Photodegradation of PET plastics produces persistent compounds that accumulate in sediments.

Polyethylene terephthalate (PET) is one of the most widely used plastics, particularly in packaging and textiles. Although PET is widely used in consumer products, only 10-28 % is recycled. Most PET waste is not properly managed.

Source-specific contamination process revealed by mercury isotope analyses and hydrodynamic modeling in an estuary.

While mercury (Hg) concentration and isotope analyses play pivotal roles in understanding contamination levels and Hg sources, complex hydrodynamics often obscure Hg transport pathways from source to sink. We applied hydrodynamic modeling with Hg stable isotopes to unravel source-specific contamination processes and propose effective management strategies in an estuarine system (Yeongil Bay) impacted by Hg-contaminated riverine input (Hyeongsan River) in Korea. Sediment isotope data revealed contributions of three sources: legacy Hg from the river, regional background Hg, and atmospheric Hg sources.

Combined effects of hypoxia and thermal stress on hemocyte response in Pacific oysters (Crassostrea gigas): Insights from transcriptomic and proteomic analyses.

Hypoxia and elevated seawater temperatures are increasingly prevalent stressors in marine ecosystems, significantly impacting the physiology of marine organisms. This study investigates the transcriptomic and proteomic responses of Pacific oyster (Crassostrea gigas) hemocytes to hypoxia alone (water temperature, 23 °C; dissolved oxygen [DO] level, 1 mg O₂/L) and combined hypoxia with high temperature (water temperature, 28 °C; DO level, 1 mg O₂/L) over a 10-day exposure period. Using RNA sequencing and liquid chromatography-mass spectrometry, we identified distinct molecular responses to these stressors.

Contrasting seasonal variability of net community production between the Southern Yellow Sea and the Northern East China Sea during spring and summer.

The Yellow Sea (YS) and the East China Sea (ECS), which comprise continental shelves with depths of 200 m or less, are recognized as some of the most productive coastal areas globally. Although this high productivity can contribute to carbon sequestration, the spatiotemporal variability of the biological pump remains unclear. To investigate this variability, net community production (NCP) in August 2020 was estimated based on high-resolution O/Ar measurements.

Complementary integrated assessment of zooplankton abundance, size structure, and biomass using hydroacoustic and stratified sampling methods.

Accurate estimation of zooplankton biomass remains challenging due to species-specific acoustic signatures and sampling biases. This study evaluated zooplankton abundance and biomass across acoustically defined layers and assessed the consistency between biomass estimates derived from net sampling and acoustic methods. Zooplankton samples were collected using the Multiple Opening/Closing Net and Environmental Sampling System (MOCNESS) in higher signal scattering layers (HSLs) and lower signal scattering layers (LSLs), with acoustic signals verified using a scientific echosounder (38 and 200 kHz).

Species-specific toxic responses of marine phytoplankton to metals leached from cobalt-rich ferromanganese crusts.

Cobalt-rich ferromanganese (Fe-Mn) crusts are minerals distributed on the slope of a seabed mountain from a depth of 400 to 7000 m. These crusts are considered a next-generation deep-sea mineral resource with abundant industrially useful metals and rare earth elements. However, the ecological impact of deep-sea mining activity on the marine ecosystem has not been fully elucidated.

Microplastic aggregation and sinking regulated by harmful alga Chattonella marina: Implications for vertical transport and resuspension.

Microplastics (MPs) are widespread pollutants in marine environments, with their vertical distribution strongly influenced by biological interactions such as aggregation with phytoplankton. This study experimentally examined the effects of the harmful algal bloom (HAB) species Chattonella marina (Raphidophyceae) on the aggregation, sinking, and resuspension of polyethylene (PE) and polypropylene (PP) MPs. Aggregate formation, MP sinking velocity, and sinking ratio were evaluated over a 92-day period, and the resuspension of settled aggregates was subsequently examined under low-temperature (12 °C) conditions.

Host niche partitioning and coexistence in and parasitoids infecting dinoflagellates.

Although much attention has been paid to defining the ecological niches of phytoplankton, those of marine parasites and/or parasitoids remain unclear. In this study, we aimed to define the ecological niches of and parasitoids infecting dinoflagellates. By performing high-frequency (i.

Seasonal variations of lipophilic marine toxins in phytoplankton and shellfish and identification of potential causative microalgae in the southern coast of Korea.

Lipophilic marine toxins (LMTs), including pectenotoxins (PTXs) and yessotoxins (YTXs), are emerging contaminants in Korean coastal waters. This study investigated the seasonal patterns, spatial distribution, and potential microalgal producers of LMTs in phytoplankton, wild mussels, and commercial shellfish collected along the southern coast of Korea in 2023. PTX2 was predominant in phytoplankton during early spring, while homo-YTX (hYTX) became dominant from late spring to summer.

N-terminal helix formation and dimer-monomer transition of FGF10 in specific recognition of FGFR2b.

Fibroblast growth factors (FGFs) are crucial for various cellular functions, including proliferation, differentiation, tissue repair, and immune responses. FGF10, part of the FGF7 subfamily, binds to the FGFR2b receptor via heparin sulfate. We determined the crystal structure of human FGF10 alone.

Identification of Novel Antimicrobial 2‑(Pyrimidin-2-yl)-5-alkyl-pyridazin-3(2)‑one Scaffolds against , Inspired by Luffariellolide.

Luffariellolide () was previously isolated in useful quantities (>200 mg) from the marine sponge sp., collected from the Philippines. The intrinsic antibacterial activity of was insignificant; however, 2-(pyridinyl)-pyridazinone , derived from , exhibited considerable activity against .

Effects of hull cleaning wastewater on coastal plankton community: A mesocosm experiment.

In-water hull cleaning, widely used to manage biofouling on ship hulls, releases wastewater (HCW) that contains high levels of heavy metals and suspended solids. These contaminants can directly alter water chemistry and disrupt planktonic community dynamics, yet their ecological effects in coastal environments remain poorly understood. In this study, a mesocosm experiment was conducted to evaluate the effects of increasing HCW concentrations (1 %, 5 %, and 10 %) on coastal marine planktonic ecosystems, including phytoplankton, zooplankton, and periphyton.

Temperature-Driven Intraspecific Diversity in Paralytic Shellfish Toxin Profiles of the Dinoflagellate Alexandrium pacificum and Intragenic Variation in the Saxitoxin Biosynthetic Gene, sxtA4.

Alexandrium pacificum, a globally distributed dinoflagellate, is well-known for causing harmful algal blooms and producing Paralytic Shellfish Toxins (PSTs), a threat to marine life and human health. The frequency and intensity of Alexandrium blooms have increased in recent decades, driven, in some cases, by increasing temperatures. Here, we investigated the temperature-dependent (15 °C, 20 °C, 25 °C, and 30 °C) growth rates and paralytic shellfish toxin profiles of eight A.

Annual distribution and deposition of atmospheric Pb in Busan, the largest port city in Korea.

This study examined the annual and seasonal variations of Pb in aerosols collected in Busan, a major port city in South Korea. Aerosol samples were obtained during two sampling campaigns: (i) total suspended particles (TSP) from April 2019 to February 2020, and (ii) particulate matter with diameters ≤10 μm (PM) and ≤2.5 μm (PM) from March 2020 to February 2021.

Seasonal and interannual variations in material transport in the Korea Strait originating from the Taiwan Strait.

Understanding the variability in material transport from the Taiwan Strait (TS) to the Korean Strait (KS) is crucial for predicting ecological changes and the spread of marine debris in the East Asian Marginal Seas (EAMS). However, the dynamic variability of this transport remains poorly understood. In this study, we investigated the dynamic variability of material transport from the TS to the KS, using a Lagrangian particle-tracking system coupled with a three-dimensional numerical model.

Magnetic Data Correction for Fluxgate Magnetometers on a Paramagnetic Unmanned Surface Vehicle: A Comparative Analysis in Marine Surveys.

Unmanned Surface Vehicle (USV) offers a cost-effective platform for high-resolution marine magnetic surveys using shipborne fluxgate magnetometers. However, platform-induced magnetic interference and electromagnetic interference (EMI) can degrade data quality, even with paramagnetic hulls. This study evaluates fluxgate magnetometer data acquired from a paramagnetic-hulled USV.

Prototype ultrasonic desalination instrument and its performance test.

A large-scale ultrasonic washing instrument was developed, and its performance was evaluated using an ultrasonic instrument and mechanical washing for desalination in sea sand. Preliminary experiments with a portable ultrasonic device confirmed that increasing the ultrasonic power intensity and application time increased effectiveness of salt washing in sea sand. On the basis of these findings, a large-scale washing instrument with a maximum output of 1500 W, an ultrasonic frequency of 28 kHz, and a 25 L capacity washing tank was developed.

Seasonal Dynamics of Algal Communities and Key Environmental Drivers in the Subpolar Front Zone off Eastern Korea.

Located within the subpolar front (SPF) zone, the eastern coast of Korea is subject to frequent environmental changes on both spatial and temporal scales. In this study, we analyzed seasonal changes in the algal community structure and related environmental factors at two sites, Chodo (CD) and Sageunjin (SG), which were influenced by cold and warm-water masses, respectively, in the SPF zone. Sea surface temperature (SST) exhibited greater seasonal change in CD, whereas significant wave height was higher in SG.

Robust daily satellite sea surface salinity reconstruction using deep learning in low-salinity coastal regions.

Spatiotemporally continuous sea surface salinity (SSS) is essential for monitoring rapid changes in the physical and biogeochemical characteristics of oceans and plays a crucial role in effective coastal environment management. Traditional physics-based SSS methods often oversmoothed salinity variations and struggle to capture sharp gradients, leading to reduced accuracy in river-dominated areas. In addition, the long revisit times of satellite data limit real-time monitoring.

Spatial variability of sediment geochemistry and meiofaunal communities in hydrothermal vent fields along the Central Indian ridge.

This study investigates the geochemical composition and meiofaunal communities in deep-sea hydrothermal vent sediments along the Central Indian Ridge (CIR). Our analysis focused on five vent fields: Onnuri, Onnare, Onbada, Invent E, and Kairei. Sediment analysis revealed spatial variation in heavy metal concentrations, with Onnare and Onbada exhibiting particularly high levels of As, Cd, Pb, Hg, Cu, and Zn.

Effect-directed analysis of hazardous organic chemicals released from ship hull hydroblasting effluents and their emission to marine environments.

Hydroblasting of ship hulls is a significant source of chemical emissions into marine environments, releasing a complex mixture of paint-derived constituents including biocides, pigments, polymeric binders, plasticizers, light stabilizers, and compounds from adhesives and sealants. Although the International Convention on Antifouling Systems highlights the importance of waste management, many countries, including South Korea, have not yet implemented specific regulations addressing hydroblasting effluents. Most existing studies have focused on target biocides, leaving other toxic chemical classes underexplored.

A comprehensive analysis of the scrapping and abandonment of fiber-reinforced polymer vessels at sea.

Fiber-reinforced polymer (FRP), also known as fiberglass, is a widely used composite material in marine, transportation, and construction industries because of its high strength, lightweight properties, and corrosion resistance. While FRPs are advantageous for these applications, the disposal and recycling of FRPs, especially in boats, remain challenging. The global FRP market valued at $3.

Isotope tracking of anthropogenic Cu and Zn in urbanized coastal environments: A review.

Copper (Cu) and zinc (Zn) are common trace metal contaminants in marine environments that, despite their importance for the health of marine organisms, can be toxic. Recently, the stable isotopes of these elements have emerged as powerful tracers for studying their cycles. Thus, this review aims to connect urban and marine interfaces under a "land-sea continuum" framework to understand the complex sources, pathways, and transformations of Cu and Zn in urbanized coastal environments, a perspective currently lacking in the literature.

A report of the huge and complex burrow system of the gebiidean mud shrimp Laomedia sp. (Crustacea: Laomediidae) in Korean intertidals.

We introduce an account of the unique burrow systems of Laomedia sp. and compare their structures between the environmentally distinct Saemangeum and Gomso tidal flats. Laomedia sp.

Characterization of known and unknown AhR-active substances in freshwater fish from the Gapcheon River, South Korea: Application of effect-directed analysis and nontarget screening.

This study investigated the distribution and composition of persistent toxic substances in freshwater fish collected from the Gapcheon River, Daejeon, South Korea. To identify key toxicants responsible for biological effects, effect-directed analysis was applied, focusing on aryl hydrocarbon receptor (AhR) agonists. The target species included crucian carp (S1, Carassius carassius), common carp (S2, Cyprinus carpio), Far Eastern catfish (S3, Silurus asotus), barbel steed (S4, Hemibarbus labeo), and skygager (S5, Erythroculter erythropterus).