Search Results (215)

Snails at hydrothermal vents rely on symbiotic bacteria for nutrition; however, the specifics of these associations in adapting to such extreme environments remain underexplored. This study investigated the community structure and metabolic potential of bacteria associated with two Indian Ocean vent snails, Chrysomallon squamiferum and Gigantopelta aegis. Using microscopic, phylogenetic, and metagenomic analyses, this study examines bacterial communities inhabiting the foot and gland tissues of these snails. G. aegis exhibited exceptionally low bacterial diversity (Shannon index 0.14–0.18), primarily Gammaproteobacteria (99.9%), including chemosynthetic sulfur-oxidizing Chromatiales using Calvin–Benson–Bassham cycle and methane-oxidizing Methylococcales in the glands. C. squamiferum hosted significantly more diverse symbionts (Shannon indices 1.32–4.60). Its black variety scales were dominated by Campylobacterota (67.01–80.98%), such as Sulfurovum, which perform sulfur/hydrogen oxidation via the reductive tricarboxylic acid cycle, with both Campylobacterota and Gammaproteobacteria prevalent in the glands. The white-scaled variety of C. squamiferum had less Campylobacterota but a higher diversity of heterotrophic bacteria, including Delta-/Alpha-Proteobacteria, Bacteroidetes, and Firmicutes (classified as Desulfobacterota, Pseudomomonadota, Bacteroidota, and Bacillota in GTDB taxonomy). In C. squamiferum, Gammaproteobacteria, including Chromatiales, Thiotrichales, and a novel order “Endothiobacterales,” were chemosynthetic, capable of oxidizing sulfur, hydrogen, or iron, and utilizing the Calvin–Benson–Bassham cycle for carbon fixation. Heterotrophic Delta- and Alpha-Proteobacteria, Bacteroidetes, and Firmicutes potentially utilize organic matter from protein, starch, collagen, amino acids, thereby contributing to the holobiont community and host nutrition accessibility. The results indicate that host species and intra-species variation, rather than the immediate habitat, might shape the symbiotic microbial communities, crucial for the snails’ adaptation to vent ecosystems. Full article

Deep-sea mining presents a critical sustainability paradox; it offers access to essential minerals for the technologies of the green transition (e.g., batteries, wind turbines, electric vehicles) yet threatens fragile marine ecosystems. As the terrestrial sources of these materials face mounting geopolitical, environmental, and ethical constraints, undersea deposits are increasingly being viewed as alternatives. However, the extraction technologies remain unproven at large scales, posing risks related to biodiversity loss, sediment disruption, and altered oceanic carbon cycles. This paper explores how deep-sea mining might be reconciled with sustainable development, arguing that its viability hinges on addressing five interdependent challenges—technological readiness, environmental protection, economic feasibility, robust governance, and social acceptability. Progress requires parallel advancements across all domains. This paper reviews the current knowledge of deep-sea resources and extraction methods, analyzes the ecological and sociopolitical risks, and proposes systemic solutions, including the implementation of stringent regulatory frameworks, technological innovation, responsible terrestrial sourcing, and circular economy strategies. A precautionary and integrated approach is emphasized to ensure that the securing of critical minerals does not compromise marine ecosystem health or long-term sustainability objectives. Full article

This study focused on the carbonate system dynamics and air–sea CO₂ fluxes in the open-ocean waters of the Madeira–Tore Seamount Complex during August 2024. Surface water properties revealed pronounced latitudinal gradients in sea surface temperature (21.9–23.1 °C), salinity (36.2–36.7), and dissolved oxygen (228–251 µmol Kg⁻¹), influenced by mesoscale eddies and topographically driven upwelling. Despite oligotrophic conditions, distinct phytoplankton assemblages were observed, with coccolithophores dominating southern seamounts and open-ocean stations, and green algae and diatoms indicating episodic nutrient input. Surface total alkalinity (TA: 2236–2467 µmol Kg⁻¹), dissolved inorganic carbon (DIC: 2006–2183 µmol Kg⁻¹), and pCO₂ (467–515 µatm) showed spatial variability aligned with water mass characteristics and biological activity. All stations exhibited positive air–sea CO₂ fluxes (2.8–11.5 mmol m⁻² d⁻¹), indicating the region is a CO₂ source during summer. Calcite and aragonite saturation states were highest in stratified, warmer waters. Principal Component Analysis highlighted the role of physical mixing, carbonate chemistry, and biological uptake in structuring regional variability. Our findings emphasize and contribute to the complex interplay of physical and biogeochemical drivers in modulating carbon cycling and ecosystem structure across Atlantic seamounts. Full article

The Upper Carboniferous strata in the eastern Qaidam Basin, comprising several hundred meters of thick, mixed clastic–carbonate successions that have been little reported or explained, provide an excellent geological record of paleoenvironmental and paleo-sea level changes during the Late Carboniferous icehouse period. This tropical carbonate–clastic system offers critical constraints for correlating equatorial sea level responses with high-latitude glacial cycles during the Late Paleozoic Ice Age. Based on detailed outcrop observations and interpretations, five facies assemblages, including fluvial channel, tide-dominated estuary, wave-dominated shoreface, tide-influenced delta, and carbonate-dominated marine, have been identified and organized into cyclical stacking patterns. Correspondingly, four third-order sequences were recognized, each composed of lowstand, transgressive, and highstand system tracts (LST, TST, and HST). LST is generally dominated by fluvial channels as a result of river juvenation when the sea level falls. The TST is characterized by tide-dominated estuaries, followed by retrogradational, carbonated-dominated marine deposits formed during a period of sea level rise. The HST is dominated by aggradational marine deposits, wave-dominated shoreface environments, or tide-influenced deltas, caused by subsequent sea level falls and increased debris supply. The sequence stratigraphic evolution and geochemical records, based on carbon and oxygen isotopes and trace elements, suggest that during the Late Carboniferous period, the eastern Qaidam Basin experienced at least four significant sea level fluctuation events, and an overall long-term sea level rise. These were primarily driven by the Gondwana glacio-eustasy and regionally ascribed to the Paleo-Tethys Ocean expansion induced by the late Hercynian movement. Assessing the history of glacio-eustasy-driven sea level changes in the eastern Qaidam Basin is useful for predicting the distribution and evolution of mixed cyclic succession in and around the Tibetan Plateau. Full article

With the increasingly stringent regulation of ship carbon emissions by the International Maritime Organization (IMO), improving ship energy efficiency has become a key research direction in the current shipping industry. This paper proposes and evaluates a comprehensive energy-saving solution that integrates a wind-assisted propulsion system (WAPS) and an organic Rankine cycle (ORC) waste heat power generation system. By establishing an energy efficiency simulation model of a typical ocean-going cargo ship, the appropriate optimal system configuration parameters and working fluids are determined based on minimizing the total fuel consumption, and the impact of these two energy-saving technologies on fuel consumption is systematically analyzed. The simulation results show that the simultaneous use of these two energy-saving technologies can achieve the highest energy efficiency, with the maximum fuel savings of approximately 21%. This study provides a theoretical basis and engineering reference for the design of ship energy-saving systems. Full article

The Earth’s degassing is an important factor in evaluating global carbon budget estimates and understanding the carbon cycle. As a result, numerous studies have focused on this topic. However, current estimates predominantly focus on subaerial CO₂ emissions and CO₂ deep submarine emissions, particularly along mid-ocean ridges (MORs), whereas very few and only spatially limited estimates of shallow submarine CO₂ emissions have been reported, despite being widespread features of the seafloor. This study reports the results of measuring the dissolved CO₂ concentrations in shallow submarine environments along the coast of Vulcano Island (Aeolian Islands, Italy). For the areas exhibiting the highest concentrations, we calculated the amount of diffuse degassing by computing the sea–air CO₂ flux. The results revealed extremely high dissolved CO₂ concentrations, reaching up to 24 vol.% in areas with visible hydrothermal activity, including one location far from the island’s main crater. Notably, elevated CO₂ levels were also detected in areas with minimal or no apparent hydrothermal discharge, indicating the occurrence of diffuse degassing processes in these areas. In addition, the calculated diffuse degassing flux was comparable in magnitude to the CO₂ flux directly emitted into the atmosphere from the island’s main bubbling pools. Full article

The Yangzhuang Formation of the Mesoproterozoic Jixian System exhibits a well-developed carbonate sedimentary sequence. However, the carbonate cycles within the Yangzhuang Formation and their co-evolution with paleoclimate and paleoceanographic environment changes remain insufficiently studied. This study conducts a systematic investigation of the rhythmic layers of the Yangzhuang Formation within the Yanshan Basin, North China, through major and trace element analysis, rare earth element analysis, inorganic carbon isotope analysis, granulometric analysis, and time series analysis. The results show that the low content of terrigenous clastics (11.2%~32.6%), slow sedimentation rate (2.2–2.5 cm/ka), Mg/Ca molar ratio close to 1 (1.05–1.53), and small fluctuation of δ¹³C_carb (−0.37‰~−0.05‰) in Member 3 of the Yangzhuang Formation constitutes the processes of co-evolution, along with a mid-phase fluctuation. It indicates the stable evolution of the sedimentary environment and slow ocean expansion speed. However, there is a fluctuating characteristic affected by the breakup of the Colombian supercontinent. The chemical and granulometric analysis of the red and gray layers shows that the terrigenous materials are mainly derived from the eolian sediments, with differences in the wind carrying materials. The time series analysis of the dense samples displays the coupling between the rhythm of the red and gray layers, the inorganic carbon isotope cycle, and the 15 ka precessional cycle in the Mesoproterozoic. We conclude that the rhythm of layers is mainly affected by the monsoon change driven by low-latitude solar radiation at that time, and the age of the Yangzhuang Formation is limited to 1550~1520 ± 2 Ma. The study of the Mesoproterozoic sequence using geochemical data from carbonate deposits reveals the underlying mechanism of global co-evolution during this period, providing a basis for understanding the evolution of the Mesoproterozoic Earth system. Full article

Dinoflagellates significantly contribute to the carbon fixation and microbial loop in the ocean with high ecological diversity. While the microbial communities associated with the HABs of dinoflagellates have attracted intensive attention in recent years, little attention has been paid to the microbiomes associated with resting cysts, an important stage in the life cycle and bloom initiation dynamics of dinoflagellates. Using Scrippsiella acuminata as a representative of cyst producers and cyst-relevant research in dinoflagellates, we surveyed the bacteria and fungi microbiomes long associated with different life cycle stages of the dinoflagellate culture through 16S and ITS rRNA amplicon sequencing, and predicted their possible functions using the PICRUSt2 algorithm. The results found high species diversity of the associated bacteria–fungi microbiomes, and species featured with diverse and flexible metabolic capabilities that have stably co-occurred with the laboratory culture of S. acuminata. The host-attached and the free-living groups of bacteria–fungi microbiomes, as operationally defined in the context, showed significant differences in terms of their nutritional preferences. The bacteria–fungi species diversity and community structure associated with cysts are also distinguished significantly from that with vegetative cells, with the latter attracting more bacteria–fungi species specializing in phosphate solubilization. These results suggest that the relative species abundance and thus the community structure of the host-associated microbiome shift with the transition of life cycle stages and environmental conditions. Our findings show the association tightness between bacteria–fungi microbiomes and dinoflagellate hosts and the different life stages of hosts shaping the bacteria–fungi communities, which result in dynamic and specific interactions between bacteria–fungi microbiomes and their hosts. Full article

The ocean is one of the world’s largest anthropogenic carbon dioxide (CO₂) sinks, but closing the carbon budget is logistically difficult and expensive, and uncertainties in carbon fluxes and reservoirs remain. One specific challenge is that measuring the CO₂ flux at the air–sea interface usually requires costly sensors or analyzers (USD > 30,000), which can limit observational capacity. Our group has developed and validated a low-cost ΔpCO₂ system, able to measure both pCO₂^water and pCO₂^air, for USD ~1400 to combat this limitation. The device is equipped with Internet of Things (IoT) capabilities and built around a USD ~100 pCO₂ K30 sensor at its core. Our Sensor for the Exchange of Atmospheric CO₂ with Water (SEACOW) may be placed in an observational network with traditional pCO₂ sensors or ∆pCO₂ sensors to extend the spatial coverage and resolution of monitoring systems. After calibration, the SEACOW reports atmospheric pCO₂ measurements that are within 2–3% of the measurements made with a calibrated LI-COR LI-850. We also demonstrate the SEACOW’s ability to capture diel pCO₂ cycling in seagrass, provide recommendations for SEACOW field deployments, and provide additional technical specifications for the SEACOW and for the K30 itself (e.g., air- and water-side 99.3% response time; 5.7 and 29.6 min, respectively). Full article

Carbonate sedimentation was spread widely on the southern margin of the Neo-Tethys Ocean in the mid-Cretaceous. New information from four exploration wells sheds light on the peculiarities of the Sarvak Formation (late Albian–Cenomanian) at the narrow transition between the Dezful Embayment and Coastal Fars in the southern Zagros. The solution of this task was necessary to understand whether the fragmentation of the Zagros Basin into domains affected the carbonate platform development. The methods included the analyses of carbonate microfacies, paleoecological patterns of foraminifera, and depositional environments. The results of this study show the existence of ten carbonate microfacies. Prevailing wackestones and packstones with a muddy matrix and absent carbonate buildups imply the development of a large carbonate ramp. Paleoecological interpretations based chiefly on foraminifers prove this model. For instance, the presence of oligosteginids signifies shallower parts of the platform, and the cooccurrence of planktonic foraminifera and oligosteginids suggests a deeper environment. The stratigraphical distribution of the established microfacies in the wells indicates three cycles in the evolution of this platform. The third of these cycles marked an abrupt deepening episode because it includes microfacies suggesting the relatively deeper environments. Three maximum flooding surfaces established in the study area are common to the Arabian plate. The discussion of the results suggests that the influence of the Kazerun fault on the carbonate ramp in the Cenomanian is uncertain. Neither eustatic nor tectonic factors of the carbonate platform development can be excluded. Conclusively, it appears that the studied Cenomanian carbonate ramp was integral at the transition between the Dezful Embayment and Coastal Fars. Full article

Ocean color remote sensing technology has proven to be an indispensable tool for monitoring ocean conditions, as it has consistently provided critical data on global ocean optical properties, color, and biogeochemical parameters over several decades. With the rapid advancement of artificial intelligence, the integration of machine learning (ML) models into ocean color remote sensing has become a significant focus within the scientific community. This article provides a comprehensive review of the current status and challenges associated with ML models in ocean color remote sensing, assessing their applications in atmospheric correction, color inversion, carbon cycle analysis, and data reconstruction. This review highlights the advancements made in applying ML techniques, such as neural networks and deep learning, to improve data accuracy, enhance resolution, and enable more precise predictions of oceanic phenomena. Despite challenges such as model generalization and computational complexity, ML has significant potential for enhancing our understanding of marine ecosystems, facilitating real-time monitoring, and supporting global climate models. Full article

Among different kinds of renewable energy sources, ocean wave energy offers a promising source of low-carbon electricity. However, despite this potential, ocean wave energy systems can have notable environmental impacts, which remain underexplored. Environmental life cycle assessment (LCA) is a method that can be used to evaluate the environmental impact of these systems. But few LCAs have been conducted for wave energy converters (WECs), and no prior studies specifically address onshore oscillating water column (OWC) devices, leaving a clear gap in this field. This research provides a cradle-to-gate LCA for an OWC device, using the 500 kW LIMPET OWC plant, located on the Isle of Islay in Scotland, as a case study. The assessment investigated the environmental impacts of the plant across 19 impact categories. OpenLCA 2.0 software was used for the analysis, with background data sourced from the Ecoinvent database version 3.8. The ReCiPe 2016 Midpoint (H) and Cumulative Energy Demand (CED) methods were used for the impact assessment. The results revealed a Global Warming Potential (GWP) of 56 kg CO₂ eq/kWh and a carbon payback period of 0.14 years. The energy payback period is significantly higher at 196 years, largely due to the plant’s inefficient energy capture and recurring operational failures reported. These findings highlight that although ocean wave energy is a renewable energy source, WEC’s efficiency and reliability are key factors for sustainable electricity generation. Furthermore, the findings conclude the need for selecting eco-friendly construction materials in OWC construction, namely chamber construction, and the advancement of energy-harnessing mechanisms, such as in Power Take-off (PTO) systems, to improve energy efficiency and reliability. Moreover, the importance of material recycling at the end-of-life stage, which was not accounted for in this cradle-to-gate analysis yet, is underscored for offsetting a portion of the associated environmental impacts. This research contributes novel insights into sustainable construction practices for OWC devices, offering valuable guidance for future wave energy converter designs. Full article

Particulate organic carbon (POC) plays a crucial role in oceanic climate change. However, existing research is limited by several factors, including the scarcity of long-term data, extensive datasets, and a comprehensive understanding of POC dynamics. This study utilizes monthly average POC remote sensing data from the MODIS/AQUA satellite to analyze the spatiotemporal variations of POC in the East China Sea from 2003 to 2022. Employing correlation analysis, spatial autocorrelation models, and the Geodetector model, we explore responses to key influencing factors such as climatic elements. The results indicate that POC concentrations are higher in the western nearshore areas and lower in the eastern offshore regions of the East China Sea (ECS). Additionally, concentrations are observed to be lower in southern regions compared to northern ones. From 2003 to 2022, POC concentrations exhibited a fluctuating downward trend with an average annual concentration of 121.05 ± 4.57 mg/m³. Seasonally, monthly average POC concentrations ranged from 105.48 mg/m³ to 158.36 mg/m³; notably higher concentrations were recorded during spring while summer showed comparatively lower levels. Specifically, POC concentrations peaked in April before rapidly declining from May to June—reaching a minimum—and then gradually increasing again from June through December. Correlation analysis revealed significant influences on POC levels by particulate inorganic carbon (PIC), sea surface temperature (SST), chlorophyll (Chl), and photosynthetically active radiation (PAR). The Geodetector model further elucidated that these factors vary in their impact: Chl was identified as having the strongest influence (q = 0.84), followed by PIC (q = 0.75) and SST (q = 0.64) as primary influencing factors; PAR was recognized as a secondary factor with q = 0.30. This study provides new insights into marine carbon cycling dynamics within the context of climate change. Full article

The Gulf of Mexico (GoM) is a complex oceanic basin with a maximum depth of 4000 m. It is a complex hydrodynamic system formed by different water masses with distinctive physical and biological characteristics that shape its rich biodiversity. In this study, as a contribution to better understanding the microbial communities inhabiting the meso- and bathypelagic zones of the Mexican Exclusive Economic Zone (EEZ) of the GoM, an extensive set of seawater samples was collected at three depths (350–3700 m) during three oceanographic cruises. The V4-16S rRNA gene analysis identified Pseudomonadota (27.1 ± 9.8%) and Nitrosopumilales (26.4 ± 2.3%) as the dominant bacterial and archaeal members, respectively. The depth, salinity, and apparent oxygen utilization were key environmental drivers, which explained 35% of the community variability. The mesopelagic zone presented a more homogeneous structure characterized by a nitrifier community, while the bathypelagic was more heterogeneous, with hydrocarbon-degrading bacteria and methanogens serving as the key players. This study is the first to report the archaeal community in the deeper waters of the Mexican EEZ of the GoM, playing crucial roles in the nitrogen and carbon cycles, highlighting the region’s ecological complexity and the need for further research to understand the broader biogeochemical implications of these processes. Full article

The Pliensbachian–Toarcian boundary and early Toarcian events indicate significant environmental and oceanographic instabilities attributed to the emplacement of the Karoo–Ferrar large igneous province and subsequent greenhouse gas emissions. These geologic processes influenced carbon cycle perturbations and global warming, consistent with phases of a sea level rise. This study presents a high-resolution dataset of total organic carbon (TOC) and bulk rock geochemistry and mineralogy from a complete upper Pliensbachian–Toarcian interval of the Quse Formation at the Qixiangcuo section in the Southern Qiangtang Basin. The Qixiangcuo section consists of carbonate and siliciclastic organic carbon-poor sediments deposited in a shallow-shelf setting in the eastern Tethys Ocean. Chemostratigraphic data, including Ti, Zr, U, Ca, Mn, and Sr and their ratios normalized to Al, record characteristic changes linked to sea level evolution and resulting depositional sequences. Trends in these geochemical data allow for the subdivision of the Quse Formation into nine complete third-order transgressive–regressive sequences, referred to as Pliensbachian sequences PSQ1 and PSQ2, Toarcian sequences TSQ1 to TSQ7, and one incomplete sequence. Elemental proxies indicative of terrigenous detrital input and sediment grain size along with a mineralogical composition of quartz, plagioclase, and clay minerals exhibit similar trends. Increased values of these proxies suggest a sea level fall and the deposition of regressive systems tract (RST) sediments, with peak values indicating a maximum regressive surface (MRS), and vice versa for transgressive systems tract (TST) sediments and the maximum flooding surface (MFS). On the contrary, rising trends in calcite content and carbonate-bound elements indicate phases of a relative sea level transgression, reaching maximum values at the MFS, while declining trends mark a sea level regression. The Sr/Ca ratio exhibited inverse patterns to the carbonate proxies, in part, with rising values indicating a sea level fall and vice versa. Full article