Collaborative Research: The Role of Sponges in the Coastal Nitrogen Cycle

海绵通过非凡的抽水速率和快速、动态的生物地球化学转化的结合，极大地改变了生态系统的水质。海绵群落在海洋环境中无处不在，可居住在热带生态系统中40%以上的底栖生物区域。在这个项目中，来自北卡罗来纳大学教堂山分校、夏威夷大学马诺阿分校和华盛顿大学的一个研究小组将继续他们正在进行的调查，通过量化海绵氮(N)在佛罗里达湾氮循环中的作用，来研究海绵氮(N)转化和通量在沿海环境中的重要性，特别是这些优势底栖生物在满足整个海湾初级生产生物对氮的需求方面的重要性。该团队之前的研究表明，海绵溶解的无机氮（DIN）通量到佛罗里达群岛海螺礁的上覆水域，比任何其他底栖生物的氮(N)来源都要大。在选择佛罗里达湾作为他们的研究区域时，研究小组将受益于有关N来源和循环的丰富可用数据，包括新N输入的估定值和定量海绵底栖生物生物量。通过进行原位海绵N通量测量，他们希望能够提供关于一个潜在的重要的再循环N源的信息，这在以前的N预算中没有被量化。本研究的总体目标是确定海绵介导的N循环过程在佛罗里达湾的重要性，那里海绵丰富，它们的生物量已经在数百个站点进行了量化，并且通过量化主要海绵物种将溶解有机氮和颗粒有机氮转化为DIN和N2（氮气）的速率和机制，已经确定了它们在水过滤中的关键作用。阐明海绵组织溶解氧浓度等自然因素对N2生成的控制。更广泛的影响：海绵在沿海环境的营养平衡中起着至关重要的作用，因为它们在热带、温带和极地栖息地都很丰富，它们处理大量的水，许多常见物种都拥有丰富而活跃的微生物种群。然而，在大多数环境中，它们对生物地球化学循环的影响在很大程度上仍然未知。在这项研究中，研究生和本科生以及一名博士后将在实验室和现场学习一系列最先进的技术和仪器，当结果最终合成发表时，他们将从与来自不同领域的知名研究人员的思想交流中受益。

Sponges dramatically alter ecosystem water quality through the combination of extraordinary pumping rates and rapid, dynamic biogeochemical transformations. Sponge communities are ubiquitous in marine environments and can inhabit over 40% of the benthic area in tropical ecosystems. In this project, a research team from the University of North Carolina at Chapel Hill, the University of Hawaii at Manoa, and the University of Washington will continue their ongoing investigations of the importance of sponge nitrogen (N) transformations and fluxes in coastal environments through quantifying their role in the N cycle of Florida Bay, specifically the importance of these dominant benthic organisms in meeting the N demands of primary producers throughout the Bay. The team's previous research demonstrated that sponge dissolved inorganic nitrogen (DIN) flux to overlying waters at Conch Reef, Florida Keys, was larger than any other benthic nitrogen (N) source. In choosing Florida Bay as their study area, the team will benefit from the wealth of available data concerning N sources and recycling, including estimated values for new N inputs, and quantitative sponge benthic biomass. By performing in situ sponge N flux measurements they expect be able to contribute information about a potentially important recycled N source that has not previously been quantified in N budgets. The overarching goal of this research is to establish the importance of sponge-mediated N cycling processes in Florida Bay where sponges are abundant, their biomass has been quantified at hundreds of stations and their key role in water filtration has been established, by quantifying rates and mechanisms of transformations of both dissolved and particulate organic nitrogen to DIN and N2 (nitrogen gas) by key sponge species, and elucidating controls on N2 production by natural factors such as sponge tissue dissolved oxygen concentrations. Broader Impacts: Sponges play a crucial role in the nutrient balance of coastal environments because they are abundant in tropical, temperate and polar habitats, they process tremendous volumes of water, and many common species host abundant and active microbial populations. Their impact on biogeochemical cycling in most environments, however, remains largely unknown. During this study, graduate and undergraduate students and a postdoctoral fellow will learn in both laboratory and field settings a spectrum of state-of-the-art techniques and instrumentation firsthand and, when the results are ultimately synthesized for publication, they will benefit from participation in the exchange of ideas with established researchers from diverse fields.