ISSN : 1225-3480
This study investigated the Korean name of imported fishery mollusks in order to reduce the value of domestic fishery mollusks and the damage to consumers. And it tried to review and redefine the Korean name of 50 foreign mollusks that are being imported or are likely to be imported in the future.
The mitochondrial genome (mitogenome) of the invasive and harmful polychaete species, Polydora hoplura (Annelida), was analyzed by next generation sequencing (NGS). Its mitogenome was found to be 17,597 bp in length, comprising 13 protein-coding genes, two ribosomal RNA genes, and 23 transfer RNA genes, with one additional trnM gene. The gene composition and order of P. hoplura were distinct from those of polychaetes and even differed from those of Marenzelleria neglecta belonging to the same family, Spionidae.
Protozoan parasite species of the genus Perkinsus have been known to infect various venerid clams and induce pathological functions. In this study, polymerase chain reaction (PCR) analysis using species-specific primers was conducted to investigate Perkinsus olseni and Perkinsus honshuensis infections in Ruditapes philippinarum and Ruditapes variegatus collected from the coast of Dongil-ri harbor and Hamo beach, Daejeong, Jeju, Korea in the winter of 2020. Based on the results of an investigation on the infection of the two parasite species in the two host species, it was confirmed that only R. variegatus specimens collected from the Hamo beach were infected with P. olseni. Previous studies have reported R. variegatus as a host for P. honshuensis, but based on the findings of this study, it is suggested that this clam species could be infected by not only P. honshuensis but also by P. olseni.
As demand on live and half-shell oysters increases globally, the appearance of the oyster is becoming one of the important determinants of marketability. In terms of oyster shape, cultchless single oysters have advantages over the conventional cultched oyster, as the shape of a single oyster is intermittently managed during the grow-out period, resulting in round individuals that are consistent in shape and size. Although a growing number of oyster producers in Korea culture cultchless single oysters, there is no consensus on ‘good-looking shape’ and high marketability among oyster producers and consumers. In this study, we applied three known oyster grades (total weight, SL:SH, and SL based) to Pacific oyster groups to assess the feasibility of the grading system. In addition, the mean condition index (CI) of the oysters corresponding to each category in the grade was compared to decide traits that could be applied in oysters produced in Korea. A total of 888 collected oysters includes diploid oysters reared by long-line culture (2-yrs, 113.9 ± 18.5 mm in SL), diploid (1-yr, 79.5 ± 11.7 mm), and triploid (3-yrs, 152.7 ± 22.6 mm) oyster reared individually in hexagonal plastic containers. The results revealed that the Canadian SL/SH-based grade was applicable, as the single oyster groups with the upper grades demonstrated significantly higher CI than those in the lower grades. We also found a positive correlation between SH/SL ratio and CI in the single oyster group, indicating that oysters with the teardrop shape tend to show a higher CI. It was also notable that any of the traits were not correlated with CI in the cultched oyster group. Thus in this study, we suggest SL/SH ratio as a single oyster trait that could be utilized in oyster grading system.
To optimize the cultural performance for oyster rack culture in tidal flat, the scope for growth (SFG) and food availability (FA) were estimated from primary production and the metabolic rates of the oysters cultured on the northeastern coast of Wando Island, Korea. The estimated unit energy content of the seawater ranged from 1.18 to 25.39 Kcal/m3/day in typical productive features of the temperate zone. The absorbed energy allocated in the order of respiration (15.9-97.3%), meat growth (0-70%) and shell growth (0.9-31.8%), respectively . Scope for growth (SFG) ranged from ―2.2 to 45.0 Kcal/m3/day regulated by mainly temperature and salinity. Food availability (FA) ranged from 1.1 to 329 which met food requirements resulting in no mortality. Between the late spring and summer season , low FA resulted in food deficiency and further served as a factor for mortality when especially coupled with physical stress such as typhoons . The energetic cost of reproduction infferred from summer mortality corresponded to 15% for one year-old and 60% for 2 year-old oyster . Our results indicated that one of the factors for effective oyster culture , stocking time should be determined upon consideration of spat size. Small -sized spats in shell height should introduce in spring but large-sized (> 5 cm) in autumn to achieve the commercial oyster before next summer without significant mortality.
In this study, we evaluated the effect of inland pollution sources on seawater and oyster (Crassostrea gigas) in Kamak bay after rainfall events. We analyzed the sanitary indicator microorganism such as coliform group, fecal coliform and Escherichia coli (E. coli) in the discharge water of major inland pollutants, seawater and oyster for 3 days after 27.6 and 58.0 mm rainfall events. According to these results, the range of coliform group and fecal coliform was 1.8-540 and <1.8-240 after 27.6 mm rainfall and was from <1.8 to 54,000 and from <1.8 to 9,500 MPN/100 mL after 58.0 mm rainfall in the discharge water of 5 waste water treatment plants. Also The range of fecal coliform and radius of impacted area of 10 contaminants (stream and domestic waste water) was from 63 to 230,000 MPN/100 mL and from 10 to 2,044 m, respectively. The fecal coliform of seawater at 16 stations in the designated area and 19 stations non-designated area ranged from <1.8 to 4.5 and from <1.8 to 540 MPN/100 mL, respectively. And The E. coli level of oyster at 5 station in the designated area ranged from <18 to 330 MPN/100 g.
Clithon retropictus is a small gastropod belonging to the Neritidae, and inhabits gravel areas in brackish waters. It has been designated as an endangered species as class II, because of its habitat conditions and reckless development of coastlines. In September 2021, C. retropictus registered in NCBI has only 80 nucleotides, 52 proteins, and 74 genes. In this context, we sequenced the C. retropictus cDNA library using the Illumina Hiseq 2500 platform. Arginine Kinase (AK) sequence was obtained by using BLAST program. To investigate the molecular phylogenetic analysis of C. retropictus, a dendrogram was generated using AK gene as a marker. Based on the phylogenetic tree, it is classified into three classes (Cephalopods, Gastropods, and Bivalvia). In addition, analysis of AK 2D structure using 38 species shows that no striking similarity was found. In conclusion, AK gene of C. retropictus consisted of 1,053 bp (351 amino acids) and could be utilized for molecular phylogenetic classification.
