Pub Date : 2025-08-18DOI: 10.1016/j.dsr.2025.104576
Yingyu Peng , Di Tian , Feng Zhou , Han Zhang , Shengming Yuan , Zifei Chen , Ruijie Ye
Two consecutive strong near-inertial waves (NIWs) events were observed by a subsurface mooring in the southern Bay of Bengal (BoB). The first event, directly triggered by two consecutive tropical cyclones, displayed a pronounced upward (downward) phase (energy) propagation. The second event, occurring approximately 14 days post-tropical cyclones, featured predominant downward phase propagation with a peak velocity of 11.2 cm/s at 120 m depth. Despite weak wind-generated near-inertial energy flux (WNEF) during the second event, stronger energy reflection was observed in the upper layer of an anticyclonic eddy (ACE). Analyses using rotary wavenumber and ray-tracing models revealed upward propagating energy, reduced buoyancy frequency, and enhanced vertical shear, suggesting NIW reflection within the ACE. Nonlinear internal wave interactions were identified as the mechanism behind the generation of 2f = f + f waves. In the second NIWs event, increased near-inertial energy and 2f wave formation were possibly linked to local NIWs, driven by wind stress input and the radiation of NIWs during the adjustment process induced by anticyclonic eddy instability. These results highlight the influence of ACEs on the vertical propagation of NIWs and enhance the understanding of the upper-layer mixing process in the southern BoB.
在孟加拉湾南部（BoB）的地下系泊观测到两个连续的强近惯性波（NIWs）事件。第一个事件由两个连续的热带气旋直接触发，表现出明显的上升（下降）阶段（能量）传播。第二次事件发生在热带气旋后约14天，主要是向下相传播，在120 m深度的峰值速度为11.2 cm/s。尽管在第二次事件中风力产生的近惯性能量通量（WNEF）较弱，但在反气旋涡（ACE）上层观测到较强的能量反射。利用旋转波数和射线追踪模型进行分析，发现能量向上传播，浮力频率降低，垂直切变增强，表明NIW在ACE内反射。非线性内波相互作用被认为是产生2f = f + f波的机制。在第二次NIWs事件中，近惯性能量的增加和2f波的形成可能与局地NIWs有关，这是由风应力输入和NIWs在反气旋涡不稳定性引起的调整过程中的辐射所驱动的。这些结果突出了ace对NIWs垂直传播的影响，并加深了对bobs南部高层混合过程的理解。
{"title":"Reflections of tropical cyclone-generated near-inertial internal waves within an anticyclonic eddy in the southern Bay of Bengal","authors":"Yingyu Peng , Di Tian , Feng Zhou , Han Zhang , Shengming Yuan , Zifei Chen , Ruijie Ye","doi":"10.1016/j.dsr.2025.104576","DOIUrl":"10.1016/j.dsr.2025.104576","url":null,"abstract":"<div><div>Two consecutive strong near-inertial waves (NIWs) events were observed by a subsurface mooring in the southern Bay of Bengal (BoB). The first event, directly triggered by two consecutive tropical cyclones, displayed a pronounced upward (downward) phase (energy) propagation. The second event, occurring approximately 14 days post-tropical cyclones, featured predominant downward phase propagation with a peak velocity of 11.2 cm/s at 120 m depth. Despite weak wind-generated near-inertial energy flux (WNEF) during the second event, stronger energy reflection was observed in the upper layer of an anticyclonic eddy (ACE). Analyses using rotary wavenumber and ray-tracing models revealed upward propagating energy, reduced buoyancy frequency, and enhanced vertical shear, suggesting NIW reflection within the ACE. Nonlinear internal wave interactions were identified as the mechanism behind the generation of 2f = f + f waves. In the second NIWs event, increased near-inertial energy and 2f wave formation were possibly linked to local NIWs, driven by wind stress input and the radiation of NIWs during the adjustment process induced by anticyclonic eddy instability. These results highlight the influence of ACEs on the vertical propagation of NIWs and enhance the understanding of the upper-layer mixing process in the southern BoB.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104576"},"PeriodicalIF":2.1,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144885361","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 : 2025-08-16DOI: 10.1016/j.dsr.2025.104575
Ziwen Wang , Qianqian Li , Zhenglin Li , Jixing Qin
Sound speed exhibits significant spatio-temporal variations in shallow waters, particularly in environments with internal solitary waves (ISWs). The temporal prediction of sound speed profiles (SSPs) can be transformed into the prediction of empirical orthogonal function (EOF) coefficients. However, dynamic oceanic phenomena can cause significant variations in the background field and EOFs, leading to representational errors. Studies have shown that the sound speed at the depth corresponding to the extreme point of the first EOF contains the most information, which can effectively reflect the SSP structure. To reduce the impact of the background field and EOF mismatch on SSP prediction accuracy, an indirect approach is proposed. Compared to directly predicting the EOF coefficients using a Long Short-Term Memory (LSTM) network, the indirect approach utilizes historical data to establish the relationship between the depth-fixed sound speed at a specified depth and the EOF coefficients using a back propagation (BP) network. The LSTM then predicts the depth-fixed sound speed for the test set. Finally, the EOF coefficients are obtained from the trained BP network and subsequently used to reconstruct the SSPs. A negative coupling relationship is observed between the first EOF component estimated by the indirect approach and the background field. This relationship causes the mutual cancellation of two error components, ultimately reducing the SSP prediction error. The indirect approach substantially enhances SSP prediction accuracy compared to the direct approach, reducing errors by approximately 0.9 m/s, reaching approximately 0.67 m/s. Moreover, it maintains high prediction accuracy with an error of approximately 0.57 m/s with a representative background field.
{"title":"Time series prediction of sound speed profiles in complex shallow water environment","authors":"Ziwen Wang , Qianqian Li , Zhenglin Li , Jixing Qin","doi":"10.1016/j.dsr.2025.104575","DOIUrl":"10.1016/j.dsr.2025.104575","url":null,"abstract":"<div><div>Sound speed exhibits significant spatio-temporal variations in shallow waters, particularly in environments with internal solitary waves (ISWs). The temporal prediction of sound speed profiles (SSPs) can be transformed into the prediction of empirical orthogonal function (EOF) coefficients. However, dynamic oceanic phenomena can cause significant variations in the background field and EOFs, leading to representational errors. Studies have shown that the sound speed at the depth corresponding to the extreme point of the first EOF contains the most information, which can effectively reflect the SSP structure. To reduce the impact of the background field and EOF mismatch on SSP prediction accuracy, an indirect approach is proposed. Compared to directly predicting the EOF coefficients using a Long Short-Term Memory (LSTM) network, the indirect approach utilizes historical data to establish the relationship between the depth-fixed sound speed at a specified depth and the EOF coefficients using a back propagation (BP) network. The LSTM then predicts the depth-fixed sound speed for the test set. Finally, the EOF coefficients are obtained from the trained BP network and subsequently used to reconstruct the SSPs. A negative coupling relationship is observed between the first EOF component estimated by the indirect approach and the background field. This relationship causes the mutual cancellation of two error components, ultimately reducing the SSP prediction error. The indirect approach substantially enhances SSP prediction accuracy compared to the direct approach, reducing errors by approximately 0.9 m/s, reaching approximately 0.67 m/s. Moreover, it maintains high prediction accuracy with an error of approximately 0.57 m/s with a representative background field.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104575"},"PeriodicalIF":2.1,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144895904","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 : 2025-08-08DOI: 10.1016/j.dsr.2025.104573
Audrey M. Pruski, Gilles Vétion, Franck Lartaud, Erwan Peru, Nadine Le Bris
Hydrodynamic and food supply favourable conditions in the Lacaze-Duthiers Canyon (northwestern Mediterranean Sea) have supported the establishment of deep-sea corals, with some of the highest densities recorded in the Mediterranean. However, increasing pressures on these vulnerable habitats raise critical questions about their ecological status and resilience to environmental changes, emphasising the need to understand their trophic ecology. This study provides the most detailed analysis to date of the lipid profiles and fatty acid signatures of two key framework-building cold-water corals, Madrepora oculata and Desmophyllum pertusum (syn. Lophelia pertusa), offering insights into their feeding strategies, dietary requirements, and nutritional condition.
The results reveal that lipid classes exhibit distinct fatty acid compositions based on functional roles (storage vs. structural). Fatty acid trophic markers (FATM) indicative of herbivorous calanoids, carnivorous copepods, and phytodetritus were detected in the storage lipids (waxes and triglycerides) of both species, yet no FATM was specific to either species. This indicates a mixed diet and dietary overlap between the two corals. However, the composition of storage lipids varied significantly across samples, likely reflecting (1) species-specific feeding preferences, with D. pertusum showing greater reliance on overwintering copepods, and (2) the dynamic availability of food resources within the canyon.
Phospholipids were enriched in polyunsaturated fatty acids (PUFA), suggesting that dietary inputs are of sufficiently high quality to meet the metabolic demands of cold-water corals. High levels of storage lipids, primarily long-term reserves (wax esters) enriched in PUFA and zooplankton markers, underscore the good nutritional status of cold-water corals in the Lacaze-Duthiers Canyon.
{"title":"In situ diet patterns and health status of cold-water corals in the Lacaze-Duthiers canyon (NW Mediterranean Sea): insights from fatty acid biomarkers on lipid classes","authors":"Audrey M. Pruski, Gilles Vétion, Franck Lartaud, Erwan Peru, Nadine Le Bris","doi":"10.1016/j.dsr.2025.104573","DOIUrl":"10.1016/j.dsr.2025.104573","url":null,"abstract":"<div><div>Hydrodynamic and food supply favourable conditions in the Lacaze-Duthiers Canyon (northwestern Mediterranean Sea) have supported the establishment of deep-sea corals, with some of the highest densities recorded in the Mediterranean. However, increasing pressures on these vulnerable habitats raise critical questions about their ecological status and resilience to environmental changes, emphasising the need to understand their trophic ecology. This study provides the most detailed analysis to date of the lipid profiles and fatty acid signatures of two key framework-building cold-water corals, <em>Madrepora oculata</em> and <em>Desmophyllum pertusum</em> (syn. <em>Lophelia pertusa</em>), offering insights into their feeding strategies, dietary requirements, and nutritional condition.</div><div>The results reveal that lipid classes exhibit distinct fatty acid compositions based on functional roles (storage vs. structural). Fatty acid trophic markers (FATM) indicative of herbivorous calanoids, carnivorous copepods, and phytodetritus were detected in the storage lipids (waxes and triglycerides) of both species, yet no FATM was specific to either species. This indicates a mixed diet and dietary overlap between the two corals. However, the composition of storage lipids varied significantly across samples, likely reflecting (1) species-specific feeding preferences, with <em>D. pertusum</em> showing greater reliance on overwintering copepods, and (2) the dynamic availability of food resources within the canyon.</div><div>Phospholipids were enriched in polyunsaturated fatty acids (PUFA), suggesting that dietary inputs are of sufficiently high quality to meet the metabolic demands of cold-water corals. High levels of storage lipids, primarily long-term reserves (wax esters) enriched in PUFA and zooplankton markers, underscore the good nutritional status of cold-water corals in the Lacaze-Duthiers Canyon.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104573"},"PeriodicalIF":2.1,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144860889","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 : 2025-08-07DOI: 10.1016/j.dsr.2025.104574
Liquan Luo , Haowen Dang , Zhiwei Zeng , Mingyuan Bu , Chen Li , Jianru Li , Yanli Lei , Wei Huang , Zhimin Jian
Cold-water coral (CWC) ecosystems are receiving ever-increasing attention. Here, the distribution of CWC on a single seamount off the northern continental shelf of the South China Sea (SCS) is investigated by combining video footage from manned submersible dives and high-resolution multibeam bathymetric data. An active CWC garden ecosystem, with an average density of 15.11 ± 2.25 individuals per 100 m2, is identified on the seamount. Video footage analysis enabled the classification of CWC into 10 distinct families. The spatial distribution of the CWC on the seamount is significantly influenced by bottom current intensity and substrate type. At the summit of the seamount, dead coral skeletons covering a large area are found on mud substrates. The distribution pattern of the studied CWC garden reveals the important role of the seamount's elevated structure in sustaining benthic ecosystems under high sedimentation-rate conditions. The widespread occurrence of dead scleractinians further indicates the presence of significant environmental stressors that may threaten the long-term viability of the CWC garden, underscoring the need for continued ecological research and conservation efforts on the continental slopes of the South China Sea.
{"title":"Zonation of a cold-water coral garden on the northern continental slope of the South China sea","authors":"Liquan Luo , Haowen Dang , Zhiwei Zeng , Mingyuan Bu , Chen Li , Jianru Li , Yanli Lei , Wei Huang , Zhimin Jian","doi":"10.1016/j.dsr.2025.104574","DOIUrl":"10.1016/j.dsr.2025.104574","url":null,"abstract":"<div><div>Cold-water coral (CWC) ecosystems are receiving ever-increasing attention. Here, the distribution of CWC on a single seamount off the northern continental shelf of the South China Sea (SCS) is investigated by combining video footage from manned submersible dives and high-resolution multibeam bathymetric data. An active CWC garden ecosystem, with an average density of 15.11 ± 2.25 individuals per 100 m<sup>2</sup>, is identified on the seamount. Video footage analysis enabled the classification of CWC into 10 distinct families. The spatial distribution of the CWC on the seamount is significantly influenced by bottom current intensity and substrate type. At the summit of the seamount, dead coral skeletons covering a large area are found on mud substrates. The distribution pattern of the studied CWC garden reveals the important role of the seamount's elevated structure in sustaining benthic ecosystems under high sedimentation-rate conditions. The widespread occurrence of dead scleractinians further indicates the presence of significant environmental stressors that may threaten the long-term viability of the CWC garden, underscoring the need for continued ecological research and conservation efforts on the continental slopes of the South China Sea.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104574"},"PeriodicalIF":2.1,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809968","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 : 2025-08-06DOI: 10.1016/j.dsr.2025.104572
Júlia R. Martins , Michael M. Mincarone , Arnaud Bertrand , Camila Artana , Flávia Lucena-Frédou , Ariane Koch-Larrouy , Rayssa S. Lima , Leandro N. Eduardo
Lanternfishes (Myctophidae) are among the most abundant vertebrates globally, playing critical roles in carbon transport, nutrient recycling, and trophic structuring of pelagic ecosystems. However, they remain poorly understood and are increasingly impacted by anthropogenic activities. Here we investigated how the plume of the world's largest river, the Amazon, shapes the diversity and assemblage structure of lanternfishes. To this end, we conducted an integrative characterization of the taxonomic diversity, distribution, and abundance of 2916 lanternfish specimens, representing 31 species, collected during the dry season (August–September 2021) across areas with varying levels of Amazon River plume influence. Based on a classification of relative importance, five species were classified as abundant and frequent, while the remaining species were predominantly classified as either scarce and frequent (nine species) or scarce and rare (17 species). In regard to vertical distribution, at least 20 of the 31 species were detected at night in epipelagic waters (0–200 m), displaying four distinct broad patterns of vertical migration and distribution. We showed that, while the Amazon Plume appears to influence lanternfish species richness and size distribution, depth is the primary variable explaining the structuring of lanternfish assemblages. Moreover, while diversity appears to be similar to other tropical regions of the Atlantic Ocean, there is a noticeable dominance of certain species, suggesting that the hydrographic structure and nutrient input from the Amazon River may favour specific species.
{"title":"Influence of the Amazon River plume on the biodiversity and assemblage structure of lanternfishes (Myctophidae)","authors":"Júlia R. Martins , Michael M. Mincarone , Arnaud Bertrand , Camila Artana , Flávia Lucena-Frédou , Ariane Koch-Larrouy , Rayssa S. Lima , Leandro N. Eduardo","doi":"10.1016/j.dsr.2025.104572","DOIUrl":"10.1016/j.dsr.2025.104572","url":null,"abstract":"<div><div>Lanternfishes (Myctophidae) are among the most abundant vertebrates globally, playing critical roles in carbon transport, nutrient recycling, and trophic structuring of pelagic ecosystems. However, they remain poorly understood and are increasingly impacted by anthropogenic activities. Here we investigated how the plume of the world's largest river, the Amazon, shapes the diversity and assemblage structure of lanternfishes. To this end, we conducted an integrative characterization of the taxonomic diversity, distribution, and abundance of 2916 lanternfish specimens, representing 31 species, collected during the dry season (August–September 2021) across areas with varying levels of Amazon River plume influence. Based on a classification of relative importance, five species were classified as abundant and frequent, while the remaining species were predominantly classified as either scarce and frequent (nine species) or scarce and rare (17 species). In regard to vertical distribution, at least 20 of the 31 species were detected at night in epipelagic waters (0–200 m), displaying four distinct broad patterns of vertical migration and distribution. We showed that, while the Amazon Plume appears to influence lanternfish species richness and size distribution, depth is the primary variable explaining the structuring of lanternfish assemblages. Moreover, while diversity appears to be similar to other tropical regions of the Atlantic Ocean, there is a noticeable dominance of certain species, suggesting that the hydrographic structure and nutrient input from the Amazon River may favour specific species.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104572"},"PeriodicalIF":2.1,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893667","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 : 2025-08-05DOI: 10.1016/j.dsr.2025.104571
Chenyu Fan , Zhuangcai Tian , Kai Cui , Jinjian Huang , Sicheng Bian , Liyu Yang , Taiping Zhang
The northeastern South China Sea is characterized by a complex system of submarine canyons, making the study of its sediment “source-to-sink” processes crucial for understanding regional tectonic-climate interactions. This study focuses on two areas: the Taiwan Canyon and northern Manila Trench in the northeastern South China Sea. We used X-ray diffraction to analyze clay minerals. The analysis examined surface and core sediments from seven sampling sites. We studied both composition and sources of these minerals. We quantified the contribution rates from different sources and detailed the transport pathways. The results indicate that clay minerals in the study area are predominantly composed of illite (58.9 %–70.7 %) and chlorite (22.2 %–39.6 %), while smectite (0.3 %–7.4 %) and kaolinite (0.3 %–12.2 %) are present in significantly lower abundances. Taiwan Island is the primary source of clay minerals (47.9–97.7 %), transported to the northern Manila Trench via the Penghu-Gaoping Canyon system and deep-water currents. Luzon Island contributes minimally (<7.4 %), with its materials carried by the Kuroshio Current. The Pearl River catchment serves as a secondary source (1.5–48.2 %). This study proposes that Pearl River sediments in the northern South China Sea are transported via two distinct pathways: (1) shelf sediments are transported through the Taiwan Canyon to the northern Manila Trench, while (2) slope sediments are delivered directly to both the mid-Taiwan Canyon (ZC4) and the northern Manila Trench (YF6). These results offer significant scientific insights into the “source-to-sink” sedimentary processes along the continental margin of the northeastern South China Sea.
{"title":"A new discovery of source contribution and transport mechanism of clay minerals in Taiwan Canyon-Manila Trench","authors":"Chenyu Fan , Zhuangcai Tian , Kai Cui , Jinjian Huang , Sicheng Bian , Liyu Yang , Taiping Zhang","doi":"10.1016/j.dsr.2025.104571","DOIUrl":"10.1016/j.dsr.2025.104571","url":null,"abstract":"<div><div>The northeastern South China Sea is characterized by a complex system of submarine canyons, making the study of its sediment “source-to-sink” processes crucial for understanding regional tectonic-climate interactions. This study focuses on two areas: the Taiwan Canyon and northern Manila Trench in the northeastern South China Sea. We used X-ray diffraction to analyze clay minerals. The analysis examined surface and core sediments from seven sampling sites. We studied both composition and sources of these minerals. We quantified the contribution rates from different sources and detailed the transport pathways. The results indicate that clay minerals in the study area are predominantly composed of illite (58.9 %–70.7 %) and chlorite (22.2 %–39.6 %), while smectite (0.3 %–7.4 %) and kaolinite (0.3 %–12.2 %) are present in significantly lower abundances. Taiwan Island is the primary source of clay minerals (47.9–97.7 %), transported to the northern Manila Trench via the Penghu-Gaoping Canyon system and deep-water currents. Luzon Island contributes minimally (<7.4 %), with its materials carried by the Kuroshio Current. The Pearl River catchment serves as a secondary source (1.5–48.2 %). This study proposes that Pearl River sediments in the northern South China Sea are transported via two distinct pathways: (1) shelf sediments are transported through the Taiwan Canyon to the northern Manila Trench, while (2) slope sediments are delivered directly to both the mid-Taiwan Canyon (ZC4) and the northern Manila Trench (YF6). These results offer significant scientific insights into the “source-to-sink” sedimentary processes along the continental margin of the northeastern South China Sea.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"224 ","pages":"Article 104571"},"PeriodicalIF":2.1,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827973","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 : 2025-07-31DOI: 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}
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