北冰洋西部赫歇尔盆地近期环境变化的微区系记录

IF 0.9 4区 地球科学 Q4 PALEONTOLOGY
J. Falardeau, A. de Vernal, M. Seidenkrantz, T. Cronin, L. Gemery, Léo Chassiot, M. Fritz, Vladislav Carnero-Bravo, C. Hillaire‐Marcel, P. Archambault
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引用次数: 2

摘要

从加拿大波弗特海架赫歇尔盆地取回的两个海洋沉积物岩芯中,海底有孔虫、介形虫和丁虫的微动物组合记录了与盐度、海冰覆盖和湍流等环境参数的关系。岩心YC18-HB-GC01和PG2303-1分别在水深18米和32米处采集。在这些地点,沉积物堆积率在0.6至1.7 cm yr-1之间,在过去50年中具有接近年度的时间分辨率。多元分析表明,底栖有孔虫群落主要对食物供应作出反应。两个岩芯的微动物组合之间的差异主要是由于底层水盐度水平与水深有关。底栖有孔虫物种棒形Elphidium clavatum的高丰度和巴氏Elphidiumbartletti的出现表明,YC18-HB-GC01浅芯区的盐度不同,但相对较低,这可能受到夏季盐跃层深度变化的影响。更高的物种多样性和更丰富的肾形Cassidulina reniforme和Feyligi Stainthoria表征了更深的核心PG2303-1,这可能反映了在整个研究时间间隔内更稳定的条件和更高的底层水盐度。在YC18-HB-GC01较浅的较长岩芯中观察到的过去50年中最重要的微型动物迁移发生在21世纪之交。在~2000 CE之前,norcrossi Islandiella的存在表明更稳定的生理盐水条件。自公元2000年以来,海燕草和伞状纤毛虫Tintinnopsis fimbriata的丰度增加表明盐度降低,浊度增加。约2000年CE后,Eoeponidella pulchella的丰度增加,表明在过去二十年中生产力同时提高。这种变化几乎与夏季平均海冰浓度的下降同步,这对陆架底层水的稳定性起着重要作用。偏东风可以减少海冰覆盖,但也会促进麦肯齐河羽流的向西扩散,以及营养丰富的太平洋水域向上涌到大陆架上。这两个因素都可以解释赫歇尔盆地更新和生产力的提高。在过去的二十年里,介形虫的丰度也有所下降,这可能与较高的水浊度有关。这项研究表明,结合海底有孔虫、介形虫和Tintinids的信息,可以全面了解北极近海栖息地最近的水文/气候变化,那里的生产力对当地社区的粮食安全至关重要。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Microfaunal Recording of Recent Environmental Changes in the Herschel Basin, Western Arctic Ocean
Microfaunal assemblages of benthic foraminifera, ostracods, and tintinnids from two marine sediment cores retrieved from the Herschel Basin of the Canadian Beaufort Sea shelf document relationships with environmental parameters such as salinity, sea-ice cover, and turbulence. Cores YC18-HB-GC01 and PG2303-1 were collected at 18 and 32 m water depth, respectively. At these sites, sediment accumulation rates range between 0.6 and 1.7 cm yr–1 allowing a near-annual temporal resolution over the last 50 years. Multivariate analyses indicate that benthic foraminiferal assemblages respond primarily to food supply. Dissimilarities between the microfaunal assemblages of the two cores are mainly the result of bottom water salinity levels linked to water depth. High abundance of the benthic foraminiferal species Elphidium clavatum and occurrences of Elphidium bartletti point to varying, but relatively low, salinities at the shallow core site YC18-HB-GC01, which may be affected by variations in the summer halocline depth. Higher species diversity and more abundant Cassidulina reniforme and Stainforthia feylingi characterize the deeper core PG2303-1, which might reflect more stable conditions and higher bottom-water salinities throughout the studied time interval. The most important microfaunal shift of the last 50 years, observed in the shallower longer core YC18-HB-GC01, occurred at the turn of the 21st century. Prior to ∼2000 CE, the presence of Islandiella norcrossi indicates more stable and saline conditions. Since ∼2000 CE, increased abundances of Haynesina nivea and of the ciliate Tintinnopsis fimbriata suggest decreased salinity and increased turbidity. An increased abundance of Eoeponidella pulchella after ∼2000 CE suggests a concurrent increase in productivity in the last two decades. This shift is nearly synchronous with a decrease in mean summer sea-ice concentration, which can play an important role in bottom water stability on the shelf. Easterly winds can induce a reduction in the sea-ice cover, but also foster a westward spreading of the Mackenzie River plume and the upwelling of nutrient-rich Pacific waters onto the shelf. Both factors would explain the increased freshening and productivity of the Herschel Basin. The last two decades were also marked by a decrease in ostracod abundance that may relate to higher water turbidity. This study shows that combining information from benthic foraminifera, ostracods, and tintinnids provides a comprehensive insight into recent hydrographic/climatic changes in nearshore Arctic habitats, where productivity is critical for the food security of local communities.
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来源期刊
Journal of Foraminiferal Research
Journal of Foraminiferal Research 地学-古生物学
CiteScore
2.10
自引率
9.10%
发文量
32
审稿时长
>12 weeks
期刊介绍: JFR publishes original papers of international interest dealing with the Foraminifera and allied groups of organisms. Review articles are encouraged.
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