Collaborative Research: Turbulence and Suspension Feeding - a New Approach using the Lobate Ctenophore Mnemiopsis Leidyi

捕食者对猎物的选择、摄取以及最终的营养影响是由发生在生物体层面的一系列事件决定的--捕食者猎物与其环境之间的个体相互作用。此外，由于大多数捕食者-猎物的相互作用发生在流动的流体中，在流体动力学的背景下观察和量化捕食者-猎物的相互作用是至关重要的。对自然环境中营养模式的成功预测受到以下能力的限制：1)直接观察湍流对中上层生物摄食的影响；2)了解湍流环境中动物-流体相互作用的机制基础；以及3)将静水实验室研究的定量观察与自然联系起来。这些局限性普遍存在于海洋生态学更大范围内的营养交换研究中。最新的技术进步，以及Co-Pis的综合专业知识，使人们能够有意义地研究湍流对臭名昭著的侵入性分叶鞭毛虫Mnformopsis leidyi摄食的影响。马尼普斯是一种脆弱的胶状捕食者，它使用层流进食电流来诱捕猎物。使用非常有效的摄食策略，浮游动物的现存量和浮游动物的总生物多样性减少，浮游植物的现存量通过营养级联增加。然而，与许多悬浮喂食器一样，线虫产生的馈电电流可能容易受到环境流动的水动力干扰。事实上，湍流事件可能会改变诸如毛细管藻等分叶毛虫的行为、分布和猎物选择。该物种是一种理想的模式生物，可以用来确定湍流影响生态影响浮游悬浮摄食者营养交换模式的机制。这项研究采用实验室和现场相结合的方法，在生物体水平上进行量化，将确定湍流对线虫的取食机制和捕食者-猎物相互作用的影响。了解这些湍流效应如何转化到群落水平将通过现场采样技术来完成，该技术将自然湍流水平与摄食率、猎物选择和捕食影响联系起来。这种方法超越了目前的实验室和模型研究，有可能建立明确的因果关系。智力上的优点：这项研究将：1)直接量化湍流对原位捕食者-猎物相互作用的影响；2)提供对影响重要入侵海洋物种生态影响的关键变量的机械理解；以及3)开发一种新的方法来研究实验室和现场的小规模物理-生物相互作用。了解湍流如何影响分叶鞭毛虫的摄食，无论是在生物体的规模上，还是在生态学上都是有价值的。这里开发的方法也可以应用于各种其他以湍流为主的情况(例如，锋面混合、动物-海洋雪相互作用)或其他生物(其他浮游生物、海底-水柱交换)。在所有情况下，结果都取决于小规模的物理-生物过程。广泛的影响：本科生(5名)、研究生和合作伙伴将作为一个团队在实地和实验室工作，为所有参与者提供研究各个方面的经验。加州理工学院(加州理工大学新生暑期学院研究计划)的一个项目将促进未被充分代表的本科生的参与，该项目旨在为全国各地校园的少数族裔学生提供研究机会。这位加州理工学院的合作者将继续担任该项目的教师顾问。莱氏隐杆藻是一种入侵物种，可以极大地影响半封闭水体中的食物链，是国际上广泛关注的焦点。补救措施一直是正在进行的讨论(和实验)的主题；因此，这项研究的结果将及时传达给国际科学界。此外，还将利用与公众科学教育有关的媒体(如公共广播公司的生命形态系列、新英格兰水族馆的奇幻水母展览)的联系来传达新的发现。

Prey selection, intake and, ultimately, the trophic impact of predators are determined by a succession of events that occur at the organismal level -- individual interactions among predators prey, and their environments. Furthermore, because the majority of predator-prey interactions occur in moving fluids, it is critical to observe and quantify predator-prey interactions within a hydrodynamic context. Successful predictions of trophic patterns in natural settings are limited by the ability to: 1) observe directly the effects of turbulence on feeding in pelagic organisms; 2) understand the mechanistic bases of animal-fluid interactions in turbulent environments; and 3) relate quantitative observations from still-water laboratory studies to nature. These limitations are pervasive in studies of trophic exchange within the larger scope of marine ecology. Recent technological advances, and the combined expertise of the Co-PIs, enables meaningful studies of the influence of turbulence on feeding by the notoriously invasive lobate ctenophore, Mnemiopsis leidyi. Mnemiopsis is a delicate gelatinous predator which uses a laminar feeding current to entrain and capture prey. Using a remarkably effective feeding strategy, zooplankton standing stocks and overall zooplankton biodiversity are reduced, and standing stocks of phytoplankton are increased via a trophic cascade. Like many suspension feeders, however, the feeding current produced by Mnemiopsis may be vulnerable to hydrodynamic disruption by ambient flows. In fact, turbulent events may change the behavior, distribution and prey selection of lobate ctenophores such as Mnemiopsis. This species is an ideal model organism to determine the mechanisms by which turbulence affects trophic exchange patterns of ecologically influential planktonic suspension feeders. Involving a combination of laboratory and in situ methods to quantify, at the organismal level, this study will determine effects of turbulent flows on the feeding mechanics and predator-prey interactions of Mnemiopsis. Understanding how these turbulent effects translate to the community level will be accomplished via in situ sampling techniques that relate natural turbulence levels to ingestion rates, prey selection and predatory impact of Mnemiopsis in the field. This approach extends beyond current laboratory and modeling studies, with the potential of establishing clear cause-and-effect relationships.Intellectual Merit: This research will: 1) directly quantify turbulent effects on in situ predator-prey interactions; 2) provide mechanistic understanding of key variables influencing the ecological impact of an important invasive marine species; and 3) develop a novel approach for studying small-scale physical-biological interactions both in the laboratory and in the field. Knowing how turbulence affects feeding in lobate ctenophores is valuable at the scale of the organism, as well as ecologically. The approach developed here also may be applied to a variety of other turbulence-dominated situations (e.g., mixing at fronts, animal-marine snow interactions) or to other organisms (other plankton, benthic-water column exchanges). In all cases, the outcomes depend upon small-scale physical-biological processes.Broader Impacts: Undergraduates (5), the graduate student, and the Co-PIs will work as a team in both the field and the laboratory, providing all participants with experience in every aspect of the research. The participation of underrepresented undergraduates will be facilitated through a program at Caltech (Freshmen Summer Institute Research Program) aimed at providing research opportunities to minority students from campuses across the nation. The Caltech Co-PI will continue his role as faculty advisor to this program. An invasive species that can dramatically affect the food chain within semi-enclosed bodies of water, Mnemiopsis leidyi is the focus of broad international interest. Remediation has been the subject of ongoing discussions (and experiments); therefore, results of this research will be communicated to the international scientific community in a timely fashion. In addition, contacts with media (e.g., PBS Shape of Life series, Fantastic Jellies exhibit at the New England Aquarium) involved in scientific education of the general public will be used to convey new findings.