Accurate estimation of mixed layer depth (MLD) is crucial for understanding the upper ocean dynamics as well as their implications on climate and marine ecosystems. While various methods have been proposed to estimate MLD from vertical temperature and/or density profiles, a systematic evaluation across different algorithms remains untapped. In this study, twelve approaches for MLD estimation are implemented

The Sicily Channel plays a crucial role in the general circulation of the Mediterranean Sea. However, the internal wave dynamics is still sparsely characterized in this area which is a hotspot for internal tides. Here, we benefit from a high-resolution model of the Mediterranean Sea with and without tidal forcings to study the synoptic internal wave dynamics in the Sicily Channel area as well as their

Carbon export through the Arctic rivers could significantly impact land–ocean interactions and coastal ecosystems under global warming. However, the transport dynamics and coastal fate of these carbon associated with large river plumes on the adjacent shelves remain largely unknown, particularly under large-scale climate patterns like the Arctic Oscillation (AO). In this study, we analyzed the interannual

By resolving spatiotemporal variations in sea surface partial pressure of CO2 (pCO2) based on multiple-year underway measurements, we quantified basin-scale air–sea CO2 exchange flux on the China side of the South Yellow Sea between 2005 and 2011, and compared it with the result obtained between 2011 and 2018. Over the three subregions under study, the area-weighted average of the CO2 influx rate was

There is growing concern among decision makers in a warming world that increasing frequency and severity of extreme events, such as marine heatwaves, is making historical information less representative and useful. To aid decision making in a rapidly warming ocean, researchers have developed new forecast tools that can predict marine heatwaves on sub-seasonal to seasonal timescales. As demand from

The continental seas have experienced significant eutrophication due to intensified anthropogenic activities. This study aims to elucidate the processes that govern the budgets of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved silicate (DSi) in the East China Sea (ECS). Key nutrient sources include terrestrial runoff, atmospheric deposition, water column regeneration

Patterns of the spatial fluxes and conversion of oceanic kinetic energy are explored using a 26-year temporal average of a dynamically consistent ECCO state estimate. Because thermal-wind balance is found to be accurate over much of the ocean domain, and with correspondingly small Rossby numbers, a linear analysis is used. Despite the averaging the abyssal ocean average proves remarkably noisy, and

The ocean absorbs anthropogenic CO2 and sequesters it in deep water through the marine biological pump, playing an irreplaceable role in global climate change. This study investigates the vertical distribution of CO2 system parameters in the deep Eastern Indian Ocean during autumn 2020 and spring 2021. Additionally, the role of biological processes in regulating the CO2 system parameters were examined

A new species of the genus Bathyopsurus Nordenstam, 1955 (Munnopsidae, Bathyopsurinae) is described from the Aleutian Trench in the North-east Pacific collected during the RV Sonne expedition AleutBio (Aleutian Trench Biodiversity Studies) (SO293) from depths between 4224–5170 m from both the northern sub-Arctic slope as well as the southern North Pacific slope of the Aleutian Trench. Bathyopsurus

We investigated the taxonomic and functional complexity of a mesozooplankton community and associated trophic relationships in a tropical area of the Southwest Atlantic Ocean. Mesozooplankton communities showed a clear distribution between coastal and oceanic regions. Along the continental shelf, areas influenced by the upwelling of the Cabo Frio and plume of the Paraíba do Sul River, characterized

The oceans have absorbed nearly 30% of the anthropogenic CO2 that alters the ocean carbon chemistry. The oceanic processes are highly complex, which mandate approaches that couple its physical, chemical and biological states. Here, we use a coupled atmosphere–ocean-biogeochemistry model, incorporating spatially and temporally varying atmospheric CO2 to simulate the north Indian Ocean (NIO) carbon dynamics

The oceanic particle flux controls, in part, ocean biogeochemical cycles and long-term carbon sequestration. The Oceanic Flux Program (OFP), the longest running time series of its kind, has continuously measured the deep particle flux in the oligotrophic Sargasso Sea southeast of Bermuda since 1978. This paper describes the deep flux climatology at the OFP site over the 1978–2022 time period. Mass

The Aleutian Trench, a canyon-like structure in the deep sea floor that parallels the southern fringe of the Aleutian Islands off Alaska, has only been studied by a few previous expeditions. The trench itself and the adjacent island archipelago both present potential dispersal barriers to marine species, which may shape the regional biogeography. We report new findings on the molluscan fauna of the

The Western Tropical Pacific Ocean has a complicated circulation system and plays a significant role in regulating global marine nitrogen cycles and budgets. Powerful insights can be gained by using nitrate isotope (δ15N-NO3- and δ18O-NO3-) techniques. In this study, nitrate concentrations and δ15N-NO3- and δ18O-NO3- values were obtained along meridional (130°E) and zonal (20°N) transects in the Western

Hypoxia events driven by the onshore advection of oxygen-poor upwelling waters have become increasingly common along Eastern Boundary Upwelling Systems (EBUS). More frequent or intense drops in nearshore oxygen concentrations can impact the behavior, population dynamics, and geographic distribution of many coastal species. To better understand these effects, it is necessary to determine the periodicity

Double-diffusive convection (DDC) is a critical driving mechanism for diapycnal mixing in the ocean. However, there is limited quantitative investigation on the impacts of dynamic ocean-atmospheric processes, such as the interaction between tropical cyclones and mesoscale eddies, on DDC generation. In this study, we analyzed the cyclone-eddy induced DDC based on measurements obtained by an underwater

Atlantic salmon (Salmo salar) experienced drastic population declines from the mid-1970 s to the early 1990′s throughout their range. The survival of the salmon while at sea is considered as the main driver of these declines, even though the underlying mechanisms are poorly understood. This study aims at improving the general understanding of the ocean distribution and migration timing of sub-adult

The export of phytoplankton-synthesized particulate organic carbon (POC) from the upper ocean to the depth removes CO2 from the atmosphere, playing a critical role in the global climate system. However, substantial data and knowledge gaps in the spatial and temporal variability of the POC export hamper a full spectrum of understanding to the controls of POC export at both seasonal and basin scales

Preserving healthy marine ecosystems is crucial for human societies, especially in resource-dependent locations like Santo Antão, the most northwestern island of Cabo Verde (East Atlantic Ocean). However, effective conservation requires baseline ecological knowledge on target ecosystems, which is often lacking. This study provides the first ecological characterization of upper mesophotic coral assemblages

The Indonesian Seas feature a wide spectrum of variations in hydrography and circulation. This study applies a simple frequency-based time series decomposition method on the 20-year (2000–2019) model simulation, revealing the spatial distribution of the variations in intra-seasonal, semi-annual, annual, and inter-annual bands, respectively. K-means clustering based on the decomposed variability is

Unicellular plankton are the foundation of marine food webs and biogeochemical cycles. This study analyzed long-term observations (2009–2021) of the taxonomic composition and size structure of nano- to microplankton in the East China Sea to assess the impact of environmental changes on these communities. Over the past decade, aloricate ciliate and chain-forming diatom abundances have declined, likely

Studies on species’ functional traits are increasingly used to explore the links between zooplankton community structure and ecosystem functioning. This study investigates copepod diversity across the main frontal types along the continental shelf and shelf break of eastern South America (32°S-55°S), using taxonomic and functional diversity approaches. We analyzed 53 copepod species grouped by five

Tropical cyclones modify the upper ocean due to significant mixing associated with increased winds that bring CO2 and nutrient-rich subsurface waters to the surface, altering CO2 flux and biological production. In the region where considerable river discharge occurs with strong stratification, it is hypothesized that tropical cyclones may increase the sink of CO2 into the ocean and vice versa in the

The western North Atlantic Subtropical Gyre comprises the warm Gulf Stream (GS) and the cold Deep Western Boundary Current (DWBC), which are the main currents of the Atlantic Meridional Overturning Circulation (AMOC). Hydrographic sections conducted at 66°W (A22) and 52°W (A20) in the western North Atlantic Subtropical Gyre (NASG) have sampled these currents in 1997, 2003, 2012, and 2021. Both single-

The Indian Ocean (IO) is characterized by large gradients in atmospheric aerosols and is also an important sink region for atmospheric CO2. However, there are major gaps in our understanding of the linkages between micronutrient dissolved iron (DFe) derived from aerosol over the IO, and the responses of phytoplankton, uptake of CO2 by the upper ocean, and subsequent CO2 sequestration. The present study

Understanding tidal energetics is crucial for comprehending complex oceanic processes in the South China Sea (SCS). Tidal energy budget in different parts of the world’s oceans has been widely estimated, but the dissipation pathways of tidal energy in the eddying ocean remain elusive. Based on a well-validated high-resolution numerical simulation, this study provides an updated estimate of tidal energy

In polar and temperate regions seasonality in environmental conditions is an important driver of animal phenology. In tropical systems, where the environment is relatively homogeneous year-round, the link between phenology and seasonality is weakened, and many species breed asynchronously or even year-round. This leads to the question of how these species adapt to seasonal changes, which remain present

Several large-scale studies have examined the spatial and temporal (seasonal and interannual) variability in macrozooplankton communities in the eastern Indian sector of the Southern Ocean. In this study, variability in these communities was analyzed using samples collected by the RMT8 during the KY1804 survey, conducted between 80° and 150° E during the austral summer of 2018–2019. Furthermore, these

The Barents Sea is a productive region that is experiencing significant climatic fluctuations, making it essential to assess the impact of warming on the local ecosystems by summarizing information on different ecosystem components during various conditions and preceding trends. Our study aimed to reveal spatial patterns in the distribution and structure of zooplankton assemblages along a latitudinal

This study investigates sea level changes in the Red Sea over the last 29 years (1993–2021) by analyzing long-term trends and interannual variations in the total sea level anomaly (SLA). The study also explores the role of thermosteric and halosteric changes and interannual variability of total SLA using an empirical orthogonal function (EOF) analysis and their relationship with large-scale climate

Internal ocean waves, such as internal tides and internal solitary waves (ISWs), have strong horizontal and vertical velocities and play an important role in ocean energy and material exchange. Field observations indicated that internal waves had a significant effect on hydrodynamics and sediment transport on the continental shelf. However, there remained a lack of field observations on how internal

Changes in phytoplankton composition and abundance are controlled by multiple factors, including physical forcing and nutrient stoichiometry. This study seeks to assess the interplay between the environmental and biogeochemical conditions in shaping the phytoplankton community structure in open ocean waters off western Patagonia. For this purpose, we used biological, hydrographic, and chemical data

Xenophyophores are an abundant component of the megafauna in parts of the equatorial and temperate North Pacific, but few records exist of these giant agglutinated foraminifera in northern North Pacific and adjacent waters. Here, we present a preliminary survey of xenophyophores from the bathyal Bering Sea (∼3500 m depth) and at abyssal depths (4294–6555 m) adjacent to the Aleutian Trench, based on

The genus Axinulus is the richest in species number and quantitative abundance among representatives of the family Thyasiridae, which is found in the abyssal and hadal zones of the deep-sea areas of the northern Pacific Ocean. Many species of the genus form abundant populations and dominate the benthic communities of these deep-sea areas. The study of the material of bivalves collected by the “AleutBio”

The understanding of sea level variability is fundamental for coastal communities with high population density. As important parts of sea levels, tides are often overlooked because they tend to be regarded as simple periodic oscillations by numerous studies. In fact, due to the interference of various non-astronomical factors, observed tides are non-stationary and display multi-time scale variability

Two hydrographical shifts observed within the last two decades around north/northwestern Iberia, in the mid-latitudes of the eastern North Atlantic, reveal a contrasting behaviour of the weakly circulating reservoir known as the intergyre region. In 2005, a strong winter mixing caused an abrupt salinity increase at mid-depths corresponding to East North Atlantic Central Waters core levels (300–500

The invasion and continued expansion of snow crab in the Barents Sea have provided the area with a new and valuable resource. On the negative side, this invasion may lead to changes in the ecosystem, including structural changes and shifts in energy pathways, as we generally view invaders as a problem. We investigated potential effects of snow crab invasion by applying an end-to-end ecosystem model

The Agulhas Current is the strongest western boundary current (WBC) in the Southern Hemisphere with a significant impact on the global climate. Through the Agulhas leakage, it transports warm, saline waters into the South Atlantic Ocean. In recent years, a warming trend has been highlighted in the Agulhas Current, with possible implications for dissolved oxygen ([O2]) due to the link between warming

We measured seasonal variations in dissolved organic carbon (DOC) and total dissolved amino acids (TDAA)—a major component of bioavailable dissolved organic matter (DOM)—in the continental shelf water of the northwestern Pacific marginal seas, including the Yellow Sea and East China Sea. We show that the TDAA concentrations, especially L-amino acids (L-AA), are predominantly dependent on phytoplankton

Marine heatwaves (MHWs), prolonged periods of unusually high ocean temperatures, significantly impact global ecosystems. However, there is ongoing debate regarding the definition of these extreme events, which is crucial for effective research and communication among marine scientists, decision-makers, and the broader public. Fundamental to all MHW analyses is a clearly defined background oceanic climate

Langmuir circulation (LC) and geostrophic effects are crucial physical processes that affect upper-ocean mixing. This study investigates the impact of LC on ocean mixing with a particular focus on geostrophic effects. By combining feedforward neural network (FNN) and Large Eddy Simulation (LES), this study simulated the interaction between varying intensities of LC and different geostrophic effects

As climate change is already altering ocean temperatures, there is an urgent need to understand how environmental changes will affect marine ecosystems. Although great efforts have been made to understand the impacts of ocean warming, there are still uncertainties regarding effects on lower trophic levels and how these may propagate to higher trophic levels. In this study, physics from three different

Quantification of abundance and food consumption of seabirds are key to understand characteristics and ecological functions of local marine ecosystem due to their abundance and diversity in foraging areas, habitat, behavior, mobility and prey types. This study aimed to quantify seabird abundance in pelagic areas in the eastern Indian sector of the Southern Ocean (80–150°E) based on an at-sea observational

The Kuroshio has been long thought to be disadvantageous as nursery grounds for larval fishes due to the low plankton standing stocks under the oligotrophic conditions. Despite of the potential risk for survival and growth, early life stages of various fishes appear abundantly in the Kuroshio and its neighboring waters. Here, we report what kind of taxonomic groups establish community structure of

Ocean warming can affect plankton both directly, through altered metabolic activities, and indirectly, modifying the physical–chemical properties of the water column, with possible effects on ecosystem functioning. To evaluate the combined action of warming-related physiological responses and environmental changes on plankton functioning, we carried out a long-term analysis (from 1994 to 2019) of the

Euphausiids (krill) are globally significant zooplankton prey for many commercially important or endangered predator species. In the productive upwelling system of the Northern California Current (NCC), two krill species, Euphausia pacifica and Thysanoessa spinifera, dominate the preyscape and constitute an important food resource for many seabirds, cetaceans, and fish. In this study, we use five years

Despite numerous studies on mercury in Arctic biota, data from inaccessible, ice-covered regions − especially during the polar night and late winter − remain scarce. This scarcity results in poor understanding of the seasonal dynamics of mercury within the food web. From the Northern Barents Sea, we quantified total mercury and the dietary descriptors δ15N and δ13C as long-term dietary signals (weeks

To protect marine ecosystems threatened by climate change and anthropic stressors, it is essential to operationally monitor ocean health indicators. These are metrics synthetizing multiple marine processes relevant to the users of operational services. In this study, we assess whether selected ocean indicators simulated by operational models can be effectively constrained (i.e., controlled) by biogeochemical

The skin of the ocean is often slightly cooler than the surface mixed layer due to net surface heat loss (cool skin effect), and sometimes slightly warmer in areas with extreme solar radiation (warm layer effect). In previous work (Yang et al., 2022), with the skin temperature correction term (ΔT) derived from the fifth generation European Center for Medium-Range Weather Forecasts Reanalysis (ERA5)

The biologically productive Northern Gulf of Alaska (NGA) continental shelf receives large inputs of freshwater from surrounding glaciated and non-glaciated watersheds, and a better characterization of the regional salinity spatiotemporal variability is important for understanding its fate and ecological roles. We here assess synoptic to seasonal distributions of freshwater pathways of the Copper River

Wind-driven equatorial Kelvin, Rossby, and Yanai waves are known to propagate vertically, as well as zonally, and packets of them can form “beams” that descend into the deep ocean along ray paths consistent with wave-group theory. Here, we obtain analytic solutions to a simplified ocean model that provide a more complete description of beam properties and dynamics than in previous studies.

Global warming affects marine ecosystems by changing environmental conditions, ecosystem structure, and ecosystem functioning. In parts of the Arctic, increased sea temperature and decreased sea ice have led to a poleward expansion of boreal species and increased their interactions with native Arctic species. To investigate and quantify the changing interactions in an Arctic marine food web under new

Across the Newfoundland and Labrador (NL) continental shelf, sub-surface temperatures remain below 0°C throughout the summer, when the surface is much warmer. This oceanographic feature is known as a cold intermediate layer (CIL), and its properties are assessed annually in the region to support ocean climate research and fisheries management. Monitoring in this region is either too infrequent or too

Large amounts of freshwater and nutrients pass through the Bering Strait to the Arctic Ocean, making the Bering Sea a crucial marginal sea of the North Pacific Ocean. The hydrography and biological production of the Bering Sea are strongly influenced by the amount of sea ice produced and melted. The sea ice extent and production exhibited large interannual variability but no visible trend until 2016

The deep sea, Earth’s largest biome, harbors numerous unknown species. Prior to the AleutBio (Aleutian Trench Biodiversity Studies) expedition from July to September 2022, the Northeast (NE) Pacific at abyssal and hadal depths was virtually unexplored. Our study presents new findings from the AleutBio project on the macrofaunal composition of the Bering Sea (BS) and Aleutian Trench (AT) collected by

Phytoplankton responses to typhoons are pivotal for understanding the impact of climate change on marine biodiversity and productivity, yet current literature, focusing on typhoon-induced biomass increases from nutrient dynamics, might overlook the complexity of plume-upwelling interactions during such events. This study, therefore, examines the sequential impact of Typhoons Bailu and Podul on phytoplankton

Phytoplankton elemental composition regulates the efficiency of energy and material transfer in the interface between phytoplankton and their consumers. The ratio of particulate organic carbon to particulate organic nitrogen (POC:PON) shows considerable regional deviations from the canonical Redfield ratio in the global surface ocean. However, in certain oceanic regions such as the northwest Pacific