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ISSN : 1225-3480
Growth and survival (%) of the larvae and spats of Scapharca broughtonii fed on three different microalgal species (Isochrysis galbana, Pavlova lutheri and Chaetoceros simplex) were investigated with the analysis of fatty acid composition. The larvae fed on mixed diet with three microalgal species showed the highest growth in shell length (<TEX>$261.3{\pm}13.5{\mu}m$</TEX>) and survival (<TEX>$27.4{\pm}5.3%$</TEX>). The growth and survival (%) of the larvae fed on the single diet with C. simplex were significantly higher than those of the larvae fed on I. galbana or P. lutheri (P < 0.05). The growth and survival (%) of S. broughtonii spats reared for 30 days were also highest in the mixed diet group with <TEX>$1,114.8{\pm}128.0{\mu}m$</TEX> and <TEX>$61.3{\pm}5.5%$</TEX>, respectively, and followed by C. simplex, I. galbana and P. lutheri. With respect to composition of fatty acid of the single or mixed microalgal diet, the content of PUFA and n-3 HUFA were the highest in C. simplex. This result can be considered as the reason for high growth and survival (%) of the larvae and the spats. C. simplex was the best species as the single diet, but the mixed diet with three microalgal species showed better dietary value than single diet did for the larvae and spat of S. broughtonii.
Manila clam, Ruditapes philippinarum (SL; <TEX>$32.74{\pm}2.18mm$</TEX>, TW; <TEX>$8.29{\pm}1.41g$</TEX>, N; 450) were exposed to various concentrations of naphthalene for 20 weeks. Exposure concentrations of naphthalene established control, solvent control (ethanol), 30, 60, 90 and <TEX>$120{\mu}g$</TEX> Nap <TEX>$L^{-1}$</TEX> following results of 96h acute exposure. After exposure during 20 weeks, survival rate of the manila clam was lowed in 60, 90 and <TEX>$120{\mu}g$</TEX> Nap <TEX>$L^{-1}$</TEX> exposure group compared control group. Also, sex ratio of male was higher in <TEX>$60{\mu}g$</TEX> Nap <TEX>$L^{-1}$</TEX> exposure group (<TEX>${\chi}^2=5.492$</TEX>, P < 0.05) but lowed <TEX>$90{\mu}g$</TEX> Nap <TEX>$L^{-1}$</TEX> exposure group (<TEX>${\chi}^2=4.214$</TEX>, P < 0.05) and <TEX>$120{\mu}g$</TEX> Nap <TEX>$L^{-1}$</TEX> exposure group (<TEX>${\chi}^2=30.118$</TEX>, P < 0.05). Gonad development was delayed in female (> <TEX>$60{\mu}g$</TEX> Nap <TEX>$L^{-1}$</TEX>) and male (> <TEX>$30{\mu}g$</TEX> Nap <TEX>$L^{-1}$</TEX>). Intersex was 16.28% in female, 1.68% in male. In this result, naphthalene caused survival decrease, imbalance of sex ratio, delay of gonad development of the manila clam. Also, chronic exposure to naphthalene suggested abnormal effects in reproduction of the manila clam.
Mass production method on artificial seedling production of hard clam Meretrix petechialis was developed indoor culture system. Spawning of adult clam (SL <TEX>$65.8{\pm}8.4mm$</TEX>) was induced using the combined method of air exposure and water temperature raising. The fertilized eggs were developed to D-shaped larvae after 17.7 hours at <TEX>$27^{\circ}C$</TEX> and hatching rate was 6.1%. Shell length (SL) of D-shaped larvae was measured to be <TEX>$131.4{\pm}2.6{\mu}m$</TEX> and thereafter the larvae grew to the settled spats with SL <TEX>$190.2{\pm}7.5{\mu}m$</TEX> in 4 days. Estimated survival rate of settled spats was 48.1%. Spat collection on 130,000 spats with SL <TEX>$0.19{\pm}0.01mm$</TEX> performed conducted by sand bottom circulation filtering method. Collected spats grew up to <TEX>$3.1{\pm}0.8mm$</TEX> in 46 days, <TEX>$6.6{\pm}1.8mm$</TEX> in 87 days, and <TEX>$10.5{\pm}0.9mm$</TEX> in 114 days. The relative growth between SL and shell height (SH) was calculated to be SH = 0.8501SL + 0.0196 (<TEX>$R^2=0.9987$</TEX>) during the whole spat period. During spats rearing, they were suffered from one time of mass mortality at SL 3.1 mm, but 51,000 spats were finally survived with the rate of 39.2% at 114 days of spat rearing in indoor tank system.
Light and transmission electron microscopy of Batillus cornutus hemocytes revealed differences that the morphological distinctions between blast-like cell, granulocytes and hyalinocytes. Base on the morphological characteristics of the cells, we identified the eight types of hemocytes and present a categorization of the hyalinocytes into six sub-categories. The hemocytes of B. cornutus were observed basophilic cell under the light microscopy. Blast-like cells had a spherical profile with a central nucleus filling almost the whole cell. Granulocytes were characterized by presenting variable numbers of granules. This cell had spherical shape with diameter 7 <TEX>${\mu}m$</TEX> and smooth endoplasmic reticula, granules, mitochondria, glycogen granules in the cytoplasm. Hyalinocytes were the most abundant cell type. Especially, hyalinocyte VI had iirregular an amoebal shape and observed autophagosome and heterophagosome in the cytoplasm. From these results, it is concluded that there are eight types of cells in the hemolymph of B. cornutus. Further studies are now needed to identify the role of these hemocytes in the enzymological and immunological response.
The Korean muricid snails are listed include previous record and three unrecorded species, Morula iostoma, Coralliophila morishimai, and C. abnormis collected from Mudo of Jeju-do were redescribed. As a result, the family Muricidae in Korea turned out to be 44 species of 22 genera.
This study was conducted to estimation the selection response for growth-related traits in 31-month old of Pacific abalone, Haliotis discus hannai were born in 2008. In overall mean of surveyed traits and standard deviation showed <TEX>$76.31{\pm}7.247$</TEX> mm of shell length, <TEX>$49.48{\pm}5.307$</TEX> mm of shell width and <TEX>$40.96{\pm}6.80$</TEX> g of total weight. The effect of sex and maturity were statistically significant in all traits include out a condition factor (p < 0.01). And In effect of sex, female were higher than male in all traits excepting condition factor, significantly. In correlation between breeding value and phenotypic value by each traits, showed rank correlation coefficient and simple correlation coefficient, which represented low positive correlation. A hopeful genetic improvement to the next generation showed 6.96 mm of shell length, 4.47 mm of shel width and 12.93 g of total weight. Therefor, It is considered that if considering properly selection intensity and selection ratio, efficient improvement could be made.
The growth rates of offspring of selected abalone (SA), Haliotis discus hannai, population for rapid growth were compared to those of offsping of the control abalone (CA) at bred under the same condition. The growth traits (shell length, shell breadth and total weight) of SA were significantly faster than those of CA at this experiment. At the 45th day and 90th day, the growth rates in shell length of SA were estimated 31.7% and 17.8% faster than those of CA, total weight of SA were estimated 43.7% and 25.6%, respectively. Moreover, the relative growth rate between shell length and total weight of SA showed significant differences higher than one in CA at 90th day. The results suggest a possibility of improving the growth rate of cultured abalone using selection techniques.
The purpose of this study is to compare the clearance rate (CR) and intake rate (IR) of juvenile purple clam, Saxidomus purpuratus when feeding on different unialgal diet of red tide dinoflagellates (RTDs), and to know what is the most important cell characteristic of RTDs to cause the differences in feeding parameters. Experiments were performed to measure the CR and IR of juvenile S. purpuratus as a function of algal concentration when food was either the standard food, Isochrysis galbana or one of 9 RTDs. Patterns of CR with increasing algal concentration were similar among different RTDs. The highest <TEX>$C_{max}$</TEX> was observed when S. purpuratus was feeding on A. affine, while the lowest on C. polykrikoides. The patterns of IR with increasing algal concentration were also similar among different RTDs. However, there were great differences in the maximum value of IR (<TEX>$I_{max}$</TEX>) among different RTDs. The highest <TEX>$I_{max}$</TEX> was observed when S. purpuratus was feeding on A. carterae, while the lowest on G. catenatum. Some RTDs similar in size showed different <TEX>$C_{max}$</TEX>. Other RTDs different in size showed similar <TEX>$I_{max}$</TEX>. Life form of each RTD affected significantly the <TEX>$I_{max}$</TEX>, which was higher for single-celled RTDs than chain-forming RTDs. There were no significant differences in feeding parameters between toxic and nontoxic RTDs. Moreover, a toxic dinoflagellate, A. carterae recorded the highest <TEX>$I_{max}$</TEX> among RTDs. The most important characteristic of RTD as a factor affecting the feeding rate of S. purpuratus was life form, not size or toxicity of RTD species.
The specimens of bursid snail, Bursa (Bursa) bufonia (Gmelin, 1791) were collected from Jeju Island, Korea and diagnostic characters were analysed. This is the first report of the family Bursidae and the genus Bursa in the Korean waters.
The gametogenic cycle, the number of spawning seasons per year and first sexual maturiity of the pen shell, Atrina (Servatrina) pectinata, were investigated by quantitative statistical analysis using an Image Analyzer System. Compared two previous results (the spawning periods in the reproductive cycles in 1998 and 2006) by qualitative histological analysis with the present results by quantitative statistical analysis, there are some differences in the spawning periods: the spawning period (June to September) by quantitative statistical analysis was one month longer than those of two previous reports (June to July or June to August) by qualitative histological analysis. However, the number of spawning seasons studied by the qualitative and quatitative analyses occurred once per year. In quantitative statistical analysis using an image analyzer system, the patterns of monthly changes in the percent (%) of the areas occupied by follicles to the ovary area in females (or that of the areas occupied by spermatogenic stages to the testis area in males) showed a maximum in May, and then sharply droped from June to September, 2006. From these data, it is apparent that the spawning season of A. (S.) pectinata occurred once a year from June to September, indicating a unimodal gametogenic cycle during the year. Shell heights of sexually mature pen shells (size at 50% of group sexual maturity, <TEX>$GM_{50}$</TEX>) that were fitted to an exponential equation were 15.81 cm in females and 15.72 cm in males (considered to be one year old).
The importance of biological resources has been gradually increasing, and mollusks have been utilized as main fishery resources in terrestrial ecosystems. But little is known about genomic and transcriptional analysis in mollusks. This is the first report on the transcriptomic profile of Meretrix lusoria. In this study, we constructed cDNA library and determined 542 of distinct EST sequences composed of 284 singletons and 95 contigs. At first, we identified 180 of EST sequences that have significant hits on protein sequences of the exclusive Mollusks database through BLASTX program and 343 of EST sequences that have significant hits on NCBI NR database. We also found that 211 of putative sequences through local BLAST (blastx, E < e-10) search against KOG database were classified into 16 functional categories. Some kinds of immune response related genes encoding allograft inflammatory factor 1 (AIF-1), B-cell translocation gene 1 (BTG1), C-type lectin A, thioester-containing protein and 26S proteasome regulatory complex were identified. To determine phylogenetic relationship, we identified partial sequences of four genes (COX1, COX2, 12S rRNA and NADH dehydrogenase) that significantly matched with the mitochondrial genomes of 3 species-Ml (Meretrix lusoria), Mp (Meretrix petechialis) and Mm (Meretrix meretrix). As a result, we found that there was a little bit of a difference between sequences of Korean isolates and other known isolates. This study will be useful to develop breeding technology and might also be helpful to establish a classification system.
