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

点击翻译按钮获取中文摘要

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.