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Sea ice breakup and nutrient supply regulate the timing and magnitude of algal export over the slopes of the Pacific Arctic region
No full textFew in situ measurements are conducted early in the productive season in the Arctic Ocean, making it difficult to accurately assess the impact of the recent decline in sea ice cover on algal fluxes. Since 2017, time-series sediment traps have been deployed to collect sinking particles at two sites in the Pacific Arctic region. Here, we present algal fluxes obtained in the East Siberian Sea (ESS) and in the northern Chukchi Sea (NCS) between August 2017 and November 2022. Despite interruptions in sampling, algal fluxes reflected large spatial and temporal variations in the magnitude and timing of algal blooms and export in the region. In the ESS, peak diatom fluxes > 600 million cells m−2 d−1 in early August 2018 reflected the occurrence of an unusually large and long-lasting diatom bloom sustained by an episodic inflow of nutrient-rich waters. Diatom fluxes were usually lower in the NCS than in the ESS, reaching a peak flux of > 170 million cells m−2 d−1 in late August 2017. As diatoms consistently contributed to the majority of algal fluxes, their rapid decrease and near absence frequently observed during July or August at both sites reflected low nutrient concentrations in the upper water column leading to a dominance of small algal cells typically retained in upper waters. Overall, whereas nutrient supply influenced the magnitude and duration of the diatom fluxes, sea ice breakup determined the timing of peak diatom export in the Pacific Arctic slope region.11Nsciescopu
Thalassobellus sediminis sp. nov. and Thalassobellus citreus sp. nov., isolated from tidal flat sediment
No full textTwo Gram-stain-negative, facultatively anaerobic, rod-shaped (1.1–2.1 μm × 0.3–0.6 μm) and non-motile marine bacteria, designated as MEBiC06508T and MEBiC06459T, were isolated from tidal flat sediments in Taean City and Ansan City, respectively, on west coast of Korea. The 16S rRNA gene sequence analysis revealed that the two novel strains were affiliated to the genus Thalassobellus, a member of the Flavobacteriaceae, showing 97.0–98.4% sequence similarity with the type strain of Thalassobellus suaedae. Strains MEBiC 06508T and MEBiC06459T grew optimally at 25°C (15–35°C) and 22°C (12–30°C), at pH 7 (pH 6.5–8.0 for both strains), and 2–3% (1–5%) NaCl concentration, respectively. The major cellular fatty acids of both strains were iso-C15:0, iso-C15:1 G, iso-C15:0 3-OH and iso-C17:0 3-OH, similar to the type strain of Thalassobellus suaedae, while strains MEBiC06508T and MEBiC06459T contained higher proportion of C17:1ω6c and C18:3ω6c, respectively, compared to other strains. Both strains showed similar DNA G + C ratio (31.3–31.4 mol%) and fatty acids pattern compared to those of members in the genus Thalassobellus, however, differences between each other and other members in the enzyme activities and carbon sources utilization patterns. The genome contents showed that both strains encode numerous glucanase and pectinase genes and possibility to ferment sugar monomers. Based on the phenotypic taxonomicla data, strains MEBiC06508T and MEBiC 06459T should be identified as two novel species in the genus Thalassobellus, for which the names Thalassobellus sediminis sp. nov. (MEBiC06508T [=KCTC 92522T =JCM 37061T]), and Thalassobellus citreus sp. nov. (MEBiC06459T [=KCTC 102281T =JCM37060T]) are proposed.33Nscopuskc
Characteristics of meiofaunal communities inhabiting waters surrounding marine research stations based in the Yellow Sea and East China Sea
No full textThis study aimed to analyze meiofaunal communities near three marine research stations (MRSs) installed in the Yellow Sea to identify the characteristics of meiofaunal communities in subtidal zones. The study was conducted using samples collected near Ieodo MRS (I-MRS), Gageocho MRS (G-MRS), and Socheongcho MRS (S-MRS) located on the southern, central, and northern parts of the Yellow Sea, respectively. The average distribution density of meiofauna was 118.9 ± 11.1 Inds./10 cm2 in 2016 and 237.4 ± 33.7 Inds./10 cm2 in 2020 near I-MRS; 65.9 ± 12.5 Inds./10 cm2 in 2017 near G-MRS; and 196.9 ± 32.8 Inds./10 cm2 in 2018 and 392.5 ± 41.8 Inds./10 cm2 in 2019 near S-MRS. The range of these abundances is similar to those observed in the subtidal zones of the Yellow Sea. The results showed that the distribution density of meiofauna was high near the S-MRS but low near the G-MRS, which had fine-grained sediments and higher TOC content than the other MRSs. The mean number of meiofaunal taxa observed was 6.9 in 2016 and 8.9 in 2020 near I-MRS; 5.4 in 2017 near G-MRS; 8.8 in 2018 and 9.5 in 2019 near S-MRS. The G-MRS region, characterized by fine sediment, had the highest proportion of nematodes, the lowest abundance of harpacticoids among all MRS regions. Also the analysis of meiofaunal abundance by size revealed that there are higher and lower proportions of small-sized and large-sized meiofaunal individuals than the other MRS areas. A cluster analysis confirmed that the meiofaunal communities form distinct groups based on the locations of the MRSs. Correlation analysis between sediment environmental factors and distribution density of meiofauna revealed a significant negative correlation between sediment grain size and TOC content.11Nsciescopu
A green infrastructure planning approach for enhanced flood control and resilience in urban areas
No full textUrban flooding presents a growing challenge in metropolitan areas due to climate change and increasing impervious surfaces. This research proposes a Green Infrastructure (GI) planning approach to enhance flood control and resilience in the flood-prone Yeoksam-dong region of Gangnam, Seoul, South Korea. A mixed-method approach was employed, incorporating both residents’ preferences and hydrological simulations using the Stormwater Management Model (SWMM) to assess the effectiveness of various GI controls. Key GI co-benefits were identified through importance–performance analysis (IPA) and fuzzy weight rankings. Based on these, three GI scenarios were developed and evaluated for their flood mitigation potential. Scenario 1 (infiltration trench, rain garden, and rain barrel) emerged as the most effective, reducing surface runoff by 18.56 % and achieving the best cost-benefit ratio of 1.01 over a 10-year period. Scenario 2 (bio-retention, pervious pavement, and green roof), while less effective in terms of flood mitigation, may still offer ecological and social co-benefits. The study also conducted a sensitivity analysis, which confirmed Scenario 1’s robustness across various levels of imperviousness, making it a highly adaptable solution for urban settings. This research highlights the importance of community engagement in GI planning and demonstrates how integrating hydrological performance with socioeconomic benefits can enhance urban resilience. By aligning with the 4Rs of resilience; robustness, redundancy, resourcefulness, and rapidity, this study provides actionable insights for policymakers and urban planners seeking cost-effective, scalable solutions for flood-prone areas. The findings underscore the value of multifunctional GI controls in not only reducing flood risks but also promoting long-term sustainability and community well-being.11Nssciscopu
A Novel Method for Eliminating Glint in Water-Leaving Radiance from UAV Multispectral Imagery
No full textUnmanned Aerial Vehicle (UAV) high-resolution remote sensing imagery has been used for unprecedented coastal environment monitoring with ground sampling distance and time intervals of a few centimeters and seconds, respectively. However, high spatial-time resolutions of UAV remote sensing data consist of unexpected signals from water surface level changes induced by wind-driven currents and waves. This leads to non-linear and non-stationary forms of sun and sky glints in the UAV sea surface image. Consequently, these surface glints interfere with the detection of water body reflections and objects, reducing the accuracy and usability of the measurements. This study employed Fast and Adaptive Multidimensional Empirical Mode Decomposition (FA-MEMD) to separate the spatial periodicity of time-continuous multispectral images of the sea surface from the original data and retain non-oscillatory signals called residual images. The residual images effectively represented the spatial-temporal radiance and flow variations in the water body by correcting the regions of surface glint. This study presents three key findings: First, homogeneous surface radiance data with surface glint removed from the raw image sequence was acquired using FA-MEMD. Second, the continuous surface glint removal effect is validated through water-leaving radiance (Lw-SBA) measurements obtained via the Skylight-Blocked Approach (SBA) method. Comparisons showed that R2 values for the data obtained from clear water before and after surface glint removal were 0.02 and 0.56 with RMSE values of 8.37 x 10-5 and 5.51 x 10-5 Wm-2sr-1, respectively, indicating an improvement rate of 34.19%. Third, a comparative analysis with previous study methods demonstrated that our approach yielded spatially and temporally uniform homogeneous surface radiance data with less variability than traditional methods. The spatially and temporally synchronized residual images and the Lw-SBA data showed high similarity, confirming that the FA-MEMD technique effectively removed the surface glint from wave-induced roughness, enhancing the reliability of high-resolution UAV sea color observations.11Ysciescopu
Ongoing South China Sea Dispute: Is it Permitted for Continental States to Establish an Archipelagic Regime in their Outlying Archipelagos?
No full textThis article explores the controversies between the United States (US) and China regarding the renewed attention given to China’s claims for an archipelagic regime encompassing four groups of islands in the South China Sea, following the 2016 arbitral award. It examines whether continental States, rather than archipelagic States, can establish straight baselines enclosing their outlying archipelagos in light of the United Nations Convention on the Law of the Sea (UNCLOS) and contemporary State practice. Following the 2016 South China Sea award, this issue became a key point of sharp debate between the US and China, particularly regarding China’s attempts to justify its claims to maritime jurisdiction within the nine-dash line. Although the claims of continental States for an archipelagic regime were not accepted during the Third United Nations Conference on the Law of the Sea, it cannot be definitively concluded that the practice of continental States establishing straight baselines around their outlying archipelagos is entirely precluded from evolving into customary international law. However, considering current State practice, it is difficult to argue that the recognition of an archipelagic regime for outlying archipelagos by continental States has met the requirements for the formation of a part of customary international law.33Nscopuskc
Treatment system and methods for the wastes originated from seaweed and marine life followed by the used thalassotherapy resources
No full text- 기존 관련 폐기물 처리시설들은 주로 육상 기반 처리시설로서 염분이 있을 경우, 반응기 및 배관 부식
등 문제가 발생할 수 있으며, 장치의 크기가 매우 크므로 이동, 재배치, 재설치 등이 곤란함.
- 현재 관련 폐기물 처리시설들은 주로 건조(Drying),열분해(Thermal decomposition), 소각
(Incineration) 등 처리 기작과 장치가 있지만, 해양 치유자원 사용 후 발생하는 해조류 또는 해양생물 폐
기물의 처리, 처리 산물의 재활용 및 처분에 그대로 적용할 수 없음.
- 현재 우리나라에 해조류 또는 해양생물 폐기물과 이러한 폐기물에 함유된 오염물질과 염분을 처리할 수
있는 처리기술 또는 처리시설은 없으므로, 새로운 개념의 처리기술을 개발하거나, 처리시설을 조성하여야
함
Long-term impacts of heavy metal contamination in the East Sea-Byeong ocean dumping site, Republic of Korea
No full textThis study analyzed sediment samples from the East Sea-Byeong ocean dumping site in the Republic of Korea during three key years: during active ocean dumping (2009), just before the sewage sludge dumping ban (2015), and six years post-ban (2022). The study established regional background concentrations and contamination levels of eight heavy metals (Cr, Ni, Cu, Zn, As, Cd, Pb, and Hg). The results indicate a general reduction in contamination levels following regulatory measures and natural recovery processes. However, past dumping activities have a persistent influence on several indicators. In 2022, geo-accumulation index (Igeo) values for Hg, Cd, Pb, and Cr remain high, and the Pollution Load Index (PLI) also exceeds 1. Additionally, consistent patterns observed in Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) further underscore this ongoing impact. This study underscores the need for long-term monitoring to track recovery, evaluate regulatory effectiveness, and support decisions for sustainable environmental management and ecosystem restoration.11Nsciescopu
Copepods (Crustacea) of Family Lamippidae Parasitic in Octocorals (Cnidaria) from Korea
No full textOne new genus and 10 new species of the family Lamippidae are described as parasites of octocorallian corals from Korean waters. The newly described taxa include Gudogius pelagicus n. gen. n. sp., Lamippella merista n.
sp., Lamippella bulbosa n. sp., Lamippula radicata n. sp., Lamippula bisetata n. sp., Lamippula bifurcata n. sp., Enalcyonium granulatum n. sp., E. lobiferum n. sp., E. paraciliatum n. sp., and E. littorale n. sp. Gudogius n. gen., a primitive lamippid genus parasitic on the pennatuloid Balticina willemoesi (Kölliker, 1880), is characterized by the four-segmented antenna, the well-developed maxilla, the two-segmented female maxilliped, uniramous legs 1-4, and the well-developed male maxilliped. Enalcyonium digitigerum Ho, 1984 is redescribed based on newly collected Korean material. The acicule and digitation (digitiform seta) of caudal rami, which have previously been considered important taxonomic characters in defining genera of the Lamippidae, are reconsidered for their taxonomic value, since the acicule is found to be a sporadic outgrowth discharged from inside the body rather than a consistent morphological entity and the digitation may originate from a normal seta by cutting off its distal part within a lamippid individual.22Nkc