Functional Diversity of Subsurface Deposit Feeders

地下矿床馈送器的功能多样性

• 批准号: 0851172
• 负责人: Peter Jumars
• 金额: $ 49.92万
• 依托单位: University of Maine
• 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: 2009-06-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0851172&HistoricalAwards=false
• 关键词: Functional; Diversity; Subsurface; Deposit; Feeders

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."Benthic community composition is changing at an alarming rate in many coastal regions. At the extreme of macrofaunal change, "dead zones" are growing in number, frequency and extent. Ecological extinction is occurring in many localities before the functional roles of the lost species are understood even crudely. Subsurface deposit feeders dominate particulate bioturbation and control the burial of organic matter, the primary process by which carbon is removed globally from contact with the biosphere and locked away for geological time. Very little is known, however, regarding the mechanics, spatial geometry and selectivity of their food acquisition and their mechanisms of particle translation. The absence of that information effectively blocks the use of sophisticated, agent-based or automaton models that project deposit-feeder effects on substrata from ecological to geological time. Two principal obstacles have blocked understanding. One is the difficulty of making direct observations through mud. The second is a lack of understanding of the mechanics of the medium on the space and time scales of animal burrowing and feeding. Both problems have been greatly alleviated simultaneously, making this work possible now.Physics of the medium constrain what is possible. They also determine in concert with other features (e.g., food quality of the medium) what behaviors and processing rates are optimal. The investigators have two simultaneous goals. One is to test hypotheses about how subsurface deposit feeders free particles from the medium that they crack, and the other is to measure the per-event and per-individual sedimentary consequences in the context of particulate bioturbation. They will systematically do so in the major polychaete groups of subsurface deposit feeders and opportunistically do so in other subsurface deposit feeders. Explicit hypotheses to be tested (phrased as the more interesting alternative hypothesis rather than the null) include: that crack propagation produces elastic-plastic deformation, mixing sediment at the crack tip; that crack propagation displaces particles gravitationally, that friction of animal surfaces with crack boundaries displaces particles; and, that unsteady flows in the burrow created by pressure pulses associated with crack propagation free particles from the matrix and displace them.The broader impacts include a better understanding and development of updated diagrams for textbooks showing what seabed invertebrates do and how they do it. In addition, the investigators will work with COSEE-OS to produce compelling and accurate graphics about the role of bioturbation in complicating interpretation of the geological record and in gating the step in the carbon cycle that removes carbon from contact with the current biosphere. This outreach is designed to cover the spectrum of specialists and interested students of all ages who want to be informed about the ecology of the seabed and its role in global carbon cycling.

“这项奖励是根据2009年美国复苏和再投资法案（公法111-5）资助的。”在许多沿海地区，底栖生物群落的组成正在以惊人的速度变化。在大型动物变化的极端情况下，“死亡区”的数量、频率和范围都在增加。在许多地方，生态灭绝正在发生，甚至在失去的物种的功能作用被粗略地理解之前。地下沉积物喂养者控制着颗粒生物扰动，并控制着有机质的埋藏，有机质是碳从与生物圈接触中被全球移除并锁定地质时间的主要过程。然而，关于它们获取食物的力学、空间几何和选择性以及它们的粒子平移机制，我们知之甚少。这些信息的缺失有效地阻碍了复杂的、基于主体的或自动机模型的使用，这些模型可以预测从生态到地质时间对基底的沉积物馈送效应。有两个主要障碍阻碍了理解。其一是在泥泞中进行直接观察的困难。第二是缺乏对动物挖洞和进食的空间和时间尺度上的介质机制的理解。这两个问题同时得到了极大的缓解，使这项工作现在成为可能。介质物理学限制了一切可能。它们还与其他特征（例如，媒介的食品质量）一起决定什么行为和加工速度是最佳的。调查人员同时有两个目标。一个是测试关于地下沉积物如何从它们破裂的介质中释放颗粒的假设，另一个是在颗粒生物扰动的背景下测量每个事件和每个个体的沉积后果。它们会系统地在地下沉积物捕食者的主要多毛类群体中这样做，并偶然地在其他地下沉积物捕食者中这样做。需要测试的明确假设（措辞为更有趣的替代假设而不是零假设）包括：裂纹扩展产生弹塑性变形，在裂纹尖端混合沉积物；裂纹扩展使颗粒发生重力位移，动物表面与裂纹边界的摩擦使颗粒发生位移；并且，由与裂纹扩展相关的压力脉冲产生的不稳定流将颗粒从基体中解放出来并取代它们。更广泛的影响包括更好地理解和发展更新的教科书图表，显示海底无脊椎动物做什么以及它们是如何做的。此外，研究人员将与COSEE-OS合作，制作令人信服的精确图形，说明生物扰动在复杂的地质记录解释中所起的作用，以及控制碳循环中与当前生物圈接触的碳的步骤。这一外联活动的目的是为希望了解海底生态及其在全球碳循环中的作用的各年龄段的专家和感兴趣的学生提供服务。