Mechanical consequences of flexibility for benthic marine organisms

底栖海洋生物灵活性的机械后果

• 批准号: 0523870
• 负责人: Brian Gaylord
• 金额: $ 13.35万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-11-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0523870&HistoricalAwards=false
• 关键词: Mechanical; consequences; flexibility; benthic; marine

Scientific context and intellectual merit: Mechanically flexible, benthic plants and animals are ubiquitous members of coastal communities in nearly all marine systems. Such organisms move passively in response to flow as water moves past them. However, the full effects of this motion, and in particular the way it influences an organism's vulnerability to flow-driven disturbance, is poorly understood. Traditionally, the view has been that a compliant construction enhances the ability of sessile plants or animals to cope structurally with time-varying water motion. However, more recent research has noted that passive movement in flow can also have subtler consequences. For instance, an attached organism that is swept back and forth by ocean waves acquires momentum, and this momentum can impose a subsequent inertial force when the mass of the organism is eventually decelerated upon reaching the limits of its range of motion. Such complexities emphasize the need for a more complete and consistent examination of the biomechanical and survivorship implications of flexibility for intertidal and subtidal organisms. Without these further examinations, attempts to develop quantitative and mechanistic predictions of the mortality consequences of flow (long recognized as a dominant agent of disturbance and as a critical factor influencing population dynamics in these communities) will remain ineffective. Meeting this need is the goal of the proposed study.Research efforts will focus on measuring real-time forces applied to flexible organisms in the field and comparing those forces to quasi-static estimates based on hydrodynamic shape factors (drag coefficients determined previously for the same sample individuals) and simultaneously recorded flows. Differences between actual and quasi-static time series of force will then be used to quantify the way in which the passive motion that intrinsically accompanies organism flexibility alters applied force. Multiple sets of recordings will be conducted within three distinct fluid-dynamical "realms" on the shore (subtidal, submerged intertidal, and regions subjected to direct wave impingement where organisms are emergent between waves). Laminarian kelps, including the ecologically important Macrocystis pyrifera, Nereocystis luetkeana, Egregia menziesii, and Alaria marginata will be employed as focal species.Results will be compiled and expressed in terms of underlying nondimensional parameters that together govern organismal dynamics across species and the three shoreline realms. Relationships among the nondimensional parameters will be examined quantitatively and synthesized overall to develop a general, coherent framework that defines how flexibility influences imposed force across a wide range of organisms living across a full spectrum of flow environments. This ensuing biomechanical framework will then be used to predict actual rates of flow-mediated mortality for kelps in the field as a function of the nondimensional parameters, and these predicted rates will be compared to the observed rates across tagged individuals of a spectrum of sizes, growing in a range of water depths and heights on the shore.Broader impacts: The activities proposed here have important implications for predicting the response of critically important community players (Macrocystis provides necessary habitat for hundreds of coastal species, including many with economic and recreational value) to ongoing shifts in wave regimes due to global climate change. Biomechanical insights will also inform issues of coastal engineering where kelps affect nearshore currents and sediment transport, and the field of biomimetics. In addition, there are strong educational/partnership implications, since undergraduate and graduate assistants, both paid and volunteer, will be involved intimately in core experiments and analyses. Such opportunities will provide for rigorous, team research experiences that foster the scientific development of students early in their careers. Results of the project will be further conveyed to wider audiences via the incorporation of results into formal university courses, books written for the general scientific arena, and through existing ties with public-sector agencies. Basic intellectual exchange and discourse will be enhanced through a close collaboration that brings together scientists and labs from three institutions.

科学背景和知识价值：机械灵活的底栖植物和动物是几乎所有海洋系统中沿海社区的普遍成员。当水流过它们时，这些生物被动地响应水流。然而，这种运动的全部影响，特别是它影响生物体对流动驱动扰动的脆弱性的方式，知之甚少。传统的观点认为，顺应性结构增强了固着植物或动物在结构上科普随时间变化的水运动的能力。然而，最近的研究指出，心流中的被动运动也会产生更微妙的后果。例如，被海浪来回扫过的附着生物体获得动量，并且当生物体的质量在达到其运动范围的极限时最终减速时，该动量可以施加随后的惯性力。这种复杂性强调需要一个更完整和一致的检查的生物力学和生存的影响，灵活性的潮间带和潮下带生物。 没有这些进一步的检查，试图发展流动的死亡率后果的定量和机械预测（长期被认为是一个主要的干扰因素，并作为一个关键因素影响人口动态在这些社区）将仍然是无效的。 满足这一需求是拟议研究的目标，研究工作将侧重于测量现场柔性生物体所受的实时力，并将这些力与基于流体动力学形状因子（先前为相同样本个体确定的阻力系数）和同时记录的流量的准静态估计值进行比较。 实际和准静态力的时间序列之间的差异，然后将被用来量化的方式，其中的被动运动，内在地伴随着生物体的灵活性改变施加的力。 将在海岸上的三个不同的流体动力学“领域”（潮下带、淹没的潮间带和受到波浪直接冲击的区域，其中生物体在波浪之间出现）内进行多组记录。海带，包括生态上重要的Macrocystis pyrifera，Nereocystis luetkeana，Egregia menziesii和Alaria marginata.Results将被用作focal species.Results将被编译和表达的基本无量纲参数，共同管理跨物种和三个海岸线领域的生物动态。无量纲参数之间的关系将进行定量研究和综合整体开发一个通用的，连贯的框架，定义如何灵活性的影响施加的力量在广泛的生物体生活在一个完整的频谱的流动环境。随后的生物力学框架将用于预测作为无量纲参数的函数的该领域中的海带的流动介导的死亡率的实际速率，并且这些预测的速率将与在海岸上的一系列水深和高度中生长的一系列尺寸的标记个体之间观察到的速率进行比较。这里提出的活动对预测社区中至关重要的参与者的反应具有重要意义（Macrocystis为数百种沿海物种提供了必要的栖息地，包括许多具有经济和娱乐价值的波浪）与全球气候变化引起的波浪状态的持续变化有关。生物力学的见解也将告知沿海工程的问题，海带影响近岸水流和沉积物运输，以及仿生学领域。此外，有很强的教育/伙伴关系的影响，因为本科生和研究生助理，无论是有偿和志愿者，将密切参与核心实验和分析。这样的机会将提供严谨的团队研究经验，促进学生在职业生涯早期的科学发展。将通过将项目成果纳入正式的大学课程、为一般科学竞技场编写的书籍以及通过与公共部门机构的现有联系，向更广泛的受众进一步传达项目成果。通过将来自三个机构的科学家和实验室聚集在一起的密切合作，将加强基本的知识交流和讨论。