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BackgroundConsiderable resources are spent to track fish movement in marine environments, often with the intent of estimating behavior, distribution, and abundance. Resulting data from these monitoring efforts, including tagging studies and genetic sampling, often can be siloed. For Pacific salmon in the Northeast Pacific Ocean, predominant data sources for fish monitoring are coded wire tags (CWTs) and genetic stock identification (GSI). Despite their complementary strengths and weaknesses in coverage and information content, the two data streams rarely have been integrated to inform Pacific salmon biology and management. Joint, or integrated, models can combine and contextualize multiple data sources in a single statistical framework to produce more robust estimates of fish populations.MethodsWe introduce and fit a comprehensive joint model that integrates data from CWT recoveries and GSI sampling to inform the marine life history of Chinook salmon stocks at spatial and temporal scales relevant to ongoing fisheries management efforts. In a departure from similar models based primarily on CWT recoveries, modeled stocks in the new framework encompass both hatchery- and natural-origin fish. We specifically model the spatial distribution and marine abundance of four distinct stocks with spawning locations in California and southern Oregon, one of which is listed under the U.S. Endangered Species Act.ResultsUsing the joint model, we generated the most comprehensive estimates of marine distribution to date for all modeled Chinook salmon stocks, including historically data poor and low abundance stocks. Estimated marine distributions from the joint model were broadly similar to estimates from a simpler, CWT-only model but did suggest some differences in distribution in select seasons. Model output also included novel stock-, year-, and season-specific estimates of marine abundance. We observed and partially addressed several challenges in model convergence with the use of supplemental data sources and model constraints; similar difficulties are not unexpected with integrated modeling. We identify several options for improved data collection that could address issues in convergence and increase confidence in model estimates of abundance. We expect these model advances and results provide management-relevant biological insights, with the potential to inform future mixed-stock fisheries management efforts, as well as a foundation for more expansive and comprehensive analyses to follow.

Predation pressure and herbivory exert cascading effects on coral reef health and stability. However, the extent of these cascading effects can vary considerably across space and time. This variability is likely a result of the complex interactions between coral reefs' biotic and abiotic dimensions. A major biological component that has been poorly integrated into the reefs' trophic studies is the microbial community, despite its role in coral death and bleaching susceptibility. Viruses that infect bacteria can control microbial densities and may positively affect coral health by controlling microbialization. We hypothesize that viral predation of bacteria has analogous effects to the top-down pressure of macroorganisms on the trophic structure and reef health. Here, we investigated the relationships between live coral cover and viruses, bacteria, benthic algae, fish biomass, and water chemistry in 110 reefs spanning inhabited and uninhabited islands and atolls across the Pacific Ocean. Statistical learning showed that the abundance of turf algae, viruses, and bacteria, in that order, were the variables best predicting the variance in coral cover. While fish biomass was not a strong predictor of coral cover, the relationship between fish and corals became apparent when analyzed in the context of viral predation: high coral cover (> 50%) occurred on reefs with a combination of high predator fish biomass (sum of sharks and piscivores > 200 g m-2) and high virus-to-bacteria ratios (> 10), an indicator of viral predation pressure. However, these relationships were non-linear, with reefs at the higher and lower ends of the coral cover continuum displaying a narrow combination of abiotic and biotic variables, while reefs at intermediate coral cover showed a wider range of parameter combinations. The results presented here support the hypothesis that viral predation of bacteria is associated with high coral cover and, thus, coral health and stability. We propose that combined predation pressures from fishes and viruses control energy fluxes, inhibiting the detrimental accumulation of ecosystem energy in the microbial food web.

Purse‐seine fishers using drifting fish aggregating devices (dFADs), mainly built with bamboo, plastic buoys, and plastic netting, to aggregate and catch tropical tuna, deploy 46,000–65,000 dFADs per year in the Pacific Ocean. Some of the major concerns associated with this widespread fishing device are potential entanglement of sea turtles and other marine fauna in dFAD netting; marine debris and pollution; and potential ecological damage via stranding on coral reefs, beaches, and other essential habitats for marine fauna. To assess and quantify the potential connectivity (number of dFADs deployed in an area and arriving in another area) between dFAD deployment areas and important oceanic or coastal habitat of critically endangered leatherback (Dermochelys coriacea) and hawksbill (Eretmochelys imbricata) sea turtles in the Pacific Ocean, we conducted passive‐drift Lagrangian experiments with simulated dFAD drift profiles and compared them with known important sea turtle areas. Up to 60% of dFADs from equatorial areas were arriving in essential sea turtle habitats. Connectivity was less when only areas where dFADs are currently deployed were used. Our simulations identified potential regions of dFAD interactions with migration and feeding habitats of the east Pacific leatherback turtle in the tropical southeastern Pacific Ocean; coastal habitats of leatherback and hawksbill in the western Pacific (e.g., archipelagic zones of Indonesia, Papua New Guinea, and Solomon Islands); and foraging habitat of leatherback in a large equatorial area south of Hawaii. Additional research is needed to estimate entanglements of sea turtles with dFADs at sea and to quantify the likely changes in connectivity and distribution of dFADs under new management measures, such as use of alternative nonentangling dFAD designs that biodegrade, or changes in deployment strategies, such as shifting locations. [ABSTRACT FROM AUTHOR]

El Niño Southern Oscillation, a global climate phenomenon, occurs in the tropical Pacific with an anomalous warming phase (El Niño) and a cooling phase (La Niña) spanning for 2–5 years. A substantial decline of Niño3.4 region's spring bloom chlorophyll-a concentration (Chl-a) is an intrinsic characteristic of the central Pacific during the El Niño onset period, which has been considered as a predictor of the El Niño by earlier studies. This study investigated the concept, a marked decline of spring bloom Chl-a as the predictor of the El Niño, using satellite-measured Chl-a from MODIS Aqua for the period 2003–2023 in relation to the Oceanic Niño Index (ONI) and subsurface properties. It revealed that Chl-a exhibits a significant inverse relationship with ONI during past El Niño events. An intense, continuous decreasing phase of Chl-a during the spring season (February–April) of 2023 may indicate the onset of El Niño. The decline of the spring bloom Chl-a concentration has been explained as the response to the weakening of the upwelling strength in the study domain and associated nutrient depletion in the euphotic zone. [ABSTRACT FROM AUTHOR]

Asian dust delivers highly reactive iron (FeHR) to the Pacific Ocean, affecting marine biogeochemical cycles and Earth's climate. Tracing the source of dust deposited in the Pacific is vital for assessing global nutrient cycles but poses challenges. This work applies the (234U/238U) activity ratio to determine the pre‐deposition time and provenance of dust in North Pacific Ocean sediments (Ocean Drilling Program site 1209B). Results indicate a consistent dust pre‐deposition time (134 ± 10 ka) over the past 300,000 years, except during Marine Isotope Stage 7 when volcanic ash input shortened it to 31 ± 19 ka. Comparing the dust pre‐deposition times to those of the potential source deserts, we identify the dust transported to the North Pacific Ocean was primarily from the Taklamakan Desert, which contains higher FeHR content than other deserts. This finding enhances our understanding of soluble Fe supplied to the oceans, especially in dust circulation models. Plain Language Summary: Unraveling the provenance of aeolian dust deposited in the oceans is critical for understanding marine biogeochemical cycles, past climate changes, and dust transport mechanisms. Here we measured the (234U/238U) activity ratio of marine sediments in the North Pacific Ocean to understand the source and pre‐deposition time of dust deposited in the Pacific. The source of dust in the Pacific has remained debated because of the non‐unique geochemical signatures of possible source regions and the complexity introduced by the volcanic ash. The (234U/238U) of the dust fraction in marine sediments informs the source‐to‐sink transport time for dust particles, providing a new source tracer. We compared the (234U/238U)‐derived pre‐deposition time, Nd isotopes, grain size, magnetic susceptibility and aeolian dust flux of the North Pacific marine sediments to those of potential dust source regions, and identify the Taklamakan Desert as a major source delivering dust to the North Pacific. Our work highlights the (234U/238U) and associated particle pre‐deposition time as a promising tool for tracing sources of dust in marine sediments, holding profound implications for our understanding of global dust‐nutrient cycles. Key Points: Uranium isotope‐based pre‐deposition time serves as a novel tool to trace the provenance of Asian dust transported to the North Pacific OceanDust pre‐deposition time at site 1209B remains relativity stable (134 ± 10 ka), but decreases during MIS 7 due to volcanic ash inputTaklimakan Desert is the major source of dust delivered to the North Pacific Ocean, supplying dust with highly reactive iron [ABSTRACT FROM AUTHOR]

The Hunga Tonga–Hunga Ha'apai volcanic eruption on January 15, 2022 generated a tsunami that affected the entire Pacific Ocean. Tsunami waves from the event have been generated both by incoming waves from the source area with a long-wave speed in the ocean of ~200–220 m/s, and by an atmospheric wave propagating at a sound speed of ~315 m/s. Such a dual source mechanism created a serious problem and was a real challenge for the Pacific tsunami warning services. The work of the Russian Tsunami Warning Service (Yuzhno-Sakhalinsk) during this event is considered in detail. The tsunami was clearly recorded on the coasts of the Northwest Pacific and in the adjacent marginal seas, including the Sea of Japan, the Sea of Okhotsk, and the Bering Sea. We examined high-resolution records (1-min sampling) of 20 tide gauges and 8 air pressure stations in this region for the period of January 14–17, 2022. On the Russian coast, the highest waves, with a trough-to-crest wave height of 1.3 m, were recorded at Malokurilskoe (Shikotan Island) and Vodopadnaya (southeastern coast of Kamchatka). Using numerical simulation and data analysis methods, we were able to separate oceanic "gravity" tsunami waves from propagating atmospheric pressure waves. In general, we found that on the outer (oceanic) coasts and southern coast of the Sea of Okhotsk, oceanic tsunami waves prevailed, while on the coast of the Sea of Japan, oceanic and atmospheric tsunami waves had similar heights. [ABSTRACT FROM AUTHOR]

Rates at which a community recovers after disturbance, or its resilience, can be accelerated by increased net primary productivity and recolonization dynamics such as recruitment. These mechanisms can vary across biogeographic gradients, such as latitude, suggesting that biogeography is likely important to predicting resilience. To test whether community resilience, informed by functional and compositional recovery, hinges on geographic location, we employed a standardized replicated experiment on marine invertebrate communities across four regions from the tropics to the subarctic zone. Communities assembled naturally on standardized substrate while experiencing distinct levels of biomass removal (no removal, low disturbance, and high disturbance), which opened space for new colonizers, thereby providing a pulse of limited resource to these communities. We then quantified functional (space occupancy and biomass) and compositional recovery from these repeated pulse disturbances across two community assembly timescales (early and late at 3 and 12 months, respectively). We documented latitudinal variation in resilience across 47° latitude, where speed of functional recovery was higher toward lower latitudes yet incomplete at late assembly in the tropics and subtropics. The degree of functional recovery did not coincide with compositional recovery, and regional differences in recruitment and growth likely contributed to functional recovery in these communities. While biogeographic variation in community resilience has been predicted, our results are among the first to examine functional and compositional recovery from disturbance in a single large‐scale standardized experiment. [ABSTRACT FROM AUTHOR]

The North Pacific meridional mode (NPMM) peaking in boreal spring influences El Niño–Southern Oscillation (ENSO) properties in the ensuing winter. Whether the precursory impact of NPMM on the spatial diversity of ENSO has decadal variation remains unknown. Using long-term reanalysis datasets, we find that the interdecadal Pacific oscillation (IPO) significantly modulates the NPMM forcing on two types of ENSO. During the positive IPO (+IPO) phase, a strengthened background Aleutian low and southward-shifted storm track, in comparison to the negative IPO (−IPO) phase, produce stronger basin-scale negative geopotential height tendency anomalies over the North Pacific through synoptic-scale eddy–mean flow interaction. Such strong background negative tendency facilitates an Aleutian low–like pressure monopole rather than a North Pacific Oscillation (NPO)-like pressure dipole in boreal spring, leading to a weak NPMM that cannot effectively promote development of either a central Pacific (CP) or an eastern Pacific (EP) ENSO. By contrast, the NPO-like dipole enhances in boreal spring during −IPO, corresponding to stronger and more frequently occurring NPMM events that induce a robust CP-ENSO-like response in boreal winter. Moreover, the −IPO-related tropical Pacific mean states and the associated positive feedbacks cause a strong decrease in mixed layer temperature variance in the equatorial eastern Pacific, but a slight increase in the central Pacific, thus further contributing to the enhanced correlation between NPMM and CP-ENSO. Therefore, −IPO has played a role in the stronger impact of NPMM on CP-ENSO since the 1990s, and the modulation effects of IPO should be considered in understanding the extratropical–tropical climatic connection and ENSO spatial diversity. [ABSTRACT FROM AUTHOR]

Eulimidae is a highly diverse family of gastropods that are often parasites of echinoderms. They are cosmopolitan and live from the intertidal to great depths. Despite its wide geographic and bathymetric distribution, no species of Eulimidae have been reported for the Salas & Gómez Ridge to date. In this study, we describe Melanella martarum sp. nov., which was collected during the EPIC oceanographic cruise onboard RV Mirai (JAMSTEC, Japan) in 2019. Seven specimens were collected with a modified Agassiz trawl on the summit of seamount "Pearl'' (Zhemchuznaya) in the Salas & Gómez Ridge (25.59°S, 89.13_W) at 545 m depth. The morphology of M. martarum sp. nov. was compared with other Melanella species reported for the area, including Chile and Rapa Nui. DNA was extracted and partial sequences of the mitochondrial genes Cytochrome Oxidase 1 (COI) and 16S rDNA, and the nuclear gene Histone 3 (H3) were sequenced. Melanella martarum sp. nov. has morphological characteristics that separate it from other species of Melanella, such as the thickness and color of the shell, and the shape of the protoconch. In addition, M. martarum sp. nov. was genetically differentiated from other Melanella spp. sequences (uncorrected p distances from 18,1_8.6% in mitochondrial COI and 16S rDNA to 3% in nuclear H3 sequences). Although there is not much molecular data available for Eulimidae, the phylogenetic analysis confirms the results obtained by morphology, placing the species found on the Salas & Gómez Ridge within the genus Melanella. The current study advances the understanding of the poorly known benthic fauna found on seamounts in the easternmost part of the Sala & Gómez ridge, a location distinguished by a high level of endemism. [ABSTRACT FROM AUTHOR]

Ommastrephid squids are migratory and economically important species in the Pacific Ocean. Pelagic squids have a short lifespan and are highly affected by climate change. Understanding the ontogenetic dispersal of squids under environmental fluctuations can ensure proper and scientific management of these species. Samples of neon flying squid (Ommastrephes bartramii) and jumbo flying squid (Dosidicus gigas) were collected in the Northwest Pacific and Southeast Atlantic (offshore waters of Peru) oceans, respectively, in different years. Then, five trace elements of the grounded statoliths were measured and quantified using laser ablation inductively coupled plasma‒mass spectrometry (LA-ICP‒MS) to determine their ontogenetic and inter-annual variations. Furthermore, the ontogenetic dispersals of the two squid species in different years were reconstructed. The results showed that for O. bartramii, the inter-annual differences in the Sr/Ca, Ba/Ca, and Na/Ca ratios were significant (P < 0.05). However, no significant inter-annual difference was observed in the Mg/Ca ratio (P > 0.05). For D. gigas, the inter-annual differences in the Sr/Ca, Mg/Ca, and Na/Ca ratios were significant (P < 0.05). However, no significant inter-annual difference was observed in the Ba/Ca ratio (P > 0.05). Sea surface temperature (SST) indicators were selected, including the Mg/Ca ratio for O. bartramii and Sr/Ca, Ba/Ca, and Na/Ca ratios for D. gigas, and regression models were estimated. Based on a Bayesian model, the high probability of occurrence of these indicators in a particular area represented the possible optimal location of squids, and the potential ontogenetic dispersals of the two squid species in different years were reconstructed. We found that the ontogenetic dispersals of the squids differed in different years. However, they migrated in the same direction. Nevertheless, El Niño–Southern Oscillation (ENSO) events affected the habitat position of squids and the size of their habitat area at each stage. [ABSTRACT FROM AUTHOR]

Continuous Plinian eruptions often excite atmospheric modes of ∼3.7 and ∼4.4 mHz, which are observed as harmonic oscillations of ionospheric total electron content (TEC) by global navigation satellite system (GNSS) receivers. Such TEC oscillations started shortly after the great eruption of the Hunga Tonga–Hunga Ha'apai (HTHH) submarine volcano at ∼4:14 UT, on 2022 January 15. Here I analyse GNSS data at stations within ∼4000 km from the volcano to study temporal and spatial distribution of such atmospheric modes. Strong ∼3.7 mHz TEC oscillations in near fields started shortly after the eruption onset and propagated outward with the sound speed from HTHH. Later such TEC oscillations became strong again with the amplitude peak at the distance ∼1400 km from HTHH. Such far field oscillations occurred also above New Zealand and the Solomon Islands, ∼3000 km from HTHH. Their amplitudes seem correlated with those of the 0S29 solid earth mode, suggesting that vertical surface vibrations underneath may play a role in maintaining the atmospheric mode. Onset of the far field TEC oscillations are synchronized with the local sunrise, possibly controlled by diurnal changes in the ionospheric electron density. [ABSTRACT FROM AUTHOR]

Sea surface temperature (SST) variability in the East China Sea–Kuroshio (EK) region has important implications for the surrounding weather, climate, and marine ecology. The year-to-year variations of the EK SST are expectedly linked to El Niño–Southern Oscillation (ENSO), the predominant predictability source of seasonal-to-interannual climate variability. Surprisingly, no significant SST signal is observed in the EK region when focusing on the ENSO autumn–winter season with the persistent and pronounced SST anomalies in the tropical Pacific. We find that a remarkable seasonal reversal appears in the ENSO–EK SST connection, shifting from a negative relationship in autumn [Aug(0)–Oct(0)] to a positive relationship in winter [Dec(0)–Feb(1)]. This reversal is mainly attributed to the seasonally varying ENSO-associated western North Pacific (WNP) atmospheric circulation patterns. During ENSO autumns, the anomalous WNP anticyclone is confined south of 20°N, which is accompanied with cyclonic circulation anomalies in the EK region. The associated anomalous northerly wind tends to enhance the background northerly wind, thereby facilitating the local SST cooling mainly via the wind–evaporation–SST effect. In the subsequent winter, the ENSO-related WNP anticyclonic anomalies intensify and extend toward the EK region. Consequently, the weakened background northerly wind induced by southerly wind anomalies leads to the increase of downward latent and sensible heat flux in the EK region, fostering the local SST warming. The observed seasonal reversal of ENSO impacts can be evidenced by the tropical Pacific pacemaker experiments, emphasizing the importance of seasonally modulated ENSO teleconnection and holding implications for the local SST climate prediction. [ABSTRACT FROM AUTHOR]

The relative roles of the oceanic and atmospheric processes in the pattern formation of the equatorial Pacific sea surface temperature (SST) response to global warming is investigated using a set of climate model experiments embedded with a novel partial coupling technique. The modeling results show that the SST response experiences a transition from a La Niña-like warming pattern at the initial stage to an El Niño-like warming pattern at the quasi-equilibrium stage. By decomposing anomalous equatorial Pacific SST into atmosphere thermally forced passive component and ocean dynamically induced active component, it is found that the SST warming pattern at both stages is entirely induced by its active component. Specifically, the meridional and vertical ocean circulation changes play a dominant role in forming the La Niña-like SST warming pattern at the initial stage, and the zonal and meridional ocean circulation changes are responsible for the formation of the El Niño-like SST warming pattern at the quasi-equilibrium stage. In contrast, the passive SST at both stages is characterized by a zonally uniform warming along the equator, which can be explained by a balance between the total effect of the heat transport divergence associated with the mean ocean circulation and the effect of the passive surface heat flux change. In addition, this study finds that it is the slowdown of the Pacific subtropical cells during the transition period that controls the evolution of the equatorial SST warming pattern by changing the meridional and vertical ocean heat transports. [ABSTRACT FROM AUTHOR]

The half‐life of 228Ra (5.7 years) aligns well with near‐surface and near‐bottom ocean mixing timescales. Because 228Ra is sourced from sediments, regions of enhanced activity represent water that has recently interacted with sediments on the continental margin or seabed. The GP15 meridional transect from Alaska to Tahiti along152°W encountered several regions in the upper ocean where 228Ra was enriched. These enrichments follow surface and subsurface ocean current patterns and pair with earlier measurements of 228Ra and transient radionuclides to reveal the origins of these enriched regions. An enriched region at Alaska margin stations 1–3 was sourced locally but did not extend to the Alaskan trench at station 4. A large shallow region between 47° and 32°N. was sourced from the west by the North Pacific Current; another shallow enriched region between 11° and 5° N was also sourced from the west by the North Equatorial Countercurrent. Subsurface enrichments (100–400 m) between 18 and 47°N were associated with Central Mode Water and North Pacific Intermediate Water. The 228Ra activities in the upper Pacific were six times lower than activities in the Atlantic. In deep waters the primary enrichment was 27°–47°N. Two stations (32° and 37°N) were especially enriched, having near‐bottom inventories several times greater than other stations. With these two exceptions the remaining Pacific stations exhibited averaged inventories lower than those in the Atlantic. There was one region of enriched 223Ra (half‐life = 11 days) above the Puna Ridge near Hawaii. Plain Language Summary: The international GEOTRACES program aims to identify processes and quantify fluxes that control the distribution of trace elements and isotopes (TEIs) in the ocean. Some TEIs are important micronutrients, which may control biological productivity. Others may become concentrated as they pass up the food web and reach potentially harmful levels in some seafood. But measurements of these TEIs are not adequate to determine controlling processes or quantify their fluxes in the marine environment. Radionuclide tracers provide a means to link TEI measurements with fluxes and processes. Here we employ measurements of 228Radium (half‐life = 5.75 years) to trace water movements and current speeds in the upper Pacific and to determine regions near the seabed where sediment‐water interactions are most intense. The upper ocean measurements confirmed a broad circulation pattern that brought water from the Asian margin to the northeast Pacific at speeds of 2–8 cm/sec, in agreement with other estimates of these current speeds. Near the seabed we discovered a region of enhanced 228Ra activity indicating intense sediment‐water interactions. Such regions may control the release of TEIs from the seabed to the water column. We anticipate others will utilize these data to elucidate aspects of other TEI distributions. Key Points: Several open‐ocean regions of enriched 228Ra were documented in the North and Equatorial Pacific at 152°WThe upper ocean 228Ra‐enriched regions correspond to major surface and subsurface currents transporting water from the Asian marginOne seabed region near 32°N was especially enriched in 228Ra [ABSTRACT FROM AUTHOR]

This study evaluated the movement patterns of four Pacific sleeper sharks (Somniosus pacificus) outfitted with satellite-based tags off the California coast, a region for which there is no reported tracking data. Pacific sleeper sharks (1.5–2.1 m) attained maximum individual depths ranging from 603–1,323 m, with an overall average depth of 424 ± 84 m. Depth distribution was relatively similar between day and night, remaining well below the thermocline throughout periods at liberty. A 180-cm individual tagged off central California exhibited a deeper but more consistent depth distribution throughout the day (µ = 528 ± 28 m) and night (µ = 545 ± 26 m), whereas a 221-cm shark tagged off southern California occurred deeper during the day (µ = 392 ± 43 m) than at night (µ = 352 ± 62 m) with continuous vertical oscillations between 300 and 500 m. Ambient water temperatures at depth ranged from 3.3–11.0°C, with a collective average temperature of 7.3°C. Despite extensive and continuous vertical movements, horizontal displacement was minimal over the 30-d tracks (µ = 1.7 km/d). Although the data presented here are temporally and spatially limited, findings support previous reports of consistent vertical oscillations within other regions in the Pacific. Insights into the movements and habitat use of this vulnerable elasmobranch provides a better understanding of the species within a previously undocumented portion of its range.

Biological nitrogen fixation is a major important source of nitrogen for low-nutrient surface oceanic waters. Nitrogen-fixing (diazotrophic) cyanobacteria are believed to be the primary contributors to this process, but the contribution of non-cyanobacterial diazotrophic organisms in oxygenated surface water, while hypothesized to be important, has yet to be demonstrated. In this study, we used simultaneous 15N-dinitrogen and 13C-bicarbonate incubations combined with nanoscale secondary ion mass spectrometry analysis to screen tens of thousands of mostly particle-associated, cell-like regions of interest collected from the North Pacific Subtropical Gyre. These dual isotope incubations allow us to distinguish between non-cyanobacterial and cyanobacterial nitrogen-fixing microorganisms and to measure putative cell-specific nitrogen fixation rates. With this approach, we detect nitrogen fixation by putative non-cyanobacterial diazotrophs in the oxygenated surface ocean, which are associated with organic-rich particles (

Enzymes catalyze key reactions within Earths life-sustaining biogeochemical cycles. Here, we use metaproteomics to examine the enzymatic capabilities of the microbial community (0.2 to 3 µm) along a 5,000-km-long, 1-km-deep transect in the central Pacific Ocean. Eighty-five percent of total protein abundance was of bacterial origin, with Archaea contributing 1.6%. Over 2,000 functional KEGG Ontology (KO) groups were identified, yet only 25 KO groups contributed over half of the protein abundance, simultaneously indicating abundant key functions and a long tail of diverse functions. Vertical attenuation of individual proteins displayed stratification of nutrient transport, carbon utilization, and environmental stress. The microbial community also varied along horizontal scales, shaped by environmental features specific to the oligotrophic North Pacific Subtropical Gyre, the oxygen-depleted Eastern Tropical North Pacific, and nutrient-rich equatorial upwelling. Some of the most abundant proteins were associated with nitrification and C1 metabolisms, with observed interactions between these pathways. The oxidoreductases nitrite oxidoreductase (NxrAB), nitrite reductase (NirK), ammonia monooxygenase (AmoABC), manganese oxidase (MnxG), formate dehydrogenase (FdoGH and FDH), and carbon monoxide dehydrogenase (CoxLM) displayed distributions indicative of biogeochemical status such as oxidative or nutritional stress, with the potential to be more sensitive than chemical sensors. Enzymes that mediate transformations of atmospheric gases like CO, CO2, NO, methanethiol, and methylamines were most abundant in the upwelling region. We identified hot spots of biochemical transformation in the central Pacific Ocean, highlighted previously understudied metabolic pathways in the environment, and provided rich empirical data for biogeochemical models critical for forecasting ecosystem response to climate change.

Ecological interactions are not uniform across time and can vary with environmental conditions. Yet, interactions among species are often measured with short-term controlled experiments whose outcomes can depend greatly on the particular environmental conditions under which they are performed. As an alternative, we use empirical dynamic modeling to estimate species interactions across a wide range of environmental conditions directly from existing long-term monitoring data. In our case study from a southern California kelp forest, we test whether interactions between multiple kelp and sea urchin species can be reliably reconstructed from time-series data and whether those interactions vary predictably in strength and direction across observed fluctuations in temperature, disturbance, and low-frequency oceanographic regimes. We show that environmental context greatly alters the strength and direction of species interactions. In particular, the state of the North Pacific Gyre Oscillation seems to drive the competitive balance between kelp species, asserting bottom-up control on kelp ecosystem dynamics. We show the importance of specifically studying variation in interaction strength, rather than mean interaction outcomes, when trying to understand the dynamics of complex ecosystems. The significant context dependency in species interactions found in this study argues for a greater utilization of long-term data and empirical dynamic modeling in studies of the dynamics of other ecosystems.

Microbial predators such as choanoflagellates are key players in ocean food webs. Choanoflagellates, which are the closest unicellular relatives of animals, consume bacteria and also exhibit marked biological transitions triggered by bacterial compounds, yet their native microbiomes remain uncharacterized. Here we report the discovery of a ubiquitous, uncultured bacterial lineage we name Candidatus Comchoanobacterales ord. nov., related to the human pathogen Coxiella and physically associated with the uncultured marine choanoflagellate Bicosta minor. We analyse complete 'Comchoano' genomes acquired after sorting single Bicosta cells, finding signatures of obligate host-dependence, including reduction of pathways encoding glycolysis, membrane components, amino acids and B-vitamins. Comchoano encode the necessary apparatus to import energy and other compounds from the host, proteins for host-cell associations and a type IV secretion system closest to Coxiella's that is expressed in Pacific Ocean metatranscriptomes. Interactions between choanoflagellates and their microbiota could reshape the direction of energy and resource flow attributed to microbial predators, adding complexity and nuance to marine food webs.

This article explores how the USA and Japan have aimed to advance connectivity and infrastructure investment in the Indo-Pacific, implicitly or explicitly in response to China's Belt and Road Initiative (BRI). Both actors' vision, strategies, and policies have been rolled out under the banner of the 'Free and Open Indo-Pacific' (FOIP). The article first frames connectivity and the FOIP construct in the context of regional order and great-power relations in the Indo-Pacific. It then provides an in-depth assessment of the different initiatives by the USA and Japan, scrutinizing their progress on the ground, shortcomings, and relevant interlinkages. After an analysis of the logics that inform these connectivity initiatives, the article offers three key axioms and assesses implications for order more broadly. First, the West must fix the gap that often exists between rhetoric and capabilities in the sphere of infrastructure investments. Second, Western actors, including the USA and Japan, need to be clear about objectives. Namely, they must decide whether the aim of connectivity is to compete directly with China or to focus on complementarities and comparative advantages. Third, the USA and Japan need to prioritize connections and spheres of connectivity that are deemed strategically central, at the expense of others. More generally, given the connective logics that key actors currently harness, a fracturing of the region into one of the different orders comprising competing yet overlapping connections beckons., Author(s): Bart Gaens [sup.1] , Ville Sinkkonen [sup.1] Author Affiliations: (1) grid.460544.7, 0000 0004 0620 5576, Finnish Institute of International Affairs, , Helsinki, Finland Introduction The recent 'turn' to connectivity [...]

The occurrence of the Salmon-bellied Racer, Mastigodryas melanolomus (Cope, 1868), on the Isla del Coral in the Pacific coast of Mexico is confirmed through the examination of squamation and the use of other morphological characters. Additionally, we conducted a morphological analysis to assess the differences between M. melanolomus and Masticophis lineatus (Bocourt, 1890), which was previously reported on the island. The results of our analysis suggest a possible misidentification of the previous record. Further investigations and explorations will yield additional insights about whether both species occur on Isla del Coral.

Agonimia gargominyi ( Verrucariaceae , Verrucariales ) is described and illustrated from bark samples collected from Morane atoll (Tuāmotu-Gambier Islands, French Polynesia). It is characterized by the large superficial perithecia having a pale brown-colored ostiolar region, the 8-spored asci, and the relatively large lobed squamules. Micromorphology of the ascomata and the thalline squamules matches the genus Agonimia . Additionally, to accommodate the inclusion of this newly identified species, the existing comprehensive key encompassing all known Agonimia species worldwide has been modified and updated accordingly. Detailed illustrations supplement the description of Agonimia gargominyi .

Excessive precipitation over the southeastern tropical Pacific is a major common bias that persists through generations of global climate models. While recent studies suggest an overly warm Southern Ocean as the cause, models disagree on the quantitative importance of this remote mechanism in light of ocean circulation feedback. Here, using a multimodel experiment in which the Southern Ocean is radiatively cooled, we show a teleconnection from the Southern Ocean to the tropical Pacific that is mediated by a shortwave subtropical cloud feedback. Cooling the Southern Ocean preferentially cools the southeastern tropical Pacific, thereby shifting the eastern tropical Pacific rainbelt northward with the reduced precipitation bias. Regional cloud locking experiments confirm that the teleconnection efficiency depends on subtropical stratocumulus cloud feedback. This subtropical cloud feedback is too weak in most climate models, suggesting that teleconnections from the Southern Ocean to the tropical Pacific are stronger than widely thought.

AbstractKinetic energy associated with inertia–gravity waves (IGWs) and other ageostrophic phenomena often overwhelms kinetic energy due to geostrophic motions for wavelengths on the order of tens of kilometers. Understanding the dependencies of the wavelength at which balanced (geostrophic) variability ceases to be larger than unbalanced variability is important for interpreting high-resolution altimetric data. This wavelength has been termed the transition scale. This study uses acoustic Doppler current profiler (ADCP) data along with auxiliary observations and a numerical model to investigate the transition scale in the eastern tropical Pacific and the mechanisms responsible for its regional and seasonal variations. One-dimensional kinetic energy wavenumber spectra are separated into rotational and divergent components, and subsequently into vortex and wave components. The divergent motions, most likely predominantly IGWs, account for most of the energy at wavelengths less than 100 km. The observed regional and seasonal patterns in the transition scale are consistent with those from a high-resolution global simulation. Observations, however, show weaker seasonality, with only modest wintertime increases in vortex energy. The ADCP-inferred IGW wavenumber spectra suggest that waves with near-inertial frequency dominate the unbalanced variability, while in model output, internal tides strongly influence the wavenumber spectrum. The ADCP-derived transition scales from the eastern tropical Pacific are typically in the 100–200-km range.

Comprehensive knowledge of the distribution of active hydrothermal vent fields along midocean ridges is essential to understanding global chemical and heat fluxes and endemic faunal distributions. However, current knowledge is biased by a historical preference for on-axis surveys. A scarcity of high-resolution bathymetric surveys in off-axis regions limits vent identification, which implies that the number of vents may be underestimated. Here, we present the discovery of an active, high-temperature, off-axis hydrothermal field on a fast-spreading ridge. The vent field is located 750 m east of the East Pacific Rise axis and ∼7 km north of on-axis vents at 9° 50'N, which are situated in a 50- to 100-m-wide trough. This site is currently the largest vent field known on the East Pacific Rise between 9 and 10° N. Its proximity to a normal fault suggests that hydrothermal fluid pathways are tectonically controlled. Geochemical evidence reveals deep fluid circulation to depths only 160 m above the axial magma lens. Relative to on-axis vents at 9° 50'N, these off-axis fluids attain higher temperatures and pressures. This tectonically controlled vent field may therefore exhibit greater stability in fluid composition, in contrast to more dynamic, dike-controlled, on-axis vents. The location of this site indicates that high-temperature convective circulation cells extend to greater distances off axis than previously realized. Thorough high-resolution mapping is necessary to understand the distribution, frequency, and physical controls on active off-axis vent fields so that their contribution to global heat and chemical fluxes and role in metacommunity dynamics can be determined.