Guiyan Han , Graham D. Quartly , Hui Wang , Jie Yang , Ge Chen
{"title":"Latitudinal transitions of eddy-affected zooplankton abundance in the mid-latitude North Atlantic","authors":"Guiyan Han , Graham D. Quartly , Hui Wang , Jie Yang , Ge Chen","doi":"10.1016/j.dsr.2025.104605","DOIUrl":"10.1016/j.dsr.2025.104605","url":null,"abstract":"<div><div>Mesoscale eddies play a critical role in marine ecosystems by regulating ocean environments and thereby influencing marine life. By integrating zooplankton observations from the Continuous Plankton Recorder (CPR) project with satellite-derived sea surface temperature (SST), chlorophyll (Chl) concentration, and eddy datasets based on sea surface height, we investigate the impacts of eddy populations on zooplankton community abundance in the North Atlantic. To comprehensively assess both the abundance and richness of zooplankton communities, we introduced the Abundance Index as a unifying metric. The mid-latitude North Atlantic is segmented into three latitudinal zones: the southern zone (35°N–45°N), the middle zone (45°N–55°N), and the northern zone (55°N–70°N). Our analysis revealed distinct annual variations in the Abundance Index across the three zones from 1993 to 2017. The Abundance Index was consistently higher within cyclonic eddy (CE) cores compared with anticyclonic eddy (AE) cores in the southern and northern zones, contrasting with the patterns in the middle zone. However, the composite patterns of eddy-affected Chl and SST were similar across all zones. By employing six machine learning models, we assessed the feature importance (<em>FI</em>) of log-transformed Chl (log-Chl) and SST in explaining the Abundance Index. Log-Chl was found to have a greater impact than SST, particularly in the northern zone, highlighting the greater importance of food availability relative to ambient temperature. Significant shifts in the Abundance Index differences between AE and CE cores were detected in 1998, 2002, and 2003 in the southern, middle, and northern zones, respectively, suggesting that optimal habitats may have shifted in response to ocean climate change. These findings provide deeper insights into the effects of mesoscale eddies on zooplankton communities and highlight their broader implications for marine ecosystem dynamics.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"226 ","pages":"Article 104605"},"PeriodicalIF":2.1,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145365508","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}
Kátia Cristina Cruz Capel , Pedro Leocorny , Raphael de Mello Carpes , Marcelo Visentini Kitahara , Carla Zilberberg
{"title":"High genetic connectivity of the two main cold-water scleractinian framework engineers from the Southwestern Atlantic","authors":"Kátia Cristina Cruz Capel , Pedro Leocorny , Raphael de Mello Carpes , Marcelo Visentini Kitahara , Carla Zilberberg","doi":"10.1016/j.dsr.2025.104606","DOIUrl":"10.1016/j.dsr.2025.104606","url":null,"abstract":"<div><div>Cold-water coral reefs (>150 m) are highly biodiverse ecosystems mainly engineered by few scleractinian and Porifera species. Due to the low number of framework building scleractinian species combined with their low growth rates, cold-water reefs are considered vulnerable marine ecosystems susceptible to human impacts such as demersal fisheries. Apart from their occurrence, a seminal information that subsidizes best practices for their conservation is related to gene flow/population genetics. However, research on the latter is hampered by the expensive sampling logistics and, to date, most studies have focused on the North Atlantic. Here we use microsatellite markers to understand the genetic diversity and population structure of the most important cold-water framework builders in the Southwestern Atlantic, <em>Desmophyllum pertusum</em> and <em>Solenosmilia variabilis</em>. The genotyping of 285 specimens belonging to both species showed low clonality rates, high levels of genetic diversity with no evidence of inbreeding, and no population structure along a latitudinal gradient of nearly 700 km, similar to what has been previously observed for the sympatric species <em>Madrepora oculata</em> and <em>M. piresae</em>. The recurrent absence of population structure for cold-water corals in the Southwestern Atlantic along latitudinal and depth ranges, suggests that oceanographic factors, such as the direction and speed of the Western South Atlantic Central Water and of the Antarctic Intermediate Water, combined with the spawning \"window\" and the pelagic larval duration (PLD) of these species play crucial roles in their dispersion and connectivity patterns.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"226 ","pages":"Article 104606"},"PeriodicalIF":2.1,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145365509","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}
Heidy Q. Dias , Kerstin Kröger , Andrew J. Wheeler , Riccardo Arosio , Audrey Recouvreur , Tim P. Le Bas , Isobel A. Yeo , Patrick C. Collins
{"title":"Deep-sea biotope classification using opportunistic sampling: insights for future management","authors":"Heidy Q. Dias , Kerstin Kröger , Andrew J. Wheeler , Riccardo Arosio , Audrey Recouvreur , Tim P. Le Bas , Isobel A. Yeo , Patrick C. Collins","doi":"10.1016/j.dsr.2025.104604","DOIUrl":"10.1016/j.dsr.2025.104604","url":null,"abstract":"<div><div>An iterative approach to optimise deep-sea biotope classification using a combination of acoustic data and Remotely Operated Vehicle (ROV) video footage was developed and tested at the Tropic Seamount site in the Northeast Atlantic. Two methods for biotope classification were compared: a top-down approach based on acoustic substrate classification followed by biological characterisation, and a bottom-up approach using multivariate analysis of biological assemblages only. Video transects were analysed at two spatial resolutions (200 m and 50 m segments) to assess scale effects on biotope delineation. Biotopes were classified using a combination of geological and biological data with each biotope representing a distinct combination of substrate types and their associated benthic assemblages. The bottom-up approach using 50 m segments identified 12 distinct biotopes with stronger environmental correlations compared to broader classifications at 200 m scale. This study demonstrates that shorter transects (50 m) combined with bottom-up sampling approaches are preferable for capturing the ecological heterogeneity characteristic of deep-sea seamount environments, with important implications for vulnerable marine ecosystem identification and spatial management.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104604"},"PeriodicalIF":2.1,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266257","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}
Shuduo Liu , Ben Liu , Mengran Du , Chenguang Yang , Wen Xu
{"title":"Integrated optical and acoustic monitoring of deep-sea bubble plume – A case study in Haima cold seep","authors":"Shuduo Liu , Ben Liu , Mengran Du , Chenguang Yang , Wen Xu","doi":"10.1016/j.dsr.2025.104603","DOIUrl":"10.1016/j.dsr.2025.104603","url":null,"abstract":"<div><div>Monitoring underwater bubble plumes plays a vital role in understanding the plumes’ impacts on marine ecosystems. In this study, an integrated optical and acoustic deep-sea bubble plume observation system was designed and presented. The system was deployed in the Haima cold seep at a depth of 1,386 m, where a total of 4.5 h of optical and acoustic recordings were collected. Customized methods for processing both optical and acoustic data were also developed: a convolutional neural network (CNN) was used to identify individual bubbles from optical data stream, a passive acoustic bubble detection method integrating cell averaging constant false alarm rate (CA-CFAR) detector was applied to address human-induced interferences, and parabolic interpolation was employed to improve the resolution of time delay estimation for active acoustic observation. All the collected data were comprehensively processed and analyzed. The quantitative analysis of the video data yielded a mean bubble radius of 2.35 mm, and a gas flux ranging from 0.052 L/min to 0.086 L/min. The frequency-dependent sound speed variations obtained from the active acoustic data align well with existing theory on linear pressure wave propagation in bubbly liquid, suggesting the deep-sea bubbles influence the sound speed in predictable ways. This study represents an important early development of an integrated optical and acoustic system for in-situ deep-sea bubble plume monitoring, offering valuable insights and practical considerations for future iterations of related instrumentation and data analysis algorithms.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"226 ","pages":"Article 104603"},"PeriodicalIF":2.1,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324080","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}
Martina Arcioni , Isabella D'Ambra , Salvatrice Vizzini , Danilo Scannella , Monica Calabrò , Fabio Falsone , Michele Luca Geraci , Marco Oliverio , Sergio Vitale , Germana Garofalo , Gioacchino Bono , Francesco Colloca
{"title":"Trophic ecology of the deep-sea skate Dipturus oxyrinchus (Linnaeus, 1758) in the bathyal food web of the central Mediterranean Sea","authors":"Martina Arcioni , Isabella D'Ambra , Salvatrice Vizzini , Danilo Scannella , Monica Calabrò , Fabio Falsone , Michele Luca Geraci , Marco Oliverio , Sergio Vitale , Germana Garofalo , Gioacchino Bono , Francesco Colloca","doi":"10.1016/j.dsr.2025.104602","DOIUrl":"10.1016/j.dsr.2025.104602","url":null,"abstract":"<div><div>The Mediterranean Sea is a biodiversity hotspot where most elasmobranchs are severely threatened, and there is limited knowledge regarding life history traits and trophic ecology. In this context, our study focuses on the trophic ecology of the longnose skate (<em>Dipturus oxyrinchus</em>) in the Strait of Sicily (central Mediterranean), which is designated as an Important Shark and Ray Area. The objectives of the present study were to investigate the main changes in the feeding habits of the species according to ontogeny and bathymetric distribution. We collected 152 specimens at depths between 200 and 700 m from 2016 to 2019. The combination of stomach content and stable isotope analyses allowed to classify the longnose skate as a generalist feeder, with a diet dominated by crustaceans, and smaller contributions of bony fish and cephalopods. The most consumed crustaceans were decapods (including <em>Parapenaeus longirostris, Iridonida speciosa</em>, <em>Chlorotocus crassicornis</em>) and mysids (<em>Lophogaster typicus</em>). Multivariate analyses indicated that predator total length and collection depth had a significant effect on the prey consumption patterns, which was corroborated by General Additive Models (GAM), allowing determination of the most commonly consumed prey. Significant ontogenetic changes were observed, with smaller individuals primarily preying upon benthic organisms and larger individuals adopting a more benthopelagic diet, reflected by a slight increase in trophic position. This study highlights the role of the longnose skate within the bathyal food web of the Strait of Sicily, providing useful information for ecosystem modelling, which will support effective conservation strategies.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104602"},"PeriodicalIF":2.1,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266096","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}
{"title":"Spatial variation of diapycnal mixing estimated from high-resolution seismic images of subsurface eddies, Bering Sea","authors":"Linghan Meng, Kun Zhang, Haibin Song, Shun Yang","doi":"10.1016/j.dsr.2025.104601","DOIUrl":"10.1016/j.dsr.2025.104601","url":null,"abstract":"<div><div>Turbulent mixing is a primary physical process responsible for vertical exchange of materials, heat, momentum, and energy in the ocean, and plays a key role in maintaining the overturning circulation. There are many ways to enhance ocean mixing, one of which is through oceanic eddies. However, sparse in-situ observations cannot accurately describe the structural characteristics of eddies and their contribution to turbulent mixing in the Bering Sea. In this study, we observed numerous subsurface eddies in the deep-sea region of the Bering Sea using high-resolution seismic images. These anticyclonic eddies are primarily oval-shaped or bowl-shaped, with horizontal scales of 7–65 km. The majority fall within the submesoscale range, suggesting they are mainly submesoscale eddies. They generally develop in waters shallower than 250 m, with only a few found below 300 m. Submesoscale filaments are observed on the flanks of these eddies, some of which extend downward from the eddy sides, appearing as inclined filamentous reflections. Using seismic data, we estimated diapycnal mixing and obtained its spatial distribution. The results reveal that diffusivity is significantly enhanced at the edges of eddies, especially along their sides and upper boundaries, with values reaching up to 10<sup>−3</sup> m<sup>2</sup> s<sup>−1</sup>. The enhanced diapycnal mixing may be related to submesoscale processes generated during eddy stirring and shear instability caused by eddy-induced velocities. Turbulent mixing induced by eddies promotes the vertical transport of heat, nutrients, and other substances in the ocean, thereby influencing primary productivity in the Bering Sea and significantly impacting the marine environment and ecosystem.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104601"},"PeriodicalIF":2.1,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219856","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}
{"title":"Variability of the Weddell Sea deep waters in GLORYS12v1 reanalysis","authors":"Marina Noro , Tiago S. Dotto , Marcos Tonelli , Ilana Wainer","doi":"10.1016/j.dsr.2025.104599","DOIUrl":"10.1016/j.dsr.2025.104599","url":null,"abstract":"<div><div>Understanding deep-water variability in the Weddell Sea remains a challenge, given the limited observational coverage and the difficulties ocean models face in representing fine-scale processes, particularly along the Antarctic margin. Recent high-resolution oceanic products offer a valuable opportunity to advance understanding of this region. Nevertheless, it is crucial to critically evaluate their reliability before relying on them for scientific analysis. Here, we assess the representation and variability of Warm Deep Water (WDW), Weddell Sea Deep Water (WSDW), and Weddell Sea Bottom Water (WSBW) in the 1/12° Global Ocean Physics Reanalysis (GLORYS12v1) between 1993 and 2020. GLORYS12v1 reproduces key hydrographic features and vertical stratification below 500 m, despite persistent biases in the upper ocean. WDW shows a spurious freshening trend and a cool bias in Section SR4, diverging from the observed neutral salinity and warming trend. Moreover, WSDW and WSBW exhibit overestimated warming and salinification trends. These discrepancies are primarily linked to (i) a weakening of the Weddell Gyre, which limits inflow and renewal of deep waters; (ii) stronger westerlies enhancing Ekman transport and upwelling; and (iii) changes in sea ice concentration affecting deep convection. A complex maximum covariance analysis reveals strong decadal-scale covariability between the Weddell Gyre barotropic circulation and the thermohaline structure of deep water masses, especially WSDW and WSBW. Although GLORYS12v1 resolves many relevant processes, its overestimation of trends and underrepresentation of coastal dynamics highlight the need for improved vertical coordinate schemes, refined mixing parameterizations, and enhanced observational coverage to better capture the variability of deep waters in polar regions.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104599"},"PeriodicalIF":2.1,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219855","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}
Raphael Ouillon, Carlos Muñoz-Royo, Souha El Mousadik, Thomas Peacock
{"title":"A near field study of sediment plumes for a pre-prototype nodule collector trial in the abyssal Pacific Ocean","authors":"Raphael Ouillon, Carlos Muñoz-Royo, Souha El Mousadik, Thomas Peacock","doi":"10.1016/j.dsr.2025.104595","DOIUrl":"10.1016/j.dsr.2025.104595","url":null,"abstract":"<div><div>Observations from multi-platform monitoring of the sediment plume created during a pre-prototype deep-seabed nodule mining collector trial in the Pacific Ocean are presented and discussed. A combination of fundamental and geophysical fluid dynamics theory, as well as built-for-purpose numerical modeling, is used to interpret the observations. In turn, the implications of the interpreted observations for both monitoring and modeling of deep-seabed mining sediment plumes are considered. The observations occurred over a wide range of spatial and temporal scales, obtained through collector-mounted instruments within the mining area, instrumented moorings hundreds of meters away from the mining activity, and instrumented AUV operations at distances of hundreds to thousands of meters away from the test site. At each scale, interpreting plume observations is non-trivial because of the complexity of plume dynamics. Through interpretation of the observations, we exemplify the challenge of using plume monitoring or modeling alone in order to create a complete, non-ambiguous representation of the plume that is spatio-temporally resolved. Our analysis shows that an effective strategy that encompasses monitoring technology, deployment configuration, data interpretation, modeling approach, model parametrization, and model validation must be informed by plume physics at all levels. Furthermore, non-hydrostatic physics are instrumental to the evolution of plumes, and thus plume modeling for deep-sea mining sediment plumes needs to resolve non-hydrostatic processes.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104595"},"PeriodicalIF":2.1,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145320709","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}
Kathryn E. Medina, Rosanna J. Milligan, Tracey T. Sutton, Tamara Frank
{"title":"Crustacean assemblage structure over the Charlie-Gibbs Fracture Zone of the Mid-Atlantic Ridge collected during the 2009 Henry B. Bigelow expedition","authors":"Kathryn E. Medina, Rosanna J. Milligan, Tracey T. Sutton, Tamara Frank","doi":"10.1016/j.dsr.2025.104596","DOIUrl":"10.1016/j.dsr.2025.104596","url":null,"abstract":"<div><div>The Charlie Gibbs Fracture Zone (CGFZ) consists of two nearly parallel fracture transform faults that intersect the Mid-Atlantic Ridge (MAR) axis. This area has high primary productivity and biomass levels due to the topography and water. A predominant hydrographic feature of the MAR is the Sub-Polar Front (SPF) which runs along the southern edge of the CGFZ and is known as a biogeographical boundary for multiple species. As part of The Census of Marine Life project Patterns and Processes of the Ecosystem of the northern Mid-Atlantic (MAR-ECO), the abundance and distribution patterns of the CGFZ crustacean community (primarily Decapoda) surveyed during the 2009 H B. Bigelow voyage were analyzed. Specimens were collected from five discrete depths, ranging between 0 and 3500 m deep, using a Norwegian microzooplankton trawl equipped with a multi-sampler. Analyses indicate that geographic location relative to the CGFZ is correlated to pelagic crustacean distribution, but the surrounding water masses are likely the primary drivers of abundance and diversity variations. The abundance of pelagic crustaceans was higher in the cold waters to the northwest of the CGFZ. A higher diversity was found in the warmer southeastern waters presumably due to stable influx of nutrients and food supply, and dominating mesoscale eddies located in the southeast of the study area. Benthic crustaceans in the northwest had an increased abundance and diversity compared the southeast region. This suggests that at depth, the MAR may act as a biogeographic barrier separating the two geographic regions and reducing connectivity.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104596"},"PeriodicalIF":2.1,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266256","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}
Lee C. Miller , Hilary G. Close , Kalina C. Grabb , Christine L. Huffard , Fuyan Li , David M. Karl , Kenneth L. Smith , Edward F. DeLong , Claudia R. Benitez-Nelson , Jeffrey C. Drazen , Brian N. Popp
{"title":"Transformations of particulate organic matter from the surface to the abyssal plain in the North Pacific as inferred from compound-specific stable isotope and microbial community analyses","authors":"Lee C. Miller , Hilary G. Close , Kalina C. Grabb , Christine L. Huffard , Fuyan Li , David M. Karl , Kenneth L. Smith , Edward F. DeLong , Claudia R. Benitez-Nelson , Jeffrey C. Drazen , Brian N. Popp","doi":"10.1016/j.dsr.2025.104597","DOIUrl":"10.1016/j.dsr.2025.104597","url":null,"abstract":"<div><div>Particulate organic matter (POM) produced in surface waters undergoes extensive reworking and breakdown by microbial and metazoan communities as it sinks to the abyssal seafloor and serves as the base of benthic and pelagic food webs. Here, we examined how various size classes of POM in the oligotrophic North Pacific Subtropical Gyre (Station ALOHA) and in the eutrophic California Current System (Station M) undergo microbial alteration throughout the water column. Compound-specific stable isotope analysis showed that sampling method strongly impacts the type of POM quantified as export to the deep sea. Moored abyssal sediment traps captured material that matched the isotopic composition of surface POM, indicating they collected large, fast-sinking particles, in contrast to the more heavily reworked particles collected with <em>in situ</em> filtration at the same depths. Extending δ<sup>15</sup>N analyses of amino acids to bathypelagic and abyssopelagic depths for the first time, we confirmed that most particle remineralization and reworking occurs within the upper ∼400 m of the water column regardless of initial surface productivity. At Station ALOHA, we further used 16S rRNA barcoding to characterize the microbial communities associated with the POM. We found that chemolithoautotrophic ammonia-oxidizing archaea are abundant in the upper water column at Station ALOHA and that their abundance corresponded to regions of high heterotrophic reworking as indicated by amino acid isotope analysis.</div></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"225 ","pages":"Article 104597"},"PeriodicalIF":2.1,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157709","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}