Collaborative Proposal: In Situ Quantification of Sponge N Cycling in Coastal Ecosystems

在早先由美国国家科学基金会资助的海绵氮循环研究中，北卡罗来纳大学教堂山分校的一个研究小组证明，海绵在珊瑚礁和其他浅水热带生态系统的氮收支中起着重要作用。他们对整个海绵呼吸、抽水速率和化学通量的现场测量表明，以前基于围栏或实验室实验的研究严重低估了净通量，并且不能提供确定溶解无机氮(DIN)和其他N物种的实际净通量所需的数据。海绵通过泵送和过滤大量的水来强烈影响沿海环境中的氮循环，而它们的宿主微生物影响广泛的氮转化，包括硝化作用和溶解和颗粒有机氮的吸收和降解，以及潜在的氮固定和反硝化作用，从而增加或减少沿海系统中的生物有效氮。海绵进入佛罗里达群岛海螺礁上覆水域的海绵DIN通量比任何其他底栖N源都要大，这应该是所有海绵丰富的海岸系统的情况。有了这项奖励下的额外资金，北卡罗来纳大学的团队将与夏威夷大学的生物地球化学同事一起努力量化海绵对沿海N循环的影响，方法是：(I)使用原位方法来构建准确的海绵N预算，以确定它们是营养源或汇，以及(Ii)调查海绵介导的N转化的环境控制。海绵对沿海环境中生物地球化学氮循环的净影响在很大程度上是未知的。这项新工作将首次使用原位方法来量化海绵中的氮循环以及由此产生的海绵中DIN和DON的通量。该项目将产生一些更广泛的影响。这项研究获得的信息虽然直接适用于海绵物种的子集，但将对海绵丰富的沿海生态系统中的氮生物地球化学具有广泛的影响。一名毕业生和几名本科生将在实验室和现场环境中第一手学习一系列最先进的技术和仪器，当结果最终综合发表时，将受益于与来自不同领域的知名研究人员进行思想交流。夏威夷大学是指定的EPSCoR机构和联邦承认的少数群体服务机构，因此来自代表性不足群体的学生很可能被纳入拟议研究的参与者，并将从这项研究结果产生的教育活动中受益。最后，利用北卡罗来纳大学与地球生态国际(总裁菲利普·库斯托)和海底科学组织建立的联系，教育项目将产生重大的公共宣传努力，包括来自宝瓶座的现场网络视频会议，全国各地的高中生和中学生。

ABSTRACTOCE-0624406 / OCE-0624703In earlier NSF-funded investigations of nitrogen cycling in sponges, a research team at the University of North Carolina at Chapel Hill demonstrated that sponges play a major role in the N budget of coral reef and other shallow water tropical ecosystems. Their in situ measurements of whole sponge respiration, water pumping rates and chemical fluxes indicate that previous studies based upon enclosure or laboratory experiments seriously underestimate net fluxes and cannot provide data needed to establish actual net fluxes of dissolved inorganic nitrogen (DIN) and other N species. Marine sponges strongly affect N cycling in coastal environments through pumping and filtering tremendous volumes of water while their hosted microorganisms affect a wide range of N transformations, including nitrification and dissolved and particulate organic nitrogen uptake and degradation, and potentially N2 fixation and denitrification, thereby adding or subtracting bioavailable N from coastal systems. Sponge DIN flux to overlying waters at Conch Reef, Florida Keys, is larger than any other benthic N source as should be the case for all coastal systems where sponges are abundant. With additional funding under this award, the UNC team will be joined by biogeochemical colleagues at the University of Hawaii in an effort he to quantify sponge impacts on coastal N cycles by (i) using in situ methodologies to construct accurate N budgets for sponges that will identify them as nutrient sources or sinks, and (ii) investigating environmental controls over sponge mediated N transformations. The net impact of sponges on biogeochemical N cycling in coastal environments is largely unknown. This new work will be the first to use in situ methods to quantify the nitrogen cycling in sponges and the resultant fluxes of DIN and DON from sponges. The project will have a number of broader impacts. The information gained in this study, although directly applicable to a subset of sponge species, will have broad implications for nitrogen biogeochemistry in coastal ecosystems with abundant sponges. A graduate and several undergraduate students 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, will benefit from participation in the exchange of ideas with established researchers from diverse fields. The University of Hawaii is a designated EPSCoR institution and a federally recognized minority serving institution, thus students from underrepresented groups are likely to be included as participants in the proposed research and will benefit from education activities stemming from the results of this research. Finally, using the University of North Carolina's established connections with Earth Eco International (Phillipe Cousteau, President) and the Science Under the Sea, educational projects, significant public outreach efforts will result including live web-based videoconferences from AQUARIUS with high school and middle school students across the country.