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Thermomechanical Analysis of the Louisville Seamount Chain: Implications for Late Cretaceous Pacific Plate Evolution
No full textWe calculated elastic thickness (Te), flexural deflection, and gravity anomalies of the oceanic lithosphere beneath 14 seamounts of the Louisville Seamount Chain to investigate seamount formation timing and tectonic settings. Using dense core modeling to approximate seamount mass, we compared Te estimates with plate age at loading time. The northwestern seamounts (Te = 6–8 km) formed over the Louisville hotspot earlier than age-dated volcanism, consistent with Osbourn Trough tectonic motion. The middle seamounts (Te = 18–28 km) formed on lithosphere with consistent thermal age of 45 Myrs at loading time. The southeastern seamounts (Te = 4–12 km) formed on lithosphere with similar thermal age, with elastic thickness reduced by additional thermal stress from juxtaposed younger lithosphere across fracture zones. This consistent loading age (∼45 Ma) across both middle and southeastern groups indicates limited Louisville hotspot motion during seamount formation. Based on our Te estimates and thermal age patterns, we determined that the oceanic lithosphere beneath the middle section was produced by Late Cretaceous spreading centers between 105 and 84 Ma, providing new constraints on Pacific plate reconstructions during the Cretaceous Normal Superchron when traditional magnetic anomaly dating methods are limited.11Nsciescopu
Reconstruction Modeling and Validation of Brown Croaker (Miichthys miiuy) Vocalizations Using Wavelet-Based Inversion and Deep Learning
No full textFish species’ biological vocalizations serve as essential acoustic signatures for passive acoustic monitoring (PAM) and ecological assessments. However, limited availability of high-quality acoustic recordings, particularly for region-specific species like the brown croaker (Miichthys miiuy), hampers data-driven bioacoustic methodology development. In this study, we present a framework for reconstructing brown croaker vocalizations by integrating fk14 wavelet synthesis, PSO-based parameter optimization (with an objective combining correlation and normalized MSE), and deep learning-based validation. Sensitivity analysis using a normalized Bartlett processor identified delay and scale (length) as the most critical parameters, defining valid ranges that maintained waveform similarity above 98%. The reconstructed signals matched measured calls in both time and frequency domains, replicating single-pulse morphology, inter-pulse interval (IPI) distributions, and energy spectral density. Validation with a ResNet-18-based Siamese network produced near-unity cosine similarity (~0.9996) between measured and reconstructed signals. Statistical analyses (95% confidence intervals; residual errors) confirmed faithful preservation of SPL values and minor, biologically plausible IPI variations. Under noisy conditions, similarity decreased as SNR dropped, indicating that environmental noise affects reconstruction fidelity. These results demonstrate that the proposed framework can reliably generate acoustically realistic and morphologically consistent fish vocalizations, even under data-limited scenarios. The methodology holds promise for dataset augmentation, PAM applications, and species-specific call simulation. Future work will extend this framework by using reconstructed signals to train generative models (e.g., GANs, WaveNet), enabling scalable synthesis and supporting real-time adaptive modeling in field monitoring.11Ysciescopu
First reliable record of Parapercis decemfasciata (Labriformes, Pinguipedidae) (Franz, 1910) from Jeju-do Island, Korea
No full textA single specimen (108.12 mm standard length) of the family Pinguipedidae was collected using a Danish seine off Seogwipo-si, Jeju-do Island, Korea, on February 27, 2024. The specimen was identified as Parapercis decemfasciata (Franz, 1910), characterized by having 4 dorsal fin spines, yellow fins (except the pectoral fin when fresh), a continuous dorsal fin without a notch, 10 narrow transverse bands on the body, and 4 dark transverse bands on the caudal fin. This species closely resembles its congeneric counterpart, Parapercis multifasciata. However, they can be differentiated by the number of dorsal fin spines (4 in P. decemfasciata vs. 5 in Parapercis multifasciata), the presence of a black spot at the base of the caudal fin (absent vs. present), and the relative size of the snout and pupil (pupil larger vs. snout larger). Molecular analysis of 529 bp of mitochondrial DNA cytochrome c oxidase subunit I sequences showed that our specimen perfectly corresponded to those of P. decemfasciata from NCBI GenBank. Consequently, we believe this represents a reliable record of P. decemfasciata from Korea, and we propose adopting the Korean name “No-rang-yeol-dong-ga-ri” as suggested by Kim et al.33Yscopuskc
False Positive Patterns in UAV-Based Deep Learning Models for Coastal Debris Detection
No full textCoastal debris is a global environmental issue that requires systematic monitoring strategies based on reliable statistical data. Recent advances in remote sensing and deep learning-based object detection have enabled the development of efficient coastal debris monitoring systems. In this study, two state-of-the-art object detection models—RT-DETR and YOLOv10—were applied to UAV-acquired images for coastal debris detection. Their false positive characteristics were analyzed to provide guidance on model selection under different coastal environmental conditions. Quantitative evaluation using mean average precision ([email protected]) showed comparable performance between the two models (RT-DETR: 0.945, YOLOv10: 0.957). However, bounding box label accuracy revealed a significant gap, with RT-DETR achieving 80.18% and YOLOv10 only 53.74%. Class-specific analysis indicated that both models failed to detect Metal and Glass and showed low accuracy for fragmented debris, while buoy-type objects with high structural integrity (Styrofoam Buoy, Plastic Buoy) were consistently identified. Error analysis further revealed that RT-DETR tended to overgeneralize by misclassifying untrained objects as similar classes, whereas YOLOv10 exhibited pronounced intra-class confusion in fragment-type objects. These findings demonstrate that mAP alone is insufficient to evaluate model performance in real-world coastal monitoring. Instead, model assessment should account for training data balance, coastal environmental characteristics, and UAV imaging conditions. Future studies should incorporate diverse coastal environments and apply dataset augmentation to establish statistically robust and standardized monitoring protocols for coastal debris.11Ysciescopu
Spatial distribution of dissolved trace metals in the Nakdong River Estuary: Impact of an estuarine barrage on their chemical behaviors
No full text1
Spatial Variation of Energy Sourcing in Deep-Sea Vent Anemones from the Central Indian Ridge
No full textDeep-sea anemones from hydrothermal vents remain poorly understood in terms of their trophic strategies and chemosynthetic symbioses. In this study, we investigated the energy acquisition and trophic ecology of actiniarian species from five hydrothermal vent fields along the Central Indian Ridge (CIR), using bulk carbon (δ13C) and nitrogen (δ15N) stable isotope analyses, amino acid δ15N (δ15NAA), and 16S rRNA amplicon sequencing of symbiotic microbes. The anemones were identified as Alvinactis chessi, Alvinactis sp., and the unclassified Enthemonae. Isotopic data revealed significant spatial variation, indicating differing microbial carbon fixation pathways and trophic interactions. Elevated δ13C values of anemones at Mirae-2, Cheoeum, and Kairei suggest a reliance on reductive tricarboxylic acid (rTCA) cycle-based primary production, whereas more 13C-depleted δ13C values at Onnare and Saero are consistent with the predominance of Calvin–Benson–Bassham (CBB) cycle-based carbon sources. The δ15NAA values confirmed varied nitrogen sources, with some anemones likely feeding on Bathymodiolus mussels, shrimps, or polychaetes depending on the availability of these organisms in the community. Notably, despite clear differences in symbiotic microbial community composition between Alvinactis spp. and co-occurring the unclassified Enthemonae, their isotopic signatures were similar, indicating shared dietary sources. These findings demonstrate that while anemones harbor distinct symbiotic microbial communities, their nutritional strategies are primarily shaped by local environmental conditions and prey availability rather than host species identity or symbiont community composition. This highlights the dietary flexibility of deep-sea anemones and underscores the central role of site-specific environmental conditions in structuring trophic interactions at hydrothermal vents.11Nsciescopuskc
폐쇄생태계에서 환경요인 변동이 해조류 성장에 미치는 영향과 핵심 인자 검증
No full text해조류는 연안 생태계의 주요 1차 생산자로서, 환경변화에 따른 성장 및 사멸 특성의 이해는 해양 생태계 관리를 위해 필수적이다. 본 연구는 폐쇄생태계에서 감태, 대황, 우뭇가사리를 대상으로 수온, 영양염, pH, 염분 등의 환경요인 변동이 해조류 성장과 생존율에 미치는 영향을 검증하고자 수행되었다. 연구는 세 단계로 진행되었으며, 1차년도에는 2010~2021년 해양환경관측망 자료를 활용해 경북 포항 구룡포부터 강원도 거진 연안까지 52개 정점의 수온, 염분, pH, 용존산소, DIN, DIP, WQI (Water Quality Index) 항목을 분석하고, 폐쇄생태계 실험 인프라를 구축하였다. 2·3차년도에는 폐쇄생태계를 활용하여 다양한 환경요인 조합(수온, 영양염, CO₂ 농도 등)에 따른 해조류 성장 특성을 평가하였다. 관측망 분석 결과, 동해안 갯녹음은 해수온 상승(특히 겨울철)과 용존무기질소 감소에 의한 영향으로 나타났으며, 집중 강우로 인한 저염분의 영향도 확인되었다. 해조류의 성장에 미치는 주요 환경요인을 검증하기 위해 실험을 수행한 결과 수온과 영양염 농도에 따라 크게 영향을 받았으며, 수온 15℃ 조건에서 가장 높은 성장률을 보였다. 반면 20℃ 조건에서는 광합성 효율이 저하되고 성장률도 낮았다. 영양염이 부족한 조건에서는 엽체 끝녹음이 관찰되었으며, 주입된 DIN과 DIP는 48시간 내 대부분 소모되었다. pH와 CO₂농도 구배를 통한 대황 실내실험에서는 CO₂ 농도에 따른 성장률 차이는 보이지 않았으며, 최대 12일까지 성장이 관찰되었다. 실외실험에서는 CO₂농도가 4배인 조건에서 뚜렷한 성장이 나타났으며, 수온은 13~18℃로 관찰되었다. 마지막으로 수온조건이 동일한 우뭇가사리 염분 배양실험 결과 저염분 실험구에서 성장 저해 및 끝녹음이 가속화되는 경향을 확인하였다. 본 연구는 폐쇄생태계 기반 실험을 통해 환경요인 변동이 해조류 성장과 생존에 미치는 영향을 확인하였으며 향 후 연구에서는 복합적인 환경요인 변동과 미세조류를 활용해 해조류와의 상호작용에 대한 연구를 진행하고자 한다.2
Annual Variability of Middle-Layer Water Temperature in the East Sea, Korea: Insights from Long-Term Observations (1995–2022)
No full textThe variability of middle-layer water temperatures in the East Sea of Korea is a critical indicator of oceanic and ecological changes, complementing the more widely studied surface temperature trends. While surface water temperatures have shown an annual increase of approximately 0.05℃/yr, this study focused on analyzing temperature variability at depths of 300 m, 400 m, and 500 m, where seasonal fluctuations are minimal. Using CTD data from 64 stations collected by the Korea Oceanographic Data Center between 1995 and 2022, the study revealed annual temperature increases of 0.0126℃/yr at 300 m, 0.0085℃/yr at 400 m, and 0.0093℃/yr at 500 m. Spatial analysis indicated that the south of Ulleungdo exhibited relatively high temperature variability, correlating with the formation zone of the Ulleung Warm Eddy, which plays a pivotal role in regional heat and material transport.
Significantly, the observed warming below 300 m depth—beneath the permanent thermocline—suggests that deep-sea regions, previously thought to exhibit minimal thermal variation, are increasingly affected. This warming trend has potential implications for deep-sea ecological dynamics, oxygen concentration, and biogeochemical processes. Furthermore, these changes align with global patterns of ocean warming driven by anthropogenic climate change.
To better understand the long-term impacts on the East Sea’s thermal structure and its ecosystem, it is essential to extend monitoring efforts to deeper layers below 500 m. Such observations will provide insights into the interplay between regional oceanographic phenomena, such as the Ulleung Warm Eddy, and broader climate change influences.1
Civil Liability for Marine Environmental Pollution Damage
No full textTransboundary environmental harm or damage has been a long-standing concern under international environmental law, with the issues of responsibility/liability and compensation frequently raised, particularly by developing countries. While much of the legal focus has been placed on states’ preventive obligations and responsibility, civil liability remains relatively underexplored. Nevertheless, civil liability is significant in that it can complement the limitations of state responsibility and serve both remedial and preventive functions. Among various types of transboundary environmental damage, civil liability is particularly relevant to marine environmental pollution damage and appears to hold the greatest potential for further normative development within the international legal order governing marine environmental protection. Accordingly, this article explores the potential for normative development of civil liability for marine environmental pollution damage within the regime of the United Nations Conventions on the Law of the Sea (UNCLOS). Rather than proposing a detailed treaty draft provisions, it aims to offer a normative framework of civil liability for damage caused by activities in the Area and geo-engineering based on an interpretive analysis of Article 235 of UNCLOS. This framework is intended to provide conceptual guidance for future discussions on liability and compensation in international law. Modelled on the existing regime for oil pollution damage, the proposed framework suggests that contractors or operators should bear strict liability for significant marine environmental pollution damage. In addition, they are expected to be held jointly and severally liable for such damage; have an exhaustive list of defenses against such liability; benefit from limitations on compensation in terms of amount and time; have and maintain insurance or other form of financial security; and be supplemented by compensation funds if their compensation is insufficient.22Nkc
Secondary Metabolites from the Sponge Stellitethya ingens. Isolation, Structure Elucidation, and TRPA1 Inhibitroy Activity.
No full textTransient Receptor Potential Ankyrin1 (TRPA1) is a non-selective cation channel involved in pain and inflammation, making it a promising therapeutic target for treating related diseases. In this study, we investigated the marine sponge Stellitethya ingens, as its crude extract showed inhibitory activity against human TRPA1 (76.9% inhibition at 10 μg/mL). Chemical investigation led to the isolation of thirteen nitrogen-containing sesquiterpenoids (1–13) and eight glycerophospholipid analogues (14–21), including four previously unreported bisabolene-type analogues (3 and 6–8) and one novel phosphatidylcholine derivative (21). Their structures were elucidated using 1D/2D NMR, HR-ESIMS, and MS/MS analyses, with stereochemistry confirmed by NOESY correlations, pyridine-induced deshielding effects, and asymmetric synthesis. The FLIPR calcium assay revealed that compounds 1 (the major constituent of the extract), 3, and 12 exhibited moderate inhibitory activity against TRPA1. These findings expand the chemical diversity of S. ingens and identify three TRPA1 antagonists, providing valuable insights for future structure-activity relationship studies.2