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메뉴Four molluscan species‒Amicula gurjanovae Yakovleva, 1952, Nipponacmea nigrans (Kira, 1961), Coralliophila carnosa Kosuge, 1986, and Sepia furcata Ho & Lu, 2005‒are reported for the first time from Korean waters. Within the genus Amicula, only two valid species are currently recognized worldwide: A. amiculata (Pallas, 1788) and A. gurjanovae Yakovleva, 1952. A. gurjanovae is considered a rare species, previously known only from the southern Kuril Islands and southern Sakhalin. N. nigrans is distinguished by its non-protruding apex, dense riblets, and gray pigmentation on the snout and sides of the foot. C. carnosa is similar to C. pulchella and C. morishimai, both known to occur in Korean waters. However, it can be distinguished by its more slender shell, less angular shoulder, and more numerous and pronounced spiral cords. The S. furcata specimen identified in this study was slightly larger than in the original description and exhibited an arm formula of 2 > 3 > 4 > 1. For each species, we provide detailed morphological descriptions, high-resolution images, and partial mitochondrial cox1 sequences as DNA barcode references.
This study provides a comprehensive long-term analysis of the diversity and distribution patterns of marine mollusks inhabiting rocky shore ecosystems along the coast of Uljin, Gyeongbuk. From August 2012 to February 2024, surveys were conducted eight times at 11 stations over approximately 12 years using scientific diving and quadrat sampling methods. A total of 124 molluscan species belonging to 45 families, 18 orders, and 4 classes were identified, with Gastropoda showing the highest species richness (79 species, 63.7%). Analysis of vertical distribution revealed distinct differences in species composition between habitats, with 29 species recorded in the intertidal zone and 108 species in the subtidal zone. Dominance analysis indicated that the periwinkle Echinolittorina radiata and the mussel Modiolus kurilensis were the primary and secondary dominant species, respectively, representing key components of the rocky shore ecosystems molluscan community in Uljin. Long-term monitoring also revealed the emergence of new species such as Turbo cornutus, Chlorostoma turbinatum, Omphalius pfeifferi pfeifferi, Lacuna turrita, and Mitrella bicincta. Notably, the occurrence of the subtropical species Turbo cornutus suggests that rising seawater temperatures driven by climate change are influencing the structure and distribution of mollusks along the East Sea coast. This study provides fundamental data on molluscan diversity in the rocky shore ecosystem of Uljin and offers important scientific evidence for understanding the long-term ecological impacts of climate change on the marine ecosystems of the East Sea.
This study analyzed the movement distance and locomotion speed to understand the mobility of Unionidae (Anodonta woodiana, Unio douglasiae). In the sand area of the Nakdong River, the average movement distance was measured to be 296.5 cm for the A. woodiana and 395.1 cm for the U. douglasiae. In the mud area, the average movement distance for the A. woodiana was 257.0 cm, U. douglasiae was 254.7 cm. Both species moved a long distance in the sand area. In a lab tank, the average locomotion speed of A. woodiana was 39.1 cm/hr. In the sand area of the Nakdong River, the average locomotion speed for the A. woodiana was 61.1 cm/hr, U. douglasiae was 122.7 cm/hr. In the mud area, the average locomotion speed for the A. woodiana was 69.1 cm/hr, U. douglasiae was 67.8 cm/hr. The results showed that the locomotion speed of U. douglasiae was faster than that of A. woodiana. The analysis of the correlation between size and locomotion speed showed that the Spearman's rank was positive in both sand and mud areas. The analysis showed no significant difference between individual size and locomotion speed (P > 0.05), which means that larger individuals tend to have a faster locomotion speed. Based on the study's findings, it is believed that controlling the discharge amount and rate of dams, lakes, and weirs could help secure the survival stability of freshwater mollusks.
The Manila clam Ruditapes philippinarum is an ecologically and economically important bivalve in Korean tidal flats. To examine seasonal patterns in reproduction and health, we monitored monthly changes in gonadal development, condition index (CI), trematode infection, and Perkinsus olseni infection intensity at two tidal flats on Yeongheungdo Island in the west. Histology indicated that gametogenesis initiated in early spring, peaked in late spring to early summer, and was followed by spawning during summer. The CI increased prior to spawning and declined during autumn and winter, reflecting reproductive effort and food availability. Histology also revealed that heavy infection by the flatworm Cercaria tapidis leads to gonad castration during the spawning period. Trematode infection exhibited moderate seasonal variation but did not mask reproductive patterns. P. olseni infection intensity, measured by gill assays, displayed a significant spatial variation, as the intensity was significantly higher at Naeri tidal flat (p < 0.05), although P. olseni infection showed no significant correlation with CI or gonad maturation at either site. These findings suggest that, under the natural environmental conditions observed, P. olseni infection did not exert measurable adverse effects on the condition or reproductive development of the clams. This study emphasizes the substantial impact of seasonal environmental factors on the reproductive cycles of R. philippinarum, while suggesting that P. olseni infections may not directly affect reproductive performance at the observed infection levels.
To investigate the growth characteristics of the Cardiidae Keenocardium buelowi naturally inhabiting the coastal waters near Yokjido, a total of seven sampling surveys were conducted using a dredge net from May 2024 to January 2025. During the summer, a strong thermocline was observed. However, by November, the thermocline had broken down, resulting in a uniform water temperature of around 21°C throughout the water column, which led to an increase in bottom water temperature. Consequently, a notable decline in the distribution density of younger individuals was observed in December. Among the condition indices, the fatness index was found to reflect the condition of the population more sensitively. Growth curve analysis indicated that the theoretical maximum shell length (L∞) was 75.005 mm, the growth coefficient (K) was 0.363/year, and the theoretical age at zero shell length (t0) was 0.09394 years. The theoretical maximum total weight (W∞) was estimated at 104.38 g. The expected lifespan of the species was assessed to be approximately 6.54 years.
In this study, by analyzing the shape, type, impact radius, and microbiological effect of terrestrial pollutants around the Kamak Bay area, we tried to contribute to securing the microbiological safety of shellfish. The pollutants in the sea area around Kamak Bay were investigated as 340 places, and the total number of pollutants with flow generation was investigated as 49 places. Among them, nine points (P1-P9) where the concentration of fecal coliform was high and the flow rate was continuously generated were selected as the main land pollution source. As a result of the analysis, the concentration of fecal coliform was intermittently high at P1, P2, P4, P7, and P9, and the impact radius was about 1.5 km or more. As a result of analyzing the microbial pollution level of seawater and oysters in the Kamak Bay area, the fecal coliform pollution level of seawater was analyzed as < 1.8-49 MPN/100 mL, and the geometric mean and 90th percentile were analyzed as < 1.8-2.0 and < 1.8-4.0 MPN/100 mL, respectively. In addition, the fecal coliform, E. coli, and bacterial water pollution levels of oysters were analyzed as < 18-330, < 18-230 MPN/100 g, and 10-3,600 CFU/g. Taken together, major land pollutants flowing into the Kamak Bay area showed intermittently high levels of fecal coliform contamination. However, as a result of experiments on the microbial contamination of Kamak Bay seawater and oysters, it was determined that microbiological safety was secured by meeting all the hygiene standards of seawater and shellfish in Korea, the US sea area management standards for seawater, and the EU safety standards for shellfish. However, points P1, P3, P4, and P7 are considered to require periodic management as the affected radius is confirmed to be more than about 1.5 km due to large flow rates such as rainy weather.
In this study, we evaluated the impact of inland pollution sources on the sanitary status of seawater and shellfish (Short neck Clam) in the Narodo Area after 33.0 mm and 116.1 mm rainfall events. We analyzed the sanitary indicator microorganism such as coliform group, fecal coliform, Escherichia coli (E. coli) and Male-specific coliphage (MSC) in the discharge waters from the waste water treatment plants (WWTPs) and major inland pollution sources and also in seawater and shellfish for 3 or 4 days after 33.0 mm and 116.1mm rainfall events to determine how rainfall events increase the adverse impact of inland pollution sources on shellfish growing area . In the discharges from WWTPs, the range of coliform group and fecal coliform was 13-17,000 and 11-1,300 MPN/100 mL after 33.0 mm rainfall and was 490-35,000 and 330-13,000 MPN/100 mL after 116.1 mm rainfall events. Also, the range of fecal coliform and the radius of calculated impacted area of 5 major inland pollution sources contaminants was from 7.8 to 130,000 MPN/100 mL and from 4 to 960 m after 33.0mm rainfall and was from 79 to 540,000 MPN/100 mL and from 10 to 1,100 m after 116.1 mm rainfall events. The fecal coliform of seawaters from 16 stations in the designated area and 15 stations in the adjacent area ranged from < 1.8 to 17 and from < 1.8 to 14 MPN/100 mL, respectively. The E. coli level of shellfish at 4 stations in the designated area ranged from < 18 to 230 MPN/100 g.
This study assessed the impact of inland pollution sources on the sanitary status of seawater and shellfish (Abalone) in the Bogil-Nohwa Area after rainfall events of 16.0 and 55.7 mm rainfall events. We analyzed sanitary indicator microorganisms including coliform group, fecal coliform and Escherichia coli (E. coli) in the discharge water from major inland pollution sources, seawater and shellfish for 4 days after rainfall events. After the 16.0 mm rainfall, coliform group and fecal coliform concentrations in the discharge water from 5 domestic wastewater sources increased, reaching a range from 49,000 to 230,000,000 MPN/100 ml and from 4,600 to 130,000,000 MPN/100 ml, respectively. The radius of the impacted area ranged from 173.6 to 2,208.7 m. After the 55.7 mm rainfall, coliform group and fecal coliform concentrations ranged from 11,000 to 24,000,000 MPN/100 ml and from 78 to 3,300,000 MPN/100 ml, with the radius of the impacted area ranging from 97.8 to 1,079.8 m. The fecal coliform levels in seawaters at 33 stations ranged from < 1.8 to 79 MPN/100 ml and the E. coli levels in shellfish at 4 stations ranged from < 18 to 130 MPN/100 g. Salmonella spp. was not detected in any shellfish samples.
Crassostrea gigas is a sessile bivalve commonly found in intertidal and subtidal zones. Due to its high environmental adaptability and rapid growth, it has become a commercially important aquaculture species worldwide, particularly in Asia. In South Korea, oyster farming is a major sector of marine aquaculture, with a production volume of approximately 267,000 tons in 2021. However, concerns over potential inbreeding depression caused by long-term monoculture practices highlight the need to maintain genetic diversity in cultured populations. This study aimed to assess the genetic diversity and population structure of C. gigas in South Korea by using 16 microsatellite markers. A total of 288 individuals were sampled from six locations: Ganwoldo (Taean), Iwon-myeon (Taean), Jindo, Shinan, Gunsan, and Tongyeong. The number of alleles per locus ranged from 4 to 27, with an average of 10. The observed and expected heterozygosity values were 0.541 and 0.592, respectively, indicating a relatively high level of genetic diversity in the populations analyzed. Analyses of genetic distance, pairwise FST values, UPGMA clustering, and principal component analysis (PCA) revealed little genetic differentiation among the Ganwoldo (Taean), Iwon-myeon (Taean), Jindo, Shinan, and Gunsan populations. However, the Tongyeong population exhibited a low but statistically significant genetic divergence (p < 0.05). These findings provide a valuable genetic baseline for the conservation, evaluation, and sustainable management of C. gigas resources in South Korea.
