Characterization of Clastic and Organic Sediments Near Dokdo, Korea

With the aim to restore the colonies of four halophyte species (Salicornia europaea, Suaeda glauca, Suaeda japonica, and Suaeda maritima) that live in upper tidal flats, we performed sowing in the tidal flats of Daebudo Island in the West Sea by varying the altitude, sowing time, and sowing depth and measured the germination density, growth rate, and soil environment of the target sea area. We also investigated the growing conditions of large natural colonies of S. japonica formed around the area. The results indicated that altitude and mean grain size strongly influenced halophyte germination and growth. S. europaea, S..glauca, and S. maritima were influenced by altitude, and S. japonica by average grain size. For the same sowing time, germination density was higher for S. japonica and S. maritima without vernalization and S. europaea with vernalization. The more the sawing depth, the higher the germination density and growth of all species. Furthermore, the germination density of S. glauca was significantly lower than that of the other species, making it difficult to evaluate the influencing environmental factors. This is the first study to report germination experiments on tidal flats in Korea, and continuous research will be required to ensure that the halophytes are conserved as second nature by monitoring for environmental pressures and cultivation.

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Long-Term Monitoring of Macroinvertebrate Community Assemblages and Species Composition on the Coast of Dokdo, East Sea of Korea

Gwak,

Kim,

Lee

et al. 2024

Diversity

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Dokdo Island’s diverse marine ecosystem requires long-term monitoring to understand the effects of rapid environmental changes, such as global warming, on macrobenthos species and communities. Current studies are often short-term and limited, highlighting the need for extended research to predict future changes to ecosystems. This study analyzed the environmental variables influencing macrobenthos through long-term monitoring. In total, 511 species (spp./23.4 m2) were identified with an abundance of 1709.9 individuals/m2 and a diversity of 2.9. Since 2020, there has been a decline in both the number of species and diversity, attributed to changes in sediment composition, particularly an increase in gravel and sand. The dominant species include the crustacean Abludomelita denticulata (17.6%), the polychaete Haplosyllis spongiphila (6.8%), the bivalve Glycymeris munda (5.6%), the polychaete Opisthodonta uraga (5.3%), and the bivalve Limatula japonica (3.8%). The macrobenthos community differs each year, as the dominant species G. munda has decreased in abundance since 2022 and L. japonica since 2021. Depth and gravel sediment strongly correlated with community variation. Site-specific analysis also showed significant differences, with depth, bottom temperature, and sediment composition as the influencing factors. These species thrive in cold water but their abundance declines with an increase in temperature. Continuous long-term monitoring is essential to understand and protect the Dokdo ecosystem amid rapid environmental changes. Long-term monitoring studies have revealed more species than have short-term studies, showing annual and site-specific environmental changes, including sediment erosion and bottom temperature increases. These changes have affected macrobenthos diversity, abundance, and community composition, necessitating ongoing research to determine the persistence of these trends and to protect the ecosystem.

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Characterization of Clastic and Organic Sediments Near Dokdo, Korea

Cited by 4 publications

References 43 publications

Clay mineral characteristics in volcanic tuffs of Dokdo, South Korea: implication on their genesis and evolution

Clay mineral characteristics in volcanic tuffs of Dokdo, South Korea: implication on their genesis and evolution

Field experiments on the growth conditions of halophytes from Daebudo Tidal Flats, West Sea of Korea

Long-Term Monitoring of Macroinvertebrate Community Assemblages and Species Composition on the Coast of Dokdo, East Sea of Korea

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