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Zirconium (Zr) stable isotopes recently emerged as potential tracers of magmatic processes and, as a result, their behavior in high-temperature environments have been the focus of extensive characterization. In contrast, few studies have focused on Zr behavior and isotopic fractionation in low temperature or aqueous environments. Here, we describe a new analytical routine for highly precise and accurate analysis of Zr isotopes of water samples, using a combination of double-spike and iron co-precipitation methods. To assess the impact of potential systematic biases a series of experiments were conducted on natural and synthetic water samples. Our results show that the spike-to-sample ratio, matrix composition, and high field-strength element (HFSE) concentration have negligible effects on measured seawater Zr isotopic compositions, and that the Fe co-precipitation method used yields accurate and precise Zr isotope data. We thus apply this method to natural seawater samples collected from a water column profile in the Pacific Ocean off the coast of California, with depths ranging from 5 to 711 m. We find that the natural seawater samples are highly fractionated relative to solid-Earth values and display marked variability in δ 94/90Zr as a function of depth, ranging from ∼ +0.650 ‰ near the surface, to + 1.530 ‰ near the profile bottom, with an analytical uncertainty of ± ∼0.045 ‰ (2 SE, external reproducibility). The δ 94/90Zr value of seawater is much higher than that of Earth's mantle and continental crust, which has a δ 94/90Zr value near zero, indicating the presence of processes in the hydrosphere capable of inducing large mass-dependent fractionation. Furthermore, the seawater δ 94/90Zr value exhibits systematic variations with respect to water depth and salinity, suggesting that Zr isotopic compositions may be sensitive to seawater chemical properties and source highlighting its potential utility as a tracer of biogeochemical processes within the ocean. [ABSTRACT FROM AUTHOR]

The concentrations of dissolved iron (DFe), iron-binding ligands (L Fe), and electroactive humic-like substances (eHS) were revealed in the upper 200 m along the 170°W latitudinal transect of the central Pacific Ocean in summer, which was weakly influenced by terrestrial input. DFe was largely depleted throughout the transect, except in the Bering Sea, and below 100 m in the North Pacific Subarctic Gyre. The concentration of L Fe was lowest within the subtropical gyres and was lower in the Southern Hemisphere, which is consistent with the results from the Atlantic Ocean. The vertical distribution of L Fe was relatively constant in the subtropical regions, whereas in the subarctic regions the subsurface maximum appeared around or over the subsurface chlorophyll maximum at some stations. The higher concentration of L Fe in the subarctic regions coincides with a lower stability constant, which suggests a higher contribution of weaker ligands, including humic and exopolymeric substances. The horizontal and vertical distribution patterns of eHS were largely similar to those of L Fe , supporting their significant contribution to iron-binding capacity in the upper 200 m, particularly in the subarctic regions. However, the eHS concentration was only weakly correlated with that of the fluorescently determined humic-like substances, demonstrating the substantially different chemical properties of the two humic-like substances. The strong positive correlation between the concentrations of eHS and chlorophyll a and Synechococcus strongly suggests their biological origins. However, further research is required to examine whether eHS are directly produced by phytoplankton or released via relevant biological processes, such as grazing, bacterial composition, and viral lysis. • Iron chemical speciation was revealed from the South Pacific to the Bering Sea. • Humics play a substantial role in iron chemistry in the surface open water. • Microbial processes seem more important in ligand dynamics than photodecomposition. [ABSTRACT FROM AUTHOR]

A new Dracoderidae genus, Dracophyes gen. nov., and a new species Dracophyes cepedai sp. nov. from the Peru Basin are described. The new genus is characterized by the presence of acicular spines showing conspicuous intracuticular structures on segments 1–9 (either anchor for the dorsal or groove-like for the lateral series), alternating laterally displaced dorsal spines, becoming more lateral towards the posterior segments, males with two pairs of minute, poorly sclerotized penile spines, and its conspicuous obovate trunk shape. The new genus accommodates three species: Dracophyes toyoshioae comb. nov., Dracophyes chaac comb. nov. and D. cepedai sp. nov. The latter was collected in abyssal depths in the Peru Basin (East Pacific Ocean) and is recognised by having dorsal acicular spines on segments 1 to 9, alternating laterally displaced from the middorsal line, ventral acicular spines in ventrolateral position on segment 1, lateroventral position on segments 2–4 and 6–9, and in lateral accessory position on segment 5, tubes in lateroventral position on segment 5 and in lateral accessory position on segments 2 and 8, type 2 glandular cell outlets in lateroventral position on segment 10 and extremely long lateral terminal spines. Moreover, with the erection of the new genus, emended diagnoses for the family Dracoderidae and the former single genus within the family, Dracoderes , are proposed. [ABSTRACT FROM AUTHOR]

Beach littering is a source of marine plastic waste accumulation. This is particularly so in overcrowded beaches in the Global South in which cleaning measures are scarce or sporadic and lack of waste management systems can increase plastic release. In the current study we focus on the importance of the behavior shown by beachgoers and how their conduct relates to the amount of plastic that potentially ends up entering littoral ecosystems. Transportation services to beaches, sports, food, and beverage containers are analyzed through a 24-question survey performed to 500 beachgoers in 4 beaches (i.e., Venecia, Punta Negra, Punta Hermosa and San Bartolo) located in the megacity of Lima, Peru, in February 2022. The data obtained were then processed to understand the differences in behavior across different beaches. Moreover, a K-means algorithm was used to identify representative beachgoer profiles. The results showed a dichotomous behavior between two groups of beaches, in which the size group of beachgoers, transportation mode, accommodation, food consumption patterns or the use of reusable containers are some of the main differences between the two groups. No major differences were identified in terms of age distribution across the different beaches, but group sizes were higher in Punta Negra and Villa El Salvador. The K-means algorithm suggests that the surveyed population can be grouped into three main categories, of which two correspond mainly to higher socioeconomic beachgoers in the beaches of Punta Hermosa and San Bartolo. Overall, single use plastic for food and beverages appears as one of the main sources of plastic pollution across beaches and groups, although other sources of plastic emission should not be underestimated. Finally, the three beachgoer profiles identified are useful to implement targeted policies to minimize the environmental impacts of these profiles. [Display omitted] • A 24-question survey was performed to 500 beachgoers in beaches in Lima, Peru. • The survey focused on understanding how beachgoers generate direct or indirect plastic emissions. • Behavior was analyzed across and within the beaches assessed. • A dichotomous behavior between two groups of beaches was identified in most of the variables assessed. • The use of the K-means algorithm allowed identifying three distinct beachgoer profiles. [ABSTRACT FROM AUTHOR]

Strontium isotopic ratios (⁸⁷Sr/⁸⁶Sr) in sedimentary and igneous rocks may provide valuable interpretations that allow constraining the geologic evolution of sedimentary basins. We present a new ⁸⁷Sr/⁸⁶Sr dataset from sedimentary units in the southern Central Andes (33°–34°S)—coupled to available isotopic information of igneous rocks—to examine the paleogeographic evolution of the Andes at the western margin of South America during the Mesozoic. These new data was obtained from shales, limestones and fine-grained sandstones from Mesozoic formations in the Coastal Cordillera and the Principal Cordillera of the main Andes. The new Sr-isotopic data on the Mesozoic sedimentary rocks can be grouped by both rock type and location: a) Continental red sandstones: 0.7038–0.7124; b) Calcareous rocks of the main Andes (Principal Cordillera): 0.7070–0.7081; and c) Calcareous rocks of the Coastal Cordillera: 0.7041–0.7067. The ⁸⁷Sr/⁸⁶Sr signatures in most of the clastic units in both Cordilleras are related to an evolved or enriched magmatic source for clasts and matrix indicating different sources. On the other hand, the Sr-isotopic composition of calcareous rocks differs between the units in the Andean and the Coastal mountain belts: shales and limestones in the Principal Cordillera of the Andes display ⁸⁷Sr/⁸⁶Sr ratios corresponding to the contemporary ocean in the Late Jurassic and Early Cretaceous; whereas the carbonatic units in the Coastal Cordillera do not show a relation with any oceanic signatures. The Sr-isotopic compositions of the Andean carbonatic units in the Principal Cordillera support the interpretation of their marine depositional environment in the paleo Pacific Ocean. In contrast, carbonate rock samples from the formations in the Coastal Cordillera suggest that they formed in brackish-water depositional basins made by topographic highs partially disconnected from the ocean. In the case of clastic rocks, their Sr-isotopic compositions provide insights into the contributions derived from the magmatic arc to the clastic units. Therefore, the Sr-isotopic composition of the sedimentary rocks provides a new dataset which can improve our understanding of the geological evolution of the southern Central Andes. • A new set of 87Sr/86Sr ratios for Mesozoic sedimentary rocks in the Southern Andes. • The 87Sr/86Sr of calcareous rocks varies across the Andean and Coastal cordilleras. • 87Sr/86Sr in calcareous rocks in the Andes correspond to the contemporary ocean. • 87Sr/86Sr in calcareous rocks in the Coastal range indicate continental sources. • The contrasting 87Sr/86Sr accros the margin have paleogeographic implications. [ABSTRACT FROM AUTHOR]

We provide evidence of anthropogenic materials ingestion in seabirds from a remote oceanic area, using regurgitates obtained from black-legged kittiwake (Rissa tridactyla) chicks from Middleton Island (Gulf of Alaska, USA). By means of GPS tracking of breeding adults, we identified foraging grounds where anthropogenic materials were most likely ingested. They were mainly located within the continental shelf of the Gulf of Alaska and near the Alaskan coastline. Anthropogenic cellulose fibers showed a high prevalence (85 % occurrence), whereas synthetic polymers (in the micro- and mesoplastics dimensional range) were less frequent (20 %). Most fibers (60 %) were blue and we confirmed the presence of indigo-dyed cellulosic fibers, characteristic of denim fabrics. In terms of mass, contamination levels were 0.077 μg g−1 wet weight and 0.009 μg g−1 wet weight for anthropogenic microfibers and synthetic polymers, respectively. These results represent the only recent report of contamination by anthropogenic fibers in seabirds from the Gulf of Alaska. [Display omitted] • We screened kittiwake's chick regurgitates from Alaska for anthropogenic fibers. • Cellulosic fibers occurred in 85 % of regurgitates, while synthetic polymers in 20 %. • μ-RAMAN spectroscopy confirmed that some cellulosic microfibers were indigo-dyed. • Regurgitates are an effective tool for monitoring contamination of Arctic food webs. [ABSTRACT FROM AUTHOR]

Charge distribution measurements are required to understand the spatiotemporal distribution of the number concentrations of submicron atmospheric particles that affect radiative forcing and particle deposition in human airways. The number concentrations of non-charged and charged particles within the 0.3–0.5 μm diameter (D) range were measured at Keio University in Yokohama, Japan, from June 2022 to January 2023 by combining a parallel-pate particle separator and optical particle counters to investigate critical parameters controlling the charging state of submicron atmospheric particles. The measurement uncertainties in the average charge number per particle (p ave) and the standard deviation (1 σ), derived from the charge distribution of the submicron particles, were within 15%. The monthly median values of 1 σ increased in summer and decreased in winter and correlated with the water vapor amount and wind speed. The 1 σ values in summer and winter, derived from the seasonally averaged charge distributions of particles, were close to those from the theoretically calculated charge distribution of particles within 0.387–0.5 μm D range and with D = 0.3 μm, respectively, suggesting that the observed particle charge distributions approached the stationary charge distribution for the effective D. In summer, the frequent transport of water molecules and ions from the Pacific Ocean causes efficient collisions between multiple ions and submicron particles with a larger effective D , which may expand the charge distribution of particles. The polarity ratio, the concentration of positively charged particles relative to that of negatively charged particles, was almost unity, indicating the well-balanced charge polarity of the submicron atmospheric particles. The polarity ratio and p ave changed significantly during lightning events, indicating that the atmospheric particle charge balance broke. Our findings show that the charge distribution of submicron atmospheric particles can be partly controlled by meteorological parameters (e.g., absolute humidity) and the microphysical properties of the particles. • We observed charge distribution of submicron particles at Yokohama, Japan. • Charge distribution of submicron particles was expanded in summer. • Particle charge distribution was controlled by the water vapor amount. • Non-charged particle fraction value was consistent with a previous study. • Lightning events changed the particle polarity ratio and charge distribution. [ABSTRACT FROM AUTHOR]

In August 2023, the Tokyo Electric Power Company (TEPCO), with permission of the Japanese government, began to release treated water stored on the site of the Fukushima Dai'ichi nuclear power plant into the Pacific Ocean. Given their unprecedented nature in terms of scale and duration, with over one million tons of water to be released over thirty years, the releases have drawn international scholarly attention from marine policy, law, conservation and social sciences, as well as from policy and science-media sectors more widely. The purpose of this communication is therefore to provide an international audience with an outline of the processes through which the decision to release the treated water was made; and of the institutions and policy frameworks that govern the treated water releases from Fukushima Dai'ichi. [ABSTRACT FROM AUTHOR]

We analyse the wave energy resource available along the Pacific coast of South America from Panama from the latitude of 8°N to the Drake Passage at 55°S. The analysis is based on wave time series over 63 years (1959–2021) from the European Union Copernicus database constructed using the WAM wave model for the entire Pacific forced by wind information from ERA5. The novel features are the analysis of temporal variations in the wave energy flux, quantification of the contribution of swells and wind-seas into the wave energy potential, establishing properties of the most energy-carrying wave conditions, and evaluation of the role of El Niño and La Niña in the wave energy potential. The annual average wave energy flux increases from about 2 kW/m just to the north of the equator on the Colombian Pacific coast to 20–50 kW/m in the central and southern mainland of Chile and up to 80 kW/m near the Drake Passage. The wave energy resource to the north of latitude 32°S is almost entirely provided by swells. To the south of 44°S wind-seas predominate among the most energetic wave conditions and the maxima of energy flux by wind-seas up to 20 times exceed the already high average energy flux. The temporal variation in the wave energy flux follows the same pattern. It is fairly small at lower latitudes and increases rapidly from the forties. The magnitude of seasonal variation in terms of monthly mean wave energy flux is commonly from −47% to +32% from the long-term mean. The calmest time that contains 1% of the total annual energy flux is 10–20 days, about 10% of energy is contained in the 100 calmest days, while 50% of the annual energy flux arrives during the 100 days with strongest waves in the entire study area. The typical height of waves that provide the largest contribution to wave energy is about 1–1.5 m in the very north, around 1 m near the equator, gradually increases to the South and reaches 3.5–4 m on the shores of southern Chile. The associated wave periods are about 10 s in the entire study area. The wave energy flux has been almost constant over the 63 years near the equator but has increased at a rate up to 0.6 kW/m per year in the nearshore of Chile. For the evaluated time scales in coastal areas of South America, the interchange of El Niño and La Niña does not have detectable impact on the wave energy resource. • Wave energy resource rapidly increases along the Pacific coast from Panama to Chile. • This resource is ∼2 kW/m near Panama and up to 80 kW/m near the Drake Passage. • Swells predominate to the north of latitude 32°S and wind-seas to the south of 44°S. • Period of waves with largest energy resource is ∼10 s in the entire study area. • El Niño and La Niña phases insignificantly influence wave energy resource for the analysed scales. [ABSTRACT FROM AUTHOR]

• An AI model was applied in the spatiotemporal wave forecast with only wind inputs. • The proposed model has an efficient structure, outperforming popular ConvLSTM model. • The AI model achieve high accuracy against buoy data, even compared with ERA5. The forecast of ocean waves relies mostly on complex dynamic-based models, which are expensive in computation and demanding in professional skills to run. Diverse deep learning methods have been proposed to tackle this problem, yet the architecture of Transformer (i.e., the self-attention) was seldom tested for such a learning problem. To bridge this gap, we apply a state-of-the-art spatiotemporal attention network, the EarthFormer, and apply it for wave forecasting in the northwestern Pacific. To train and validate the EarthFormer, the fifth-generation atmospheric reanalysis dataset (ERA5) from the European Centre for Medium-Range Weather Forecast product with hourly resolution was adopted, with the sequence of wind as the input and the three key variables (i.e., significance wave height, mean wave period, and mean wave direction) of ocean waves as the output. The prediction can generate accurate wave forecasts up to 12 h ahead, with considerably low root-mean-squared error (RMSE). Overall, the predicted waves resulted in RMSE for the significance wave height of 0.22 m, for the mean wave period of 0.68 s, and for the mean wave direction of 0.28 rad. These wave height and wave period values are ∼13 % and ∼10 % of corresponding spatiotemporal mean values. The EarthFormer outperformed a popular spatiotemporal forecast network, the ConvLSTM, in our problem. For site-wise forecasts against buoy observations near Taiwan, the EarthFormer forecast also presents considerably high accuracy comparable to the ERA5 forecasts. This method can therefore provide an accurate and prompt way to forecast the large-scale distribution of waves to better model the marine dynamic and its climate effects, which could have a high potential for disaster prevention and climate modeling. [ABSTRACT FROM AUTHOR]

The Eastern Tropical and South-Eastern Pacific region is of global biodiversity importance. At COP26, the governments of Costa Rica, Panama, Colombia, and Ecuador committed to the expansion of existing MPAs to create a new Mega MPA, safeguarding the Eastern Tropical Pacific Marine Corridor. It offers a profound step forward in conservation efforts but is not specifically designed to protect against the more diffuse anthropogenic threats, such as plastic pollution. We combine published data with our own unpublished records to assess the abundance and distribution of plastic pollution in the region. Macro- and microplastic concentrations varied markedly and were not significantly different when comparing areas inside and outside existing MPA boundaries. These findings highlight the diffuse and complex nature of plastic pollution and its ubiquitous presence across MPA boundaries. Understanding the sources and drivers of plastic pollution in the region is key to developing effective solutions. • Analysis of 430 sites to assess plastic pollution in ET/SE Pacific. • No significant difference in plastic levels inside/outside of Marine Protected Areas. • New Mega MPA will not protect against ingress by plastic pollution. • Imperative to clearly establish sources and drivers of plastic pollution in region. [ABSTRACT FROM AUTHOR]

The dominant mode of the Indian Ocean variability can be impacted by changes in the background state (multidecadal timescale) of the subsurface heat content. The multidecadal variability of subsurface ocean heat content (sub-OHC) in the Indian Ocean is examined using four reanalysis products from 1958 to 2017. The analysis reveals a meridional basin-wide dipole mode in the subsurface OHC until the late 1980s, followed by the mode embedded in the uniform basin-wide patterns. These patterns are also observed in the trends of thermocline and sea surface height. The observed patterns in the Indian Ocean are explained by two distinct mechanisms. Firstly, the multidecadal variability of dipole patterns over the Indian Ocean is influenced by local wind forcing. Wind stress trends and Ekman pumping velocity trends favor downwelling (upwelling) in the off-equatorial southern Indian Ocean region, leading to thermocline depth deepening (shallowing) during 1958–1975 and 1976–1987, respectively. Secondly, the combined effect of heat transport from the western Pacific through Indonesian Through Flow and local wind forcing accounts for the basin-wide cooling and warming trends observed during 1988–2000, and 2001–2014, respectively. • Study shows a presence of meridional dipole in the subsurface OHC until late 1980s, followed by uniform basin-wide patterns. • The meridional diploe mode is embedded in the basin-wide pattern, it is insignificant due to the dominancy of ITF transport. • The meridional dipole is purely local wind driven and the basin-wide patterns are the combined effect of ITF and local wind. [ABSTRACT FROM AUTHOR]

Due to their unusual life cycle that includes parasitic larval and free living adult stages, gnathiid isopods are typically overlooked in biodiversity surveys, even those that focus on parasites. While the Philippines sits within the region of highest marine biodiversity in the world, the coral triangle, no gnathiid species have been identified or described from that region. Here we present the first records of two gnathiid species collected from the Visayas, central Philippines: Gnathia malaysiensis Müller, 1993, previously described from Malaysia, and G. camuripenis Tanaka, 2004, previously described from southern Japan. This paper provides detailed morphological redescriptions, drawings and scanning electron microscope images as well as the first molecular characterisation of both species, Furthermore, a summary of the Central-Indo Pacific Gnathia species is provided. [Display omitted] • Morphological description of two gnathiid species collected from the central Philippines, along with molecular data, are presented. • Gnathia malaysiensis was previously described from Malaysia and G. camuripenis was previously described from southern Japan. • Although the Philippines is in the highly biodiverse coral triangle, this is the first gnathiid description from this region. • The wide geographic range of G. camuripenis suggests dispersal via large, highly mobile fishes, and/or tropical cyclones. [ABSTRACT FROM AUTHOR]

The water temperature at 100–300 m depth layer impact on bigeye tuna distribution has been studied from data collected by 15 fishery survey vessels, surveying every day, in the Equatorial Pacific Ocean from February to March and June to September 2010. The in situ ocean temperature measurements at four depths (100, 150, 200, and 300 m), satellite data and TAO/TRITON moored buoy data were also augmented in this study. The results reveal stereoscopic temperature factors for the prediction of tuna fishing ground: horizontal temperature gradient (HTG), vertical temperature gradient (VTG) in the 100–300 m layer. Maximal catches were observed where (1) vertically there has a strong subsurface temperature front in the 150–200 m layer, with horizontal temperature gradient up to near 0.020 °C/km; (2) there have vertical temperature gradient between −0.088 and −0.066 °C/m. Meanwhile, the monthly tuna fishery catches decrease with the synchronized reduction of 20 °C isotherm depth in the ocean. [ABSTRACT FROM AUTHOR]

Massive reef-building Porites corals are commonly studied to obtain long-term reconstructions of past sea surface temperature (SST) using temperature-sensitive elemental proxies, such as Sr/Ca or Li/Mg ratios. Most recently, a multi-proxy approach combining these two ratios (e.g. D'Olivo et al., 2018) and the Sr U method (DeCarlo et al., 2016) have proved to be more robust to reconstruct paleo-temperatures. To date, no study has been carried out on the application of these new approaches on the Diploastrea heliopora coral, another massive reef-building genus that can potentially provide longer temperature records. Moreover, only a few studies have assessed coral SST calibrations at the scale of the Indo-Pacific basin and compared SST reconstructions obtained from two massive coral genera from the same site. In this study, we investigated the elemental composition of the topmost portion of 34 modern tropical Porites and 6 Diploastrea colonies collected during the Tara Pacific expedition (2016–2018) from various hydrological contexts in the Pacific Ocean. We derived and discussed annual Sr/Ca, Li/Mg, combined Sr/Ca-Li/Mg and Sr/Ca-Li/Ca-Mg/Ca and Sr U vs. SST calibrations as well as potential intra-colonial and genus specific effects and evaluated the use of these basin-wide calibration equations. Overall, multi-ratio and multi-genera SST calibrations perform better than single-ratio calibrations and seem to improve temperature reconstructions. These new SST calibrations were applied to two colonies of Porites and Diploastrea collected from the same site in the North-West of the Palau archipelago located in the western Pacific Ocean to evaluate the applicability of universal calibrations based on different proxies and their combination. Coral-based SST records spanning the last 141 years show decadal changes and recent warming episodes that are related to major El Niño Southern Oscillation events. However, differences in reconstruction remain between both genera in the long-term trends, amplitudes, and absolute temperatures, depending on which genus or temperature proxy is considered. [ABSTRACT FROM AUTHOR]

Based on satellite and in situ data and larval fish distributions obtained from two cruises during April 2012 (cold period) and September 2016 (warm period), larval fish habitats were analyzed in relation to the water masses that converge at the entrance of the Gulf of California. The distribution of environmental variables and the ocean upper layer water masses showed a clear-cut seasonal contrast. During April 2012, the Gulf of California Water extended southward to ∼21oN, while in September 2016, the Transitional Water expanded northward to ∼23oN to dominate the entrance of the Gulf of California as the Gulf of California Water retreated to the interior gulf. In addition, mesoscale eddies were frequently observed in both periods, mostly cyclonic in April 2012, and anticyclonic in September 2016. Multivariate analyses defined two larval fish habitats in each period: North and South of a boundary between 22 and 22.5oN. The larval structure of the North larval fish habitat varied in both composition and abundance between periods, although the dominant species in both periods were Vinciguerria lucetia above the thermocline and Diogenichthys laternatus in the layer beneath the thermocline. These species had a higher abundance in April 2012 than in September 2016. The South larval fish habitats also had differences in their larval structures in the two periods, but Bregmaceros bathymaster was the dominant species, with the highest abundance in April 2012. The definition of the larval fish habitats and their changes in structure were associated with the seasonal contrast of the water masses, but the limits of the larval fish habitats were modulated by the mesoscale structures. The spawning of most species is seasonally controlled, but the dominant ones showed signs of resilience to environmental changes. This study displayed the influence of two different environmental scales on the fish larvae community, which might be a pattern in other regions of water mass convergence. • Upper layer water masses converge at the entrance of the Gulf of California. • Gulf of California Water (cold period) and Transitional Water (warm) vary seasonally. • Water mass borders define North and South larval fish habitats in both periods. • Eddies limit larval fish habitats, cyclonic in the cold period and anticyclonic in warm period. • Dominant species (mesopelagic) in both periods show tolerance to seasonal changes. [ABSTRACT FROM AUTHOR]

Estimation of the ocean subsurface thermal structure (OSTS) is important for understanding thermodynamic processes and climate variability. In the present study, a novel multi-model ensemble machine learning (Ensemble-ML) model is developed to retrieve subsurface thermal structure in the Pacific Ocean by integrating sea surface data with Argo observations. The Ensemble-ML model integrates four individual machine learning models to enhance estimation accuracy and reliability. Our results exhibit good agreement between the satellite sea surface temperature (SST) and sea surface salinity (SSS) data and Argo observations, providing validation for the utilization of these datasets in the Ensemble-ML model. The Ensemble-ML model exhibits better performance compared to individual machine learning models, with an average root mean square error (RMSE) of 0.3273 °C and an average coefficient of determination (R²) of 0.9905. Notably, incorporating geographical information as input variables enhance model performance, emphasizing the importance of considering spatial context in OSTS estimation. The Ensemble-ML model accurately captures the spatial distribution of OSTS across depths and seasons in the Pacific Ocean, effectively reproducing critical temperature features while maintaining strong agreement with Argo observations. Nevertheless, its performance shows relative weakness within the thermocline layer and the equatorial Pacific region (spanning from 10°S to 10°N latitude), which are characterized by complex circulation systems. Despite these challenges, the Ensemble-ML model effectively reproduces the spatial distribution of OSTS of the Pacific Ocean. This indicates the potential of machine learning models, particularly ensemble models, for enhancing OSTS estimation in the Pacific Ocean and other regions, offering valuable insights for future research and applications in physical oceanography. • A novel multi-model ensemble machine learning (Ensemble-ML) model was developed to estimate the ocean subsurface thermal structure (OSTS). • The Ensemble-ML approach consistently outperforms individual machine learning models in accuracy and reliability. • The Ensemble-ML model effectively estimate OSTS in the Pacific Ocean using sea surface data. [ABSTRACT FROM AUTHOR]

A 2.75 m long core was recovered from La Joya lagoon at the southern Pacific coast of Mexico. The base of the core gave an age of ca. 5600 a BP. The AMS 14C dating results indicate a continuously depositional history over the past 5600 years with varied sedimentation rates of 0.022–0.08 cm/yr. Sediment samples were analyzed for pollen, diatoms, loss on ignition (LOI), magnetic susceptibility and elemental analysis, to study the environmental and marine changes ocurred during the Holocene in the study site of the Pacific coast. Our data provided indications of the paleoenviromental changes in the study site from the south Pacific coast of México: a complete marine environment from ca. 5600 to ca. 3200 a BP; a transitional lagoon from ca. 3200 to 1100 a BP; and followed by a shift toward a close lagoon with fresh water during the last 1100 years. The pollen data (the presence of pollen from Cucurbitaceae and secondary taxa related to disturbed vegetation) of La Joya record show evidence of agricultural activities and Human occupation in the study area might exist 5000 a BP. [ABSTRACT FROM AUTHOR]

Early Paleogene neodymium (Nd) isotopic reconstructions of ocean circulation in the Pacific suggest a bipolar mode of overturning circulation characterized by convection of deep-water masses from 70 to at least 40 Ma. This mode is fundamentally different from the "sluggish, diffusive" mode that characterizes the modern North Pacific. Therefore, major reorganization of Pacific circulation must have occurred between 40 Ma and the modern. To investigate the potential timing of such a reorganization, we present new Nd isotope data from drill sites spanning 40 to 10 Ma. Here, we use Nd isotopic analyses to identify the sources of dissolved Nd to the Pacific in order to evaluate the application of the Nd proxy for ancient water mass composition. We combine analyses of fossil fish debris, sequentially leached oxide coatings and leach residues to further refine our understanding of Nd marine geochemical cycling and to contribute new constraints on the paleoceanographic history of the Pacific. Overall, these data support previous interpretations of the convection of deep water in the Pacific sector of the Southern Ocean and surface-ventilated North Pacific Deep Water formation from ∼70 to 40 Ma. The new Nd isotope data suggest a gradual transition between 36 and 25 Ma, a time period characterized by global cooling. This transition consists of a change from North Pacific Nd isotopic signatures controlled by convection and water mass mixing to values heavily influenced by overprinting from other sources of Nd to the deep Pacific. Such a transition is consistent with a change in overturning circulation from a "Paleogene mode" to a mode dominated by sluggish diffusive mixing. After 25 Ma the data indicate a significant contribution of radiogenic dissolved Nd to the deep waters of the North Pacific. The most likely source of radiogenic dissolved Nd would have been labile volcanic ash that altered the composition of the water mass as it slowly advected through the North Pacific. A slowing of overturning circulation in the North Pacific could have resulted in diminished poleward heat transport, increasing equator to pole thermal gradients and contributing to a cooling global climate. • We present Nd isotope data from deep sea sediment in the Pacific from 40-10 Ma. • Slowing deep water formation at 36 Ma results in overprinting of Nd in North Pacific. • North Pacific Deep Water transitions to modern mode of circulation by 25 Ma. • Shut down of North Pacific Deep Water is associated with cooling climate after 36 Ma. • The switch from bipolar to modern Pacific deep water formation occurred from 36-25 Ma. [ABSTRACT FROM AUTHOR]

A floating plastic monitoring program was conducted for two years on a weekly basis in Banderas Bay, Mexico. A total of 94 samples were collected from May 2016 to April 2018 in the southern part of the bay. Half (57%) of them contained plastic debris; 79% of it being <5 mm in length. Polypropylene and Polyethylene were the most abundant polymers, accounting for 45% and 43% of the plastic pieces (pp), respectively. The highest abundance of plastic pieces was found in July 2016, with a maximum of 0.3 pp/m3 found in one sample. The amount of floating plastics was significantly higher in the hurricane season compared to the dry season (p < 0.001). This suggests that rainfall may play a significant role in the offload of plastics from land-based sources into the bay. Unlabelled Image • Two years of floating plastic monitoring was conducted from 2016 to 2018. • Microplastics (<5 mm) accounted for 79% of collected plastic pieces. • A significant seasonal signal was detected in the two years of monitoring. • The mean abundance is lower than most of the floating plastic debris studies. [ABSTRACT FROM AUTHOR]

This paper presents isotopic compositions (δ15N and Δ17O values) of atmospheric particulate nitrate (p-NO 3 −) collected over the Pacific Ocean between 40°S and 68°N on two cruises using the Research Vessel Hakuho Maru. Six marine regions over the Pacific Ocean were categorized using backward trajectory analysis, and various ion concentrations were employed to assess the dominance of anthropogenic or non-anthropogenic sources. The δ15N(p-NO 3 −) values ranged from −15.4‰ to 2.5‰ over the Pacific Ocean between 40°S and 68°N. The range of the source δ15N(NO x) values were calculated for each sample based on isotopic exchange/fractionation during oxidation from NO x (NO and NO 2) to HNO 3 , and a range of −14.1 to 6.9‰ was yielded over the Pacific Ocean. Compared to other regions, extremely low δ15N(NO x) values of −14.1‰ to −7.3‰ were found over the equatorial Pacific, and such values cannot be matched using conventional NO x apportionment. Emissions of specific oceanic nitrogen emissions of NH 3 and alkyl nitrate are thus proposed for the equatorial Pacific. Results demonstrate the importance of the nitrogen recycling process between the ocean and lower atmosphere in the equatorial Pacific. Δ17O(p-NO 3 −) values and light flux were found to be generally well-correlated in most Pacific Ocean regions, and this result is consistent with the importance of photolysis for OH radical concentrations relative to the contribution of O 3 in producing HNO 3 from NO x. In contrast, Δ17O(p-NO 3 −) values for the eastern North Pacific region were higher than in other regions with similar light fluxes, which implies a contribution from halogens to p-NO 3 − formation. • We present data sets of δ15N and Δ17O of atmospheric p-NO 3 − over Pacific Ocean. • The low δ15N in equatorial Pacific suggest N recycle between marine and atmosphere. • The high Δ17O indicate NO 3 − formation by halogen in the central North Pacific. [ABSTRACT FROM AUTHOR]

We report dissolved concentrations of the long-lived radioisotope 236U measured in the water column along the 2013 US GEOTRACES Eastern Pacific Zonal Transect (GP16). This transect followed a 10–15°S line from Manta, Ecuador, to Papeete, Haiti, French Polynesia, crossing the southern East Pacific Rise, intercepting one of the largest hydrothermal plumes as well as a productivity gradient, which includes the upwelling zone and associated low oxygen waters offshore from Peru and the oligotrophic sub-tropical gyre. Accelerator Mass Spectrometry was used to measure dissolved seawater 236U concentrations as low as 1 × 103 atom kg−1, which are among the lowest levels reported to date. Differences in upper water column 236U distributions from east to west are a result of variable contributions from different surface and intermediate waters encountered along the transect. The distribution of 236U, both in depth and geographically, provides complementary information to that obtained from Δ14C and helium isotopes, demonstrating that 236U concentrations are diagnostic in the identification of and contributions from the different deep and bottom water masses encountered along the EPZT (Jenkins et al., 2017). For example, we observe minimum 236U concentrations along the EPZT between 2000 and 3000 m that are consistent with contributions attributed to Pacific Deep Water. We also observe increases in 236U below 3000 m at the eastern and western termini of the EPZT. This is consistent with contributions associated with Antarctic Bottom Water and Lower Circumpolar Deep Water. Our results indicate that 236U may be used in conjunction with Δ14C and 3He isotopes as an additional tool with which to identify and resolve contributions from different water masses in the Pacific Ocean. This article is part of a special issue entitled: "Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyond" - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González. Unlabelled Image • 236U inventory in EPZT is one order of magnitude lower than in North Pacific. • 236U anthropogenic contribution at the EPZT is due to global fallout contribution. • AMS was used to measure dissolved 236U concentrations, which are among the lowest 236U values reported for seawater. • Lowest 236U concentrations were 1 × 103 at kg−1, measured between 2000 and 3000 m. • 236U distributions were used to identify deep and bottom water masses in EPZT. [ABSTRACT FROM AUTHOR]

Highlights • Vessel effects should be accounted for in the catch rate standardization procedure. • Area-weighting was more important than vessel effects in the standardization. • The nominal index overestimated the abundance trend than did the standardized index. • The spatiotemporal modeling of catch rate data improved the stock assessment. Abstract Spatiotemporal models of catch rate data are used in fisheries science to understand the spatiotemporal dynamics of a fishery and, more importantly, to produce a standardized index of relative abundance for stock assessment models. Here, we apply a spatiotemporal delta-generalized linear mixed model to catch rate data collected from the dolphin-associated purse-seine fishery for yellowfin tuna (Thunnus albacares) in the eastern Pacific Ocean during 1975–2016. Results show that the density of yellowfin tuna had both pronounced spatial variation across the eastern Pacific Ocean and spatiotemporal variation at time scales from quarterly to decadal. In comparison to the index of relative abundance standardized via the spatiotemporal approach, that computed via the nominal approach, which is currently used in the stock assessment, under- and over-estimates initial and terminal abundances, respectively, by as much as 50% or more. The standardized index represents an improvement over the nominal index because the spatiotemporal approach imputes population density in unfished areas to obtain an area-weighted index and accounts for vessel-specific differences in fishing efficiency. The importance of area-weighting for index standardization is highlighted by the fact that ignoring it has a greater effect on the abundance index than does ignoring differences in fishing efficiency among vessels. The stock assessment model that includes standardized indices has significantly larger log-likelihood and reduced pattern in residuals than the one that includes nominal indices, suggesting that replacing nominal indices with indices from a spatiotemporal model can improve the stock assessment for yellowfin tuna in the eastern Pacific Ocean. [ABSTRACT FROM AUTHOR]

Abstract Although the cycling of chromium (Cr) in the ocean may have direct implications on the Cr isotope system's application as a paleo-redox proxy, little seawater Cr isotope data has been published. This may be partly due to the analytical challenges associated with the preconcentration and the purification of the nano-molar trace metal Cr from the seawater matrix. Here, we present a reliable method for the determination of accurate and precise 53Cr/52Cr isotope ratios of total chromium (=Cr(III) + Cr(VI)) in seawater, which could be modified to be redox species-specific. Seawater acidification induces the slow conversion of Cr(VI) to Cr(III). Total Cr of the sample and an equilibrated 50Cr-54Cr double spike is preconcentrated as Cr(III) using Mg(OH) 2 coprecipitation. Cr captured by the Mg(OH) 2 pellet is oxidized to Cr(VI) using (NH 4) 2 S 2 O 8 under carefully controlled pH, temperature and time settings, in order to avoid H 2 O 2 generation and to control sulfur speciation. Taking advantage of the differing charges of Cr(III) and Cr(VI), three AG 1-X8 columns separate Cr from the salt matrix and isobaric interferences V, Ti, and Fe (column 1), sulfur polyatomic interferences (column 2), and Fe traces (column 3). Analysis is conducted on a MC-ICP-MS IsoProbe featuring a hexapole collision cell in low resolution mode. When pure solutions of SRM 979 are processed via this low blank method (~0.017 nmol of Cr), δ53Cr w.r.t. SRM 979 = +0.02 ± 0.06‰ (±2 SD) is obtained (n = 10). Using this technique, the first full water column profile of Cr isotope ratios at a station in the Pacific Ocean (SAFe station, 30°N 140°W) was generated and demonstrates high oceanographic consistency. This article is part of a special issue entitled: "Cycles of trace elements and isotopes in the ocean – GEOTRACES and beyond" - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Eastern Liaoyuan Accretionary Belt extends eastwards over the Dunhua-Mishan Fault. • Dunhua-Mishan Fault shows a 170 km sinistral displacement taking place in the late Mesozoic. • Tan-Lu Fault Zone has a total sinistral displacement of 205 km in NE China. • Dunhua-Mishan Fault records more strike-slip movement than the Yilan-Yitong Fault. Abstract The NE- to NNE-striking, continental-scale Tan–Lu Fault Zone (TLFZ) in NE China is subdivided into the ∼900 km long Yilan–Yitong Fault (YYF) in the west and the ∼1000 km long Dunhua–Mishan Fault (DMF) in the east. Both faults record sinistral displacement during the earliest Cretaceous, leading to an obvious offset of the boundary between the Liaoyuan Accretionary Belt (LAB) and the North China Craton (NCC). Previous studies have demonstrated that the LAB in the south of the eastern Central Asian Orogenic Belt (CAOB) extends eastwards into an area between the YYF and the DMF. The boundaries between the LAB and NCC indicate a 35 km sinistral displacement upon the YYF. However, it remains unclear whether the LAB extends to the east of the DMF, and the amount of sinistral displacement on the DMF is poorly constrained. Here we present lithological observations and U–Pb and Hf isotopic data from zircon to constrain the age and position of the LAB to the east of the DMF. The data indicate an eastward extension of the LAB across the DMF, suggesting the continuous presence of the LAB east of the TLFZ in NE China. The U–Pb ages, ε Hf (t) values, and two-stage model ages of zircons from the study area constrain the boundary between the LAB and NCC to an extension of the NE-dipping Chifeng–Kaiyuan Fault to the east of the DMF. The geological boundaries on both sides of the DMF indicate a 170 km sinistral displacement along the fault. Thus, the TLFZ has a total sinistral displacement of 205 km in NE China. The eastern branch of the TLFZ records significantly more movement due to its proximity to the Pacific Ocean, where subduction of oceanic crust might have caused sinistral faulting along the TLFZ. [ABSTRACT FROM AUTHOR]

Abstract Ferromanganese nodules have long been considered an attractive source for Mn, Co, Ni and Cu and, potentially, for the rare earth elements and yttrium (REY). Sixteen exploration contracts have recently been granted for the Clarion-Clipperton Fracture Zone (CCFZ) in the eastern equatorial Pacific and, because of concern about the environmental impacts of seafloor mining, some parts of the CCFZ have been designated 'Areas of Particular Environmental Interest' (APEI) from which mining will be excluded. As the APEIs were selected based on surface ocean characteristics and seafloor topography, estimated from satellite altimetry, the abundance and composition of nodules in these areas are unknown, and as a result their relevance as an intended baseline for mining disturbance has not been demonstrated. To fill this gap, we have undertaken a detailed study of the chemical composition of nodules and seafloor sediments in the UK Contract area in the CCFZ and its closest APEI, APEI-6. There are distinct differences between the two sites: nodules from the UK Contract area are larger (10–15 cm in diameter) compared to those from APEI-6 (2–4 cm diameter), and they have faster growth rates (~11 vs ~3 mm/Ma). Nodules from APEI-6 have, on average, higher contents of Fe (7.2 vs. 5.7 wt%), Co (0.28 vs. 0.13 wt%) and total REY (1120 vs. 715 ppm) relative to those from the UK Contract area. Analyses of individual growth layers reveal that nodules from the UK Contract area contain a greater proportion of Mn-rich phases that are also enriched in Ni and Cu. Although pore waters in the uppermost sediments are oxygen replete today, these layers likely precipitated from suboxic sediment pore waters indicating that the supply of organic material to the sediments in this area has been higher in the past. Sediments from the UK Contract area, in turn, have higher Mn/Al ratios compared to sediments from APEI-6 and have a higher proportion of Mn in easily-reducible phases. Nodules from APEI-6 have a greater proportion of Fe-rich layers that are also enriched in Co and the REY, and likely precipitated from seawater. These differences in the chemical composition of nodules from the UK Contract area and APEI-6, as well as differences in the oxygen penetration depth in the sediments, mean that APEI-6 does not provide a relevant geochemical baseline for mining disturbance in the UK Contract area, or for many other contract areas within the CCFZ. Graphical abstract Unlabelled Image Highlights • Differences in texture and geochemistry within individual nodules • Mode of nodule formation can change over time. • Changes in nodule chemistry and density occur over small length scales (<500 km). • Single geochemical baseline for assessing impacts of nodule mining not possible [ABSTRACT FROM AUTHOR]

Abstract Plastics have been accumulated offshore and in the deep oceans at an unprecedented scale. Microbial communities have colonized the plastisphere, which has become a reservoir for both antibiotic and metal resistance genes (ARGs and MRGs). This is the first analysis of the diversity, abundance, and co-occurrence of ARGs and MRGs, and their relationships within the microbial community, using metagenomic data of plastic particles observed in the North Pacific Gyre obtained from the National Centre for Biotechnology Information Sequence Read Archive database. The abundance of ARGs and MRGs in microbial communities on the plastics were in the ranges 7.07 × 10−4–1.21 × 10−2 and 5.51 × 10−3–4.82 × 10−2 copies per 16S rRNA, respectively. Both the Shannon-Wiener indices and richness of ARGs and MRGs in plastics microbiota were significantly greater than those of ARGs and MRGs in seawater microbiota in the North Pacific Gyre via one-way analysis of variance. Multidrug resistance genes and multi-metal resistance genes were the main classes of genes detected in plastic microbiota. There were no significant differences in the abundance or diversity of ARGs and MRGs between macroplastics biota and microplastics biota, indicating that particle size had no effect on resistance genes. Procrustes analysis suggested that microbial community composition was the determining factor of the ARG profile but not for MRG. Some ARGs and MRGs had a higher incidence of non-random co-occurrence, suggesting that the co-effects of selection for antibiotic or metal resistance are important factors influencing the resistome of the microbiota on the plastic particles. Graphical abstract Unlabelled Image Highlights • Plastic size does not influence the abundance and diversity of resistance genes. • Metal resistance genes had higher abundances than antibiotic resistance genes. • Plastics are a reservoir for metal resistance genes and antibiotic resistance genes. • Bacterial community driving ARG composition but not for MRG profile • Flavobacteriaceae family bacteria are potential host for ARGs and MRGs. [ABSTRACT FROM AUTHOR]

Abstract To examine how the mantle lithosphere stabilises continents, we present a synthesis of the mantle beneath Zealandia in the SW Pacific Ocean. Zealandia, Earth's "8th continent", occurs over 4.9 M km2 and comprises a fore-arc, arc and back-arc fragment rifted from the Australia–Antarctica Gondwana margin 85 Myr ago. The oldest extant crust is ∼500 Ma and the majority is Permian–Jurassic. Peridotitic rocks from most known locations reveal the underpinning mantle to comprise regional domains varying from refractory (Al 2 O 3 < 1 wt%, olivine Mg# > 92, spinel Cr# up to 80, Pt/Ir < 1) to moderately depleted (Al 2 O 3 = 2–4 wt%, olivine Mg# ∼90.5, spinel Cr# < ∼60). There is no systematic distribution of these domains relative to the former arc configuration and some refractory domains underlie crust that is largely devoid of magmatic rocks. Re-depletion Os model ages have no correlation with depletion indices but do have a distribution that is very similar to global convecting mantle. Whole rock, mineral and isotopic data are interpreted to show that the Zealandia mantle lithosphere was constructed from isotopically heterogeneous convecting mantle fragments swept into the sub-arc environment, amalgamated, and variably re-melted under low-P hydrous conditions. The paucity of mafic melt volumes in most of the overlying crust that could relate to the depleted domains requires melting to have been followed by lateral accretion either during subduction or slab rollback. Recent Australia–Pacific convergence has thickened portions of the Zealandia mantle to >160 km. Zealandia shows that the generation of refractory and/or thick continental lithosphere is not restricted to the Archean. Since Archean cratons also commonly display crust–mantle age decoupling, contain spinel peridotites with extreme Cr# numbers that require low-P hydrous melting, and often have a paucity of mafic melts relative to the extreme depletion indicated by their peridotitic roots, they too may – in part – be compilations of peridotite shallowly melted and then laterally accreted at subduction margins. Highlights • Peridotites from a Cretaceous fore-arc, arc and back-arc fragment rifted of Gondwana. • Zealandia mantle constructed from convecting mantle fragments in a sub-arc environment. • Zealandia mantle variably re-melted under low-P hydrous conditions and laterally accreted. • Similarities to the formation of the Zealandia mantle with the mantle beneath Archean cratons. [ABSTRACT FROM AUTHOR]

Abstract The Manihiki Plateau, a Large Igneous Province (LIP) in the western Pacific, has been proposed to be emplaced as part of the "Greater Ontong Java Event" during the early Cretaceous. Shortly after its formation, the Manihiki Plateau fragmented into multiple sub-provinces. Plate tectonic reconstructions ignore this fragmentation, treating the Manihiki Plateau as a single crustal block. By analyzing two seismic refraction/wide-angle reflection profiles crossing the two largest sub-provinces of the Manihiki Plateau, we provide new insight into their deep crustal structure and magmatic evolution. Our data indicate that the High Plateau and the Western Plateaus were emplaced as a single unit during an initial phase of massive magmatic activity, but later magmatic stages altered the individual sub-provinces considerably. The High Plateau has a crustal thickness of 20 km and its P-wave velocity distribution is comparable to previously surveyed oceanic LIPs. Strong secondary magmatic phases are visible by eruptive centers and former magmatic pathways in the middle and lower crust. The Western Plateaus, which have a crustal thickness decreasing gradually from 17.3 km (East) to 9.2 km (West), experienced smaller amounts of magmatism mainly along fault zones and on local seamounts. Therefore, we propose a distinct development of the two main sub-provinces of the Manihiki Plateau after their initial joint emplacement. The High Plateau experienced voluminous multi-phase magmatic accretion and extrusion, whereas the thinner Western Plateaus exhibit only relatively minor magmatic growth. Such a large difference in the evolution process has not been reported from any other oceanic LIP so far. Highlights • First comprehensive modelling of the crust and upper mantle of the Manihiki Plateau • Multiphase emplacement of a Large Igneous Province • Interplay of tectonism and magmatism on different sub-provinces • Distinct individual evolution of sub-provinces of the Manihiki Plateau [ABSTRACT FROM AUTHOR]

Highlights • The past PDSI since 1568 was reconstructed for the eastern region of the Silk Road. • The dry periods reconstructed here were well-documented historical drought events. • When ENSO and PDO were in phase, PDSI tended to be below or above normal more often. • Influence of the Pacific Ocean on drought variability was affected by global warming. Abstract Drought variability from 1568 to 2014 was presented for the eastern region of the Silk Road by using five tree-ring chronologies and an optimal information extraction method (i.e., one of the composite-plus-scale methods). The inspection results of the split calibration-verification procedure for the transfer functions showed that the reconstructed Palmer drought severity index (PDSI) was credible throughout the entire time interval. During the past 447 years, there were seven dry periods (1616–1622, 1629–1645, 1682–1730, 1760–1778, 1805–1884, 1919–1933 and 1990–2009) and seven wet periods (1573–1615, 1623–1628, 1646–1681, 1731–1759, 1779–1804, 1885–1918 and 1934–1989). The dry periods were well-documented historical drought events. Significant interannual periods of 2.1–3.8 years and interdecadal cycles of 17.1, 18.3, 23.8, 42.7, 51.3 and 73.0 years were identified via the multitaper method for spectral analysis. Similar patterns of drought fluctuations were found in the records of the drought/flood index and other drought reconstructions. By comparing the reconstructed PDSI with the El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) at the multidecadal scale, it was discovered that when ENSO and PDO were in phase (i.e., high-PDO/warm-ENSO phase or low-PDO/cold-ENSO phase), the study region was dry or wet more often, respectively, especially before 1850. The influence of ENSO and PDO on the decadal variability of drought has been affected by global warming. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Mikabu greenstones in SW Japan are fragments of accreted oceanic plateau. • Zircon U-Pb ages from the Mikabu greenstones show an igneous age of 155 Ma. • Zircon trace elements suggest depleted source mantle for the Mikabu protolith. • The Mikabu greenstones were parts of Jurassic oceanic plateau like Shatsky Rise. Abstract The Mikabu greenstones form accreted fragments of an ancient oceanic plateau, which are currently incorporated within the Cretaceous high P/T-type Sanbagawa metamorphic belt in SW Japan. Previous geological and petrological studies indicate that protoliths of the Mikabu greenstones were mafic/ultramafic volcano-plutonic rocks of oceanic plateau and/or islands. Despite their rock assemblage and metamorphic nature, their protolith age has been poorly constrained. By measuring U-Pb age of igneous zircon grains using LA-ICPMS, this study identified for the first time a Late Jurassic age for the protoliths of the Mikabu greenstones in the eastern Kii Peninsula (the Shurei complex). With an overlap within 2-sigma error, measured U-Pb ages of zircon grains have a weighted mean age of 154.6 ± 1.6 Ma (the Kimmeridgian, Late Jurassic), which is slightly younger than the radiolarian ages (Middle Jurassic) of deep-sea pelagic cherts associated with the Mikabu greenstones. This age difference indicates that mafic magmas intruded pelagic deep-sea sediments to form a volcanic edifice onto the pre-existing oceanic lithosphere. New measurements of trace element composition of the dated zircon grains further confirmed that the dated zircon grains are more similar to those in oceanic crusts rather than in continental crusts. In addition, the trace element composition suggests that the host mafic magma of the zircon grains was derived from depleted mantle similar to the mid-oceanic ridge-type source, rather than fertile mantle source like Hawaii and Iceland. On the basis of the common occurrence of similar mafic rocks from the Shatsky Rise in the modern NW Pacific Ocean, we conclude that the protoliths of the Mikabu greenstones had formed a part of an oceanic plateau/island, which was generated by the Late Jurassic intra-plate mafic magmatism in ancient mid-Pacific, probably together with the Shatzky Rise. [ABSTRACT FROM AUTHOR]

Abstract The ongoing public concern about the Fukushima nuclear accident's real consequences determined us to start a new Accelerator Mass Spectrometry study of 129I concentrations in the North Pacific Ocean. Our results show that currently, the radioiodine 129 concentrations from coastal Japanese sea water samples are in the range of (0.9–1.6) × 108 atoms L−1. Higher 129I concentrations of 6.4 × 108 atoms L−1 have been found in the Tadami River, located close to the damaged nuclear reactors. For the North Pacific and all the way into the western shore line we found to have now much lower concentrations, with an average of 2.5 × 107 atoms L−1. Therefore, Fukushima and its vicinities remain an isolated area of nuclear pollution. [ABSTRACT FROM AUTHOR]

Abstract Environmental microplastics are widely documented in marine life and bioaccumulation may present risks to marine predators. Investigations of microplastics in marine mammals are increasing, though none have examined animals routinely consumed by humans. Here, we investigate microplastic exposure in the northern fur seal (Callorhinus ursinus), a species consumed by humans, using fecal material. We examined 44 feces (scat) at sites encompassing the seals' eastern Pacific range. Multiple contamination control measures were implemented, including field and laboratory controls. Fragments were the most common microplastic recovered, in 55% (24/44) of scat and no controls (range 1 to 86 fragments/scat, mean 16.6, sd 19.1). Microplastic fibers were recovered from 41% of scats (18/44), though some controls contained fibers confounding fiber results. Fecal analysis documented northern fur seal exposure to microplastics throughout their eastern Pacific range. Graphical abstract Unlabelled Image Highlights • Wild northern fur seals are exposed to microplastics throughout their U.S. range. • Over 50% of northern fur seal feces contained from 1 to 86 microplastic fragments. • Threats associated with microplastics are incompletely known. • Microplastic bioaccumulation in marine top predators represents an emerging risk. [ABSTRACT FROM AUTHOR]

Abstract Gelatinous zooplankton including jellyfishes, pyrosomes, and salps serve as important prey items for a number of marine species; however, relatively few studies have examined contaminant concentrations in these animals. Scyphozoans (Aurelia sp., Chrysaora colorata , C. fuscescens , and Phacellophora camtschatica) and Thaliaceans (Pyrosoma sp.) were collected from 2009 to 2011 from Monterey Bay National Marine Sanctuary and analyzed for total mercury and selenium concentrations. In general, mercury (0.0001–0.0016 μg/g wet weight) and selenium (0.009–0.304 μg/g wet weight) concentrations of the sampled organisms were low; however, the two Pyrosoma sp. had total mercury and selenium concentrations that were one order of magnitude higher than the Scyphozoans. There was a significant positive relationship between mercury and selenium concentrations in jellyfishes and pyrosomes, suggesting a potential detoxification mechanism in these lower trophic level organisms. This study provides evidence that trophic transfer of mercury and selenium likely occurs through ingestion of gelatinous prey. Highlights • Mercury and selenium concentrations were documented in jellyfishes and pyrosomes. • Mercury and selenium concentrations were highest in pyrosomes. • Mercury and selenium correlated in jellyfishes and pyrosomes. [ABSTRACT FROM AUTHOR]

Abstract The radial distribution of environmental pressure near the ground surface during typhoons is an initial input condition for height-resolving typhoon modeling widely used as a practical and relatively accurate method for rapid assessment of typhoon-induced natural hazards and wind-resistant design of structures. The radius to maximum wind speed R max and radial pressure distribution parameter β s , (usually named the Holland power exponent of atmospheric pressure) are two key pressure field parameters that fundamentally determine the parametric typhoon pressure field and collocated wind velocity field. Observations from the Joint Typhoon Warning Center (JTWC) show that R max follows a lognormal distribution and has strong correlation with central pressure difference Δ p s and typhoon center latitude ψ. However, it is still hard to satisfactorily reproduce the landing typhoon environmental pressure. By employing near-ground environmental pressure data involving several hundreds of meteorological stations distributed in coastline regions of the Northwest Pacific Ocean, evolution of typical environmental pressures during four strong typhoons, Khanun (0515), Wipha (0713), Krosa (0716) and Morakot (0908), have been recorded in Southeast China. Finally, a novel technique for modeling the radial surface pressure model is proposed utilizing an appropriate model for radius to maximum winds R max. The variation characteristics for directions, landfall states and probability distributions of β s are compared and discussed, and then probability correlations among β s and R max , Δ p s , ψ are fitted and validated, showing that the statistical correlation function model is obviously different from former formulations and is more suitable for rebuilding a wind velocity field, especially near the ground surface after typhoon landfalls along the southeast coastlines of China, which are typhoon-prone hazard regions during moving typhoons. Highlights • The general procedures for solving height-resolving typhoon boundary layer pressure and wind fields were summarized. • A novel technique for modeling the Holland surface pressure model was proposed by employing near-ground pressure data. • A couple of R max models was discussed before a statistical model for β s at sea level was developed. • A comparison of proposed β s model with former common-used models was conducted. [ABSTRACT FROM AUTHOR]

Abstract The segmented major Agua Blanca Fault is one of the largest geologically active faults in northern Baja California, México. It extends 130 km inland, from the Pacific Ocean to the San Matías Pass (near the Gulf of California). Geologic evidence shows that the Agua Blanca Fault has been active during most of the Quaternary. To estimate the seismic hazard that the Agua Blanca Fault represents for the region, it is necessary to recognize its seismic activity. However, seismic data and historical registries of major seismic events associated to this fault are limited. In addition, structural evidence required to calculate the slip rates is scarce. Thus, in order to determine fault movements and hence its seismic risk, it was necessary to use other geological techniques. For that reason, a different multidisciplinary approach to estimate slip rates, magnitude and recurrence times for a geologically active major fault was tested in a selected segment of the Major Agua Blanca Fault (study area: Valle de Agua Blanca, locality: Rancho La Cocina-Rancho Agua Blanca). In this case, correlation of the major alluvial fans displaced by the fault by the use of the clast counting technique and other geological data was used in order to estimate slip rates, magnitude and recurrence times for the Valle de Agua Blanca segment of the fault. By using this method, two major distinctive ancient fans and four small recent fans dissected and offset by the fault within the Valle de Agua Blanca were identified. Fault displacement was established, and the slip rate was calculated to be ∼6 mm/yr consistent with the amount obtained in other studies within the area by the use of other techniques. The average length of each segment of the Agua Blanca Fault is between 20 and 30 km, a surface rupture of 20–30 km accompanies earthquakes of M s 6.7–7.0. This is the case in the Valle Agua Blanca, which is the boundary between two major eastern fault segments 20–35 km long. These lengths, and the slip rate obtained, and using the Bonilla et al., (1984) regression relationship developed for worldwide strike-slip faults, we can estimate the recurrence interval for earthquakes with magnitudes between 6 and 7. The recurrence interval for earthquakes with Ms = 6 to 7 generated by the Agua Blanca Fault in the Valle Agua Blanca is between 75 and 200 yr, with average ground displacements of 0.5–1.25 m. Highlights • Use of a different multidisciplinary approach to estimate slip rates, magnitude and recurrence times for a geologically active major fault was use in a segment (Valle de Agua Blanca) of the Major Agua Blanca Fault when structural evidence for lateral faults required to calculate the slip rates is scarce. • The clast counting technique used in combination with geological data and statistical methods can be use in order to estimate slip rates, magnitude and recurrence times for the Major Agua Blanca Fault. • The slip rate was calculated to be ~6 mm/yr. • Surface rupture of 20 to 30 km accompanies earthquakes of Ms 6.7–7.0. • Recurrence intervals for earthquakes with Ms = 6 to 7 generated by the Agua Blanca fault in the Valle Agua Blanca are between 75 and 200 yr, with average ground displacements of 0.5 to 1.25 m. [ABSTRACT FROM AUTHOR]

Sulfur hexafluoride (SF 6) is a powerful greenhouse gas with a high global warming potential. While SF 6 emissions from urban areas have been extensively studied, our knowledge about SF 6 concentrations in the oceanic atmosphere and its air-sea exchange remains limited. Herein, the concentrations of SF 6 in the atmosphere and surface seawater of the WPO (Western Pacific Ocean) and EIO (Eastern Indian Ocean) were comprehensively characterized from 2019 to 2022 in the first long-term study. The mean mixing ratios of SF 6 over the WPO and EIO during 2019–2020 (2021–2022) were 10.9 (11.2) and 10.9 (11.1) ppt, respectively. The atmospheric SF 6 concentration over the WPO and EIO increased at rates of 0.40 ± 0.06 and 0.58 ± 0.28 ppt yr−1, respectively, surpassing previously reported annual growth rates. The faster growth was primarily attributed to the influence of polluted air masses originating from eastern Asian countries, particularly Japan, Northeast China, and India. This might explain why the radiative forcing caused by SF 6 in the study region was higher than the global average. The concentrations of SF 6 in the surface seawater of the WPO and EIO ranged from 0.33 to 2.54 fmol kg−1, and the distribution was affected by atmospheric concentrations and ocean currents. Estimated air-sea fluxes revealed that the ocean acted as a significant sink of atmospheric SF 6 , and the preliminary estimation suggested oceanic uptake accounts for about 7% of annual global SF 6 emissions. Based on these findings, we tentatively suggest that the strength of the ocean as a sink of SF 6 may warrant reassessment. The global oceanic uptake of SF 6 has the potential to reduce its global abundance and environmental impacts. [Display omitted] • Elevated atmospheric SF 6 levels was due to emission from East Asian countries. • Atmospheric concentration and ocean currents dictated SF 6 in the seawater. • The oceanic uptake of atmospheric SF 6 was about 7% of its emissions. [ABSTRACT FROM AUTHOR]

A new maximum depth record for bony fish (Teleostei) has been set at 8336 m deep in the Izu- Ogasawara Trench (NW Pacific Ocean) represented by video imagery of a snailfish probably Pseupodoliapris belyaevi or a new, endemic species since no physical specimen was captured. Sampling by trap and video was undertaken between 4534 and 9773 m and snailfish (Liparidae) were observed between 6824 and 8336 m, the deepest being a solitary juvenile. In the neighbouring Japan Trench, 31 deployments were made between 4913 and 8022 m and P. belyaevi was observed in 22 of the 24 deployments >6579 m. Two specimens, identified as P. belyaevi, were collected from 8022 m and represent the deepest fish ever caught. In the Japan and Izu-Ogasawara trenches at 6579–7001 m and 6824–7050 m, respectively, two other snailfish species were observed (Liparid sp. indet. 4-JPT and Liparid sp. indet. 4-IOT). A species of snailfish belonging to the putative 'ethereal' morphotype was also observed in the Japan Trench at 7621 and 8022 m (Liparid sp. indet. 3-JPT), but its identification beyond family is still obscure. This study also documents the first hadal fish from the Ryukyu Trench (Liparid sp. indet. 1-RKT) at 7079 and 7339 m. • New maximum depth record for bony fish (Teleostei) has been set. • Snailfish, Pseupodoliapris belyaevi, observed at 8336 m deep in the Izu- Ogasawara. • P. belyaevi, collected from Japan Trench (8022 m) represent the deepest fish ever caught. • Two other snailfish species were observed in Japan and Izu-Ogasawara trenches. • First hadal fish from the Ryukyu Trench (Liparid sp.) observed at 7079 and 7339 m. [ABSTRACT FROM AUTHOR]

Abstract Marine ooids are iconic indicators of shallow seawater carbonate saturation state, and their formation has traditionally been ascribed to physicochemical processes. The Indo-Pacific stands out as a region devoid of oolites, particularly during the Quaternary: the "ooid enigma". Here we present results from recent coring by the International Ocean Discovery Program (IODP Expedition 356) off west Australia that shows that ooid horizons are common in Pleistocene strata up to 730,000 years old. Extensive "ooid factories" were created due to the presence of long-lived tidally influenced flat–topped tropical platforms suitable for intermittent ooid accretion over hundreds to thousands of years during highstands and times of lower sea level. This work suggests marine ooids may actually be more common in Indo-Pacific than previously reported. Past global ocean alkalinity was elevated during Pleistocene glacial periods and continental climate was generally more arid in the Indo-Pacific region compared to interglacials and the Holocene. Therefore, increased aridity associated with higher alkalinity conditions during the glacials facilitated ooid precipitation on adjacent tropical carbonate platforms particularly offshore from arid Australia. This confluence of factors suggests that more "ooid factories" may be encountered by further coring Indo-Pacific regions with Pleistocene flat long-lived carbonate shelves. However, Indo-Pacific Quaternary ooid occurrences outside Australia are rare, suggesting that the Northwest Shelf may be a unique archive of this non-skeletal precipitate. Further investigations into the petrography and geochemistry of pre-Holocene ooid occurrences will provide insights into their origin and the relative role of biotic, physicochemical and other factors in their formation. Highlights • Oolites are rare in the Indo-Pacific, particularly during the Quaternary: the "ooid enigma". • IODP Expedition 356 off west Australia cored common ooid horizons in strata up to 730,000 years old. • Extensive "ooid factories" were deposited on tidally influenced flat–topped tropical platforms. • Oolites were deposited during low and high sea levels in generally arid conditions. • More "ooid factories" may be found by coring regions with flat long-lived carbonate shelves. [ABSTRACT FROM AUTHOR]

Highlights • Variability over Alaska Gyre studied using 14 years of gridded Argo data. • Isopycnal depth and spice anomalies examined. • 1st EOF of isopycnal displacement through upper km linked to PDO. • Eastward (westward) propagation on shallow (deep) isopycnals in Subarctic Current. • Spice anomalies generated through vertical diffusion from 2013/14 marine heatwave. Abstract The deployment of a large number of Argo floats in the northeast Pacific Ocean since 2001 has led to a great increase in the volume of data available to study the regional variability on interannual to decadal time scales. In this paper, gridded fields of hydrographic data from Argo are used to examine the low-frequency variability of representative isopycnal surfaces over the Alaska Gyre in the eastern subpolar North Pacific. Anomalies in the depth of isopycnal surfaces and spice anomalies on these surfaces are considered over the 14 year period, 2004–2017. An EOF analysis is used to characterize the variability occurring at large scales over the region. The leading mode of isopycnal depth anomalies through the upper 1000 m of the water column is found to be related to the Pacific Decadal Oscillation. The response of a stochastic climate model driven by local Ekman pumping is shown to give a reasonable account of variability in the depth of the shallow main pycnocline over the Alaska Gyre, although ocean dynamics must play a role in shaping the spatial response to the wind forcing. Evidence is presented for counter-propagating isopycnal depth anomalies in the Subarctic Current. At the depth of the main pycnocline, propagation is dominated by disturbances that are advected eastward by the mean flow. At greater depths, isopycnal depth anomalies propagate westward at approximately twice the speed of first mode, long baroclinic Rossby waves, consistent with the propagation of Rossby waves seen in altimetric observations of sea surface height variability. The eastward advection of spice anomalies is also evident in the upper ocean. However, the dominant signal in the record is a large-scale positive spice anomaly that forms locally on subsurface isopycnals. Evidence is presented that this anomaly arises mainly from the downward diffusion across the pycnocline of heat associated with the marine heatwave of 2013–14 over the northeast Pacific. The extent to which anomalies are generated locally may limit the potential for decadal prediction of upper ocean conditions over the region. [ABSTRACT FROM AUTHOR]

Abstract Seven subsurface moorings were deployed between 0°N and 7.5°N at 142°E in the western Pacific during August 2014–October 2015, obtaining unprecedented high-quality measurements of the North Equatorial Countercurrent (NECC) between 60 and 200 m and the underlying Northern Subsurface Countercurrent (NSCC) and North Equatorial Subsurface Current (NESC) between 300 and 600 m. During the observation period, the eastward-flowing NSCC showed a mean velocity of 5–15 cm s−1 between 2°N and 4°N, while the NESC manifested as intermittent westward currents of < 5 cm s−1 between 4°N and 6°N. Temporal variabilities in the NSCC and NESC are documented for the first time. Both the NSCC and NESC were strengthened when the NECC shifted to the south in boreal fall. The 2015–2016 El Niño induced significant strengthening of the NECC and weakening of the NESC. Further analysis combining ocean reanalysis data suggests that seasonal variations are likely coherent between the upper and lower (300–600 m) layers and associated with the meridional migration of the NECC. Seasonal variations of the three currents are likely first-mode baroclinic Rossby wave responses to basin-wide wind forcing. By contrast, interannual variations of the NSCC and NESC have more complicated vertical structure. El Niño events generally cause the strengthening and southward migration of the NECC and the weakening of the NESC. Ocean reanalysis products however show difficulties in realistically representing the observed subsurface structure and variability of the three currents, remarking the necessity of enhancing ocean in-situ observation systems. Highlights • Temporal variability in the NSCC and NESC are first documented. • When the NECC shifts to the south, both the NSCC and NESC are strengthened. • Seasonal variations are likely coherent between the upper and lower currents. • The first baroclinic mode responding to wind forcing likely dominates the seasonal variability. • Interannual variations of the NSCC and NESC are more complicated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Deep-sea mud in the Pacific Ocean is enriched in Sc (up to 130 ppm). • 70% of the Sc in the mud can be recovered in 5 min with dilute HCl or H 2 SO 4. • 1 km2 × ∼6 m of the mud can serve 7 times of the global annual Sc consumption. • The mud is a unique material with high resource potentials for both Sc and HREE. Abstract Scandium is a critical element in state-of-the-art, green technologies. However, it is also extremely expensive due to its scarcity. Recently, some deep-sea sediments that contain significant amounts of rare-earth elements that are indispensable to modern industries have been discovered in the western North Pacific Ocean, and the concentration of Sc in these sediments is comparable with that of land-based mines. A simple leaching experiment has demonstrated that up to 70% of Sc in these sediments, contained within biogenic calcium phosphate particles, can be recovered in 5 min, using dilute acids. On the basis of available core samples, we propose that a promising target area to mine Sc is along a west–east transect between longitudes 153°30′ E and 154°00′ E, at an approximate latitude of 21°58′ N. Depending on the depth of the most enriched sediment layer, just 1 km2 of the sediment could potentially yield 3.3–6.6 times the current global annual consumption of Sc. Because these sediments contain an unusually high concentration, at commercial quantities, of industrially important, heavy rare-earth elements, apart from Sc, they could be a productive source for the long-term extraction of these critical metals. [ABSTRACT FROM AUTHOR]

In this study, the trophic structure of the pelagic copepod community was analyzed in six geographical zones in the eastern tropical Pacific Ocean. Zooplankton samples were collected on two oceanographic cruises from August to December 2003 using a bongo cone net (333 μm mesh light). The isotopic signatures were measured as δ 15 N and δ 13 C in twelve selected species based on their dominance and their feeding types. We observed a significant latitudinal gradient in δ 15 N values, generally increasing northwards. The values of δ 13 C isotopes did not show a significant longitudinal gradient, but geographical differences occurred in some species. Pleuromamma robusta was recognized as the species with the highest trophic position in the copepod community. In general, there was a positive relationship between average body size and trophic position, except for the herbivorous species Eucalanus inermis , which was detected in the lowest trophic position. The isotopic niche was similar for each of the 12 species of copepods studied, but in most cases, the niche overlap between each pair of species was low and not higher than 50%. While the differences in isotopic signatures can be attributed mainly to the dominant nutrient sources in each zone, the low trophic niche overlap may be explained by the differential spatial distribution of species, reducing competition for food resources. [ABSTRACT FROM AUTHOR]

Abstract We performed X-ray adsorption fine structure (XAFS) analyses of Y, Ce, Fe, and P for rare earth elements and yttrium-rich muds (REY-rich muds) from the two regions of the Pacific Ocean: the eastern South Pacific and the central North Pacific. Yttrium K-edge XAFS revealed that calcium phosphate (apatite) is the common host of REY even in the hydrothermal sediments near the East Pacific Rise (EPR), as it is in REY-rich muds in the other regions including the western North Pacific and the Indian Ocean. In contrast, Ce L 3 -edge XANES revealed a systematic difference in the major oxidation states of Ce between the central North Pacific, where Ce(III) is dominant (60–77%), and the eastern South Pacific, where Ce(IV) is dominant (55–83%). The dominance of Ce(IV) indicates a strong hydrothermal influence on REY behavior in the eastern South Pacific. Based on inter-elemental relationships, it has long been considered that hydrothermal Fe precipitates control the REY concentration in the sediments of the eastern South Pacific. However, on the basis of these spectroscopic findings, we propose that the initial uptake of REY by rapid precipitation of hydrothermal Fe-Mn (oxyhydr)oxides is followed by eventual fixation of REY to apatite via REY redistribution in the oxic sediments. In contrast, REY accumulation in the central North Pacific can be explained by primary seawater-mineral interactions with apatite and small contributions of Mn oxides. Phosphorous and Fe K-edge XANES for the eastern South Pacific sediments both show transitions in their major species with distance from the EPR, from P adsorbed on goethite to apatite and goethite to montmorillonite, respectively. In particular, apatite appears coincident with the occurrence of the REY-rich muds, even though the Fe species still suggests intensive deposition of hydrothermal goethite. The correlation between the mass accumulation rates (MAR) of Fe and P together with these results implies the existence of two types of the apatite: biogenic apatite (i.e., fish debris) and authigenic one derived from P species adsorbed on hydrothermal Fe-Mn (oxyhydr)oxides. This result implies that authigenic apatite forms uniquely in the geological setting around the EPR, and also that biogenic apatite is responsible for the widespread formation of the REY-rich muds. We found that apatite is of specific importance as the eventual host of REY within the REY-rich muds, but various geochemical processes account for the origin of apatite and its accumulation of REY. [ABSTRACT FROM AUTHOR]

Abstract Environmental history studies have focused on the negative environmental and equal rights access to natural resources, more recently scholars becoming interested in the study of successful cases of natural resources management. We present a successful co-management fisheries case that is product of a century of environmental history in the Mexican North Pacific region. In this historical process, the passage from rancher settlers to well-organized fishermen in fishing cooperatives took place together with the transition from an intensive exploitation to a sustainable co-management system. External factors played a crucial role in regional fisheries development, first by triggering their being with the arrival of a Japanese company and, afterwards by changing its course during the Great Depression. Two current threats have emerged from unpredictable and detrimental marine environmental factors related to global warming, and from cultural roots loss due, once more, to external factors. We conclude that, at present, the nature of the next historical stage of this enlightened environmental history self-learning case remains unknown. Highlights • A successful co-management fisheries case was the product of a century of environmental history. • Rancher settlers changed to well-organized fishermen in fishing cooperatives. • An intensive system of exploitation transited to one of sustainable co-management resources. • Crucial role of two external factors in region's development: triggering and giving a new course. • Unknown nature of the next historical stage due to recent climatic and cultural threats. [ABSTRACT FROM AUTHOR]

Abstract The atmospheric deposition of water-soluble organic carbon (WSOC) contributes to the open ocean dissolved organic carbon (DOC) reservoir similarly to riverine discharge. However, information on the sources and composition of water-soluble organic matter (WSOM) in marine aerosols remains scarce, particularly at the molecular level. By using ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), we identified approximately ten thousand molecular formulas in marine aerosols collected over the China coastal seas and the northwestern Pacific Ocean (NWPO). Even though their molecular compositions were highly variable (Bray-Curtis distance: 0.12–0.74), four distinctive origins, namely, marine biogenic sources, secondary organic aerosols (including CHO, CHON formulas derived from biogenic volatile organic compounds (VOCs) and organosulfate derived from both biogenic and anthropogenic VOCs), soil-derived organic matter (OM) and biomass and fossil fuel burning-derived polycyclic aromatics (including highly condensed organosulfur compounds) and unsaturated compounds, were discovered. Moreover, the different types of aerosols, including aerosols from the NWPO (marine-influenced), NWPO (dust) and China coastal seas, contained various proportions of organics from different sources. The NWPO (marine-influenced) aerosols were enriched with sea spray-derived OM, which was widely distributed and was likely related to marine biological activity. The NWPO (dust) aerosols exhibited a higher fraction of soil-derived OM, while the China coastal sea aerosols exhibited a much higher fraction of organosulfate than the other aerosols. Our investigation provided detailed molecular compositional and source information for marine aerosols over the northwestern Pacific Ocean, which can be utilized to understand the composition of WSOM deposited on the sea surface. Highlights • Approximately ten thousand of molecular formulas were identified in marine aerosols. • Anthropogenic organic matter can be transported to the open ocean. • Sea spray compounds were widely observed but were enriched in the open ocean aerosols. • China coastal seas aerosols contained higher fraction of organosulfate compounds. • Dust aerosols exhibited a higher fraction of soil-derived organic matter. [ABSTRACT FROM AUTHOR]

Abstract Anaerobic ammonium-oxidizing (anammox) bacteria produce dinitrogen gas from nitrite and ammonium under anoxic conditions and significantly contribute nitrogen removal processes in marine environments. Distribution and activity of anammox bacteria in a marine water column have been well studied in some oxygen deficient waters such as Black Sea, Arabian Sea, Namibian upwelling and Peruvian upwelling systems. However, the habitable area of anammox bacteria in the Pacific Ocean is still an open question. Here, we report distribution, abundance and phylogeny of anammox bacteria in the water column along the north-south transect (40⁰S to 55⁰N, 170⁰W) of the Pacific Ocean in order to determine their habitable area in the open ocean. Anammox bacteria-specific 16S rRNA gene was detected at 10 locations mostly from oxygen minimum depths (OMD) where dissolved oxygen (DO) concentration ranged from 10.9 to 46.2 µmol Kg-1. Their abundance measured by qPCR ranged from 3.69 ± 1.35 × 102 copies L-1 to 474 ± 15 × 102 copies L-1. The phylogenetic analysis showed that anammox bacteria detected in this study were all related to Candidatus Scalindua species and clustered into three subgroups: the Scalindua brodae/sorokinii cluster, the sediment cluster and the Arabian Sea cluster. Relationship between the abundance of anammox bacteria and DO concentration varied among these 3 clusters, suggesting their difference in oxygen sensitivity. Although rate measurement of anammox reaction using 15N-labeled substrates failed for all OMD samples tested during the cruise, this study unveiled the distribution of anammox bacteria in the open ocean oxygen minimum zone (OMZ) where oxygen deficiency is not extreme but moderate, which provides an insight into the potential distribution of anammox bacteria in marine environments. [ABSTRACT FROM AUTHOR]

Abstract In this study, we carried out grain size and heavy metal analyses and also assessed heavy metal enrichment and ecological risk indices in ten sediment samples collected by the manned submersible Jiaolong at different segments of the Yap Trench. The results showed that the sediments in the Yap Trench were mainly slumping deposits composed of sandy silt. Heavy metals in the sediments showed different spatial distribution patterns from north to south direction of the trench. The distribution pattern of these heavy metals also differed in the eastern and western flanks of the trench. From the results of the enrichment factors, only arsenic, chromium, and manganese showed a slight enrichment. However, all elements were affected by natural factors. Further, most elements showed a low ecological risk, and only arsenic showed a moderate risk at two stations. Finally, the potential ecological risk of the whole study area was at a low level. Highlights • The sediments in the Yap Trench are mainly slumping deposits composing of sandy silt. • The concentration of heavy matals has increased in the past 30,000 years, but still maintain natural source characteristics. • The potential ecological risk index results also indicate a low ecological risk of the heavy metals. • The arsenic elelment in some stations shows moderate ecological risk. [ABSTRACT FROM AUTHOR]

Abstract World Heritage status for selected sites in Areas Beyond National Jurisdiction is under active consideration, and the Costa Rica Thermal Dome in the eastern tropical Pacific Ocean is a feasible candidate site. A scientific expedition to the area in April 2017 added to biological baseline data but also confirmed presence of microplastics in the water column. National and regional efforts are being made by Central American countries to strengthen mechanisms for integrated ocean management, educate coastal communities and give early consideration to potential future threats such as ocean fertilisation. This paper concludes that to achieve World Heritage status for this iconic site requires an entity to both propose the area and report on its status. Bringing into force the Antigua Convention, a Regional Seas Convention for the Eastern Tropical Pacific, would provide an appropriate platform for Central American governments to enact protective measures. Highlights • New evidence reaffirms the Costa Rica Thermal Dome as meeting the EBSA criteria. • Outstanding Universal Value spurs interest in Dome as candidate World Heritage site. • Microplastics are found in the water column, far from obvious point sources. • Diverse management and clear governance plans are required for key sites in ABNJ. • Ratification of a Regional Seas Convention is advocated as an essential first step. [ABSTRACT FROM AUTHOR]

Oceanic and atmospheric modes play a key role in modulating climate variations, particularly on interannual and interdecadal scales, causing an indirect response of regional climate to external forcings. This study comprehensively investigated the time-varying linkages among dominant oceanic and atmospheric modes of the Pacific and Atlantic areas on different timescales using the scale space multiresolution correlation analysis. For the Pacific Ocean, the Interdecadal Pacific Oscillation (IPO) shows closer matches with the El Niño-Southern Oscillation (ENSO) than with the Pacific Decadal Oscillation (PDO). This indicates that the ENSO dominates climate variability of the whole Pacific Ocean not only on interannual but also on interdecadal scales. Interdecadal variations of the IPO appear to be more closely linked to southern Pacific Ocean climate before ∼1940, but become more closely linked to northern Pacific Ocean after ∼1940. The shifts on interdecadal connections among northern, tropical and southern parts of the Pacific Oceans seems to be related to the phase shifts of the IPO/PDO, which may contribute to the cooling trend from 1940s to 1970s. For the Atlantic Ocean, the Atlantic Multi-decadal Oscillation (AMO) is closely linked to the North Atlantic Oscillation (NAO) on the interdecadal scale before ∼1940. [ABSTRACT FROM AUTHOR]