Collaborative Research: The Influence of Sponge Holobiont Metabolism on Coral Reef Dissolved Organic Matter and Reef Microorganisms

合作研究：海绵全生物代谢对珊瑚礁溶解有机物和珊瑚微生物的影响

• 批准号: 1923962
• 负责人: Amy Apprill
• 金额: $ 24.33万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1923962&HistoricalAwards=false
• 关键词: Collaborative; Research; Influence; Sponge; Holobiont

The seawater around coral reefs is typically low in nutrients, yet coral reefs are teeming with life and are often compared to oases in a desert. Life exists in these 'marine deserts' in large part, due to symbiotic associations between single-celled microbes and invertebrates such as corals and sponges. The concentration and type of dissolved organic matter (DOM), a complex pool of organic nutrients such as amino acids, vitamins, and other diverse compounds, also affects the health of coral reefs. The composition of DOM on coral reefs is linked to both the composition of free-living microbes in the seawater and to the nutrition of filter-feeding organisms, such as corals and sponges. However, the factors that influence the composition of DOM on coral reefs and the consequences of how it changes are not well understood. Recent work suggests that sponges could have a significant impact on the composition of reef dissolved organic nutrients, depending on sponge species due to differences in filtration capacity and in their symbiotic microbial communities. This project characterizes how diverse sponge species process DOM on coral reefs and determines the impacts of this processing on the free-living microbial community. Seawater is collected from sponges (pre- and post- sponge filtration) on coral reefs in the relatively pristine region of Curacao, and incubation experiments measure the impact of sponge filtration on the growth of the free-living microbial community. The organic nutrients of seawater samples are analyzed using cutting-edge techniques to distinguish the types of nutrients that are processed by sponges. The incubation experiments, using free-living microbes collected from the coral reef, quantify the impact of sponge filtration on the growth and composition of this community. This project provides fundamental understanding of how sponges contribute to the base of the coral reef food web. As the human-driven impacts continue to alter the composition of organisms on reefs, this understanding is necessary to predict changes to reef microbial food webs and is thus essential for scientists, reef managers, and policy decision makers. This project trains undergraduate students and a postdoctoral scholar and contributes to undergraduate and K-12 education through development of sponge-centric lessons that focus on local U.S. east coast aquatic environments as well as coral reef ecosystems. Sponges vary in their capacity to filter seawater and in their associated microbial communities, leading to diverse metabolic strategies that often coexist in one habitat. While it is well-established that sponges are important in processing dissolved organic matter (DOM), an important reservoir of reduced carbon compounds, and transferring this energy to benthic food webs, there has been limited work to understand the consequences of sponge processing on the composition of coral reef DOM and on pelagic food webs. Specifically, while studies have shown that exudates of corals and algae select for specific groups of picoplankton (autotrophic and heterotrophic, respectively), similar data for sponges are required to understand the multiple factors that shape the composition of DOM and of the picoplankton community on coral reefs. Thus, this project is aimed at addressing a major knowledge gap of the role of sponge-derived DOM (sponge exometabolome) in coral reef biogeochemistry. An in situ sampling design targeting prominent Caribbean sponges and picoplankton incubation experiments is coupled to address both the composition of sponge exometabolomes and delineate shifts in the picoplankton community derived from sponge exometabolomes. Molecular-level changes to seawater DOM by sponge processing and the impact of these changes on the overall coral reef DOM profile is assessed with two DOM analysis techniques: a commonly used fluorometry technique (fDOM analysis) and with high-resolution mass spectrometry (LC-MS/MS). Additionally, microbiome and functional gene profiling, growth metrics, and nutrient analyses are employed to assess changes in the picoplankton community in response to sponge exometabolomes. Advanced data analysis techniques then synthesize data generated by each approach to provide novel insight on a poorly uncharacterized biogeochemical pathway on coral reefs. The work outlined here represents entirely novel information on the impact of sponge metabolism on the composition of DOM, sheds light on biologically important molecules involved in benthic-pelagic coupling, and importantly, generates data using standardized methods, thus facilitating comparison to previous and future DOM datasets.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

珊瑚礁周围的海水营养通常很低，但珊瑚礁充满了生命，经常被比作沙漠中的绿洲。生命存在于这些“海洋沙漠”中，很大程度上是由于单细胞微生物与珊瑚和海绵等无脊椎动物之间的共生关系。溶解有机物(DOM)的浓度和类型也影响珊瑚礁的健康。DOM是氨基酸、维生素和其他各种化合物等有机营养素的复合池。珊瑚礁上DOM的组成既与海水中自由生活的微生物的组成有关，也与珊瑚和海绵等滤食性生物的营养有关。然而，影响珊瑚礁上DOM组成的因素以及它如何变化的后果还没有被很好地了解。最近的工作表明，海绵可能对珊瑚礁溶解的有机营养物质的组成产生重大影响，这取决于海绵种类，因为过滤能力和共生微生物群落的差异。该项目描述了不同的海绵物种如何处理珊瑚礁上的DOM，并确定了这种处理对自由生活的微生物群落的影响。海水是从库拉索岛相对原始地区珊瑚礁上的海绵(海绵过滤前和海绵过滤后)收集的，培养实验测量了海绵过滤对自由生活微生物群落生长的影响。使用尖端技术分析海水样本的有机营养物质，以区分海绵加工的营养物质类型。孵化实验使用从珊瑚礁收集的自由生活的微生物，量化了海绵过滤对这个群落的生长和组成的影响。这个项目提供了对海绵如何为珊瑚礁食物网的基础做出贡献的基本理解。由于人类驱动的影响继续改变着珊瑚礁上生物的组成，这种了解对于预测珊瑚礁微生物食物网的变化是必要的，因此对于科学家、珊瑚礁管理者和政策制定者来说也是至关重要的。该项目培养本科生和博士后学者，并通过开发以海绵为中心的课程，重点关注美国东海岸当地的水环境和珊瑚礁生态系统，为本科生和K-12教育做出贡献。海绵过滤海水的能力和相关微生物群落的能力不同，导致不同的新陈代谢策略往往共存于一个栖息地。虽然众所周知，海绵在处理溶解有机物(DOM)和将这种能量转移到海底食物网方面很重要，DOM是还原碳化合物的重要储存库，但了解海绵加工对珊瑚礁DOM组成和中上层食物网的影响的工作有限。具体地说，虽然研究表明，珊瑚和藻类的渗出物选择特定的微浮游生物群(分别为自养和异养)，但需要海绵的类似数据才能理解影响珊瑚礁上DOM和微浮游生物群落组成的多种因素。因此，该项目旨在解决关于海绵来源的DOM(海绵外代谢组)在珊瑚礁生物地球化学中的作用的重大知识空白。针对突出的加勒比海绵的现场抽样设计和微浮游植物孵化实验相结合，既研究了海绵外代谢体的组成，又描绘了海绵外代谢体衍生的微浮游生物群落的变化。利用两种DOM分析技术：常用的荧光分析技术(fDOM分析)和高分辨率质谱仪(LC-MS/MS)，评估了海绵加工对海水DOM分子水平的变化以及这些变化对整个珊瑚礁DOM剖面的影响。此外，微生物组和功能基因图谱、生长指标和营养分析被用来评估微微浮游生物群落对海绵外代谢体的响应变化。然后，先进的数据分析技术综合每种方法产生的数据，以提供对珊瑚礁上不太典型的生物地球化学途径的新见解。这里概述的工作代表了关于海绵新陈代谢对DOM组成的影响的全新信息，揭示了参与海底-水上耦合的生物重要分子，重要的是，使用标准化方法生成数据，从而便于与以前和未来的DOM数据集进行比较。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。