Marine Micropaleontology最新文献_第7页

Controls on barium incorporation into tests of benthic foraminifera from the Aegean Sea (Eastern Mediterranean Sea) – Towards a species-specific Ba/Ca calibration 爱琴海（东地中海）底栖有孔虫试验中钡掺入的控制。针对特定物种的Ba/Ca校准

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-01-01 DOI: 10.1016/j.marmicro.2024.102431

Jassin Petersen , Gerhard Schmiedl , Jacek Raddatz , André Bahr , Jörg Pross , Meryem Mojtahid

We have analysed Ba/Ca ratios of live and dead benthic foraminifera (Uvigerina mediterranea and Melonis affinis) from core tops of seven sites located in the Aegean Sea by laser ablation ICP-MS. There are no significant Ba/Ca differences in live and dead specimens of U. mediterranea. For M. affinis we apply a threshold criterion for extremely high Ba/Ca in live specimens in order to highlight the overall uniform Ba/Ca signal. The Ba/Ca intra-test variability varies between 16 and 24 % relative standard deviation per specimen. It is attributed to biomineralisation processes i.e., vital effects. The Ba/Ca ratios of M. affinis are significantly higher than those of U. mediterranea throughout most of the sites and their respective samples from different sediment depths. The influence on Ba/Ca of both species by biomineralisation processes and/or microhabitat effects remains open. Linking the Ba/Ca ratios to measured Ba concentration of bottom waters from one of the studied sites, shows partition coefficients of D_Ba = 0.34, and D_Ba = 0.49 for U. mediterranea and M. affinis, respectively. We could not identify trends of Ba/Ca ratios to observed/ modelled gradients of relevant environmental factors between the seven analysed sites, such as primary productivity and associated C_org fluxes or TOC concentrations. Despite the demonstrated limited proxy potential in these parts of the Aegean Sea, we suggest that it is possible to employ Ba/Ca of infaunal benthic species in order to reconstruct export productivity in deep-sea areas with a less complex linkage between primary productivity and nutrient distribution in bottom waters.

我们用激光烧蚀ICP-MS分析了爱琴海7个地点岩心顶部活底栖有孔虫（地中海Uvigerina mediterranea和Melonis affinis）的Ba/Ca比值。在活的和死的地中海鳗标本中Ba/Ca没有显著的差异。对于M. affinis，我们应用了活标本中极高Ba/Ca的阈值标准，以突出整体均匀的Ba/Ca信号。Ba/Ca测试内变异性在每个样品的相对标准偏差为16%至24%之间变化。它归因于生物矿化过程，即生命效应。在大多数地点和不同沉积物深度的样品中，affinis的Ba/Ca比值显著高于U. mediterranea。生物矿化过程和/或微生境效应对两种物种Ba/Ca的影响尚不明确。将其中一个研究地点的Ba/Ca比率与底部水域测量的Ba浓度联系起来，显示地中海和affinis的分配系数分别为DBa = 0.34和DBa = 0.49。我们无法确定七个分析地点之间Ba/Ca比率与观测/模拟的相关环境因子梯度的趋势，例如初级生产力和相关的碳通量或TOC浓度。尽管在爱琴海这些地区的替代潜力有限，但我们认为，在初级生产力与海底营养分布之间的联系不那么复杂的情况下，有可能利用动物底栖生物物种的Ba/Ca来重建深海地区的出口生产力。

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引用次数: 0

Evolutionary, paleoecological and taphonomic aspects of new agglutinated foraminifer Devonodendron scopulum from the Frasnian of Holy Cross Mts, Poland 波兰圣十字山Frasnian新凝集有孔虫Devonodendron scopulum的进化、古生态和地语学方面

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-12-22 DOI: 10.1016/j.marmicro.2024.102434

Grzegorz Racki

Regularly bifurcated tubiform (tree-like) microfossils, although illustrated three decades ago from the Frasnian of the Holy Cross Mts (southern Poland), have not been studied in detail until now. In this paper, the distinctive microproblematic is interpreted as a calcite-cemented agglutinated foraminifer belonging to Devonodendron scopulum sp. et gen. nov., appearing in a major radiation after the Givetian Revolution. Based on the study of isolated three-dimensional specimens, this Devonian species is the best documented of the early branching foraminifera. It resembles living arborescent representatives of the family Schizamminidae (such as Schizammina arborescens and S. andamana), but also the family Dendrophryidae (Psammatodendron arborescens), which has already been reported in the fossil record (Cretaceous; questionable Silurian). However, in light of genetic studies of modern monothalamids, phylogenetic inferences based on such simple morphology are risky. The tree-like branching system of this species suggests erect attached and filter feeding life habit. Devonodendron scopulum shows a pronounced microhabitat selectivity, being dominantly restricted to mid-slope metazoan-microbial mud-mounds. The buildups provided microniches for flourishing a very abundant and diverse calcareous microbiota, including taxa with known (Nanicella) and presumed (Eifeliflabellum) foraminiferal affinities. The environment was characterized by a specific diagenetic setting for the fossilization of micritic-organic tubular tests due to rapid microbially mediated lithification and overwhelming recrystallization processes. As a result, microfossils are largely preserved as stacked homogeneous rhomboidal calcite plates. Many specimens in some sites are actually just coalesced sparry calcite ‘pseudomorphs’ mimicking the original test morphology.

规律分叉的管状（树状）微化石，虽然在三十年前从圣十字山（波兰南部）的弗拉斯尼安发现，但直到现在还没有被详细研究过。在本文中，这一独特的微问题被解释为一种方解石胶结的有孔虫，属于Devonodendron scopulum sp. et gen. 11 .，出现在Givetian革命后的一次主要辐射中。基于对孤立的三维标本的研究，这个泥盆纪物种是早期分支有孔虫中记录最好的物种。它类似于Schizamminidae科（如Schizammina arborescens和S. andamana）的现存乔木代表，但也类似于已经在化石记录中报道的树科（Psammatodendron arborescens）。可疑的志留纪)。然而，鉴于现代单丘脑的遗传研究，基于这种简单形态的系统发育推断是有风险的。该物种的树状分支系统表明直立附着和滤食的生活习惯。泥盆子具有明显的微生境选择性，主要局限于中坡后生动物-微生物泥丘。这些积累为丰富多样的钙质微生物群提供了微生态环境，包括已知的（Nanicella）和推定的（Eifeliflabellum）有孔虫类群。由于快速的微生物介导的岩化作用和压倒性的再结晶过程，该环境的特点是为微晶有机管状试验的石化提供了特定的成岩环境。因此，微化石大部分以堆积均匀的菱形方解石板的形式保存下来。在一些地点的许多标本实际上只是合并的亮晶方解石“假晶”，模仿原始的测试形态。

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引用次数: 0

Eocene to Early Miocene dinoflagellate cysts from the southern Gulf of Mexico 墨西哥湾南部始新世至中新世早期的鞭毛藻囊肿

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-12-01 DOI: 10.1016/j.marmicro.2024.102422

Alessandro-Cesare Bruno, Javier Helenes

This paper documents the Eocene to Miocene dinoflagellate cyst assemblages found at Site 94 in the southern part of the Gulf of Mexico. Four unique dinoflagellate cyst assemblages representing depositional periods from the Early Eocene to the Early Miocene are defined in this study. The Early to Middle Eocene assemblage presents the highest average concentrations of dinoflagellate cysts, is dominated by Operculodinium, and contains few heterotrophic taxa. The Early Oligocene assemblage has medium concentration and is dominated by Deflandrea. The Late Oligocene also has high average concentrations of dinoflagellate cysts, is dominated by Homotryblium, and contains few heterotrophic taxa. The Early Miocene assemblage has lower average concentrations of dinoflagellate cysts, is dominated by Pyxidinopsis, and lacks heterotrophic taxa. Our palynological data is related to significant regional paleogeographic and paleoceanographic changes. Namely, the Early to Middle Eocene free flow of tropical water masses from the south and the Late Eocene restriction of this flow by a land bridge connecting northern South America to Cuba in the north. The Oligocene gradual return of the tropical water masses and finally, the Early Miocene emergence of the Florida Platform when the Gulf of Mexico reached modern oceanographic conditions. The stratigraphic ranges of selected dinoflagellate cysts fit in age with previous microfossil data from the site and allowed us to define the Early Oligocene - Late Oligocene transition. The presence of well-preserved dinoflagellate cysts allowed the identification of 60 species and the discovery of three new species: Achomosphaera psilata sp. nov., Carpatella reticulata sp. nov., and Hystrichosphaeropsis gulficum sp. nov.

本文记录了墨西哥湾南部94号遗址发现的始新世至中新世鞭毛藻囊群。本研究确定了四个独特的鞭毛藻囊组合，代表了早始新世至早中新世的沉积时期。早至中始新世组合中鞭毛藻包囊平均浓度最高，以包鞭毛藻为主，异养类群较少。早渐新世组合浓度中等，以偏陆系为主。晚渐新世也有高平均浓度的鞭毛藻囊，以同鞭毛藻为主，异养类群较少。早中新世组合中鞭毛藻囊的平均浓度较低，以Pyxidinopsis为主，缺乏异养分类群。我们的孢粉学数据与显著的区域古地理和古海洋变化有关。即，早始新世至中始新世热带水团从南部自由流动，晚始新世由连接南美洲北部和古巴北部的陆桥限制这种流动。渐新世热带水团逐渐回归，最终，早中新世佛罗里达台地出现，墨西哥湾达到现代海洋条件。所选择的鞭毛藻囊的地层范围与该地点先前的微化石数据相吻合，使我们能够确定早渐新世-晚渐新世的过渡。保存完好的鞭毛藻包囊鉴定了60个物种，并发现了3个新种：Achomosphaera psilata sp. nov.、Carpatella reticulata sp. nov.和Hystrichosphaeropsis gulficum sp. nov.。

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引用次数: 0

Unraveling the palaeoecology of Paralia sulcata-dominated assemblages from Late Miocene marine deposits of Patagonia (South Atlantic, Argentina) 巴塔哥尼亚（阿根廷南大西洋）晚中新世海相沉积中以Paralia sulcata为主的集合体的古生态学研究

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-11-21 DOI: 10.1016/j.marmicro.2024.102421

Aylén Allende Mosquera , Rocío Fayó , Camilo Andrés Vélez-Agudelo , Marcela Alcira Espinosa , José Ignacio Cuitiño

The study of fossil diatom assemblages constitutes an effective tool for inferring past water conditions. Several studies from around the world suggest the Miocene was a key period in the evolutionary history of diatoms. However, Miocene diatom assemblages from the southwestern Atlantic Ocean are nearly unknown. This study aims to provide a palaeoenvironmental interpretation of the analysed succession. Additionally, to highlight temporal and regional changes, the assemblage is compared with known modern and fossil assemblages from Patagonia and other regions of the world. Finally, we provide a detailed description of the extinct diatom taxa recognised throughout the sedimentary succession. A total of 36 diatom taxa were recognised in the 25 analysed samples. Despite the evidence from sedimentology and macro-palaeontology indicating temporal changes from inner shelf to estuarine environments, the diatom assemblages are dominated by the coastal marine Paralia sulcata sensu lato throughout the succession. An important freshwater input into the coastal system is interpreted from our results reflecting more humid climatic conditions when compared with modern diatom assemblages from the same location. In addition, four extinct species were recognised: Thalassiosira cf. yabei, Pseudopodosira westii, Rhaphoneis diamantella, and Lancineis rectilatus. The presence of R. diamantella and L. rectilatus in the analysed deposits would imply an expansion of their geological range.

硅藻化石组合研究是推断过去水体状况的有效工具。世界各地的一些研究表明，中新世是硅藻进化史上的一个关键时期。然而，大西洋西南部的中新世硅藻群几乎无人知晓。本研究旨在对所分析的演替进行古环境解释。此外，为了突出时间和区域变化，我们还将该组合与巴塔哥尼亚和世界其他地区的已知现代和化石组合进行了比较。最后，我们对整个沉积演替中已灭绝的硅藻类群进行了详细描述。在分析的 25 个样本中，共确认了 36 个硅藻类群。尽管沉积学和大型古生物学的证据表明，从内陆架到河口环境发生了时间变化，但在整个演替过程中，硅藻群仍以近岸海洋硅藻（Paralia sulcata sensu lato）为主。与同一地点的现代硅藻群相比，我们的研究结果反映了更潮湿的气候条件，从而解释了淡水对沿岸系统的重要输入。此外，我们还发现了四个已灭绝的物种：Thalassiosira cf. yabei、Pseudopodosira westii、Rhaphoneis diamantella 和 Lancineis rectilatus。R. diamantella 和 L. rectilatus 出现在分析的沉积物中，这意味着它们的地质分布范围有所扩大。

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引用次数: 0

Ocean gateways and circulation dynamics: Unveiling the deep water-mass properties in the western equatorial Pacific since the Middle Miocene 海洋门户和环流动力学：揭示中新世以来西赤道太平洋的深层水团特性

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-11-20 DOI: 10.1016/j.marmicro.2024.102420

Himanshu Bali, Anil K. Gupta

Tectonically driven adjustments in the ocean gateways, such as the constriction and closure of the Central American Seaway (CAS), have been linked to the significant variations in deep water circulations across the Atlantic and Pacific Oceans in the Miocene. The changes in these tectonic gateways had substantial consequences on the Atlantic Meridional Overturning Circulation (AMOC), the Antarctic Circumpolar Current (ACC) and consequently Antarctic ice sheet growth, and deep water circulation pathways across the ocean basins. The timing of the closure of the deep water connection between the Atlantic and Pacific Oceans, through CAS, and related changes in deep water circulation in the western Pacific are still debatable. We examined foraminiferal relative abundances of epibenthic genus Cibicidoides (a synonym of Cibicides) and its stable isotopic ratios to decipher the timing of tectonically controlled changes in deep water circulation since the Middle Miocene at ODP Site 807, western equatorial Pacific. Our findings, correlated with previously published data, suggest the North Component Water (NCW) incursion from the Atlantic to the western Pacific (Site 807) via CAS between ∼12.5 and ∼ 9.5 Ma. An abrupt decrease in benthic foraminifer Cibicidoides kullenbergi at ∼9.5 Ma suggests the initiation of a significant shift in the deep water mass, coinciding with the major δ¹³C divergence between the Atlantic and Pacific oceans.

中新世时期大西洋和太平洋深水环流的显著变化与构造驱动的海洋通道调整有关，如中美洲海道（CAS）的收缩和关闭。这些构造通道的变化对大西洋经向翻转环流（AMOC）、南极环极洋流（ACC）产生了重大影响，从而导致了南极冰盖的增长，并影响了整个大洋盆地的深水环流路径。通过南极环流关闭大西洋和太平洋之间深水联系的时间以及西太平洋深水环流的相关变化仍有争议。我们研究了赤道西太平洋 ODP 807 号地点有孔虫属 Cibicidoides（Cibicides 的异名）的有孔虫相对丰度及其稳定同位素比值，以破译中新世以来受构造控制的深水环流变化的时间。我们的研究结果与之前公布的数据相关，表明北成分水（NCW）在 12.5 至 9.5 马年之间通过中科院从大西洋侵入西太平洋（807 号站点）。底栖有孔虫 Cibicidoides kullenbergi 在 9.5 Ma ∼突然减少，表明深海水团开始发生重大转变，与大西洋和太平洋之间的主要 δ13C 分异相吻合。

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引用次数: 0

Bashkirian-Moscovian (Lower–Middle Pennsylvanian) conodonts from the Amazonas Basin, northern Brazil: Biostratigraphy, biofacies, and paleobiogeographic significance for Western Gondwana 来自巴西北部亚马孙盆地的巴什基尔-莫斯科（下-中-宾夕法尼亚）锥齿轮动物：生物地层学、生物构成以及对西冈瓦纳古生物地理的意义

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-09-01 DOI: 10.1016/j.marmicro.2024.102407

Martín A. León-Caffroni , Ana K. Scomazzon , Tamara I. Nemyrovska , Sara Nascimento , Andrés F.R. Mantilla , Sanmya K.R. Dias , Amanda P. da Rosa , Jordana M. Viccari , Paulo A. Souza , Valesca B. Lemos

Bashkirian-Moscovian (Lower to Middle Pennsylvanian) Itaituba Formation is well exposed in the Itacimpasa Quarry at the southern platform of the Amazonas Basin, northern Brazil. An abundant and diverse conodont fauna was recovered from this predominantly carbonate formation, with a total of 19 species belonging to 8 genera identified. The following species were documented and systematically described for the first time in the basin: Declinognathodus marginodosus, Declinognathodus donetzianus, Idiognathoides postsulcatus, Idiognathoides fossatus, Diplognathodus benderi, Adetognathus spathus, and Idioprioniodus conjunctus, providing significant stratigraphic and environmental insights into the Bashkirian-Moscovian boundary (BMB) interval. The Declinognathodus marginodosus – Neognathodus atokaensis (upper Bashkirian Stage) and the Declinognathodus donetzianus – Diplognathodus ellesmerensis (lower Moscovian Stage) zones are recognized. The distribution of conodonts studied through cluster analysis reveals the conodont biofacies Idiognathodus/Adetognathus and Declinognathodus/Idiognathoides biofacies. Changes in these conodont biofacies are interpreted as the result of a marine ingression event in Western Gondwana during the BMB interval. The fauna recorded in the studied section shows affinities with conodont faunas reported from Paleo-Tethys Ocean regions indicating a faunal connection of this ocean with the Panthalassa in Western Gondwana. These findings contribute significantly to the refinement of the biostratigraphy and paleobiogeography of the Bashkirian-Moscovian boundary interval in the Amazonas Basin and Western Gondwana.

巴什基尔-莫斯科（下至中宾夕法尼亚）期的伊塔图巴地层出露于巴西北部亚马孙盆地南部平台的伊塔辛帕萨采石场（Itacimpasa Quarry）。在这个以碳酸盐岩为主的地层中发现了丰富多样的锥齿动物群，共鉴定出 8 个属 19 个物种。首次在该盆地记录并系统描述了以下物种：其中包括：Declinognathodus marginodosus、Declinognathodus donetzianus、Idiognathoides postsulcatus、Idiognathoides fossatus、Diplognathodus benderi、Adetognathus spathus 和 Idioprioniodus conjunctus，为巴什基尔-莫斯科边界（BMB）区间提供了重要的地层和环境信息。研究发现了Declinognathodus marginodosus - Neognathodus atokaensis（上巴什基尔期）和Declinognathodus donetzianus - Diplognathodus ellesmerensis（下莫斯科期）区。通过聚类分析研究的锥齿动物分布揭示了 Idiognathodus/Adetognathus 和 Declinognathodus/Idiognathoides 锥齿动物生物成因。这些锥齿动物生物群落的变化被解释为 BMB 区间西冈瓦纳海侵事件的结果。研究区段记录的动物群与古特提斯洋地区报告的圆锥体动物群有亲缘关系，表明该洋与冈瓦纳西部的 Panthalassa 动物群有联系。这些发现对完善亚马孙盆地和西冈瓦纳地区巴什基尔-莫斯科边界区间的生物地层学和古生物地理学有重要贡献。

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引用次数: 0

Calcareous Nannofossil variability controlled by Milankovitch and sub-Milankovitch periodicity in the Monte San Nicola section (Gelasian GSSP / MIS 100–104) 受米兰科维奇和亚米兰科维奇周期性控制的蒙特圣尼古拉剖面（格拉西GSSP / MIS 100-104）钙质化石的可变性

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-09-01 DOI: 10.1016/j.marmicro.2024.102397

Sergio Bonomo , Elena Zanola , Alessandro Incarbona , Agata Di Stefano , Salvatore Distefano , Viviana Barbagallo , Patrizia Ferretti , Eliana Fornaciari , Patrizia Macrì , Isabella Raffi , Nadia Sabatino , Fabio Speranza , Mario Sprovieri , Enrico Di Stefano , Rodolfo Sprovieri , Domenico Rio , Luca Capraro

The Quaternary marks the beginning of the ice ages, with the establishment of a stable Northern Hemisphere ice sheet. The Monte San Nicola section, southern Sicily (Italy) is the Global Boundary Stratotype Section and Point of the Gelasian Stage of the Lower Quaternary Subseries and is attracting new attention for providing valuable information on paleoclimate evolution.

Here we present a paleoenvironmental reconstruction based on new data from calcareous nannoplankton, the phytoplankton organisms that are sensitive to sea surface changes and water column dynamics. We adopt statistical and signal analysis to support our paleoenvironmental model. The most evident paleoenvironmental signal throughout the investigated interval is the contrast between the abundance patterns of placoliths and Florisphaera profunda, the former pointing to surface productivity (water column mixing, shallow nutricline), the latter to the establishment of a deep nutricline. The observed nutricline depth shift occurred with a regular precessional pace, following Northern Hemisphere summer insolation and, likely, North African monsoon activity. A significant periodicity of 8 kyr, in tune with late Quaternary Heinrich events, is also observed in nannoplankton taxa, supporting previous findings on the existence of suborbital climatic variability even at the Pliocene-Pleistocene transition.

随着稳定的北半球冰盖的形成，第四纪标志着冰期的开始。意大利西西里岛南部的蒙特圣尼古拉剖面是全球边界地层原型剖面，也是下第四纪子序列格拉西期的起点，因其提供了古气候演变的宝贵信息而受到新的关注。在此，我们根据钙质annoplankton（对海面变化和水柱动力学敏感的浮游植物）的新数据，提出了一种古环境重建方法。我们采用统计和信号分析来支持我们的古环境模型。在整个调查区间内，最明显的古环境信号是块石和深海花叶石藻丰度模式之间的对比，前者表明了表层生产力（水柱混合、浅营养线），后者表明了深营养线的建立。所观测到的营养线深度变化是随着北半球夏季日照和北非季风活动的变化而有规律地发生的。在浮游动物类群中也观察到了与第四纪晚期海因里希事件相一致的 8 千年的重要周期性，这支持了之前关于即使在上新世-更新世过渡时期也存在亚轨道气候多变性的发现。

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引用次数: 0

Analysis of the latitudinal and longitudinal (coastal and pelagic zones) variability of coccolithophore assemblages in the water column of the Western Iberian Margin in late summer of 2022 2022 年夏末伊比利亚西部边缘水体中藻类组合的纬度和经度（沿岸和中上层）变化分析

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-09-01 DOI: 10.1016/j.marmicro.2024.102398

María González-Martín , Andrés S. Rigual-Hernández , Emilia Salgueiro , Fátima Abrantes , José A. Flores

This study investigates the abundance, composition, and biogeographical distribution of coccolithophores in the water column of the northwestern Iberian coastal upwelling system during late summer 2022. Coccolithophore data were compared with in situ measurements of physical, chemical, and biological parameters, as well as with satellite data and the upwelling index (UI) for the study area. Canonical Correspondence Analysis (CCA) was performed to determine the relationships between coccolithophore assemblages and environmental variables. The results reveal a latitudinal and longitudinal gradient in coccolithophore abundance, with higher concentrations towards the north and east, indicating a stronger influence of coastal upwelling near the coast (stations CA-7, CA-8, CA-4). Our data suggest that the source of upwelled water in the north (Eastern North Atlantic Central Waters of subpolar origin, ENACWsp) differs from that in the south (ENACWst, of subtropical origin). Significant correlations between UI and the total abundance of coccoliths and coccospheres underscore the role of upwelling in coccolithophore distribution. Additionally, correlations with fluorescence and turbidity indicate that coccolithophores contribute substantially to primary production in the region. Certain species are proposed as paleoenvironmental indicators due to their affinity for specific environmental conditions. The small Noëlaerhabdaceae group (small Gephyrocapsa group + Emiliania huxleyi) serves as a proxy for primary productivity and intense upwelling, while Florisphaera profunda is associated with upwelling relaxation and low productivity. Discrepancies with satellite data are attributed to their limitations in detecting subsurface biological processes. This study also supports the use of the N-ratio in water column samples, not just in sediments, and improves the understanding of primary productivity at the Western Iberian Margin during the upwelling season.

本研究调查了 2022 年夏末伊比利亚西北部沿岸上升流系统水体中嗜茧石藻的丰度、组成和生物地理分布。嗜球藻数据与物理、化学和生物参数的现场测量数据以及研究区域的卫星数据和上升流指数（UI）进行了比较。进行了典型对应分析（CCA），以确定藻胶体组合与环境变量之间的关系。结果表明，茧石藻类丰度存在纬度和纵向梯度，向北和向东集中度较高，表明海岸附近（CA-7、CA-8、CA-4 站）受沿岸上升流的影响较大。我们的数据表明，北部（亚极地起源的北大西洋东部中央水域，ENACWsp）的上升流水源与南部（亚热带起源的北大西洋东部中央水域，ENACWst）的上升流水源不同。UI与茧石和茧球的总丰度之间的显著相关性突出表明了上升流在嗜茧生物分布中的作用。此外，与荧光和浊度的相关性表明，嗜茧生物对该地区的初级生产有很大贡献。某些物种因其与特定环境条件的亲和性而被认为是古环境指标。小型 Noëlaerhabdaceae 组（小型 Gephyrocapsa 组 + Emiliania huxleyi）是初级生产力和强烈上升流的代表，而 Florisphaera profunda 则与上升流松弛和低生产力有关。与卫星数据的差异归因于其在探测表层下生物过程方面的局限性。这项研究还支持在水体样本（而不仅仅是沉积物）中使用 N-比率，并提高了对西伊比利亚边缘地区上升流季节初级生产力的认识。

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引用次数: 0

Benthic foraminifera biomass on the continental slope and São Paulo plateau of Santos Basin (SE Brazil): Comparison of different estimation methods 桑托斯盆地（巴西东南部）大陆坡和圣保罗高原的底栖有孔虫生物量：不同估算方法的比较

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-09-01 DOI: 10.1016/j.marmicro.2024.102396

Amanda Vilar , Thaisa Marques Vicente , Maria Virginia Alves Martins , Silvia Helena de Mello e Sousa

The biomass of benthic foraminifera stands out in marine environments compared to other meiofaunal organisms. Estimating the biomass of these organisms is a valuable biotic descriptor for understanding the carbon cycle and the flow of particulate organic matter. This study estimates the biomass of benthic foraminifera on the slope and plateau of the Santos Basin (SE Brazil) using the biovolume and cytoplasmic occupancy methodology. This work applies a non-destructive biovolume method of estimating biomass by the direct visualization of cytoplasmic occupancy (DV) compared with pre-established (in the literature) percentages of cytoplasmic occupation of the test volume: an average of 32 % (GE) and 35 % (AL). Although there was no statistically significant difference (p < 0.05) between DV and cytoplasmic percentages, it is recognized that the calculation of GE and AL can bias the results. We, therefore, emphasize the need to assess biomass according to species composition and ultrastructural variability. The species with the biggest individuals (>250 μm) contributed most to biomass in the Santos Basin and are considered k-strategists. In contrast, the species with smaller specimens (250–63 μm) are considered r-strategists, contributing more to the density in the study area. This study highlights the discrepancy between the abundant species biomass results by measuring all specimens and the extrapolation of the population for less sample effort, probably due to biological (e.g. intra/inter species variations) and environmental (e.g. availability of food and oxygen) factors. Based on the ecology of the species, the biomass estimates seem to reveal a relationship with the quantity and quality of organic matter, which will be investigated in the future. Future studies should consider the internal structures and address potential errors resulting from cytoplasm dehydration when staining and drying are performed.

与其他小型底栖生物相比，底栖有孔虫的生物量在海洋环境中尤为突出。估算这些生物的生物量是了解碳循环和微粒有机物流的重要生物描述指标。本研究采用生物体积和细胞质占位法估算了桑托斯盆地（巴西东南部）斜坡和高原底栖有孔虫的生物量。这项研究采用非破坏性生物体积法，通过直接观察细胞质占据率（DV）与预先确定的（文献中的）测试体积细胞质占据率（平均为 32%（GE）和 35%（AL））进行比较，来估算生物量。虽然 DV 和细胞质百分比之间没有统计学意义上的显著差异（p < 0.05），但我们认识到，GE 和 AL 的计算可能会使结果出现偏差。因此，我们强调需要根据物种组成和超微结构变异来评估生物量。在桑托斯盆地，个体最大（250 μm）的物种对生物量的贡献最大，被认为是k-战略家。与此相反，个体较小（250-63 μm）的物种被认为是 r 型策略者，对研究区域的密度贡献较大。这项研究凸显了通过测量所有标本得出的丰富物种生物量结果与通过较少取样工作得出的种群推断结果之间的差异，这可能是由于生物（如物种内/物种间的差异）和环境（如食物和氧气的可用性）因素造成的。根据物种生态学，生物量估计值似乎揭示了与有机物的数量和质量之间的关系，今后将对此进行研究。未来的研究应考虑内部结构，并解决染色和干燥时细胞质脱水可能造成的误差。

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Using foraminifera to assess changes in marine coastal habitats of Caribbean Panama since the Middle Holocene 利用有孔虫评估中全新世以来巴拿马加勒比海沿海生境的变化

IF 1.5 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2024-09-01 DOI: 10.1016/j.marmicro.2024.102408

Maria N. Gudnitz , Laurel S. Collins

Humans settled the Bocas del Toro archipelago of Caribbean Panama ∼690 CE. Coastal land was cleared for agriculture in the late 1880s and in recent decades water quality degradation has been detected. To investigate changes that support a decline in water quality and to assess differences in salinity caused by increased runoff from cleared lands, benthic foraminifera of Almirante Bay served as an environmental proxy to compare modern and Middle Holocene times. The foraminiferal community structure of 17 modern mangrove, seagrass, and coral reef habitats <2 m deep was analyzed in combination with 18 samples of ∼6600-year-old coral reef, seagrass and muddy molluscan biofacies from Isla Colón island.

The foraminiferal communities' species and diversity overlap considerably among habitats of both ages, and there is more difference in species' proportions between the ages than among habitats of either age. These patterns reflect high connectivity across adjacent habitats in this embayed, patch-reef setting. Assemblages from Middle Holocene molluscan muds and modern mangroves are least diverse, fairly similar, and well differentiated from those of seagrass and coral habitats. Foraminiferal wall structure suggests more freshwater input in modern times, consistent with forest clear-cutting for agriculture, although both ages fall within the low end of normal salinity. Increased freshwater input influenced assemblage changes but they were not sufficient to reduce measured diversity. Reported declines in the bay's water quality have also not resulted in net foraminiferal diversity loss from ∼6600 years ago, indicating substantial resilience in these extremely shallow, tropical coastal communities.

公元前 690 年，人类在巴拿马加勒比海的博卡斯德尔托罗群岛定居。19 世纪 80 年代末，沿海土地被开垦为农业用地，近几十年来发现水质有所下降。为了研究支持水质下降的变化，并评估因开垦地径流增加而造成的盐度差异，阿尔米兰特湾的底栖有孔虫作为环境替代物，用于比较现代和中全新世时期。有孔虫群落的物种和多样性在两个时代的栖息地之间有相当大的重叠，不同时代之间物种比例的差异比任何一个时代的栖息地之间的差异都大。这些模式反映了在这种淤积的片礁环境中，相邻栖息地之间的高度连通性。来自中全新世软体动物淤泥和现代红树林的组合物的多样性最少，与海草和珊瑚栖息地的组合物相当相似，且差异较大。有孔虫壁结构表明，现代有更多的淡水输入，这与为农业而砍伐森林是一致的，尽管这两个时代都属于正常盐度的低端。淡水输入的增加影响了生物群落的变化，但不足以减少测量到的多样性。据报道，海湾水质的下降也没有导致有孔虫多样性的净损失，这表明这些极浅的热带沿岸群落具有很强的恢复能力。

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引用次数: 0