Exchange of material across the nearshore region, extending from the shoreline to a few kilometers offshore, determines the concentrations of pathogens and nutrients near the coast and the transport of larvae, whose cross-shore positions influence dispersal and recruitment. Here, we describe a framework for estimating the relative importance of cross-shore exchange mechanisms, including winds, Stokes drift, rip currents, internal waves, and diurnal heating and cooling. For each mechanism, we define an exchange velocity as a function of environmental conditions. The exchange velocity applies for organisms that keep a particular depth due to swimming or buoyancy. A related exchange diffusivity quantifies horizontal spreading of particles without enough vertical swimming speed or buoyancy to counteract turbulent velocities. This framework provides a way to determinewhich processes are important for cross-shore exchange for a particular study site, time period, and particle behavior.

中文翻译：

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近岸区域浮游生物、污染物和颗粒的交换


近岸区域（从海岸线延伸到离岸几公里）的物质交换决定了海岸附近病原体和营养物质的浓度以及幼虫的运输，幼虫的跨岸位置影响扩散和补充。在这里，我们描述了一个估计跨岸交换机制相对重要性的框架，包括风、斯托克斯漂移、离岸流、内波以及昼夜加热和冷却。对于每种机制，我们将交换速度定义为环境条件的函数。交换速度适用于由于游泳或浮力而保持特定深度的生物体。相关的交换扩散率量化了颗粒的水平扩散，而没有足够的垂直游动速度或浮力来抵消湍流速度。该框架提供了一种方法来确定哪些过程对于特定研究地点、时间段和粒子行为的跨岸交换很重要。