Deep-sea Research Part Ii-topical Studies in Oceanography最新文献

Phytoplankton community composition in the oligotrophic Argo Basin of the eastern Indian Ocean 东印度洋贫营养Argo盆地浮游植物群落组成

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.dsr2.2026.105602

Karen E. Selph , Robert H. Lampe , Natalia Yingling , Ria Bhabu , Sven A. Kranz , Andrew E. Allen , Michael R. Landry

Phytoplankton, the foundational organisms in ocean food webs, have been little studied in the Indonesian Throughflow region of the eastern Indian Ocean, the spawning area of Southern Bluefin Tuna. Here, we assess phytoplankton abundance, biomass, size structure, pigment composition, taxonomic diversity and percent functional mixotrophs of that region based on complementary approaches of flow cytometry, microscopy, taxon-specific pigments and rRNA gene sequencing. During summer (January–February) 2022, the region was characterized by warm (up to 30.5 °C), stratified, oligotrophic (nitrogen-limited) waters, with integrated euphotic zone (EZ) chlorophyll a (CHLa) of 13 mg m⁻². EZ mean CHLa was low in the upper layer (85 ng L⁻¹) and 3.8 times higher (320 ng L⁻¹) at the pronounced deep CHLa maximum. EZ-integrated phytoplankton carbon averaged 1229 mg C m⁻². Prochlorococcus dominated throughout the EZ, but eukaryotic carbon biomass was ∼4-times greater in the lower than upper EZ, along with a distinct community. In the upper EZ, haptophytes, dinoflagellates and prasinophycean taxa without prasinoxanthin contributed most to monovinyl chlorophyll a (MV-CHLa). In the more diverse lower EZ, haptophytes, dinoflagellates, prasinophycean taxa with prasinoxanthin, pelagophytes, and cryptophytes were the main contributors to MV-CHLa. Diatoms were a minor part of the community. A higher percentage of the upper EZ community showed mixotrophy (35–84%) relative to the lower EZ (30–51%). Nitrogen-fixing organisms (as symbionts of diatoms and free-living cyanobacteria taxa) were ubiquitous, but low in abundance. Overall, community characteristics were similar to those at the Hawaii Ocean Time-series site and the central Gulf of Mexico.

浮游植物是海洋食物网的基础生物，在东印度洋的印度尼西亚通流区（南蓝鳍金枪鱼的产卵区）很少被研究。在此，我们基于流式细胞术、显微镜、分类群特异性色素和rRNA基因测序的互补方法，评估了该地区浮游植物的丰度、生物量、大小结构、色素组成、分类多样性和功能性混合营养物的百分比。在2022年夏季（1 - 2月），该地区的特征是温暖（高达30.5°C），分层，少营养（氮限制）水域，综合绿化带（EZ）叶绿素a （CHLa）为13 mg m−2。EZ平均CHLa在上层较低（85 ng L−1），在明显的深层CHLa最大值处高3.8倍（320 ng L−1）。ez综合浮游植物碳平均为1229 mg C m−2。原绿球藻在整个生态系统中占主导地位，但真核碳生物量在生态系统的下层比上层高4倍，并有一个明显的群落。在上部EZ区，不含prasinoxanthin的haptopophytes、dinoflagellates和prasinophyseia类群对单叶绿素a （pv - chla）贡献最大。在更多样化的下层生态系统中，交生动物、鞭毛动物、含草黄质的草生动物、上生动物和隐生动物是MV-CHLa的主要贡献者。硅藻是群落的一小部分。上层生态区混合营养的比例（35-84%）高于下层生态区（30-51%）。固氮生物（如硅藻和自由生活的蓝藻分类群的共生体）普遍存在，但丰度较低。总体而言，群落特征与夏威夷海洋时间序列站点和墨西哥湾中部相似。

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引用次数: 0

Hotspots in the heat: Bayesian spatial modeling of Southern Bluefin Tuna larvae in a warming Argo Basin 热点在炎热：南部蓝鳍金枪鱼幼虫在变暖的阿尔戈盆地的贝叶斯空间模型

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: 2026-02-02 DOI: 10.1016/j.dsr2.2026.105605

M. Grazia Pennino , Barbara A. Muhling , Estrella Malca , Raúl Laiz-Carrión , José María Quintanilla , Ricardo Borrego-Santos , Manuel Vargas-Yañez , Francisco Abascal , Lynnath E. Beckley , Michael R. Landry

The Argo Basin, located in the eastern Indian Ocean off northwestern Australia, is the primary spawning ground for Southern Bluefin Tuna (Thunnus maccoyii). Understanding the environmental drivers of larval distribution in this region is essential to anticipate potential climate impacts. Using data from the BLOOFINZ cruise, we applied spatially explicit Bayesian models with Tweedie likelihoods to evaluate the influence of sea surface temperature, sea level anomaly, sea surface salinity, chlorophyll-a concentration, bathymetry, and seabed aspect on larval density (density standardized by filtered volume). The best-supported model revealed strong nonlinear responses to temperature, mesoscale activity, and depth. Larval density increased with warmer surface waters, peaked at intermediate depths, and was highest under moderate sea level anomalies, suggesting that retention and feeding conditions are maximized under these circumstances. Seabed aspect had a negative effect, consistent with topography-flow interactions that can reduce retention. The spatial component of the model identified a hotspot of larval density in the southern–southwestern basin and lower density toward the north, with lowest uncertainty in well-sampled central areas. Projections for 2050 under a mid-range climate scenario indicated a heterogeneous redistribution of suitable larval habitat, with declines in central and southeastern spawning areas and increases toward the northeast. These findings highlight the sensitivity of Southern Bluefin Tuna larvae to oceanographic conditions and climate change, and they emphasize the need for adaptive, climate-informed management of spawning habitats.

Argo盆地位于澳大利亚西北部的东印度洋，是南蓝鳍金枪鱼（Thunnus maccoyii）的主要产卵场。了解该地区幼虫分布的环境驱动因素对于预测潜在的气候影响至关重要。利用BLOOFINZ巡航的数据，我们应用空间显式贝叶斯模型和Tweedie似然来评估海面温度、海平面异常、海面盐度、叶绿素-a浓度、水深和海床方面对幼虫密度的影响（通过过滤体积标准化密度）。最佳支持模式揭示了对温度、中尺度活动和深度的强烈非线性响应。幼虫密度随表层水温升高而增加，在中等深度达到峰值，在中等海平面异常情况下最高，表明在这些情况下，幼虫的滞留和摄食条件最大。海底方面有负面影响，与地形-流动相互作用一致，可以减少保留率。模型的空间分量表明，西南盆地南部是幼虫密度的热点地区，北部密度较低，采样良好的中部地区不确定性最低。对2050年中期气候情景的预测表明，适合幼虫栖息地的再分配呈异质性，中部和东南部产卵区减少，东北部产卵区增加。这些发现突出了南方蓝鳍金枪鱼幼虫对海洋条件和气候变化的敏感性，并强调了对产卵栖息地进行适应性、气候知情管理的必要性。

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引用次数: 0

Decadal spatial trends in the feeding-type composition of Arctic deep-sea nematodes at LTER-HAUSGARTEN: A dual classification approach LTER-HAUSGARTEN北极深海线虫食性组成的年代际变化趋势：双重分类方法

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: 2026-01-16 DOI: 10.1016/j.dsr2.2026.105601

Jannik Schnier , Christiane Hasemann

This study examined functional changes in free-living meiobenthic nematode communities across different water depths and sediment layers over a 20-year period along a bathymetric transect at LTER observatory HAUSGARTEN in the Fram Strait (1200 m, 2500 m, and 4000 m). The focus was on changes in feeding type composition and comparing the performance two different classification systems (Wieser's and Hodda's) to assess whether they yield consistent functional interpretations or highlight differences.

Published datasets were used to analyse nematode communities, with specimens identified morphologically to the lowest possible taxonomic level and assigned to feeding types. The study investigated how the trophic structure of nematode communities varied over time, with depth, and between sediment layers, aiming to reveal long-term spatio-temporal patterns at HAUSGARTEN.

Microbial feeding nematodes were consistently dominant across all stations and years. While feeding type composition changed significantly over time at each respective station and to a similar strength with water depth, sediment layer had a stronger influence than the temporal variation. Interannual variation of feeding types as well as within-group dissimilarity and dispersion were lowest at the shallowest station and increased with water depth. Similarly, feeding-type composition in the uppermost sediment layer remained most stable over the years and was gradually decreasing with sediment depth. Despite a decline in nematode abundances over time, the overall feeding type composition remained unchanged. Both classification systems produced comparable results, indicating that functional interpretations of nematode communities are robust across classification approaches.

本研究考察了20年来Fram海峡（1200米，2500米和4000米）的LTER观测站HAUSGARTEN的水深样带上不同水深和沉积层的自由生活的低底生线虫群落的功能变化。重点是饲料类型组成的变化，并比较两种不同分类系统（Wieser和Hodda）的性能，以评估它们是否产生一致的功能解释或突出差异。已发表的数据集被用于分析线虫群落，标本在形态学上被识别到尽可能低的分类水平，并被分配到摄食类型。研究了线虫群落的营养结构如何随时间、深度和沉积物层之间的变化而变化，旨在揭示HAUSGARTEN的长期时空格局。微生物取食线虫在所有站点和年份中始终处于优势地位。各站点的供料类型组成随时间变化显著，且随水深变化的强度相似，但沉积物层的影响强于时间变化。饵料类型的年际变化以及组内差异和分散度在最浅的站点最低，随水深的增加而增加。同样，最上层沉积物的喂养型组成在多年中保持最稳定，并随着沉积物深度的增加而逐渐减少。尽管线虫丰度随着时间的推移而下降，但总体摄食类型组成保持不变。两种分类系统都产生了可比较的结果，表明线虫群落的功能解释在各种分类方法中都是可靠的。

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引用次数: 0

An eastward branch of the east India coastal current off Sri Lanka: Dynamics, formation mechanisms, and impacts on Bay of Bengal salinity variability 斯里兰卡外东印度海岸流的东支：动力、形成机制和对孟加拉湾盐度变化的影响

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: 2026-01-08 DOI: 10.1016/j.dsr2.2025.105588

W.G. Indunil Tharaka Gunathilaka , JayarathnaW.N.D. Sandaruwan , Wang Tianyu , Yan Du

The East India Coastal Current (EICC) flows equatorward during early boreal winter, transporting low–salinity Bay of Bengal (BOB) waters southward along the Indian eastern coast. Using satellite measurements, in–situ observations, and ocean model data, we identify a recurrent eastward current (EC) that splits from the EICC off the eastern coast of Sri Lanka. While a weaker branch of the EICC continues equatorward along the coast, a section of rest flow diverts northeastward into the BOB as the EC, indicating a gyre structure in the northwest of BOB. Analysis of 28 years of data (1993–2020) reveals eight distinct EC events, occurring primarily during neutral Indian Ocean dipole years. These events are dynamically forced by two types of eddies, a westward–propagating anticyclonic eddy, linked to downwelling Rossby waves, impinging on the south eastern coast of Sri Lanka, while a cyclonic eddy forms to the north. These events are supported by the following coastal–trapped downwelling Kelvin wave, with the current appearing with increasing frequency over time. The EC, lasting about one-two weeks, exhibits a velocity of 0.3–0.5 m/s and transport flow volume ranging from 0.15 to 0.54 Sv. Despite its brief duration, EC plays a critical role in exporting low–salinity waters (<33 PSU) from Sri Lanka's eastern coast and subsequently transporting high–salinity central BOB waters toward the inner bay. By regulating EICC low–salinity water intrusion, the EC produces distinct freshening effects along Sri Lanka's eastern coast during active years, highlighting its important role in controlling western BOB freshwater distribution patterns.

东印度海岸流（EICC）在北纬初冬向赤道流动，将低盐度的孟加拉湾（BOB）水沿印度东海岸向南输送。利用卫星测量、现场观测和海洋模型数据，我们确定了一个从斯里兰卡东海岸的EICC分裂出来的周期性东流（EC）。当EICC的一个较弱分支沿着海岸继续向赤道方向移动时，一部分剩余气流转向东北进入BOB作为EC，表明BOB西北部存在环流结构。对28年（1993-2020）数据的分析揭示了8个不同的EC事件，主要发生在印度洋中性偶极子年。这些事件是由两种类型的涡流动态推动的，一种是向西传播的反气旋涡流，与下行的罗斯比波有关，撞击斯里兰卡的东南海岸，而一种是在北部形成的气旋涡流。这些事件是由以下海岸捕获的下潜开尔文波支持的，随着时间的推移，水流出现的频率越来越高。EC持续约1 - 2周，流速为0.3-0.5 m/s，输送流量为0.15 - 0.54 Sv。尽管持续时间很短，但东印度洋在从斯里兰卡东海岸出口低盐度水域（<33 PSU）以及随后将高盐度的BOB中部水域输送到内湾方面发挥了关键作用。通过调节EICC低盐度水入侵，EC在斯里兰卡东部沿海活跃年产生明显的清新效应，突出了其在控制西部BOB淡水分布模式中的重要作用。

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引用次数: 0

Microbial and chemical signatures of melting sea-ice: export of bacteria, microeukaryotes, and molecules 海冰融化的微生物和化学特征：细菌、微真核生物和分子的输出

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: 2026-02-07 DOI: 10.1016/j.dsr2.2026.105607

Magda G. Cardozo-Mino , Julian Merder , Thorsten Dittmar , Antje Boetius , Matthias Wietz

Sea-ice loss in the warming Arctic Ocean profoundly affects microbial communities and biogeochemical cycles. Here, we performed a microcosm experiment with sea-ice and seawater from the Fram Strait to identify microbial and chemical signatures of melting ice and the surrounding seawater. Amplicon sequencing across 49 h of incubation showed that approximately one-tenth of bacterial and microeukaryotic taxa were directly traceable between the original ice and meltwater. Exported microbes included diatoms (for example Attheya, Navicula, Bacillaria), heterotrophic protists (for example Pelagophyceae, MAST-12B, Thoracosphaeraceae), and bacteria (for example Psychroflexus, Taeseokella, Lewinella). Size-fractionated filtration showed that mostly larger cells and aggregates, including chytrid fungi and biofilm-forming bacteria, seeded the meltwater microbiome. FT-ICR-MS revealed a prevalence of aliphatic and sulfuric molecular formulae in the original sea-ice. Of the 128 formulae unique to sea-ice, 10 were subsequently detected in meltwater. Up to 26% of organic molecules in sea-ice were shared with other Arctic datasets, indicating pan-Arctic patterns in sea-ice chemistry. Together, the finding of distinct 'ice signatures' in meltwater illustrates microbial and chemical connectivity between these habitats, with implications for the biological carbon pump and cryobenthopelagic coupling.

变暖的北冰洋海冰的减少深刻地影响着微生物群落和生物地球化学循环。在这里，我们对来自弗拉姆海峡的海冰和海水进行了微观实验，以确定融化的冰和周围海水的微生物和化学特征。经过49小时孵育的扩增子测序显示，大约十分之一的细菌和微真核生物分类群在原始冰和融水之间可以直接追踪。出口的微生物包括硅藻（如Attheya、Navicula、Bacillaria）、异养原生生物（如Pelagophyceae、MAST-12B、胸osphaeraceae）和细菌（如Psychroflexus、Taeseokella、Lewinella）。大小分级过滤显示，大部分较大的细胞和聚集体，包括壶菌和生物膜形成细菌，播种了融水微生物群。FT-ICR-MS显示原始海冰中普遍存在脂肪族和硫族分子式。在海冰特有的128个公式中，随后在融水中发现了10个。海冰中高达26%的有机分子与其他北极数据集共享，这表明了海冰化学的泛北极模式。总之，在融水中发现的独特的“冰特征”说明了这些栖息地之间的微生物和化学连通性，对生物碳泵和低温底藻耦合具有重要意义。

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引用次数: 0

Zooplankton trophic processes in the eastern Indian Ocean off northwest Australia 澳大利亚西北部东印度洋浮游动物的营养过程

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: 2026-01-13 DOI: 10.1016/j.dsr2.2026.105592

Moira Décima , Rasmus Swalethorp , Grace F. Cawley , Claudia Traboni , Claire H. Davies , Michael R. Landry

The region off northwestern Australia in the eastern Indian Ocean is an oligotrophic open-ocean ecosystem characterized by low nutrients and high stratification, and is the only known spawning ground for Southern Bluefin Tuna (SBT). We conducted four multi-day Lagrangian experiments (cycles) and transect sampling to investigate plankton trophic flows during the peak SBT spawning season (Jan–Feb 2022). These cycles were carried out after recent storm mixing and subsequent warming and stratification of the water column. We quantified mesozooplankton size-fractionated biomass and grazing, targeting processes that coincide with SBT larval habitat (upper 30 m) and the full euphotic zone (150 m). Higher grazing occurred in the upper 30 m at the start of our study, coinciding with the deeper mixed layer. Euphotic-zone integrated grazing peaked later, coinciding with higher stratification and increased abundance of diatoms at depth. Mesozooplankton grazing impact averaged 0.11 ± 0.01 d^-1 for the region, equivalent to 21.2 % of phytoplankton growth. Combined with microzooplankton grazing removals, phytoplankton growth and total zooplankton grazing losses were approximately in balance for the euphotic zone. While direct consumption of phytoplankton only supported respiratory needs of a portion of the assemblage in two of the four experimental cycles, respiratory and production needs were largely met by including the consumption of microzooplankton production. Thus, the production of mesozooplankton prey required to sustain SBT larvae in this nutrient-poor environment was obtained by both high grazing and efficient trophic coupling. This study highlights the role of metazoan zooplankton in warm oligotrophic waters of the eastern tropical Indian Ocean, and indicates that efficient ecosystem transfer can be achieved even under conditions assumed to severely limit production and biomass accumulation.

东印度洋澳大利亚西北部海域是一个营养不良的开放海洋生态系统，其特点是低营养和高分层，是唯一已知的南蓝鳍金枪鱼（SBT）的产卵场。通过4个多天拉格朗日实验（循环）和样带取样，研究了SBT产卵高峰期（2022年1 - 2月）浮游生物的营养流动。这些循环是在最近的风暴混合和随后的水柱变暖和分层之后进行的。我们量化了中浮游动物的大小-分异生物量和放牧，目标过程与SBT幼虫栖息地（30米以上）和全光带（150米）一致。在我们的研究开始时，较高的放牧发生在30 m以上，与较深的混合层相一致。光带综合放牧的高峰较晚，与较高的分层和深度硅藻丰度增加相一致。该地区中浮游动物的放牧影响平均为0.11±0.01 d-1，相当于浮游植物生长的21.2%。结合微小浮游动物的放牧去除，浮游植物的生长和浮游动物的总放牧损失在真光区大致平衡。虽然在四个实验周期中的两个周期中，浮游植物的直接消耗仅支持部分组合的呼吸需要，但通过包括微型浮游动物生产的消耗，呼吸和生产需要在很大程度上得到满足。因此，在这种营养匮乏的环境中，维持SBT幼虫所需的中浮游动物猎物的生产是通过高放牧和有效的营养耦合来实现的。本研究强调了热带印度洋东部温暖少营养水域的后生动物浮游动物的作用，并表明即使在严重限制生产和生物量积累的条件下，也可以实现有效的生态系统转移。

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引用次数: 0

More than co-occurrence: what amplicon time series data can tell us 不仅仅是共现：放大时间序列数据能告诉我们什么

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: 2026-01-30 DOI: 10.1016/j.dsr2.2026.105599

Ellen Oldenburg , Nima P. Saadat , Sofie Thielen , Ovidiu Popa

The Arctic Ocean is undergoing unprecedented transformations due to climate change, with rising temperatures, shrinking sea ice, and shifting oceanographic conditions reshaping its ecosystem. At the center of these changes lie the Arctic's microbial communities that drive biogeochemical cycles, sustain primary production, and maintain ecosystem stability. Long-term ecological research is essential for understanding microbial community dynamics and their role in biogeochemical cycles, particularly in polar ecosystems. The HAUSGARTEN observatory, established in 1999, has provided unparalleled insights into Arctic marine microbial ecology. This review synthesizes 25 years of microbial re-search at HAUSGARTEN, revealing how advanced methodologies—such as amplicon sequencing, which has revolutionized microbial ecology by enabling the taxonomic characterization of complex communities through targeted marker genes, Fourier decomposition, Convergent Cross Mapping (CCM), and Energy Landscape Analysis (ELA)—have revolutionized our understanding of Arctic microbial ecology. By integrating time-series data with network-based approaches, we move beyond static snapshots to uncover the hidden rhythms of microbial life, from seasonal successions to long-term trends. We explore the interplay between environmental drivers and microbial community structure, emphasizing seasonal succession, functional adaptations, and the impact of Atlantification. Environmental conditions are constantly changing; therefore, there is a need for predictive models. By combining machine learning, deterministic modeling, and ecological theory, we are now poised to forecast how microbial communities will respond to future climate scenarios. From Graph Neural Networks (GNNs) to ARIMA forecasting, this review showcases the power of amplicon data in a time series frame work together with interdisciplinary approaches to tackle one of the most pressing challenges of our time. Arctic microbial communities are the key to understanding and mitigating the impacts of climate change, and this review is a guide to unlocking their secrets.

由于气候变化，北冰洋正在经历前所未有的变化，气温上升、海冰萎缩、海洋条件变化重塑了其生态系统。这些变化的核心是北极的微生物群落，它们推动生物地球化学循环，维持初级生产，维持生态系统稳定。长期生态学研究对于理解微生物群落动态及其在生物地球化学循环中的作用至关重要，特别是在极地生态系统中。HAUSGARTEN观测站成立于1999年，提供了对北极海洋微生物生态的无与伦比的见解。这篇综述综合了HAUSGARTEN 25年的微生物研究，揭示了先进的方法，如扩增子测序，它通过目标标记基因、傅立叶分解、收敛交叉映射（CCM）和能量景观分析（ELA）来实现复杂群落的分类特征，从而彻底改变了微生物生态学，彻底改变了我们对北极微生物生态学的理解。通过将时间序列数据与基于网络的方法相结合，我们超越了静态快照，揭示了微生物生命的隐藏节奏，从季节性演替到长期趋势。我们探讨了环境驱动因素与微生物群落结构之间的相互作用，强调了季节演替、功能适应和大西洋化的影响。环境条件不断变化；因此，有必要建立预测模型。通过结合机器学习、确定性建模和生态学理论，我们现在准备预测微生物群落将如何应对未来的气候情景。从图神经网络（gnn）到ARIMA预测，本综述展示了时间序列框架中放大数据的力量，以及跨学科方法，以解决我们这个时代最紧迫的挑战之一。北极微生物群落是理解和减轻气候变化影响的关键，这篇综述是解开它们秘密的指南。

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引用次数: 0

Selective feeding of southern Bluefin Tuna (Thunnus maccoyii) larvae on appendicularians in their eastern Indian Ocean spawning region 南蓝鳍金枪鱼（Thunnus maccoyii）幼虫在东印度洋产卵区对尾尾鱼的选择性摄食

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.dsr2.2026.105591

Rasmus Swalethorp , Estrella Malca , Akihiro Shiroza , Lindsey Kim , Moira Decima , José M. Quintanilla , Ricardo Borrego-Santos , Claire H. Davies , David Die , Lynnath E. Beckley , Claudia Traboni , Grace F. Cawley , Kamran Walsh , Michael R. Landry , Raúl Laiz-Carrión

We investigated ontogenetic variability in feeding and prey selection by Southern Bluefin Tuna larvae (SBT; Thunnus maccoyii) in their only global spawning region, located in the eastern Indian Ocean between northwestern Australia and Indonesia. Zooplankton prey and SBT larvae were sampled during four multi-day Lagrangian experiments conducted in the southern Argo Basin during the peak midsummer spawning season in January–February 2022. The zooplankton were identified, enumerated, sizes measured, and their developmental stages ascertained both in situ and from the stomach contents of the larvae. Larval stomach contents revealed high feeding incidence of 95 % with at least one prey item ingested with an average of 3.9 zooplankton prey per larva. Diet and prey selection transitioned during larval ontogeny from copepod nauplii to calanoid and corycaeid copepodites, and ultimately to cladocerans, as well as fish larvae when these were available. However, for all developmental stages and experiments, appendicularians stood out as the most significant prey taxon, constituting an average of 57 % of prey carbon biomass consumed and up to 79 % for postflexion stages. We observed some indication of increasing selection for appendicularians and fish larvae where they were most abundant, even when other suitable prey items were more readily available. Our study documents unprecedented high feeding incidence and positive selection for appendicularians compared to previous investigations of bluefin species, highlighting a pathway that enhances food web transfer efficiency. Appendicularians are uniquely able to thrive in oligotrophic environments and could be an optimal food source supporting SBT larvae in the future ocean.

我们研究了南蓝鳍金枪鱼（SBT; Thunnus maccoyii）在其唯一的全球产卵区（位于澳大利亚西北部和印度尼西亚之间的东印度洋）的摄食和猎物选择的个体发育变异性。在2022年1 - 2月的盛夏产卵高峰期，在Argo盆地南部进行了4次多日拉格朗日实验，对浮游动物猎物和SBT幼虫进行了采样。对浮游动物进行了鉴定、枚举，测量了它们的大小，并在原位和从幼虫胃内容物中确定了它们的发育阶段。幼虫胃内容物的摄食率高达95%，至少有一种猎物被摄食，平均每只幼虫捕获3.9种浮游动物。在幼体发育过程中，饮食和猎物选择发生了转变，从鹦鹉螺类桡足类和喙类桡足类，到最终的枝海类，以及有条件的鱼类幼体。然而，在所有发育阶段和实验中，尾虫作为最重要的猎物分类群脱颖而出，平均占猎物碳生物量消耗的57%，在屈曲后阶段高达79%。我们观察到一些迹象表明，即使在其他合适的猎物更容易获得的情况下，尾虫和鱼类幼虫在它们最丰富的地方也会被选择。与以往的研究相比，我们的研究记录了蓝鳍金枪鱼前所未有的高摄食率和正选择，突出了提高食物网转移效率的途径。尾虫在低营养环境中茁壮成长的独特能力，可能是未来海洋中支持SBT幼虫的最佳食物来源。

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引用次数: 0

Seasonal and spatial variability of marine nepheloid layers in the deep South China Sea 南海深海海相网状层的季节和空间变异

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: 2026-01-13 DOI: 10.1016/j.dsr2.2026.105600

Zhuangcai Tian , Xiujun Guo , Jinjian Huang , Chao Xu , Lei Song , Jianhua Yue

Marine nepheloid layers are extensively distributed across the world's oceans and marginal seas, characterized by significantly high turbidity compared to adjacent layers. In this study, we measured four transects located at 6°N, 10°N, 18°N, and 113°E in the South China Sea (SCS), encompassing a total of 75 CTD stations each year, and conducted four sets of repeated measurements over a four-year period. Our findings indicate that the scale and concentration of Bottom Nepheloid Layer (BNL) and Intermediate Nepheloid Layer (INL) vary significantly across different subbasins and seasons. In the southwestern and northwestern subbasin of the SCS, BNL and multiple INLs persist year-round at different water depths. BNL is commonly observed on the continental slope with the INLs extending along the isopycnals, and both BNL and INLs always are stronger in summer. High turbidity has caused marked alterations in the isopycnal and isotherm structures of the water column, particularly near the slope. In the central basin of the SCS, multiple INLs also persist year-round, especially at water depths 400–1000 m. The changes in the water column by high turbidity in the central basin were weaker. The persistent presence of INLs indicates ongoing transport of particulate matter across the slope. Ocean currents and internal waves predominantly affect the slopes of the southwestern and northwestern subbasins, while the deeper central basin is primarily affected by the ocean currents. The interactions between internal waves or ocean currents and submarine topography contribute to the frequent occurrence of BNL and INLs around the seamounts. This paper aimed to provide a comprehensive analysis of the seasonal and spatial variability of BNLs and INLs in the deep SCS, serving as a reference for future research on the dynamic processes of marine ecological environment and associated source-sink systems.

海洋浊体层广泛分布在世界海洋和边缘海，其特点是与邻近层相比浊度明显高。研究中，我们在南海6°N、10°N、18°N和113°E的4个样带上进行了每年75个CTD站点的测量，并在4年的时间里进行了4组重复测量。研究结果表明，不同亚盆地、不同季节，底部和中间云雾层的规模和浓度存在显著差异。在南海西南和西北次海盆，在不同水深，BNL和多个inl全年持续存在。在大陆斜坡上普遍观测到BNL， inl沿等距平线延伸，夏季BNL和inl都较强。高浊度引起了水柱等平线和等温线结构的明显变化，特别是在斜坡附近。在南海的中央盆地，多个inl也全年持续存在，特别是在400-1000米的水深。中部盆地高浊度对水柱的影响较弱。INLs的持续存在表明颗粒物质正在通过斜坡进行输送。洋流和内波主要影响西南和西北次盆地的斜坡，而较深的中央盆地主要受洋流的影响。内波或海流与海底地形的相互作用是海底山附近频繁发生的海底低洼和海底低洼的重要原因。本文旨在全面分析南海深层生物碱和生物碱的季节和空间变异，为进一步研究海洋生态环境的动态过程和相关的源汇系统提供参考。

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引用次数: 0

The Second International Indian Ocean Expedition (IIOE-2): Motivating new exploration in a poorly understood ocean basin (volume 7) 第二次国际印度洋考察（IIOE-2）：在一个知之甚少的海洋盆地激发新的探索（第7卷）

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: 2026-01-16 DOI: 10.1016/j.dsr2.2025.105566

Raleigh R. Hood , Lynnath E. Beckley , V.V.S.S. Sarma , P.N. Vinayachandran

引用次数: 0