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ISSN : 1225-3480
During a deep-sea marine biodiversity survey, Punctulum flavum (Okutani, 1964) was discovered at depths ranging from 900 to 1,000 m in the East Sea, Korea. The genus Punctulum Jeffreys, 1884 is a minute rissoid group comprising six valid species, most of which inhabit the bathyal zone of the northwestern Pacific. Among them, Punctulum flavum has been reported from Japan and Russia and is known to exhibit considerable morphological variations in shell shape, sculpture, and protoconch characteristics. A detailed examination of shell morphology, including high-resolution SEM observations of the protoconch and teleoconch, indicated that the Korean specimens correspond to a "deep-water form" (sensu Hasegawa, 2014). The shells exhibit an inflated ovate-conical form and a thin periostracum; the protoconch bears closely spaced flat spiral cords, and the teleoconch is sculptured with weak but distinct axial riblets and fine spiral cords. The discovery of P. flavum in Korea extends the southwestern limit of its known distribution, providing valuable insights into the bathyal rissoid fauna of the northwestern Pacific and the genus Punctulum.
The terrestrial slugs Ambigolimax valentianus (Limacidae) and Deroceras leave (Agriolimacidae) are significant agricultural pests globally. Their widespread distribution is largely driven by anthropogenic activities, particularly the international trade of plant materials and soil containing their eggs or juveniles. Although these species are designated as Alert Alien Species in Korea considering the potential threat to native ecosystems, their presence in the field has not been officially verified so far. Here, we report the first confirmed occurrence of A. valentianus and D. laeve in South Korea based on morphological characteristics and molecular analysis of the cytochrome c oxidase subunit I (COI) gene. Specimens were collected from various regions in South Korea, humid habitats near human dwellings. Our findings suggest that these invasive slugs may have already established populations in Korea, highlighting the need for continuous monitoring and management strategies.
Molluscan shells are widely used for ornamental and scientific purposes, yet their preservation quality varies depending on specimen processing methods. As shells are increasingly recognized as substrates providing morphological, chemical, and molecular information, the selection of appropriate processing strategies has become increasingly important. This study compared shell preservation characteristics of Anadara broughtonii under different specimen processing methods to identify relatively stable treatment conditions. Experimental groups included a water-rinsed control, natural decomposition in water followed by rinsing, ethanol fixation at 70-75% and ≥ 99%, and hot-water treatment applied at the stages of adductor muscle relaxation and soft tissue removal. Shell external structures, periostracum retention, cracking patterns, and inner surface preservation were assessed using stereomicroscopy combined with image focus stacking. Preservation outcomes differed among treatments, particularly in external appearance and periostracum retention. Overall, ethanol fixation at 70-75% was identified as a relatively stable processing method when both preservation quality and practical handling were considered. These findings highlight the importance of selecting specimen processing methods according to the intended use of molluscan shell specimens and provide baseline information for establishing preservation strategies for ornamental collections and morphological research.
We examined the hemocyte types and immune function of Ruditapes aspera from the sandy-pebble intertidal zone in Wimi Harbor on Jeju Island, using microscopy and flow cytometry. Three types of hemocytes were identified under light microscopy: granulocytes, hyalinocytes, and blast-like hemocytes. The ratio of nuclear size to cell size (N/C) of blast-like cells (0.77 ± 0.09) was slightly larger than that of granulocytes (0.52 ± 0.08) and hyalinocytes (0.65 ± 0.09). The N/C ratios of R. aspera hemocytes were similar to those of R. philippinarum (granulocyte 0.55 ± 0.06, hyalinocyte 0.61 ± 0.07, and blast-like cell 0.75 ± 0.07) collected from Jeju Island. Flow cytometry revealed that R. aspera contained 7.8 ± 1.1 × 105 hemocytes, which is similar to that of R. philippinarum (10.0 ± 1.4 × 105 cells). Among the three types of hemocytes in R. aspera, hyalinocytes accounted for 69.2% of the total hemocytes, followed by granulocytes (18.2%) and blast-like cells (10.2%). The lysozyme content, a proxy for the innate immune capacity of invertebrates, was highest in granulocytes (9.9 ± 3.2 × 104 A.U.), significantly higher than that in hyalinocytes (2.1 ± 0.4 × 104 A.U.), indicating that, like other marine bivalves, granulocytes are the main cells involved in defense. Phagocytosis rates measured by flow cytometry also showed that granulocytes in R. aspera are the primary defense cells, with a rate (58.5 ± 17.8 after 90 min) significantly higher than that of hyalinocytes (10.3 ± 5.5; ANOVA, P < 0.05). Similarly, reactive oxygen species (ROS) production in granulocytes (4.1 ± 3.0 × 106 A.U. after 120 min) was significantly higher than in hyalinocytes (4.1 ± 3.0 × 106 A.U. after 120 min), confirming granulocytes as the key hemocytes involved in defense.
The sustainable growth of abalone (Haliotis discus hannai) aquaculture requires reliable systems for seed quality verification and health assessment. Conventional morphological indicators are limited in sensitivity and speed, highlighting the need for molecular biomarkers. Differentially expressed genes (DEGs) identified through next generation sequencing (NGS) offer promising candidates, but their applicability as biomarker genes must be validated under controlled stress conditions. Juvenile abalones (2.2-2.3 cm shell length) were subjected to mechanical injury and oxidative stress (H2O2 exposure). Gill tissues were sampled at 3 h and 18 h post treatment, and gene expression was analyzed by quantitative real‑time PCR (qPCR). Candidate biomarker genes included ferritin, Hsp70, IL‑17, and NF‑κB, representing oxidative defense, stress response, immune activation, and inflammatory regulation, respectively. Ferritin expression was significantly upregulated under both mechanical injury and oxidative stress, with the highest induction at 18 h, reflecting its role in iron storage and oxidative defense. Hsp70 showed rapid induction at 3 h, consistent with acute stress responses, and remained elevated at 18 h. IL‑17 expression increased at both time points, indicating sustained immune activation in response to tissue damage and oxidative stimuli. NF-κB expression increased after 3 and 18 h, highlighting the role of NF-κB in initiating and maintaining the inflammatory response. These findings demonstrate that ferritin, Hsp70, IL‑17, and NF‑κB are responsive to mechanical and oxidative stress, supporting their utility as biomarker genes for assessing abalone health. The study establishes an experimental model to evaluate the applicability of NGS‑derived DEGs as biomarkers, providing a foundation for the development of molecular based systems for seed quality verification and aquaculture health monitoring. Ultimately, this approach is expected to contribute to the sustainable growth of the abalone industry by improving disease resistance, enhancing stock quality, and advancing health management strategies.
This study was conducted to analyze the stock abundance and population dynamics of the bivalve Keenocardium buelowi inhabiting the coastal waters near Yokji Island, Tongyeong, and to propose appropriate management strategies. From May to December 2024, six dredge surveys were performed, and shell length, body weight, and age composition were analyzed using stock dynamic models. The instantaneous total mortality coefficient (Z), natural mortality coefficient (M), and fishing mortality coefficient (F) were estimated as 0.982, 0.724, and 0.258 per year, respectively, while the age at first capture (tc) was 3.28 years. The mean density was 4.89 individuals/m2 (192.3 g/m2 in unit biomass), and the total stock biomass was estimated to be approximately 323.1 tons. The application of the Beverton-Holt model suggested that maximum yield could be achieved by reducing tc to 2-2.5 years and increasing fishing mortality above 2.0; however, this approach could lead to overexploitation. For sustainable harvesting, maintaining tc above 3.0 years and fishing intensity at 1.5 was found to be optimal, yielding an acceptable biological catch (ABC) of 198.1 tons. Although the K. buelowi stock in the Yokji waters is currently under low fishing pressure, significant natural mortality occurs due to the collapse of the thermocline after summer. Therefore, systematic management-based on the Fisheries Resources Management Act and the Fisheries Act-is required, including the designation of the area as a fisheries management zone, to ensure adaptive management in the face of future climate change.
