RAPID: Tracing the origin and fate of particulate organic matter in nearshore marine sediments

生态系统之间的物质交换日益被认为是许多生态模式和过程的重要决定因素。这一点在生产力高的沿海地区最为明显，那里通过溪流和河流排放接收大量陆地颗粒有机物质(POM)。在半干旱地区，如加利福尼亚州南部，陆地POM向近岸的输送在很大程度上仅限于厄尔尼诺年降雨量高于平均水平期间加剧的风暴事件。人们对这种物质的加工和去向知之甚少，但越来越多的证据表明，它可以对近岸的生产力做出重大贡献。这一研究项目将有助于填补关于陆地POM的来源、分布、加工及其作为近岸初级生产氮库的潜力的关键知识空白，在一年中海洋溶解无机氮来源低的时期。该奖项的研究将与圣巴巴拉海岸长期生态研究计划(SBC LTER)密切合作。因此，它将加强SBC在本科生、研究生和博士后水平的跨学科研究方面对学生培训和指导的强大贡献。成果将被纳入SBC正在进行的校园LTER计划，该计划围绕海藻森林生态和陆地-海洋交流的主题组织，旨在与服务不足、成绩低下的学校建立长期联系，包括全年的校内外活动。LTER的调查人员已经与当地城市和圣巴巴拉县建立了正式的合作伙伴关系，以开发该地区沿海生态系统的脆弱性评估，LTER将把这项研究的结果纳入这些评估中。加利福尼亚州目前已进入第四个年头的前所未有的干旱，加上持续存在的异常低的海洋生产力状况，以及有可能出现有记录以来最强的厄尔尼诺现象，为圣巴巴拉海岸长期生态研究计划(SBC LTER)的研究人员提供了一个无与伦比的机会，以检验与厄尔尼诺现象的起源、分布、沿海海洋沉积物中陆地有机质的加工和生物有效性，以及在硝酸盐浓度低的时期作为氮储存库为近岸初级生产提供燃料的潜力。NSF快速反应奖励资金将用于：(1)测量溪水和沿海海洋沉积物中颗粒有机物(POM)的总体特性和生物标志物示踪剂，这些沉积物位于SBC地点，这些地点在大型风暴事件之前和之后暴露于陆地径流，以及(2)确定大型径流事件后海洋沉积物中POM释放的溶解有机物(DOM)的生物有效性。这项研究将补充SBC正在进行的努力，以调查在硝酸盐水平通常较低的非上升期支持近岸大型植物和浮游植物初级生产的循环形态氮的可用性和利用情况。

Material exchange between ecosystems is being increasingly recognized as an important determinant of many ecological patterns and processes. Nowhere is this more evident than in the highly productive coastal zone, which receives large amounts of terrestrial particulate organic (POM) matter through stream and river discharge. In semi-arid regions such as southern California, the delivery of terrestrial POM to the nearshore is largely restricted to storm events that are intensified during El Nino years of above average rainfall. The processing and fate of this material is poorly known, yet there is growing evidence that it could contribute significantly to nearshore productivity. This research project will help to fill a critical knowledge gap pertaining to the origin, distribution, processing of terrestrial POM and its potential to serve as a reservoir of nitrogen storage for nearshore primary production during periods of the year when marine sources of dissolved inorganic nitrogen are low. Research on this award will be done in close collaboration with the Santa Barbara Coastal Long Term Ecological Research program (SBC LTER). As such it will augment SBC's strong contribution to student training and mentoring in interdisciplinary research at the undergraduate, graduate, and post-doctoral levels. Outcomes will be incorporated into SBC's ongoing Schoolyard LTER program, which is organized around a theme of kelp forest ecology and land-ocean exchanges and aimed at long-term connections with underserved, low-achieving schools that include year-round on and off campus activities. The LTER Investigators have developed formal partnerships with local cities and Santa Barbara County to develop vulnerability assessments of the regions coastal ecosystems and the LTER will incorporate the findings from this study into those assessmentsThe unprecedented drought currently in its fourth year in California, coupled with the ongoing conditions of anomalously low ocean productivity and the prospect of one the strongest El Ninos on record provide an unparalleled opportunity for researchers at the Santa Barbara Coastal Long Term Ecological Research program (SBC LTER) to test specific hypotheses pertaining to the origin, distribution, processing and bioavailability of terrestrial organic matter in coastal marine sediments and their potential for serving as a reservoir of nitrogen storage to fuel nearshore primary production during periods when nitrate concentrations are low. NSF RAPID Response award funds will be used to: (1) measure bulk properties and biomarker tracers of particulate organic matter (POM) in stream water and in coastal marine sediments at SBC sites differing in exposure to terrestrial runoff prior to and following large storm events, and (2) determine the bioavailability of dissolved organic matter (DOM) released from POM in marine sediments following large runoff events. The research will complement and inform SBC's ongoing efforts to investigate the availability and utilization of recycled forms of nitrogen in supporting the primary production of nearshore macrophytes and phytoplankton during non-upwelling periods when nitrate levels ar typically low.