Swimming and Vulnerability in Pelagic Development

早期游泳在浮游生物的发展提供了一个系统，以测试假设的优势，水柱，而不是底栖生物作为栖息地的动物在他们的生活史的早期。各种海洋动物将卵释放到水中，以发育为早期游泳的孤立的浮游胚胎，通常仍处于胚胎阶段。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。底栖胚胎得到更大的父母的保护，进一步表明，底栖生物是一个危险的地方，为孤独的胚胎。这个项目将回答三个问题。早期的游泳是否消除了底栖捕食者的早期胚胎阶段，尽管湍流混合？早期游泳是否会减少常见的中上层捕食者的捕获？早期阶段的动物是否比底栖食肉动物更容易受到中上层动物的伤害？这些问题将通过实验室和现场研究相结合来解决，这些研究分析了湍流和非湍流条件下的下沉和游泳速度。 由于湍流会使游泳者偏离垂直方向，因此实验还将比较湍流中的垂直偏差与静水中的垂直偏差，以估计湍流中重新定向到垂直方向的有效性。温度通常随深度而变化，因此该项目还将测量温度对下沉和游泳速度的影响。 比下沉更快的游泳可能会增加与伏击捕食者的遭遇，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的湍流产生的剪切进行比较。游泳者在较小的距离取代水，从而产生一个较小的信号捕食者比被动下沉的假设，也将进行测试。 在胚胎开始游泳之前和之后定量捕获和摄取胚胎将测试游泳减少每次遭遇成功捕获的假设。捕食者将包括鱼苗、桡足类、水母和栉水母。将把关于预泳和游泳阶段脆弱性的结果与关于浮游和底栖捕食者的丰度和清除率的公布数据相结合，以检验以下假设：处于发育早期阶段的动物在水柱中比在底部附近更安全。 两名研究生将在他们的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.