Deep-sea Research Part Ii-topical Studies in Oceanography最新文献_第2页

Optimal maternal feeding isotopic niche: influence of breeder trophic behaviour on larval growth and survival in bluefin tuna species 最佳母体摄食同位素生态位：繁殖者营养行为对蓝鳍金枪鱼幼体生长和存活的影响

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-04-01 Epub Date: 2026-02-08 DOI: 10.1016/j.dsr2.2026.105610

José M. Quintanilla , Ricardo Borrego-Santos , Estrella Malca , Isabel Riveiro , Francisco J. Abascal , Miquel Planas , Rasmus Swalethorp , Michael R. Landry , Raúl Laiz-Carrión

Maternal effects play a fundamental role in shaping early larval growth and survival in marine fishes. This study explores the relationship between maternal trophic ecology and larval growth in bluefin tunas, with a focus on Southern Bluefin Tuna (SBT) and an expanded dataset from multiple Atlantic Bluefin Tuna (ABT) populations incorporated into the General Bluefin Model (GBM). Daily growth and stable isotopes (δ¹⁵N and δ¹³C) were obtained from 80 pre-flexion SBT larvae and 355 pre-flexion larvae from the GBM dataset. Results revealed a significant negative linear trend between larval age and δ¹⁵N values, consistent with the gradual attenuation of maternally inherited isotopic signatures during development. Faster growing larvae showed significantly lower δ¹⁵N and δ¹³C values, indicating that maternal trophic behaviour and prey sources critically influence larval growth potential. Maternal isotopic niche breadth, inferred from larval isotope data, was markedly narrower in groups with optimal larval growth, suggesting that specialized (stenophagous) maternal feeding strategies promote enhanced offspring performance. These patterns were observed consistently in two bluefin species across seven different populations, despite geographic and temporal variability, highlighting a robust ecological link between maternal foraging behaviour and larval development. From these findings, we introduce the hypothesis of an Optimal Maternal Feeding Isotopic Niche, representing a constrained isotopic range associated with increased larval growth and survival. This framework advances our understanding of the influence of maternal trophic ecology on offspring fitness and offers valuable insights for the conservation and management of highly migratory pelagic species with complex reproductive strategies.

母体效应在海洋鱼类早期幼鱼的生长和生存中起着重要作用。本研究探讨了蓝鳍金枪鱼母体营养生态与幼虫生长之间的关系，重点研究了南方蓝鳍金枪鱼（SBT），并将来自多个大西洋蓝鳍金枪鱼（ABT）种群的扩展数据集纳入了通用蓝鳍金枪鱼模型（GBM）。从GBM数据集中获得80条弯曲前SBT幼虫和355条弯曲前SBT幼虫的日生长和稳定同位素（δ15N和δ13C）。结果显示，幼虫年龄与δ15N值呈显著的负线性趋势，这与发育过程中母体遗传的同位素特征逐渐衰减一致。生长较快的幼虫δ15N和δ13C值显著降低，表明母体营养行为和猎物来源对幼虫生长潜力有重要影响。根据幼虫同位素数据推断，在幼虫生长最佳的群体中，母体同位素生态位宽度明显较窄，这表明特化（窄食）母体喂养策略促进了后代性能的提高。尽管存在地理和时间上的差异，但这些模式在七个不同种群的两种蓝鳍金枪鱼中得到了一致的观察，突出了母体觅食行为与幼虫发育之间存在强大的生态联系。根据这些发现，我们提出了最佳母体喂养同位素生态位的假设，该假设代表了与幼虫生长和存活增加相关的受限同位素范围。该框架促进了我们对母体营养生态学对后代健康影响的理解，并为具有复杂繁殖策略的高洄游远洋物种的保护和管理提供了有价值的见解。

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引用次数: 0

Sinking particle export within and beneath the euphotic zone in the eastern Indian Ocean 东印度洋光带内部和下方的下沉粒子输出

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-04-01 Epub Date: 2026-01-12 DOI: 10.1016/j.dsr2.2026.105590

Michael R. Stukel , Tristan Biard , Moira Décima , Christian K. Fender , Opeyemi Kehinde , Thomas B. Kelly , Sven A. Kranz , Manon Laget , Michael R. Landry , Natalia Yingling

The eastern Indian Ocean is substantially under sampled with respect to the biological carbon pump – the suite of processes that transport the carbon fixed by phytoplankton into the deeper ocean. Using sediment traps and other ecosystem measurements, we quantified sinking organic matter flux and investigated the characteristics of sinking particles in waters overlying the Argo Abyssal Plain directly downstream of the Indonesian Throughflow off northwest Australia. Carbon export from the euphotic zone averaged 7.0 mmol C m⁻² d⁻¹, which equated to an average export efficiency (export/net primary production) of 0.19. Sinking particle flux within the euphotic zone (beneath the mixed layer, but above the deep chlorophyll maximum) averaged slightly higher than flux at the base of the euphotic zone, suggesting that the deep euphotic zone was a depth stratum of net particle remineralization. Carbon flux attenuation continued into the twilight zone with a transfer efficiency (export at euphotic depth + 100m/export at euphotic depth) of 0.62 and an average Martin's b-value of 1.1. Within the euphotic zone, fresh phytoplankton (chlorophyll associated with sinking particles, possibly contained within appendicularian houses) were an important component of sinking particles, but beneath the euphotic zone the fecal pellets of herbivorous zooplankton (phaeopigments) were more important. Changes in carbon and nitrogen isotopic composition with depth further reflected remineralization processes occurring as particles sank. We show similarities with biological carbon pump functioning in a similar semi-enclosed oligotrophic marginal sea, the Gulf of Mexico, including net remineralization across the deep chlorophyll maximum.

东印度洋的生物碳泵（将浮游植物固定的碳输送到更深的海洋的一系列过程）的采样量基本上不足。利用沉积物捕集器和其他生态系统测量方法，我们量化了澳大利亚西北部印尼通流（印度尼西亚通流）下游Argo深海平原上的下沉有机质通量，并研究了下沉颗粒的特征。从光带出口的碳平均为7.0 mmol C m−2 d−1，相当于平均出口效率（出口/净初级生产）为0.19。透光区内下沉颗粒通量（低于混合层，但高于深层叶绿素最大值）平均略高于透光区底部的通量，表明深层透光区是一个净颗粒再矿化的深层地层。碳通量衰减继续进入过渡带，转移效率（出口在光深+ 100m/出口在光深）为0.62，平均马丁b值为1.1。在泛光带内，新鲜浮游植物（与下沉颗粒相关的叶绿素，可能包含在附属虫体内）是下沉颗粒的重要组成部分，但在泛光带下，食草浮游动物的粪便颗粒（phaeopigments）更为重要。碳和氮同位素组成随深度的变化进一步反映了颗粒下沉时发生的再矿化过程。我们展示了在类似的半封闭的低营养边缘海，墨西哥湾中生物碳泵的相似之处，包括深叶绿素最大值的净再矿化。

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引用次数: 0

Time series of dissolved organic carbon in the Fram Strait (2010–2021): Indications for increased river export of DOC to the East Greenland Current? Fram海峡溶解有机碳的时间序列（2010-2021）：DOC向东格陵兰洋流输出增加的迹象？

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-04-01 Epub Date: 2025-12-22 DOI: 10.1016/j.dsr2.2025.105586

Anja Engel , Anabel von Jackowski , Vanessa Lampe , Eva-Maria Nöthig

Climate change impacts the Arctic Ocean more profoundly than other regions, with uncertain consequences for carbon cycling. Additionally, allochthonous and autochthonous sources of organic carbon undergo extreme seasonal variability. Distinguishing climate-induced changes from seasonal variability in carbon cycling thus remains a significant challenge. We investigated interannual changes in dissolved organic carbon (DOC) concentration and lability. i.e., the lifetime of DOC, which we inferred from amino acid composition, in surface waters of the Fram Strait using time series data collected between 2010 and 2021. Sampling was conducted during summer with the RV POLARSTERN at or around the Long-Term Ecological Research observatory HAUSGARTEN. Our results show that the two major water masses in Fram Strait, the Polar Water (PW; T < 0 °C; S < 34.0) predominant in the East Greenland Current and the Atlantic Water (AW; T > 3 °C; S > 34.9) predominant in the West Spitzbergen Current, differ greatly in their DOC concentration and composition. PW carries high amounts of semi-labile DOC (SL-DOC) from the Arctic Ocean southwards, whereas AW contains less but more labile DOC. No clear trend in DOC concentration over the 10-year time series was detected for AW. In contrast, samples collected in PW between 2016 and 2021 showed a 15 % increase in DOC, which was attributable to an increase in SL-DOC. Interannual variability in DOC lability was most pronounced in the eastern Fram Strait, likely driven by differences in the seasonal progression of the pelagic ecosystem. Our data suggest that DOC dynamics in the Fram Strait are influenced by an enhanced riverine input of DOC to the Arctic Ocean, leading to an increased DOC export to the North Atlantic.

气候变化对北冰洋的影响比其他地区更深远，对碳循环的影响不确定。此外，外来和本地有机碳源经历了极端的季节变化。因此，将气候引起的变化与碳循环的季节变化区分开来仍然是一项重大挑战。研究了土壤中溶解有机碳（DOC）浓度和稳定性的年际变化。即，利用2010 - 2021年的时间序列数据，从氨基酸组成推断出海峡表层DOC的寿命。夏季，利用RV POLARSTERN在HAUSGARTEN长期生态研究观测站或其周围进行采样。结果表明，以东格陵兰海流为主的极地水（PW; T < 0°C; S < 34.0）和以西斯皮次卑尔根海流为主的大西洋水（AW; T < 3°C; S > 34.9）两大海峡水团DOC浓度和组成差异较大。PW从北冰洋向南携带大量的半不稳定DOC (SL-DOC)，而AW含有较少但较多的不稳定DOC。在10年时间序列中，没有检测到AW的DOC浓度的明显趋势。相比之下，2016年至2021年期间在PW收集的样本显示DOC增加了15%，这是由于SL-DOC的增加。DOC稳定性的年际变化在海峡东部最为明显，这可能是由远洋生态系统的季节变化所驱动的。我们的数据表明，弗拉姆海峡的DOC动态受到河流向北冰洋输入DOC增强的影响，导致DOC向北大西洋输出增加。

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引用次数: 0

eDNA as a cornerstone for holistic long-term observations of Arctic marine biodiversity across trophic levels, habitats, and spatio-temporal scales eDNA作为北极海洋生物多样性在营养水平、栖息地和时空尺度上的整体长期观测的基石

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-04-01 Epub Date: 2026-01-29 DOI: 10.1016/j.dsr2.2026.105604

Katja Metfies , Christina Bienhold , Astrid Cornils , Charlotte Havermans , Henk-Jan Hoving , Alexandra Kraberg , Silke Laakmann , Véronique Merten , Barbara Niehoff , Marlis Reich , Matthias Wietz , Kasper Skytte Andersen , Magda Guadalupe Cardozo-Mino , Eduard Fadeev , Kristin Hardge , Lars Harms , Ayla Murray , Stefan Neuhaus , Eva-Maria Nöthig , Ellen Oldenburg , Antje Boetius

Embedded in the interdisciplinary design of pelagic and benthic long-term observations at the Arctic long-term ecological research site HAUSGARTEN in Fram Strait (78°36,46′N - 79°56,63′N 10°50,91′E − 5°22,24′W; 250–5500 m), environmental DNA (eDNA)-based biodiversity studies span multiple habitats and trophic levels. These studies provide valuable insights into marine ecosystem functionality and carbon fluxes, including seasonal and interannual dynamics. Since 2009, eDNA studies of pelagic eukaryotic microbial communities have regularly been conducted. Recently, these studies have been expanded to cover the biodiversity of bacteria, archaea and metazoa such as zooplankton (including gelatinous taxa) and nekton (cephalopods and fish) alongside with microbial eukaryotes. The eDNA surveys have been coupled with measurements of physical and chemical properties, such as sea-ice coverage and water masses. By applying these approaches across spatial and trophic scales in a nested approach, we characterize the dynamics in biodiversity, its role in ecological processes, with a focus on current climate change. This is achieved by considering the complexity and interconnectivity of organisms, integrating information from different disciplines across scales and habitats, and focusing on functional processes including species composition. The resulting data improve our predictive capabilities for conservation and sustainable marine management in a rapidly changing Arctic. Here, we review the design of the first interdisciplinary Arctic eDNA long-term observatory and the results of more than ten years of method development and observations.

基于环境DNA （eDNA）的生物多样性研究跨越了多个栖息地和营养水平，在位于Fram海峡（78°36,46°56 - 79°56,63'N 10°50,91'E - 5°22,24'W; 250-5500 m）的北极长期生态研究点HAUSGARTEN进行了远洋和底栖生物长期观测的跨学科设计。这些研究为海洋生态系统功能和碳通量提供了宝贵的见解，包括季节和年际动态。自2009年以来，对远洋真核微生物群落的eDNA研究已定期开展。最近，这些研究已经扩大到涵盖细菌、古细菌和后生动物的生物多样性，如浮游动物（包括胶状分类群）和浮游动物（头足类和鱼类）以及微生物真核生物。eDNA调查与物理和化学性质的测量相结合，如海冰覆盖率和水质量。通过将这些方法应用于空间和营养尺度的嵌套方法，我们描述了生物多样性的动态特征，及其在生态过程中的作用，重点关注当前的气候变化。这是通过考虑生物的复杂性和互联性，整合来自不同规模和栖息地的不同学科的信息，并关注包括物种组成在内的功能过程来实现的。由此产生的数据提高了我们在快速变化的北极地区进行保护和可持续海洋管理的预测能力。在这里，我们回顾了第一个跨学科北极eDNA长期观测站的设计以及十多年来方法开发和观测的结果。

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引用次数: 0

Differences in bloom phenology and seasonal chlorophyll-a variability in the Fram Strait's hydrographic subregions resolved by a machine learning approach 通过机器学习方法解决了弗拉姆海峡水文分区中开花物候和季节性叶绿素-a变异的差异

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-04-01 Epub Date: 2026-01-22 DOI: 10.1016/j.dsr2.2026.105603

Vanessa Lampe, Andreas Oschlies, Markus Schartau

The Fram Strait (FS) exhibits pronounced variability in chlorophyll-a (Chl-a) concentration on intra- and inter-annual scales, which is linked to the complex hydrography of the region, marked by two opposing currents separated by a frontal system. Here, we propose a machine learning approach that partitions the FS into three hydrographical subdomains (sectors) based on remotely sensed sea surface temperature, the main property for water mass identification besides salinity. The sectors resolve the cold Arctic, warm Atlantic, and intermediate front-influenced regions. This sectorisation allows for a nuanced analysis of variability, accounting for the dynamic behaviour of the currents and frontal system. Differences revealed in bloom phenology are reflected in remote-sensing Chl-a concentrations within these hydrographical sectors. Blooms (Chl-a > 1 mg m⁻³) tend to occur in May in the Arctic-influenced sector, which is subject to variable sea ice cover. They appear later, in July, in the Atlantic-influenced sector. The absolute magnitude of Chl-a variability increases with its average concentration. However, concentration-normalised, the variability is notably higher in the Arctic-influenced sector, emphasising the impact of environmental differences within the hydrographic regimes on phytoplankton dynamics. Between 2016 and 2021, we could not detect clear trends in the sectors’ average Chl-a concentration or major changes in bloom timing. This study contributes to a broader comprehension of the expected variability ranges of Chl-a in the Fram Strait. Furthermore, it provides a valuable tool for analysing large geospatial data sets, especially when in-situ measurements of the physical seawater properties are limited in spatial and temporal coverage.

弗拉姆海峡（FS）在年际和年际尺度上表现出明显的叶绿素-a （Chl-a）浓度变化，这与该地区复杂的水文地形有关，其特征是由锋面系统分隔的两股相反的洋流。在这里，我们提出了一种机器学习方法，该方法基于遥感海面温度（除了盐度之外的主要水体识别属性）将FS划分为三个水文子域（扇区）。这些扇区包括寒冷的北极、温暖的大西洋和受中间锋影响的区域。这种划分允许对变异性进行细致入微的分析，考虑到洋流和锋面系统的动态行为。开花物候的差异反映在这些水文部门的遥感Chl-a浓度上。藻华（Chl-a > 1 mg m−3）往往发生在受北极影响的地区，该地区受海冰覆盖变化的影响。它们在7月晚些时候出现在受大西洋影响的地区。Chl-a变率的绝对值随其平均浓度的增加而增加。然而，浓度标准化后，北极影响部门的变异性明显更高，强调了水文制度内环境差异对浮游植物动态的影响。在2016年至2021年期间，我们无法检测到行业平均Chl-a浓度的明确趋势或开花时间的重大变化。本研究有助于更广泛地理解海峡Chl-a的预期变率范围。此外，它为分析大型地理空间数据集提供了一个有价值的工具，特别是当对海水物理性质的现场测量在空间和时间覆盖范围有限时。

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引用次数: 0

New Zealand deep-sea black coral (Antipatharia) age and growth rates: Insights into early life growth patterns 新西兰深海黑珊瑚（Antipatharia）的年龄和生长速度：早期生命生长模式的见解

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-02-01 Epub Date: 2025-11-17 DOI: 10.1016/j.dsr2.2025.105562

Ashley N. Davis , Dianne M. Tracey , Erik Behrens , Stewart J. Fallon , John Hellstrom , Peter Marriott , Daniel J. Sinclair

Black corals (Order Antipatharia) are a diverse group found worldwide and in high abundance around Aotearoa New Zealand where their spatial distribution extends from coastal regions to the deep sea. They provide biologically important habitats and host various benthic invertebrate organisms. There is concern however, that black corals are under threat from anthropogenic activities such as mining and bottom fishing as well as from environmental changes in temperature and dissolved oxygen concentrations. Understanding the potential for black corals to recover after disturbance requires knowledge of their longevity and growth rates. Fortunately, the proteinaceous skeletons of black corals can be radiometrically dated to high precision providing age and growth data to help inform impacts. Ten black corals from two genera (Antipathella and Leiopathes) were selected from the invertebrate collection at the National Institute of Water and Atmospheric Research and radiometrically dated using radiocarbon and uranium-thorium disequilibrium (U-Th) techniques. Coral lifespans ranged from 71 years (Antipathella fiordensis) up to 2221 years (Antipatharia), and skeletons show radial growth rates ranging from 2.6 (Leiopathes sp.) – 126.7 μm/yr (A. fiordensis). High-resolution age-depth models (1.7–42.7 years/sample) were generated from U-Th age measurements leading to observations of an early life radial growth rate pattern that could provide further insights for black coral physiology. This pattern is comprised of a large growth slump after colony birth followed by a triple peak pattern which contained the maximum growth rate. These data advance our knowledge of longevity for these corals, the variability in ages and growth rates between species and regions, and their vulnerability to physical disturbances due to slow recovery rates.

黑珊瑚（Antipatharia目）是一个多样化的群体，在世界范围内都有发现，在新西兰奥特罗阿周围有大量的黑珊瑚，它们的空间分布从沿海地区延伸到深海。它们提供了重要的生物栖息地，并为各种底栖无脊椎生物提供了栖息地。然而，令人担忧的是，黑珊瑚正受到采矿和海底捕捞等人为活动以及温度和溶解氧浓度的环境变化的威胁。了解黑珊瑚在受到干扰后恢复的潜力，需要了解它们的寿命和生长速度。幸运的是，黑珊瑚的蛋白质骨骼可以通过辐射测定法精确测定年代，提供年龄和生长数据，以帮助了解影响。从美国国家水与大气研究所收集的无脊椎动物标本中（Antipathella和Leiopathes）选择了10种黑珊瑚，使用放射性碳和铀钍不平衡（U-Th）技术进行了放射性测定。珊瑚的寿命从71年（Antipathella fiordensis）到2221年（Antipatharia）不等，骨骼的径向生长速率为2.6 μm/yr (Leiopathes sp.) - 126.7 μm/yr （a.f ordensis）。通过U-Th年龄测量产生高分辨率年龄深度模型（1.7-42.7岁/样本），从而观察到早期生命径向生长速率模式，可以为黑珊瑚生理学提供进一步的见解。这种模式是由群体出生后的一个大的生长低谷，然后是一个包含最大增长率的三峰模式组成的。这些数据提高了我们对这些珊瑚寿命的认识，物种和地区之间年龄和生长速度的变化，以及由于恢复速度缓慢而对物理干扰的脆弱性。

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引用次数: 0

Spatiotemporal patterns and implications of suspended Alexandrium catenella cysts in the Pacific Arctic region 太平洋北极地区悬浮链状亚历山大菌囊的时空格局及其意义

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-02-01 Epub Date: 2025-11-19 DOI: 10.1016/j.dsr2.2025.105567

Evangeline Fachon , Robert S. Pickart , Jie Huang , Catherine Lalande , Donald M. Anderson

The persistent presence of a massive accumulation of resting cysts of the toxic dinoflagellate Alexandrium catenella on the Chukchi shelf represents a significant risk to Pacific Arctic ecosystems, as warming conditions are likely to promote harmful algal blooms of this species. While the majority of cysts are found in the benthos, cysts can also be suspended through the water column, allowing them to be transported by currents or to experience elevated temperature and light conditions that may accelerate germination. Spatial patterns of cyst suspension were investigated during a Fall 2020 survey, revealing broad presence of suspended cysts in near-bottom waters overlying benthic cyst accumulations. Enhanced suspension was observed at shallow, well-mixed stations – in some places extending beyond the bottom boundary layer into surface waters. Sinking particles collected continuously from 2017 to 2019 showed seasonal patterns of cyst flux, with export pulses during the late summer and wind-driven resuspension peaking during the fall. To evaluate the potential contribution of resuspension to bloom initiation, a hydrographic climatology of the southern Chukchi Sea was used to estimate cyst germination rates through the water column during the summer (June–September). This analysis was paired with wind-driven 1-D mixing simulations, demonstrating that cyst access to surface waters is enhanced under stormy conditions. While storm events are not currently common during the summer bloom season, a trend towards increasingly windy conditions points towards future potential for resuspended cysts to contribute to blooms in the shallow and warming waters of the Pacific Arctic region.

楚科奇大陆架上有毒的钩藻亚历山大藻（Alexandrium catenella）休眠囊的大量积累对太平洋北极生态系统构成了重大风险，因为变暖的条件可能会促进该物种的有害藻类大量繁殖。虽然大多数包囊是在底栖动物中发现的，但包囊也可以通过水柱悬浮，使它们能够通过水流运输，或者经历可能加速发芽的高温和光照条件。在2020年秋季的一项调查中，研究人员调查了囊肿悬浮物的空间模式，揭示了在底栖动物囊肿堆积的近底水域中广泛存在悬浮囊肿。在混合良好的浅站观察到悬浮增强，在一些地方，悬浮延伸到底部边界层以外的地表水。2017 - 2019年连续收集的沉降颗粒显示出囊通量的季节性模式，在夏末出现出口脉冲，在秋季达到风驱动的再悬浮峰值。利用楚科奇海南部的水文气候学资料，对夏季（6 - 9月）水柱上的包囊萌发率进行了估算。该分析与风力驱动的一维混合模拟相结合，表明在暴风雨条件下，囊肿进入地表水的机会增加。虽然目前在夏季藻华季节风暴事件并不常见，但越来越多风的趋势表明，未来可能会有重新悬浮的囊肿，导致太平洋北极地区浅水和变暖水域的藻华。

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引用次数: 0

First findings of metal-rich particles from the central Indian ocean basin: Evidence of hydrothermal mineralization 印度洋中部盆地富金属颗粒的首次发现：热液矿化的证据

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-02-01 Epub Date: 2025-11-24 DOI: 10.1016/j.dsr2.2025.105569

Ankeeta Amonkar , Sridhar D. Iyer

Metalliferous sediments are known to exist at mid-ocean ridges and near active intraplate seamounts. Here we report the occurrence of metal-rich particles of variable compositions occurring in the sediments of the Central Indian Ocean Basin (CIOB) which is an intraplate basin. These metal-rich particles have been recovered from an average water depth of 5,000m from 79°E fracture zone (pelagic clays zone) and from seamount dominated area (from siliceous sediment, and siliceous-red clay transition zone).

The metal-rich particles observed in the studied sediment samples exhibit irregular, tabular, sub-rounded shapes and have a distinct crystalline structures. They occur both as native metals and as compounds such as oxides, sulphides, and sulphates. In addition to the previously reported magnetite and aluminium spherules from the CIOB sediments, our analysis reveals a high concentration of metal-rich particles containing zinc-copper and native copper, barium sulphides, lead-barium sulphates, native lead, and silver.

The sub-surface occurrence of these metal-rich particles in the sediments indicates their derivation from recent hydrothermal activity in the basin. The fracture zone and seamounts in the vicinity could be potential sites for degassing of volatiles and formation of metalloid elements and may have co-precipitated in the sediments that bear testimony of their hydrothermal origin. To our knowledge this is the first finding of metal-rich particles from abyssal depth of nearly 5000 m in the Indian Ocean.

已知含金属沉积物存在于大洋中脊和活跃的板内海山附近。本文报道了在中印度洋盆地（CIOB）的板内盆地沉积物中出现的可变组成的富金属颗粒。这些富金属颗粒在79°E断裂带（远洋粘土带）和海山主导区（硅质沉积物和硅-红粘土过渡带）的平均水深5000 m处均有发现。在研究的沉积物样品中观察到的富金属颗粒呈不规则、板状、亚圆形，并具有明显的结晶结构。它们既以天然金属的形式存在，也以氧化物、硫化物和硫酸盐等化合物的形式存在。除了先前报道的来自CIOB沉积物的磁铁矿和铝球外，我们的分析还揭示了高浓度的富含金属的颗粒，其中含有锌铜和天然铜、硫化钡、铅硫酸钡、天然铅和银。这些富金属颗粒在沉积物中的地下赋存表明它们来源于盆地近期的热液活动。断裂带和附近的海山可能是挥发物脱气和类金属元素形成的潜在场所，并可能在沉积物中共沉淀，证明其热液起源。据我们所知，这是首次在印度洋近5000米深的深海中发现富含金属的颗粒。

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引用次数: 0

Revisiting daily growth and survival insights of Southern Bluefin Tuna (Thunnus maccoyii) larvae in the eastern Indian Ocean 重访东印度洋南部蓝鳍金枪鱼（Thunnus maccoyii）幼虫的日常生长和生存见解

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-02-01 Epub Date: 2025-12-01 DOI: 10.1016/j.dsr2.2025.105572

Ricardo Borrego-Santos , José M. Quintanilla , Raúl Laiz-Carrión , Alberto García , Estrella Malca , Francisco J. Abascal , David Die , Isabel Riveiro , Rasmus Swalethorp , Michael R. Landry

This study analyzed the growth patterns and survival of Southern bluefin tuna (SBT, Thunnus maccoyii) larvae collected during January–February 2022 in their only known spawning area in the eastern Indian Ocean (IO). Otolith microstructure was examined to characterize both population-level and intra-population growth (OPT-optimal and DEF-deficient group), with special emphasis on the flexion process, as well as to provide insights into larval survival. SBT larvae began flexion at sizes and ages comparable to those reported in other bluefin tuna species. At the intra-population level, OPT larvae reached flexion earlier in a better physical condition, with greater length, weight, and body depth, likely increasing their chances of survival at later stages. The observed larval growth rates (0.38 mm d⁻¹) exceeded that from a historical study in 1987 (0.33 mm d⁻¹), likely due to a ∼2 °C increase in sea surface temperature and shifts in prey availability. Larval survival appears to depend on a selective process based on growth, in which only a small proportion of individuals (<2 %) exhibited width increment in otoliths similar to those of surviving larvae, allowing for faster development and earlier access to larger prey. These findings highlight the need for expanded research on the early life stages of SBT, particularly in the context of ongoing ocean warming and climate change.

本研究分析了2022年1 - 2月在东印度洋唯一已知的南蓝鳍金枪鱼产卵区收集的南蓝鳍金枪鱼（SBT, Thunnus maccoyii）幼虫的生长模式和存活率。研究人员检查了耳石微观结构，以表征种群水平和种群内的生长（OPT-optimal和DEF-deficient组），特别强调了弯曲过程，并提供了对幼虫存活的见解。SBT幼虫在大小和年龄上开始弯曲，与其他蓝鳍金枪鱼物种相当。在种群内水平，OPT幼虫较早到达屈曲状态，身体状况较好，体长、体重和体深较大，可能增加其后期的生存机会。观察到的幼虫生长速率（0.38 mm d - 1）超过了1987年的历史研究（0.33 mm d - 1），可能是由于海面温度升高~ 2°C和猎物可得性的变化。幼虫的生存似乎依赖于一个基于生长的选择过程，在这个过程中，只有一小部分个体（2%）的耳石宽度增加与存活的幼虫相似，这使得它们能够更快地发育并更早地获得更大的猎物。这些发现突出表明，有必要扩大对SBT早期生命阶段的研究，特别是在持续的海洋变暖和气候变化的背景下。

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引用次数: 0

Exploring the roles of trophic mode and microbial prey size in grazing pathways of tropical oligotrophic waters of the eastern Indian ocean 探索东印度洋热带少营养水域的营养模式和微生物猎物大小在放牧路径中的作用

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2026-02-01 Epub Date: 2025-12-01 DOI: 10.1016/j.dsr2.2025.105573

Claudia Traboni , Grace F. Cawley , Karen E. Selph , Michael R. Landry , Moira Décima

Prey removal incubations were conducted in the Argo Basin (eastern Indian Ocean) to investigate the trophic ecology of the zooplankton community supporting Southern Bluefin Tuna larvae. Copepod grazing and selectivity were evaluated considering prey trophic mode and size as food quality descriptors and compared with microzooplankton grazing. Copepods ingested between 3.4 and 138 ng carbon (C) ind⁻¹ d⁻¹. Diet was dominated by mixotrophic (5–89 %) and heterotrophic (0–84 %) prey, with autotrophs contributing 2–17 %. Nanoplankton provided the highest C intake to copepods (62–99 %) versus picoplankton (0.8–38 %), despite more picoplankton cells ingested. No measurable reduction in chlorophyll a (Chla) concentration occurred from copepod grazing through food removal, suggesting an indirect trophic pathway, although gut content revealed ingestion of 0.8 μg Chla ind⁻¹ d⁻¹. Calculations from disappearance incubations imply copepod selection on picoplankton (E = 0.3) over nanoplankton, but picoplankton were likely ingested as aggregates or depressed due to a trophic cascade of copepods ingesting nano-microzooplankton. Copepods ingested protistan consumers and/or metazoans fed on ¹⁵N-cyanobacteria with ∼5-fold higher N uptake from 1 to 2 μm ¹⁵N-Synechococcus than from <1 μm ¹⁵N-Prochlorococcus. Microzooplankton grazing on eukaryotes (0.07–2.5 d⁻¹) and prokaryotes (0.3–2.1 d⁻¹) greatly exceeded copepod grazing. Microzooplankton diet consisted mostly of heterotrophs (25–59 %) and mixotrophs (13–41 %) followed by autotrophs (12–33 %), with more nano- (95–98 %) than picophytoplankton (2–5 %). Overall, microzooplankton removed most daily production (111 %) in contrast to 7 % for copepods. Our findings indicate that mixotrophy, intraguild grazing and nutrient channeling support the food web in this oligotrophic region.

为了研究南蓝鳍金枪鱼幼虫的营养生态学，在东印度洋的Argo盆地进行了捕食物去除孵化。以猎物的营养方式和大小作为食物质量描述因子，对桡足类动物的放牧和选择性进行了评价，并与微型浮游动物的放牧进行了比较。桡足类动物摄取的碳(C)在3.4 ~ 138 ng之间。食性以混合营养（5 - 89%）和异养（0 - 84%）猎物为主，自养动物占2 - 17%。纳米浮游生物为桡足类动物提供了最高的碳摄入量（62% - 99%），而微浮游生物（0.8 - 38%），尽管微浮游生物摄入的细胞更多。尽管肠道含量显示摄入了0.8 μg Chla d - 1，但桡足类动物通过食物清除并没有显著降低叶绿素a （Chla）的浓度，这表明了间接的营养途径。根据消失孵育的计算结果表明，桡足类对微浮游生物的选择（E = 0.3）高于纳米浮游生物，但微浮游生物很可能被作为聚集体摄入，或者由于桡足类摄入纳米微浮游动物的营养级联而被抑制。桡足类动物摄取的原细菌和/或后生动物以15n -蓝藻为食，从1 ~ 2 μm 15n -聚藻球菌中摄取的氮量比从1 μm 15n -原绿球藻中摄取的氮量高约5倍。浮游微动物对真核生物（0.07 ~ 2.5 d−1）和原核生物（0.3 ~ 2.1 d−1）的取食远远超过桡足类动物。微浮游动物以异养生物（25 - 59%）和混合生物（13 - 41%）为主，其次是自养生物（12 - 33%），其中纳米浮游动物（95 - 98%）多于浮游植物（2 - 5%）。总的来说，微型浮游动物减少了大部分的日产量（111%），而桡足类动物减少了7%。我们的研究结果表明，混合营养、野生放牧和营养渠道支持了这个营养不良地区的食物网。

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引用次数: 0