Georgieva Magdalena N, Taboada Sergi, Riesgo Ana, Díez-Vives Cristina, De Leo Fabio C, Jeffreys Rachel M, Copley Jonathan T, Little Crispin T S, Ríos Pilar, Cristobo Javier, Hestetun Jon T, Glover Adrian G
Life Sciences Department, Natural History Museum, London, United Kingdom.
Departamento de Biología (Zoología), Universidad Autónoma de Madrid, Madrid, Spain.
Front Microbiol. 2020 Jul 24;11:1636. doi: 10.3389/fmicb.2020.01636. eCollection 2020.
The peripheral areas of deep-sea hydrothermal vents are often inhabited by an assemblage of animals distinct to those living close to vent chimneys. For many such taxa, it is considered that peak abundances in the vent periphery relate to the availability of hard substrate as well as the increased concentrations of organic matter generated at vents, compared to background areas. However, the peripheries of vents are less well-studied than the assemblages of vent-endemic taxa, and the mechanisms through which peripheral fauna may benefit from vent environments are generally unknown. Understanding this is crucial for evaluating the sphere of influence of hydrothermal vents and managing the impacts of future human activity within these environments, as well as offering insights into the processes of metazoan adaptation to vents. In this study, we explored the evolutionary histories, microbiomes and nutritional sources of two distantly-related sponge types living at the periphery of active hydrothermal vents in two different geological settings ( from the E2 vent site on the East Scotia Ridge, Southern Ocean, and from the Endeavour vent site on the Juan de Fuca Ridge, North-East Pacific) to examine their relationship to nearby venting. Our results uncovered a close sister relationship between the majority of our E2 specimens and the species , known to harbor and obtain nutrition from methanotrophic symbionts at cold seeps. Our microbiome analyses demonstrated that both E2 and Endeavour sp. are associated with putative chemosynthetic Gammaproteobacteria, including Thioglobaceae (present in both sponge types) and Methylomonaceae (present in sp.). These bacteria are closely related to chemoautotrophic symbionts of bathymodiolin mussels. Both vent-peripheral sponges demonstrate carbon and nitrogen isotopic signatures consistent with contributions to nutrition from chemosynthesis. This study expands the number of known associations between metazoans and potentially chemosynthetic Gammaproteobacteria, indicating that they can be incredibly widespread and also occur away from the immediate vicinity of chemosynthetic environments in the vent-periphery, where these sponges may be adapted to benefit from dispersed vent fluids.
深海热液喷口的周边区域常常栖息着一群与生活在喷口烟囱附近的动物不同的生物。对于许多此类分类群而言，人们认为与背景区域相比，喷口周边的种群丰度峰值与坚硬基质的可利用性以及喷口处产生的有机物质浓度增加有关。然而，与喷口特有分类群的组合相比，喷口周边区域的研究较少，周边动物群从喷口环境中获益的机制通常也不为人所知。了解这一点对于评估热液喷口的影响范围、管理未来人类活动在这些环境中的影响，以及深入了解后生动物对喷口的适应过程至关重要。在本研究中，我们探究了生活在两种不同地质环境（南大洋东斯科舍海岭的E2喷口站点和东北太平洋胡安德富卡海岭的奋进号喷口站点）中活跃热液喷口周边的两种远缘海绵类型的进化历史、微生物群落和营养来源，以研究它们与附近热液排放的关系。我们的研究结果揭示，我们的大多数E2样本与已知在冷泉中从甲烷营养共生体中获取营养的物种之间存在紧密的姐妹关系。我们的微生物群落分析表明，E2海绵和奋进号海绵均与假定的化学合成γ-变形菌有关，包括硫球杆菌科（两种海绵类型中均存在）和甲基单胞菌科（存在于奋进号海绵中）。这些细菌与深海贻贝的化学自养共生体密切相关。两种喷口周边海绵均显示出与化学合成对营养的贡献一致的碳和氮同位素特征。这项研究扩展了后生动物与潜在化学合成γ-变形菌之间已知关联的数量，表明它们可能极为广泛，并且也出现在喷口周边远离化学合成环境直接区域的地方，这些海绵可能已适应从分散的喷口流体中获益。
