Collaborative Research: Chemical Orientation in Turbulent Environments Above Natural Stream Substrates: The Role of Bed Roughness and Turbulence Structure on Search Mechanisms

这项合作提案描述了将溪流水动力学、气味信号的湍流传输以及小龙虾的感觉生态和行为联系起来的研究。小龙虾使用水传播的化学信号(“气味羽毛”)作为导航信号，以确定食物、洞穴或配偶的位置，并避开捕食者。气味羽流的时空变异性(“结构”)的性质取决于水动力条件，而水动力条件又取决于水流的物理特性。这项拟议研究的目标是了解小龙虾是如何利用气味羽毛来定位水下物体的。特别是，我们计划研究小龙虾在不同水动力条件下的导航行为如何变化(与不同类型的水系基质材料有关)。通过将注意力集中在不同底物类型上气味结构和相关定向行为的变化上，我们希望深入了解动物使用的特定算法和信息线索。最终，从拟议的研究中获得的知识可以用于设计机器人车辆，以搜索危险的水下物体，或保护受管理的生态系统中的小龙虾栖息地。在环境方面，小龙虾是许多溪流栖息地的关键物种，了解影响它们行为的物理、生物和化学因素将有助于更广泛地了解溪流生态以及人类对溪流生态的影响。特别是，对溪流栖息地如何影响化学物质分布的详细了解将提供必要的信息，不仅有助于理解小龙虾和溪流生态学，还将有助于阐明溪流中污染传输背后的物理机制及其对溪流生态系统的可能影响。这项建议中概述的工作是生物学家和工程师之间的合作努力，将导致研究生和本科生的跨学科培训。此外，通过开发高速和精细的不同自然流动状态下的化学浓度的三维测量，将取得新的技术进步。这些技术的发展和量化将使从海洋学到环境工程的广泛领域受益。

This collaborative proposal describes research that links stream hydrodynamics, turbulent transport of odor signals, and the sensory ecology and behavior of the crayfish Orconectes rusticus. Crayfish use water-borne chemical signals ("odor plumes") as navigational cues for locating food, burrows, or mates, and for avoiding predators. The nature of the spatial and temporal variability ("structure") of the odor plumes depends on the hydrodynamic conditions, which, in turn, depends on the physical characteristics of the stream. The goal of the proposed research is to understand how crayfish use odor plumes to locate underwater objects. In particular, we plan to investigate how the crayfish navigational behavior varies under different hydrodynamic conditions (associated with different types of stream substrate materials). By focusing our attention to the changes in odorant structure and associated orientation behavior over different substrate types, we hope to gain insight into the specific algorithms and information cues used by the animals. Ultimately, the knowledge gained from the proposed study could be used to design robotic vehicles to search for dangerous underwater objects, or to protect crayfish habitat in managed ecosystems. Environmentally, crayfish are keystone species for many stream habitats and understanding the physical, biological, and chemical factors that influence their behavior will lead to a broader understanding of stream ecology and the human impact on stream ecology. In particular, detailed knowledge of how stream habitats influence the distribution of chemicals will provide the information necessary to understand not only crayfish and stream ecology, but will help elucidate the physical mechanisms behind pollution transportation in streams and their possible impact on stream ecosystems.The work outlined in this proposal is a collaborative effort between a biologist and engineer that will lead to cross-disciplinary training of both graduate and undergraduate students. In addition, new technical advances will be achieved through the development of high-speed and fine-scale three-dimensional measurements of chemical concentrations in different natural flow regimes. The development and quantification of these techniques will benefit a wide array of fields from oceanography to environmental engineering.