• Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.43-50
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• 2005

We evaluated the nutritional composition of the siphon of the surf clam Tresus keenae in regard to the presence of nitrogenous [amino acids, nucleotides and their related compounds, total creatinine, betaine, trimethylamine oxide (TMAO), and trimethylamine (TMA)] and non­nitrogenous compounds (sugars and organic acids), lipid fatty-acid composition, and occurrence of minerals. The content of total free amino acids was 660.27 $\pm$ 7.94 mg/100 g, and the predominant amino acids were arginine, alanine, sarcosine, glycine, and glutamic acid. These amino acids accounted for $71\;\%$ of the total free amino acids. Among the nucleotides and their related compounds, inosine was the major component and comprised 40.38 $\pm$ 0.02 mg/100 g. Free amino acids were the largest contributor to total extracted nitrogen, comprising $49.94\%$, followed by total creatinine, betaine, nucleotides, and ammonia; the contribution of TMAO and TMA was small. For the non-nitrogenous compounds, malic acid, propionic acid, and succinic acid comprised the major portion of the ten kinds of organic acids detected, and the sugars found were glucose, maltose, and arabinose, which were estimated to be $147.0\pm7.15,\;34.45\pm1.09,\;and\;1.21\pm0.02\;mg/100\;g,$ respectively. The predominant minerals were Na and K, which comprised $11.43\pm1.06\;and\;9.46\pm1.02\;mg/100\;g,$ respectively. The major fatty acids were C22:6, C20:5, C23:0, C18:3, and C16:0 in the lipid fractions. The 23:0 level of glycolipid (GL) was the highest of any other lipid fraction. The amount of total polyunsaturated fatty acids (PUFA) in the lipid fractions was higher, ranging from $58.22\%\;in\;GL\;to\;77.1\%$ in phospholipid (PL), compared to the saturated and monounsaturated fatty acids. Of the n-3 fatty acids, C20:5 and C22:6 contributed $35.30-64.44\%$ of PUFA in the lipid fractions. The ratios of n-3 to n-6 PUFA in total lipid (TL), neutral lipid (NL), PL, and GL were 4.35, 4.26, 6.69, and 2.04, respectively.

• The Korean Journal of Malacology
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• v.26 no.4
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• pp.303-310
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• 2010

Rearing condition and species of microalgae on growth and survival of the sunray surf clam, Mactra chinensis larvae were investigated for artificial seedling production. The larvae of M. chinensis on higher temperature showed high growth and low survival and was grown over $230{\mu}m$ in shell length 14 days after hatching, but low growth as $151.1{\mu}m$ at $18^{\circ}C$. The larvae of M. chinensis on salinity showed highest daily growth and survival as $11.3{\mu}m$ and 65.8% at 30 psu, respectively. The optimum of water temperature and salinity for the larval rearing were $23^{\circ}C$ and 30-35 psu over 25 psu at least. The density of larval rearing was below 10 per 1 ml in rearing seawater for elevating the development rate from D-shaped to settled (metamorphosing) stage. The larvae fed the mixed diet of Isochrysis galbana, Pavlova lutheri, Isochrysis sp. (green), Chlorella ellipsoidea showed highest growth and survival. The larvae fed the single diet of I. galbana, Isochrysis sp. (green) showed high growth and survival. But the larvae fed the single diet of P. lutheri and C. ellipsoidea showed low growth and survival. The optimum diet of larvae of M. chinensis was over two species of microalgae included I. galbana, Isochrysis sp. (green) for elevating the high growth and survival.

• Environmental Mutagens and Carcinogens
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• v.15 no.2
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• pp.115-121
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• 1995

Bacterial mutagenicity of shellfish or canned products of red-muscle fish affected by hot-airdry processings and/or during storages was investigated by Ames preincubation method. Mussel (Mytilus edulis) and surf clam (Tapes japonica) dried under either 40$\circ$C, 50$\circ$C or 60$\circ$C until remained about 25 % water content was stored at 4$\circ$C or 25$\circ$C for 6 months. Commercially available canned product of pacific saury (Cololabis saira) and mackerel saury (Scotnberjaponicus), whose producer or date of manufacture was identical each other, was stored at 25$\circ$C for 6 months. Mutagenic substances from sample (25 g dry weight) were extracted and purified for mutagenicity assay against S. typhitnurium TA98 by the simultaneous distillation extraction (SDE) method (Lee et al. 1955). Mutagenicity of sample was expressed number of revertant per 25 g dry sample. Number of revertant from unheated mussel sample was appeared to be 135, relative to 22 from unheated surf clam sample. Mutagenicity of both shellfish was strongly affected by heat treatment, but a lesser extent by storage conditions, even at 25$\circ$C for 6 months. Revertants of the mussel sample dried at 40$\circ$C, 50$\circ$C, or 60$\circ$C was found to be 227, 779, and 883, respectively. Similar, but lower, mutagenicity was observed from the sample of surf clam dried at 40$\circ$C, 50$\circ$C, or 60$\circ$C than mussel. Mutagenicity of canned pacific saury and mackerel samples was not influenced by storage conditions. Number of revertant from pacific saury was 175 which was relatively higher than 5 from mackerel. Mutagenicity of fresh pacific saury and mackerel samples was significantly higher than that of their counterparts from canned products. These results indicate that mutagenicity of the shellfish was affected by heat treatment (40$\circ$C, 50$\circ$C, or 60$\circ$C) used for drying process, but not much by storage for 6 months at 4$\circ$C or 25$\circ$C and the mutagenicity of canned products of red-muscle fish was not influenced by storage, even at 25$\circ$C for 6 months.

• The Korean Journal of Malacology
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• v.13 no.2
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• pp.193-201
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• 1997

1990년 3월부터 1991년 2월까지 전라북도 군산 연안에 서식하는 동죽을 채집하여, 순간성장율, 순간사망율, 평균 생체량, 연간 생물생산력에 대하여 조사하였다. 치패는 각장 약 0.75 mm가 7월에 처음 채집되었으며, 0-5세의 6개 cohort로 구분되었다. 순간성장률은 여름철에 ？고 겨울철에 낮았지만, 순간사망률은 여름철에 높았다. 조사지역에서 동쪽 개체군의 연간평균 생체량은 3.865 g/$m^2$이었으며, 연간생산량은 3.933 g/$m^2$이었고, 연간 회전율은 1.020, 회전시간은 0.986년으로 추정되었다.

• Journal of Aquaculture
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• v.15 no.1
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• pp.39-42
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• 2002

Water temperature, at which Spisula sachdinensis egg successfully completed development ranges from 10 to $25^{\circ}C$. Within this range, the development duration is reduced with increasing temperature. The relationships between temperature (WT, $^{\circ}C$) and the required time (t: hour) from egg to each developmental stage are described as follows: 2-cell : 1/t = 0.0554 WT -0.3769; 8-cell : 1/t = 0.0210 WT -0.1142; Morula : 1/t = 0.0125WT -0.0712; Trochophore : 1/t = 0.0039 WT -0.0203; D-shaped larva : 1/t = 0.0024W T -0.0108. Biological minimum temperature for the egg development is 5.5$^{\circ}C$.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.67-73
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• 2018

This study was conducted to investigate the influence of environmental factors such as water temperature, salinity, rearing density and feeding amount on the survival and development of larvae in surf clam, Tresus keenae. As a result of this study, the optimum conditions of larval rearing were as follows. The optimum range of water temperature is 20℃ to 24℃, the optimum salinity is 30 psu, the optimum rearing density is 5 ind./ml and the supply of mixed feed organism for larva rearing such as Isochrysis galbana, Chaetoceros simplex and Tetraselmis suecica is 10×10⁴ cells/ml. The results of this study suggest that the optimum conditions of environmental factors in larval rearing of Tresus keenae contribute to productivity improvement through rapid growth and high survival.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.109-114
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• 2008

To evaluate the extent of Sea-Nine 211 (4,5-dichloro-2-n-octyl-3(2H) isothiazolone), one of the alternating organic booster compound used in antifouling paint to replace TBT, on marine benthic bivalve, we injected Sea-Nine 211 to clam, Pseudocardium sachalinensis, and then determined some xenobiotics metabolizing enzyme activities, especially EROD (ethoxyresorufin deethylase) and MROD (methoxyresorufin demethylase), in digestive gland during 4 day-exposure period. Moreover, the results were compared with those of TBT exposed clam. CYP1A1 dependant EROD activity in both the Sea-Nine 211 and the TBTC exposure groups showed no significant differences compared to those of the solvent control group. CYP1A2 dependant MROD activity in Sea-Nine 211 exposure group was significantly induced, but no significant difference was obtained in the TBTC exposure group. These results indicate that Sea-Nine 211 demonstrated a tendency to induce MROD activity, while TBTC inhibits the activities of this enzyme.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.1
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• pp.114-118
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• 1997

Effect of water temperature, salt and $MgCl_2$ concentration on sand ejection characteristics of short neck clam, Luditapes philippinarum was investigated. Unlike other shell fish such as red shell, arkshell and surf clam, treatment of short neck clam with sea water was evaluated not effective as sand ejection conditions. Sand ejection activity of short neck clam was shown effective at $2.5\%$ NaCl (pH 8.0) at $25^{\circ}C$. This activity was enhanced about 1.57 times when 50 mM $MgCl_2$ were added to the above mentioned conditions. But the extent of sand ejection activity was shown higher in the order of sea water $(3.2\%\;salt)+20mM\;MgCl_2$, sea water $(3.2\%\;salt),\;2.5\%\;NaCl+50mM\;MgCl_2$, treatments. Therefore, it was suggested that habitat conditions and Mg ions could be responsible for biological activity and concominant sand ejection of short neck clam.

• The Korean Journal of Malacology
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• v.4 no.1
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• pp.30-41
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• 1988

The gonadal development, the annual reproductive cycle and the first sexual maturity of surf clam, Mactra veneriformis Reeve were studied histologically. Speciemens were monthly collected at the intertidal zone of Naechodo, Chollabuk-do, Korea, for one year from March 1986 to February 1987. Sexuality of the clam is dioecious. The gonads were located between the subregion of mid-intestinal gland in the visceral cavity and the reticular connetive tissues of the foot, The ovary is composed of a number of ovarian sacs, and the testis comprise several testiculat lobules. The undifferentiated mesenchymal tissues and eosinophilic granular cells function as nutritive cells in the early stage. The ripe eggs were about 50-60${\mu}{\textrm}{m}$ in diameter, and they were wurroundedby the gelatinous membranes. The spawing period was from early June to September the main spawning occurred beetween July and August when the water temperature reached above 24$^{\circ}C$. The annual reproductive cycle of this species could be classified into five successive stages: multiplicative(January to March), growing(March to May), mature(April to August), spent(June to September), degenerative and resting(September to February). The monthly changes of fatness coefficient closely correlated with the annual reproductive cycle. Percentages of the first sexual maturity of female and male clams were over 50% among those individals ranging from 2.1 To 2.5cm, and 100% in those over 2.6cm in shell length.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1130-1133
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• 2002

Domoic acid, and amnesic shellfish poison, is a neurotoxin frequently found in shellfishes. Guidance level for the consumable shellfish has been established as $20\;{\mu}g$ domoic acid/g by Health and Welfare Canada and U.S. FDA. Domoic acid is produced by pennate diatom, a Nitzschia pungens f. multiseries ingested by the shellfish. Content of domoic acid in shellfish samples collected along the Korean shoreline from May to December of 1999 was analyzed. The collection included 1 Gastropoda (Murex shell) and 11 Bivalvias (oyster, little neck clam, orient hard clam, venus clam, surf clam, ark shell, hard-shelled mussel, pen shell, jack-knife clam, pink butterfly shell, and granulated ark shell). Samples were homogenized, extracted with 50% methanol, filtered, and analyzed by reversed-phase liquid chromatography at 242 nm with mobile phase consisting of 10% acetonitrile and 0.1% trifluoroacetic acid. Recovery of the HPLC analysis was 95.80% (${\pm}1.09$). All tested samples showed no domoic acid at the detection limit of 50 ng/g.