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ISSN : 1225-3480
As one of endangered species, the habitat status of Cristaria plicata was studied in thriteen different streams inflowing into the Nakdong River. The distribution of C. plicata was confirmed in six streams (Yangsan Stream, Milyang River, Sangnam Stream, Hwapo Stream, Jucheon River and West Nakdong River), and was highly concentrated in the Milyang and Jucheon Rivers. The surveyed stream where the species was found were characterized by slow-moving or stagnant water and a muddy substrate. C. plicata was most frequently observed at water depths of 1.0 to 2.0 m (90.6%) and in mud depths of 10.0 to 30.0 cm (97.8%). Water quality factors appear to have a minimal impact on the habitat of C. plicata. However, in the case of DO, levels below the minimum concentration required for biological habitation (4.00 mg/L) can negatively affect growth and, in severe cases, lead to mortality.
Although Cristaria plicata is protected as an endangered species, ecological research on this species remains insufficient. This study conducted experiments on the mobility of C. plicata. The results of the movement distance measurement showed that the mobility was higher in sand area (300.2 cm) than in mud area (69.4 cm). The difference in mobility is considered to be due to differences in the physical environment and food availability. Sand area have large changes in the physical environment and an unstable distribution of food sources, so it is thought that movement occurs to increase survival stability. The average locomotion speed was found to be slow at 6.62 cm/hr. This means that it is highly likely to be easily exposed to survival risks such as rapid water level decline. Spearman rank correlation analysis between individual size and movement distance/speed showed no significant difference (P > 0.05). That means that individual size does not directly affect movement distance or locomotion speed. The results of this study can be used as important data for securing the survival stability of C. plicata and protecting and managing its habitat environment, and can be especially useful in determining the discharge amount and rate of dams, weirs, and reservoirs.
This study evaluates the hygienic safety of the HansanㆍGeojeman area based on hygiene indicator bacteria from seawater and shellfish samples collected between 2015 and 2023, by constructing the wastewater treatment plant and expansion of its service area. The geometric mean and 90th percentile values of fecal coliforms in seawater showed a significant reduction, from 2.5-6.5 MPN/100 mL to 2.1-3.7 MPN/100 mL (a decrease of 12.0-43.1%) and from 10.7-62.3 MPN/100 mL to 3.6-13.7 MPN/100 mL (a decrease of 44.9-78.0%), respectively. Additionally, the geometric mean of Escherichia coli in shellfish decreased from 25.0-26.5 MPN/100 mL to 19.0-20.6 MPN/100 mL, showing a decrease of 17.6-28.3%. Following the expansion of the wastewater treatment plant's service area, fecal coliform levels in Naegan stream decreased from 3.8 log MPN/100 mL to 2.1 log MPN/100 mL, and the affected range was reduced from 670 meters to 160 meters. These results showed that the importance of managing both land-based and marine pollution sources, including the expansion of wastewater treatment plant, to ensure the hygienic safety of shellfish
The spatio-temporal distribution of toxic phytoplankton was investigated in seven designated shellfish growing areas along the southern coast of Korea from April 2021 to March 2022. Vegetative cells of eight toxic phytoplankton species were monitored using the Utermöhl method, and additional environmental DNA analysis and resting cyst surveys were conducted at nine sampling stations in Hansan-Geojeman area (Designated Area No. 1). Results revealed that Pseudo-nitzschia spp. occurred most frequently in all areas, while Alexandrium spp., Dinophysis spp., and Prorocentrum cordatum were identified as the predominant toxic phytoplankton. In Hansan-Geojeman area, vegetative cells of Alexandrium spp. increased during February-March 2022, and environmental DNA analysis identified A. catenella and A. pacificum as the dominant species. A significant correlation was observed between the paralytic shellfish toxin-producing gene sxtA and A. catenella in the environmental DNA analysis, while resting cyst surveys demonstrated high occurrence frequencies at specific stations (stations 1 and 9). This study provides fundamental data for monitoring toxic phytoplankton in shellfish growing areas along the southern coast of Korea, validates the appropriateness of the existing monitoring stations, and suggests the necessity of additional monitoring stations.
Bivalvia is a globally significant seafood resource, and the increasing international trade due to Free Trade Agreements (FTAs) is expected to lead to the influx of various foreign species into the domestic market. This study was conducted to proactively address the potential threats that this increasing import trend may pose to the domestic marine ecosystem and market. We analyzed the import status of Bivalvia in Korea over the past five years and extensively surveyed relevant literature and databases to establish a list of 617 potentially imported foreign Bivalvia species. Furthermore, we aimed to prevent confusion in the import and distribution process and enhance consumers' right to know by establishing a standardized Korean naming system based on scientific names.The results of the study revealed that new Korean names were assigned to 296 species, and existing names were revised for 9 species, with the families Veneridae and Pectinidae being identified as major expected import species. This study is expected to contribute to providing scientific fundamental data for the systematic management of foreign Bivalvia and the sustainable development of the fisheries industry.
Aquaporins (AQP) are membrane proteins that regulate cellular water balance and are widely expressed in both animals and plants. AQP contributes to maintaining cellular water homeostasis and body fluid balance under various environmental conditions. This is essential for mollusks, and AQP is known to be important factors involved in this process. The genetic information of Koreoleptoxis nodifila, an endangered gastropod from Korea, is poor, and there is no report on AQP. In this study, we analyzed transcriptome data obtained using the Illumina HiSeq 2000 platform to identify the AQP gene in K. nodifila. The K. nodifila AQP gene contains a 1,056-bp open reading frame (ORF) encoding a protein consisting of 352 amino acids. Conserved domain analysis revealed that this protein has six alpha-helical transmembrane structures, which suggests that it is classified as a membrane protein. InterPro analysis confirmed that this protein belongs to the major intrinsic protein (MIP) superfamily. Multiple sequence alignment using ClustalX2 identified a conserved asparagine-proline-alanine (NPA) motif associated with water transport functions. Also, endangered K. nodifila is difficult to verify through molecular biological experiments; therefore, an in silico analysis was performed. The results confirmed that K. nodifila AQP belongs to the Pleuroceridae lineage and is positioned within Gastropoda. This study is the first to elucidate the AQP gene sequence of K. nodifila andis expected to be used as basic data for securing genetic resources and functional studies.
