Long-term ecosystem stability in an Early Miocene estuary
Long-term ecosystem stability in an Early Miocene estuary
复制标题
早中新世河口的长期生态系统稳定性
DOI：
10.1130/g34761.1
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发表时间：
2014
期刊：
影响因子：
5.8
通讯作者：
Reinhard Roetzel
中科院分区：
文献类型：
--
作者：
M. Zuschin;M. Harzhauser;Babette Hengst;O. Mandic;Reinhard Roetzel
生态系统稳定性问题是生态学和古生态学的核心问题，对于河口尤其重要，因为河口环境变化很大，被认为是地质寿命很短，是地球上退化最严重的现代生态系统之一。了解他们的生态动态在地质时间尺度上需要古生物学数据的层序地层框架，这使得在环境背景下的古群落动态评价。维也纳盆地（奥地利）卫星盆地中445 m厚的河口序列显示连续沉积超过700 k.y。可划分为两个水进体系域和一个高位体系域。与预期相反，没有重大的物理干扰的生态系统，涉及突然变化的多样性和生物相组成发生在fl表面和层序边界。在盆地的沉积历史中，可容纳空间保持显著的恒定，因此沉积环境之间的所有变化或多或少都是渐变的。生物的变化沿着研究的继承可以被描述为一个逐步的动物区系的替代，在生境跟踪，一个过程也报告了一些正常的海洋陆架环境。河口演替中底栖生物组合主要由少数类群控制，并沿着水深和水动力能两个间接梯度发展。这些梯度表现出微妙的长期趋势，对应于层序地层结构。构造影响了这一特定边缘海相环境中的层序结构：它控制了可容纳空间和沉积物输入，并提供了数十万年的稳定边界条件。我们的研究第一次表明，今天处于巨大环境压力下的河口对自然环境扰动具有弹性，并且可以在地质时间尺度上持续存在。
The question of ecosystem stability is central to ecology and paleoecology and is of particular importance for estuaries, which are environmentally highly variable, considered as geologically short lived, and among the most degraded modern ecosystems of our planet. Understanding their ecological dynamics over geological time scales requires paleontological data in a sequence stratigraphic framework, which allows evaluation of paleocommunity dynamics in an environmental context. A 445-m-thick estuarine succession in a satellite basin of the Vienna Basin (Austria) shows continuous sedimentation over 700 k.y. and can be divided into two transgressive systems tracts and a highstand systems tract. In contrast to expectations, no major physical disturbances of the ecosystem involving abrupt changes in diversity and biofacies composition occurred at fl surfaces and at the sequence boundary. Accommodation space remained remarkably constant over the depositional history of the basin, and all changes between depositional environments were therefore more or less gradational. Biotic change along the studied succession can be described as a gradual faunal replacement in response to habitat tracking, a process also reported for some normal marine shelf environments. Benthic assemblages in the estuarine succession were strongly dominated by a few taxa and developed along two indirect gradients, water depth and hydrodynamic energy. These gradients show subtle long-term trends, corresponding to the sequence stratigraphic architecture. Tectonics affected the sequence architecture in this particular marginal marine setting: it controlled accommodation space and sedimentary input, and provided stable boundary conditions over hundreds of thousands of years. Our study demonstrates for the fi rst time that estuaries, which are under great environmental pressure today, are resilient to natural environmental perturbations and can persist over geological time scales.