Benthic foraminifera of dysoxic sediments: chloroplast sequestration and functional morphology
Benthic foraminifera of dysoxic sediments: chloroplast sequestration and functional morphology
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DOI：
10.1016/s0012-8252(99)00017-3
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发表时间：
1999-05-01
影响因子：
12.1
通讯作者：
Bowser, SS
中科院分区：
文献类型：
--
作者：
Bernhard, JM;Bowser, SS
我们最近对缺氧点和缺氧点的调查显示，许多常见的有孔虫居民隔离叶绿体。这些物种包括：非离子杆菌，它主导着圣巴巴拉盆地的层理沉积物，在[O-2]低于2亩M(类似于0.04毫升/L)时，它占生物组合的82%；与它关系密切的物种拉布拉多利亚非离子杆菌，它生活在瑞典的缺氧、硅藻峡湾中；未来海藻，它主要分布在挪威峡湾的缺氧沉积物中；以及优雅布立米纳，它丰富地分布在浅水石油渗漏点，支持丝状、硫化物氧化细菌Beggiatoa。这些文献包含至少8个种的例子，以及已知隔离叶绿体的其他三个有孔虫属(即海鞘藻属、非有孔虫属、Reophax属)中每个属的一个种。这些有孔虫通常是非动物群和/或可能生活在缺氧性条件下。被隔离的叶绿体的光合作用活动可能为寄主有孔虫提供氧气，从而使它们能够栖息在缺氧的孔隙水中。然而，考虑到大多数调查地点都发生在光照水平太低而不能促进光合作用的无光区，寄主更有可能采用了一种与隔离的叶绿体相关的迄今尚未确定的生化途径。此外，这些有孔虫有外部的测试装饰物，可能有助于将叶绿体与它们的猎物藻类分离。我们讨论了这些形态特征在解释化石记录中的潜在用途。(C)1999 Elsevier Science B.V.保留所有权利。
Our recent surveys of dysoxic and anoxic sites reveal that many of the common foraminiferal inhabitants sequester chloroplasts. Such species include: Nonionella stella, which dominates the laminated sediments of the silled Santa Barbara Basin and comprises up to 82% of the living assemblage when [O-2] is below 2 mu M (similar to 0.04 ml/l); the closely related species Nonionellina labradorica, which occurs in oxygen-depleted, silled fjords of Sweden; Stainforthia fusiformis, which dominates dysoxic sediments of Norwegian fjords; and Bulimina elegantissima, which is abundant in a shallow-water oil seep site supporting the filamentous, sulfide-oxidizing bacteria Beggiatoa. The literature contains examples of at least eight Elphidium species and one species from each of three other foraminiferal genera (i.e., Haynesina, Nonion, Reophax) that are known to sequester chloroplasts. These foraminifera are typically infaunal and/or may live under dysoxic conditions. Photosynthetic activity of the sequestered chloroplasts might provide oxygen to the host foraminifera, thereby enabling them to inhabit anoxic pore waters. However, given that most of the surveyed sites occur in the aphotic zone where light levels are too low to fuel photosynthesis, it is more likely that the host employs an as yet unidentified biochemical pathway associated with the sequestered chloroplasts. Additionally, these foraminifera have external test ornamentations that may facilitate separation of the chloroplasts from their algal prey. We discuss potential uses for these morphological features in interpreting the fossil record. (C) 1999 Elsevier Science B.V. All rights reserved.