RUI: Feeding by the ciliated larvae of marine invertebrates: effects of diverse particle capture mechanisms on feeding performance

许多海洋无脊椎动物的幼虫必须通过变态到幼年阶段来进食以促进发育。 这些觅食的幼虫以不同的方式捕捉悬浮的食物颗粒。实验室证据表明，不同的幼虫喂养机制可能会影响性能取决于颗粒类型。例如，棘皮动物的幼虫通过纤毛逆转进食，这是一种明显限制小颗粒（直径10 μ m）清除率的机制。 相比之下，软体动物幼虫饲料使用相反的纤毛带，这限制了较大颗粒（10 μ m）的清除率。由于悬浮食物颗粒的浓度会限制天然沃茨中的幼虫生长，并且由于天然颗粒的粒度分布随空间和时间而变化，因此特定摄食机制所施加的最大清除率可能会限制幼虫的生长速率和发育。因此，悬浮液喂养的幼虫的休眠期将延长，幼虫死亡率（由于捕食，或平流从合适的成年栖息地）增加，导致较低的招聘。通过这种方式，与特定幼虫喂养机制相关的性能限制可能会强烈影响种群动态。底栖无脊椎动物的种群动态模型中没有这种影响，主要是因为对它们的了解不够。为此，需要控制比较的纤毛幼虫的摄食能力，不同的摄食机制。本研究将检查幼虫的摄食能力，这些幼虫使用三种颗粒捕获机制之一（纤毛反转、反向带或反向带摄食和遇到大颗粒摄食的"混合"策略）收集食物，并且对于具有不同体型的幼虫（例如，在相反的带状进食中，轮足动物对面盘动物）。将检验三个主要假设。 (1)颗粒捕获机制/体型不同的幼虫在最大清除率或以高速率清除的颗粒尺寸谱方面也不同。实验室实验将涉及人工粒子，只是大小不同。(2)（1）中的假设差异也适用于自然粒子。 实验将测试半自然的猎物群落。(3)具有不同进食机制的幼虫将在特定的进食环境中表现最好（例如，由小颗粒相对于大颗粒占主导的那些）。将在实验操作的半天然食物方案中测试幼虫生长速率。智力优点：产生明确的，有计划的比较幼虫的性能作为一个功能的喂养机制，幼虫的身体形式，和颗粒类型，这项研究将提高认识的重要性，幼虫喂养机制在海洋无脊椎动物的种群动态。这项研究与生殖生物学、生态学和进化中的许多引人注目的问题有关，例如：颗粒食物类型的季节性变化如何影响具有特定摄食机制的幼虫的表现;这种联系如何与海洋无脊椎动物各种分类群的季节性生殖模式的进化有关;以及人类介导的海洋温度和化学变化（预计会改变潜在食物颗粒的大小范围）如何影响具有特定摄食机制的幼虫的表现？更广泛的影响：这一项目将在整合研究和教育以及增加代表性不足的群体对科学的参与方面产生更广泛的影响。大量的研究表明，密集的本科研究经验与随后在生物学等STEM职业中的参与和成功相关。该项目将为8 - 10名本科生和1名研究生提供此类经验，他们将得到该项目的支持。额外的学生研究人员将支持使用现有的计划在CSU长滩和星期五港实验室（UW），重点是加强生物学的文化多样性。研究助理将接受幼虫生物学和实验方法方面的培训，并将设计和执行直接有助于实现该提案目标的项目。他们将在科学会议上展示他们的成果，并作为同行评审论文的共同作者。作为该项目的一部分购买的设备也将用于重新设计几个CSU长滩本科课程的实验室。此外，作为该项目的一部分，PI和学生将创建一个免费提供的网站，汇编有关加州海洋无脊椎动物生殖和幼虫生物学的数据，这是该地区生物学家的独特和宝贵的资源。

Many marine invertebrate larvae must feed to fuel development through metamorphosis to the juvenile stage. These feeding larvae capture suspended food particles in diverse ways. Laboratory evidence suggests that different larval feeding mechanisms may affect performance depending on particle types. For example, larvae of echinoderms feed by ciliary reversal, a mechanism that apparently limits clearance rates on small particles (10 um diameter). In contrast, mollusk larvae feed using opposed bands of cilia, which limits clearance rates on larger particles (10 um). Because the concentration of suspended food particles can constrain larval growth in natural waters, and because the size distribution of natural particles varies over space and time, maximum clearance rates imposed by a particular feeding mechanism may restrict larval growth rates and development. As a result, the planktonic period of suspension-feeding larvae would be extended and larval mortality (due to predation, or advection from suitable adult habitat) increased, leading to lower recruitment. In this way, performance constraints associated with particular larval feeding mechanisms could strongly affect population dynamics. Such effects are missing from population-dynamic models of benthic invertebrates, largely because they are not well understood. Toward this end, controlled comparisons are needed of the feeding capabilities of ciliated larvae that differ in feeding mechanism. The present study will examine the feeding capabilities of larvae that gather food using one of three particle capture mechanisms (ciliary reversal, opposed band, or a "mixed" strategy of opposed band feeding and encounter feeding on large particles), and for larvae with distinct body forms (e.g., within opposed band feeding, trochophores vs. veligers). Three main hypotheses will be tested. (1) Larvae that differ in particle capture mechanisms/body form will also differ in either maximum clearance rates, or in the size spectrum of particles cleared at high rates. Laboratory experiments will involve artificial particles, varying only in size. (2) Hypothesized differences in (1) also hold for natural particles. Experiments will test semi-natural prey communities. (3) Larvae with different feeding mechanisms will perform best in specific feeding environments (e.g., those dominated by small particles versus large particles). Larval growth rates will be tested in experimentally manipulated, semi-natural food regimes. Intellectual merit: Yielding explicit, planned comparisons of larval performance as a function of feeding mechanism, larval body form, and particle type, this research would improve understanding of the importance of larval feeding mechanism in the population dynamics of marine invertebrates. This study is relevant to many compelling questions in reproductive biology, ecology and evolution, such as: how do seasonal changes in the types of particulate food affect the performance of larvae with particular feeding mechanisms; how might such linkages be related to the evolution of seasonal reproductive patterns in various taxa of marine invertebrates; and how might human-mediated shifts in ocean temperature and chemistry (predicted to alter the size spectrum of potential food particles) affect performance of larvae with particular feeding mechanisms? Broader impacts: This project will have significant broader impacts in integrating research and education, and in increasing the participation of underrepresented groups in science. Substantial research has shown that intense undergraduate research experiences are correlated with subsequent engagement and success in STEM careers like biology. This project will provide such experiences for 8-10 undergraduates and one graduate student, who will be supported by this project. Additional student researchers will be supported using existing programs at CSU Long Beach and the Friday Harbor Laboratories (UW) that focus on enhancing cultural diversity in biology. Research assistants will be trained in larval biology and experimental methods, and will design and carry out projects that contribute directly to addressing the proposal's goals. They will present their results at scientific meetings, and as coauthors of peer-reviewed papers. Equipment purchased as part of this project also will be used to redesign labs in several CSU Long Beach undergraduate courses. Moreover, as part of this project, the PI and students will create a freely available web site compiling data on the reproductive and larval biology of California marine invertebrates, a unique and valuable resource for biologists in the region.