History of the Giraffe Pipe locality inferred from microfossil remains: a thriving freshwater ecosystem near the Arctic Circle during the warm Eocene
History of the Giraffe Pipe locality inferred from microfossil remains: a thriving freshwater ecosystem near the Arctic Circle during the warm Eocene
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DOI：
10.1017/jpa.2022.101
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发表时间：
2023-01-30
影响因子：
1.4
通讯作者：
Lott，Anne Marie
中科院分区：
文献类型：
--
作者：
Siver，Peter A.;Lott，Anne Marie
北极的淡水湖将如何应对气候变化，特别是如果极地放大导致这些北方纬度地区更大的变暖？深时间模拟为了解未来气候变暖对北极环境的潜在影响提供了机会。位于加拿大西北地区的长颈鹿管化石地点的一个核心提供了一个窗口，可以了解始新世温室条件下蓬勃发展的北极淡水生态系统的生活。大量的微化石存款的遗骸，包括光合原生生物（金藻，硅藻，和绿色藻类），异养原生生物（裸藻，日生动物，副单胞菌，和rotosphaerids）和海绵，被用来重建古代水体的历史。金藻类群的浓度和多样性是广泛的整个核心，占70%以上的微体化石遗骸。金藻孢囊与硅藻瓣的比例，在整个岩芯中平均值接近14，进一步强调了金藻的优势地位，并考虑到类群的高度多样性，该地点代表了这一真核生物谱系的“古热点”。根据所有化石证据，长颈鹿烟斗陨石坑内的水体代表了一系列相对较浅的水生栖息地，其物理和化学条件不断变化，水深也各不相同。确定了五个主要区域，每个区域在很长一段时间内都是稳定的，但连续区域之间存在明显的过渡，表明环境条件发生了重大变化。这项研究提供了关于北极淡水生态系统如何应对过去温暖气候的宝贵见解，以及在未来变暖的情况下可能在这些环境中茁壮成长的生物体。
How will freshwater lakes in the Arctic respond to climate change, especially if polar amplification results in even greater warming at these northern latitudes? Deep time analogs offer opportunities to understand the potential effects of future climate warming on arctic environments. A core from the Giraffe Pipe fossil locality located in the Northwest Territories of Canada offers a window into the life of a thriving Arctic freshwater ecosystem in the Eocene during greenhouse conditions. The remains of an extensive deposit of microfossils, including photosynthetic protists (chrysophytes, diatoms, and green algae), heterotrophic protists (euglyphids, heliozoans, paraphysomonads, and rotosphaerids), and sponges, were used to reconstruct the history of the ancient waterbody. Concentrations and diversity of chrysophyte taxa were extensive throughout the core, accounting for >70% of the microfossil remains. The ratio of chrysophyte cysts to diatom valves, with a mean value near 14 throughout the core, further emphasized the dominance of the chrysophytes, and given the high diversity of taxa, the locality represents a “paleo-hotspot” for this eukaryote lineage. Based on the totality of fossil evidence, the waterbody within the Giraffe Pipe crater represented a series of relatively shallow aquatic habitats, with changing physical and chemical conditions, and varying water depths. Five major zones were identified, each found to be stable for an extended period of time, but with distinct transitions between successive zones signaling significant shifts in environmental conditions. The study provides valuable insight on how Arctic freshwater ecosystems responded to past warm climates, and to the organisms that could potentially thrive in these environments under future warming scenarios.