• Journal of Species Research
• /
• v.9 no.4
• /
• pp.427-442
• /
• 2020

We collected indigenous Korean ciliate species from diverse aquatic and terrestrial habitats in 2018 and 2019. The morphology of these ciliates was revealed based on the observations of living cells, and protargol-impregnated and/or silver carbonate-impregnated specimens. During this study, we found 16 previously unrecorded Korean ciliate species, which are as follows: 1) class Heterotrichea - Stentor introversus; 2) class Spirotrichea - Aspidisca orthopogon, Amphisiella sinica, Epiclintes auricularis rarisetus, Apokeronopsis wrighti, Pseudokeronopsis carnea, Trachelostyla pediculiformis, Strombidium apolatum, and Varistrombidium kielum; 3) class Phyllopharyngea - Chlamydodon obliquus, Dysteria aculeata, and Hartmannula angustipilosa; 4) class Litostomatea - Paraspathidium apofuscum; and 5) class Oligohymenophorea - Frontonia angusta solea, Metanophrys sinensis, and Uronemita binucleata. Here, we provide a diagnosis for each species with a brief remark. Among them, the infraciliature of the poorly known species, Stentor introversus and Dysteria aculeata, is described for the first time. Further, we revise the Korean population of Pseudokeronopsis pararubra, which was previously misidentified as Pseudokeronopsis carnea.

• Journal of Korean Society on Water Environment
• /
• v.29 no.6
• /
• pp.825-831
• /
• 2013

The Suwon stream which consists of a mountainous reach, an artificial reservoir and an urban reach provides benthic macroinvertebrates with various habitats. This study was conducted to find out the influence of reservoir sluice control and water quality on benthic macroinvertebrates community in the Suwon stream from June to August, 2011. As a result, substrate composition showed little difference between the upper site (S2) and the lower site of the reservoir (S3). At site S3, water velocity was fastest, and water temperature was lowest due to the intermediate depth discharge of the reservoir. Cheumatopsyche brevilineata which prefer fast water velocity was dominant at site S3. Some biotic indices (H', J, and R) of site S3 decreased significantly whereas Benthic Macroinvertebrate Index (BMI) showed little difference between site S2 and site S3. EPT showed a negative correlation with water temperature. The sluice control of the reservoir leaded variations of water velocity and temperature, and seemed to make the state of aquatic ecosystem worse.

• Korean Journal of Plant Taxonomy
• /
• v.47 no.3
• /
• pp.180-188
• /
• 2017

We evaluated the actual distribution, present status, and number of remnant individuals of Korean Sagittaria aginashi (Alismataceae) based on herbarium specimens and field surveys. We also reidentified Korean S. aginashi by analyzing sequences of the internal transcribed spacer (ITS) region. We found nine specimens of S. aginashi in herbaria from four localities housed at the Osaka Museum of Natural History (OSA) and at the Korea National Herbarium (KH). During our field research, we could not confirm the current statuses of two collection localities (Taereung and Ansan-si), though this was not the case for Ulsan-si. In addition, we found two new localities in Ulsan-si and Yangsan-si. These three remnant populations are distributed in wetlands in mountainous areas (elev. 480-740 m). With regard to the number of flowering and immature individuals in the three localities, there were <50 and <2,000, respectively, in total. ITS sequences demonstrated that the sequences of Korean and Japanese S. aginashi are uniform and distinct from other Sagittaria species. These results indicate that S. aginashi is a rare and threatened species in Korea. It should be listed as an endangered species on the Korean Red List and requires urgent protection by conservation programs, including the extensive surveys of other possible natural habitats.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.63 no.6
• /
• pp.89-100
• /
• 2021

The conservation of stream habitats has been gaining more public attention and fish habitat suitability index (HSI) is an important measure for ecological stream habitat assessment. The fish habitat preference is affected not only by physical stream conditions but also by water quality of which HSI was not available due to the lack of field data. The purpose of this study is to estimate the HSI of Zacco platypus for water quality parameters of water temperature, dissolved oxygen (DO), and biochemical oxygen demand (BOD) using the water environment monitoring data provided by the Ministry of Environment (ME). Fish population data merged with water quality were constructed by spatio-temporal matching of nationwide water quality monitoring data with bio-monitoring data of the ME. Two types of the HSI were calculated by the Instream Flow and Aquatic Systems Group (IFASG) method and probability distribution (Weibull) fitting for the four major river basins. Both the HSIs by the IFASG and Weibull fitting appeared to represent the overall distribution and magnitude of fish population and this can be used in stream fish habitat evaluation considering water quality.

• Environmental Engineering Research
• /
• v.23 no.4
• /
• pp.374-382
• /
• 2018

Petroleum hydrocarbons pollutants, such as diesel fuel, have caused ecosystem damage in terrestrial and aquatic habitats. They have been recognized as one of the most hazardous wastes. This study was designed to optimize the effect of Tween 80 concentration, nitrogen (N)/phosphorus (P) ratio and salinity level on diesel biodegradation by Vibrio alginolyticus (V. alginolyticus). Response surface methodology with Box-Behnken design was selected with three factors of Tween 80 concentration (0, 5, 10 mg/L), N/P ratio (5, 10, 15) and salinity level (15‰, 17.5‰, 20‰) as independent variables. The percentage of diesel degradation was a dependent variable for 14 d of the remediation period. The results showed that the percentages of diesel degradation generally increased with an increase in the amount of Tween 80 concentration, N/P ratio and salinity level, respectively. The optimization condition for diesel degradation by V. alginolyticus occurred at 9.33 mg/L of Tween 80, 9.04 of N/P ratio and 19.47‰ of salinity level, respectively, with percentages of diesel degradation at 98.20%. The statistical analyses of the experimental results and model predictions ($R^2=0.9936$) showed the reliability of the regression model and indicated that the addition of biostimulant can enhance the percentage of diesel biodegradation.

• Mycobiology
• /
• v.49 no.6
• /
• pp.559-581
• /
• 2021

The coastal marine ecosystems of Vietnam are one of the global biodiversity hotspots, but the biodiversity of marine fungi is not well known. To fill this major gap of knowledge, we assessed the genetic diversity (ITS sequence) of 75 fungal strains isolated from 11 surface coastal marine and deeper waters in Nha Trang Bay and Van Phong Bay using a culture-dependent approach and 5 OTUs (Operational Taxonomic Units) of fungi in three representative sampling sites using next-generation sequencing. The results from both approaches shared similar fungal taxonomy to the most abundant phylum (Ascomycota), genera (Candida and Aspergillus) and species (Candida blankii) but were different at less common taxa. Culturable fungal strains in this study belong to 3 phyla, 5 subdivisions, 7 classes, 12 orders, 17 families, 22 genera and at least 40 species, of which 29 species have been identified and several species are likely novel. Among identified species, 12 and 28 are new records in global and Vietnamese marine areas, respectively. The analysis of enzyme activity and the checklist of trophic mode and guild assignment provided valuable additional biological information and suggested the ecological function of planktonic fungi in the marine food web. This is the largest dataset of marine fungal biodiversity on morphology, phylogeny and enzyme activity in the tropical coastal ecosystems of Vietnam and Southeast Asia. Biogeographic aspects, ecological factors and human impact may structure mycoplankton communities in such aquatic habitats.

• The Plant Pathology Journal
• /
• v.40 no.3
• /
• pp.251-260
• /
• 2024

Flavobacterium is a genus within the phylum Bacteroidota that remains relatively unexplored. Recent analyses of plant microbiota have identified the phylum Bacteroidota as a major bacterial group in the plant rhizosphere. While Flavobacterium species within the phylum Bacteroidota have been recognized as pathogens in the aquatic habitats, microbiome analysis and the characterization of novel Flavobacterium species have indicated the great diversity and potential of their presence in various environments. Many Flavobacterium species have positively contribute to plant health and development, including growth promotion, disease control, and tolerance to abiotic stress. Despite the well-described beneficial interactions of the Flavobacterium species with plants, the molecular mechanisms and bacterial determinants underlying these interactions remain unclear. To broaden our understanding of the genus Flavobacterium's role in plant health, we review the recent studies focusing on their ecological niche, functional roles, and determinants in plant-beneficial interactions. Additionally, this review discusses putative mechanisms explaining the interactions between plants and Flavobacterium. We have also introduced the importance of future research on Flavobacterium spp. and its potential applications in agriculture.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.4
• /
• pp.527-536
• /
• 1996

The patterns of diel horizontal migration (DHM) of 7 copepod species are compared as part of a general investigation of the zooplankton adaptations to the surf zone habitats. In a sandy shore surf zone of Yongil Bay, 3 sites such as the bottom and surface of 1 m water depth and water's edge are sampled with a sledge net(n=108). The surf zone copepod assemblage is dominated by 7 species; Acartia hudsonica, Fseudodiaptomus marinus, Paracalanus indicus, Calanus sinicus, Oithona similis, Sinocalanus tenellus and Labidocera bipinnata. Threefold variations in copepod abundance are observed within a diel cycle. Abundances of 7 dominant species and total copepods captured in the surface exhibit significant diel differences, but those taken in the bottom are not significantly affected by diel period. It is shown that about $90\%$ of the surf zone copepods performed DHM. The nocturnal high densities of copepods occurred for a neap tide when the offshore winds prevailed, suggesting the animals' ability for horizontal orientation and an active locomotion without invoking passive transportation by currents. Photoreactive behavior of copepods triggered by relative changes in light intensity may be a primary factor inducing DHM by aggregating in the surf zone during the night and spreading out at day; then copepods may reduce encounters with visual predators. In A. hudsonica, ontogenetic variations in timings of DHM are evident. Such variations are likely to minimize intraspecific competition for diets. Data on shoreward migration of copepods indicate that A. hudsonica, P. indicus, O. similis and S. tenellus can maintain swimming velocities of about $20m\;h^{-1}$ for durations of more than an hour. Our observations of strong diel difference in abundances point out the need for both day and night samplings in surf zone habitats, if the importance of these habitats to planktonic copepods are to be fully understood.

• Ecology and Resilient Infrastructure
• /
• v.9 no.3
• /
• pp.194-205
• /
• 2022

Sandbars formed by sediment transportation and sedimentation are some of the most important habitats for specific wildlife and they provide an aesthetic landscape in streams. The purpose of this study was to understand the successional process of the colonization and development of early vegetation over time on sandbars exposed by the opening of a gate at a downstream weir. We selected the following four study sites in the Geumgang River, South Korea: three weir-upstream sites with different gate-opening times and a control site that was not affected by weir operation. Changes in the structural characteristics and spatial distribution of the riparian vegetation on the sandbars exposed after opening the gate at the weir were surveyed according to the different exposure periods of the sandbars at the study sites. The newly formed sandbars accounted for more than 33% of the area of the existing floodplain in the three weir-upstream sites of the Geumgang River after opening the gate at the weir. Nine main plant communities were distributed on the exposed sandbars. These communities were classified as annual mesophytic, perennial hydrophytic, perennial hygrophytic, subtree, and tree vegetation based on their species traits. As the duration of exposure of the sandbar increased, the area of the bare sandbar and the annual herbaceous and perennial hydrophytic communities decreased, and the areas occupied by perennial hygrophytic, subtree, and tree communities increased. Changes in vegetation on the sandbar were classified into three types of succession according to the condition of the aquatic habitat before the gate-opening and the degree of physical disturbance caused by the water flow after the gate-opening. The types of succession were: 1) succession starting from hydrophytes in the lentic aquatic zone, 2) succession starting from annual herbaceous hygrophytes in the lotic aquatic zone, and 3) willow-dominated succession in the disturbed channel side. Our results suggested that the dynamics of successional changes in vegetation should be considered during weir operation to ecologically manage the habitats and landscape of the fluvial landforms, including sandbars in streams.

• Korean Journal of Environmental Biology
• /
• v.38 no.1
• /
• pp.146-159
• /
• 2020

The objective of our study was to analyze the distribution and composition of fish species and their community characteristics in agricultural waterways in the six water systems-Mankyung River, Seomjin River, Namhae Region, Tamjin River, Yeongsan River, and Dongjin River-during 2017-2018. Little is known about the distributions and community characteristics of the aquatic biota of agricultural waterways in Korea, even if the water bodies have important roles as spawning areas or habitats for fish. In this study, we identified 3,633 fish individuals in the waterways, belonging to 53 species, eleven families, and six orders (dominant species: Tanakia koreensis, T. lanceolate) and 7,108 fish individuals in the main rivers, belonging to 57 species, fifteen families, and nine orders. Moreover, three endangered wildlife (designated by the Ministry of Environment, Korea)-T. somjinensis, Acheilognathus majusculus and Coreoperca kawamebari-were found in the waterways. By fish guild analysis, we found that many waterways had a lower proportion of sensitive species and a higher proportion of omnivore species than those of the main rivers, which indicates a feature of a disturbed environment. In addition, by grouping with environmental variables, we found the group of waterways with high substrate complexity had a higher diversity index (Shannon index) and a lower dominance index (Simpson index) than that of simple substrate complexity. Overall, our study represents the characteristics of fish habitats in agricultural waterways and suggests the need to manage them and study further.