Dispersal, retention, and population connectivity are impacted by current regime and the behaviors that drive larval distribution, so understanding both is key to informing restoration of native species like the Olympia oyster (Ostrea lurida) across its range in western North America. This study explores the relationships between several factors (temperature, [chl a], larval size, tidal stage, and estimated current speed) and Olympia oyster larval vertical distributions in Fidalgo Bay (48.4828, − 122.5811), a shallow, tidally flushed bay in the Salish Sea. Olympia oyster larvae collected from four depths over the tidal cycle from July 11–14, 2017, were ~ 20% deeper near slack tide and shallower during the faster parts of both ebb and flood, with a threshold for this transition around an estimated 25 cm s⁻¹. This pattern does not suggest tidally timed migrations as has been shown in another population of Olympia oysters, nor can this pattern be totally explained by passive processes. Larvae did not cluster at depths with specific temperatures or [chl a] but there was a difference in larval size between surface and bottom waters, with older, larger larvae more common at the bottom. Fidalgo Bay does not exhibit two-way flow or strong vertical shear, so vertical distribution of larvae likely has little effect on transport in this system but might in other similarly shallow habitat areas with higher stratification that are target restoration sites in the Salish Sea. These results add to the growing number of studies that show location-specific differences in larval vertical distribution and behavior within taxa and underscore the importance of integrating local hydrodynamics into predictions of bivalve larval transport.

分散性，保留性和种群连通性受到当前制度和驱动幼虫分布的行为的影响，因此了解两者都是为恢复北美洲西部范围内的奥林匹亚牡蛎（Ostrea lurida）等原生物种的恢复的关键。这项研究探索了Fidalgo湾（48.4828，-122.5811）中的一个浅潮汐冲刷湾的几个因素（温度，[chl a]，幼体大小，潮汐阶段和估计的当前速度）与奥林匹亚牡蛎幼体垂直分布之间的关系。萨利什海。在2017年7月11日至14日的潮汐周期中，从四个深度采集的奥林匹亚牡蛎幼体在退潮和潮汐较快的时期内，在潮汐附近的深度约为20％，在较浅的地方则较浅，此过渡的阈值约为25厘米s^-1。这种模式并不意味着潮汐定时迁移，正如在其他奥林匹亚牡蛎种群中所显示的那样，也不能用被动过程完全解释这种模式。幼虫并没有在特定温度或深度下聚集[chl a]，但是地表水和底水之间的幼虫大小有所不同，年龄较大的较大幼虫在底部更为常见。菲达尔戈湾没有双向流动或强烈的垂直剪切作用，因此幼虫的垂直分布可能对该系统的运输几乎没有影响，但可能会在其他类似浅层栖息地的浅层栖息地（这些盐是萨利什海的恢复地点）。