Bathyal Microaerophiles: Life Positions and Adaptations of the Santa Barbara Basin Benthos

尽管丝状硫化物氧化细菌Beggiatoa的垫子在浅海地带下分布得相当广泛，但人们对栖息在这些垫子上的真核生物知之甚少。标本丢失和空间信息的破坏是过去用于研究这些脆弱沉积群落的方法的重大障碍。为了克服这些限制，开发了一种新的采样技术，即沉积物岩心与荧光探针孵育以标记所包含的生物群，然后进行化学固定、脱水并与低粘度的环氧树脂包埋。结合新的厚切片方法、共聚焦显微镜和最先进的数字图像处理技术，这种荧光标记嵌入岩芯(FLEC)技术提供了圣巴巴拉盆地(SBB)Beggiatoa垫子群落(SBB)无与伦比的精细结构视图。根据使用FLEC方法的初步研究，假设Beggiatoa构建了化学微环境，使微需氧菌能够生活在厌氧菌和需氧菌附近(即，在这方面，这些垫子可以被认为类似于细菌生物膜)。为了推进这一假设，本研究的主要目的是将小型底栖动物的生活位置及其生理适应与FineScale化学和空间信息相关联。此外，对SBB Beggiatoa垫子的初步FLEC研究产生了两个未描述的物种或更高的类群，以及三个新的和意想不到的细菌真核生物共生，这表明圣巴巴拉盆地为更多未描述的物种或共生提供了栖息地。据推测，具有化学自养的小型动物栖息在Beggiatoa垫层以下的区域，具有代谢适应能力的小型动物或异养共生体与Beggiatoa共存，而没有特殊适应的小型动物栖息在Beggiatoa垫层上方的空间。

Despite the fact that mats of the filamentous sulfide oxidizing bacteria Beggiatoa are quite extensive below the neritic zone, very little is known about the eukaryotic organisms inhabiting these mats. Specimen loss and destruction of spatial information are significant obstacles to past approaches used to study these fragile sedimentary communities. To overcome these limitations, a new sampling technique was developed in which sediment cores are incubated with a fluorogenic probe to label the contained biota, and then chemically fixed, dehydrated, and embedded with low viscosity epoxy resin. Combined with novel thick sectioning methods, confocal microscopy, and state of the art digital image processing, this fluorescently labeled embedded core (FLEC) technique has provided unparalleled views of the fine scale structure of the Beggiatoa mat community in the Santa Barbara Basin (SBB). Based on initial studies using the FLEC method, it is hypothesized that Beggiatoa structures the chemical microenvironment to allow microaerophiles to live in close proximity to anaerobes and aerobes (i.e., these mats might be considered analogous to bacterial biofilms in this respect). To advance this hypothesis, the major objective of this study is to correlate meiofaunal life positions and their physiological adaptations with finescale chemical and spatial information. Furthermore, the initial FLEC studies of SBB Beggiatoa mats yielded two undescribed species or higher taxa, as well as three new and unexpected bacterial eukaryote symbioses, suggesting that the Santa Barbara Basin provides habitat for yet more undescribed species or symbioses. It is hypothesized that meiofauna possessing chemoautotrophs inhabit zones below the Beggiatoa mat, meiofauna possessing metabolic adaptations or heterotrophic symbionts co exist with the Beggiatoa, and meiofauna without special adaptations inhabit space available above the Beggiatoa mat.