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

在早期由国家科学基金会资助的海绵氮循环研究中，位于查佩尔山的北卡罗来纳州大学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。他们在现场测量整个海绵呼吸，抽水速率和化学通量表明，以前的研究的基础上外壳或实验室实验严重低估了净通量，不能提供所需的数据，以建立实际的净通量溶解无机氮（DIN）和其他N物种。海洋海绵强烈影响氮循环在沿海环境中，通过泵送和过滤大量的水，而其宿主微生物影响范围广泛的氮转化，包括硝化和溶解和颗粒有机氮的吸收和降解，并可能N2固定和反硝化，从而增加或减少沿海系统的生物可利用氮。海绵DIN通量覆盖沃茨在海螺礁，佛罗里达键，是大于任何其他底栖N源，应该是海绵丰富的所有沿海系统的情况。在该奖项下的额外资金，该团队将加入由地球化学同事在夏威夷大学的努力，他量化海绵对沿海氮循环的影响（i）使用原位方法来构建准确的N预算海绵，将确定他们作为营养源或汇，（ii）调查环境控制海绵介导的N转换。海绵对海洋地球化学氮循环的净影响在很大程度上是未知的。这项新的工作将是第一个使用原位方法来量化海绵中的氮循环和由此产生的海绵DIN和DON通量。该项目将产生一些更广泛的影响。在这项研究中获得的信息，虽然直接适用于海绵物种的一个子集，将有广泛的影响，在沿海生态系统丰富的海绵氮地球化学。一个研究生和几个本科生将在实验室和现场环境中学习一系列最先进的技术和仪器，当结果最终合成出版时，将受益于与来自不同领域的研究人员交流思想。夏威夷大学是指定的EPSCoR机构，也是联邦政府承认的少数民族服务机构，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，利用北卡罗来纳州大学与地球生态国际（Phillipe Cousteau，校长）和海底科学组织建立的联系，教育项目，重要的公共宣传工作将产生，包括来自AQUARIUS的与全国高中和中学生的实时网络视频会议。

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.