• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.173-178
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• 1980

Cercaria larvae of Bacciger harengulae which is parasitic to Meretrix lusoria, rapes japonica and Solen strictus were studied in terms of their morphology and incidence of infection rate. The host bivalves were collected from Naechodo, Okgu-gun during the Period from January to November in 1980. The tail of the cercaria bears 27 pairs of tufts of setae, the tufts being composed of 6 fine rays. Oral sucker, intestine, ventral sucker and a pair of testes are distinctive. The excretory duct bears numerous granules of various size, and the flame-cell arrangement is represented by a formula 2[(3+3)+(3+3)]=24. The cercaria is somewhat similar to the previously known Cercaria pectinata . It is however conformed that present cercaria belongs to Bacciger harengulae. Infection rate showed seasonal variation and host selectivity. Higher infections were observed in Solen strictus, and lower in Meretrix lusoria. Generally, the larger bivalves over 2-3 years old showed the higher infection rate.

• Journal of Environmental Health Sciences
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• v.27 no.4
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• pp.25-34
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• 2001

Heavy metal level and distribution in sediment and bivalves from the tidal flats along the mid-western coast, Korea. were investigated in this study. The averages of heavy metal concentrations in sediments from 5 sampling sites ranged from 86.35-187.77mg/kg for Mn. 13.25-17.73mg/kg for Zn.6.80-11.85mg/kg for Cr,4.28-6.25mg/kg for Ni, 1.85-3.09mg/kg for Cu, 0.004-0.02()mg/kg for Cd and 5.70-10.41 mg/kg for Pb, respectively. From the results of heavy metal concentrations in mussels, the levels of Mn and Fe concentrations in S. strictus collected from S1 antral S2 sites were particularly high. Deviations of heavy metal concentrations am(Ing the individual mussels from the same site could be largely minimized by selecting mussel samples of the limited range in body size(8.5-11cm). Among the mussels of the limited body size, heavy metal concentrations both in the flesh and in the whole soft part were not strongly related to the body size. It was shown that ,in S. strictus, Cu moves fast into the flesh parts after absorption, while Pb and Fe move fast into the non-flesh parts. Overally. the heavy metal concentration in the tends to increase with that in the whole soft parts. The concentration factors(heavy metal concentration in 5. strictus/heavy metal concentration in sediment) showed that, of the examined meta1s. Cd is the most cumulative in the body of S. strictus followed by Zn and Cu, while Mn, Cr. Ni and Pb are not cumulative.

• Journal of Korean Society on Water Environment
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• v.18 no.4
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• pp.341-354
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• 2002

Heavy metal concentration/distribution in sediments and bivalves from the tidal flats in Saemankeum coastal area, western Korea, were investigated, Among 6 sampling sites, S2, S5 and S6 showed the higher levels of Zn, Cr, Ni, Cu and Cd contamination and S1 did the higher level of Pb contamination than other sites, while S-4 showed the lowest levels of these metal contamination. Overally, the levels of Zn, Cu and Pb concentrations in Sinonovacula constricta were estimated to be relatively high. The shell lengths of the collected mussels were linearly related to their dry weights of the whole soft parts, but the mussels collected from S3 were in a poor nutrition, resulting in the distinctively high levels of metal concentrations in the body. It was shown that in S. constricta, Cr, Ni, Cu and Zn are distributed equally into the whole soft parts or a little more into the flesh, after absorption, while Fe, Cd, Pb and Mn are transferred more into the non-flesh parts than into the flesh parts. In S. constricta, the heavy metal concentrations in the flesh increase with those in the whole soft parts. The bioaccumulation factors(heavy metal concentration in S. constricta/heavy metal concentration in sediment) showed that, of the examined metals, Cd is the most cumulative in the body of S. constricta, followed by Zn and Cu, while Mn, Cr, Ni and Pb are not cumulative.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.546-549
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• 2000

For the establishment of biodetoxification method which can be acceptable for live bivalves, paralytic shellfish poison (PSP) detoxification bacteria were isolated from sea water and bivalves, and PSP detoxification activity and optimal growth condition of the isolated strains were investigated. from the bivalve and sea water samples, 8 strains of PSP detoxification bacteria were isolated. Of the isolated strains, CW-6 isolated from sea water shown strong PSP detoxification activity and decomposed completely 18 nmole/g of GTX2 after 3 days incubation in artificial medium. The selected stain CW-6 shown typical characteristics of the Enterobacter sp. and identified as Enterobacter sp, CW-6. Optimal growth condition of the Enterobacter sp. CW-6 were $35^{\circ}C$, pH 7 and $NaCl 1{\%}$, respectively.

• Korean Journal of Ecology and Environment
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• v.51 no.3
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• pp.245-252
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• 2018

Stable isotope tracers were first applied to evaluate the Microcystis cell assimilation efficiency of bivalves, since the past identification method has been limited to tracking the changes of each chl-a, clearity, and nutrient. The filter-feeders (Sinanodonta woodiana and Unio douglasiae) were assessed under the condition of cyanobacteria (Microcystis aeruginosa) blooms through an in mesocosm experiment using $^{13}C$ and $^{15}N$ dual isotope tracers. chl-a concentration in the treatment mesocosm was dramatically decreased after the beginning of the second day, ranging from 116 to $66{\mu}g\;L^{-1}$. In addition, the incorporated $^{13}C$ and $^{15}N$ atom % in the S. woodiana bivalve showed higher values than U. douglasiae bivalves. The results demonstrate that U. douglasiae has less capacity to assimilate toxic cyanobacteria derived from diet. Our results therefore also indicate that S. woodiana can eliminate the toxin more rapidly than U. douglasiae, having a larger detoxification capacity.

• The Korean Journal of Malacology
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• v.27 no.1
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• pp.9-14
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• 2011

This study was examined digestive enzyme activity in the crystalline style of the three species of bivalves. Bivalves used in this study were Tegillarca granosa (n=61), Mytilus galloprovincialis (n=30) and Saxidomus purpuratus (n=30) and collected from southern coast of Korea on May 2010. Digestive enzymes activities in the crystalline style were assayed in spectrophotometer. Amylase and cellulase occupied approximately 90% of digestive enzyme in crystalline style of T. granosa, M. galloprovincialis, and S. purpuratus. And protease activity in crystalline style of T. granosa, M. galloprovincialis and S. purpuratus showed the lowest values to 0.02, 0 and 0.08%, respectively. Digestive enzyme activity in crystalline style of three species was measured in the order of cellulase > amylase > chitinase > laminarinase.

• The Korean Journal of Malacology
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• v.22 no.2
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• pp.167-173
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• 2006

The embryos of marine bivalves have been commonly used in bioassays for quality assessments of marine environments. Although several standard protocols for the developmental bioassay of bivalves have been proposed, only a few trials for application of these protocols in environmental assessments or for the development of a new protocol with Korean species have been conducted. As such, there is a strong need to establish standard bioassay protocols with bivalves commonly found in Korean waters. To determine the sensitivity of Mytilus galloprovincialis to establish a standard bioassay, their fertilized eggs were exposed to six metals (Ag, Cd, Cr, Cu, Ni, and Zn). The order of biological impact was Ag > Cu > Ni > Zn > Cr > Cd and their lowest observed effective concentration were 5, 16.4, 25.4, 142, 187 and 1,500${\mu}g/l$, respectively. The proportion of normal larvae appeared to decrease linearly with the logarithm of each toxicant concentration within the tested range. The average values of median effective concentrations $(EC_{50})$ from the triplicate experiments for Ag, Cd, Cr, Cu, Ni, and Zn were 6.8, 1,797, 786, 16.6, 68.1, and 139.2${\mu}g/l$, respectively. There was a more than 100-fold difference in $EC_{50}$ values of Cu and Cd. The value of $EC_{50}$ or median lethal concentration of Cu was within the range observed for other bivalve developmental bioassays. The overall sensitivity of M. galloprovincialis in the present developmental bioassay was also similar to that of other marine organisms commonly used in aquatic bioassays (e.g. sea urchins, oysters). Hence, the bioassay using the embryo of M. galloprovincialis is considered to be a useful tool to monitor and evaluate the quality of marine aquatic environments.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.4
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• pp.328-335
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• 2023

In this paper, among the various facilities used in marine farming, young bivalves of the Mytilus galloprovincialis of marine farming was placed on the deck of the fishing vessel to evaluate the environment conditions and drive shaft movement by rolling affecting the separator for the young bivalves and a clean process. There were a few studies on stress analysis of development facilities because it was difficult to access the fishing site due to the use of imported equipment and the lack of development of domestic equipment. In this study, stress analysis of the fixed part of separator for young bivalves and its adjacent part was performed on various phases when the vessel was tilted by rolling using the finite element method. In addition, the structural safety of the internal blade under the driving conditions according to the movement of the drive shaft by the hydraulic motor was confirmed through structural analysis. As a result, the connection part between the deck and the separator by rolling was confirmed to have higher stress than that of other parts due to stress concentration. In addition, it was confirmed that the maximum stress occurred on the connection part between blades. Even though the safety of the separator for marine farming was confirmed by structural analysis, it is necessary to comprehensively consider the age of vessels, the material of the deck, and the corrosion of the deck.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.4
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• pp.227-231
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• 1978

Effects of suspended silt and clay on the survival of the rearing bivalves, Meretrix lusoria, Cyclina sinensis and Mactra veneriformis were studied. During sixty-five days of experimental cultures in different concentrations of suspended silt and clay and in different time of immersions, mortalities of the bivalves were checked every day, and the rates of shell movement and oxygen consumption were measured. In general, the higher the concentration of silt and clay and the longer the immersion time, the earlier the occurence, and the higher the rate of the mortalities of the experimental bivalves. M. veneriformis was subjected to earlier mortality than the others, and the period of $50\%$ mortality was the shortest of the three species (37 days in 1,000 ppm), and longer was that of C. sinensis(42 days). Mortality of M. lusoria occured latest and $50\%$ mortality was seen at the immersion time of 50-51 days. Particularly, M. lusoria showed no mortality in the sea water with 100 ppm of suspended silt and clay, and even in the concentrations of 500 or 1,000 ppm they were able to survive without mortality only if the immersion time was short (12-18 hours per day). M. veneriformis and C. sinensis were also able to survive without mortality when the immersion time was short (12 hours per day) in low concentration (100 ppm). Shell movements of experimental bivalves varied depending upon species. In the case of M. veneriformis the shell was opened continuously and C. sinensis opened their shells frequently, while M. lusoria maintained their shells closed in any experimental concentrations of sea water with suspended silt and clay. Total metabolic activity of M. veneriformis was found to be highest while that of M. lusoria showed the lowest. Little difference of oxygen consumption in excised gill tissue was shown between the control group and the experimental groups. Consequently, it may be stated that the mortality results from a immersion in sea water with high concentration of suspended silt and clay for long-time although the survival rates of the experimental bivalves depend also upon the species, physiological conditions, concentration of suspended silt and clay and immersion time. The survival percentage of bivalve y in relation to the time (day) of immersion X in sea water of suspended silt and clay was found to be: $$M.\;lusoria\;(1,000\;ppm):\;y=7.7\times10^9\;\chi^{-4.77}\;(500\;ppm):\;y=259\chi^{-0.26}$$ $$C.\;sinensis\;(1,000\;ppm):\;y=-21\chi+936\;(\chi<44),\;y=-0.65\;\chi+35\;(\chi>44)$$ $$(500\;ppm):\;y=4.4\times10^5\;\chi^{-2.27}$$ $$M.\;veneriformis\;(1,000\;ppm):\;y=-18\chi+716\;(\chi<39),\;y=-0.89\chi+39\;(\chi>39)$$

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.1-9
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• 2014

Lake Suwa is a natural lake which is well-known for sightseeing and fisheries. It had suffered severe eutrophication during 1960s and 1970s with the occurrence of cyanobacterial blooms and the extinction of some benthic animals. Since 1980 water quality has been improved due to efforts of local government, scientists, and citizens. Of various methods that were attempted to improve the water quality of Lake Suwa biological methods received much attention, because it can improve the lake ecosystem integrity and fisheries in addition to the water quality. The aim of this paper is to introduce the biological methods for water quality improvement that had been employed in Lake Suwa, Japan, and their contribution to the economic benefit of local residents. Until now a significant restoration of water quality has been achieved, but there are insufficient recovery of the sediment and biota due to anoxic hypolimnion of the lake. This study proposed suspended cage culture of bivalves as a feasible method of water quality improvement. Increased grazing by bivalves will contribute to the improvement of water quality and fisheries production, which will contribute both to the ecological restoration and economy of local residents.