Oceanographic Conditions Research Articles

Assessing Satellite-Derived Shoreline Detection on a Mesotidal Dissipative Beach

The accuracy and robustness of the shoreline definition from satellite imagery on different coastal types are crucial to adequately characterising beach morphology and dynamics. However, the generic and widespread application of satellite-derived shoreline algorithms is limited by the lack of robust methods and parameter assessments. This work constitutes a quantitative and comprehensive assessment of the satellite-derived waterlines from Sentinel-2 by using the novel SAET tool (Shoreline Analysis and Extraction Tool) on the exposed and mesotidal beach of La Victoria (Cádiz, SW Spain). The diverse parameters available in SAET, such as water indexes, thresholding methods, morphological filters, and kernel sizes, were combined to define water/land interface positions that were compared against coincident video-derived waterlines. Satellite-derived waterline errors are found to be affected by extraction parameters, as well as by the oceanographic and morphological conditions at the time of the image acquisition. The application of a morphological erosion filter on the water mask, which tends to shift the extracted waterline seawards and reduce bias, is the best solution at the dissipative site of La Victoria Beach. Moreover, using a 3 × 3 kernel size consistently shows higher accuracies than a larger kernel. Although there was no parameter combination showing the best skill for all dates, the employment of the Automated Water Extraction Index for images with no shadows (AWEInsh) with a threshold = 0, erosion morphological filter, and 3 × 3 kernel was, overall, the best combination of extraction parameters for this beach (average waterline RMSE of 5.96 m). The combination of the Modified Normalised Difference Water Index (MDNWI) with the Otsu thresholding also led to similar positions of the resulting waterlines and offered good accuracies. In line with other recent research efforts, our work stresses the lack of generic shoreline extraction solutions that can be applied automatically at a global level and the necessity to adapt and validate the extraction methodologies to the different types of coastlines.

Metabarcoding and microscopy characterization of phytoplankton from frontal areas of the Argentine Sea

The Argentine Sea is worldwide recognized as a highly productive area, characterized by extensive phytoplankton blooms during spring and summer. Despite the well-known importance of frontal areas for biomass accumulation, phytoplankton diversity remains poorly studied. In an unprecedented approach for the Argentine Sea, we combined microscopy and 18Sv4 metabarcoding analyses for a refined assessment of summer phytoplankton composition in three understudied frontal areas of the Argentine Sea (≈43°−55°S), with contrasting oceanographic conditions. Metabarcoding and microscopy analyses agreed on the detection of the dominant phytoplanktonic groups in the different frontal areas studied; chlorophytes in Valdés Peninsula, dinoflagellates in waters off Blanco Cape, and diatoms in de los Estados Island. The analysis of the phytoplankton community was significantly enriched by combining both techniques, microscopy provided cell abundances and biomass data and metabarcoding provided greater detail on species composition, revealing an important specific richness of dinoflagellates, diatoms and other delicate groups, such as chlorophytes. However, we also considered differences between the methods for certain taxa at a lower taxonomic level (species/genus) of the dominant taxa, such as the underestimation of the diatoms Asterionellopsis glacialis and Pseudo-nitzschia spp. and the overestimation of Chaetoceros contortus by metabarcoding in comparison to microscopic counts. The detection of several taxa belonging to small and delicate groups, previously overlooked due to the lack of distinct morphological features, establishes a baseline for future studies on phytoplankton diversity in the Argentine Sea.

Revealing the variety in phytoplankton communities in waters near the Antarctic Peninsula by high-throughput sequencing

ABSTRACT The waters near the Antarctic Peninsula have always been a hot spot because of their variable and unique oceanographic conditions. To distinguish the differences in phytoplankton communities, we conducted a mesoscale survey during the austral summer of 2018. Samples were collected at 14 stations located in the Drake Passage, South Shetland Islands (SSI) and South Orkney Islands (SOI). A total of 615 operational taxonomic units were extrapolated using V4-5 18S rDNA sequencing collected from the chl a max layers. Three groups (I, II, and III) were divided at a similarity level of 60% by multivariate statistical analysis, and there were significant differences between groups II and III. Generally, diatoms and dinoflagellates predominated among all three groups. Chlorophyta was found in greater abundance near the SSI, whereas pennate diatoms contributed more around the SOI. The different abundance of particular dinoflagellates was the reason for grouping by SIMPER analysis. And Pseudochattonella farcimen, Micromonas sp. and Pyramimonas sp were screened out which inducing dissimilarity were less mentioned in other literatures. Temperature and salinity among stations showed little difference in our study. Phytoplankton assemblage was a complex issue and the factors induced the difference of phytoplankton communities need to further analyze.

Distribution of the N2 -fixing cyanobacterium Candidatus Atelocyanobacterium thalassa in the Mexican Pacific upwelling system under two contrasting El Niño Southern Oscillation conditions.

The unicellular cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) is a key diazotroph in the global ocean owing to its high N2 fixation rates and wide distribution in marine environments. Nevertheless, little is known about UCYN-A in oxygen-deficient zones (ODZs), which may be optimal environments for marine diazotrophy. Therefore, the distribution and diversity of UCYN-A were studied in two consecutive years under contrasting phases (La Niña vs. El Niño) of El Niño Southern Oscillation (ENSO) along a transect in the ODZ of the Mexican Pacific upwelling system. Of the three UCYN-A sublineages found, UCYN-A1 and UCYN-A3 were barely detected, whereas UCYN-A2 was dominant in all the stations and showed a wide distribution in both ENSO phases. The presence of UCYN-A was associated with well-oxygenated waters, but it was also found for the first time under suboxic conditions (<20 μM) at the bottom of a shallow coastal station, within the oxygen-poor and nutrient-rich Subsurface Subtropical water mass. This study contributes to the understanding of UCYN-A distribution under different oceanographic conditions associated with ENSO phases in upwelling systems, especially because of the current climate change and increasing deoxygenation in many areas of the world's oceans.

Influence of Oceanographic Parameters on The Results of The Catch of Squid (Loligo sp.) in The Java Sea (WPP-RI 712)

Information on oceanographic conditions is an important aspect to pay attention to because it is closely related to the existence of abundant squid resources. Most types of squid make seasonal migrations in response to changes in temperature. Squids will look for a place to attach their eggs under certain oceanographic conditions, such as the right salinity and water depth. Data collection was carried out primarily in the field using a 5 in 1 salinometer and secondarily using the AQUA MODIS satellite. Sea surface temperatures observed from the end of March to the beginning of May experienced a slow increase in temperature from day to day. Regarding water salinity, the data obtained is that the further out to sea, the greater the salinity tends to be. In chlorophyll a, there was a significant increase in March with the highest distribution. The influence of the measured oceanographic parameters on the number of squid catches, after chlorophyll-a cross-correlation was carried out, was 36.5% or a fairly strong correlation and the other 63.5% was estimated to influence other factors in the form of light, bulla, water depth, and current strength, as well as the crew's skills in operating fishing gear.

Flow measurement in the southern coast of the Caspian Sea

Oceanographic monitoring was conducted in the southern basin of the Caspian Sea to evaluate the physical structure of seawater and sea currents. This monitoring aimed to gather data and analyze the characteristics of the seawater, including temperature, salinity, density, and other relevant parameters. Additionally, the monitoring also focused on studying the patterns and dynamics of sea currents in the region. The collected data and analysis from this monitoring period provided valuable insights into the oceanographic conditions of the southern basin of the Caspian Sea. During storm events, a high level of correlation between the current and wind data was observed in the southern basin of the Caspian Sea during the 2017-2018 monitoring period. The measured current data indicated that the predominant directions were north (N) and northwest (NW). It was observed that strong gusts predominantly originated from the north (N) and northwest (NW) directions. Additionally, a smaller portion of the strong gusts was observed to come from the South-Southeast (S-SE) direction. These findings indicate that the prevailing wind patterns during the monitoring period were primarily from the north and northwest, with a lesser contribution from the South-Southeast direction. The current profiles observed during the monitoring period in the southern basin of the Caspian Sea were primarily influenced by the general circulation pattern of the region. This circulation pattern played a significant role in shaping the current profiles observed during the measurements. In terms of the surface current speed, the maximum recorded value was approximately 200 cm/s, which occurred in January. This indicates that there were instances of relatively high-speed currents in the southern basin of the Caspian Sea during that time. The evaluation of inter-annual variability in vertical structure and seawater temperature profiles during the monitoring period confirmed the presence of seasonal stratification in the water column of the southern basin of the Caspian Sea. This stratification was observed to consist of different layers, including the surface mixed layer, thermocline, and deep-water layers. The formation of these layers is indicative of the seasonal variations in temperature and density within the water column. The vertical changes in the water’s physical parameters during the monitoring period revealed the formation of stratification in the southern basin of the Caspian Sea. In March, it was observed that the water temperature decreased from 11.5°C at the surface to 8.5°C at a depth of 100 m, indicating the presence of a temperature gradient. As the monitoring progressed into May, the stratification became stronger, with the surface water temperature reaching around 23°C. By August, the surface layer of the sea water experienced a significant increase in temperature, reaching 29°C. These observations highlight the development of stratification and the seasonal variations in water temperature during the monitoring period in spring and summer seasons. The water temperature beneath the thermocline layer, specifically at a depth of 100 meters, was recorded to be around 8-8.5 oC. Additionally, the water salinity in the water column exhibited fluctuations between 12-12.5 (psu). Monitoring and understanding physical properties variations are crucial for assessing the oceanographic conditions and their potential impact on marine ecosystems in the southern basin of the Caspian Sea.

Modeling of swordtip squid (Uroteuthis edulis) monthly habitat preference using remote sensing environmental data and climate indices

Understanding the spatial arrangement of species in maritime settings necessitates the study of oceanography. Hence, doing a study on the correlation between oceanography and species dispersion is imperative, considering the impacts of global climate change. The study used a generalized additive modeling approach to analyze the influence of oceanographic conditions on the distribution of swordtip squid in northeastern Taiwan, integrating fishing data, climatic oscillation and oceanography. Among seven oceanographic characteristics, bottom sea temperature (SSTB), sea surface height (SSH), sea surface chlorophyll (SSC), and sea surface temperature (SST) showed significant influence in generalized additive model (GAM) analysis (combined deviance explained: 40.30%). The monthly catch rate of swordtip squid is influenced by six climatic oscillations, with the Pacific Decadal Oscillation having the most significant impact, accounting for 31% of the distribution, followed by the North Pacific Gyre Oscillation at 10.8% and the Western Pacific Oscillation at 6.05%. From 2015 to 2019, the main areas for squid fishing were situated in the northeastern waters of Taiwan, precisely within the geographical coordinates of 25°N to 28°N and 121.5°E to 125°E. This study provides crucial insights for managing swordtip squid fisheries in Taiwan's northwest waters, highlighting the importance of incorporating oceanographic conditions relating to climate change information into decision-making to protect global ocean fisheries and their dependent communities.

Metal content in Sardina pilchardus during the period 2014-2022 in the Canary Islands (Atlantic EC, Spain).

The contamination present in an organism varies depending on biological and oceanographic conditions, so monitoring the same species is of great importance to understand the state of the ecosystem. Fifteen specimens in Sardina pilchardus between 12 and 15cm in total length were collected during the second half of January of each of the study years (2014, 2016, 2018, 2020 and 2022). Samples were analyzed with Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) to measure metals (Al, Cd, Cu, Fe, Li, Ni, Pb and Zn) in mg/Kg. There was a progressive decrease in Pb content over the period, with the highest concentration being obtained in 2014 (0.086 ± 0.065mg/kg). Locally important oceanic-atmospheric events may occur in the study period that strongly impact the tissue composition of marine organisms. In this case, discontinuous trends were evident in some of the metal concentrations analyzed in the muscle of European sardine in the Canary Islands.

A Ten-Year Record Shows Warming Inside the Belize Barrier Reef Lagoon

The Belize Barrier Reef system (BBR) in the western Caribbean’s Gulf of Honduras contains a large region of lagoon coral reef, seagrass and mangrove habitat. As the largest lagoon habitat within the Caribbean, this region experiences differing oceanographic and temperature conditions as compared to deeper offshore areas. The occurrence of several endemic species within the Gulf of Honduras area and inside the Belize lagoon supports the hypothesis that this area is a unique biogeographic region. Consequently, the ecological effects of temperature increase due to global climate change may have a long-term adverse impact on this region’s unique marine species. This study reports an in situ temperature record over a ten-year period (2004–2014) collected from a coral reef offshore of Wee Wee Cay within the South Water Cay Marine Reserve of Belize. There was a steady increase in temperature during the decade.

Assessment of Shoreline Change from SAR Satellite Imagery in Three Tidally Controlled Coastal Environments

Coasts are continually changing and remote sensing from satellites has the potential to both map and monitor coastal change at multiple scales. Unlike optical technology, synthetic aperture radar (SAR) is uninfluenced by darkness, clouds, and rain, potentially offering a higher revision period to map shoreline position and change, but this can only be feasible if we have a better interpretation of what shorelines as extracted from SAR imagery represent on the ground. This study aims to assess the application of shorelines extracted from SAR from publicly available satellite imagery to map and capture intra-annual to inter-annual shoreline variability. This is assessed in three tidally controlled coastal study areas that represent sand and gravel beaches with different backshore environments: low-lying dunes and marsh; steep, rocky cliff; and urban environments. We have found that SAR shorelines consistently corresponded to positions above the high-water mark across all three sites. We further discuss the influence of the scene geometry, meteorological and oceanographic conditions, and backshore environment and provide a conceptual interpretation of SAR-derived shorelines. In a low-lying coastal setting, the annual change rate derived through SAR presents a high degree of alignment with the known reference values. The present study contributes to our understanding of the poorly known aspect of using shorelines derived from publicly available SAR satellite missions. It outlines a quantitative approach to automatically assess their quality with a new automatic detection method that is transferable to shoreline evolution assessments worldwide.

Bayesian Network Analysis for Shoreline Dynamics, Coastal Water Quality, and Their Related Risks in the Venice Littoral Zone, Italy

The coastal environment is vulnerable to natural hazards and human-induced stressors. The assessment and management of coastal risks have become a challenging task, due to many environmental and socio-economic risk factors together with the complex interactions that might arise through natural and human-induced pressures. This work evaluates the combined effect of climate-related stressors on low-lying coastal areas by applying a multi-risk scenario analysis through a Bayesian Network (BN) approach for the Venice coast. Based on the available open-source and remote sensing data for detecting shoreline changes, the developed BN model was trained and validated with oceanographic variables for the 2015–2019 timeframe, allowing us to understand the dynamics of local-scale shoreline erosion and related water quality parameters. Three “what-if” scenarios were carried out to analyze the relationships between oceanographic boundary conditions, shoreline evolution, and water quality parameters. The results demonstrate that changes in sea surface height and significant wave height may significantly increase the probability of high-erosion and high-accretion states. Moreover, by altering the wave direction, the water quality variables show significant changes in the higher-risk class. The outcome of this study allowed us to identify current and future coastal risk scenarios, supporting local authorities in developing adaptation plans.

Biodiversity patterns of the benthic macrofaunal communities across the intertidal sedimentary shores of two Antarctic islands

Antarctic benthic ecosystems support a unique fauna characterized by high levels of diversity and endemism. However, our knowledge of the macrofauna communities across the Antarctic intertidal sedimentary shore is limited, and their fundamental ecological features, including spatial variability, remain poorly understood. This study aimed to investigate the abundance, community structure (i.e. taxa-specific abundance), and biodiversity patterns (α-, β-, and λ-diversity) of benthic macrofauna communities on intertidal sedimentary shores of two Antarctic islands (South Shetland archipelago, N of Antarctic Peninsula): Livingston and Deception. We conducted a quantitative sampling during two Austral summer campaigns (2004 and 2005), studying eleven intertidal sites, with five sites located on Livingston and six on Deception. Our results demonstrated a significantly higher abundance of intertidal benthic macrofauna communities on Livingston than on Deception. Furthermore, significant differences in community structure were observed between the two islands. In terms of biodiversity patterns, there were no significant differences in the number of taxa within communities (α-diversity) between the two islands. However, significant differences in the variation of community composition (determined by the number and identity of taxa) between intertidal sites (β-diversity) were observed, shedding light on the higher total taxa count (λ-diversity) on Livingston compared to Deception. We suggest that the island-specific characteristics (e.g., granulometric characteristics, ice disturbance, sedimentation rates, and geothermal activity) determine the differences observed in macrofauna communities. However, other ecological processes and factors are operating on different spatial and temporal scales (e.g., population dynamics, biotic interactions, oceanographic conditions, and climate change) that influence the occurrence and abundance of macrofaunal taxa. Our findings contribute to the fundamental understanding of the spatial variability of these communities and provide essential information for better management decisions and conservation practices in Antarctic coastal ecosystems.

Integrating Sentinel-2 and PlanetScope Image with Drone-based Seagrass Data for Seagrass Percent Cover Mapping

Seagrass field data collection activities to train remote sensing images for seagrass percent cover mapping and assess its accuracy can be laborious, costly, and time-consuming, especially for vast seagrass meadows with high density variations. There is also a potential discrepancy in information between seagrass data collected in the field, which usually covers 0.25m2 or 1m2 ground area, and the spatial resolution of remote sensing image used. PlanetScope at 3m and Sentinel-2 at 10m are the currently frequently remote sensing images used to map seagrass. There is a considerable information gap between seagrass data collected in the field and their spatial resolution. The use of seagrass field data thus involves a generalization process and a set of assumptions to justify its integration with remote sensing image. An alternative is to use the drone-based aerial image (hereafter drone data), which captures seagrass meadows at very high spatial resolution, to interpret seagrass percent cover at a level of precision similar to the remote sensing data used. This research assessed the integration of drone-based seagrass data with PlanetScope and Sentinel-2 images to map seagrass percent cover. Seagrass percent cover was interpreted from drone data for each 9m2 and 100m2 ground size following the PlanetScope and Sentinel-2 grids, respectively. Stepwise, random forest, and support vector regression were employed to develop the seagrass’s percent cover mapping model. The accuracy assessment of the resulting seagrass percent cover map involves the calculation of RMS error and plot 1:1 and its derivative analyses. Our results showed that an unparalleled benefit of using drone data is the possibility to obtain SPC information that matches the spatial resolution of satellite imagery, where techniques such as photo-quadrat and photo-transect cannot match. Drone data is successfully integrated with PlanetScope and Sentinel-2 images to produce a high accuracy SPC map effectively and efficiently. Indeed, there are challenges in using drone data, mainly related to oceanographic and weather conditions, and the difficulties in interpreting SPC at the species level.

Developments in Metocean Information in Support of US Offshore Wind Energy and the Ocean Sciences

Strong growth of offshore wind energy development is driving demand for better characterizing meteorological and oceanographic (metocean) conditions where physical data are traditionally sparse. Most offshore wind energy structures extend from the seafloor up through the full water column and into the atmosphere to heights approaching 300 m. This requires a comprehensive understanding of anticipated waves, swells, currents, and weather over the life cycle of offshore wind energy projects. This paper describes the relevance of key metocean parameters and analyses to the offshore wind energy field and examines the opportunities and challenges that may be encountered by metocean initiatives, particularly in the United States where offshore wind energy is in the early stages of development. We also suggest ways in which offshore wind energy driven metocean activities can reap spin-off benefits to broader oceanographic interests.

Early Warning of a Cold Wave in the Gulf of Maine

Oceanographic changes are occurring more rapidly in recent decades, with new implications for ocean ecosystems and adjacent human communities. It is important to bring attention to these changes while they are unfolding rather than after they have occurred. Here we report on a rapid shift toward colder, fresher water in the deep Gulf of Maine that, as of mid-June 2024, has persisted for at least six months. The shift likely represents an influx of Labrador Slope Water and resembles conditions that predated a major warming shift that occurred in 2011–2012. Deep-water oceanographic conditions in the Gulf of Maine have a strong influence on ecosystem dynamics, including the prey of critically endangered North Atlantic right whales, the seasonal and disease dynamics of American lobster, and the distribution and abundance of kelp forest communities, among others. Oceanographic surprises have an important role in this system, and monitoring how this shift unfolds, oceanographically and ecologically, will give new insights into how oceanographic signals can inform our understanding of ecosystem responses.

Особенности экологического состава планктонных и бентосных фораминифер в поверхностных осадках Татарского пролива (Японское море)

he fauna of planktonic and benthic foraminifera of the Tatar Strait in the surface layer of sediments from cores sampled during the cruise LV85 on the R/V «Akademik Lavrentiev» in May 2019 has been studied. The benthic foraminifera assemblages, consisting of living and dead shells, correspond in their ecological appearance to the modern cold-water oceanographic conditions of the studied area. Among planktonic foraminifera, along with the dominant subarctic form Neogloboquadrina pachyderma dex., there are single tropical and subtropical species (Globorotalia inflatа, Globigerinoides ruber and Neogloboquadrina dutertrei). The authors believe that the above warm-water forms entered the Tatar Strait from the southwestern part of the Sea of Japan with the warm waters of the Tsushima Current. Fossil finds of warm-water fauna in Pleistocene and Holocene sediments play an important role in deciphering the geological record in the northern part of the Sea of Japan. Their presence in sedimentary sections makes it possible to trace the northward migration of the warm current and assess the extent of its influence on coastal ecosystems in the past.

Potential invasive species detection of Demospongiae using environmental DNA in Sabang and Lhokseumawe Ports

Sabang and Lhokseumawe Ports are located in the province of Aceh and constitute part of the northern Malacca Strait, sharing direct borders with neighboring countries such as Malaysia, Thailand, and India. Strategic geographical location significantly influences the oceanographic conditions and biodiversity of the area. As marine organisms, sponges play a crucial role in the ecosystem, yet research on their identification in the Sabang and Lhokseumawe regions is limited. The analysis of community structure and identification of species can be conducted using various approaches, including environmental DNA (e-DNA) analysis. This study aimed to assess water quality and identify the presence of potentially invasive Demospongiae using DNA Metabarcoding in Sabang and Lhokseumawe Ports. The measurement results of the water conditions indicate that the waters around Sabang and Lhokseumawe ports generally exhibit values that support sponge life. e-DNA analysis successfully detected the presence of the Demospongiae class, with 260 Operational Taxonomic Units (OTUs) in Sabang waters and 148 OTUs in Lhokseumawe waters. One commonly found genus, Cliona sp., has the potential to become invasive in both locations, posing a risk of bioerosion to corals under specific conditions.

Characterizing oceanographic conditions near Coiba Island and Pacific Panama using 20 years of satellite-based wind stress, SST and chlorophyll-a measurements

Coiba Island and the associated Special Zone of Marine Protection represent an important, yet poorly studied marine reserve along the Pacific coast of Panama. While efforts have recently began to establish monitoring programs in the region, a range of historical, marine-related environmental measurements already exist, derived from satellite-based observations. The goal of this paper was to use long-term datasets for key variables to provide qualitative insights (i.e. descriptive oceanography) of climatological conditions and interannual variability in the Pacific Panama region. These are underpinned with numerical assessments, providing an important baseline for ongoing and future studies, particularly in the Coiba Island/Gulf of Chiriqui region. In particular, we examined 20 years (January 2003-December 2022) of wind stress, sea surface temperature (SST), and chlorophyll-a (Chl-a), spanning the neritic and pelagic regions of the Pacific Panama coast. During the dry season (northern winter), the well-known, seasonal, regional Panama wind jet appeared across the Gulf of Panama, leading to surface mixing and SST cooling that eventually extended across most of the Panama Bight. West of the Azuero Peninsula, SST increased and surface warming extended further offshore from January through April. The SST in the Gulf of Chiriqui during this period was about 1 °C warmer on average than east of Coiba Island. By July and August, offshore SST gradients became largely longitudinal, cooling occured across the season, and the SST on either side of Coiba Island was nearly the same. The influence of the Panama jet in the Gulf of Panama was clear in the Chl-a data as well, with upwelling-driven values peaking in February/March (up to 11 mg m-3, with a monthly climatological value of around 2 mg m-3 during this period). During the rest of the year, the Chl-a concentration in this region averaged around 0.5-1.0 mg m-3. In the Gulf of Chiriqui and the region east of Coiba Island, the climatological monthly averages were roughly 0.3-0.5 mg m-3 and 0.4-0.6 mg m-3, respectively. Somewhat surprisingly, very high Chl-a values were present in the satellite data for the Gulf of Chiriqui during May 2007 and June 2008, peaking at 16 mg m-3 and 32 mg m-3 at a location just west of Coiba Island, respectively. It remains unclear as to the cause of these apparent blooms. Even when the high Chl-a values were excluded in the calculation of climatological averages in the Gulf of Chiriqui, however, there is a suggestion of modest seasonality in Chl-a values, with slightly elevated values (~ 0.4 mg m-3) peaking around May and October. During the extreme El Niño event of 2015-2016, the monthly-averaged SST along the Panama Pacific coast was warmer than average, with elevated levels of up to + 2 °C and lasting 12 months in the Gulf of Chiriqui. In the Gulf of Panama, the monthly-averaged SST anomalies were up to + 1.7 °C, although the temperatures returned to near-seasonal averages after roughly 5 months.

A review of the oceanographic structure and biological productivity in the southern Okhotsk Sea

The southern Okhotsk Sea is one of the best fishing grounds in Japan, and the biogeochemistry, primary productivity, and physical aspects of this region have been heavily researched. However, a comprehensive review of the literature has not been written since that by doctor Takatoshi Takizawa more than 40 years ago (1982). This review actualizes the share–ground knowledge of the influence of oceanographic conditions on the primary productivity of the area. This review includes topics from physical/chemical oceanography and hydrobiology, focusing on the complex oceanological structures that support the high primary productivity of the southern Okhotsk Sea. It is known that the formation of all water masses is ultimately a consequence of the seasonal interchange of the Soya Warm Current and the East Sakhalin Current. However, it was revealed that there may be over- or under-estimations in different material and heat fluxes among water masses, especially regarding the dense Soya Warm Current. Recent studies have investigated the formation mechanisms of different water masses using chemical tracers, particularly radionuclides. Although promising if properly combined with traditional techniques, more isotopes or compounds are required to derive further conclusions. In terms of biological aspects, the high seeding potential of Thalassiosira after sea ice melting has been featured by many authors, and it was considered as the reason for its highest abundance in spring. The total carbon mass flux, which is essential for scallop farming, is highest in April–June, normally 120–160 mg C m−2day−1. The total carbon mass flux is maximum (up to 1165 mg C m−2day−1) after the spring bloom peak, and the spring bloom is strongly linked to sea ice retreatment. It was identified that the routes of 134Cs towards the Intermediate Cold Water, the formation mechanism of the Cold Water Belt, and the solubilization process of sea ice-carried particulate Fe require further research. Three major potential threats were identified, including the appearance of alien toxic species, a decrease in sea ice production in the northern parts of the Okhotsk Sea, and offshore gas and oil drilling northeastern of the Sakhalin Island. Publicly available scientific knowledge about the biogeochemistry of the southern Okhotsk Sea and its relationship with its rich primary productivity was actualized to 2022, anticipating that this work will become the starting line for many early career scientists endeavoring in interdisciplinary studies.

Revisiting the Yudongzi microbialites (basal Triassic, northwestern Sichuan, South China): Fabric textures and paleoenvironmental implication

Unusual sedimentary deposits such as stromatolites, thrombolites, dendrolites, and giant ooids are widely distributed in the Permian–Triassic boundary (PTB) successions of shallow platform facies worldwide. These microbial fabrics, however, are rarely present in the same section. The genesis of these PTB microbialites and the oceanographic conditions linking to the end-Permian mass extinction still remain disputed despite intense study. Here, we report a stromatolite-dendrolite-thrombolite-giant ooid association from the PTB beds of the Yudongzi section on the northwestern margin of the Yangtze Platform, South China, which was situated in low latitudes during the Permian-Triassic (P-Tr) transition. The Yudongzi microbialites rest on an irregular contact with underlying Permian bioclastic limestone and are comprised of lower bedded stromatolite, digitate dendrolite, upper bedded stromatolite, and thrombolite units. The bedded stromatolite is characterized by undulating laminated structures and various amalgamated and layered clots. The digitate dendrolite is made up of digitate-like branches, formed by clots distributed in an arched arrangement, and characterized by abundant branching dendroids. The thrombolite displays distinct clotted textures that comprise a mixture of dark-colored microbial fabric and light-colored interstitial sediment. In microbialite, columnar structures identified as Gakhumella-like calcimicrobe are very abundant. Each individual of Gakhumella-like structure has densely arranged segments forming a columnar- to fan-shaped micro-structure. Single segments are arch-shaped and form a thin chamber between segments. Coccoid-like, bacterial clump-like, and other spheroidal aggregates are also commonly present and suggestive of a biogenetic origin for the Yudongzi microbialites. Moreover, distinct aragonite crystal fans are also for the first time found in the PTB microbialites in South China, suggesting that the fans may have resulted from high inorganic carbon concentrations, and thus high levels of carbonate dioxide in the seawater. The Yudongzi microbialites are capped by shelly grainstone and a massive giant oolite, implying that the demise of the Yudongzi microbialites may be due to destruction by strong wave currents in a high energy setting. Some ooids are coated unevenly by micritic laminae (or envelopes) indicating the possibility of a microbe-related origin. These microbial-coated giant ooids, together with the massive microbialites, may imply the long-term of microbial bloom in the oceans immediately after the end-Permian extinction. The co-existence of abundant Gakhumella-like microorganisms and oxygen-dependent invertebrates, together with some coccoid-like spheroids, aragonite cement crystal fans, and pyrite framboids indicative of oxygen-poor conditions, implies that oxygenation state of the PTB microbialites is much more complex than previously recognized, demonstrating need for continued multidisciplinary examination of facies changes associated biotic mass extinction.