Collaborative Research: Interactions Among Deposit-Feeding, Organic Matter Diagenesis andAnimal Nutrition

沉积物补给对碳埋藏的全球影响是深远的。尽管它们只消耗一小部分沉积有机质(OM)，但沉积物供给者通过增加沉积物中的氧气渗透率、重新分配颗粒并刺激整个混合层的成岩活动来影响OM成岩的速度和程度。沉积有机资源同时决定了底栖动物的活动，并由其决定。了解沉积物补给和有机质成岩作用是如何相互作用的，对于开发海洋沉积物中碳循环的实际耦合生物/化学模型至关重要。在这项研究中，斯基德韦海洋研究所和德克萨斯大学奥斯汀分校的研究人员将通过检测传送带在实验微宇宙中摄食奥尔贝类多毛类动物(Haplosstroplos Robust Us)的觅食行为，来研究OM成岩作用和沉积物-喂食者生态之间的联系和反馈。沉积有机质浓度对个体摄食率、斑块密度和速率x密度交互作用的影响将从最佳觅食角度进行研究。记录个体功能反应、沉积物混合、微生物介导的有机转化和养分同化之间的动态平衡是拟议研究的主要重点。为了研究生物-微生物-沉积物耦合系统，提出了一种新的基于同位素异构体的13C示踪实验。沉积碳和标记的OM加成的细菌共代谢将导致细菌合成的OM具有不同于(12C)沉积碳和添加的(13C)OM的分子13C同位素特征。测量添加的标签并入细菌氨基酸和脂肪酸池以及随后沉积的饲养器生物量将被用来追踪碳的命运作为粗壮梭子虫摄食率和种群密度的函数。有机质成岩作用、微生物生产、蠕虫觅食行为和生长之间的反馈将通过独立操纵有机供应、种群密度和沉积物混合速率来量化。就更广泛的影响而言，这项研究项目将以几个机构间的合作为特色，并将涉及培训一名研究生(在德克萨斯大学)和两名本科生从SKIO/Savannah State Cre实习计划。

The global effects of deposit feeding on carbon burial are profound. Even though they consume only a small fraction of sedimentary organic matter (OM), deposit feeders influence the rate and extent of OM diagenesis by increasing oxygen penetration into sediments, redistributing particles, and stimulating diagenetic activity throughout the mixed layer. Sedimentary organic resources simultaneously determine, and are determined by, the activities of the benthic infauna. Understanding how deposit feeding and OM diagenesis interact is critical to developing realistically coupled biological/chemical models of carbon cycling in marine sediments. In this study, investigators at the Skidaway Institute of Oceanography and the University of Texas at Austin will study linkages and feedbacks between OM diagenesis and deposit-feeder ecology by examining the foraging behavior of a conveyor-belt feeding orbiniid polychaetes (Haploscoloplos robustus) in experimental microcosms. Effects of sedimentary OM concentrations on individual feeding rates, patch density, and rate x density interactions will be examined from an optimal foraging perspective. Documenting the dynamic balance among individual functional responses, sediment mixing, microbially-mediated organic transformations, and nutrient assimilation is a major focus of the proposed study. To study the coupled organism-microbe-sediment system, a novel isotopomer-based 13C tracer experiment is proposed. Bacterial co-metabolism of sedimentary carbon and labeled OM additions will lead to the formation of bacterially-synthesized OM having molecular 13C isotopic signatures that are distinct from both the (12C) sedimentary carbon and the added (13C) OM. Measurement of the incorporation of added label into a bacterial amino acid and fatty acid pools and subsequently deposit feeder biomass will be used to trace the fate of carbon as a function of H. robustus feeding rate and population density. Feedbacks among OM diagenesis, microbial production, and worm foraging behavior and growth will be quantified by independently manipulating organic supply, population density, and sediment mixing rate.In terms of broader impacts, this research project will feature several inter-institutional collaborations and will involve the training one graduate student (at UT) and two undergraduate students from the SkIO/Savannah State CIRE internship program.