• Journal of Species Research
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• v.11 no.2
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• pp.79-88
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• 2022

The Ulvophyceae are a diverse group and most species are distributed in marine environments, however, a smaller diversity occurs in freshwater and terrestrial habitats. Also, the diversity of species belonging to Ulvophyceae has been superficially investigated in Korea. Here, we identify two freshwater ulvophycean species based on the morphology, ultrastructural observation, and phylogenetic analysis. As a result, their taxonomic classifications are as follows: order Ulvales Blackman and Tansley, 1902 - family Kornmanniaceae Golden and Cole, 1986 - Lithotrichon pulchrum Darienko and Proschold 2017; order Ulotrichales Borzi, 1895 - family Tupiellaceae Skaloud and Leliaert, 2018 - Tupiella speciosa Darienko and Proschold 2017. The family Tupiellaceae and the two genera Lithotrichon and Tupiella are reported for the first time in Korea.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.247-258
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• 2021

To understand restoration and conservation projects conducted in Korea for endangered freshwater fishes and amphibians/reptiles, information about Request for Protocols-related studies on restoration, breeding, and release were collected. Trends of studies were visualized via word clouds and VOSviewer program using a text mining technique. Analysis of restoration projects for endangered freshwater fishes elucidated that most research studies conducted to date were focused on genetics and release through captive breeding that could be classified into captive breeding and habitat environments. As for research projects related to amphibians/reptiles, monitoring projects had the highest number, followed by genetic, translocation, and monitoring studies. In addition, restoration projects for amphibians/reptiles included a large number of post-capture translocation projects. Thus, many projects were confirmed by public institutions rather than by the Ministry of Environment. Network analysis revealed that it was largely classified into capture, translocation, and Kaloula borealis. Based on these results, limitations, achievements, and challenges associated with projects conducted thus far are highlighted. Research directions for future restoration and conservation of endangered freshwater fishes and amphibians/reptiles in South Korea are also suggested.

• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.242-249
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• 2023

The aquarium pet trade is a source of potentially invasive crayfish species, which can be subsequently intentionally or unintentionally introduced into new environments. There were 34 species of freshwater crayfish imported into Korea for ornamental purposes. Starting with 1 species in 2008, it shows a trend of continuous increase every year with the maximum of 25 species in 2020. The number of freshwater crayfish imported into Korea for ornamental purposes was 1,172,159, with an annual average of 78,144 being imported. The population also recorded a record high in 2017 with a 38% increase in population imports compared to the previous year. Among the 34 pet crayfish imported into Korea, four species classified as high-risk and managed in the US and Europe were American crayfish (Procambarus clarkii), Cherax quadricarinatus, Cherax cainii, and Cherax destructor. In addition to American crayfish (P. clarkii), 3 types of high-risk invasive crayfish are designated as legally managed species by conducting an ecological risk assessment, raising awareness among importers, retailers and consumers through awareness-raising education on freshwater crayfish, and measures for route management such as species identification and improvement of labeling methods are needed.

• Journal of Species Research
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• v.13 no.3
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• pp.332-339
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• 2024

The filamentous freshwater red alga Compsopogon caeruleus(Compsopogonophyceae, Compsopogonaceae, Rhodophyta) occurs in tropical and subtropical regions of worldwide. This species has been reported from Asia, America, Africa, Europe and Oceania, and the worldwide distribution of Compsopogon caeruleus is in variable water habitats. Several morphospecies of the genus Compsopogon had been recorded, but recent molecular phylogenetic analyses with worldwide sampling identified a monospecific genus, C. caeruleus. In the present study, we first report a freshwater red alga Compsopogon caeruleus from Korea. We identified Compsopogon caeruleus in an urban river in Yongin City, and analyzed its morphological and genetic characteristics. Nuclear 18S rDNA, plastidal rbcL gene and mitochondrial cox1 gene sequences isolated from Korean Compsopogon caeruleus showed high sequences similarity with Compsopogon caeruleus from worldwide (98.6-100% (18S rDNA), 99-100% (rbcL) and 97.7-100% (cox1)). These sequences similarities support the identification of a red alga found in Korea as Compsopogon caeruleus. This new geographical report provides the useful information for understanding the distribution and habitat range of Compsopogon caeruleus especially concerning urban freshwater environments.

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.433-449
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• 2020

Nine fish and one clam species were collected from freshwater environments in Korea, including four lakes, two streams, and the Nakdong River, to investigate the host-associated bacteria. Hundreds of bacterial strains were isolated from the samples using a cell sorter and a dilution plating method. After identification of the bacterial strains using 16S rRNA gene sequences, 42 strains with greater than 98.7% sequence similarity with validly published species were determined to be unrecorded bacterial species in Korea. These strains were phylogenetically diverse and assigned to four phyla, six classes, 17 orders, 27 families, and 32 genera. At the genus level, the unrecorded species were classified as Corynebacterium, Mycobacterium, Mycolicibacterium, Gordonia, Williamsia, Modestobacter, Brachybacterium, Sanquibacter, Arthrobacter, and Mycolicibacterium of the class Actinobacteria; Empedobacter, and Flavobacterium of the class Flavobacteriia; Fictibacillus, Psychrobacillus, Cohnella, Paenibacillus, Rummeliibacillus, Enterococcus, and Vagococcus of the class Bacilli; Aquamicrobium, Paracoccus, and Sphingomonas of the class Alphaproteobacteria; Achromobacter, Delftia, and Deefgea of the class Betaproteobacteria; and Aeromonas, Providencia, Yersinia, Marinomonas, Acinetobacter, and Pseudomonas of the class Gammaproteobacteria. The 42 unrecorded species were subjected to further taxonomic characterization using gram staining, cellular and colony morphological determination, biochemical analyses, and phylogenetic analyses. This paper provides detailed descriptions of the 42 previously unrecorded bacterial species.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.825-833
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• 2017

Strain IMCC26207 was isolated from the surface layer of Lake Soyang in Korea by the dilutionto-extinction culturing method, using a liquid medium prepared with filtered and autoclaved lake water. The strain could neither be maintained in a synthetic medium other than natural freshwater medium nor grown on solid agar plates. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain IMCC26207 formed a distinct lineage in the order Acidimicrobiales of the phylum Actinobacteria. The closest relative among the previously identified bacterial taxa was "Candidatus Microthrix parvicella" with 16S rRNA gene sequence similarity of 91.7%. Here, the draft genome sequence of strain IMCC26207, a freshwater actinobacterium, is reported with the description of the genome properties and annotation summary. The draft genome consisted of 10 contigs with a total size of 3,316,799 bp and an average G+C content of 57.3%. The IMCC26207 genome was predicted to contain 2,975 protein-coding genes and 51 non-coding RNA genes, including 45 tRNA genes. Approximately 76.8% of the protein coding genes could be assigned with a specific function. Annotation of the IMCC26207 genome showed several traits of adaptation to living in oligotrophic freshwater environments, such as phosphorus-limited condition. Comparative genomic analysis revealed that the genome of strain IMCC26207 was distinct from that of "Candidatus Microthrix" strains; therefore, we propose the name "Candidatus Limnosphaera aquatica" for this bacterium.

• Parasites, Hosts and Diseases
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• v.55 no.1
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• pp.95-98
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• 2017

Fasciola hepatica is a trematode that causes zoonosis, mainly in cattle and sheep, and occasionally in humans. Few recent studies have determined the infection status of this fluke in Korea. In August 2015, we collected 402 samples of freshwater snails at Hoenggye-ri (upper stream) and Suha-ri (lower stream) of Song-cheon (stream) in Daegwalnyeong-myeon, Pyeongchang-gun in Gangwon-do (Province) near many large cattle or sheep farms. F. hepatica infection was determined using PCR on the nuclear ribosomal internal transcribed spacer 2 (ITS-2). Among the 402 samples, F. hepatica 1TS-2 marker was detected in 6 freshwater snails; thus, the overall prevalence in freshwater snails was 1.5%. The prevalence varied between collection areas, ranging from 0.0% at Hoenggye-ri to 2.9% at Suha-ri. However, F. gigantica ITS-2 was not detected in the 6 F. hepatica-positive samples by PCR. The nucleotide sequences of the 6 F. hepatica ITS-2 PCR-positive samples were 99.4% identical to the F. hepatica ITS-2 sequences in GenBank, whereas they were 98.4% similar to F. gigantica ITS-2 sequences. These results indicated that the prevalence of F. hepatica in snail intermediate hosts was 1.5% in Gangwon-do, Korea; however the prevalence varied between collection areas. These results may help us to understand F. hepatica infection status in natural environments.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.946-956
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• 2018

The gut microbiota of aquatic animals plays a crucial role in host health through nutrient acquisition and outcompetition of pathogens. In this study, on the basis of the high-throughput sequencing of 16S rRNA gene amplicons, we examined the bacterial communities in the gut of freshwater shrimp (Macrobrachium nipponense) and in their living environments (sediment and pond water) and analyzed the effects of abiotic and biotic factors on the shrimp gut bacterial communities. High bacterial heterogeneity was observed in the freshwater shrimp gut samples, and the result indicated that both the surrounding bacterial community and water quality factors (particularly dissolved oxygen and temperature) could affect the shrimp gut bacterial community. Despite the observed heterogeneity, 57 genera, constituting 38-99% of the total genera in each of the 40 shrimp gut samples, were identified as the main bacterial population in the gut of M. nipponense. In addition, a high diversity and abundance of lactic acid bacteria (26 genera), which could play significant roles in the digestion process in shrimp, were observed in the shrimp gut samples. Overall, this study provides insights into the gut bacterial communities of freshwater shrimp and basic information for shrimp farming regarding the application of probiotics and disease prevention.

• Korean Journal of Ecology and Environment
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• v.57 no.1
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• pp.51-59
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• 2024

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.

• Korean Journal of Environmental Biology
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• v.25 no.1
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• pp.27-33
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• 2007

Sediment microcosm experiments were conducted for 14 and 28 days using Zn spiked sediment to examine chronic toxicity (mortality) of Diporeia spp. as a function of density and time. Mean cumulative Diporeia mortality in 28 day sediment microcosms was 25% at $1,800\;{\mu}g\;g^{-1}$ total Zn in sediment. Although a certain fraction $(20{\sim}40%)$ of Diporeia was dead, its mortality was attributed by handling stress within 4 days and was not significantly encreased with increasing within the range of Zn concentrations examined in this study. These results suggest that Diporeia can tolerate Zn contaminated sediment and may be useful as a biomonitor for Zn contamination in freshwater environments.