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ISSN : 1225-3480
PAHs (Polycyclic Aromatic Hydrocarbons: PAHs) is the hydrophobic inorganic material composed of carbon and hydrogen that is easily adsorbed biological organisms in the ocean. Bivalves is the indicator of environment monitoring because of reflect growth, physiological response of bivalve followed their habitat environment. The aim of research is understand the change of oysters (Crassostrea gigas) physiological response under exposed PAHs concentration for control, 1, 10 and <TEX>$100{\mu}g/L$</TEX>. We investigated induced immune change response for oyster hemocyte and effect of tissue RNA/DNA ratio for mantle, gill and adductor muscle individually. As a result of experiment change of immune response the oyster hemocyte when exposed PAHs showed that viability and adhesion is no significant difference (ANOVA test, p < 0.05). However phagocytosis decreased under the over <TEX>$10{\mu}g/L$</TEX> of PAHs concentration and ROS increased with the increase of PAHs concentration. The change of RNA/DNA ratio is R/D ratio decreased with the increase of PAH concentration in adductor muscle. However gill and mantle showed no change of R/D ratio with PAHs concentration. The oysters when exposed inorganic pollutant that decreased of physiological condition and damaged protein synthesis of adductor muscle.
Mussels have been commonly used in bioassay for quality assessments of environment. Moreover, several standard protocols for the developmental bioassay of bivalves have been proposed. In this study, the EC50 of polycyclic aromatic hydrocarbons (PAHs) was determined using mussel, Mytilus galloprovincialis embryonic developmental bioassay. To determine the sensitivity of M. galloprovincialis, their fertilized eggs were exposed to five PAHs (2-metylnaphthalene, fluorene, dibenzothiophene, phenanthrene, pyrene). The EC50 of 2-metylnaphthalene, fluorene, dibenzothiophene, phenanthrene, and pyrene were 232, 273, 67.9, 43.2, and <TEX>$33.1{\mu}g/L$</TEX>, respectively. The overall sensitivity of M. galloprovincialis in the present developmental bioassay was similar to or more sensitive than that of other marine organisms commonly used in aquatic bioassays. The results of this study could be provide with fundamental data of setting standard for protection of marine life and or can use prediction the aquatic toxicity of PAHs.
A significant production decrease has been witnessed for the Pacific oysters, Crassostrea gigas farmed in the western coastal waters of Korea, presumably by the loss of physiological viability. We evaluated the viability in terms of health indicators, the condition indices and hemocyte apoptosis rates of the oysters inhabiting two representative farming sites, Incheon and Taean each with different environmental variables. In our monthly measurements for the whole year 2013, the indicators were location specific. The condition indices of Incheon were highly variable, 1.67-8.58%, while those of Taean were less, 2.28-5.57%. The condition indices decreased during the spawning seasons, July and September in common. The two oysters exhibited also differed in the apoptotic activities of hemocyte, highly active, 4.03-30.15% for Incheon oysters and less active, 2.87-17.48% for Taean oysters. One thing we could identify was the two measurements were adverse during the critical seasons of spawning, reminiscent of being a useful tool for a health indicator for the oysters. Similar trend was also observed in the time when change in temperature was extreme. The findings in this study are highly indicative of health indicators for the oyster aquaculture.
Single nucleotide polymorphisms (SNPs) are widely acknowledged as the marker of choice for many genetic and genomic applications because they show co-dominant inheritance, are highly abundant across genomes and are suitable for high-throughput genotyping. Here we evaluated the applicability of SNP markers developed from Crassostrea gigas and C. virginica expressed sequence tags (ESTs) in closely related Crassostrea and Ostrea species. A total of 213 putative interspecific level SNPs were identified from re-sequencing data in six amplicons, yielding on average of one interspecific level SNP per seven bp. High polymorphism levels were observed and the high success rate of transferability show that genic EST-derived SNP markers provide an efficient method for rapid marker development and SNP discovery in closely related oyster species. The six EST-SNP markers identified here will provide useful molecular tools for addressing questions in molecular ecology and evolution studies including for stock analysis (pedigree monitoring) in related oyster taxa.
Spermatid differentiations during spermiogenesis and sperm ultrastructures in male Mercenaria stimpsoni were investigated by transmission electron microscopic observations. In the early stage of the spermatid during spermiogenesis, a few granules and a proacrosomal granule, which is formed by the Golgi complex, become a proacrosomal vesicle. Consequently, it becomes an acrosome by way of the process of acrosome formation. The morphologies of the sperm nucleus type and the acrosome of this species have a curved cylindrical type and cap shape, respectively. The spermatozoon is approximately <TEX>$48-51{\mu}m$</TEX> in length including a curved cylinderical sperm nucleus (about <TEX>$4.18{\mu}m$</TEX> long), an acrosome (about <TEX>$0.52{\mu}m$</TEX> in length) and tail flagellum (<TEX>$42-45{\mu}m$</TEX> long). As some ultrastructural characteristics of the acrosomal vesicle, the peripheral parts of two basal rings show electron opaque part (region), while the apex part of the acrosome shows electron lucent part (region). These charateristics of the sperm belong to the family Veneridae in the subclass Heterodonta, unlike a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part (region). Therefore, it is easy to distinguish the families or the subclasses by the acrosome structures. Exceptionally, In particular, a cylinder-like nucleus of the sperm is curved (the angle of the nucleus is about <TEX>$80^{\circ}$</TEX>), as seen in some species of Veneridae (range from <TEX>$0^{\circ}$</TEX> to <TEX>$80^{\circ}$</TEX>). The number of mitochondria in the midpiece of the sperm of this species are four, as one of common characteristics appeared in most species except for a few species in Veneridae in the subclass Heterodonta. Cross-sectioned axoneme of the sperm tail flagellum shows a 9+2 structure.
The effects of different stocking densities on the growth and survival rate of the abalone, Haliotis discus hannai, were investigated in marine net cage for two years. Stocking density was set 15, 30, 45 and 60 percentage <TEX>$(=per.)/m^2$</TEX> with share to cross-sectional area per shelter. The primary rearing period (PRP) and the secondary rearing period (SRP) were conducted by a year. One year mean water temperature of PRP and SRS showed the difference about <TEX>$2^{\circ}C$</TEX>. In the growth (initial mean shell length of abalone : <TEX>$36.14{\pm}2.28mm$</TEX>) of PRP, the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rate (SGR) of the <TEX>$15per./m^2$</TEX> were higher than those of density groups (P < 0.05). Survival rates of all density groups were showed no significant difference. In the growth (mean shell length of abalone : <TEX>$55.26{\pm}6.93mm$</TEX>) of SRP, ARG, DGR and SGR of stocking density groups showed no significant difference except for <TEX>$45per./m^2$</TEX> density group. Survival rate in the low-density (15, <TEX>$30per./m^2$</TEX>) was more than 70%, and those of the high-density (45, <TEX>$60per./m^2$</TEX>) were less than 31% and 9%, respectively. These results showed that the appropriate stocking density for <TEX>$15per./m^2$</TEX> was seven hundred fifty number per one net cage (<TEX>$2.4{\times}2.4m$</TEX>), during PRP using 3-4 cm abalone in length. Also for the secondary rearing period, the optimal stocking density (shell length 5-6 cm of abalone) consider with the economical efficiency was determined to be <TEX>$30per./m^2$</TEX>, resulting the productivity improved.
The effect of different feeding rate on the growth and survival rate of the abalone, Haliotis discus hannai, were investigated in marine net cage culture and indoor tank culture. Feeding rate is determined that was fed 5, 10, 15 and 20 percentage to abalone at body weight once daily : 5 daily feeding rate (DFR), 10DFR, 15DFR and 20DFR. After that, it was conducted to reared during thirteen month with two replicates in net-cage culture and indoor tank culture. In the growth performance of reared abalone (initial mean shell length <TEX>$54.18{\pm}7.39mm$</TEX>) in net cage culture, that the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rate (SGR) to the shell length and shell breadth, as well as weight gain (WG), daily weight gain (DWG) and specific weight gain (SWG) to body weight of 20DFR were lower than those of different groups (P < 0.05). Also, survival rates of 20DFR was lower than those of different groups (P < 0.05). In the growth performance of reared abalone (initial mean shell length <TEX>$49.70{\pm}2.28mm$</TEX>) in indoor tank culture, that the ARG, DGR and SGR to the shell length and shell breadth, as well as WG, DWG and SWG to body weight of 5DFR and 10DFR were lower than those of different groups (P < 0.05). And also, survival rates of 20DFR was lower than those of different groups (P < 0.05). Therefore, these results is showed that the daily feeding rate for natural feed in net-cage culture and indoor tank culture should be to supply among 5-10 percents, taking into account growth, survival rate and economical efficiency.
This study was conduct to investigate the effect of Intermediate culture types on the growth and survival rate of the abalone, Haliotis discus hannai, in net cage and indoor tank. Intermediate cultures were to determine there that was to setting at marine net cage culture (NCC) in net cage, floor culture (FC), net floor culture (NFC), double shelter culture (DSC) and indoor net cage culture (INCC) in indoor tank, in two replicate. In the growth performance of juvenile abalone reared through intermediate culture, that the absolute growth rate (<TEX>$AGR_{SL}$</TEX>, <TEX>$AGR_{SB}$</TEX>), daily growth rate (<TEX>$DGR_{SL}$</TEX>, <TEX>$DGR_{SB}$</TEX>), and specific growth rate (<TEX>$SGR_{SL}$</TEX>, <TEX>$SGR_{SB}$</TEX>) to the shell length <TEX>$(_{SL})$</TEX> and shell breadth <TEX>$(_{SB})$</TEX> of NCC were higher than those of different groups (P < 0.05). As weight gain (WG), daily weight gain (DWG) and specific weight gain (SWG) to body weight through intermediate culture types in indoor tank was not significant. Also that, survival rate among experimental groups of intermediate culture in indoor tank was not significant. Therefore, these results is showed that should to cultivate for net cage so that intermediate culture of juvenile abalone over 2 cm, accordingly research to effective progress of juvenile abalone intermediate culture in indoor tank be should from various reason as well as feed and rearing condition.
This study histologically describes the gonadal development and reproductive cycle of the abalone, Haliotis discus hannai inhabiting Jindo on the southern seashores of Korea. Gonads displayed histologically definitive seasonal changes. The female ratio (F/F + M) was 57% (n = 154/271). The gonad index (GI) of both males and females was the highest (3.3 and 3.9) in June and was the lowest (1.1 and 1.1) in December. The condition index (CI) and meat weight rate (MWR) were highest in May and lowest in October. The pattern of changes in the GI, CI and MWR were similar to the pattern of seasonal changes in gonadal tissues. The reproductive cycle was divided into an inactive stage (November-December), early active stage (January-March), late active stage (March-April), ripe stage (May-June) and spent and degenerative stage (July-October). The main spawning period of Haliotis discus hannai was July to August at Jindo in 2013.
Phytoplankton species composition and ecological index (diversity, evenness, richness and dominance) were analysed from April 2013 to March 2014 at 10 stations of cupped oyster, Crassostrea gigas culture area in Iwon coast, Korea. Seasonal and positional variation of phytoplankton standing crops, biomass, dominant species and water quality were distinctively different according to occasionally inflow of Iwon dam reservoired water. The composition of phytoplankton species were Bacillariophyceae 98, Dinophycease 22, Chlorophycease 13, Cyanophyceae 8, Silicofalgellate 4, Euglenophyceae 2, Cryptophyceae 1 species. The most dominant species was Bacillariophyceae as 64.0%. The highest biomass of phytoplankton recorded in September as <TEX>$40,910{\times}10^3$</TEX> cell/L at the station 1, near from inland water inflow area. Ecological indices (diversity, richness, evenness, and dominance index), used for structural change of phytoplankton community and water quality (temperature, dissolved oxygen, salinity) showed difference of spatiotemporal property also.
This study was conducted to investigate the impact of sand addition to an intertidal for the development of the Manila clam habitat on benthic community structure. For this, we focused on the spatio-temporal changes in the surface sediment condition and benthic community structure including Manila clam before and after the event. Study site was the lower part of Ojjeom tidal flat in Gonam-myeon, Taean-gun where sand added to on July 2010. We set three stations at each of sand adding area (experimental plot) and non sand-adding area (control plot) and did sampling works ten times from June 2010 to October 2011. Directly after the event, surface sediments changed to very coarse sand, but the state was not maintained over two months because of seasonal sedimentation and finally got back to the original grain sizes in eight months. The number of species and density were temporarily reduced right after the event and polychaetes such as Sternaspis scutata, Ampharete arctica were most negatively affected by the event. However, the number of species and density quickly recovered from the reduction in four to six weeks owing to the recolonization by the existing species and species in the vicinity of the plot. However, despite the recovery of ecological indies, species composition was continuously changed from one to another, thereby community structure stayed unstable condition, especially in some stations with finer sediment in their original condition. After sand addition, density of Manila clam was prominently increased at only one station with coarser sediment in its original condition.
The mass mortalities have been occurring of Korean scallop Patinopecten yessoensis from 1997's to now in Korea east sea. Cages behavior and interference effect (common name; curtain effect) between scallop cages were investigated in culture grounds on the eastern coastal waters of Korea for understand to mechanism of rising about mass mortalities of Korean scallop quickly. The first experiment was carried out in circulating water channel to assess inclination angel from relationship between velocity and cages interval, velocity with culture cages position. An angle of inclination of scallop culture cages were 94.6 to 92.3 degree under a several velocity which were from 0.1 m/s and 131.9 to 118.1 degree under 0.5 m/s with cages interval were 1 m, 94.3 to 91.0 degree under velocity is 0.1 m/s and 133.2 to 122.4 degree under 0.5 m/s with cages interval were 1.5 m and 94.6 to 96.4 degree under velocity is 0.1 m/s and 131.7 to 131.8 under 0.5 m/s with cages interval were 2 m. The second experiment was designed to prove the tank test. Velocities were measured inside and outside of the scallop culture ground at eastern sea of Korea. The velocity of inside of the culture was the slowest as 0.1m/s. In this result, interference between former cage and after cage was occurred.
The biogeography and diversity patterns of the marine bivalve molluscan fauna of the East Sea coast of South Korea are analyzed. The total species richness of the continental Korean bivalve fauna, excluding insular regions (Dok-do and Ullung-do), is 304, and from north to south the species richness of bivalves increases showing a clear gradient: Gangwon, 143 species <TEX>${\rightarrow}$</TEX> Gyeongbuk, 131 <TEX>${\rightarrow}$</TEX> Gyeongnam, 183. A zonal-geographical analysis of the entire fauna shows that the great majority are warm-water mollusks, constituting 77% (subtropical, 37%, tropical-subtropical, 30%, subtropical-boreal, 10%), The number of boreal (low-boreal, widely distributed boreal and circumboreal) species is lower, 19%, whereas boreal-arctic mollusks have only 4%. This demonstrates that the bivalve molluscan fauna of the eastern coast of Korea is subtropical, and has more affinities to the fauna of the East China Sea than to the northern East Sea. Separate analysis by provinces shows the increasing role of warm-water mollusks from north to south. While tropical-subtropical and subtropical species constitute 47% (68 species) in Gangwon, their dominance increases to 71% (93 species) in Gyeongbuk, and to 80% (148 species) in Gyeongnam. The Gyeongnam bivalve fauna is the most diverse in species composition and has the largest number of "endemics" (species known only from this province), 46%. The Gangwon fauna also contains many "endemics", up to 40%, while Gyeongbuk is an intermediate zone with low "endemicity", only at one-fifth of the regional fauna, and has the most species in common among the three provinces.
Finless porpoise is the one of porpoises in Korean waters that frequently observed in the coastal area. This study reported parasite infection cases of stranded finless porpoise, Neophocaena asiaeorientalis which was stranded on the Saemangeum Dyke on the west coast of Korea 21 May, 2012. The finless porpoise was male, and estimated at 8 years old. Parasites were found in abdominal cavity, skull and lung. The parasites were identified as nematode, trematoda and lungworm. Nematoda in abdominal cavity was Crassicauda sp. Trematoda found in the skull was indentified Nasitrema sp. Lungworm in lung seemed one of genus Pseudaliids. Anisakis spp. has not been found.
We report three new records Korean marine gastropods. The new record species are Hipponix acuta, Lyncina (Ponda) carneola, and Velutina (Velutella) plicatilis cryptospira. As a result, the family Hipponicidae in Korea turned out to be 5 species of 4 genera, Cypraeidae are 14 species of 8 genera, and Velutinidae are 7 species of 3 genera, respectively.
