Swimming and Vulnerability in Pelagic Development

浮游生物发育的早期游泳提供了一个系统，用来检验关于水柱而不是底栖动物作为动物生活史早期栖息地的优势的假说。不同的海洋动物将卵释放到水中，发育成单独的浮游胚胎，这些胚胎很早就会游泳，通常还处于胚胎阶段。早期游泳阶段的广泛存在表明，水柱在早期和脆弱的生活史阶段作为栖息地的优势。沉积在底部的孤立胚胎可能面临更大的风险。底栖生物胚胎得到更多的父母保护，进一步表明底栖动物是孤立胚胎的危险场所。这个项目将回答三个问题。早期游泳是否消除了海底捕食者的早期胚胎阶段，尽管它们处于动荡的混合状态？早期游泳会减少普通远洋捕食者的捕获量吗？早期阶段的动物是不是比底栖食肉动物更不容易受到中上层捕食者的伤害？这些问题将通过实验室和现场研究相结合的方式来解决，这些研究将分析在湍流和非湍流条件下的下沉和游泳速度。因为湍流会使游泳者远离垂直方向，所以实验还将比较湍流中的垂直偏差和静止水中的垂直偏差，以评估在湍流中重新定向到垂直方向的有效性。温度通常随着深度的变化而变化，所以这个项目还将测量温度对下沉和游泳速度的影响。比下沉更快的游泳速度可能会增加与埋伏捕食者的接触，因此下沉和游泳的速度将与捕食者相对于水的速度进行比较，并与捕食者感知体积内预测的湍流产生的剪切进行比较。游泳者在较短的距离内排出水，从而向捕食者发出的信号比被动下沉的人产生的信号更小的假设也将得到检验。量化胚胎开始游泳前后的捕获和摄取将检验这样一个假设，即游泳会减少每次相遇的成功捕获。捕食者将包括鱼类幼虫、桡足类、水母和鞭毛虫。关于潜水期和游泳期脆弱性的结果将与已公布的关于中上层和底栖捕食者丰度和清理率的数据结合起来，以检验这样一个假设，即发育早期的动物在水柱中比在底部附近更安全地免受捕食。两名研究生将在他们的学位论文研究中参与拟议的研究，几名本科生将参与研究。

Early swimming in planktonic development provides a system for testing hypotheses on advantages of the water column rather than the benthos as a habitat for animals early in their life histories. Diverse marine animals release eggs into the water to develop as solitary planktonic embryos that swim early, often while still in embryonic stages. The widespread existence of early swimming stages suggests advantages of the water column as a habitat at early and vulnerable life history stages. Solitary embryos deposited on the bottom may be at greater risk. Benthic embryos receive greater parental protection, further indicating that the benthos is a risky place for solitary embryos. This project will answer three questions. Does early swimming remove early embryonic stages from benthic predators, despite turbulent mixing? Does early swimming reduce capture by common pelagic predators? Are animals at early stages less vulnerable to pelagic than to benthic predators?These questions will be addressed through a combination of lab and field studies that assay sinking and swimming velocities under turbulent and non-turbulent conditions. Because turbulence turns swimmers away from vertical orientation, experiments will also compare vertical bias in turbulence with vertical bias in still water to estimate effectiveness of reorientation to the vertical in turbulence. Temperature commonly varies with depth, so this project will also measure the effect of temperature on rates of sinking and swimming. Swimming faster than sinking could increase encounters with ambush predators, so velocities of sinking and swimming will be compared with those of predators relative to water, and to predicted turbulence generated shear within predators' perception volumes. The hypothesis that swimmers displace water at smaller distances, and thus produce a smaller signal to predators than do passive sinkers, will also be tested. Quantifying capture and ingestion of embryos before and after they begin to swim will test the hypothesis that swimming decreases successful captures per encounter. Predators will include fish larvae, copepods, medusae, and ctenophores. Results on vulnerability of preswimming and swimming stages will be combined with published data on abundance and clearance rates of pelagic and benthic predators to test the hypothesis that animals at early stages of development are safer from predation in the water column than near the bottom. Two graduate students will participate in the proposed research in their dissertation research, and several undergraduates will participate in the research.