Metazoans of redoxcline sediments in Mediterranean deep-sea hypersaline anoxic basins.
Metazoans of redoxcline sediments in Mediterranean deep-sea hypersaline anoxic basins.
复制标题
DOI：
10.1186/s12915-015-0213-6
复制
发表时间：
2015-12-10
期刊：
影响因子：
5.4
通讯作者：
Edgcomb VP
中科院分区：
文献类型：
--
作者：
Bernhard JM;Morrison CR;Pape E;Beaudoin DJ;Todaro MA;Pachiadaki MG;Kormas KA;Edgcomb VP
地中海的深海高盐缺氧盆地（水深约3500米）是已知的最极端的海洋栖息地之一。dhab的盐水几乎饱和了盐，导致许多人怀疑它们不适合真核生物居住。虽然在一些DHAB盐层和盐水中发现了多种细菌和原生生物群落，但据报道，在缺氧的DHAB盐水中生活的后生动物只有loriciferans。我们的目标是进一步调查DHAB盐碱和盐水中的后生动物群落。我们报告了三个DHAB （Urania, Discovery, L 'Atalante）盐斜沉积物的观测结果，并将这些观测结果与典型地中海盐度的常压水域沉积物的观测结果进行了比较。由于技术上的困难，无法对盐水取样。形态型分析表明线虫是最丰富的分类单元；甲壳类、蛭形虫类和苔藓虫类也被发现。线虫属中数量最多的属为Daptonema；三种形态有一定程度的地方性。大多数rRNA序列来自浮游生物分类群，这表明至少有一些个体的后生动物被保存下来并且不活跃。线虫丰度数据，在某些情况下，通过直接计数在原位孵育的CellTrackerTM Green沉积物中确定，是不完整的，但通常表明在常温对照样品或上盐跃层样品中丰度最高；线虫在低盐层样品中不存在或非常罕见。超微结构分析表明，L 'Atalante常压对照沉积物中的线虫是健康的，而L 'Atalante上盐层的标本是健康的或刚刚死亡的，而来自下盐层的标本没有可识别的细胞器。在常温对照样品以及Discovery和L 'Atalante盐井中都发现了很少遇到的Loriciferans。目前尚不清楚一个后生动物分类群是如何在如此广泛的条件下保持存活的。我们记录了一个生活在常氧，正常盐水地中海深海沉积物和dhab上部盐斜部分的线虫群落。在中盐跃层和下盐跃层样品中出现的线虫并没有提供令人信服的证据表明这些地区有生物群落。目前我们的数据不支持在dhab盐水中存在可行的后生动物群落的可能性。本文的在线版本（doi:10.1186/s12915-015-0213-6）包含补充材料，可供授权用户使用。
The deep-sea hypersaline anoxic basins (DHABs) of the Mediterranean (water depth ~3500 m) are some of the most extreme oceanic habitats known. Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB haloclines and brines, loriciferans are the only metazoan reported to inhabit the anoxic DHAB brines. Our goal was to further investigate metazoan communities in DHAB haloclines and brines. We report observations from sediments of three DHAB (Urania, Discovery, L’Atalante) haloclines, comparing these to observations from sediments underlying normoxic waters of typical Mediterranean salinity. Due to technical difficulties, sampling of the brines was not possible. Morphotype analysis indicates nematodes are the most abundant taxon; crustaceans, loriciferans and bryozoans were also noted. Among nematodes, Daptonema was the most abundant genus; three morphotypes were noted with a degree of endemicity. The majority of rRNA sequences were from planktonic taxa, suggesting that at least some individual metazoans were preserved and inactive. Nematode abundance data, in some cases determined from direct counts of sediments incubated in situ with CellTrackerTM Green, was patchy but generally indicates the highest abundances in either normoxic control samples or in upper halocline samples; nematodes were absent or very rare in lower halocline samples. Ultrastructural analysis indicates the nematodes in L’Atalante normoxic control sediments were fit, while specimens from L’Atalante upper halocline were healthy or had only recently died and those from the lower halocline had no identifiable organelles. Loriciferans, which were only rarely encountered, were found in both normoxic control samples as well as in Discovery and L’Atalante haloclines. It is not clear how a metazoan taxon could remain viable under this wide range of conditions. We document a community of living nematodes in normoxic, normal saline deep-sea Mediterranean sediments and in the upper halocline portions of the DHABs. Occurrences of nematodes in mid-halocline and lower halocline samples did not provide compelling evidence of a living community in those zones. The possibility of a viable metazoan community in brines of DHABs is not supported by our data at this time. The online version of this article (doi:10.1186/s12915-015-0213-6) contains supplementary material, which is available to authorized users.