• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.685-690
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• 2021

Harmful shell-boring species of the genus Polydora (Polychaeta: Spionidae) were frequently reported from commercially important mollusk species in Korea, Japan and China. The traditional approach based on the morphological characteristics showed limitations for species discrimination among shell-boring species. Therefore, DNA barcoding was adopted to identify Polydora species using molecular markers. Two Polydora species (P. haswelli and P. hoplura) in abalone shells were reported from our previous molecular phylogenetic study. In this study, we additionally reported the presence of shell-boring Polydora haswelli in commercially sold shellfish. The taxon-specific cox1 marker used in this study successfully allowed the isolation of P. haswelli from cockle Scapharca subcrenata, mussel Mytilus galloprovincialis, oyster Crassostrea gigas and scallop Argopecten irradians. Polydora hoplura was not found in these shellfish species. The genetic variations were found on the intraspecific level of P. haswelli and the same genotype was also detected in different shellfish species. This result can provide information on a new host and accurate parasitic Polydora species. Moreover, this report can be used as the biodiversity data of Polydora species on the invasion and transition of harmful Polydora species in mollusk aquaculture farms.

• The Korean Journal of Malacology
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• v.24 no.2
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• pp.121-130
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• 2008

In other aquaculture species, large improvements in growth have been achieved through selective breeding. Ezo abalone(Haliotis discus hannai) and disk abalone(H. discus discus) are major aquatic animals cultured in Asia, but selective breeding for the promotion of growth with these abalones has not been actively pursued. Recently significant efforts are being made to promote production of these species through selective breeding in Korea. The aims of this work were to estimate the general genetic parameters, heritabilities, and genetic and phenotypic correlations on growth-related traits at 1-year old in two Korean abalone subspecies, H. discus hannai and H. discus discus, by using multiple trait animal model. The data were collected from the records of 1,504 individuals produced from 22 sires and 26 dams in H. discus hannai and 297 individuals produced from 5 sires and 6 dams in H. discus discus, which evaluated by the Genetics and Breeding Research Center, National Fisheries Research & Development Institute(NFRDI). Genetic parameters were estimated for these abalone subspecies raised in Bukjeju branch, NFRDI, from May 20, 2004 to May 16, 2005, respectively. The heritability estimates obtained from restricted maximum likelihood(REML) were higher than expected, ranging from 0.40 to 0.43 for growth traits shell length, shell width and body weight in H. discus hannai and from 0.26 to 0.51 in H. discus discus, respectively. The heritabilities for shell shape and condition factor were lower than others of growth traits such as ranging from 0.09 to 0.19 in H. discus hannai and from 0.10 to 0.23 in H. discus discus, respectively. Genetic and phenotypic were > 0.93 between shell parameters and weight in two abalone species, respectively, indicating that breeding for weight gains could be successfully achieved by selecting for shell length.

• Journal of Aquaculture
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• v.19 no.2
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• pp.77-83
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• 2006

This study was conducted to investigate changes of hemolymph count, antioxidant enzyme activities (catalase: CAT and superoxide dismutase: SOD) and Heat Shock Protein 70 (HSP70) mRNA in hemolymph, hepatopancreas and gill of abalone (Haliotis sieboldii) exposed to various water temperatures. Abalones were exposed to 10, 15, 20, 25 or $30^{\circ}C$ for 0, 6, 12, 24 or 48 hours. Survival rate of abalone was 100% at 10, 15, 20 and $25^{\circ}C$, but 0% at $30^{\circ}C$. Hemolymph counts increased at lower water temperatures (10 and $15^{\circ}C$) and decreased at $30^{\circ}C$. SOD activity decreased immediately after exposure to lower or higher water temperatures compared to the control ($20^{\circ}C$) with an exception at $30^{\circ}C$ where the activity increased. At lower temperatures, SOD activity rose high after 24 hours, but decreased again at 48 hours. At $25^{\circ}C$, it decreased compared to the control. CAT activity decreased immediately after exposure to 10 or $25^{\circ}C$ compared to the control, and then was recovered to the initial level after increment. At $15^{\circ}C$, CAT activity was high after 6 hours, and then was recovered to the initial level after increment. At $30^{\circ}C$, the activity decreased throughout the experiment. The HSP70 mRNA expression in gill increased at lower temperatures compared to the control ($20^{\circ}C$) and $25^{\circ}C$. In this study, rapid change of wale, temperature caused stress response in abalone which had been raised at $20^{\circ}C$. At molecular level, HSP70 was expressed rapidly, but antioxidant enzymes like SOD and CAT were expressed later than HSP70. At 15 and $25^{\circ}C$ of water temperatures, the HSP70, SOD and CAT expression were stable with time. However, at $30^{\circ}C$, all abalone died possibly because they could not develop resistance to high temperature.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.7-12
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• 2012

The effect of water temperature on spawning induction, larval development, spat settling and its growth of the cockle shell, Fulvia mutica, were investigated to obtain the basic data for effective seed production. The eggs, which were randomly divided into 6 groups of water temperatures of 14, 17, 20, 23, 26 and $29^{\circ}C$, were transferred into 1 L beaker, respectively. The relationships between the water temperature and the required time (1/h, hour) by each egg developmental stage were calculated. Biological minimum water temperature and the cumulative water temperature until egg development of the veliger stage were calculated to be $0.1^{\circ}C$ and $397.3^{\circ}C$, respectively. The optimal water temperature for developmental bioassay of F. mutica was clarified to be $23^{\circ}C$. The required time for the embryo to become veliger larvae was 20 hours at $23^{\circ}C$.

• The Korean Journal of Malacology
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• v.29 no.2
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• pp.105-111
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• 2013

The gonadal development of triploid and diploid Pacific abalones, Haliotis discus hannai was histologically investigated in spawning season. Diploid abalones had matured oocytes and spermatozoa, but most triploid had spermatocytes or developing oocytes that was slightly retarded in gonadal development compared to diploid abalones. In spawning experiment of triploid and diploid abalones, spawning rates of diploid male and female were 100%, but those of triploid female was 50% and male was 25% respectively. Investigation of spawned abalone eggs and spermatozoa revealed that length of diploid sperms head were 17.47 ${\mu}m$, breadth of head were 10.31 ${\mu}m$, length of spermatozoa were 130.72 ${\mu}m$, but those of triploid spermatozoa were 11.83 ${\mu}m$, 7.89 ${\mu}m$ and 103.36 ${\mu}m$ respectively. Triploid spermatozoa were significantly small to diploid spermatozoa (p < 0.05). The eggs of diploid and triploid were not different in size. The cross experiment between oocytes produced by triploids and spermatozoa by diploids ($3n{\times}2n$ cross) revealed that no fertilization were occurred, and $2n{\times}3n$ cross also revealed same result.

• Journal of Aquaculture
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• v.9 no.4
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• pp.445-452
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• 1996

Endogeneous activities of ${\beta}-galactosidase$-like enzyme in various tissues from several finfishes and shellfishes were examined by histochemical analysis based on X-gal staining and by fluorimetric measurement using 4-methylumbelliferyl-${\beta}$-D-galactoside (4-MUG). Species used in this study were 3 freshwater fishes, mud loach (Misgurnus mizolepis), common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) ; 3 marine fishes, olive flounder (Paralichthys olivaceus), stone flounder (Kareius bicoloratus) and marbled sole (Limanda yokohamae) ; and 4 shellfishes, abalone (Haliotis discus hannai), Pacific oyster (Crassoskra gigas), pearl oyster (Pinctada fucata martensii) and ark shell (Anadara broughtonii). The activities of ${\beta}-galactosidase$-like enzyme in all finfishes examined were significantly different among species, with the wide variations between tissues in a species. In general, the tissues such as kidney, intestine and liver were ones which showed the significantly higher values in 4-MUG fluorimetry and deeper staining patterns in X-gal analysis compared to other tissues. On the other hand, serum and muscle revealed the significantly lower activities than others did, regardless of species. Shellfishes were also found to have endogenous activities of ${\beta}-galactosidase$-like enzyme which were significantly varied depending on both species and organs in a species. Hepatopancreas from all shellfishes examined showed the deepest pattern in X-gal staining and also the highest value in 4-MUG analysis, while activities of ${\beta}-galactosidase$-like enzyme in adductor muscles and mantle muscles from all shellfish species in this study except Pacific oyster were negligible : Pacific oyster had the significant activity of this enzyme in muscle tissues. Putative endogenous lacZ fragment was amplified from both finfishes and shellfishes by polymerase chain reaction (PCR). The molecular size of PCR products was about 510 bp, and there was no difference in size among species examined.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.3
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• pp.262-270
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• 2012

Seaweeds provide habitats in which marine animals can spawn and develop, and serve as a food supply for algaegrazing species such as sea urchins and abalone. Recently, seaweed species have disappeared from coastal ecosystems, leaving barren ground, defined as habitats that have lost their algae forests and where coralline algae containing calcium carbonate components have become encrusted on rocks. The biological causes of barren ground include grazing by herbivores and excessive seaweed harvest. The environmental harm caused by the spread of barren ground includes accelerated eutrophication following the reduction in seaweed, which plays an important role in oceanic purification. In the present study, we identified the relationships between various seaweed species and the occurrence of barren ground. Subtidal benthic macroalgal flora and community structure were observed seasonally on barren ground along vertical transects of rocky shores of Bihwa, Samchuck, and the east coast of Korea from February to November 2006. Fifty-eight seaweed species were identified, including 7 green, 15 brown, and 36 red algae species. There were between 6 and 28 species among seasons. Over the whole study period, average seaweed biomass (g wet wt $m^{-2}$) was 241.90 g, with a seasonal range of 25.26 to 760.34 g. Seaweed biomass declined with increasing seawater depth and ranged between 91.26 and 422.08 g. The vertical distribution of algae was characterized by Undaria pinnatifida and Sargassum honeri at 5 m, S. honeri and U. pinnatifida at 10 m, and U. pinnatifida and Agarum clathratum at 15 m depth. Seasonal patterns in community indices were not found. Community indices showed different patterns along vertical shoreline gradients; the dominance index increased but the richness, evenness, and diversity indices decreased with seawater depth. Sea urchin density was 8 to 24 individ. $m^{-2}$ in Bihwa. These urchin populations had significantly aggregated spatial patterns and recurrent destructive grazing appeared to be occurring.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.131-136
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• 2012

Growth, oxygen consumption, ammonia excretion, feeding and assimilation rate were examined from May 2010 to February 2011 in order to assess the physiological changes of Haliotis discus hannai in accordance with changes in season. The water temperature was in the range of $8-23.2^{\circ}C$ and the salinity in the range of 31.9-34.1psu during the examination period. The length of shell of Haliotis discus hannai grew from 36.3 mm to 66.1 mm in the 1 year old entities and from 60.6 mm to 66.1 mm for the 2 year old entities, while the weight of the meat increased from 3.16 g to 12.04 g and from 15.8 g to 21.5 g, respectively. The oxygen consumption and ammonia excretion rate displayed trend of increase in accordance with the increase in water temperature, while the feeding rate was high during the period from July to October. The assimilation rate was in the range of 68%-71% without significant difference between the age of the entities and seasons. SFG displayed +value throughout the year for the 1 year old entities of Haliotis discus hannai as well as for the 2 year old entities with the exception of the period of July, thereby showing that they are growing throughout the year. Therefore, there was no environmental effect including water temperature and salinity during the examination period.

• Journal of Aquaculture
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• v.10 no.3
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• pp.281-288
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• 1997

We investigated the optimal concentratin of ethyl-p-aminobenzoate for the exfoliation and recovery of young abalone, Haliotis discus hannai in according to different water temperatures, for the purpose of preventing the damage of shell and muscle to ecfoliated from shelter. In the 14$^{\circ}C$ water temperature, young abalones were exfoliated after 16, 35, 35 and 35 minutes in 150, 100, 75 and 50ppm concentration of ethyl-p-aminobenzoate, and were recovered after 100, 60, 30 and 30 minutes, respectively. Exfoliation rate of abalone were 100% except for 50 ppm (80%) and recovery rate were 100% of all concentration. In the $18^{\circ}C$ water temperature, young abalones were exfoliated after 4, 4, 6, 8, 8 and 12 munutes in 300, 200, 150, 100, 75 and 50ppm concentration of ethyl-p-aminobenzoate, and were recovered after 210, 180, 90, 60, 30, 20 and 20 minutes, respectively. Exfoliation rate of abalone were 100%, and recovery rate were 100% except for 200 and 300ppm (90%). In the $24^{\circ}C$ water temperature, young abalones were exfoliated after 8, 10, 10 and 12 minutes in 150, 100, 75 and 50ppm concentration of ethyl-p-aminobenzoate, and were recovered after 70, 50, 30 and 20 minutes, respectively. Exfoliation and recovery rate of abalone were 100%. In the 18$^{\circ}C$water temperature, exfoliation rate that treated with freshwater during 20 minute were 80, 50, 30 and 5% in 100, 75, 50 and 25% of fresh water, and recovery after 60, 15, 10 and 2 minutes, respectively and recovery arate were 100% except of r 100% freshwater. In this study, we suggest the reslults that the exfoliation and recovery by ethly-p-aminobenzoate were more effected in $18^{\circ}C\;and\;24^{\circ}C$ of sea water temperature than those of $14^{\circ}C$. The optimal concentration of ethyl-p-aminobenzoate was 50ppm at those water temperature. We raised 20 individual of young abalones at water temperature of $16^{\circ}C$ in the 1$\ell$ o ftnk and checked the variatin of dissolved oxygen (DO) by respiration of abalones that treated with 75ppm of ethyl-p-aminobenzoate. Before anesthetizion, DO were 6.17~6.20mg/$\ell$ and slowly decreased. But after 60 minutes, DO decreasing were stopped in 5.42~5.46mg/$\ell$. On the other hand, the control was continuously decreased and 5.27mg/$\ell$ after 60 minutes. The heartbeats of abalones were 33~45/minute in the water temperature of $18^{\circ}C$, but that treated with 100 ppm concentration of ethyl-p-aminobenzoate during 60 minutes, was 0/minute. And heartbeats of recovered abalones from anesthetizion were 29~43/minute.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.3
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• pp.208-214
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• 2008

This study monitored a variety of marine communities during monthly or bimonthly censuses from February 1999 to August 2000. The communities investigated included artificial reefs composed of various substrates, which were placed on an area of sandy bottom at 8, 10, and 13m depths in Muronohana, Ikata, Shikoku, Japan. Economically important shell fishes, such as the turban shell and abalone, appeared on the artificial reefs after 1 month of construction. Shell fishes were recorded at levels of five to 20 individuals per reef. A total of 37 species (4 orders, 19 families) were identified during the experimental period. Apagon semilineatus, Trachurus japonicus, Pteragogus sp., and Pterogobius elapoides accumulated over an average of 100 individuals during the study period. Apagon semilineatus, Pteragogus sp., and P. elapoides accumulated over 1,000 individuals on all artificial reefs in May 1999. Trachurus japonicus reached well over 500 individuals in the artificial iron reef during June and July 2000. Higher monthly variation in fish abundance occurred during periods of high temperature, as compared to periods of low temperature between December 1999 and March 2000. More fish were observed in the artificial iron reef than in the artificial concrete reef, because the former offered a broader inner space and the shadows of the roofs served as a shelter for fish.