Pub Date : 2025-11-22DOI: 10.1016/j.pocean.2025.103628
Mitsuhide Sato , Fuminori Hashihama , Hongbin Liu
The pico- and nanophytoplankton communities in the eastern Indian Ocean during the fall–winter inter-monsoon season were analyzed using flow cytometry to clarify the environmental factors that control the horizontal and vertical distributions of phytoplankton. The average Synechococcus abundance within the surface mixed layer showed a significant positive correlation with the temperature and nitrate + nitrite (N + N) concentration. Similarly, the cell concentration of eukaryotic phytoplankton in the surface mixed layer was correlated with temperature but did not decrease with decreasing N + N availability. Instead, the proportion of potentially phagotrophic eukaryotic phytoplankton, assessed using a fluorescent probe, increased with decreasing N + N concentrations in the surface mixed layer. This suggested that nitrogen uptake from particles can compensate for the decrease in inorganic nitrogen nutrients in the mixed layer, which may help eukaryotic phytoplankton maintain their biomass in oligotrophic areas. Phagotrophy by eukaryotic phytoplankton in this area may facilitate their growth, with photosynthesis driven by high irradiance within the surface mixed layer, which is depleted of nitrogen. Inter-provincial variations in cell concentrations at the subsurface peak were smaller than those within the surface mixed layer. The cell concentration of Synechococcus at the peak was positively correlated with temperature. By contrast, the peak cell concentration of eukaryotes was positively correlated with light intensity at that depth, suggesting a potential light limitation. The lower potential phagotrophy in eukaryotic phytoplankton with depth suggested that they do not use phagotrophy to compensate for diminished photosynthetic carbon acquisition.
{"title":"Nutrient availability controls phytoplankton populations and their nutritional strategy in the eastern Indian Ocean","authors":"Mitsuhide Sato , Fuminori Hashihama , Hongbin Liu","doi":"10.1016/j.pocean.2025.103628","DOIUrl":"10.1016/j.pocean.2025.103628","url":null,"abstract":"<div><div>The pico- and nanophytoplankton communities in the eastern Indian Ocean during the fall–winter inter-monsoon season were analyzed using flow cytometry to clarify the environmental factors that control the horizontal and vertical distributions of phytoplankton. The average <em>Synechococcus</em> abundance within the surface mixed layer showed a significant positive correlation with the temperature and nitrate + nitrite (N + N) concentration. Similarly, the cell concentration of eukaryotic phytoplankton in the surface mixed layer was correlated with temperature but did not decrease with decreasing N + N availability. Instead, the proportion of potentially phagotrophic eukaryotic phytoplankton, assessed using a fluorescent probe, increased with decreasing N + N concentrations in the surface mixed layer. This suggested that nitrogen uptake from particles can compensate for the decrease in inorganic nitrogen nutrients in the mixed layer, which may help eukaryotic phytoplankton maintain their biomass in oligotrophic areas. Phagotrophy by eukaryotic phytoplankton in this area may facilitate their growth, with photosynthesis driven by high irradiance within the surface mixed layer, which is depleted of nitrogen. Inter-provincial variations in cell concentrations at the subsurface peak were smaller than those within the surface mixed layer. The cell concentration of <em>Synechococcus</em> at the peak was positively correlated with temperature. By contrast, the peak cell concentration of eukaryotes was positively correlated with light intensity at that depth, suggesting a potential light limitation. The lower potential phagotrophy in eukaryotic phytoplankton with depth suggested that they do not use phagotrophy to compensate for diminished photosynthetic carbon acquisition.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"240 ","pages":"Article 103628"},"PeriodicalIF":3.6,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575277","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 : 2025-11-20DOI: 10.1016/j.pocean.2025.103625
Zeshu Yu , Marty Kwok-Shing Wong , Jun Inoue , Yuan Lin , Itsuka Yabe , Tomihiko Higuchi , Susumu Hyodo , Sachihiko Itoh , Yuichiro Nishibe , Hajime Obata , Shin-ichi Ito
Environmental DNA (eDNA) method has been widely used worldwide for ecological surveys of fish. However, the accuracy of eDNA in deducing fish distribution, especially vertical distribution in the open ocean, is uncertain due to insufficient observation. This paper observed and studied the eDNA vertical distribution in the open ocean, focusing on two economically important small pelagic fishes, Sardinops melanostictus and Engraulis japonicus (here after sardine and anchovy respectively) in the Northwest Pacific. From the uninhabitable deep ocean layers, their eDNA was detected and we referred them as “DP-eDNA”, which suggests eDNA from pelagic fish may exist far below where they live. Higher DP-eDNA ratios were observed for sardine and anchovy when seawater temperature was lower, likely due to slower degradation. The sardine DP-eDNA ratio was higher when chlorophyll-a concentration (and turbidity) was higher, which may suggest that the fish eDNA could be attached to phytoplankton-produced particles that enhanced the eDNA sinking. Meanwhile, for anchovy, the DP-eDNA ratio was lower when dissolved oxygen concentrations were higher, which may be caused by a faster microbial-related degradation. The eDNA sinking velocity was estimated to be 39 − 255 m day−1 (sardine) and 36 − 241 m day−1 (anchovy), values comparable to the observation data in particulate organic matter (POM), although the DP-eDNA formation mechanism could be more complex than simple sinking. This study recorded the downward vertical movement of DNA in open ocean and its environmental-dependent characteristics, and our results deepen the considerations that should be taken when eDNA is used to deduce the vertical distribution of fish in the open ocean.
环境DNA （Environmental DNA, eDNA）方法在鱼类生态调查中得到了广泛的应用。然而，由于观测不足，eDNA推断鱼类分布的准确性，特别是在公海的垂直分布，是不确定的。本文以西北太平洋两种具有重要经济意义的小型中上层鱼类——沙丁鱼（Sardinops melanotictus）和日本沙丁鱼（Engraulis japonicus）为研究对象，对其在公海的垂直分布进行了观察和研究。从不适合居住的深海层中，检测到它们的eDNA，我们将它们称为“DP-eDNA”，这表明来自远洋鱼类的eDNA可能存在于它们生活的远低于它们的地方。当海水温度较低时，沙丁鱼和凤尾鱼的DP-eDNA比值较高，可能是由于降解速度较慢。当叶绿素-a浓度（和浑浊度）越高时，沙丁鱼的DP-eDNA比值越高，这可能表明鱼的eDNA可能附着在浮游植物产生的颗粒上，从而增强了eDNA的下沉。同时，对于凤尾鱼来说，溶解氧浓度越高，DP-eDNA比值越低，这可能是由于微生物相关的降解速度越快。eDNA沉降速度估计为39 ~ 255 m day−1（沙丁鱼）和36 ~ 241 m day−1（凤尾鱼），与颗粒有机质（POM）的观测数据相当，尽管DP-eDNA的形成机制可能比简单的沉降更为复杂。本研究记录了开放海洋中DNA的垂直向下运动及其环境依赖特征，我们的研究结果加深了使用eDNA推断开放海洋中鱼类垂直分布时应考虑的问题。
{"title":"Environmental DNA of small pelagic fish in the deep ocean","authors":"Zeshu Yu , Marty Kwok-Shing Wong , Jun Inoue , Yuan Lin , Itsuka Yabe , Tomihiko Higuchi , Susumu Hyodo , Sachihiko Itoh , Yuichiro Nishibe , Hajime Obata , Shin-ichi Ito","doi":"10.1016/j.pocean.2025.103625","DOIUrl":"10.1016/j.pocean.2025.103625","url":null,"abstract":"<div><div>Environmental DNA (eDNA) method has been widely used worldwide for ecological surveys of fish. However, the accuracy of eDNA in deducing fish distribution, especially vertical distribution in the open ocean, is uncertain due to insufficient observation. This paper observed and studied the eDNA vertical distribution in the open ocean, focusing on two economically important small pelagic fishes, <em>Sardinops melanostictus</em> and <em>Engraulis japonicus</em> (here after sardine and anchovy respectively) in the Northwest Pacific. From the uninhabitable deep ocean layers, their eDNA was detected and we referred them as “DP-eDNA”, which suggests eDNA from pelagic fish may exist far below where they live. Higher DP-eDNA ratios were observed for sardine and anchovy when seawater temperature was lower, likely due to slower degradation. The sardine DP-eDNA ratio was higher when chlorophyll-a concentration (and turbidity) was higher, which may suggest that the fish eDNA could be attached to phytoplankton-produced particles that enhanced the eDNA sinking. Meanwhile, for anchovy, the DP-eDNA ratio was lower when dissolved oxygen concentrations were higher, which may be caused by a faster microbial-related degradation. The eDNA sinking velocity was estimated to be 39 − 255 m day<sup>−1</sup> (sardine) and 36 − 241 m day<sup>−1</sup> (anchovy), values comparable to the observation data in particulate organic matter (POM), although the DP-eDNA formation mechanism could be more complex than simple sinking. This study recorded the downward vertical movement of DNA in open ocean and its environmental-dependent characteristics, and our results deepen the considerations that should be taken when eDNA is used to deduce the vertical distribution of fish in the open ocean.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"241 ","pages":"Article 103625"},"PeriodicalIF":3.6,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145559765","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 : 2025-11-19DOI: 10.1016/j.pocean.2025.103622
Xinyu Cao , Bangyi Tao , Chunli Liu , Libo Ai , Changpeng Li , Shiji Li , Xiaolong Li , Yize Zhang
The coastal waters in the northern Shandong Peninsula experienced a significant and persistent harmful algal bloom (HAB) event during the winter of 2021. This study aims to investigate the persistence and extent mechanisms of this large-scale HAB using the satellite-derived and reanalysis datasets, with a focus on the role of sea surface temperature (SST) fronts, known to influence nutrient accumulation and act as physical barriers that prevent the dispersion of algal blooms. The results showed the HAB in the winter of 2021 began in the coastal waters of the northern Dongying on October 27th near the Yellow River estuary and expanded southeastward, reaching the Yantai-Weihai coastal waters before subsiding by December 28. The anomalous intensification and early onset of the Yantai-Weihai Coastal Front (YWCF) played a crucial role in sustaining the HAB by creating a stable marine environment with enhanced nutrient concentrations. The HAB was first detected near the Yellow River estuary and subsequently spread along the coast, influenced by prevailing northwesterly winds, southeastward currents, and the impact of the YWCF. Our findings highlight the significant impact of the front on the development and persistence of HAB, suggesting that such oceanographic features could serve as key indicators for predicting future algal blooms in this region.
{"title":"Association of abnormal Yantai-Weihai coastal front with large-scale algal bloom in winter in the northern Shandong peninsula coastal waters","authors":"Xinyu Cao , Bangyi Tao , Chunli Liu , Libo Ai , Changpeng Li , Shiji Li , Xiaolong Li , Yize Zhang","doi":"10.1016/j.pocean.2025.103622","DOIUrl":"10.1016/j.pocean.2025.103622","url":null,"abstract":"<div><div>The coastal waters in the northern Shandong Peninsula experienced a significant and persistent harmful algal bloom (HAB) event during the winter of 2021. This study aims to investigate the persistence and extent mechanisms of this large-scale HAB using the satellite-derived and reanalysis datasets, with a focus on the role of sea surface temperature (SST) fronts, known to influence nutrient accumulation and act as physical barriers that prevent the dispersion of algal blooms. The results showed the HAB in the winter of 2021 began in the coastal waters of the northern Dongying on October 27th near the Yellow River estuary and expanded southeastward, reaching the Yantai-Weihai coastal waters before subsiding by December 28. The anomalous intensification and early onset of the Yantai-Weihai Coastal Front (YWCF) played a crucial role in sustaining the HAB by creating a stable marine environment with enhanced nutrient concentrations. The HAB was first detected near the Yellow River estuary and subsequently spread along the coast, influenced by prevailing northwesterly winds, southeastward currents, and the impact of the YWCF. Our findings highlight the significant impact of the front on the development and persistence of HAB, suggesting that such oceanographic features could serve as key indicators for predicting future algal blooms in this region.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"240 ","pages":"Article 103622"},"PeriodicalIF":3.6,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553661","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 : 2025-11-18DOI: 10.1016/j.pocean.2025.103624
E. Trudnowska , P. Balazy , M. Bagur , P. Kuklinski , J. Kaminsky , K. Balazy , M. Rodriguez , Z. Derwich , G. Lovrich
The waters of the Beagle Channel (55ºS; 66–70ºW) are supplied by the Cape Horn Current and become progressively modified as they flow eastward. We followed dynamics of particles and suspension feeders within Macrocystis pyrifera kelp forests along this passage spanning from the gradient starting at the inner, glacier-influenced area to the outermost oceanic region. This was realized by the simultaneous, short-term (4-days per location) but high temporal-resolution (minutes) measurements of physical environment, particle pools, and barnacle activity. An array of loggers to measure light, salinity, temperature, pH, oxygen, water level, and currents along with sediment traps, and two underwater cameras that recorded suspended particles and benthic activity were set to discuss the effect of kelp forests on modifying their coupling along the studied gradient. This included suppression of water flow and resulting entrapment of particles in dense forests, which subsequently led to high concentrations of accumulated material to be resuspended. The lower exchange of waters in a sheltered location resulted in stronger local impact of kelps on changing biochemistry of waters (e.g., increased pH through their photosynthesis). Study site with low density of kelps at glacier-influenced site enabled better light penetration in contrast to dense oceanic forests, which was of importance for barnacles displaying diurnal cyclicity in their feeding, with higher activity during night hours at two inner locations. Tidal cycles were also important for barnacles feeding, but the relation was time-lagged. The morphology of detritus reflected different origin of material (mineral vs. organic) along the studied horizontal gradient, but also different sources of particles (local vs. advected), governed by horizontal import/export via currents and tidal dynamics. Abrupt weather episodes, diurnal and tidal cycles were the main sources of bulk observed variability which illustrates how local processes, combined with episodic environmental variations interact to drive coastal benthic dynamics in a symphony characterized by distinct rhythms. Consequently, we highlight the importance of high-resolution observations to get better understanding of the functioning of kelp forests’ associated fauna and suspended matter, and that incorporating all sources of impactful variability, including atmospheric forcing, is required.
{"title":"The rhythms of environmental conditions, particles dynamics, and barnacle activity captured by underwater imaging in sub-Antarctic kelp forests of the Beagle Channel","authors":"E. Trudnowska , P. Balazy , M. Bagur , P. Kuklinski , J. Kaminsky , K. Balazy , M. Rodriguez , Z. Derwich , G. Lovrich","doi":"10.1016/j.pocean.2025.103624","DOIUrl":"10.1016/j.pocean.2025.103624","url":null,"abstract":"<div><div>The waters of the Beagle Channel (55ºS; 66–70ºW) are supplied by the Cape Horn Current and become progressively modified as they flow eastward. We followed dynamics of particles and suspension feeders within <em>Macrocystis pyrifera</em> kelp forests along this passage spanning from the gradient starting at the inner, glacier-influenced area to the outermost oceanic region. This was realized by the simultaneous, short-term (4-days per location) but high temporal-resolution (minutes) measurements of physical environment, particle pools, and barnacle activity. An array of loggers to measure light, salinity, temperature, pH, oxygen, water level, and currents along with sediment traps, and two underwater cameras that recorded suspended particles and benthic activity were set to discuss the effect of kelp forests on modifying their coupling along the studied gradient. This included suppression of water flow and resulting entrapment of particles in dense forests, which subsequently led to high concentrations of accumulated material to be resuspended. The lower exchange of waters in a sheltered location resulted in stronger local impact of kelps on changing biochemistry of waters (e.g., increased pH through their photosynthesis). Study site with low density of kelps at glacier-influenced site enabled better light penetration in contrast to dense oceanic forests, which was of importance for barnacles displaying diurnal cyclicity in their feeding, with higher activity during night hours at two inner locations. Tidal cycles were also important for barnacles feeding, but the relation was time-lagged. The morphology of detritus reflected different origin of material (mineral vs. organic) along the studied horizontal gradient, but also different sources of particles (local vs. advected), governed by horizontal import/export via currents and tidal dynamics. Abrupt weather episodes, diurnal and tidal cycles were the main sources of bulk observed variability which illustrates how local processes, combined with episodic environmental variations interact to drive coastal benthic dynamics in a symphony characterized by distinct rhythms. Consequently, we highlight the importance of high-resolution observations to get better understanding of the functioning of kelp forests’ associated fauna and suspended matter, and that incorporating all sources of impactful variability, including atmospheric forcing, is required.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"240 ","pages":"Article 103624"},"PeriodicalIF":3.6,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553664","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}
Internal solitary waves (ISWs) are commonly emitted in stratified flows under the action of the tidal current over rough topography. ISWs have been extensively observed far from their generation zone. However, there is a scarcity of in-situ measurements where these phenomena originate, and our comprehension of their generation heavily relies on numerical simulations. The Strait of Gibraltar is well known for large amplitude ISWs propagating eastward from Camarinal Sill – the main topographic feature – towards the Alboran Sea. Our field experiment and satellite images reveal the complex spatial structure of the bore at the Camarinal Sill, showing multiple bores. We evidence that two packets of organized ISWs effectively propagate near the generation zone, leading to different signatures at our moorings. This analysis offers a unique chance to compare synchronous in-situ data with satellite images of internal bore. Finally, the possible consequences of these multiple wave trains in the far field dynamics are discussed with a focus on the non-rank-ordered pattern observed at the eastern exit of the Strait.
{"title":"Variability of the internal solitary waves generated at Camarinal Sill in the Strait of Gibraltar","authors":"Jean-Baptiste Roustan , Lucie Bordois , Xavier Carton , Francis Auclair , Franck Dumas","doi":"10.1016/j.pocean.2025.103621","DOIUrl":"10.1016/j.pocean.2025.103621","url":null,"abstract":"<div><div>Internal solitary waves (ISWs) are commonly emitted in stratified flows under the action of the tidal current over rough topography. ISWs have been extensively observed far from their generation zone. However, there is a scarcity of in-situ measurements where these phenomena originate, and our comprehension of their generation heavily relies on numerical simulations. The Strait of Gibraltar is well known for large amplitude ISWs propagating eastward from Camarinal Sill – the main topographic feature – towards the Alboran Sea. Our field experiment and satellite images reveal the complex spatial structure of the bore at the Camarinal Sill, showing multiple bores. We evidence that two packets of organized ISWs effectively propagate near the generation zone, leading to different signatures at our moorings. This analysis offers a unique chance to compare synchronous in-situ data with satellite images of internal bore. Finally, the possible consequences of these multiple wave trains in the far field dynamics are discussed with a focus on the non-rank-ordered pattern observed at the eastern exit of the Strait.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"241 ","pages":"Article 103621"},"PeriodicalIF":3.6,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553663","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 : 2025-11-17DOI: 10.1016/j.pocean.2025.103623
Henry Knauber, Angelika Brandt, Torben Riehl
The vast extent of the deep-sea floor raises questions about the connectivity and extent of benthic biodiversity, while simultaneously rendering studies on biogeographic distribution patterns and population genetics difficult due to underexploration. This study investigates the biodiversity, connectivity and biogeography of janiroidean isopods from the relatively well-studied North Pacific (NP), a taxon often considered to mostly comprise poor dispersers. This contribution focuses on janiroidean species recorded from the NP abyssal plains interconnecting the regions surrounding the eastern Aleutian Trench (AT), the Kuril-Kamchatka Trench (KKT), and the Japan Trench (JT). It has the goal to investigate faunal connectivity and to infer potential influences of Isolation by Distance. The study is centered around the epibenthic Haploniscidae Hansen, 1916 and the endobenthic Macrostylidae Hansen, 1916, analyzing their distributional ranges as well as molecular structuring and differentiation patterns using an extensive dataset of 16S rRNA sequences and COI barcodes. Species delimitation analyses revealed the existence of multiple new “cryptic” species amongst established taxa in both families, resulting in much more diverse biodiversity patterns across the whole NP than initially assumed based on morphology alone. While only a single macrostylid species showed a distribution spanning from the abyssal plains of the AT region to the ones of the JT/KKT regions, multiple haploniscid species reportedly possess ranges of several thousand kilometers across the abyssal plains of the NP. Isolation by Distance was inferred within most species appearing in at least two of the three greater trench regions investigated. These observed differences in biogeography and the inferred molecular variation patterns can be explained by different life-history strategies.
{"title":"Traversing the North Pacific: Biogeography and connectivity patterns of deep-sea isopods across three trench systems","authors":"Henry Knauber, Angelika Brandt, Torben Riehl","doi":"10.1016/j.pocean.2025.103623","DOIUrl":"10.1016/j.pocean.2025.103623","url":null,"abstract":"<div><div>The vast extent of the deep-sea floor raises questions about the connectivity and extent of benthic biodiversity, while simultaneously rendering studies on biogeographic distribution patterns and population genetics difficult due to underexploration. This study investigates the biodiversity, connectivity and biogeography of janiroidean isopods from the relatively well-studied North Pacific (NP), a taxon often considered to mostly comprise poor dispersers. This contribution focuses on janiroidean species recorded from the NP abyssal plains interconnecting the regions surrounding the eastern Aleutian Trench (AT), the Kuril-Kamchatka Trench (KKT), and the Japan Trench (JT). It has the goal to investigate faunal connectivity and to infer potential influences of Isolation by Distance. The study is centered around the epibenthic Haploniscidae <span><span>Hansen, 1916</span></span> and the endobenthic Macrostylidae <span><span>Hansen, 1916</span></span>, analyzing their distributional ranges as well as molecular structuring and differentiation patterns using an extensive dataset of 16S rRNA sequences and COI barcodes. Species delimitation analyses revealed the existence of multiple new “cryptic” species amongst established taxa in both families, resulting in much more diverse biodiversity patterns across the whole NP than initially assumed based on morphology alone. While only a single macrostylid species showed a distribution spanning from the abyssal plains of the AT region to the ones of the JT/KKT regions, multiple haploniscid species reportedly possess ranges of several thousand kilometers across the abyssal plains of the NP. Isolation by Distance was inferred within most species appearing in at least two of the three greater trench regions investigated. These observed differences in biogeography and the inferred molecular variation patterns can be explained by different life-history strategies.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"240 ","pages":"Article 103623"},"PeriodicalIF":3.6,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145554315","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}
The AleutBio Expedition, which was conducted from July to September 2022 across the Aleutian Trench and abyssal depths of the Bering Sea, aimed at expanding the knowledge on the distribution of marine organisms in the subpolar northern Pacific Ocean. The present study analyses ostracods (Crustacea) collected during this expedition and presents the descriptions of three new, deep-sea ostracod species from the family Trachyleberididae: Abyssocythere piovesanae sp. nov., Abyssocythereis matzkekaraszae sp. nov., and Henryhowella coronispinata sp. nov. The material was collected using two types of epibenthic sledges from 10 stations at depths from 3,500 to 7,200 m. Morphological analysis was conducted via stereomicroscopy of the soft body and scanning electron microscopy of the valves. It is the first time that soft parts of Abyssocythere and Henryhowella are described. Our findings expand the known geographic distribution of these genera and offer insights into their morphological diversity, including unique ornamentation patterns, hinge structures and valve overlap. We also provide a new synonymy for the two previously described species of Abyssocythereis and a review of Abyssocythereis sulcatoperforata (Brady, 1880), based on the reanalysis of its lectotype and, we also describe the soft parts of Henryhowella for the first time. Our research contributes significantly to the understanding of ostracod diversity and adaptation in the deep sea and underlines the importance of continued exploration of these largely understudied ecosystems.
{"title":"Biogeographic range expansion of Trachyleberididae (Ostracoda, Crustacea) genera evidenced by three new species from the Aleutian Trench and Bering Sea","authors":"Rayran Araújo Praxedes , Angelika Brandt , Simone Nunes Brandão","doi":"10.1016/j.pocean.2025.103617","DOIUrl":"10.1016/j.pocean.2025.103617","url":null,"abstract":"<div><div>The AleutBio Expedition, which was conducted from July to September 2022 across the Aleutian Trench and abyssal depths of the Bering Sea, aimed at expanding the knowledge on the distribution of marine organisms in the subpolar northern Pacific Ocean. The present study analyses ostracods (Crustacea) collected during this expedition and presents the descriptions of three new, deep-sea ostracod species from the family Trachyleberididae: <em>Abyssocythere piovesanae</em> sp. nov., <em>Abyssocythereis matzkekaraszae</em> sp. nov., and <em>Henryhowella coronispinata</em> sp. nov. The material was collected using two types of epibenthic sledges from 10 stations at depths from 3,500 to 7,200 m. Morphological analysis was conducted via stereomicroscopy of the soft body and scanning electron microscopy of the valves. It is the first time that soft parts of <em>Abyssocythere</em> and <em>Henryhowella</em> are described. Our findings expand the known geographic distribution of these genera and offer insights into their morphological diversity, including unique ornamentation patterns, hinge structures and valve overlap. We also provide a new synonymy for the two previously described species of <em>Abyssocythereis</em> and a review of <em>Abyssocythereis sulcatoperforata</em> (<span><span>Brady, 1880</span></span>), based on the reanalysis of its lectotype and, we also describe the soft parts of <em>Henryhowella</em> for the first time. Our research contributes significantly to the understanding of ostracod diversity and adaptation in the deep sea and underlines the importance of continued exploration of these largely understudied ecosystems.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"240 ","pages":"Article 103617"},"PeriodicalIF":3.6,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531173","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 : 2025-11-13DOI: 10.1016/j.pocean.2025.103619
Ruth G. Curry , Michael W. Lomas , Megan R. Sullivan , Damian Grundle
Despite decades of ship-based observations at the Bermuda Atlantic Timeseries Study (BATS) site, ambiguities linger in our understanding of the region’s annual carbon cycle. Difficulties reconciling geochemical estimates of annual net community production (ANCP) with direct measurements of nutrient delivery and carbon exports (EP) have implied either an insufficient understanding of these processes, and/or that they are playing out on shorter time and spatial scales than resolved by monthly sampling. We address the latter concern using autonomous underwater gliders equipped with biogeochemical sensors to quantify ANCP from mass balances of oxygen (O2) and nitrate (NO3−) over a full annual cycle. The timing, amplitude and distributions of O2 production, consumption, and NO3− fluxes reaffirm ideas about strong seasonality in physical forcing and trophic structure creating a dual system: i.e. production fueled by NO3− supplied to the photic zone from deeper layers in the first half of the year, versus being recycled within the upper ocean during the second half. The evidence also supports recently proposed hypotheses regarding the production and recycling of carbon with non-Redfield characteristics, depleted in nitrogen and phosphorus, to explain observed patterns of high NCP in the absence of significant NO3− supply. It further identifies significant contributions to ANCP and EP potentially linked to vertically migrating communities of salps in spring after all convective activity has ceased. The improved resolution of the datasets, combined with more precise definitions of photic and subphotic integration depths, brings the estimates of ANCP and EP into better alignment with each other.
{"title":"Annual net community production and carbon exports in the central Sargasso sea from autonomous underwater glider observations","authors":"Ruth G. Curry , Michael W. Lomas , Megan R. Sullivan , Damian Grundle","doi":"10.1016/j.pocean.2025.103619","DOIUrl":"10.1016/j.pocean.2025.103619","url":null,"abstract":"<div><div>Despite decades of ship-based observations at the Bermuda Atlantic Timeseries Study (BATS) site, ambiguities linger in our understanding of the region’s annual carbon cycle. Difficulties reconciling geochemical estimates of annual net community production (ANCP) with direct measurements of nutrient delivery and carbon exports (EP) have implied either an insufficient understanding of these processes, and/or that they are playing out on shorter time and spatial scales than resolved by monthly sampling. We address the latter concern using autonomous underwater gliders equipped with biogeochemical sensors to quantify ANCP from mass balances of oxygen (O<sub>2</sub>) and nitrate (NO<sub>3</sub><sup>−</sup>) over a full annual cycle. The timing, amplitude and distributions of O<sub>2</sub> production, consumption, and NO<sub>3</sub><sup>−</sup> fluxes reaffirm ideas about strong seasonality in physical forcing and trophic structure creating a dual system: i.e. production fueled by NO<sub>3</sub><sup>−</sup> supplied to the photic zone from deeper layers in the first half of the year, versus being recycled within the upper ocean during the second half. The evidence also supports recently proposed hypotheses regarding the production and recycling of carbon with non-Redfield characteristics, depleted in nitrogen and phosphorus, to explain observed patterns of high NCP in the absence of significant NO<sub>3</sub><sup>−</sup> supply. It further identifies significant contributions to ANCP and EP potentially linked to vertically migrating communities of salps in spring after all convective activity has ceased. The improved resolution of the datasets, combined with more precise definitions of photic and subphotic integration depths, brings the estimates of ANCP and EP into better alignment with each other.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"240 ","pages":"Article 103619"},"PeriodicalIF":3.6,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531208","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 : 2025-11-13DOI: 10.1016/j.pocean.2025.103620
Rhea K. Foreman , Benedetto Barone , Eric Grabowski , Karin M. Björkman , Fernanda Henderikx-Freitas , Catherine A. Garcia , Lauren E. Manck , Angelicque E. White , Matthew J. Church , David M. Karl
In the eastern portion of the oligotrophic North Pacific Subtropical Gyre (NPSG), summertime phytoplankton blooms are recurrent events whose frequency and spatial distribution are primarily known through satellite ocean color observations. Field sampling of blooms has been sparse, so their biogeochemical structure, ecosystem dynamics, and mechanisms of initiation have not been well described, except to show that they are commonly driven by diatom-diazotroph associations (DDAs). To better understand bloom dynamics, an oceanographic expedition in the summer of 2022 targeted a large (225,000 km2), long-lived (3 months) Hemiaulus-Richelia bloom north of the Hawaiian Islands for a comprehensive and multidisciplinary investigation into the bloom’s microbial community composition, nutrient dynamics, suspended and sinking particulate matter, primary production and nitrogen (N2) fixation, and abundances of genes catalyzing N2 fixation and ammonia oxidation (nifH and amoA genes). These novel observations were interpreted together with previous bloom and non-bloom observations from Station ALOHA, the nearby field site of the Hawaii Ocean Time-series program, to gain a general understanding of bloom ecology and the biogeochemical conditions that regulate bloom initiation and demise. We found that a bloom is likely initiated from a ubiquitous summertime seed population of DDAs in the presence of (1) an above-average concentration of phosphate and silicate, (2) a shallow mixed layer that retains DDAs in high light, and (3) low mortality. The build-up of biomass in a bloom leads to a substantial increase in light attenuation; for example, in the 2022 bloom, the depth of the 1% surface light level shoaled by 50 m compared to non-bloom conditions. Decreased photon flux to the lower euphotic zone (>50 m) had significant biological and chemical consequences for the water column, including a diminished abundance of Prochlorococcus and an accumulation of ammonium due to net heterotrophic conditions. The collapse of a bloom can be caused by nutrient depletion (most likely phosphorus in our study region), a deepening mixed layer, and/or enhanced mortality (e.g., a rise in the abundance of grazers, viruses, or parasites). The average carbon export efficiency is high from DDA blooms (in large part because they are mineral-ballasted organisms), and the contribution from blooms to annual, gyre-wide export of organic matter is expected to be substantial.
{"title":"Biogeochemical anatomy and ecosystem dynamics of a large phytoplankton bloom north of the Hawaiian Islands","authors":"Rhea K. Foreman , Benedetto Barone , Eric Grabowski , Karin M. Björkman , Fernanda Henderikx-Freitas , Catherine A. Garcia , Lauren E. Manck , Angelicque E. White , Matthew J. Church , David M. Karl","doi":"10.1016/j.pocean.2025.103620","DOIUrl":"10.1016/j.pocean.2025.103620","url":null,"abstract":"<div><div>In the eastern portion of the oligotrophic North Pacific Subtropical Gyre (NPSG), summertime phytoplankton blooms are recurrent events whose frequency and spatial distribution are primarily known through satellite ocean color observations. Field sampling of blooms has been sparse, so their biogeochemical structure, ecosystem dynamics, and mechanisms of initiation have not been well described, except to show that they are commonly driven by diatom-diazotroph associations (DDAs). To better understand bloom dynamics, an oceanographic expedition in the summer of 2022 targeted a large (225,000 km<sup>2</sup>), long-lived (3 months) <em>Hemiaulus-Richelia</em> bloom north of the Hawaiian Islands for a comprehensive and multidisciplinary investigation into the bloom’s microbial community composition, nutrient dynamics, suspended and sinking particulate matter, primary production and nitrogen (N<sub>2</sub>) fixation, and abundances of genes catalyzing N<sub>2</sub> fixation and ammonia oxidation (<em>nifH</em> and <em>amoA</em> genes). These novel observations were interpreted together with previous bloom and non-bloom observations from Station ALOHA, the nearby field site of the Hawaii Ocean Time-series program, to gain a general understanding of bloom ecology and the biogeochemical conditions that regulate bloom initiation and demise. We found that a bloom is likely initiated from a ubiquitous summertime seed population of DDAs in the presence of (1) an above-average concentration of phosphate and silicate, (2) a shallow mixed layer that retains DDAs in high light, and (3) low mortality. The build-up of biomass in a bloom leads to a substantial increase in light attenuation; for example, in the 2022 bloom, the depth of the 1% surface light level shoaled by 50 m compared to non-bloom conditions. Decreased photon flux to the lower euphotic zone (>50 m) had significant biological and chemical consequences for the water column, including a diminished abundance of <em>Prochlorococcus</em> and an accumulation of ammonium due to net heterotrophic conditions. The collapse of a bloom can be caused by nutrient depletion (most likely phosphorus in our study region), a deepening mixed layer, and/or enhanced mortality (e.g., a rise in the abundance of grazers, viruses, or parasites). The average carbon export efficiency is high from DDA blooms (in large part because they are mineral-ballasted organisms), and the contribution from blooms to annual, gyre-wide export of organic matter is expected to be substantial.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"241 ","pages":"Article 103620"},"PeriodicalIF":3.6,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531172","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 : 2025-11-10DOI: 10.1016/j.pocean.2025.103618
Juan Cruz Carbajal , Jacobo Martin , Maité P. Latorre , Facundo Barrera , Julieta Kaminsky , Andreana M. Cadaillón , Martin Saraceno
The continental margin south of Tierra del Fuego and the adjacent northwest Scotia Sea serves as a transition area between the Southern Chilean and the Southern Argentinian Patagonian ecosystems. Bounded by the Northern Boundary and the Sub-Antarctic Front of the Antarctic Circumpolar Current, circulation in this area transports water and properties from the Pacific to the Atlantic Ocean, influencing the ecology of southern ecosystems. The narrow continental margin hosts a network of submarine canyons, including the deeply incised Sloggett Canyon, which intercepts and likely modifies the along-shelf-break current. Combining in-situ hydrographic measurements from a multidisciplinary cruise conducted in November 2022 with coincident global atmospheric and oceanic reanalysis, we investigate the water masses and dynamics in this understudied area. Analysis of upper ocean variability exhibited two distinct phases associated with Ekman dynamics: a relaxation phase characterized by calm wind conditions, a weak along-shelf-break current (45 cm s−1), and well-defined mesoscale activity along the Sub-Antarctic Front, and an intensification phase marked by strong wind conditions, an intense along-shelf-break current (over 80 cm s−1), and increased meander activity offshore. Despite limited field data, we document a remarkable wind-driven upwelling episode in the upper portion of the Sloggett Canyon during the intensification phase, highlighting the role of wind stress and canyon geomorphology as possible mechanisms driving upwelling events. This episode was also coincident with near-surface chlorophyll-a maxima, emphasizing the canyon’s relevance as a biological hotspot. Our findings raise new questions, highlighting the need for longer time-series studies and more dedicated multidisciplinary research efforts.
火地岛南部的大陆边缘和邻近的西北斯科舍海是智利南部和阿根廷南部巴塔哥尼亚生态系统之间的过渡区域。受南极环极流的北部边界和亚南极锋的限制，该地区的环流将水和物质从太平洋输送到大西洋，影响了南部生态系统的生态。狭窄的大陆边缘拥有海底峡谷网络，包括深切的斯洛格特峡谷，它拦截并可能改变沿大陆架断裂的水流。结合2022年11月进行的多学科巡航的现场水文测量和同步的全球大气和海洋再分析，我们研究了这一研究不足地区的水团和动力学。上层海洋变率分析显示了与Ekman动力学相关的两个不同阶段：以平静风条件为特征的松弛阶段，弱的沿大陆架断裂流（45 cm s - 1），以及沿亚南极锋明确的中尺度活动；以及以强风条件为特征的强化阶段，强的沿大陆架断裂流（超过80 cm s - 1），以及近海蜿蜒活动的增加。尽管野外资料有限，但我们在加剧阶段记录了一个显著的风驱动上升流事件，突出了风应力和峡谷地貌作为驱动上升流事件的可能机制的作用。这一事件也与近地表叶绿素a的最大值一致，强调了峡谷作为生物热点的相关性。我们的发现提出了新的问题，强调需要更长的时间序列研究和更专注的多学科研究努力。
{"title":"Circulation and wind-driven processes in the Yaganes area","authors":"Juan Cruz Carbajal , Jacobo Martin , Maité P. Latorre , Facundo Barrera , Julieta Kaminsky , Andreana M. Cadaillón , Martin Saraceno","doi":"10.1016/j.pocean.2025.103618","DOIUrl":"10.1016/j.pocean.2025.103618","url":null,"abstract":"<div><div>The continental margin south of Tierra del Fuego and the adjacent northwest Scotia Sea serves as a transition area between the Southern Chilean and the Southern Argentinian Patagonian ecosystems. Bounded by the Northern Boundary and the Sub-Antarctic Front of the Antarctic Circumpolar Current, circulation in this area transports water and properties from the Pacific to the Atlantic Ocean, influencing the ecology of southern ecosystems. The narrow continental margin hosts a network of submarine canyons, including the deeply incised Sloggett Canyon, which intercepts and likely modifies the along-shelf-break current. Combining <em>in-situ</em> hydrographic measurements from a multidisciplinary cruise conducted in November 2022 with coincident global atmospheric and oceanic reanalysis, we investigate the water masses and dynamics in this understudied area. Analysis of upper ocean variability exhibited two distinct phases associated with Ekman dynamics: a relaxation phase characterized by calm wind conditions, a weak along-shelf-break current (45 cm s<sup>−1</sup>), and well-defined mesoscale activity along the Sub-Antarctic Front, and an intensification phase marked by strong wind conditions, an intense along-shelf-break current (over 80 cm s<sup>−1</sup>), and increased meander activity offshore. Despite limited field data, we document a remarkable wind-driven upwelling episode in the upper portion of the Sloggett Canyon during the intensification phase, highlighting the role of wind stress and canyon geomorphology as possible mechanisms driving upwelling events. This episode was also coincident with near-surface chlorophyll-a maxima, emphasizing the canyon’s relevance as a biological hotspot. Our findings raise new questions, highlighting the need for longer time-series studies and more dedicated multidisciplinary research efforts.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"240 ","pages":"Article 103618"},"PeriodicalIF":3.6,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145485316","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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