for the wetland environment has to be focused more on small-sizes, in terms of zooplankton ecology and indices. The ecology of zooplankton communities in freshwater ecosystem has been the focus of an increasing number of studies since 2019, and considerable progress has been made in understanding the major mechanisms involved in regulating their abundance, diversity and spatio-temporal patterns. Even though studies on the freshwater ecosystem in Korea have a long history, a few of studies on zooplankton biota were conducted at wetlands. We suggested the candidate zooplankton indices proposed by the U.S. EPA and EU to suit Korean conditions. In the step of selecting metrics, the best available metrics are species-related variables, such as composition and abundance, as well as richness and diversity. Overall, in spite of several limitations, the development of a plankton-based multivariate assessment method in Korea wetlands is possible using mostly field research data. Later, it could be improved based on qualitative metrics on zooplankton, and with the emergence of further survey data. The present information can be used as basic information for researchers who are dealing with aquatic environments and its interaction with organisms.

본 연구에서는 남극 로스해 연안에 서식하는 아델리펭귄(Pygoscelis adeliae)과 황제펭귄 (Aptenodytes forsteri)의 분변 시료를 기반으로 펭귄 장내 미생물 메타지놈 연구를 수행하였 다. Taxonomy 분석 결과, 아델리펭귄과 황제펭귄의 장내 미생물에는 주로 7개의 문(phylum), 18개의 과(family)가 존재하는 것으로 나타났다. 또한 미생물 다양성을 평가하기 위해 Alpha diversity 및 OTU abundance 분석을 수행한 결과, 전반적으로 아델리펭귄의 장내 미생물 다양 성이 황제펭귄보다 높은 것을 확인하였고, PCoA를 기반으로 한 Beta diversity 분석을 통해 두 개체군 간 장내 미생물 군집에 차이가 존재함을 확인하였다. PICRUSt를 활용한 기능적인 차원의 KEGG pathway 분석을 통해서는 아델리펭귄과 황제펭귄 시료에서 nucleoside and nucleotide biosynthesis pathway가 가장 많이 존재하는 것을 확인하였다. 본 연구를 통해 남극 아델리펭귄과 황제펭귄의 장내미생물 구성과 다양성을 비교분석 할 수 있었다. 본 연구 결과 는 향후 펭귄의 먹이 섭식 관련 연구에 활용될 수 있으며, 더 나아가 다양한 남극 생물의 장내 미생물 메타지놈 분석에 대한 기초가 될 수 있을 것이다.

This study compares the abundance and community structure of zooplankton organisms from pelagic regions, and considers particularly the trophic levels vs. zooplankton abundances and biomass. Zooplankton samples were collected three times from May to November 2022, at 30 temperate lakes and reservoirs, which belong to four different river basins. The total zooplankton abundance, biomass and species index were showed considerable spatial variation. The spatial pattern of rotifer abundance was similar to that of total zooplankton abundance, while there were not showed similar patterns of zooplankton biomass (μg L-1) in lentic ecosystems. The rotifer strongly dominated the zooplankton assemblage in smaller lentic system than that of larger. A total of 130 species of zooplankton were identified (83 rotifers, 34 cladocerans and 13 copepods). The total average of zooplankton abundance and biomass were 213.7±342.3 Ind. L-1 (n=129) and 1382.8±1850.4 μg L-1, respectively. Total and average of zooplankton abundance were usually dominated by the rotifers (>56.9%), while those of zooplankton biomass were dominated by the cladocerans and copepods (>73.6%) in lentic ecosystems. Considering the Trophic State Index (TSI), the factors of zooplankton abundance and biomass were included in between meso- and eutrophic states (27 lakes, 90% of all). The mean abundance and biomass of zooplankton in eutrophic systems were higher than that of meso- and hypertrophic systems. From this result, we suggest that management strategy for the lentic ecosystem water environment has to be focused more on small-sized lakes and reservoirs, in terms of zooplankton assemblages.

The research was based on long-term studies on the major physico-chemical and hydrological factors and zooplankton community dynamics in the Hwang River. We had 341 times survey and collected zooplankton samples in the Hwang River of mid-Nakdong River from 1995 to 2013. We identified 97 zooplankton species, including 77 rotifers, 16 cladocerans, and 4 copepods. The total zooplankton abundance and species diversity were shown distinctive temporal variation (ANOVA, p<0.001). Annual average of zooplankton population density was 58.4±3.2 ind L-1 (n=341) and the lowest was 17.0±3.8 ind L-1 (1996, n=20), while the highest was 151.5±32.3 ind L-1 (2010, n=22). For zooplankton, small rotifer groups (e.g., Keratella sp., Brachionus sp., Trichotria sp.) dominated the study site for 19 years survey. Statistical analysis revealed that there were positive relationships with SiO2 (p=0.002) and water level (p<0.001) for the high abundance of rotifer community. There were considerable variations both the total cladocerans population and the number of cladocerans’ species concerning annual precipitation. Despite the appearance of various zooplankton in the Hwang River, the mean population density remained low. Due to the lateral structures in the Nakdong River, the downstream basin of the Hwang River is inevitably affected. The zooplankton community in our study site is considered to be mainly influenced by external factors that can stably increase and maintain the volume of the water body and internal factors that induce an increase in food sources through the inflow of nutrients into the water body.

Mitochondrial genomes of three specimens of Gadus chalcogrammus Pallas 1,814 from Korea and Japan were completely analyzed by the primer walking method. They were 16,570~16,571 bp in length, each comprising 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. Their gene orders were identical to those of conspecific specimens, but exhibited unique haplotypes. In the phylogenetic tree, the juvenile Korean and adult Japanese specimens were separated from the dominant clade composed of specimens from Japan, Korea, the Bering Sea, and the Arctic, including the adult Korean specimen.

The time series data of rotifer community focusing on the species number and total density were collected from 29 reservoirs located at Jeonnam Province from 2008 to 2016 quarterly. The reservoirs had similar weather condition during the study period, but their sizes and water qualities were different. To analyze the temporal dynamics of rotifer community, the medians, ranges, outliers and coefficient of variation (CV) value of rotifer species number and abundance were compared. For the temporal trend analysis, time series of each reservoir data were compared and clustered using the dynamic time warping function of the R package “dtwclust”. Small-sized reservoirs showed higher variability in rotifer abundance with more frequent outliers than large-sized reservoirs. On the other hand, apparent pattern was not observed for the rotifer species number. For the temporal pattern of rotifer density, COD, phytoplankton abundance fluctuation, and cladoceran abundance fluctuation have been suggested as potential factor affecting the rotifer abundance dynamics.

Gas springs applied to various industrial fields are generally composed of a cylinder, a piston rod, a cover, and a seal mount. Because of the thin wall of the cylinder, small gas springs are manufactured using a roller forming process that presses the cylinder wall into a groove of cover in the cylinder. In this study, finite element analysis and process design of roller forming are performed to systematically manufacture the small gas spring and develop a roller forming machine. In order to perform roller forming analysis, tensile tests of structural steel pipe are performed and mechanical properties are analyzed. Roller forming process parameters such as radius and depth of roller grooves are derived using the incompressible condition of plastic deformation theory and the results of finite element roller forming analysis. Using the derived roller shape, a roller forming machine is developed and prototypes of the small gas spring are manufactured. Finally, the dimensional accuracy of the manufactured gas spring prototypes is analyzed through three-dimensional shape measurement.

본 연구에서는 가리맛조개 (S. constricta)의 토사물을 현미경 검경과 차세대염기서열분석 (NGS) 기법으로 먹이원을 확인하고, 이를 통해 형태학적 및 분자학적 방법에 따른 먹이원 분석을 비교하였다. 가리맛조개 (S. constricta)의 먹이원은 분석방법에 따라 차이를 보였다. 먹이원생물은 위 내에서 분해되어 현미경 분석을 통한 생활사 확인과 정량적 분석이 가능하였으나 형태학적 및 해부학적 특성 파악이 불완전하였다. NGS 분석은 유기물 형태로 잔존하는 생물의 DNA 확인이 가능하여 현미경 검경 결과와의 상호보완적 적용 가능성을 확인하였다.

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.

본 연구에서는 영산강, 섬진강 유역에서 호소 간의 동물 플랑크톤의 군집구조 특성이 만수면적에 따라 분류된 소· 중·대형의 저수지에서 종 수 및 개체수가 유의한 차이를 보이는 것을 확인하였다. 윤충류보다 지각류에서 민감도가 높은 것을 확인하였으며, 특히 두 분류군 모두 양의 상관 관계를 나타냈지만, 지각류에서 조사지점이 늘어날수록 개체수 증가가 확연한 것을 알 수 있었다. 또한 네트워크 분석 개념을 활용한 고유벡터 중심성 및 그룹화 분석을 사용 하여 호소 간의 동물플랑크톤 군집구조를 비교했을 때, 만수면적에 따른 대·중·소형 호소 내에서도 지리적 특성과 미소환경 공간의 차이점을 구별할 수 있었다. 따라서 이러한 특성을 볼 때, 네트워크 분석은 담수 동물플랑크톤 군집구조 분석에 있어 만수면적 크기, 지리적 특성, 미소환경 특성을 반영할 수 있는 것으로 고려된다. 마지막으로, 네트워크 분석은 다양한 군집분석을 간소화하며 시각화를 통한 직관적 이해를 돕는 데 유용할 것이다.