Deep-sea Research Part Ii-topical Studies in Oceanography最新文献_第3页

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 : 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

Interaction of bay outflow and wind-driven upwelling in chlorophyll patterns in the Gulf of the Farallones 法拉隆湾叶绿素模式中海湾流出流与风驱动上升流的相互作用

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2025-12-01 DOI: 10.1016/j.dsr2.2025.105558

Candice N. Cooper , Christopher A. Edwards , John L. Largier , Piero L.F. Mazzini

A descriptive analysis of remotely-sensed surface chlorophyll-a within the Gulf of the Farallones and nearby coastal waters occupying portions of three NOAA National Marine Sanctuaries along the central California coast is presented. The seasonal cycle from a 25-year chlorophyll-a record reveals elevated levels near the mouth of San Francisco Bay at the Golden Gate, with broad spatial extent climatologically from April through November. A 19-year time series of normalized water-leaving radiance at the 555 nm band (nLw555) was used to estimate the presence of waters representing the San Francisco Bay plume. Although the plume shows its largest spatial extent in winter, decreasing during spring and summer, chlorophyll-a was enhanced within plume waters relative to non-plume waters during all months; however, was not statistically different during upwelling months (April–June). Linear correlations between chlorophyll-a and a 20-year record of wind stress, a 10-year record of surface currents, and a 20-year record of sea surface temperatures reveal consistent, coherent regional spatial patterns. Weighted averages confirm that poleward winds and surface currents result in enhanced chlorophyll-a in nearshore waters north of the Golden Gate and around Point Reyes. Periods of equatorward winds and surface transport exhibit elevated chlorophyll-a and temperature south of the Golden Gate, offshore of Half Moon Bay, and are associated with nearby onshore currents. Correlations of plume concentrations (nLw555

\geq 12

W m⁻²

μ

m⁻¹ sr⁻¹) with wind stress, however, do not show the same coherent patterns as with chlorophyll-a, and turbid plume waters are largely confined to the Gulf of the Farallones. These analyses suggest that surface chlorophyll-a within the inner Gulf of the Farallones close to San Francisco Bay is significantly influenced by outflow from the Bay, but the greater Gulf of Farallones is more strongly influenced by upwelling and relaxation effects.

本文对法拉隆湾和位于加州中部海岸的三个NOAA国家海洋保护区附近的沿海水域的遥感地表叶绿素- A进行了描述性分析。从25年的叶绿素记录的季节周期来看，在金门湾的旧金山湾口附近，从4月到11月，在气候上具有广泛的空间范围，叶绿素水平升高。在555nm波段（nLw555）的19年标准化水离开辐射时间序列被用来估计代表旧金山湾羽流的水的存在。尽管羽流的空间范围在冬季最大，在春夏两季逐渐减小，但在所有月份中，羽流水体内的叶绿素a均比非羽流水体增强；而在上升流月份（4 - 6月），差异无统计学意义。叶绿素-a与20年风应力记录、10年地表洋流记录和20年海面温度记录之间的线性相关揭示了一致的、连贯的区域空间格局。加权平均值证实，在金门以北和雷耶斯角附近的近岸水域，向极地方向的风和表面洋流导致叶绿素-a的增加。在金门以南，半月湾近海，赤道风和地面运输的时期，叶绿素-a和温度升高，并与附近的陆上洋流有关。然而，羽流浓度（nLw555≥12 W m−2 μm−1 sr−1）与风应力的相关性与叶绿素-a的相关性不一致，并且浑浊的羽流水主要局限于Farallones湾。这些分析表明，在靠近旧金山湾的Farallones内湾，表层叶绿素-a受到海湾流出物的显著影响，但Farallones大湾受上升流和松弛效应的影响更为强烈。

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引用次数: 0

Primary productivity and N2-fixation in the eastern Indian ocean: Bottom-up support for an ecologically and economically important ecosystem 东印度洋的初级生产力和氮固定：对生态和经济重要生态系统的自下而上支持

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2025-11-25 DOI: 10.1016/j.dsr2.2025.105570

Sven A. Kranz , Jared M. Rose , Michael R. Stukel , Karen E. Selph , Natalia Yingling , Michael R. Landry

Oligotrophic ocean regions are characterized by strong nutrient limitation, low standing phytoplankton biomass, and highly efficient nutrient recycling. During the BLOOFINZ-IO expedition (February 2022), we quantified nutrient inventories, primary productivity and N₂ fixation in the Argo Basin of the eastern Indian Ocean, the sole known spawning ground for Southern Bluefin Tuna. Low concentrations of surface nitrate (<0.02 μmol L⁻¹) and persistent residual phosphate indicated N as the limiting macronutrient, with photophysiological indices consistent with iron colimitation. Depth-integrated net primary production (NPP), from ¹⁴C-based in-situ incubations during 4 Lagrangian experiments, averaged ∼460 mg C m⁻²d⁻¹, generally agreeing with mean satellite-based NPP estimates (459 mg C m⁻²d⁻¹) but with spatial discrepancies. Nitrogen fixation provided a consistent new nitrogen source, contributing ∼16 % to local NPP in the upper euphotic zone. Gross primary production (GPP), from fast-repetition-rate-fluorometry-based estimates of electron transport, revealed significant autotrophic respiration losses, with mean GPP:NPP ratios of ∼1.8 consistent with metabolic costs under nutrient limitation. Net community production (NCP) from O₂/Ar ratios averaged ∼20 % of NPP in the upper 30 m. This result, in combination with N₂ fixation measurement, indicates that N₂ fixation supports most of the export production in the region. Together, the multi-method approach revealed a recycling-dominated ecosystem affected by episodic mixing events, where primary productivity is maintained primarily through efficient nitrogen recycling and physiological photoacclimation. These results provide a comprehensive baseline of bottom-up support of ecosystem productivity for the Argo Basin for assessing future climate-driven changes in stratification, nutrient cycling, and food-web dynamics.

低营养海洋区具有养分限制强、浮游植物生物量低、养分循环效率高的特点。在BLOOFINZ-IO考察期间（2022年2月），我们量化了东印度洋Argo盆地（已知唯一的南蓝鳍金枪鱼产卵地）的营养库存、初级生产力和N2固定。低浓度的表面硝酸盐（<0.02 μmol L−1）和持久残留的磷酸盐表明N是限制性常量养分，其光生理指标与铁共生一致。在4次拉格朗日实验中，基于14c的原位孵育的深度综合净初级产量（NPP）平均为~ 460 mg C m−2d−1，与基于卫星的平均NPP估算值（459 mg C m−2d−1）大致一致，但存在空间差异。固氮提供了一致的新氮源，对高光区局部NPP贡献约16%。根据基于快速重复率荧光测量的电子传递估计，总初级产量（GPP）显示了显著的自养呼吸损失，GPP:NPP的平均比率为1.8，与营养限制下的代谢成本一致。O2/Ar比值产生的群落净产量（NCP）平均为30米上游NPP的20%。这一结果与N2固定测量相结合，表明N2固定支持该地区的大部分出口生产。总之，多方法方法揭示了一个以循环为主的生态系统，受偶发性混合事件的影响，其中初级生产力主要通过有效的氮循环和生理光驯化来维持。这些结果为Argo盆地生态系统生产力自下而上的支持提供了一个全面的基线，用于评估未来气候驱动的分层、养分循环和食物网动态变化。

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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 : 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

Vertical distribution and environmental drivers of meiofaunal communities in the Persian Gulf: insights into biodiversity and sediment dynamics 波斯湾小型动物群落的垂直分布和环境驱动因素：对生物多样性和沉积物动力学的见解

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2025-11-24 DOI: 10.1016/j.dsr2.2025.105571

Narges Badri , Behrooz Abtahi , Abolfazl Saleh , Homira Agah , Hans-Peter Grossart

Unlike earlier studies conducted in shallow coastal areas, this study is the first to examine the vertical distribution of meiofaunal communities at depths ranging from 10 to 93 m at five stations in the northern semi-enclosed Persian Gulf. Among the sampled stations, the highest meiofauna density was observed at Station 2, with an average of 2398 ± 921.4 individuals per 10 cm², while the lowest abundance was recorded at Station 4, amounting to 444.3 ± 96.2 individuals per 10 cm². A comprehensive analysis of 20311 meiofauna individuals representing 29 taxa revealed several dominant groups. Free-living nematodes (51.98 %), foraminifera (27.88 %), copepods (4.9 %), juvenile bivalves (2.79 %), polychaetes (2.76 %), and oligochaetes (2.39 %) comprised together 93 % of the community. The vertical distribution profile indicated that 91 % of the Persian Gulf meiofauna were concentrated in the top 2–3 cm sediment layer, although some were found at depths exceeding 5 cm. The nematode complex exhibited a diverse composition, with 90 genera from 30 families and 7 orders identified across the study sites. Environmental parameters, including sediment characteristics, i.e., dissolved oxygen (DO) as the strongest driver, total organic matter (TOM), grain size, and water depth, emerged as critical factors influencing meiofaunal abundance and diversity. Based on the Environmental Quality Standards (EQS) classification, the sampling stations demonstrated high to good EQS compliance.

与之前在浅海地区进行的研究不同，这项研究是第一次在波斯湾北部半封闭的五个站点，在深度从10米到93米的范围内检查小型动物群落的垂直分布。其中，2号站的数量最多，平均为2398±921.4只/ 10 cm2； 4号站的数量最少，平均为444.3±96.2只/ 10 cm2。对29个分类群的20311个珍稀动物个体进行综合分析，发现了几个优势群。线虫（51.98%）、有孔虫（27.88%）、桡足类（4.9%）、双壳类幼体（2.79%）、多毛类（2.76%）和寡毛类（2.39%）共占群落的93%。垂直分布剖面表明，91%的波斯湾小型动物集中在2 ~ 3 cm的沉积物层上，尽管在深度超过5 cm的地方也发现了一些。线虫复合体显示出多样化的组成，在整个研究地点鉴定出30科7目90属。环境参数，包括沉积物特征，即溶解氧（DO）是最强的驱动因素，总有机质（TOM），粒度和水深是影响微量动物丰度和多样性的关键因素。根据环境质量标准（EQS）分类，采样站符合环境质量标准（EQS）。

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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 : 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

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 : 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

Acidic vacuole-containing organisms are a majority of the eukaryotic microbial community in oligotrophic Argo Basin waters (eastern Indian ocean) 酸性液泡生物是贫营养Argo盆地（东印度洋）水体中真核微生物群落的主要组成部分。

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2025-11-17 DOI: 10.1016/j.dsr2.2025.105563

Karen E. Selph , Natalia Yingling , Claudia Traboni , Michael R. Landry

The Argo Basin of the eastern Indian Ocean in austral summer (February 2022) was characterized by warm (28.5–30.6 °C), oligotrophic surface waters (nitrate and phosphate ≤0.1 μM), with relatively shallow mixed layers and deep chlorophyll biomass maxima. From euphotic zone depth-resolved samples analyzed by for DNA and acid vacuole staining (Hoechst and LysoTracker Green) by ship-board flow cytometry, we found that autotrophic populations were dominated by Prochlorococcus, followed by mixotrophs (58 and 28 % of autotrophic community biomass, respectively), with only 14 % obligate phototrophic phytoplankton (i.e., plastidic cells without acid vacuole fluorescence). Acid vacuole-containing microbes (mixotrophs and heterotrophs) were 34 % of the microbial community, and 80 % of the eukaryotic biomass. In shallow waters, the eukaryotic chlorophyll-containing community was comprised of pico-sized obligate phototrophs and mixotrophs (233–325 cells mL⁻¹), nano-sized obligate phototrophs and mixotrophs (72 and 374 cells mL⁻¹, respectively), with all groups increasing several-fold in the deep chlorophyll maxima. Mixotrophs were a higher proportion of the chlorophyll-containing community in the shallow nutrient-poor mixed layer, consistent with a nutrient-acquisition argument for their prevalence. Heterotrophic eukaryotes averaged 524 ± 36 cells mL⁻¹ in the euphotic zone, changing little with depth and showing a significant positive relationship with Prochlorococcus, but not any other group. In contrast, mixotrophs were positively correlated with heterotrophic bacteria, but not with Prochlorococcus. Overall, the high proportion of mixotrophs in the microbial community may channel more productivity to higher trophic levels than expected given the region's nutrient-poor status.

南夏季（2022年2月）东印度洋Argo盆地呈现温暖（28.5 ~ 30.6°C）、低营养表层水（硝酸盐和磷酸盐≤0.1 μM）、较浅混合层和较深叶绿素生物量最大值的特征。通过船上流式细胞术对DNA和酸性液泡染色（Hoechst和LysoTracker Green）分析的嗜光带深度分辨样品，我们发现自养种群以原绿球藻为主，其次是混合营养菌（分别占自养群落生物量的58%和28%），只有14%专性光养浮游植物（即没有酸性液泡荧光的塑料细胞）。含酸液泡微生物（混合营养体和异养体）占微生物群落的34%，占真核生物生物量的80%。在浅水中，真核生物含叶绿素群落由微型专性光养生物和混合营养体（233-325个细胞mL−1）、纳米级专性光养生物和混合营养体（分别为72和374个细胞mL−1）组成，所有组在深层叶绿素最大值时都增加了数倍。混合营养体在浅层营养贫乏的混合层中含有叶绿素的群落中所占比例较高，这与它们普遍存在的营养获取论点一致。异养真核生物在嗜光区平均为524±36个细胞mL−1，随深度变化不大，与原绿球藻呈显著正相关，其他组无显著正相关。混合营养菌与异养菌呈显著正相关，与原绿球藻无显著正相关。总体而言，考虑到该地区营养贫乏的状况，微生物群落中混合营养体的高比例可能会将更多的生产力引导到更高的营养水平。

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引用次数: 0

Ecological risk assessment and distribution pattern of heavy metal contamination in mangrove sediments at Bushehr Province, West-northern Persian Gulf, Iran 伊朗波斯湾西部-北部布什尔省红树林沉积物重金属污染生态风险评价及分布格局

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2025-11-11 DOI: 10.1016/j.dsr2.2025.105565

Homira Agah , Zahra Eslami , Maryam Ghaemi

Mangrove ecosystems function as natural biogeochemical filters and can retain substantial amounts of heavy metals from terrestrial and marine sources. Given increasing global concern over metal contamination in coastal sediments, assessing heavy-metal levels in mangrove habitats is essential for evaluating ecosystem health. Mangrove forests in Bushehr Province, Iran, are located near industrial and coastal development zones, raising concern about potential ecological risks.

This study assessed concentrations and ecological risks of heavy metals in 78 surface sediment samples collected from three mangrove areas (Bardestan, Mel Ganzeh, and Nayband). Metal concentrations were determined using ICP-MS following acid digestion. The abundance of elements followed the order Al > Fe > Mn > V > Cr > Ni > Cu > Zn > As > Se > Mo > Co > Pb > Cd > Bi. Significant positive correlations among most metals (Mn, Cr, V, Zn, Cu, Ni, As, Cd, P < 0.05) indicated predominantly natural sources, except for Se. Ni concentrations in Mel Ganzeh and deeper Bardestan stations exceeded the Threshold Effect Level (19.7 mg kg⁻¹), while other metals remained below guideline values. Contamination and enrichment indices confirmed generally natural origin (except for Se) and low enrichment. According to the results, the pattern of elements accumulation in sediments of the studied areas was as the following order: Mel Ganzeh > Bardestan > Nayband > Coastal parts of Nayband. Overall, ecological risk indices indicated low risk, suggesting that current heavy-metal inputs do not pose a significant threat to mangrove sediments in Bushehr Province.

红树林生态系统起着天然生物地球化学过滤器的作用，可以保留大量来自陆地和海洋的重金属。鉴于全球对沿海沉积物中的金属污染日益关注，评估红树林栖息地的重金属水平对于评估生态系统健康至关重要。伊朗布什尔省的红树林位于工业和沿海开发区附近，这引起了人们对潜在生态风险的担忧。本研究评估了从三个红树林地区（Bardestan、Mel Ganzeh和Nayband）收集的78个表层沉积物样本中的重金属浓度和生态风险。酸消化后用ICP-MS测定金属浓度。元素的丰度之后订单Al祝辞Fe祝辞Mn在V祝辞Cr在倪祝辞铜在锌在祝辞,Se在密苏里州的在公司的在Pb在Cd在Bi。除Se外，大多数金属（Mn, Cr， V, Zn, Cu, Ni, As, Cd, P < 0.05）之间呈显著正相关，表明主要是天然来源。Mel Ganzeh和Bardestan更深的站点的Ni浓度超过了阈值效应水平（19.7 mg kg - 1），而其他金属仍低于指导值。污染和富集指标一般证实为天然来源（硒除外）和低富集。结果表明，研究区沉积物中元素的富集规律为：Mel Ganzeh >； Bardestan > Nayband >； Nayband海岸部分。总体而言，生态风险指数显示为低风险，表明目前的重金属输入对布什尔省红树林沉积物不构成重大威胁。

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引用次数: 0

Overview of BLOOFINZ/INDITUN investigations of the southern bluefin spawning region off northwest Australia, January–March 2022 2022年1月至3月，对澳大利亚西北部南部蓝鳍金枪鱼产卵区进行的BLOOFINZ/INDITUN调查概述

IF 3 3区地球科学 Q2 OCEANOGRAPHY

Deep-sea Research Part Ii-topical Studies in Oceanography

Pub Date : 2025-11-09 DOI: 10.1016/j.dsr2.2025.105564

Michael R. Landry , Raúl Laiz-Carrión , Sven A. Kranz , Karen E. Selph , Michael R. Stukel , Estrella Malca , David Die , Lynnath E. Beckley , Moira Décima , Rasmus Swalethorp , José M. Quintanilla , Natalia Yingling , Claire H. Davies , Claudia Traboni , Ricardo Borrego-Santos , Joaquim I. Goes , Ariana de Souza , Patricia Romero-Fernández , M. Grazia Pennino , Lindsey E. Kim , Luke Matisons

Southern Bluefin Tuna (SBT, Thunnus maccoyii) range broadly in rich feeding grounds of the Southern Hemisphere but spawn only in a small tropical region off northwestern Australia directly downstream of the Indonesian Throughflow. Here, we describe goals, physical context, design and major findings of an end-to-end process study conducted during the peak SBT spawning season (January–March 2022) to understand nutrient sources, productivity, pelagic food web structure and their relationships to larval SBT feeding, growth and survival. Mesoscale variability was investigated by continuous underway measurements of surface waters and station sampling along the cruise track. Biogeochemical and community relationships, process rates, and trophic interactions were determined in four multi-day Lagrangian experiments in the southern Argo Basin. The study revealed strong system balances among nitrogen fluxes, phytoplankton production, grazing processes, and export. Highly selective feeding on appendicularians allows efficient trophic transfer from picophytoplankton-dominated production to SBT larvae. Plankton productivity, phytoplankton carbon and zooplankton biomass were proportionately elevated compared to similar measurements from the Atlantic bluefin larval habitat in the Gulf of Mexico, but with less advective input from the coastal margins. Individual-based otolith and stable isotope analyses identify larvae of low trophic position, narrow diet, and narrow maternal diet as the fastest growers most likely to contribute to stock recruitment. Our study highlights the importance of system-level studies to document and understand the subtleties of how food webs of oligotrophic regions respond to climate change, which may not be predictable from the acquired knowledge of historical studies.

南蓝鳍金枪鱼（SBT, Thunnus maccoyii）广泛分布在南半球丰富的摄食区，但只在印度尼西亚通流直接下游的澳大利亚西北部的一小片热带地区产卵。在这里，我们描述了在SBT产卵高峰期（2022年1月至3月）进行的端到端过程研究的目标、物理环境、设计和主要发现，以了解营养来源、生产力、远洋食物网结构及其与幼虫SBT摄食、生长和生存的关系。中尺度变化是通过连续的地表水测量和沿巡航路线的站点采样来研究的。在Argo盆地南部进行了4次多天拉格朗日实验，确定了生物地球化学和群落关系、过程速率和营养相互作用。研究表明，氮通量、浮游植物生产、放牧过程和出口之间存在强大的系统平衡。对尾尾虫的高度选择性取食可以有效地从浮游植物为主的生产向SBT幼虫转移营养。与墨西哥湾大西洋蓝鳍金枪鱼幼虫栖息地的类似测量结果相比，浮游生物生产力、浮游植物碳和浮游动物生物量按比例升高，但沿海边缘的平流输入较少。基于个体的耳石和稳定同位素分析表明，低营养地位、狭窄饮食和狭窄母亲饮食的幼虫生长最快，最有可能促进种群补充。我们的研究强调了系统级研究的重要性，以记录和理解营养不良地区食物网如何响应气候变化的微妙之处，这可能无法从历史研究中获得的知识来预测。

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引用次数: 0