Pub Date : 2025-07-31DOI: 10.1016/j.dsr.2025.104561
Mengting Zhuo , Yu Hong , Yuhong Zhang , Jiping Liu , Lingqiao Cheng , Guoping Zhu , Song Hu , Yan Du
Polynyas play an important role in climate change by enhancing heat and material exchange between the atmosphere and the ocean in polar regions. This study investigated the influence of strong winds and warm deep water on the Amundsen Sea Polynya (ASP), with a particular focus on ASP events during the winter of 2014. The ASP is located directly above the underwater Bear Ridge, with its shape corresponding to the topography. The ASP is more frequently observed on the eastern side than on the western side, due to the influence of the iceberg chain (fast ice) east of the ASP and prevailing southeast winds. However, we found that the occurrence frequency of the ASP is highest in the shallowest points of the topography, rather than near the iceberg chain on the easternmost side. This is related to the upwelling of warm deep water driven by topography. The upward mixing of warm water with the surface waters inhibits sea ice formation and growth there, helping to maintain the ASP on the east side of the Bear Ridge top. Given the potential for a warmer subsurface ocean around Antarctica in the future, enhanced warm deep water mixing could further impact the thermodynamics of the ASP.
{"title":"Combined influence of strong winds and warm deep water on the formation of Amundsen Sea Polynya in winter","authors":"Mengting Zhuo , Yu Hong , Yuhong Zhang , Jiping Liu , Lingqiao Cheng , Guoping Zhu , Song Hu , Yan Du","doi":"10.1016/j.dsr.2025.104561","DOIUrl":"10.1016/j.dsr.2025.104561","url":null,"abstract":"<div><div>Polynyas play an important role in climate change by enhancing heat and material exchange between the atmosphere and the ocean in polar regions. This study investigated the influence of strong winds and warm deep water on the Amundsen Sea Polynya (ASP), with a particular focus on ASP events during the winter of 2014. The ASP is located directly above the underwater Bear Ridge, with its shape corresponding to the topography. The ASP is more frequently observed on the eastern side than on the western side, due to the influence of the iceberg chain (fast ice) east of the ASP and prevailing southeast winds. However, we found that the occurrence frequency of the ASP is highest in the shallowest points of the topography, rather than near the iceberg chain on the easternmost side. This is related to the upwelling of warm deep water driven by topography. The upward mixing of warm water with the surface waters inhibits sea ice formation and growth there, helping to maintain the ASP on the east side of the Bear Ridge top. Given the potential for a warmer subsurface ocean around Antarctica in the future, enhanced warm deep water mixing could further impact the thermodynamics of the ASP.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104561"},"PeriodicalIF":2.1,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144772323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-30DOI: 10.1016/j.dsr.2025.104560
Ankur Saini , Santosh Gaikwad , Sabyasachi Sautya , M.A. Sarun Lal , V.B. Subin Raj , N.R. Ramesh , R. Ramesh , S. Ramesh , G.A. Ramadass
The deep-sea harbors a diverse array of organisms playing crucial roles in the ecosystem yet remains largely unexplored. Enteropneusta, commonly known as acorn worms, are a key component of the deep-sea benthos as they play a major role in surficial bioturbation and nutrient cycling. However, knowledge about their distribution, abundance, and behavior in these profound depths is scarce. This study provides the first quantitative assessment of enteropneusta (acorn worms) in the Central Indian Ocean Basin at depths greater than 5200 m. The data were collected using high-resolution seafloor imagery captured by an Autonomous Underwater Vehicle (AUV), which is pre-programmed to carry out surveys independently—unlike Remotely Operated Vehicles (ROVs), which require continuous control by operators aboard the surface vessel. In this study the AUV analyzed an area of 0.5 km2, revealing 2955 enteropneust fecal trails and 13 acorn worms (12 Tergivelum sp. and single Allapasus sp.). The study examined trail characteristics, including shapes, area coverage, and quality, as well as acorn worm morphology. Spiral trails dominated, with no significant preference for rotational direction. Trail quality was ranked from 1° to 3°, with most trails being 2° and 3° quality. This pioneering work provides crucial insights into deep-sea ecosystem functioning in the region, informing responsible decision-making regarding potential PMN exploration activities. This report also a first kind of its quantitative approach of enteropneusta among all the potential PMN sites in the global ocean. The findings contribute to our understanding of deep-sea biodiversity and ecological dynamics in the Indian Ocean.
{"title":"First quantitative assessment of deep-sea acorn worm (Enteropneusta) in PMN-rich zones of the Central Indian Ocean Basin","authors":"Ankur Saini , Santosh Gaikwad , Sabyasachi Sautya , M.A. Sarun Lal , V.B. Subin Raj , N.R. Ramesh , R. Ramesh , S. Ramesh , G.A. Ramadass","doi":"10.1016/j.dsr.2025.104560","DOIUrl":"10.1016/j.dsr.2025.104560","url":null,"abstract":"<div><div>The deep-sea harbors a diverse array of organisms playing crucial roles in the ecosystem yet remains largely unexplored. Enteropneusta, commonly known as acorn worms, are a key component of the deep-sea benthos as they play a major role in surficial bioturbation and nutrient cycling. However, knowledge about their distribution, abundance, and behavior in these profound depths is scarce. This study provides the first quantitative assessment of enteropneusta (acorn worms) in the Central Indian Ocean Basin at depths greater than 5200 m. The data were collected using high-resolution seafloor imagery captured by an Autonomous Underwater Vehicle (AUV), which is pre-programmed to carry out surveys independently—unlike Remotely Operated Vehicles (ROVs), which require continuous control by operators aboard the surface vessel. In this study the AUV analyzed an area of 0.5 km<sup>2</sup>, revealing 2955 enteropneust fecal trails and 13 acorn worms (12 <em>Tergivelum</em> sp. and single <em>Allapasus</em> sp.). The study examined trail characteristics, including shapes, area coverage, and quality, as well as acorn worm morphology. Spiral trails dominated, with no significant preference for rotational direction. Trail quality was ranked from 1° to 3°, with most trails being 2° and 3° quality. This pioneering work provides crucial insights into deep-sea ecosystem functioning in the region, informing responsible decision-making regarding potential PMN exploration activities. This report also a first kind of its quantitative approach of enteropneusta among all the potential PMN sites in the global ocean. The findings contribute to our understanding of deep-sea biodiversity and ecological dynamics in the Indian Ocean.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104560"},"PeriodicalIF":2.1,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-24DOI: 10.1016/j.dsr.2025.104559
Elis Brandão Rocha , Eunice da Costa Machado , Maurício Garcia de Camargo , Carlos Eduardo de Rezende , Pedro Vianna Gatts , Carlos Rafael Borges Mendes , Raul Rodrigo Costa , Mônica Wallner-Kersanach , Mauricio M. Mata , Rodrigo Kerr
The biogeochemical composition and spatial distribution of suspended particulate organic carbon (POC), its stable carbon isotope (δ13C-POC), and suspended total particulate nitrogen (PN) were investigated during the austral summer of 2020 in the Gerlache Strait, a productive coastal area of the Northern Antarctic Peninsula. This study addressed the distribution patterns relative to sea ice meltwater inputs, phytoplankton community composition, and water masses distribution, aiming to identify the primary drivers of particle composition and δ13C-POC signatures in the water column. The results showed that distinct physical-biological processes influenced the biogeochemical dynamics of POC, PN and δ13C-POC across the surface and mesopelagic layers (100–800 m) in the Gerlache Strait. Surface suspended particles indicated an autotrophic production and has been accumulated due the seasonal organic matter production and shallow stratification (<20 m). Higher surface concentrations of POC (>10 μmol L−1), PN (>2 μmol L−1) and chlorophyll-a (>2 mg m−3) were found at low salinity conditions emphasising the role of meltwater input on organic matter production. Additionally, our findings suggested the influence of phytoplankton community composition on shaping surface δ13C-POC signatures and POC/PN ratios, consistent with differences in cell size and geometry. At the mesopelagic layer, particle composition variations were associated with the distribution of the water masses in the studied region. Intrusions of old modified-Circumpolar Deep Water contributed to increase the δ13C-POC and POC/PN ratios, due to preferential remineralisation of the lighter carbon isotope (12C) and nitrogen. Conversely, High Salinity Shelf Water – a water mass recently ventilated and advected from the Weddell Sea continental shelf to the northeast sector of the Gerlache Strait – showed a particle chemical composition like that observed in the surface waters.
{"title":"Distribution, composition, and drivers of suspended particulate organic matter in the Gerlache Strait, Northern Antarctic Peninsula","authors":"Elis Brandão Rocha , Eunice da Costa Machado , Maurício Garcia de Camargo , Carlos Eduardo de Rezende , Pedro Vianna Gatts , Carlos Rafael Borges Mendes , Raul Rodrigo Costa , Mônica Wallner-Kersanach , Mauricio M. Mata , Rodrigo Kerr","doi":"10.1016/j.dsr.2025.104559","DOIUrl":"10.1016/j.dsr.2025.104559","url":null,"abstract":"<div><div>The biogeochemical composition and spatial distribution of suspended particulate organic carbon (POC), its stable carbon isotope (δ<sup>13</sup>C-POC), and suspended total particulate nitrogen (PN) were investigated during the austral summer of 2020 in the Gerlache Strait, a productive coastal area of the Northern Antarctic Peninsula. This study addressed the distribution patterns relative to sea ice meltwater inputs, phytoplankton community composition, and water masses distribution, aiming to identify the primary drivers of particle composition and δ<sup>13</sup>C-POC signatures in the water column. The results showed that distinct physical-biological processes influenced the biogeochemical dynamics of POC, PN and δ<sup>13</sup>C-POC across the surface and mesopelagic layers (100–800 m) in the Gerlache Strait. Surface suspended particles indicated an autotrophic production and has been accumulated due the seasonal organic matter production and shallow stratification (<20 m). Higher surface concentrations of POC (>10 μmol L<sup>−1</sup>), PN (>2 μmol L<sup>−1</sup>) and chlorophyll-<em>a</em> (>2 mg m<sup>−3</sup>) were found at low salinity conditions emphasising the role of meltwater input on organic matter production. Additionally, our findings suggested the influence of phytoplankton community composition on shaping surface δ<sup>13</sup>C-POC signatures and POC/PN ratios, consistent with differences in cell size and geometry. At the mesopelagic layer, particle composition variations were associated with the distribution of the water masses in the studied region. Intrusions of old modified-Circumpolar Deep Water contributed to increase the δ<sup>13</sup>C-POC and POC/PN ratios, due to preferential remineralisation of the lighter carbon isotope (<sup>12</sup>C) and nitrogen. Conversely, High Salinity Shelf Water – a water mass recently ventilated and advected from the Weddell Sea continental shelf to the northeast sector of the Gerlache Strait – showed a particle chemical composition like that observed in the surface waters.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104559"},"PeriodicalIF":2.1,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144772321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-24DOI: 10.1016/j.dsr.2025.104556
Hua Pan , Jing-Chun Feng , Bin Wang , Yue Zhang , Hui Zhang , Yan Xie , Zhi-feng Yang , Si Zhang
Elucidating the developmental processes of cold-seep carbonates is essential for understanding the evolutionary dynamics of methane cycling in cold-seep ecosystems. Cold-seep carbonates, as products of anaerobic methane oxidation, play an important role in regulating the oceanic carbon cycle. However, the mechanisms driving carbonate precipitation remain poorly understood. This study employs X-ray computed tomography to visualize bicarbonate ion concentration and sedimentary layer dynamics at pore scales (μm) in a deep-sea cold-seep environment. The results reveal that carbonate precipitation, driven by fluid supersaturation, is preferentially promoted at the sand column base by slower flow and solute accumulation, thereby generating spatial heterogeneity. Specifically, the optimal precipitation rate of 1.36 mm3/min occurs under conditions of the 420−600 μm medium-particle system and 0.06 mol/L bicarbonate concentration. The precipitation process follows a localized clogging mechanism, which in turn reduces hydraulic conductivity nonlinearly relative to porosity. Furthermore, differences in fluid mobility induce reconfigurations in fluid flow networks, ultimately prompting lateral migration and the formation of novel flow patterns. These findings provide crucial insights into carbonate formation mechanisms of, carbonate kinetics, and marine biological carbon sequestration processes.
{"title":"Carbonate precipitation characteristics in porous media of deep-sea cold seep environment by X-ray CT imaging","authors":"Hua Pan , Jing-Chun Feng , Bin Wang , Yue Zhang , Hui Zhang , Yan Xie , Zhi-feng Yang , Si Zhang","doi":"10.1016/j.dsr.2025.104556","DOIUrl":"10.1016/j.dsr.2025.104556","url":null,"abstract":"<div><div>Elucidating the developmental processes of cold-seep carbonates is essential for understanding the evolutionary dynamics of methane cycling in cold-seep ecosystems. Cold-seep carbonates, as products of anaerobic methane oxidation, play an important role in regulating the oceanic carbon cycle. However, the mechanisms driving carbonate precipitation remain poorly understood. This study employs X-ray computed tomography to visualize bicarbonate ion concentration and sedimentary layer dynamics at pore scales (μm) in a deep-sea cold-seep environment. The results reveal that carbonate precipitation, driven by fluid supersaturation, is preferentially promoted at the sand column base by slower flow and solute accumulation, thereby generating spatial heterogeneity. Specifically, the optimal precipitation rate of 1.36 mm<sup>3</sup>/min occurs under conditions of the 420−600 μm medium-particle system and 0.06 mol/L bicarbonate concentration. The precipitation process follows a localized clogging mechanism, which in turn reduces hydraulic conductivity nonlinearly relative to porosity. Furthermore, differences in fluid mobility induce reconfigurations in fluid flow networks, ultimately prompting lateral migration and the formation of novel flow patterns. These findings provide crucial insights into carbonate formation mechanisms of, carbonate kinetics, and marine biological carbon sequestration processes.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104556"},"PeriodicalIF":2.1,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144864446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Northern fur seals (NFS; Callorhinus ursinus) are a highly migratory otariid species that leave breeding grounds in autumn (October–November), travel south to winter foraging grounds, and return to breeding colonies in early spring (March–April). NFS migrate south to regions with sufficient food, and their movement is hypothesized to be correlated with several oceanographic features. Although southward migration patterns are well-documented, fine-scale information on northbound migration remains limited owing to extended pelagic wintering periods and associated tracking challenges. Using satellite tags, we tracked five juvenile and subadult male NFS from a primary wintering ground in the Sea of Japan to examine their movement patterns, migration pathways, and behavioral responses to oceanographic features. Migration was divided into stay and northbound transit phases based on movement patterns. Slower movements with frequent course changes dominated the stay phase, whereas faster and more directed movements characterized the northbound transit phase. Foraging behavior was concentrated in continental shelf-break regions, where bathymetric features enhance prey availability. Foraging was most frequent within water temperature ranges of 8 °C–13 °C, corresponding to the highly productive Kuroshio-Oyashio Transition Zone. In contrast, transit behavior predominated at water temperatures below 2 °C and above 13 °C, likely reflecting physiological constraints. NFS also exhibited transit behavior near anticyclonic eddy edges, suggesting they use high-velocity regions to reduce travel costs. This study provides valuable insights into the northbound migration strategies of NFS overwintering in the Sea of Japan, demonstrating how they use specific oceanographic features for efficient foraging and movement during migration.
{"title":"Northbound movement of northern fur seal (Callorhinus ursinus) and their response to the oceanographic features","authors":"Heping Li , Ryo Dobashi , Humio Mitsudera , Yoko Mitani","doi":"10.1016/j.dsr.2025.104558","DOIUrl":"10.1016/j.dsr.2025.104558","url":null,"abstract":"<div><div>Northern fur seals (NFS; <em>Callorhinus ursinus</em>) are a highly migratory otariid species that leave breeding grounds in autumn (October–November), travel south to winter foraging grounds, and return to breeding colonies in early spring (March–April). NFS migrate south to regions with sufficient food, and their movement is hypothesized to be correlated with several oceanographic features. Although southward migration patterns are well-documented, fine-scale information on northbound migration remains limited owing to extended pelagic wintering periods and associated tracking challenges. Using satellite tags, we tracked five juvenile and subadult male NFS from a primary wintering ground in the Sea of Japan to examine their movement patterns, migration pathways, and behavioral responses to oceanographic features. Migration was divided into stay and northbound transit phases based on movement patterns. Slower movements with frequent course changes dominated the stay phase, whereas faster and more directed movements characterized the northbound transit phase. Foraging behavior was concentrated in continental shelf-break regions, where bathymetric features enhance prey availability. Foraging was most frequent within water temperature ranges of 8 °C–13 °C, corresponding to the highly productive Kuroshio-Oyashio Transition Zone. In contrast, transit behavior predominated at water temperatures below 2 °C and above 13 °C, likely reflecting physiological constraints. NFS also exhibited transit behavior near anticyclonic eddy edges, suggesting they use high-velocity regions to reduce travel costs. This study provides valuable insights into the northbound migration strategies of NFS overwintering in the Sea of Japan, demonstrating how they use specific oceanographic features for efficient foraging and movement during migration.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104558"},"PeriodicalIF":2.1,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-04DOI: 10.1016/j.dsr.2025.104554
Matthew P. Quinan , William M. Berelson , Jaclyn E.P. Cetiner , Nick E. Rollins , Frank J. Pavia , Sijia Dong , Janice L. Jones , Mark A. Brzezinski , Jess F. Adkins
The cycling of silicon (Si) in marine sediments can have major impacts on global ocean nutrient dynamics and productivity. Si cycling in the sediment of the Cocos Ridge and overlying waters of the eastern equatorial Pacific was investigated using unique in situ and traditional ex situ pore water collection techniques as well as solid phase analysis, core incubation, and sediment trap collection. Si remineralization and burial fluxes show little variation between the four sites investigated, regardless of a ∼1600 m difference in water depth among stations. Dissolved Si concentrations in pore water from sediment depths >10 cm collected in situ were significantly and consistently higher than those collected ex situ implying a previously unrecognized sampling artifact associated with sediment core recovery and processing. The loss of dissolved Si in the ex situ pore waters is also associated with the fractionation of Si isotopes. In situ pore water δ30Si is lighter than ex situ pore water δ30Si at three of the four stations, though only significantly lighter at one. The preferential loss of light Si in ex situ pore waters is attributed to authigenic clay formation during core collection and transport from the cold, high pressure benthos to the ocean's surface. However, consistency between in situ and ex situ pore water Si gradients within 10 cm of the sediment water interface indicates remineralization fluxes previously determined using sediment core-derived pore waters remain accurate.
{"title":"Biogenic Si cycling along the Cocos Ridge: differences between in situ and ex situ extracted pore waters imply rapid rates of dissolved Si uptake upon core recovery","authors":"Matthew P. Quinan , William M. Berelson , Jaclyn E.P. Cetiner , Nick E. Rollins , Frank J. Pavia , Sijia Dong , Janice L. Jones , Mark A. Brzezinski , Jess F. Adkins","doi":"10.1016/j.dsr.2025.104554","DOIUrl":"10.1016/j.dsr.2025.104554","url":null,"abstract":"<div><div>The cycling of silicon (Si) in marine sediments can have major impacts on global ocean nutrient dynamics and productivity. Si cycling in the sediment of the Cocos Ridge and overlying waters of the eastern equatorial Pacific was investigated using unique <em>in situ</em> and traditional <em>ex situ</em> pore water collection techniques as well as solid phase analysis, core incubation, and sediment trap collection. Si remineralization and burial fluxes show little variation between the four sites investigated, regardless of a ∼1600 m difference in water depth among stations. Dissolved Si concentrations in pore water from sediment depths >10 cm collected <em>in situ</em> were significantly and consistently higher than those collected <em>ex situ</em> implying a previously unrecognized sampling artifact associated with sediment core recovery and processing. The loss of dissolved Si in the <em>ex situ</em> pore waters is also associated with the fractionation of Si isotopes. <em>In situ</em> pore water δ<sup>30</sup>Si is lighter than <em>ex situ</em> pore water δ<sup>30</sup>Si at three of the four stations, though only significantly lighter at one. The preferential loss of light Si in <em>ex situ</em> pore waters is attributed to authigenic clay formation during core collection and transport from the cold, high pressure benthos to the ocean's surface. However, consistency between <em>in situ</em> and <em>ex situ</em> pore water Si gradients within 10 cm of the sediment water interface indicates remineralization fluxes previously determined using sediment core-derived pore waters remain accurate.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104554"},"PeriodicalIF":2.3,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144589074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-03DOI: 10.1016/j.dsr.2025.104553
Guanglu Zhang , Yanyan Zhao , Jun Yang , Sheng Liu , Zhishun Zhang , Xiaoqiang Guo , Guangyao Cao , Lei Yang , Sanzhong Li , Li Zou
Planktonic foraminifera are one of the important carriers of the physico-chemical environments. Recent advances in in situ microanalysis techniques provide new insights into the spatial distribution and variations of trace element concentrations of individual foraminifera shells. In this study, we focus on the variations of the in situ Mg/Ca ratios of four planktonic foraminifera species, which live in the different depths, from the surface sediments of the northeastern slope of the South China Sea (SCS). Both electron microprobe mapping and LA-ICP-MS results indicate that Globigerinoides ruber exhibits periodic bands with high Mg contents and Mg/Ca ratios, which may be attributed to symbionts. In contrast, Neogloboquadrina dutertrei, Pulleniatina obliquiloculata, and Globorotalia inflata exhibit thick calcite layers with low Mg/Ca ratios, potentially associated with calcite crusts. Meanwhile, high Mg/Ca ratios may be attributed to the contaminants, especially on the shell surface. These findings demonstrate that the variations of Mg/Ca ratios in foraminifera shells are controlled not only by the surrounding seawater temperature but also by other factors.
Applying this method, we reconstructed Mg/Ca-SST in the northeastern SCS over the past ∼3000 years. The results indicate that the reconstructed SST trend aligns with the previous regional records, which validates the robustness of the method. We hope that this method can be widely applied in the future due to the efficiency, rapid processing, and high spatial resolution with minimal sample requirements.
{"title":"The in situ Mg/Ca ratios of planktonic foraminifera shells in the northeastern South China Sea: an attempt to get efficient and reliable proxies","authors":"Guanglu Zhang , Yanyan Zhao , Jun Yang , Sheng Liu , Zhishun Zhang , Xiaoqiang Guo , Guangyao Cao , Lei Yang , Sanzhong Li , Li Zou","doi":"10.1016/j.dsr.2025.104553","DOIUrl":"10.1016/j.dsr.2025.104553","url":null,"abstract":"<div><div>Planktonic foraminifera are one of the important carriers of the physico-chemical environments. Recent advances in <em>in situ</em> microanalysis techniques provide new insights into the spatial distribution and variations of trace element concentrations of individual foraminifera shells. In this study, we focus on the variations of the <em>in situ</em> Mg/Ca ratios of four planktonic foraminifera species, which live in the different depths, from the surface sediments of the northeastern slope of the South China Sea (SCS). Both electron microprobe mapping and LA-ICP-MS results indicate that <em>Globigerinoides ruber</em> exhibits periodic bands with high Mg contents and Mg/Ca ratios, which may be attributed to symbionts. In contrast, <em>Neogloboquadrina dutertrei, Pulleniatina obliquiloculata, and Globorotalia inflata</em> exhibit thick calcite layers with low Mg/Ca ratios, potentially associated with calcite crusts. Meanwhile, high Mg/Ca ratios may be attributed to the contaminants, especially on the shell surface. These findings demonstrate that the variations of Mg/Ca ratios in foraminifera shells are controlled not only by the surrounding seawater temperature but also by other factors.</div><div>Applying this method, we reconstructed Mg/Ca-SST in the northeastern SCS over the past ∼3000 years. The results indicate that the reconstructed SST trend aligns with the previous regional records, which validates the robustness of the method. We hope that this method can be widely applied in the future due to the efficiency, rapid processing, and high spatial resolution with minimal sample requirements.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104553"},"PeriodicalIF":2.3,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-03DOI: 10.1016/j.dsr.2025.104551
Javier Montenegro , Jessica Kolbusz , Yakufu Niyazi , Joan J. Soto-Angel , Aino Hosia , Allen G. Collins , Alan J. Jamieson , Dhugal J. Lindsay
The study of the trachymedusa Botrynema has a long history of research, encompassing over 120 years of exploration in the deep sea. Two distinct morphotypes are recognized within Botrynema: one with a characteristic apical knob and another without it. Both morphotypes are present in the subspecies B. brucei ellinorae, while only specimens with a knob are known for the remainder of B. brucei. Specimens with a knob have been reported across all oceans and latitudes, whereas specimens without a knob are only known from Arctic and Subarctic regions. In this study, we use historical records, molecular tools and phylogenetic analyses to challenge the widely accepted notion of a cosmopolitan distribution for B. brucei as traditionally understood. We propose a range expansion to the subtropical western Atlantic Ocean for B. brucei ellinorae based on molecular data and hypothesize the existence of a mesopelagic soft barrier in the North Atlantic region as a plausible explanation to emerging biogeographical patterns revealed in this study.
{"title":"An unexpected journey – the arctic deep-sea halicreatid trachymedusa Botrynema brucei ellinorae off Florida: a reassessment under an integrative taxonomic approach","authors":"Javier Montenegro , Jessica Kolbusz , Yakufu Niyazi , Joan J. Soto-Angel , Aino Hosia , Allen G. Collins , Alan J. Jamieson , Dhugal J. Lindsay","doi":"10.1016/j.dsr.2025.104551","DOIUrl":"10.1016/j.dsr.2025.104551","url":null,"abstract":"<div><div>The study of the trachymedusa <em>Botrynema</em> has a long history of research, encompassing over 120 years of exploration in the deep sea. Two distinct morphotypes are recognized within <em>Botrynema</em>: one with a characteristic apical knob and another without it. Both morphotypes are present in the subspecies <em>B. brucei ellinorae</em>, while only specimens with a knob are known for the remainder of <em>B. brucei</em>. Specimens with a knob have been reported across all oceans and latitudes, whereas specimens without a knob are only known from Arctic and Subarctic regions. In this study, we use historical records, molecular tools and phylogenetic analyses to challenge the widely accepted notion of a cosmopolitan distribution for <em>B. brucei</em> as traditionally understood. We propose a range expansion to the subtropical western Atlantic Ocean for <em>B. brucei ellinorae</em> based on molecular data and hypothesize the existence of a mesopelagic soft barrier in the North Atlantic region as a plausible explanation to emerging biogeographical patterns revealed in this study.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104551"},"PeriodicalIF":2.3,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144579332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-02DOI: 10.1016/j.dsr.2025.104552
Qinyi Zhang , Daidai Wu , Yanting Ling , Xuan Chen , Shengyi Mao , Jie Liu , Guangrong Jin
Seep activity has emerged as a critical area of research for understanding biotic communities and elemental cycling (e.g., carbon, sulfur and iron) in deep extreme environments. While previous studies have predominantly focused on sulfur isotopes in pyrite as a proxy for seep activity, recent advancements highlight the potential of iron isotopes as an additional indicator. However, the detailed mechanism of how sulfur and iron coupled in seep environment is still unclear and thus hamper the further constraint of seep activity by these two key elements. For this reason, the authors analyzed 25 samples from three sediment cores which are collected from seepage sites in the Taixinan Basin (core 973–4) and the Pearl River Mouth Basin (cores GG03 and Z22-3) in the Northern South China Sea. By using SEM-EDS analysis and in-situ sulfur (δ34S) and iron (δ56Fe) isotope measurements, also combining with results from previous studies, the evolution patterns of sulfur and iron in seep environments is explored. The δ34S values of pyrite in core 973–4 range from −18.79 ‰ to 27.26 ‰, indicating a closed-system seep activity. In contrast, pyrite in cores GG03 and Z22-3 exhibit significantly negative δ34S values (−49.75 ‰ to −46.29 ‰ and −53.88 ‰ to −37.11 ‰, respectively), characteristic of more open-system seep activities. Additionally, the δ56Fe values of pyrite are consistently negative across all cores (−1.39 ‰ to −0.31 ‰ in core 973–4, −1.59 ‰ to −0.24 ‰ in core GG03, and −1.10 ‰ to −0.20 ‰ in core Z22-3), suggesting the absence of a heavy iron isotope pool. By integrating these findings with previous results, this study demonstrates that the δ56Fe values of pyrite are influenced by the position of the sulfate-methane transition zone, diverse microbial reduction processes, and varying iron sources. Therefore, this study provides valuable data to decipher how coupled sulfur and iron evolving in seep environments by pyrite, enhancing the further understanding of elemental cycles in extreme settings.
{"title":"Constraining sulfur and iron cycling in seep systems: insights from authigenic pyrite signatures","authors":"Qinyi Zhang , Daidai Wu , Yanting Ling , Xuan Chen , Shengyi Mao , Jie Liu , Guangrong Jin","doi":"10.1016/j.dsr.2025.104552","DOIUrl":"10.1016/j.dsr.2025.104552","url":null,"abstract":"<div><div>Seep activity has emerged as a critical area of research for understanding biotic communities and elemental cycling (e.g., carbon, sulfur and iron) in deep extreme environments. While previous studies have predominantly focused on sulfur isotopes in pyrite as a proxy for seep activity, recent advancements highlight the potential of iron isotopes as an additional indicator. However, the detailed mechanism of how sulfur and iron coupled in seep environment is still unclear and thus hamper the further constraint of seep activity by these two key elements. For this reason, the authors analyzed 25 samples from three sediment cores which are collected from seepage sites in the Taixinan Basin (core 973–4) and the Pearl River Mouth Basin (cores GG03 and Z22-3) in the Northern South China Sea. By using SEM-EDS analysis and in-situ sulfur (δ<sup>34</sup>S) and iron (δ<sup>56</sup>Fe) isotope measurements, also combining with results from previous studies, the evolution patterns of sulfur and iron in seep environments is explored. The δ<sup>34</sup>S values of pyrite in core 973–4 range from −18.79 ‰ to 27.26 ‰, indicating a closed-system seep activity. In contrast, pyrite in cores GG03 and Z22-3 exhibit significantly negative δ<sup>34</sup>S values (−49.75 ‰ to −46.29 ‰ and −53.88 ‰ to −37.11 ‰, respectively), characteristic of more open-system seep activities. Additionally, the δ<sup>56</sup>Fe values of pyrite are consistently negative across all cores (−1.39 ‰ to −0.31 ‰ in core 973–4, −1.59 ‰ to −0.24 ‰ in core GG03, and −1.10 ‰ to −0.20 ‰ in core Z22-3), suggesting the absence of a heavy iron isotope pool. By integrating these findings with previous results, this study demonstrates that the δ<sup>56</sup>Fe values of pyrite are influenced by the position of the sulfate-methane transition zone, diverse microbial reduction processes, and varying iron sources. Therefore, this study provides valuable data to decipher how coupled sulfur and iron evolving in seep environments by pyrite, enhancing the further understanding of elemental cycles in extreme settings.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"223 ","pages":"Article 104552"},"PeriodicalIF":2.3,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144556734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-06-30DOI: 10.1016/j.dsr.2025.104549
Jamael C. Abato , Hiroshi Kajihara
A total of 80 nemertean specimens, representing 30 putative species, were obtained from the trawled material collected along the Japan Trench (JT) and southern Kuril-Kamchatka Trench (KKT) during the KH-22-8 and KH-23-5 cruises of the R/V Hakuho-maru in October 2022 and September 2023, respectively. Samples were collected from the 24 stations along these trenches at depths ranging from 2007 to 7654 m. Molecular and morphological analyses revealed nine species of Palaeonemertea (one in Carininidae, eight in Tubulanidae), seven species of Pilidiophora (six in Lineidae, one in Valenciinidae), and 14 species of Hoplonemertea (six Monostilifera, eight Polystilifera). All palaeonemerteans, six pilidiophorans, and eight hoplonemerteans represented species that are highly likely undescribed and distinct from species known in deep-sea environments globally in the last decade. Two new hadal hoplonemerteans were described in this study: Nemertovema kojimai sp. nov. in JT at 6211 m, and Profundonemertes hakuhoae gen. et sp. nov., found in JT and southern KKT at depths of 6807–7654 m. The phylogeny of the 30 species, including the two newly described, was analyzed using 16S, 18S, and 28S ribosomal RNA, cytochrome c oxidase subunit I (COI), and histone H3 genes. Nemertovema kojimai sp. nov. is closely related to Nemertovema norenburgi Chernyshev and Polyakova, 2019, while Profundonemertes hakuhoae gen. et sp. nov. was nested within Oerstediina, sister to Abyssonemertes kajiharai Chernyshev and Polyakova, 2018a, but with low support. Four previously described species were also reported for the first time in Japanese waters: Baseodiscus profundus Kajihara, Abukawa and Chernyshev, 2022b, in southern KKT; Dinonemertes cf. arctica Korotkevich, 1977 in both trenches; N. norenburgi, in southern KKT; and Phallonemertes murrayi (Brinkmann, 1912), in both trenches as well. The genus Nemertovema Chernyshev and Polyakova, 2018a was reported for the first time in JT, represented by N. kojimai sp. nov. and one additional undescribed species. This study provided the first comprehensive survey of deep-sea nemertean diversity along JT and updated our understanding of species diversity in KKT.
{"title":"Deep-sea nemerteans collected along the Japan Trench and the southern Kuril-Kamchatka Trench onboard the R/V Hakuho-maru with descriptions of two new species in Hoplonemertea","authors":"Jamael C. Abato , Hiroshi Kajihara","doi":"10.1016/j.dsr.2025.104549","DOIUrl":"10.1016/j.dsr.2025.104549","url":null,"abstract":"<div><div>A total of 80 nemertean specimens, representing 30 putative species, were obtained from the trawled material collected along the Japan Trench (JT) and southern Kuril-Kamchatka Trench (KKT) during the KH-22-8 and KH-23-5 cruises of the R/V <em>Hakuho-maru</em> in October 2022 and September 2023, respectively. Samples were collected from the 24 stations along these trenches at depths ranging from 2007 to 7654 m. Molecular and morphological analyses revealed nine species of Palaeonemertea (one in Carininidae, eight in Tubulanidae), seven species of Pilidiophora (six in Lineidae, one in Valenciinidae), and 14 species of Hoplonemertea (six Monostilifera, eight Polystilifera). All palaeonemerteans, six pilidiophorans, and eight hoplonemerteans represented species that are highly likely undescribed and distinct from species known in deep-sea environments globally in the last decade. Two new hadal hoplonemerteans were described in this study: <em>Nemertovema kojimai</em> sp. nov. in JT at 6211 m, and <em>Profundonemertes hakuhoae</em> gen. et sp. nov., found in JT and southern KKT at depths of 6807–7654 m. The phylogeny of the 30 species, including the two newly described, was analyzed using 16S, 18S, and 28S ribosomal RNA, cytochrome <em>c</em> oxidase subunit I (COI), and histone H3 genes. <em>Nemertovema kojimai</em> sp. nov. is closely related to <em>Nemertovema norenburgi</em> Chernyshev and Polyakova, 2019, while <em>Profundonemertes hakuhoae</em> gen. et sp. nov. was nested within Oerstediina, sister to <em>Abyssonemertes kajiharai</em> Chernyshev and Polyakova, 2018a, but with low support. Four previously described species were also reported for the first time in Japanese waters: <em>Baseodiscus profundus</em> Kajihara, Abukawa and Chernyshev, 2022b, in southern KKT; <em>Dinonemertes</em> cf. <em>arctica</em> Korotkevich, 1977 in both trenches; <em>N</em>. <em>norenburgi</em>, in southern KKT; and <em>Phallonemertes murrayi</em> (Brinkmann, 1912), in both trenches as well. The genus <em>Nemertovema</em> Chernyshev and Polyakova, 2018a was reported for the first time in JT, represented by <em>N</em>. <em>kojimai</em> sp. nov. and one additional undescribed species. This study provided the first comprehensive survey of deep-sea nemertean diversity along JT and updated our understanding of species diversity in KKT.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104549"},"PeriodicalIF":2.1,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144772322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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