Green tide events caused by Ulva prolifera have emerged as a significant ecological issue in the western coast of Yellow Sea. This study investigated the morphological and physiological changes of U. prolifera as it drifted from the initiation region (Subei Shoal) to the southern coastline of Shandong Peninsula. The goal was to elucidate the underlying mechanism of its adaptation and responses to the environmental variability along its drifting path. The results indicated that U. prolifera experienced a morphological shift from compact thalli with few branches to fragmented, densely branched forms during its northward migration, that enhance its surface area for nutrient uptake and light capture. Photosynthetic activity of lateral branches was significantly higher than that of the main blades, especially in the southern regions. Correlation analyses identified salinity and latitude as the most influential environmental variables, with lower salinity in the southern Yellow Sea facilitating the dense formation of branches. The strong correlations with nutrient availability also highlighted the role of resource availability in shaping the morphology of U. prolifera. Additionally, nitrogen content decreased along the drift path, contributing to an increase in the C/N ratio, which likely influenced the algal morphology and growth rate. These findings revealed that the morphological plasticity of U. prolifera plays a critical role in its ability to adapt to environmental gradients and supports its rapid bloom development. Our results highlight the importance of managing nutrient inputs, especially nitrogen, and suggest that controlling early fragmentation and improving aquaculture practices could mitigate green tide events.

The Deepwater Horizon (DWH) spill was one of history's largest oil spills. The marine-oil snow sedimentation and flocculation accumulation event, known as the MOSSFA event, occurred after the oil rig's blowout. Patterns in Gulf of Mexico benthic foraminiferal assemblages during the DWH spill were identified and their potential use as indicators of past oil spills was investigated. Wall composition, assemblage composition and species diversity were analyzed and compared to levels of dark particulate matter (DPM) concentrations in core DSH 10. An increase in agglutinated taxa from below to within the DPM interval, and a correspondence between tubular agglutinated species and DPM, were revealed. Variations in the ecology of tubular agglutinated taxa imply that this response may have been due to the MOSSFA event as well as a direct response to the DWH spill. Species of the agglutinated genus Trochammina are major contributors to assemblages prior to and after DPM deposition. Elemental analysis of DPM and published geochemistry on the DSH 10 cores suggest that DPM deposition was the result of the MOSSFA event, and certain agglutinated species are potentially oil spill event indicators.

Lost large pieces of fishing gear (FG) have well-documented impacts on marine ecosystems, yet the environmental risks of their degradation products remain poorly understood. Assessing these risks requires quantifying the microplastics, nanoplastics, and associated chemicals generated by different FG types. However, regional-scale data on FG used, lost, and beached are scarce. Using the Southeastern Bay of Biscay as a case study, we applied models to estimate the quantities of used and lost plastic FG. Additionally, eight beaches were sampled in four seasons during 2023. Fishing-related items were identified by FG origin using a novel identification key specifically developed for this purpose. Once fishing related items were identified by FG origins, their polymers were determined by ATR-FTIR. In total, we estimated that 211 tons of plastic FG were used and 6 tons were lost in 2023. Gillnets (2.7 tons), and longlines (2.5 tons), were the most frequently lost FG. Altogether, 7.6 % of items collected in the beaches were identified as coming from the fishing sector. Of these, 89.8 % of the items were mending pieces, 2.6 % were lines, and 2.5 % were longlines. In total, we estimated that 3 tons of FG were beached in the coastline during the studied period. Regarding polymer composition, polyethylene and polypropylene accounted for 95.1 % of the FG and polyamide for 3.3 %. This study presents a useful methodology and provides new data for the identification and quantification of used, lost, and beached plastic FG, contributing to future assessments of the environmental risk associated with their degradation products.

This study provides the first directly comparable estimates of seawater contamination with microplastics (MPs, 0.3-5 mm) and mesoplastics (MePs, 5-25 mm) during the five sampling expeditions in November and December 2024 in the south-eastern part of the Baltic Sea. Bulk seawater sampling was carried out in two nearby locations simultaneously during different stages of storm activity on sandy and pebbly sea shores. The polymeric composition of the microparticles was identified using μ-Raman and FTIR spectroscopy. The maximum abundance of MPs in seawater near pebbly and sandy shores was 1360 and 1300 items/m, respectively. The maximum content of MPs was 12,160 items/m in water samples with sand suspension near pebbly shores. The average abundance of MePs was 35.6 times higher during the storm compared to the post-storm period at both stations combined. Two key trends were observed during the post-storm period: (i) a decrease in average fiber length, and (ii) an increase in the ratio of MPs to MePs. This confirms that storms in swash zone lead to the fragmentation of large plastic particles into microplastics.

Microbial communities normally consist of generalists and specialists. Ship ballast tank is a special ecological system containing abundant bacteria, yet the mechanisms that shape the diversity patterns of generalists and specialists therein remain poorly understood. Here, the taxonomic and phylogenetic diversity, environmental adaptation and assembly processes of generalists and specialists were systematically examined in ballast sediments. Our results showed generalists were more widely distributed but their richness and variations were significantly lower than those of specialists. Firmicutes and Proteobacteria dominated the bacterial composition of generalists and specialists, respectively. Moreover, complex co-occurrence network was contributed by specialists and it played a more important role in the biodiversity maintenance of ballast sediments. Generalists had broader adaptation to the majority of environmental properties than the specialists, particularly for heavy metals. Stochastic processes, especially "undominated" and dispersal limitation dominated the community assembly of generalists and specialists, respectively. Furthermore, the influence of deterministic processes was higher on the assembly of specialists as compared to generalists. Besides, SO could mediate the balance between stochastic and deterministic processes in the assembly of both generalists and specialists. Importantly, stochastic dispersal or sulfate-mediated deterministic selection occurring in these communities can pose invasion risks through ship transport. Overall, our study provides fresh views into the bacterial community and its ecological processes in ballast sediments, and offers targeted insights into its management.

Coastal substratum topography shapes microhabitat conditions both directly, by modulating abiotic environmental factors, and indirectly, by influencing the establishment of topography-associated biota. Consequently, structural differences between natural rocky shores and modern engineered coastal infrastructure are expected to alter microhabitat formation in urban seascapes, by reshaping interactions between topography, abiotic conditions, and biogenic habitat structure. Here, we tracked the development of microclimate conditions (temperature, light, humidity) across 12 months on three eco-engineered panel designs installed on an intertidal seawall. Abiotic factors were assessed at both the panel scale, and at the scale of specific topographic features (outer surfaces, plateaus, overhangs, crevices). Effects of biological colonisation (i.e., canopy cover) were disentangled from direct topographic effects by assessing bare, temporarily installed reference panels at each timepoint. Structurally complex panels exhibited lower mean temperatures, and a greater range of light and humidity conditions than flat panels. Inner topographic features, such as crevices and overhangs, reduced temperatures and light intensities, and increased humidity compared to outer surfaces. Macroalgal canopy formation further reduced most temperature and light parameters, while elevating humidity. These effects occurred irrespective of topography; however, complex panels exhibited cumulative topographic-biogenic effects that created unique microenvironmental conditions not found on flat, colonized panels. Our findings provide quantitative, mechanistic insights into how engineered habitat complexity drives fine-scale microclimate patterns, with practical applications for designing multifunctional, ecologically sustainable coastal infrastructure. Restoring (micro-)habitat conditions on anthropogenically modified shorelines through biomimicry and nature-based solutions is key to enhancing habitat suitability and climate change resilience in urbanized environments.

This study evaluates the ecological risks of oil contamination to endangered seabirds in Algoa Bay, South Africa, linked to ship-to-ship (STS) bunkering activities and other anthropogenic maritime activities. Between 2016 and 2024, 378 oiled seabirds-primarily African penguins and Cape gannets-were admitted to rehabilitation centres, with over half linked to STS-related spills. An established modelling system was used to model the trajectory of oil from the MV Chrysanthi S spill in 2019 (400 L of Heavy Fuel Oil), using the simulated environmental conditions at the time of the spill. The model predicted that core foraging areas would have remained exposed to oil for about a week after the spill and that birds would have been found and rescued days after their contamination. Probabilistic modelling of 200 spill scenarios revealed high likelihoods of shoreline oiling and persistent surface contamination, especially during austral winter, when oil is more likely to reach Bird Island's seabird foraging areas. Spills from the offshore extent of anchorage area 2 are more likely to result in impacts on the seabird foraging areas. The model indicates that a high degree of conservatism is required when selecting ecological thresholds for impacts on African penguins, given the relatively high observed impacts despite low modelled surface thicknesses from a 400 L spill. These findings underscore the urgent need for stricter regulation of offshore bunkering in ecologically sensitive areas and improved preparedness for wildlife rescue and rehabilitation, especially in an area of such high biodiversity as Algoa Bay.

We conducted the largest microplastic (MP) survey ever conducted in the Global South, covering ≈7500 km of the Brazilian coastline and collecting 4134 surface water samples from 1024 beaches across 213 municipalities in 17 states (April 2023-April 2024). Samples were grouped into five coastal macroregions-Amazonian Equatorial, Northeastern, Eastern, Southeastern, and Southern-to align responses and predictors. MPs were quantified by epifluorescence microscopy after Nile Red staining and Calcofluor White/Evans Blue counterstaining, under rigorous quality control procedures. Concentrations showed pronounced spatial heterogeneity, with the Eastern Coastline reaching 16.87 MPs/L, followed by the Northeastern (6.95), Southeastern (5.25), Southern (3.36), and Amazonian Equatorial (1.29 MPs/L). Regional contrasts reflected hydrodynamic and anthropogenic influences: the Eastern sector, characterized by high salinity, elevated pH, and proximity to sewage outlets and highways, exhibited maximum accumulation; the Amazonian Equatorial region, with low salinity, high chlorophyll a, and enhanced surface velocity, showed dissipative conditions and vertical export; and the Southern coast displayed low loads associated with wide shelves and greater distance from point sources. Morphometric analysis revealed a gradient from larger, degraded particles in high-abundance regions to smaller, intact particles in low-abundance regions. Network analysis indicated sparse connectivity in the Eastern Coastline and denser, multi-factorial interactions in the Northeastern and Southeastern regions. These findings establish the first macroregional quantitative baseline of MP pollution in Brazilian marine surface waters, providing a standardized reference for future large-scale monitoring and interregional comparisons.

Skirted oil containment booms are widely used in marine oil spill mitigation, yet their performance under varying hydrodynamic conditions remains a critical challenge. This study presents a combined experimental and numerical investigation to evaluate the oil retention performance of skirted booms across a range of flow velocities, skirt lengths, and inclination angles. Laboratory-scale physical experiments were conducted to observe the dynamic oil-boom interaction, and a validated multiphase numerical model was employed to explore a broader parameter space. The results reveal that oil capture efficiency is highly sensitive to both flow intensity and skirt geometry. At low velocities (u ≤ 0.2 m/s), booms exhibited high retention performance regardless of skirt length. However, with increasing flow velocity, particularly beyond a critical threshold (u ≈ 0.382 m/s), the influence of skirt length became nonlinear, with short skirts failing to maintain effective containment. A critical skirt length was identified, above which oil capture efficiency recovered sharply. Additionally, a performance map in Fr-L/H space illustrated that increasing the skirt inclination angle compressed high-efficiency zones, further reducing containment effectiveness under energetic flow conditions. These findings offer practical guidance for the design and deployment of skirted booms by quantifying key performance thresholds and flow-structure interactions. The integrated approach combining experimental observation and parametric simulation enhances the understanding of failure mechanisms and supports the development of more robust oil spill containment systems.

Microplastics (MPs) are increasingly found alongside pollutants in marine environments, yet their effects on the behavior of these pollutants, such as phthalate esters (PAEs), remain largely unexplored. This study investigated the bioaccumulation and toxicity of dibutyl phthalate (DBP, a prevalent marine PAE) in Mytilisepta virgata (a common mussel in East Asia) in the absence and presence of MPs (polyethylene and polystyrene, in both pristine and naturally aged forms). Results from uptake kinetics revealed that DBP accumulation in mussels varied with the type of co-exposed MPs, likely influenced by their DBP adsorption capacity and density-mediated distribution pattern. Observations from depuration kinetics suggested that the accumulated DBP tended to persist in mussels after exposure to either DBP alone or a combination of DBP and MPs. Lipid peroxidation (LPO) analysis indicated that while MPs did not exacerbate DBP-induced lipid peroxidation with significant differences in LPO levels noted between MP types and aging forms, they could compromise the resilience of mussels to lipid peroxidation. Acute toxicity tests demonstrated that mussels maintained a survival rate of over 90 % at bioavailable levels of DBP, regardless of the presence of MPs. These findings imply that while mussels can thrive, they may risk substantial DBP accumulation and irreversible oxidative damage in marine environments where DBP and MPs coexist, potentially causing negative impacts on mussel population and higher trophic levels. This study provides insights into how MPs influence the fate of coexisting pollutants in marine environments, enhancing our understanding of the ecological risks posed by MPs.

The Western Scheldt is a polluted temperate estuary in the Netherlands and a hotspot for per- and polyfluoroalkyl substances (PFAS), leading to environmental concerns. To assess PFAS contamination, several biota types were sampled in 2023. Reference data was available from 2006 to 2008 and reference material was collected from the Wadden Sea. A spatial gradient in stable isotopes and PFAS concentrations was observed in the estuary. PFAS concentrations were positively correlated with trophic level. For most biota, concentrations were significantly lower than 2006-2008, but significantly higher than the Wadden Sea. Whole-body burdens for marine mammals were extrapolated from liver concentrations to allow further comparison between trophic levels. Biota Magnification Factors for perfluorooctane sulfonic acid (PFOS) ranged between 0.1 and 34, and the Trophic Magnification Factor was 5.7. PFOS concentrations exceeded the European threshold level in flounder and, partly, other fish. Results point at risk of sublethal effects in estuarine biota at several trophic levels.

We measured the concentrations of dissolved oxygen, nutrients, particulate (POC) and dissolved organic carbon (DOC), and their δC values in Lake Sihwa, Korea, during spring (May 2024) and summer (August 2023) to determine the fates of terrestrial and marine POC and DOC. NO mainly originated from freshwater, whereas NH and PO were additionally supplied from bottom sediments in the innermost bay. Although POC and DOC originated primarily from biological production and freshwater, respectively, their δC values provided further insights into their sources and transformation processes, which could not be inferred from bulk concentrations alone. Based on a two end-member mixing model using δC, the spatiotemporal behaviors of terrestrial and marine POC and DOC were identified. Marine POC increased in spring due to enhanced biological production, but decreased markedly in the subsurface layer during summer due to active microbial degradation, contributing to oxygen consumption and the regeneration of nutrients, such as NH and PO. In contrast, terrestrial POC remained in the subsurface layer during summer due to sediment resuspension. Marine DOC was influenced by both biological production and microbial transformation of POC, whereas terrestrial DOC remained largely unaltered, potentially being exported to the open ocean. Thus, our results suggest that in-situ produced marine organic matter (OM) and its subsequent degradation contribute more substantially to the regulation of water quality than the direct input of refractory terrestrial OM, while terrestrial OM is more important for the transport to the open ocean.

To manage the environmental impacts from ballast water and other discharges from ships sailing in waters of the United States, the U.S. Environmental Protection Agency (EPA) put in place the Vessel General Permit (VGP) in 2008. For ships that will install and use a ballast water treatment system (BWTS) to comply with the VGP's requirements for ballast water management, annual reports must be submitted that include the results of sampling and analysis of two types of parameters: bacteria and biocides. From all BWTS, the concentrations of three bacteria must be reported. If a BWTS uses biocides as part of the treatment process, the concentration of relevant biocides and derivatives must also be measured and reported. To date, the United States is the only country to require routine sampling and analysis from ships discharging ballast water into federal waters. We analyzed data submitted to the EPA for a decade (from 2014 to 2023), representing nearly 18,000 reports. First, data were "cleaned", e.g., to remove duplicate reports. Surprisingly, nearly one quarter (23 %) of the reports did not include the required bacteria data. Evaluating the data showed that non-compliance with the parameters' limits was relatively low, <3 % for either of the bacteria (Escherichia coli and enterococci; total heterotrophic bacteria results are only reported, as no limit is stipulated for them). Non-compliance for biocides was <10 %. Evaluating non-compliance of both bacteria and biocides showed more consistency: <2 % of reports were non-compliant for both parameters. Encouragingly, compliance has improved over time, with the best (lowest) non-compliance rates in recent years (2020-2023).

Nutrient enrichment in coastal ecosystems not only degrades water quality but also imposes substantial economic burdens on regional fisheries, tourism, and coastal infrastructure. This study investigates the riverine nutrient inputs and seasonal eutrophication dynamics in the Bohai Rim coastal zone, one of China's most industrially active and economically vital regions. Field observations and secondary datasets from 2022 to 2023 were analyzed for dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), chlorophyll-a, and dissolved oxygen across river mouths and adjacent coastal waters during wet (July) and dry (January) seasons. Results reveal that DIN concentrations consistently exceeded China's Class III seawater standard, with nitrogen loads dominated by agricultural runoff and industrial effluents. Seasonal eutrophication patterns were strongly linked to economic activity: peak nitrogen fluxes in the dry season coincided with higher energy consumption and fertilizer demand. Dissolved oxygen levels frequently dropped below 4 mg L near the Haihe and Liaohe river estuaries, indicating localized hypoxia risk. Econometric estimation suggests that a 10 % reduction in DIN load could yield annual welfare benefits of approximately 1.8 billion CNY, mainly through restored fishery productivity and reduced water treatment costs. Findings emphasize that nutrient management is not merely an ecological issue but an economic imperative-particularly under China's "Beautiful Bay" and "Dual Carbon" policy frameworks. Strengthened river basin governance, nitrogen-use efficiency improvements, and green agricultural transitions are recommended to align coastal water quality protection with sustainable economic development.

Microplastic (MP) pollution and ocean acidification (OA) are co-occurring stressors in coastal ecosystems, yet their combined effects on bivalves remain unclear. We investigated how OA influences MP ingestion, excretion, and physiological performance in the Manila clam Ruditapes philippinarum. Clams were exposed to two pH levels (8.1 and 7.6) for 10 days and three MP concentrations (0, 10, and 1000 items/L) during the final three days. MP accumulation in gills/labial palps and digestive tracts, MP content in excreted material, and filtration and respiration rates were measured. Acidified conditions impaired particle selection, leading to greater MP accumulation in the digestive tract, whereas MP excretion was unaffected. Filtration and respiration were maintained at higher levels under OA, suggesting suppressed stress responses. These results demonstrate that OA enhances MP retention and modulates physiological stress reactions, highlighting synergistic effects that may influence energy balance and ecosystem functioning under future ocean conditions.

This study investigates the short-distance variability in microplastics (MPs) and tire wear particles (TWPs) concentrations in coastal sediment environments, aiming to refine sampling strategies for accurate environmental assessments. Grid sampling was conducted at two Danish sites, Strandby (∼0.57 km, 16 sampling points with distance ranging from 215 to 1070 m) and Odense (∼0.95 km, 13 sampling points, with distances ranging from 215 to 1577 m), followed by MP and TWP extraction and quantification. The results revealed significant variation in MP and TWP concentrations within and between sites, with Odense showing much higher contamination levels than Strandby likely due to the proximity to pollution sources and differences in depositional environments. No TWPs were detected at Strandby, likely due to its distance to road surfaces, as TWPs are made from the friction between tires and road surfaces. Monte Carlo simulations indicated that with 10 sampling points, the mean of the samples has a 50 % probability of being within 94-119 % of the true mean, defined here as the overall mean obtained from this study. The findings underscore the importance of collecting multiple samples to accurately represent MP pollution in the sediment compartment and provide recommendations for future monitoring efforts and sampling strategies.

Understanding how climate influences phytoplankton dynamics is crucial for anticipating temporal trends and cascading consequences on ecosystem functioning under climate change. This study explores long-term dynamics in contrasted Mediterranean lagoons and investigates the effects of climatic (air temperature, rainfall, wind speed) and nutrient (inorganic nutrient concentrations) drivers on phytoplankton chlorophyll a, abundances, and pigment composition. 17 years of summer monitoring were analyzed using univariate trend tests and multivariate approaches to highlight changes and to disentangle the contributions of abiotic factors to phytoplankton variability. Our results revealed contrasts among lagoons in physicochemical conditions and phytoplankton community, which strongly structured their temporal trends. Climatic drivers significantly influenced phytoplankton, but their importance was context-dependent. In nutrient-enriched systems, phytoplankton dynamics were primarily controlled by inorganic nutrient concentrations, while climatic effects were weak by comparison. Conversely, in nutrient-poor systems, climatic signals became more visible and influential: wind events were associated with higher chlorophyll a, warmer conditions with increases in phycoerythrin-rich picocyanobacteria, and rainfall with higher picoeukaryote abundances, potentially through indirect effects on water column stability and nutrient and light availability. However, under nutrient limitation, abundances remained low and dominated by small cells, suggesting that nutrient control exerts the strongest influence on phytoplankton, which may explain why nutrient control tends to mask diffuse climatic signals. Yet, climate change modulates physicochemical patterns and may progressively shape lagoon functioning. This study emphasizes the need to account for lagoon features and vulnerabilities, and supports adaptive and site-specific management strategies to safeguard coastal lagoons under future changes.

One of the biggest issues harming aquatic organisms in marine environments, including fish, is heavy metal (HML) pollution, which can impact the health of people who consume these species. This study aimed to evaluate nine HML (Nickel (Ni), Vanadium (V), Copper (Cu), Chromium (Cr), Cobalt (Co), Iron (Fe), Selenium (Se), Zinc (Zn), and Manganese (Mn) accumulation in three grouper fish (Epinephelus areolatus, Epinephelus bleekeri, and Epinephelus latifasciatus) with the aim of understanding interspecies differences and estimating the associated environmental and health risks. Results reported that the maximum iron concentration (Fe: 67.44 μg/g wet wt basis) was determined in E. areolatus and the minimum V (0.01 μg/g wet wt basis) in E. latifasciatus, while vanadium in E. bleekeri was below the detection limit. However, the order of elements within species was Fe > Zn > Mn > Se > Cu > Cr > Ni > Co > V for E. areolatus and Fe > Zn > Cu > Cr > Ni > Se > Mn > Co > V for E. bleekeri and E. latifasciatus. From a health risk perspective, the estimated dietary intake (EDI-HML) and weekly intake (EWI-HML) values for all HML were below the safety thresholds, suggesting no immediate non-carcinogenic risk. Similarly, contamination indices suggested low overall contamination. However, the carcinogenic risk (CR-HML) values for Ni and Cr exceeded the acceptable limit, suggesting a potential long-term health concern, particularly among children. Continuous monitoring of HML accumulation in edible marine fish and the implementation of pollution control measures are therefore strongly recommended.

The fate of plastic debris that enters the ocean (whether it floats or sinks) remains largely unknown except for plastics found on coastlines. Plastic debris on beaches provide a basis for estimating the return rates of riverine debris derived from land-based sources. Polymer-coated fertilizers represent a traceable form of land-based plastics. These fertilizers use plastic microcapsule as coating agents and are commonly applied to paddy fields in Japan. This study investigates the occurrence and runoff rates of fertilizer-derived microplastics in coastal environments, focusing on their distribution along beaches near river mouths. Samples were collected from 147 plots across 17 beaches along the Japanese coastline. The identified microplastics were composed of polyethylene (PE) and polyurethane (PU). On the Sea of Japan coast, ten beaches contained an average of 18.1 kg ha (670.7 items m), whereas seven Pacific Ocean coast beaches averaged 6.3 kg ha (231.7 items m). We observed two transport pathways: (1) runoff through rivers and (2) direct drainage from paddy fields to beaches. Beached microcapsules transported via rivers represented <0.2 % of the total applied amount, while beaches directly connected to paddy field drainage retained 27.9 %. River runoff resulted in high losses of microcapsules to the open sea, whereas direct drainage led to substantial beach retention. The high areal density of microcapsules indicates that wave and tidal action promotes their accumulation on beaches. Overall, the main transport pathway involves movement from paddy fields into rivers, subsequent entry into the ocean, deposition on beaches, and eventual offshore transport by rip currents.

Anthropogenic debris poses an increasing threat in the marine environment due to its persistence and adverse effects on marine biota and ecosystem services. Previous anthropogenic debris research has centred on shorelines, surface waters, the water column, coastal seafloor and deep-sea domain, leaving sea-caves largely overlooked. This study introduces a novel quantitative approach tailored for sea cave systems, broadening the scope of marine litter research beyond previously targeted environments. All surveyed sea caves contained debris, with densities ranging from 0.044 to 96.839 items m. Most debris was primarily transported via sea-based pathways, and consisted mainly of fragmented plastics (66 %). Occasionally debris was found embedded within tar layers, producing "plastitar" deposits on cave walls. Analyses revealed that wave exposure and available beach area influenced debris retention, while differences in cave architecture resulted in distinct interior spatial deposition patterns across two cave types, leading to the formation of accumulation hotspots. Findings demonstrate that semi-submerged sea caves serve as important reservoirs for anthropogenic marine debris alongside toxic chemical components and potentially associated harmful microbiomes. Such contamination poses risks to sea cave biota and likely compromises the conservation efforts for the Mediterranean monk seal (Monachus monachus).

Global discourse on marine debris requires collective actions translated at multi levels to advance local action. This paper aims to discuss the globally-led discourses on marine debris and its translation into the policy agendas and collaboration at regional, national and local levels. The key argument of this paper is built upon the perspectives from Transnational Governance, Policy Transfer Theory, Multi-Level Governance theory and Collective Action theory. This paper adopted qualitative systematic literature review (SLR) and policy analysis approach using the ROSES (Reporting Standards for Systematic Evidence Syntheses). The existing literature, legal documents, policy, and media content -that generate the empirically driven knowledge- were reviewed and analyzed to understand how global agendas can be effectively extended to regional cooperation that supports marine debris policies in developing countries. The findings show that Indonesia's legal and policy framework, primarily centered on Presidential Regulation No. 83 of 2018, plays an important role in supporting global and regional actions on marine debris through coordination at the national and local levels. There has been good progress, as seen in a 41.68 % reduction of marine plastic waste from 2018 to 2024. However it still far from the 70 % reduction target by 2025 as several challenges remain, such as poor coordination between government levels, weak law enforcement, and the continuous growth of plastic production and use. Thus, this paper concludes that effective marine debris management in Indonesia requires bridging top-down and bottom-up approaches by integrating global frameworks with local realities, ensuring that policies move beyond conservation to include socio-economic and livelihood dimensions, foster collaboration across governance levels, and empower local communities as active partners in long-term, inclusive, and contextually relevant solutions.