The oil spill resulting from the grounding of the MV Wakashio on a reef off the coast of Mauritius in July 2020 was the world's first major spillage of Very Low Sulfur Fuel Oil (VLSFO) since the implementation of a Global Sulfur Cap from January 2020. In this study, we examine sediments collected in March 2023 from two Mauritius mangrove systems. Analyses by both gas chromatography-mass spectrometry and comprehensive two-dimensional gas chromatography confirmed, by comparison of molecular biomarkers, the presence of Wakashio VLSFO in one of the mangrove systems. The spilled oil had undergone extensive weathering resulting in substantial losses of toxic mono- and polycyclic aromatic compounds. Applying WebGNOME-ADIOS oil spill models to compare the fate of Wakashio VLSFO with traditional fuels suggests that more of the VLSFO would evaporate, naturally disperse, and undergo sedimentation compared to traditional fuels that were more likely to remain floating.

Jellyfish blooms can significantly impact marine food webs, biochemical processes and human health, disrupting various economic sectors, including fisheries, aquaculture and tourism. Thus, understanding the regional drivers and patterns of jellyfish occurrence is key for developing effective management strategies. The Portuguese man o' war (Physalia physalis) is a hazardous, cosmopolitan siphonophore of particular concern, requiring a deeper ecological understanding to effectively guide mitigation efforts. Our study reveals that the occurrence of P. physalis in both the North Atlantic (Azores, Portugal) and the Southeast Pacific (Australian East Coast) is driven by region-specific wind patterns and increased primary productivity (>30 % model contribution), with warming conditions emerging as an additional occurrence driver on the Australian East Coast (∼20 % model contribution). These insights resulted from machine learning models (Boosted Regression Trees) trained with high-resolution environmental data against field data describing the temporal variability of P. physalis occurrence (North Atlantic: 2008-2021; Southeast Pacific: 2016-2020). The models achieved excellent predictive performance (AUC North Atlantic: 1.00; AUC Southeast Pacific: 0.92) and allowed hindcasting occurrences over 30 years, uncovering contrasting trends between the two regions, with decadal fluctuations in the Azores and a significant increase in occurrence over time on the Australian East Coast. Overall, we provide a better understanding of the drivers and patterns of P. physalis occurrence, which can support the development of coastal management strategies. Importantly, the anticipated changes in productivity and temperature conditions in both regions may result in increased blooms in the years to come, further exerting impacts on the ecosystems, human health, and the economy.

This research evaluated the emission characteristics of old ships during typical operations, under varying cruising speeds, and during lock transit, using a shaft power meter and PEMS. The research revealed that upstream and downstream low-load voyages accounted for 67.9 % and 65.4 % of the total voyage, respectively. The average emission factors of CO, NO and CO were highest under lock transit with 17.13±0.51 g/kWh, 16.2±0.62 g/kWh and 1075.37±5.72 g/kWh, respectively, while SO was highest under manoeuvring with 0.46 ± 0.001 g/kWh. Emissions are closely correlated with engine speed, with the largest emissions at cruising, and emissions at departure and docking significantly concentrated in the 10-15 % and 5-10 % loads. This research emphasizes the importance of considering low-load operating conditions in engine test cycles and provides data support for maritime decarbonization and emission reduction strategies. Future research should continue to explore the emission characteristics of old ships.

Global warming poses a significant threat to coral reefs. It has been assumed that mesophotic coral ecosystems (MCEs, 30 to 150 m depths) may serve as refugia from ocean warming. This study examined the acclimation capacity and thermal tolerance of two shallow coral species, Porites cylindrica and Turbinaria reniformis, transplanted to mesophotic depths (40 m) for 12 months. Fragments from 5 and 40 m were exposed to control (28 °C), moderate (30 °C), and high (32 °C) temperatures over 14 days. MCE-acclimated fragments showed higher thermal thresholds and survival rates, delayed onset of bleaching, and less decline in photosynthesis efficiency (Fv/Fm) compared to shallow fragments. Both species maintained high thermal tolerance despite prolonged exposure to cooler temperatures of mesophotic depth. These findings suggest that low light intensity in MCEs can act as a modulator of bleaching, supporting the potential of these ecosystems as refugia for shallow corals in a rapidly changing world.

Early to intermediate ontogenetic stages of trees are important in forest regeneration. However, these critical life stages are often overlooked due to survey intensity and impracticality and/or disinterest in characterizing early life stage cohorts. This problem is particularly pervasive in mangrove forests where visibility of smaller stature trees may be limited by tidal flooding and younger cohorts are particularly vulnerable to changing hydrologic and biogeochemical conditions driven by climate change. Lacking data on early life stages in mangrove forests makes it difficult to predict ecosystem degradation and inform habitat resilience and restoration in one of the earth's most valuable blue carbon ecosystems. We identify challenges to collecting empirical data on early to intermediate age classes in mangroves and provide solutions to characterizing these cohorts. We emphasize the importance of gathering these data for improved understanding of forest regeneration dynamics and provide multi-scalar solutions to quantify vegetation structure of mangrove forest.

The Baltic Sea highly susceptible to the proliferation of Phytoplankton blooms. Present work examines the long-term trend and spatio-temporal variability of satellite derived chlorophyll concentration (Chl a) in the Baltic Sea during the period 2004-2021. Furthermore, the influence of water quality and meteorological parameters on Baltic Sea primary productivity has been analyzed using robust Generalized Additive Models (GAM) and Granger Causality statistical test. Statistically significant increasing trend in chlorophyll a concentration is observed in the Baltic Sea at the 95 % confidence interval. GAM model reveals that the most significant controlling factor is sea surface temperature (p < 0.0001), followed by nitrate and phosphate. Both GAM and Granger Causality tests confirm that water quality parameters are the major drivers in limiting the growth of Phytoplankton blooms in the Baltic Sea. Summer bloom shows in-phase relationship with Sea surface temperature and out of phase relationship with the phosphate nutrient.

Heavy metal pollution in aquatic ecosystems can lead to harmful accumulation in organisms like stingrays, posing potential health risks to humans. To assess this risk, 45 stingrays were sampled from Johor Waters (Pontian, Muar, and Batu Pahat) and analyzed for heavy metal content using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The average concentrations of Cu, Zn, As, Cd, Pb, and Hg in the fillets were 0.982±0.637, 31.3±5.93, 93.57±24.5, 0.039±0.047, 0.158±0.036, and 0.592±0.424 μg/g dw, respectively. Arsenic (As) was found at the highest concentration. The study indicates that fish size does not directly influence heavy metal accumulation and that metal levels vary by location. Calculated consumption limits for different metals are crucial for human safety. This data is valuable for evaluating contamination risks and guiding future research to protect marine ecosystems in Johor Waters.

Owing to the heterogenous distribution of contaminated sediments in urban estuaries, contaminant residues, such as polychlorinated biphenyls (PCBs), in fish tissue can vary widely. To investigate the relationship between PCBs in fish tissue and heterogeneity of PCBs in sediment, we developed a geospatial Biota-Sediment Accumulation Factor (BSAF) model for an urban estuary. The model predicts whole fish total PCB residues at a scale of 0.1 km by incorporating sediment chemistry, fish home range, and habitat type. The model predicted concentrations from across the estuary ranging from 0 to 161,456 ng/g lipid. An estuary-wide (50+ km) and a project-scale (1+ km) field validation of the model demonstrated it produced values that were slightly skewed to low concentrations; performance improved with increased sediment data spatial coverage. We conclude this approach has potential for determining PCBs "hot spot," estimating remediation project footprints, and evaluating potential remediation improvements to the quality of a fishery.

Sharks, are highly vulnerable to fishing pressures, a key factor in their global population decline. Chemical pollution, however, especially metal and metalloid contamination, poses significant additional risks. Of around 520 shark species, about 170 are threatened, including the Sphyrna genus (hammerheads). This review examines contamination in these sharks and its ecological and human health implications. A scientometric review indicates limited research, mainly on juveniles and only mercury contamination, with scarce data on other metals, life stages, and consumption thresholds. The findings also indicate a certain amount of Colonial Science concerning ecotoxicological Sphyrna spp. assessments. The expected link between ecotoxicological risks and Sphyrna spp. threat status remains inconclusive due to insufficient data. Notably, larger hammerhead species do not always exhibit higher contamination levels, suggesting that local environmental factors may influence contamination more than biological characteristics. More research is required to understand how environmental pressures impact shark vulnerability and inform conservation strategies.

With the development of the cruise industry, the associated pollution and social impact issues are becoming more severe. The objective of this study is, therefore, to identify the significant impact factors in the cruise development process and to analyze their effects on the natural environment, economy and society. To this end, the study first identified the dimensions and criteria through interviews with experts and a literature review, grouping the dimensions of impact cost into 'natural environment', 'economic' and 'social' using the best-worst method (BWM) resulting in four impact factors included under each dimension, totalling 12 criteria. Methodologically, these criteria were sorted by weight using BWM, resulting in the six most influential factors, which were, in order, 'wastewater, oil pollution and toxic substances', 'exhaust gas and noise', 'low consumption willingness and failure to meet expectations', 'causing urban congestion and traffic jams', 'changing the residents' original lifestyle' and 'vectors of infectious disease transmission'. Following this, the causal diagrams between the various criteria were drawn with the causal relationships between the factors analyzed using the decision-making trial and evaluation laboratory (DEMATEL) method. The results of the study showed that 'causing urban congestion and traffic jams' is the key core factor directly affecting the other five. These findings can assist the cruise industry and the local government in formulating effective preventive and improvement measures to minimise the negative environmental and social impacts of cruise development and to ensure the sustainable development of the industry. This study also has important implications for future management and policy formulation in the cruise industry.

Microplastics are everywhere, including marine sediment. In this study, we evaluated the degradation of polyester, rayon, and cotton sewing threads over nine months when buried in marine sediment in Waitematā Harbour, Auckland, New Zealand. Polyester tensile strength was tested pre- and post-burial to track changes over time. Fourier-transform infrared spectroscopy (FTIR) analysis enabled the examination of the change to the chemical structural integrity of the polyester molecules over time. After one month, rayon and cotton degraded and were invisible to the eye, while visible signs of polyester degradation were apparent after 6 months of burial. This was confirmed by both tensile strength testing and FTIR chemical analysis. While microplastic pollution remains a serious problem, these findings show that at least one type of common plastic does degrade when buried in marine sediments. This likely has implications for seafloor ecosystem functionality and provides hope for plastic circular economy infrastructure.

With global warming, extreme weather frequently occurs, yet the consequences remain unexplored. A total of 156 heat waves and their characteristics were detected on the basis of a temperature dataset from 1954 to 2022 in Jiaozhou Bay (JZB). The increment is 0.62 times decade for the number of heat waves, 6.65 days decade for the sum of participating heat wave days and 0.66 days for the duration of each heat wave. The intensity of heat waves showed regular fluctuations with progressively shorter periods. Based on the dataset of 12 stations in JZB from 2003 to 2022, the zooplankton abundance was significantly greater during heat waves, which was strongly attributed to the greater abundance of copepods and gelatinous zooplankton during heat waves. However, the responses of plankton to heat waves were seasonally heterogeneous. Our study provides new insight into and a scientific basis for understanding the effects of heat waves on offshore plankton ecosystems.

This study extensively investigated the abundance of microplastics in Thiruvottiyur coastal area of Chennai, India, before and after Cyclone Michaung. The results demonstrated a significant correlation between microplastic distribution and aftermath rainfall. The concentration of microplastics in sediments increased from 150 ± 48 particles kg to 186 ± 21 particles kg after the cyclone. In seawater, the concentration rose from 1.28 particles L to 3.65 particles L, respectively. Heavy metals such as Al, Mg, Zn, Cr, Pb, Cu, Cd, Co, and As were detected on the surface of microplastics, demonstrating their vectorization potential for co-contaminants. After exposure, these microplastics induced oxidative stress in Artemia franciscana with increased superoxide dismutase (SOD), catalase, and reactive oxygen species (ROS). Fluctuations in weather conditions lead to heterogeneous changes in microplastic distribution, revealing the seasonal dynamics of microplastics. This study will provide background information to devise strategies for mitigating microplastic pollution in the marine environment.

Blue carbon cycling in mangrove ecosystems is proving to be more complex than previously thought. The objective of this study was the application of structural equation modelling (SEM) to capture such complex and varying data types and provide a holistic understanding of mangrove blue carbon cycling using data from the Indian Sundarban as a test case. We found that SEM was effective at integrating multiple data types and characterizing the processes and variables that regulate the nature and magnitude of CO fluxes within a mangrove ecosystem, including atmosphere-hydrosphere, atmosphere-pedosphere, and net ecosystem exchange. Overall, this study finds that atmospheric, water, and soil temperatures were the main and common drivers of CO effluxes towards the atmosphere from the entire ecosystem, waterbodies, and soils of mangrove ecosystems, respectively. We conclude that SEM is useful for combining data from different sources, gaining an overarching view of the complex biogeochemical cycling of the blue carbon ecosystems.

Sea turtles can host a wide range of parasitic taxa, some of which may lead to severe diseases, weakening and endangering their health. Assessing free-ranging sea turtles' responses to these potential pathogens using biomarkers can provide valuable insights into the cellular and molecular impacts of parasites. This information can serve as a crucial tool for conservation efforts. During rehabilitation, hematological, genotoxic and innate immune parameters were evaluated in 70 free-ranging sea turtles rescued along the Southern Adriatic coast (Eastern Mediterranean Sea) from 2021 to 2023, 24 of which were found to have parasitic infections. Hapalotrema mistroides, Sulcascaris sulcata and Neospirorchis sp. were identified by coprological and molecular techniques. Some significant differences for biomarkers were associated with these parasites. These findings highlight the importance of considering the infection status of free-ranging sea turtles when evaluating biomarker results, as major pathogens like parasites can influence certain parameters.

The high number of offshore platforms at the end of their productive phase offers the opportunity of their re-use and the development of effective management solutions, such as the possibility of utilizing them as ecological observatories for monitoring marine ecosystems and their biological resources. Here, through a multiparametric observatory deployed at an unproductive offshore platform, located in the Central Adriatic Sea (Mediterranean Sea), we collected data for 13 months on benthopelagic fish assemblage and habitat conditions. A total of 155.5 h of high-frequency (30 min) video-monitoring, recorded higher fish abundances during spring-summer periods during daytime, while fish diversity was highest in autumn. Some environmental variables contributed significantly to explain the overall community variance. Our results suggest that offshore platforms can be re-converted into ecological observatories, to collect relevant amounts of information that can be difficulty obtained with alternative approaches, contributing to our understanding of changes occurring in open water ecosystems.

Advanced satellite technology and algorithms are making substantial progress in meeting the need for improved environmental monitoring of coastal waterways. Integrating high-resolution satellites with in-situ radiometric equipment is essential for effectively monitoring algal blooms and managing coastal resources. Our work has built a model to examine geographical and temporal fluctuations in chlorophyll-a concentration in Bushehr Bay, Persian Gulf, Iran, using radiometric data and high-resolution remote sensing. In this study, we used twenty-four bio-optical features for analysis. After evaluating and selecting the most important features, we used the top five features to estimate chlorophyll-a concentration using machine learning algorithms. Likewise, the model could effectively investigate our climatology of chlorophyll in the study area. Our findings provide a dependable approach to monitor the environmental effect of chlorophyll-a and enhance water quality and regional management of primary production in coastal waters. This proposed proxy may be implemented in comparable places globally.

The drifting speed and trajectory of fish aggregation devices (FADs) influence tuna aggregation behavior. Based on expertise, fishermen modify FAD structures to slow down drifting speed, but few studies quantify material and structure effects on this speed. To address this, 14 different types of FAD models were tested under 5 different current velocities in a flume tank and compared drifting using pairwise Wilcoxon tests. Results indicate that 1) FAD models covered with netting exhibited higher drifting speeds than the others. 2) It is feasible that replacing the netting bundle with the cotton rope of the same diameter for constructing submerged structure effectively slows down the drifting speeds of FADs. 3) Additionally, FAD models with a floating structure aspect ratio close to 1 exhibited slower drifting speeds compared to other designs when the submerged structure is the same.

Suspended sediment and salinity stresses may escalate under climate change in inshore turbid habitats. We test whether fertilization and embryonic development of Acropora tumida and Platygyra carnosa are less prone to both stressors in turbid coral habitats compared to thresholds reported in literature for species found in clear water reefs. Under optimal sperm concentration (10 sperm mL), fertilization of A. tumida declined by 50 % when exposed to combined sediment (92 mg L) and salinity stresses. However, these stressors had no significant impact on P. carnosa. We found ∼20- and ∼ 7-fold increases in abnormal embryos for A. tumida and P. carnosa, respectively, under combined stressors. Furthermore, silicon-rich terrestrial-originated sediment caused 50 % larval mortality for A. tumida at a lower concentration of 53 mg L. We showed that climate change-related salinity and sediment stresses may hinder coral reproduction and challenge coral recovery, questioning the coral survival in nearshore turbid habitats.

The Canadian Arctic is a large and diverse geographic area that encompasses a wide variety of environmental conditions and ecosystems. Over recent decades, marine transportation has increased across the Arctic and, as a result, so has the likelihood of an oil spill. The study of oil spills in the Arctic presents unique challenges compared to temperate marine environments, due to remoteness, cold temperatures and the presence of snow and ice throughout much of the year. This review summarizes and discusses the fate of oil in the Canadian Arctic. A brief introduction to the Canadian Arctic and sources of potential petroleum spills is provided, followed by discussions of the behaviour of oil in ice and freezing temperatures, oil-sediment interactions, and the weathering and natural remediation of oil under Arctic conditions. A summary of perspectives concludes the review, with emphasis on possible areas of future work to address research gaps.