Collaborative Research: Macrofaunal community effects on benthic exchange fluxes

合作研究：大型动物群落对底栖交换通量的影响

• 批准号: 1014226
• 负责人: George Waldbusser
• 金额: $ 18.24万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2012-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1014226&HistoricalAwards=false
• 关键词: Collaborative; Research; Macrofaunal; community; effects

The seafloor plays a critical role in the elemental cycling within shallow water ecosystems. Although the coastal benthos has been relatively well studied, the quantitative role of infauna in modifying critical ecosystem services such as nutrient cycling remains still poorly constrained. This stems largely from difficulties in scaling biogeochemical dynamics observed at the plot (mm - m) scale to the larger framework of coastal ecosystems. In this collaborative project, researchers at the University of Georgia and the University of Maryland?s Chesapeake Biological Laboratory will quantify small-scale dynamics of infaunal activities and their ecological interactions under controlled conditions and incorporate these data into a novel modeling approach of sediment biogeochemistry. Specifically, they will carry out a series of experimental studies to 1) determine to what extent spatial arrangement of burrows in a complex 3-dimensional domain alters sediment biogeochemistry, 2) measure species-interaction effects and feedbacks on sediment biogeochemistry, and 3) use these findings to provide guidance on sampling the intrinsically heterogeneous coastal seafloor. Laboratory experiments will be developed using sediment microcosms with artificial burrows and real organisms ? the ubiquitous Arenicola cristata and Nereis diversicolor - in separate experiments. Fluxes between the sediment and the overlying water of several diagenetically and ecologically important solutes will be measured. Burrow mimic experiments will provide detailed empirical information on burrow irrigation and spatial orientation effects on sediment-seawater exchange. This information will be used to parameterize a three-dimensional reactive transport model. Microcosms containing different combinations of the two macrofaunal species distributed in even and clustered spatial arrangements will be used to determine species interaction effects on burrow geometry and irrigation, and consequences for solute fluxes. The experimental data will elucidate the response of infauna to spatial proximity as well as the interaction across and within species. Comparison of observational data to model simulations will be used to assess the impact of macrofaunal interactions on sediment biogeochemistry. Finally, reactive transport model simulations will be performed for scenarios differing in densities and spatial arrangement of macrofauna, as well as their interactions. Aggregate fluxes across the sediment water interface will be estimated by dividing the seafloor up into tiles for which model flux estimates can be obtained. This approach will be used to evaluate various possible sampling strategies, and determine how well a limited number of flux measurements can approximate the contribution of benthic infauna to coastal biogeochemical cycles. In terms of broader impacts, this study is expected to provide a framework for scaling individual flux measurements taken in coastal sediments to larger scale mass fluxes. The findings will broaden our understanding of nutrient dynamics in the coastal ocean and benefit the general experimental community by providing context for the interpretation of flux data and design of measurement campaigns. One graduate student will be trained in experimental and numerical methodology. In addition, development of outreach materials and exhibits about sediment biogeochemistry and benthic infauna for the CBL visitor center will expose roughly 3500 visitors per year to lesser known aspects of the marine environment.

海底在浅水生态系统的元素循环中起着至关重要的作用。尽管沿海底栖动物已得到相对充分的研究，但水下动物在改变养分循环等关键生态系统服务方面的定量作用仍然缺乏限制。这主要是由于难以将在地块（mm - m）尺度上观察到的生物地球化学动力学扩展到更大的沿海生态系统框架。在这个合作项目中，乔治亚大学和马里兰大学切萨皮克生物实验室的研究人员将量化受控条件下动物活动的小规模动态及其生态相互作用，并将这些数据纳入沉积物生物地球化学的新型建模方法中。具体来说，他们将进行一系列实验研究，以1）确定复杂3维域中洞穴的空间排列在多大程度上改变沉积物生物地球化学，2）测量物种相互作用对沉积物生物地球化学的影响和反馈，3）利用这些发现为内在异质的沿海海底采样提供指导。 实验室实验将使用具有人工洞穴和真实生物的沉积物微观世界进行？无处不在的Arenicola cristata 和沙蚕——在单独的实验中。将测量沉积物和上覆水之间的几种对成岩和生态重要的溶质的通量。洞穴模拟实验将提供有关洞穴灌溉和沉积物-海水交换的空间方向影响的详细经验信息。该信息将用于参数化三维反应传输模型。包含以均匀和聚集空间排列分布的两种大型动物物种的不同组合的微观世界将用于确定物种相互作用对洞穴几何形状和灌溉的影响，以及对溶质通量的影响。实验数据将阐明动物群对空间邻近性的反应以及物种间和物种内的相互作用。观测数据与模型模拟的比较将用于评估大型动物相互作用对沉积物生物地球化学的影响。最后，将对大型动物密度和空间排列不同的场景以及它们之间的相互作用进行反应性运输模型模拟。通过将海底划分为小块，可以估计沉积物水界面的总通量，从而获得模型通量估计值。该方法将用于评估各种可能的采样策略，并确定有限数量的通量测量可以在多大程度上近似底栖动物群对沿海生物地球化学循环的贡献。就更广泛的影响而言，这项研究预计将提供一个框架，用于将沿海沉积物中的个体通量测量扩展到更大规模的质量通量。这些发现将拓宽我们对沿海海洋营养动态的理解，并为通量数据的解释和测量活动的设计提供背景，使整个实验界受益。一名研究生将接受实验和数值方法方面的培训。此外，为 CBL 游客中心开发有关沉积物生物地球化学和底栖动物的宣传材料和展览，每年将使大约 3500 名游客接触到海洋环境鲜为人知的方面。