Marine Micropaleontology最新文献_第5页

Large-sized benthic foraminifera at the northern limit of subtropical zone: southern Kochi, Shikoku Island, Japan 亚热带北部边界的大型底栖有孔虫：日本四国岛高知南部

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-01 Epub Date: 2025-07-02 DOI: 10.1016/j.marmicro.2025.102489

Bryan Gabriel P. Tan , Kazuhiko Fujita

Large benthic foraminifera (LBF) are relatively large (>0.5 mm), symbiotic with microalgae, and can be found in tropical to subtropical, clear, shallow waters. LBF are commonly studied in lower latitudes but are less studied in higher latitudes close to their current limit of geographic distribution. As climate change progresses, poleward extension is expected to proceed apace, thus it is important to characterize benthic foraminiferal fauna in these higher latitude zones in order to track the progress of their habitat extensions. The present study examined large-sized (0.5 to 2 mm size fraction) benthic foraminifera, both symbiotic and non-symbiotic, in one such region: Kochi Prefecture in Shikoku Island, Japan. Living foraminifera attached to algae as well as in sediment, and dead foraminiferal tests in sediment were collected from three stations in the study area. A total of 64 taxa were identified, of which 17 were found living in algae, 8 living in sediment, and 60 were dead in sediment. Amphistegina lobifera was the dominant species in the region, making up almost 50 % of all specimens identified, followed by other symbiotic foraminifera. Compared to foraminiferal living communities and dead assemblages in lower latitudes (the Ryukyu Island Arc), amphisteginids and textulariids were more common in Kochi. Calcarinids which are dominant in the Ryukyu Island Arc were not found in this study.

大型底栖有孔虫（LBF）相对较大（>0.5 mm），与微藻共生，可在热带至亚热带，清澈，浅水中发现。LBF通常在低纬度地区进行研究，但在接近其当前地理分布极限的高纬度地区研究较少。随着气候变化的进展，极向扩展预计将迅速进行，因此，为了跟踪其栖息地扩展的进展，对这些高纬度地区的底栖有孔虫动物群进行表征是重要的。本研究在日本四国岛的高知县调查了大型（0.5至2毫米大小的部分）底栖有孔虫，包括共生和非共生。在研究区三个站点收集了附着于藻类和沉积物中的活有孔虫，以及沉积物中的死有孔虫试验。共鉴定出64个分类群，其中17个生活在藻类中，8个生活在沉积物中，60个死于沉积物。该地区的优势种为大叶两栖虫，占所有鉴定标本的近50%，其次是其他共生有孔虫。与低纬度地区（琉球岛弧）的有孔虫生活群落和死亡群落相比，高知地区的amphisteginids和textulariids更为常见。本研究未发现琉球岛弧中占优势的Calcarinids。

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引用次数: 0

The genetic isolation of planktonic foraminifera in the North Pacific gyre and adjacent marginal seas 北太平洋环流及其邻近边缘海浮游有孔虫的遗传分离

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-01 Epub Date: 2025-05-21 DOI: 10.1016/j.marmicro.2025.102473

Kate F. Darling , Agnes K.M. Weiner , Atsushi Kurasawa , Takashi Toyofuku , Hiroshi Nishi , Hiroshi Kitazato

Gaining insight into the speciation processes prevailing in the modern open ocean requires a comprehensive understanding of the spatial dynamics of the planktonic species that inhabit it, calibrated against time. The high-resolution fossil record of the planktonic foraminifera not only provides such insight but also plays a crucial role in the study of past climate. Both rely on understanding how species relate to the current physical and ecological character of the oceanic water masses they inhabit. Within global single cell barcoding and metabarcoding studies of planktonic foraminifera, the North Pacific subtropical and subpolar gyres remain under-sampled, with the capacity to harbour unrecognised ecologically distinct cryptic species. Targeting this issue, Globigerina bulloides specimens were collected during 12 cruises and near shore sampling campaigns throughout the Northern Pacific and marginal seas. Using standard molecular approaches, 406 specimens were genetically characterised and combined with 42 publicly available sequences to provide a fully comprehensive overview of G. bulloides diversity throughout the North Pacific. Of ten globally recognised genotypes, six (Ia, Ic, Id, IIa, IId, IIf) inhabit the water masses south of the Subpolar Front, with only a single genotype (IIe) inhabiting the vast Subpolar gyre and marginal seas. Genetic isolation was found to prevail throughout both the western subtropical waters (Types Ic and Id) and subpolar waters (Type IIe) of the North Pacific together with the North and South Pacific eastern boundary currents (Type IId). Unlike the Atlantic, bipolarity does not occur between the North Pacific and the Southern Ocean subpolar/polar pelagic biomes.

要深入了解现代开放海洋中普遍存在的物种形成过程，需要对栖息在其中的浮游生物物种的空间动态有全面的了解，并根据时间进行校准。浮游有孔虫的高分辨率化石记录不仅提供了这样的见解，而且在研究过去的气候中起着至关重要的作用。两者都依赖于了解物种与它们所栖息的海洋水体当前的物理和生态特征之间的关系。在全球浮游有孔虫单细胞条形码和超条形码研究中，北太平洋亚热带和亚极地环流的样本仍然不足，有能力庇护未被识别的生态独特的隐物种。针对这一问题，在整个北太平洋和边缘海域进行了12次巡航和近岸取样活动，收集了球形球虫标本。使用标准的分子方法，对406个标本进行了遗传表征，并与42个公开的序列相结合，以提供整个北太平洋G. bulloides多样性的全面概述。在全球公认的十种基因型中，有六种（Ia、Ic、Id、IIa、IId、IIf）生活在亚极锋以南的水团中，只有一种基因型（IIe）生活在广阔的亚极环流和边缘海域。遗传隔离现象普遍存在于西亚热带水域（Ic型和Id型）和北太平洋亚极地水域（IIe型）以及南北太平洋东部边界流（IId型）。与大西洋不同的是，在北太平洋和南大洋的亚极地/极地远洋生物群系之间不会出现双极性。

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引用次数: 0

Environmental history of northwestern Vancouver Island (British Columbia, Canada) during the Holocene: A high-resolution dinoflagellate cyst record from Kyuquot Sound 加拿大不列颠哥伦比亚省温哥华岛西北部全新世环境史：奎括湾高分辨率鞭毛藻囊记录

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-01 Epub Date: 2025-06-02 DOI: 10.1016/j.marmicro.2025.102475

Pieter R. Gurdebeke , Vera Pospelova , Kenneth N. Mertens , Zhen Li , Bjarn Van Riet , Audrey Dallimore , Stephen Louwye

Environmental changes over the Holocene were reconstructed based on the analysis of dinoflagellate cyst assemblages, their absolute abundances, and morphological changes in Operculodinium centrocarpum sensu Wall & Dale 1966 from 103 sediment samples collected from Core 2012002PGC133 in Tahsish Inlet (Kyuquot Sound), a fjord on the west coast of Vancouver Island (British Columbia, Canada). Eight accelerator mass spectrometry ¹⁴C dates indicate that the record spans the last 12 ka. The cysts are well-preserved, with assemblages displaying high diversity (37 taxa). Six dinoflagellate cyst assemblage zones were identified. Zone I is dominated by Operculodinium centrocarpum sensu Wall & Dale 1966, while subsequent zones (II–IV) are characterized mainly by cysts of heterotrophic species. The uppermost zones (V–VI) show increased abundances of autotrophic taxa. The dinoflagellate cyst record reflects regional and global environmental signals. The dominance of Operculodinium centrocarpum sensu Wall & Dale 1966 during the Younger Dryas corresponds to a lower relative sea level, indicative of marsh-like conditions or proximity to the inlet head at the core site. Increased heterotrophic taxa during the late Early and Middle Holocene suggests a rising marine influence due to RSL rise, possibly enhancing primary productivity through coastal upwelling. Reduced process lengths in Operculodinium centrocarpum sensu Wall & Dale 1966 around ∼8.7 cal kyr BP indicate an abrupt change in local environmental conditions. A sharp increase in absolute cyst abundances ∼2.2 cal kyr BP, primarily driven by Spiniferites spp., is proposed to be linked with climate- and tsunami-related mechanisms.

本文通过对全壳鞭毛藻囊群、绝对丰度和形态变化的分析，重建了全新世的环境变化。从温哥华岛（加拿大不列颠哥伦比亚省）西海岸的一个峡湾tahish Inlet （Kyuquot Sound）收集的103个沉积物样本中提取了Dale 1966。8个加速器质谱14C测年表明该记录跨越了过去12 ka。包囊保存完好，组合多样性高（37个分类群）。发现了6个鞭毛藻包囊聚集带。第I区以中心果壳菌（Operculodinium centrrocarpum sensu Wall）为主；Dale 1966，而随后的区域（II-IV）主要以异养物种的囊肿为特征。最上层（V-VI）自养类群的丰度增加。鞭毛藻囊肿记录反映了区域和全球的环境信号。中心果壳菌的优势性研究新仙女木期的1966谷对应于相对较低的海平面，表明类似沼泽的条件或靠近核心位置的入口头。早全新世晚期和中全新世异养分类群的增加表明，由于RSL上升，海洋的影响增加，可能通过沿海上升流提高初级生产力。缩短了花椒的加工长度；Dale 1966年约8.7 cal kyr BP表明当地环境条件发生了突变。大约2.2 cal kyr BP的绝对囊肿丰度的急剧增加，主要是由Spiniferites spp驱动的，被认为与气候和海啸相关机制有关。

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引用次数: 0

Enhanced sedimentary ancient DNA (sedaDNA) retrieval from Antarctic diatoms 从南极硅藻中增强沉积古DNA （sedaDNA）检索

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-01 Epub Date: 2025-06-07 DOI: 10.1016/j.marmicro.2025.102477

Prashasti Singh , João C. Teixeira , Michael E. Weber , Christopher Bolch , Linda Armbrecht

Diatom microfossils are key environmental indicators and an important proxy in paleoenvironmental reconstructions. Sedimentary ancient DNA (sedaDNA) complements microfossil analysis by detecting poorly preserved diatoms and distinguishing morphologically similar taxa, painting a more detailed picture of the past. However, retrieving diatom sedaDNA in marine environments can be challenging due to trace amounts being preserved in the sediment record. Optimising existing protocols is thus essential to maximise diatom sedaDNA yield. This study compares six methods to determine the best approach for recovering diatom sedaDNA from Antarctic marine sediment cores. The same six samples from two sites - U1536C (West Antarctica) and KC02 (East Antarctica), were extracted. Post shotgun sequencing, the methods were evaluated based on diatom sedaDNA recovery, fragment length, and species diversity. Results showed that method performance in retrieving the highest number of Bacillariophyta (diatom) reads is primarily driven by site (R² = 0.593, p = 0.001) and sample age (R² = 0.401, p = 0.001), while the extraction method had minimal influence (R² = 0.001, p = 0.064). The SiMAG method proved highly effective in U1536C but was entirely ineffective in KC02, where the COM Short method successfully recovered diatom sedaDNA. Other methods, including COM QG, PPKIT, and PB, consistently resulted in low sedaDNA yields. Differences in the diversity and the relative abundance of taxonomic classes were also seen across methods (χ2 88.04 to 99,664.17). This study serves as a focal point for experiments aiming to maximise diatom sedaDNA recovery enabling accurate reconstructions of Antarctic marine ecosystems.

硅藻微化石是古环境重建的关键环境指标和重要代用物。沉积古DNA （sedaDNA）通过检测保存较差的硅藻和区分形态相似的分类群来补充微化石分析，描绘出更详细的过去图景。然而，由于沉积物记录中保存了微量的硅藻sedaDNA，在海洋环境中检索硅藻sedaDNA可能具有挑战性。因此，优化现有方案对于最大限度地提高硅藻sedaDNA产量至关重要。本研究比较了六种方法，以确定从南极海洋沉积物岩心中回收硅藻sedaDNA的最佳方法。从两个地点——U1536C（南极洲西部）和kco2（南极洲东部）——提取了相同的6个样品。霰弹枪测序后，根据硅藻sedaDNA恢复，片段长度和物种多样性对方法进行评估。结果表明，该方法提取硅藻最高reads数主要受位置（R2 = 0.593, p = 0.001）和样品年龄（R2 = 0.401, p = 0.001）的影响，提取方法的影响最小（R2 = 0.001, p = 0.064）。SiMAG方法在U1536C中非常有效，但在kco2中完全无效，其中COM Short方法成功地回收了硅藻sedaDNA。其他方法，包括COM QG、PPKIT和PB，均导致sedaDNA产量较低。不同方法间分类类的多样性和相对丰度也存在差异（χ2 88.04 ~ 99,664.17）。该研究为旨在最大限度地恢复硅藻sedaDNA的实验提供了焦点，从而能够准确重建南极海洋生态系统。

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引用次数: 0

New dinoflagellate cyst species of the Areoligeraceae, Ceratiaceae, Gonyaulacaceae, and Peridiniaceae from the Santonian–Campanian (Upper Cretaceous) of the Nanaimo Group, British Columbia, Canada 加拿大不列颠哥伦比亚省Nanaimo群圣东统-坎帕尼亚统（上白垩统）中Areoligeraceae、Ceratiaceae、Gonyaulacaceae和Peridiniaceae的鞭毛藻囊新种

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-01 Epub Date: 2025-06-13 DOI: 10.1016/j.marmicro.2025.102485

Sandy M.S. McLachlan , Vera Pospelova , James W. Haggart , Kenneth N. Mertens

This is the first study of the late Santonian–early late Campanian dinoflagellate cyst assemblages from the Nanaimo Group strata along eastern Vancouver Island and Denman Island, British Columbia. Four new dinoflagellate cyst species are reported from twenty samples recovered from six localities from the Haslam, Trent River, and Cedar District formations: Alterbidinium? fusiforme sp. nov., Canningia grahamii sp. nov., Nematosphaeropsis snunymuxwensis sp. nov. and Odontochitina kwutlkwuensis sp. nov. Emended diagnoses are proposed for the genera Alterbidinium and Odontochitina, and each of the new species are presented in high resolution scanning electron microscopy images which extend the parameters of morphologies previously recognized as occurring within the families Areoligeraceae, Ceratiaceae, Gonyaulacaceae, and Peridiniaceae. These taxa carry biostratigraphic utility within a temporally constrained interval for the Late Cretaceous toward correlation with other regions in the Northern Hemisphere as well as applications for paleoenvironmental interpretations drawing from their relative and absolute abundances.

本文首次研究了不列颠哥伦比亚省东温哥华岛和登曼岛纳奈莫群地层中晚圣东—晚坎帕尼亚早期鞭毛藻包囊组合。从哈斯拉姆、特伦特河和雪松区地层的6个地点回收的20个样本中，报告了4种新的鞭毛藻囊肿：本文提出了对Alterbidinium属和Odontochitina属的修正诊断，并在高分辨率扫描电镜图像中呈现了每个新种，这些新种扩展了以前在Areoligeraceae， Ceratiaceae， gonyulacaceae和Peridiniaceae中所认识的形态学参数。这些分类群在晚白垩世的时间限制区间内具有生物地层学上的实用性，可以与北半球其他地区进行对比，并可根据其相对丰度和绝对丰度进行古环境解释。

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引用次数: 0

Response of calcareous nannofossils during the danian-thanetian isotopic events in the Elles Section, Central Tunisia 突尼斯中部埃莱斯剖面钙质纳米化石在达旦-达旦-达旦同位素事件中的响应

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-01 Epub Date: 2025-06-28 DOI: 10.1016/j.marmicro.2025.102487

Mahmoud Faris , Sherif Farouk , Fayez Ahmad , Zaineb Elamri , Adel El Shahawy , Fatma Shaker

A high resolution quantitative study of calcareous nannofossils from the Elles section in Central Tunisia (North Africa) was conducted to assess local phytoplankton paleocommunities and infer paleoclimatic conditions. This research introduces a refined subdivision of the conventional NP4 nannofossil zone into six finer intervals (NTp6, NTp7A-B, NTp8A-C), a first for Tunisia, enhancing the biostratigraphic resolution of Paleocene stratigraphy in the region. The assemblages within these subzones exhibit moderate to good preservation and correlate globally with established Tethyan biozonations. Three key isotopic events were identified: The Dan-C2 event, characterized by a negative δ¹³C shift at the base of the NP2 Zone, associated with a significant increase in oligotrophic and warm-water taxa; the Latest Danian Event (LDE), which is divided into Pre- and Post-LDE intervals. The Pre-LDE interval is marked by a short-lived negative δ¹³C excursion within the lowermost part of NTp7A Subzone boundary, accompanied by a notable decline in the diversity and richness of calcareous nannofossils. The third event, the Selandian-Thanetian Transition Event (STTE), occurs at the base of NP7/8 and is biostratigraphically defined by the Lowest Occurrence (LO) of Discoaster mohleri, with a replacement of R-mode taxa by species adapted to warmer, more oligotrophic conditions. The Danian-Selandian transition is clearly delineated by a glauconite-rich hard marl layer (upper NTp8C). This integrated stratigraphic study provides high-resolution biostratigraphy and critical insights into paleoenvironmental changes during this period. The paleoenvironment shifted from warm, oligotrophic conditions during the events to cooler, eutrophic waters both before and after. These findings suggest that the three bioevents may correspond to an early Paleocene hyperthermal episode.

对北非突尼斯中部Elles剖面的钙质纳米化石进行了高分辨率定量研究，以评估当地浮游植物古群落并推断古气候条件。本研究首次将常规NP4纳米化石带精细细分为6个更精细的层段（NTp6、NTp7A-B、NTp8A-C），提高了该地区古新世地层的生物地层分辨率。这些亚带内的组合表现出中度至良好的保存，并与已建立的特提斯生物带具有全球相关性。确定了3个关键同位素事件：Dan-C2事件以NP2带底部负δ13C位移为特征，与贫营养和暖水类群的显著增加有关；最新的大年事件（LDE），分为大年事件前和大年事件后。前lde期段在NTp7A亚带边界最下端出现了短暂的负δ13C偏移，钙质纳米化石的多样性和丰富度明显下降。第三个事件是Selandian-Thanetian Transition event (STTE)，发生在NP7/8的底部，在生物地层学上由disaster mohleri的最低发生率（LO）定义，r型分类群被适应更温暖、更少营养条件的物种取代。富含海绿石的硬泥灰岩层（NTp8C上部）清晰地描绘了达尼安-塞兰地过渡。这一综合地层学研究提供了高分辨率的生物地层学和对这一时期古环境变化的重要见解。在事件发生前后，古环境从温暖的贫营养条件转变为较冷的富营养化水域。这些发现表明，这三个生物事件可能对应于一个早古新世的高温事件。

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引用次数: 0

Extant benthic foraminifera from the Indonesian seas: An update of what we know so far and implications for future studies 印度尼西亚海域现存底栖有孔虫：迄今为止我们所知道的最新情况及其对未来研究的影响

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-05-01 Epub Date: 2025-05-14 DOI: 10.1016/j.marmicro.2025.102471

Sinatrya D. Prayudi , Suhartati M. Natsir , Michael A. Kaminski

To offer a comprehensive understanding of the diversity of benthic foraminifera in the Indonesian seas, we analyzed more than 70 years of datasets from both local and international sources. By reviewing articles covering three major biogeographical regions—Sunda Shelf, Sahul Shelf, and Wallacea—and their varying environmental conditions and depositional environments, we identified a total of 1164 species (including uncertain and genus-level identifications) belonging to 448 genera, 136 families, 14 orders, and four classes, in addition to 1116 genus-level naming (sp. and spp.). Our analysis also revealed 762 instances of taxonomic misnaming, with errors stemming from the use of unaccepted names and confusion between fossils, planktonic, and benthic assemblages. Additionally, most of the reviewed studies were found to be incomplete due to insufficient oceanographic data and a lack of detailed species counts, despite the importance of these factors in such research. This work establishes a robust baseline for future studies and highlights key issues that need to be addressed to avoid repeating past uncertainties and to promote more focused research on benthic foraminifera in the region.

为了全面了解印度尼西亚海域底栖有孔虫的多样性，我们分析了70多年来来自当地和国际来源的数据集。通过对sunda陆架、Sahul陆架和wallea陆架三个主要生物地理区域及其不同的环境条件和沉积环境的文献回顾，我们共鉴定出448属、136科、14目、4纲的1164种（包括不确定和属级鉴定），以及1116种属级命名（sp.和spp.）。我们的分析还揭示了762个分类命名错误的例子，这些错误源于使用不被接受的名称以及化石、浮游生物和底栖生物组合之间的混淆。此外，尽管这些因素在此类研究中很重要，但由于海洋学数据不足和缺乏详细的物种计数，大多数审查的研究发现是不完整的。这项工作为未来的研究奠定了坚实的基础，并强调了需要解决的关键问题，以避免重复过去的不确定性，并促进对该地区底栖有孔虫的更集中的研究。

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引用次数: 0

Early impacts of Arctic amplification in the western North Water Polynya: A 400-year perspective 北极放大对北水峡西部的早期影响：400年的视角

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-05-01 Epub Date: 2025-05-03 DOI: 10.1016/j.marmicro.2025.102470

Kelsey A. Koerner , Audrey Limoges , Emily Pike-Connolly , Nicolas Van Nieuwenhove , André Rochon

The North Water (NOW) polynya in northern Baffin Bay is known for persistent open water, attracting marine mammals and birds during winter. Ice bridges forming north of the NOW at constriction points in Nares Strait aid in sustaining these open water conditions. However, Arctic Amplification has weakened these ice bridges, altering water and sea ice flow into the NOW. We examined the effect of climate warming and recent ice bridge failures through 400 years of changes in the western NOW. We analyzed dinoflagellate cyst (dinocyst) assemblages in a surface sediment transect across the NOW to assess their distribution as indicators of surface water masses. We then analyzed dinocysts and geochemical proxies (carbon and nitrogen signatures) from two sediment cores in the western NOW. Results show the eastern NOW, influenced by the West Greenland Current (WGC), exhibits higher contributions of mixotrophic taxa and total dinocyst concentrations than the western region, influenced by Arctic water outflow. Sediment cores show a 300-year period of stability in the western NOW (1620–1920 CE), followed by an increase in mixotrophic taxa and total dinocyst fluxes, predating observed ice bridge failures. Around 1980 CE, higher abundances of Operculodinium centrocarpum, and cysts of Polarella glacialis and Pentapharsodinium dalei, suggest early sea ice retreat, seemingly attributable to increased WGC influence. These findings demonstrate the early impact of Arctic Amplification on the NOW, with significant changes starting in the first half of the 20th century, which contribute to understanding the timing and propagation of oceanographic changes in the polynya.

巴芬湾北部的北水多冰湖（NOW）以持续开放的水域而闻名，在冬季吸引了海洋哺乳动物和鸟类。现在在Nares海峡的收缩点以北形成的冰桥有助于维持这些开放的水域条件。然而，北极放大削弱了这些冰桥，改变了流入现在的水和海冰。我们通过400年的变化研究了气候变暖和最近冰桥坍塌对西部NOW的影响。我们分析了横跨NOW的表层沉积物样带中的鞭毛藻囊（dinocyst）组合，以评估它们作为地表水质量指标的分布。然后，我们分析了现在西部两个沉积物岩心的生物囊和地球化学指标（碳和氮特征）。结果表明，受西格陵兰洋流影响的东部NOW区混合营养类群和总dinocyst浓度的贡献高于受北极水流影响的西部地区。沉积物岩心显示，现在西部（公元1620-1920年）有300年的稳定期，随后混合营养分类群和总生物囊通量增加，早于观测到的冰桥破坏。1980年前后，Operculodinium centrrocarpum的丰度较高，Polarella glacalis和Pentapharsodinium dalei的囊泡也较高，表明早期海冰退缩，似乎可归因于WGC影响的增加。这些发现证明了北极放大对现在的早期影响，其显著变化始于20世纪上半叶，这有助于理解冰湖海洋变化的时间和传播。

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引用次数: 0

Benthic ostracods as environmental proxies in Nile Delta Coastal Lagoon 尼罗河三角洲沿海泻湖底栖介形类环境指标研究

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-05-01 Epub Date: 2025-04-23 DOI: 10.1016/j.marmicro.2025.102469

Sherif M. El Baz , Abd-ElMonsef A. El-Badry , Pamela Hallock , Ahmed M. BadrElDin

The coastal Nile Delta wetlands are essential in the protection of the cultivated deltaic land against sea level rise and are major resources for biodiversity and fisheries productivity. The Manzala Lagoon ranks highly polluted among the lacustrine coastal environments of the Nile Delta of Egypt. The environmental quality of the lagoon plummeted a few decades ago with the increase in massive quantities of untreated mixed discharges (agricultural, industrial, and municipal). To evaluate the environmental status of the lagoon requires both geochemical analyses and bioindicators. Total organic carbon and concentrations of seven potentially toxic elements (Pb, Cu, Cd, Zn, Ni, Co, Fe) were determined in 25 sediment samples collected during summer 2014, from which three pollution indices were calculated (Contamination Factor, Degree of Contamination, and Pollution Loading Index). In addition, ostracod assemblages were assessed in the very-fine and fine sand-size fractions of the sediments. The lagoonal environment is characterized by low total dissolved solids, abundant organic matter, heavy metal contamination by Pb, Co, Ni, and especially Cd, and low diversity ostracod assemblages. Six fresh- and brackish water ostracod species were documented, but the assemblage was overwhelmingly dominated (>98 %) by stress-tolerant Cyprideis torosa. While this species correlated strongly with total dissolved solids and fine sediment textures, overall, the limited ostracod diversity and dominance of a stress-tolerant species reflects the compromised ecological quality of Manzala Lagoon.

尼罗河三角洲沿海湿地对于保护三角洲耕地免受海平面上升的影响至关重要，也是生物多样性和渔业生产力的主要资源。Manzala泻湖在埃及尼罗河三角洲的湖泊沿岸环境中污染严重。几十年前，随着大量未经处理的混合排放物（农业、工业和市政）的增加，泻湖的环境质量急剧下降。评价泻湖的环境状况需要地球化学分析和生物指标。测定了2014年夏季采集的25份沉积物样品的总有机碳和7种潜在有毒元素（Pb、Cu、Cd、Zn、Ni、Co、Fe）浓度，并计算了污染系数、污染程度和污染负荷指数3个污染指标。此外，在沉积物的极细和细砂级组分中评估介形虫组合。泻湖环境具有总溶解固形物少、有机质丰富、重金属受Pb、Co、Ni、特别是Cd污染、介形虫组合多样性低的特点。记录了6种淡水和半咸水介形类，但该组合绝大多数（> 98%）为耐应力的扁扁螺（cydeis torosa）。虽然该物种与总溶解固体和细沉积物结构密切相关，但总体而言，有限的介形虫多样性和耐应力物种的优势反映了Manzala泻湖生态质量的下降。

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引用次数: 0

Deep-sea benthic foraminifera respond to rapid environmental changes in the central Red Sea during the last glacial period 末次冰期红海中部深海底栖有孔虫对快速环境变化的响应

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-05-01 Epub Date: 2025-05-21 DOI: 10.1016/j.marmicro.2025.102474

Raphaël Hubert-Huard , Yvonne Milker , Gerhard Schmiedl

This study investigates the response of deep-sea benthic foraminifera to changes in food fluxes and dissolved bottom water oxygen in the central Red Sea during the last glacial period (Marine Isotope Stages (MIS) 3 and 4). To assess variations in nutrient intrusion from the Arabian Sea and regional organic matter fluxes, we developed the Red Sea Productivity Index (RSPI) based on changes in sea level and African-Arabian monsoon intensity. We found four distinct species groups, each reflecting different ecological niches and opportunistic behavior. Overall, the fauna of MIS 3 is dominated by the generalist species Bolivina subreticulata, which co-occurs or alternates with other preferentially infaunal taxa of varying opportunistic responses. Changes in the dominance of the different species are primarily controlled by seasonal productivity and associated quantity and quality of available organic matter at the sea floor. This is reflected by a close correspondence of the RSPI and a succession of infaunal species, including Uvigerina juncea s.l., and Bolivina variabilis as the most opportunistic taxa, adapted to strong seasonal food pulses. The succession of the species groups are influenced by millennial-scale changes of the African-Arabian monsoon system and Red Sea deep-water ventilation. This suggests a close link to both low- and high-latitude Northern Hemisphere climate variability. Changes in glacial deep-water oxygenation seem to play an important role during MIS 4, when the dominance of Bolivina persiensis indicates a vertical expansion of the oxygen minimum zone. The high glacial deep-water salinities during sea-level lowstands also fostered the occurrence of miliolid taxa.

本文研究了末次冰期红海中部深海底栖有孔虫对食物通量和溶解氧变化的响应（海洋同位素阶段（MIS） 3和4）。为了评估来自阿拉伯海的养分入侵和区域有机质通量的变化，我们基于海平面和非洲-阿拉伯季风强度的变化建立了红海生产力指数（RSPI）。我们发现了四个不同的物种群体，每个群体都反映了不同的生态位和机会主义行为。总体而言，MIS 3区系以多面手物种Bolivina subreticulata为主，与其他具有不同机会性反应的优先动物类群共存或交替存在。不同物种优势地位的变化主要受季节生产力和海底可利用有机质的相关数量和质量的控制。这反映在RSPI与一系列水生物种的密切对应关系上，包括Uvigerina juncea s.l.和Bolivina variabilis作为最具机会主义的分类群，适应强烈的季节性食物脉冲。物种群的演替受非洲-阿拉伯季风系统的千年尺度变化和红海深水通风的影响。这表明与北半球低纬度和高纬度气候变化有密切联系。冰川深水氧合的变化似乎在MIS 4期间发挥了重要作用，当Bolivina persiensis的优势表明氧最小带的垂直扩展时。在海平面低洼时，高的冰川深水盐度也促进了百万生物类群的发生。

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引用次数: 0