• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.141-152
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• 2001

Abundance of autotrophic picoplankton (APP) and their contribution to phytoplankton biomass were assessed in seven brackish lagoons and five freshwater reservoirs in the summer season. Phycocyanin-rich picocyanobacteria dominated APP in lagoons, while phycoerythrin-rich picocyanobacteria dominated APP in freshwater reservoirs. The cell density of APP ranged from $3.6{\times}10^3$ to $5.0{\times}10^6\;cells/ml$ (median $2.5{\times}10^5$) in brackish lagoons and from $3.8{\times}10^4$ to $3.6{\times}10^5\;cells/ml$ (mdian $1.3{\times}10^5$) in reservoirs. Carbon biomass ranged from 1.0 to $1,385.0\;{\mu}gC/L$ in lagoons and from 15.3 to $128.2\;{\mu}gC/L$ in reservoirs. APP cell density in Lake Kyungpo was over $10^6\;cells/ml$in all three surveys, which is one of the highest values recorded in all over the world. During the thermal stratification in Lake Soyang, the maximum abundance of APP and their maximum contribution to phytoplankton biomass were observed near the thermocline. This study showed that APP sometimes can contribute significantly to phytoplankton biomass both in lagoons and reservoirs with the range from 0.1 to 85.0%. APP which have been overlooked in the past studies appears to be important primary producers in Korean lake ecosystem.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.76-86
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• 2012

Macrozoobenthos were collected from 24 sites using small grab ($0.05m^2$) in order to see the spatial distribution of them at Sueocheon stream at the northern part of Gwangyang Bay during summer season when the maximum ecological processes are occurring. A total of 44 species of macrozoobenthos occurred, and their mean density was $789individuals/m^2$. Mollusks was the dominant faunal group accounted for 43.1% and 86.8% of the whole community density and biomass, respectively. Top five dominant species were a molluscan, Corbicula japonica (40.7%), two polychaete worms, Neanthes japonica (19.3%) and Heteromastus filiformis( 8.1%), and two crustaceans, Paranthura japonica (6.9%) and Jaeropsis sp. (6.9%). Species diversity index was very low with mean value of 1.12 and maximum value was recorded at the river mouth. At the upper stream, a brackish water species such as Corbicula japonica showed their maximum population density. The overall distribution of stream macrobenthos showed a rather simple pattern along with salinity and grain size gradients with few brackish water species occurring at coarse sediments in the stream but more diverse faunas inhabiting fine sediments in the river mouth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.335-343
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• 2009

Antimicrobial resistance patterns of Vibrio species isolated from brackish water in Geoje, Tongyeong and Goseong, Gyeongsangnamdo province into which streams, sewage and leachate all flowed. Only 19 strains (10.7%) of 177 V. parahaemolyticus were susceptible to 15 antimicrobials. 146 strains (69.5%) proved resistant against more than one antimicrobial and 12 strains (6.8%) were multi-drug resistant. The resistance rate of 152 strains were 85.9% against AM and 26.6% against RA, 16.4% against AN, 13.6% against Sand 13.0% against TMP. 86 strains of 129 V. cholerae non-O1 (66.7%) were susceptible to antimicrobials and 31 strains (24.0%) were resistant to more than one antimicrobial and 12 strains (9.3%) were multi-drug resistant. The antimicrobial resistance rate of 129 strains against 15 antimicrobials, with the exception of C, CIP, E and GM, i.e. 11 antimicrobials, was 0.7-16.2%, 16.2% of 129 strains proved resistant against RA and 13.9% against AM, 9.3% against TMP, 7.7% against SXT and 6.9% against TE. 19 of 49 strains of V. mimicus (38.8%) were susceptible to antimicrobials and 31 strains (61.2%) were resistant against more than one antimicrobial; none of the strains were multi-drug resistant. 15 strains of V. mimicus were resistant against only RA, AmC and TE. The resistance rate was 59.2% against RA (highest) 4.1% against AmC and 2.0% against TE.

• The Korean Journal of Malacology
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• v.23 no.1
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• pp.39-49
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• 2007

We investigated to understand the differences in the karyotypes and the reproductive characteristics between the diploid clam, Corbicula japonica in the brackish water and the triploid clam, C. fluminea in the freshwater. The number of chromosomes of the diploid C. japonica were 38, which can be grouped into 19 pairs of two homologues. These can be divided into 11 pairs of telocentric, 4 pairs of subtelocentric, 3 pairs of submetacentric and one pair of metacentric chromosomes. C. japonica is oviparous and dioecious. The clam has two pairs of gills, with the inner and outer-demibranchs, however, they do not act mainly as marsupia. External fertilization occurs in the brackish water. The triploid marsh clam, C. fluminea has 54 chromosomes, which can be grouped into 18 sets of three homologues. These 18 sets can be divided into one metacentric group, five submetacentric groups and 12 subtelo- or telocentric groups. C. fluminea is ovoviviparous and functional hermaphrodite. The triploid condition may be closely related to hermaphroditism. This species has the inner-demibranchs acting mainly as marsupia. The depletion of ripe eggs occurred in the inner-demibranchs of the gill during the incubatory periods, and ripe eggs produced in the hermaphroditic follicles in the gonad during the non-incubatory periods. The gonad developmental stages of two marsh clams (C. japonica and C. fluminea) can be divided into five stages: early active stage, late active stage, ripe stage, partially spawned stages, and spent/inactive stage.

• Parasites, Hosts and Diseases
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• v.32 no.3
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• pp.163-170
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• 1994

An epidemiological survey was performed to know the infection status of heterophyid fluke metacercariae in the brackish water fishes purchased from a local market in Haenam-gun, Chollanam-do, Korea from November to December, 1991. A total 20 out of 30 shads (Konosiw punctatus) examined were infected with the metacercariae of H. continua (average number of larvae per an infected fish: 2.71). Of 20 perches (Lateolabroxjoponicurs), 19 were Infected with the metacercariae of H. continua (average number per an infected fish: 17.21. Of 30 mullets (Mugil cepholus) examined, 11 were Infected with the metacercariae of H. nocens (average number per an Infected fish: 51.5), 10 mullets harboured 31 and 349 metacercariae of f summa and 5. lucatum respectively. Of 30 gobies (Acnnthogobin jlcvimonus) examined, 3 were infEcted with the metacercariae of H. nucens (average number per an Infected fish: 32.0), 8 with those of H. continua (average number per an infected flesh: 12.6) and 3 with those of 5. JuscntuwL From the above results, It has been confirmed that the brackish water Ash from Haenam-gun, Chollanam-do are infected with numerous metacercarlae of H. nocens, H. continua, P. summo and S. fuscatum.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.566-572
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• 2017

For four times, zooplankton collection were conducted seasonally in October 2015-July 2016 at five sites located in the wet lands of the lower Han River, ie., Si-am, Sung-dong, Gong-reung stream, San-nam and Jang-hang. A total of 46 species of zooplankton were collected, which comprise 25 species of rotifers, seven cladocerans, ten copepods, and one species of nematod, ostracod and decapod, respectively. No brackish and marine species were distributed except for two species of brackish water copepods. Prosperity in the species number of 15 species was observed in October at Sung-dong and Jang-hang. The maximum abundance was recorded in March at Si-am with $8,000indiv.\;L^{-1}$ with the explosion of Brachionus calyciflorus. Other sites also showed high abundances in March with the abundance higher than $5,000indiv.\;L^{-1}$. Except in March, the abundance levels were recorded as less than some hundred $indiv.\;L^{-1}$ throughout the study. Species diversity varied between 0.4-1.8. The gut contents of the copepodite showed that various diatoms might be their major food items, and lots of unidentified materials were also observed. The environmental conditions of water temperature, pH and dissolved oxygen content showed to vary $10.1-28.2^{\circ}C$, 7.1-8.6 and $4.5-11.0mg\;L^{-1}$, respectively.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.72-81
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• 2019

Bisphenol A (BPA), a representative endocrine disrupting chemicals, has adverse effects on growth, development and reproduction in aquatic organisms. The object of this study was to investigate the modulation of antioxidant enzyme-coding genes using quantitative real time RT-PCR (qRT-PCR), enzyme activity and total protein content, to understand oxidative stress responses after exposure to BPA for 48 h in brackish water flea Diaphanosoma celebensis. The BPA ($3mg\;L^{-1}$) significantly upregulated the expression of Cu/Zn-SOD, Mn-SOD, and catalase (CAT) mRNA. Three GST isoforms (GST-kappa, GST-mu, and GST-theta) mRNA levels significantly increased at the rate of $0.12mg\;L^{-1}$ of BPA. In particular, GST-mu showed the highest expression level, indicating its key role in antioxidant response to BPA. SOD activity was induced with a concentration-dependent manner, and total protein contents was reduced. These findings indicate that BPA can induce oxidative stress in this species, and these antioxidants may be involved in cellular protection against BPA exposure. This study will provide a better understanding of molecular mode of action of BPA toxicity in aquatic organisms.

• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.255-266
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• 2022

In crustaceans, molting is regulated by interactions between ecdysteroid and juvenile hormone (JH) signaling pathway-related genes. Unlike the ecdysteroid signaling pathway, little information on the role of JH signaling pathway-related genes in molting is available in zooplanktonic crustaceans. In this study, three genes (juvenile hormone acid O-methyltransferase (JHAMT), methoprene-tolerant (Met), and juvenile hormone epoxide hydrolase (JHEH)) which are involved in the synthesis, receptor-binding, and degradation of JH were identified using sequence and phylogenetic analysis in the brackish water flea, Diaphanosoma celebensis. Transcriptional changes in these genes during the molting cycle in D. celebensis were analyzed. Sequence and phylogenetic analysis revealed that these putative proteins may be functionally conserved along with those of insects and other crustaceans. In addition, the expression of the three genes was correlated with the molting cycle of D. celebensis, indicating that these genes may be involved in the synthesis and degradation of JH, resulting in normal molting. This study will provide information for a better understanding of the role of JH signaling pathway-related genes during the molting process in Cladocera.

• 보존과학연구
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• s.7
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• pp.265-277
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• 1986

The degradation of wood is maimly caused by biological and thermal factor. In general, the field of wood preservation can be divided into two broadcategories; namely the deterioration, protection of wood, and the teatment of wood with preservatives. Wood in sea or brackish water incurs marine borer damage, consisting of attack by marine animal and also wood on land suffers severely from insect damage. But the largest wood degradation is caused by microorganism. Animals that attack wood in a marine environment are especially destructive in warm water-regions, little was achieved in their control recently. Therefore this manuscript only introduce the importance of wood deterioration caused by marine animal.

• 한국해양학회지
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• v.20 no.2
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• pp.61-66
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• 1985

A mysid, Neomysis awatschensis(Brandt), which distributes abundantly in brackish lakes, estuaries and salt marshes along the southern and western coast of Korea, from Kimhae to Inchon is described and recorded as new to Korea. The world distribution of the species are also revised with short discussion.