Beyond surface: Unveiling ecological and economic ramifications of microplastic pollution in the oceans.

Every year, the global production of plastic waste reaches a staggering 400 million metric tons (Mt), precipitating adverse consequences for the environment, food safety, and biodiversity as it degrades into microplastics (MPs). The multifaceted nature of MP pollution, coupled with its intricate physiological impacts, underscores the pressing need for comprehensive policies and legislative frameworks. Such measures, alongside advancements in technology, hold promise in averting ecological catastrophe in the oceans. Mandated legislation represents a pivotal step towards restoring oceanic health and securing the well-being of the planet. This work offers an overview of the policy hurdles, legislative initiatives, and prospective strategies for addressing global pollution due to MP. Additionally, this work explores innovative approaches that yield fresh insights into combating plastic pollution across various sectors. Emphasizing the importance of a global plastics treaty, the article underscores its potential to galvanize collaborative efforts in mitigating MP pollution's deleterious effects on marine ecosystems. Successful implementation of such a treaty could revolutionize the plastics economy, steering it towards a circular, less polluting model operating within planetary boundaries. Failure to act decisively risks exacerbating the scourge of MP pollution and its attendant repercussions on both humanity and the environment. Central to this endeavor are the formulation, content, and execution of the treaty itself, which demand careful consideration. While recognizing that a global plastics treaty is not a panacea, it serves as a mechanism for enhancing plastics governance and elevating global ambitions towards achieving zero plastic pollution by 2040. Adopting a life cycle approach to plastic management allows for a nuanced understanding of possible trade-offs between environmental impact and economic growth, guiding the selection of optimal solutions with socio-economic implications in mind. By embracing a comprehensive strategy that integrates legislative measures and technological innovations, we can substantially reduce the influx of marine plastic litter at its sources, safeguarding the oceans for future generations.

Enhancing Human Health and Wellbeing through Sustainably and Equitably Unlocking a Healthy Ocean's Potential.

A healthy ocean is essential for human health, and yet the links between the ocean and human health are often overlooked. By providing new medicines, technologies, energy, foods, recreation, and inspiration, the ocean has the potential to enhance human health and wellbeing. However, climate change, pollution, biodiversity loss, and inequity threaten both ocean and human health. Sustainable realisation of the ocean's health benefits will require overcoming these challenges through equitable partnerships, enforcement of laws and treaties, robust monitoring, and use of metrics that assess both the ocean's natural capital and human wellbeing. Achieving this will require an explicit focus on human rights, equity, sustainability, and social justice. In addition to highlighting the potential unique role of the healthcare sector, we offer science-based recommendations to protect both ocean health and human health, and we highlight the unique potential of the healthcare sector tolead this effort.

Anthropocene 129I Record in the Yellow Sea Sediments and Its Indication for River-Delivered Radioactive Pollution to Marginal Seas.

As the number of coastal nuclear facilities rapidly increases and the wastewater from the Fukushima Nuclear Plant has been discharged into the Pacific Ocean, the nuclear environmental safety of China's marginal seas is gaining increased attention along with the heightened potential risk of nuclear accidents. However, insufficient work limits our understanding of the impact of human nuclear activities on the Yellow Sea (YS) and the assessment of their environmental process. This study first reports the 129I and 127I records of posthuman nuclear activities in the two YS sediments. Source identification of anthropogenic 129I reveals that, in addition to the gaseous 129I release and re-emission of oceanic 129I discharged from the European Nuclear Fuel Reprocessing Plants (NFRPs), the Chinese nuclear weapons testing fallout along with the global fallout is an additional 129I input for the continental shelf of the YS. The 129I/127I atomic ratios in the North YS (NYS) sediment are significantly higher than those in the other adjacent coastal areas, attributed to the significant riverine input of particulate 129I by the Yellow River. Furthermore, we found a remarkable 129I latitudinal disparity in the sediments than those in the seawaters in the various China seas, revealing that sediments in China's marginal seas already received a huge anthropogenic 129I from terrigenous sources via rivers and thus became a significant sink of anthropogenic 129I. This study broadens an insight into the potential impacts of terrigenous anthropogenic pollution on the Chinese coastal marine radioactive ecosystem.

A climate vulnerability assessment of the fish community in the Western Baltic Sea.

Marine fisheries are increasingly impacted by climate change, affecting species distribution and productivity, and necessitating urgent adaptation efforts. Climate vulnerability assessments (CVA), integrating expert knowledge, are vital for identifying species that could thrive or suffer under changing environmental conditions. This study presents a first CVA for the Western Baltic Sea's fish community, a crucial fishing area for Denmark and Germany. Characterized by a unique mix of marine, brackish, and freshwater species, this coastal ecosystem faces significant changes due to the combined effects of overfishing, eutrophication and climate change. Our CVA involved a qualitative expert scoring of 22 fish species, assessing their sensitivity and exposure to climate change. Our study revealed a dichotomy in climate change vulnerability within the fish community of the Western Baltic Sea because traditional fishing targets cod and herring as well as other species with complex life histories are considered to face increased risks, whereas invasive or better adaptable species might thrive under changing conditions. Our findings hence demonstrate the complex interplay between life-history traits and climate change vulnerability in marine fish communities. Eventually, our study provides critical knowledge for the urgent development of tailored adaptation efforts addressing existing but especially future effects of climate change on fish and fisheries in the Western Baltic Sea, to navigate this endangered fisheries systems into a sustainable future.

Deep metagenomic sequencing unveils novel SAR202 lineages and their vertical adaptation in the ocean.

SAR202 bacteria in the Chloroflexota phylum are abundant and widely distributed in the ocean. Their genome coding capacities indicate their potential roles in degrading complex and recalcitrant organic compounds in the ocean. However, our understanding of their genomic diversity, vertical distribution, and depth-related metabolisms is still limited by the number of assembled SAR202 genomes. In this study, we apply deep metagenomic sequencing (180 Gb per sample) to investigate microbial communities collected from six representative depths at the Bermuda Atlantic Time Series (BATS) station. We obtain 173 SAR202 metagenome-assembled genomes (MAGs). Intriguingly, 154 new species and 104 new genera are found based on these 173 SAR202 genomes. We add 12 new subgroups to the current SAR202 lineages. The vertical distribution of 20 SAR202 subgroups shows their niche partitioning in the euphotic, mesopelagic, and bathypelagic oceans, respectively. Deep-ocean SAR202 bacteria contain more genes and exhibit more metabolic potential for degrading complex organic substrates than those from the euphotic zone. With deep metagenomic sequencing, we uncover many new lineages of SAR202 bacteria and their potential functions which greatly deepen our understanding of their diversity, vertical profile, and contribution to the ocean's carbon cycling, especially in the deep ocean.

Temporal dynamics of climate change exposure and opportunities for global marine biodiversity.

Climate change is exposing marine species to unsuitable temperatures while also creating new thermally suitable habitats of varying persistence. However, understanding how these different dynamics will unfold over time remains limited. We use yearly sea surface temperature projections to estimate temporal dynamics of thermal exposure (when temperature exceeds realised species' thermal limits) and opportunity (when temperature at a previously unsuitable site becomes suitable) for 21,696 marine species globally until 2100. Thermal opportunities are projected to arise earlier and accumulate gradually, especially in temperate and polar regions. Thermal exposure increases later and occurs more abruptly, mainly in the tropics. Assemblages tend to show either high exposure or high opportunity, but seldom both. Strong emissions reductions reduce exposure around 100-fold whereas reductions in opportunities are halved. Globally, opportunities are projected to emerge faster than exposure until mid-century when exposure increases more rapidly under a high emissions scenario. Moreover, across emissions and dispersal scenarios, 76%-97% of opportunities are projected to persist until 2100. These results indicate thermal opportunities could be a major source of marine biodiversity change, especially in the near- and mid-term. Our work provides a framework for predicting where and when thermal changes will occur to guide monitoring efforts.

The Central Paratethys Sea-rise and demise of a Miocene European marine biodiversity hotspot.

The Miocene Climate Optimum (MCO, ~ 17-14 Ma) was a time of extraordinary marine biodiversity in the Circum-Mediterranean Region. This boom is best recorded in the deposits of the vanished Central Paratethys Sea, which covered large parts of central to southeastern Europe. This sea harbored an extraordinary tropical to subtropical biotic diversity. Here, we present a georeferenced dataset of 859 gastropod species and discuss geodynamics and climate as the main drivers to explain the changes in diversity. The tectonic reorganization around the Early/Middle Miocene boundary resulted in the formation of an archipelago-like landscape and favorable conditions of the MCO allowed the establishment of coral reefs. Both factors increased habitat heterogeneity, which boosted species richness. The subsequent cooling during the Middle Miocene Climate Transition (~ 14-13 Ma) caused a drastic decline in biodiversity of about 67%. Among the most severely hit groups were corallivorous gastropods, reflecting the loss of coral reefs. Deep-water faunas experienced a loss by 57% of the species due to changing patterns in circulation. The low sea level led to a biogeographic fragmentation reflected in higher turnover rates. The largest turnover occurred with the onset of the Sarmatian when bottom water dysoxia eradicated the deep-water fauna whilst surface waters-dwelling planktotrophic species underwent a crisis.

Future trends of marine fish biomass distributions from the North Sea to the Barents Sea.

Climate warming is one of the facets of anthropogenic global change predicted to increase in the future, its magnitude depending on present-day decisions. The north Atlantic and Arctic Oceans are already undergoing community changes, with warmer-water species expanding northwards, and colder-water species retracting. However, the future extent and implications of these shifts remain unclear. Here, we fitted a joint species distribution model to occurrence data of 107, and biomass data of 61 marine fish species from 16,345 fishery independent trawls sampled between 2004 and 2022 in the northeast Atlantic Ocean, including the Barents Sea. We project overall increases in richness and declines in relative dominance in the community, and generalised increases in species' ranges and biomass across three different future scenarios in 2050 and 2100. The projected decline of capelin and the practical extirpation of polar cod from the system, the two most abundant species in the Barents Sea, drove an overall reduction in fish biomass at Arctic latitudes that is not replaced by expanding species. Furthermore, our projections suggest that Arctic demersal fish will be at high risk of extinction by the end of the century if no climate refugia is available at eastern latitudes.

The best of two worlds: reprojecting 2D image annotations onto 3D models.

Imagery has become one of the main data sources for investigating seascape spatial patterns. This is particularly true in deep-sea environments, which are only accessible with underwater vehicles. On the one hand, using collaborative web-based tools and machine learning algorithms, biological and geological features can now be massively annotated on 2D images with the support of experts. On the other hand, geomorphometrics such as slope or rugosity derived from 3D models built with structure from motion (sfm) methodology can then be used to answer spatial distribution questions. However, precise georeferencing of 2D annotations on 3D models has proven challenging for deep-sea images, due to a large mismatch between navigation obtained from underwater vehicles and the reprojected navigation computed in the process of building 3D models. In addition, although 3D models can be directly annotated, the process becomes challenging due to the low resolution of textures and the large size of the models. In this article, we propose a streamlined, open-access processing pipeline to reproject 2D image annotations onto 3D models using ray tracing. Using four underwater image datasets, we assessed the accuracy of annotation reprojection on 3D models and achieved successful georeferencing to centimetric accuracy. The combination of photogrammetric 3D models and accurate 2D annotations would allow the construction of a 3D representation of the landscape and could provide new insights into understanding species microdistribution and biotic interactions.

Innovative and practical tools for monitoring and assessing biodiversity status and impacts of multiple human pressures in marine systems.

Human activities at sea can produce pressures and cumulative effects on ecosystem components that need to be monitored and assessed in a cost-effective manner. Five Horizon European projects have joined forces to collaboratively increase our knowledge and skills to monitor and assess the ocean in an innovative way, assisting managers and policy-makers in taking decisions to maintain sustainable activities at sea. Here, we present and discuss the status of some methods revised during a summer school, aiming at better management of coasts and seas. We include novel methods to monitor the coastal and ocean waters (e.g. environmental DNA, drones, imaging and artificial intelligence, climate modelling and spatial planning) and innovative tools to assess the status (e.g. cumulative impacts assessment, multiple pressures, Nested Environmental status Assessment Tool (NEAT), ecosystem services assessment or a new unifying approach). As a concluding remark, some of the most important challenges ahead are assessing the pros and cons of novel methods, comparing them with benchmark technologies and integrating these into long-standing time series for data continuity. This requires transition periods and careful planning, which can be covered through an intense collaboration of current and future European projects on marine biodiversity and ecosystem health.

Impacts of ocean warming on fish size reductions on the world's hottest coral reefs.

The impact of ocean warming on fish and fisheries is vigorously debated. Leading theories project limited adaptive capacity of tropical fishes and 14-39% size reductions by 2050 due to mass-scaling limitations of oxygen supply in larger individuals. Using the world's hottest coral reefs in the Persian/Arabian Gulf as a natural laboratory for ocean warming - where species have survived >35.0 °C summer temperatures for over 6000 years and are 14-40% smaller at maximum size compared to cooler locations - we identified two adaptive pathways that enhance survival at elevated temperatures across 10 metabolic and swimming performance metrics. Comparing Lutjanus ehrenbergii and Scolopsis ghanam from reefs both inside and outside the Persian/Arabian Gulf across temperatures of 27.0 °C, 31.5 °C and 35.5 °C, we reveal that these species show a lower-than-expected rise in basal metabolic demands and a right-shifted thermal window, which aids in maintaining oxygen supply and aerobic performance to 35.5 °C. Importantly, our findings challenge traditional oxygen-limitation theories, suggesting a mismatch in energy acquisition and demand as the primary driver of size reductions. Our data support a modified resource-acquisition theory to explain how ocean warming leads to species-specific size reductions and why smaller individuals are evolutionarily favored under elevated temperatures.

Ocean warming and acidification adjust inter- and intra-specific variability in the functional trait expression of polar invertebrates.

Climate change is known to affect the distribution and composition of species, but concomitant alterations to functionally important aspects of behaviour and species-environment relations are poorly constrained. Here, we examine the ecosystem ramifications of changes in sediment-dwelling invertebrate bioturbation behaviour-a key process mediating nutrient cycling-associated with near-future environmental conditions (+ 1.5 °C, 550 ppm [pCO2]) for species from polar regions experiencing rapid rates of climate change. We find that responses to warming and acidification vary between species and lead to a reduction in intra-specific variability in behavioural trait expression that adjusts the magnitude and direction of nutrient concentrations. Our analyses also indicate that species behaviour is not predetermined, but can be dependent on local variations in environmental history that set population capacities for phenotypic plasticity. We provide evidence that certain, but subtle, aspects of inter- and intra-specific variation in behavioural trait expression, rather than the presence or proportional representation of species per se, is an important and under-appreciated determinant of benthic biogeochemical responses to climate change. Such changes in species behaviour may act as an early warning for impending ecological transitions associated with progressive climate forcing.

Assessing Chlorophyll-a Variations in Caspian Sea during the COVID-19 Pandemic.

The COVID-19 pandemic's disruptions to human activities prompted serious environmental changes. Here, we assessed the variations in coastal water quality along the Caspian Sea, with a focus on the Iranian coastline, during the lockdown. Utilizing Chlorophyll-a data from MODIS-AQUA satellite from 2015 to 2023 and Singular Spectrum Analysis for temporal trends, we found a 22% Chlorophyll-a concentration decrease along the coast, from 3.2 to 2.5 mg/m³. Additionally, using a deep learning algorithm known as Long Short-Term Memory Networks, we found that, in the absence of lockdown, the Chlorophyll-a concentration would have been 20% higher during the 2020-2023 period. Furthermore, our spatial analysis revealed that 98% of areas experienced about 18% Chlorophyll-a decline. The identified improvement in coastal water quality presents significant opportunities for policymakers to enact regulations and make local administrative decisions aimed at curbing coastal water pollution, particularly in areas experiencing considerable anthropogenic stress.

Unveiling a new oceanic anoxic event at the Norian/Rhaetian boundary (Late Triassic).

The latest Triassic was characterised by protracted biotic extinctions concluding in the End-Triassic Extinction (~ 200 Ma) and a global carbon cycle perturbation. The onset of declining diversity is closely related to reducing conditions that spread globally from upper Sevatian (uppermost Norian) to across the Norian-Rhaetian boundary, likely triggered by unusually high volcanic activity. We correlate significant organic carbon cycle perturbations to an increase of CO2 in the ocean-atmosphere system, likely outgassed by the Angayucham igneous province, the onset of which is indicated by the initiation of a rapid decline in 87Sr/86Sr and 188Os/187Os seawater values. A possible causal mechanism involves elevated CO2 levels causing global warming and accelerating chemical weathering, which increased nutrient discharge to the oceans and greatly increased biological productivity. Higher export production and oxidation of organic matter led to a global O2 decrease in marine water across the Norian/Rhaetian boundary (NRB). Biotic consequences of dysoxia/anoxia include worldwide extinctions in some fossil groups, such as bivalves, ammonoids, conodonts, radiolarians.

Survey on Perkinsus species in two economic mussels (Mytilus coruscus and M. galloprovincialis) along the coast of the East China Sea and the Yellow Sea.

Perkinsus, a parasitic pathogen of marine bivalves, is widely distributed among various mollusks in numerous countries. However, the prevalence and diversity of Perkinsus species in the two economically important mussels, Mytilus coruscus and M. galloprovincialis, in China remain unknown. The presence of the Perkinsus species was identified in the two mussels sampled along the coast of the East China Sea and the Yellow Sea, using both the alternative Ray's fluid thioglycolate medium (ARFTM) and conventional polymerase chain reaction (PCR). The ARFTM test indicated the presence of Perkinsus-like hypnospores in the two mussels. The diameter of the hypnospores in M. coruscus was significantly smaller than that in M. galloprovincialis. The prevalence of Perkinsus in M. galloprovincialis and M. coruscus ranged from 0 to 37.5% and 0 to 25%, respectively. The mean intensity of Perkinsus in M. galloprovincialis and M. coruscus ranged from 0 to 5.14 and 0 to 4.92, respectively. The PCR assay showed that the prevalence of Perkinsus spp. in M. galloprovincialis and M. coruscus was 0 to 25.0% and 0 to 12.5%, respectively. The homology analysis of the newly obtained internal transcribed spacer (ITS) sequences of Perkinsus revealed the highest identity of 100% with P. beihaiensis. The phylogenetic analysis indicated that the Perkinsus isolates from the two mussels were clustered with P. beihaiensis. The results of the molecular biology indicated that only P. beihaiensis was detected in the two mussels. The highest prevalence of P. beihaiensis was observed in Liaoning province (Dalian, 20.83%), followed by Shandong province, Zhejiang province and Fujian province. Consequently, it is recommended that surveillance should be conducted in Dalian, where the prevalence and mean intensity of P. beihaiensis in M. galloprovincialis are the highest.

Global expansion of marine protected areas and the redistribution of fishing effort.

The expansion of marine protected areas (MPAs) is a core focus of global conservation efforts, with the "30x30" initiative to protect 30% of the ocean by 2030 serving as a prominent example of this trend. We consider a series of proposed MPA network expansions of various sizes, and we forecast the impact this increase in protection would have on global patterns of fishing effort. We do so by building a predictive machine learning model trained on a global dataset of satellite-based fishing vessel monitoring data, current MPA locations, and spatiotemporal environmental, geographic, political, and economic features. We then use this model to predict future fishing effort under various MPA expansion scenarios compared to a business-as-usual counterfactual scenario that includes no new MPAs. The difference between these scenarios represents the predicted change in fishing effort associated with MPA expansion. We find that regardless of the MPA network objectives or size, fishing effort would decrease inside the MPAs, though by much less than 100%. Moreover, we find that the reduction in fishing effort inside MPAs does not simply redistribute outside-rather, fishing effort outside MPAs would also decline. The overall magnitude of the predicted decrease in global fishing effort principally depends on where networks are placed in relation to existing fishing effort. MPA expansion will lead to a global redistribution of fishing effort that should be accounted for in network design, implementation, and impact evaluation.

Onset of coupled atmosphere-ocean oxygenation 2.3 billion years ago.

The initial rise of molecular oxygen (O2) shortly after the Archaean-Proterozoic transition 2.5 billion years ago was more complex than the single step-change once envisioned. Sulfur mass-independent fractionation records suggest that the rise of atmospheric O2 was oscillatory, with multiple returns to an anoxic state until perhaps 2.2 billion years ago1-3. Yet few constraints exist for contemporaneous marine oxygenation dynamics, precluding a holistic understanding of planetary oxygenation. Here we report thallium (Tl) isotope ratio and redox-sensitive element data for marine shales from the Transvaal Supergroup, South Africa. Synchronous with sulfur isotope evidence of atmospheric oxygenation in the same shales3, we found lower authigenic 205Tl/203Tl ratios indicative of widespread manganese oxide burial on an oxygenated seafloor and higher redox-sensitive element abundances consistent with expanded oxygenated waters. Both signatures disappear when the sulfur isotope data indicate a brief return to an anoxic atmospheric state. Our data connect recently identified atmospheric O2 dynamics on early Earth with the marine realm, marking an important turning point in Earth's redox history away from heterogeneous and highly localized 'oasis'-style oxygenation.

Forecasting of compound ocean-fluvial floods using machine learning.

Flood modelling and forecasting can enhance our understanding of flood mechanisms and facilitate effective management of flood risk. Conventional flood hazard and risk assessments usually consider one driver at a time, whether it is ocean, fluvial or pluvial, without considering the compound nature of flood events. In this paper, we developed a novel approach for modelling and forecasting compound coastal-fluvial floods using a two-step framework. In step one, a hydrodynamic model is used to simulate floodwater propagation; while in step two, machine learning (ML) models are used to generate flood forecasts. The architecture of hydrodynamic-ML forecasting system incorporates a hydrodynamic model covering a specific domain, with individual ML models trained for each pixel. In total 7 ML models including: Support Vector Regression (SVR), Support Vector Machine (SVM), Radial Basis Function (RBF), Linear Regression (LR), Gaussian Process Regression (GPR), Decision Tree (DT), and Artificial Neural Network (ANN) were applied in this study. Forecasting compound floods is achieved using two sets of inputs: timeseries of river discharges in the upstream fluvial section and downstream ocean water levels in the coastal areas. The accuracy of the flood forecasting system is demonstrated for Cork City, Ireland; and modelling performance was evaluated using several statistical tools. Results show that the proposed models can provide reliable estimates of flood inundation and associated water depths. Overall, the RBF model exhibits the best performance. Despite the complexity of compound multi-driver floods, this study shows that the coupled hydrodynamic-ML approach can forecast coastal-fluvial flood with limited hydraulic and hydrological input data. This system overcomes the limitations of traditional hydrodynamic model-based systems where trade-offs between the always competing numerical model accuracy and computational time prohibit the model to be used for short-term flood forecasting. Once trained, the ML component of the coupled system can perform flood forecasting in near real-time, potentially integrating into a flood early warning system. Accurate flood forecasting has a wide range of positive societal impacts, including improved flood preparedness, increased confidence, better resource allocation, reduced flood damage, and potentially even flood prevention.

Dissolved trace elements in the Ganges-Brahmaputra-Meghna River Basin: A new approach for estimating trace element flux inputs from rivers into the world's oceans.

Understanding the changes in the chemical compositions of dissolved trace elements from source to sink is important for determining their spatiotemporal variations and the contributions from each sub-catchment in the Ganges, Brahmaputra, and Meghna Rivers. To estimate weathering and matter transfer in these Rivers and the Ganges-Brahmaputra-Meghna (G-B-M) Estuary, we measured 15 dissolved trace element concentrations from surface and bottom water samples and exchangeable trace metals from suspended particulate matter (SPM). From December 2019 to January 2020, post-monsoon samples were collected from the upstream of the three rivers and the G-B-M Estuary. Dissolved trace elements in the Ganges and Meghna Rivers exhibited remarkable spatial variations, whereas those in the Brahmaputra River and the G-B-M Estuary were uniform. The dissolved trace elements, basic information (river length and drainage area), and physicochemical parameters (pH, dissolved oxygen, and conductivity) of the three rivers were inconsistent. The sample sites near urban areas and industrial centers had high concentrations of dissolved trace elements. In the G-B-M Estuary, iron and lead concentrations decreased along the salinity gradient, whereas selenium levels gradually increased, which may have been released by the SPM owing to its highly exchangeable trace metals. Compared with historical concentrations, trace elements that entered the G-B Estuary from the Ganges and Brahmaputra Rivers exhibited either decreased or increased metal fluxes due to additional terrigenous sources, suggesting that the inputs of trace element flux from the Ganges and Brahmaputra Rivers into the oceans may need to be re-evaluated. Furthermore, Fe and Pb concentrations and river fluxes in the Ganges and Changjiang have decreased in recent years. Hence, the fluxes of certain trace elements that enter the oceans from large rivers may require re-evaluation.