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Parasitism of the protozoan Perkinsus atlanticus in Manila clams, Ruditapes philippinarum, in Gomso Bay (Korea) and Ariake Bay (Japan)

  • Park, Kyung-Il;Choi, Kwang-Sik;Ngo, Thao T.T.;Tsutsumi, Hiro;Hong, Jae-Sang
    • Proceedings of the Korean Aquaculture Society Conference
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    • pp.513-513
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    • 2004
  • Manila clam, Ruditapes philippinarum, is commercially and ecologically important marine bivalve in Korea and japan. However, clam landings in the two countries have dramatically declined since the 1980-1990's. In the present study, the protozoan parasite, Perkinsus sp., lectin (host's defense-related glycoprotein) and histopathological features were investigated in Manila clams collected from Gomso Bay in Korea and Ariake Bay in japan (one of the largest clam beds in each country) during summer and fall, 2002-2003. DNA sequences of non-transcribe spacer (NTS), internal transcribed space. (ITS) and 5.85 rRNA of Perkinsus sp. were identical to those of P. atlanticus that was reported in Europe and Korea. For diagnosis of Perkinsus, the fluid thioglycollate medium (FTM) and the 2 M NaOH lysis methods were used. Prevalence of the parasite varied from 92.5-98.7% in Gomso Bay and 35.5-37.9% in Ariake Bay. Infection intensity, in terms of the number of Perkinsuscells per gram tissue wet weight, in the clams of Gomso Bay in fall 2002 averaged 1,010,077-470,937 recording approximately100 times higher than that of Ariake Bay, and these were twice higher than those of summer samples in each location. Mean hemagglutination titer of the clams from Gomso Bay was approximately 60-folds higher than that of clams from Ariake Bay in 2002. In histological preparation of the clams from Gomso Bay in 2002, trophozoites of P. atlanticus were in groups and resulted in severe inflammatory response of host clam. Prevalence of the trematod, Cercaria tapes-like in the clams of Gomso Bay and Ariake Bay were 8.8 % and 10.5% respectively. In conclusion, the clams from Gomso Bay showed more severe pathologic symptoms and higher immune response than those of the clams from Ariake Bay.

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Antimicrobial Resistance and Virulence Genes Presence in Escherichia coli Strains Isolated from Gomso Bay, Korea

  • Park, Kwon-Sam
    • Fisheries and aquatic sciences
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    • v.16 no.4
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    • pp.221-227
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    • 2013
  • In total, 131 Escherichia coli isolates from surface seawater of the Gomso Bay, of Korea, were analyzed for their susceptibility to 22 different antimicrobials and for genes associated with antimicrobial resistance and virulence. According to the disk diffusion susceptibility test, the resistance to tetracycline was most prevalent (33.6%), followed by that to ampicillin (22.1%), ticarcillin (22.1%), and trimethoprim (16.8%). More than 46.6% of the isolates were resistant to at least one antimicrobial, and 22.9% were resistant to three or more classes of antimicrobials; these were consequently defined as multidrug resistant. We further found that 29 ampicillin-resistant isolates possessed genes encoding TEM-type (93.1%) and SHV-type (6.9%) ${\beta}$-lactamases. Among the 44 tetracycline-resistant isolates, tetA and tetC were found in 35 (79.5%) and 19 (43.2%), respectively, whereas tetB was detected in only three isolates (6.8%). With regard to virulence genes, merely 0.8% (n = 1) and 2.3% (n = 3) of the isolates were positive for the enteroaggregative E. coli-associated plasmid (pCVD432) gene and the enteropathogenic E. coli-specific attaching and effacing (eae) gene, respectively. Overall, these results not only provide novel insight into the necessity for seawater sanitation in Gomso Bay, but they help reduce the risk of contamination of antimicrobial-resistant bacteria.

Distributions of Organic Matter and Trace Metals in Surface Sediments around a Manila Clam Ruditapes phillippinarum Farming Area in Gomso Bay, Korea (곰소만 바지락(Ruditapes phillippinarum) 양식장 주변 퇴적물 내 유기물과 미량금속 분포특성)

  • Choi, Minkyu;Lee, In-Seok;Kim, Chung-Sook;Kim, Hyung-Chul;Hwang, Dong-Woon
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.48 no.4
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    • pp.555-563
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    • 2015
  • Organic matter and trace metals were investigated in surface sediments of Gomso Bay, where there is dense Manila clam Ruditapes philippinarum farming activity, to evaluate contamination of sediments in intertidal shellfish farming area. We measured mean grain size (Mz), chemical oxygen demand (COD), ignition loss (IL), acid volatile sulfide (AVS), total organic carbon (TOC), and total nitrogen (TN), and trace metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb and Zn) in intertidal and sublittoral sediments. The intertidal sediments were mainly composed of coarser sediments (sand, silty sand, and sandy silt), with Mz values ranging from 2.61 to 4.79 Ø. Mz and the content of organic matter in sediments were lower in the intertidal zone than in the sublittoral zone. The mean metal concentrations in surface sediments decreased in the order Fe > Mn > Zn > Cr > Pb > Cu > As > Cd > Hg. The metal concentrations in surface sediments showed a significant positive correlation with Mz and organic matter content, indicating that metal concentrations in the surface sediments of Gomso Bay are controlled by Mz and organic matter. The concentrations of organic matter and trace metals in the study region were lower than or similar to those in other intertidal zones in western coast and much lower than those reported in other shellfish farming areas in Korea. Our results suggest that intertidal Manila clam farming sediments from Gomso Bay are not contaminated by organic matter and trace metals.

Resting Eggs of Copepods in the Intertidal Sediments of Gomso Bay, the West Coast of Korea

  • Jo, Soo-Gun
    • Journal of the korean society of oceanography
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    • v.37 no.3
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    • pp.108-115
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    • 2002
  • To Investigate the distribution of resting eggs at the intertidal zone, Gomso Bay, samples were taken from the top of the sediments to 10 cm depth at four sites using a cylindrical corer in February, 1997. Additional samples were also taken from one station at subtidal zone to compare the distributions between the inter- and subtidal zones. The resting eggs of few copepods, Acartia pacifica, Centropages abdominalis, Calanopia thompsoni, and Tortanus forcipatus were studied. Mostly, the abundance of the resting eggs in the lower intertidal zone was greater than that in the upper intertidal zone, but was not significantly different from that in the subtidal zone. The abundance of the resting eggs in the intertidal sediments was related with the grain-size and moisture content of sediments. Intertidal sediments are potential egg banks like subtidal sediments.

Geochemical Characteristics of Surface Sediments and an Evaluation of Trace Metal Pollution in Gomso Bay, Korea, 2011 (2011년 곰소만 표층퇴적물의 지화학적 특성 및 중금속 오염도 평가)

  • Kim, Chung-sook;Kim, Hyung Chul;Lee, Won Chan;Hong, Sokjin;Hwang, Dong-Woon;Cho, Yoon-Sik;Kim, Jin ho;Kim, Sunyoung
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.50 no.5
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    • pp.567-575
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    • 2017
  • To understand the geochemical characteristics of Gomso Bay, which features extensive Manila clam, we measured various geochemical parameters, organic matter, and trace metals (Cu, Cd, Pb, Zn, Cr, Hg, As and Fe) of intertidal and subtidal surface sediments in 2011. The surface sediments consisted of sedimentary facies including gravel (0.21%), sand (61.1%), silt (32.1%), and clay (6.5%). The chemical oxygen demand (COD) and acid volatile sulfide (AVS) values in most areas were below sediment quality criteria (COD, $20mg/g{\cdot}dry$; AVS, $0.2mg/g{\cdot}dry$). Trace metals in the surface sediments were below pollution thresholds, except for As (morderately polluted). Sediment quality was evaluated using the trace metal pollution load index (PLI) and ecological risk index (ERI), which showed that sediments were generally not polluted and at low risk; however, values along the outer bay were higher. We expect these results will be valuable for sustainable aquaculture prodution and environmental management in Gomso Bay.

Mass Balance Using the LOICZ Model in Gomso and Geunso Bays (LOICZ 모델을 이용한 곰소만, 근소만 갯벌어장 물질수지 산정)

  • Choi, Yong-Hyeon;Cho, Yoon-Sik;Choi, Yoon-Seok;Jeon, Seung Ryul
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.23 no.7
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    • pp.869-877
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    • 2017
  • Recently, Gomso Bay saw a decrease in the production of manila clam, which accounted for 17.8 % of production across the whole country in 2015, while Geunso Bay saw an increase that raised its contribution to 49.1 %. The tidal flats in these bays are inhabited by various benthos, and material flows in and out according to the tide. It is essential to understand the mass balance of these regions while giving consideration to the characteristics of these tidal flats. In this study, we compared areas where aquaculture farms were located in Gomso Bay with those without from May to August 2015. We divided the region into three sea areas (Sector I, Sector II, and Control), and the mass balance was estimated using the LOICZ model. As a result, the DIP of Sector II in Gomso Bay and another region in Geunso Bay, where a manila clam farm was located, were found to be -207.2 kg/day and 77.2 kg/day. The DIN was -4,996.7 kg/day and 926.6 kg/day. These results suggest that Gomso Bay han a higher density than Geunso Bay, which is thought to be mainly due to the feeding action of organisms. Therefore, in order to maintain a healthy tidal flat ecosystem and to sustain the production of manila clams, sustainable management to reduce the high density of tidal flat farms is necessary.

Antimicrobial Resistance and the Presence of Virulence Genes in Escherichia coli Strains Isolated from Ruditapes philippinarum in Gomso Bay, Korea (곰소만 해역의 바지락(Ruditapes philippinarum)에서 분리한 대장균 (Escherichia coli)의 항균제 내성 및 병원성 유전자의 보유성)

  • Kim, Tae-Ok;Eom, In-Seon;Park, Kwang-Ho;Park, Kwon-Sam
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.49 no.6
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    • pp.800-806
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    • 2016
  • In total, 151 Escherichia coli isolates from Ruditapes philippinarum in Gomso Bay were analyzed for their susceptibility to 18 different antimicrobial agents and for genes associated with virulence. For virulence genes, each strain of the isolates was positive for the enterotoxigenic E. coli (ETEC)-specific heat-stable toxin (estA), enteroinvasive E. coli (EIEC)-specific invasion-associated locus (iaa) gene and enteropathogenic E. coli (EPEC)-specific attaching and effacing (eae) gene. According to a disk diffusion susceptibility test, resistance to ampicillin was most prevalent (23.2%), followed by resistance to amoxicillin (22.5%), ticarcillin (20.5%), tetracycline (18.5%), nalidixic acid (12.6%), ciprofloxacin (10.6%), streptomycin (9.9%), and chloramphenicol (6.6%). More than 35.8% of the isolates were resistant to at least one antimicrobial agent, and 19.9% were resistant to four or more classes of antimicrobials; these were consequently defined as multidrug resistant. Minimum inhibitory concentration (MIC) ranges for the antimicrobial resistance of the 15 different antimicrobial agents of 54 E. coli strains were confirmed by varying the concentrations from $32-2,048{\mu}g/mL$. Overall, these results not only provide novel insights into the necessity for seawater and R. philippinarum sanitation in Gomso Bay but they also help to reduce the risk of contamination by antimicrobial-resistant bacteria.

Distribution of Pathogenic Vibrio Species in Seawater in Gomso Bay and Byeonsan, West Coast of Korea (곰소만 및 변산 해역 해수에 병원성 비브리오균(Vibrios spp.)의 분포)

  • Cho, Eui-Dong;Park, Kwon-Sam
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.52 no.6
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    • pp.625-630
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    • 2019
  • The pathogenic Vibrio genus contains halophilic bacteria that are distributed in marine and freshwater environments. Vibrio cholerae, Vibrio vulnificus, and Vibrio parahaemolyticus are potent human pathogens and leading causes of septicemia, wound infection, and seafood-borne gastroenteritis. The aim of this study was to investigate the presence of pathogenic Vibrio species in seawater off the west coast of Korea. Sixty-four seawater samples were obtained from different sites in Gomso Bay and Byeonsan from April 2018 to November 2018. Pathogenic Vibrio species were detected using a combination of most probable number (MPN)-polymerase chain reaction methods. V. cholerae, V. vulnificus, and V. parahaemolyticus were found in 0.0%, 20.3%, and 65.6% of seawater samples, respectively. Quantitative results revealed 3.6-23 MPN/100 mL of V. vulnificus, and 3.6-930 MPN/100 mL of V. parahaemolyticus in the samples. Overall, these results provide new insight into the necessity for seawater sanitation in Gomso Bay and Byunsan; they also provide evidence that will help reduce outbreaks of seafood-borne illness caused by pathogenic Vibrio species.

Tidal Flats and Resident Life : The Case of Bay, Gomso Bay, Youngwang Tidal Flat (서해안 갯벌과 주민 생활 -가로림만, 곰소만, 영광 갯벌을 사례로-)

  • Lee, Yun-Hwa
    • Journal of the Korean association of regional geographers
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    • v.12 no.3
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    • pp.339-351
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    • 2006
  • The purpose of this study is to investigate and analyze the relationships between tidal cycles, surface landforms, and sediments of tidal flats and their resident life. The study areas are Uengdo Ri in the Garolim Bay with wide the mud flat, Doou Ri in the Youngwang tidal flat which is developed sand flat and salt field, and Gomso Bay which is developed aquaculture industry. For resident around tidal flats, sea working takes precedence over farming, and main earnings gets from tidal flats. Resident life around the tidal flats is deeply related to tidal cycles, and low water level of spring tide becomes, they are most active and get more earnings than usual day, so it seems to be periodic markets. It is usually developed shellfish aquafarms in the mud flat, the stow net fishery in the sand flat, and salt fields in the mixed flat near the coast. Also a tidal flat has specialization of economic activity, and is divided into salt field and fish-farming in the supratidal zone, shellfish aquafarm in the intertidal zone, and oyster and porphyra culture in the subtidal zone.

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