Collaborative Research: Effects of Flow on Feeding Behavior and Growth Rate of Interface-Feeding Benthos: Size-Dependent Changes and Recruitment Bottlenecks

Hentschel 0000951以沉积物或悬浮颗粒为食的物种的幼鱼面临着从丰富的幼虫饮食（浮游生物或蛋黄）到贫乏的成年饮食（沉积物相关有机物）的过渡。体型小进一步限制了消化和觅食能力，可能限制了幼鱼专门捕食沉积物或底栖边界层中相对不稳定的食物（例如底栖硅藻、植物碎屑、富含有机物的絮状物、动物猎物）。最近的研究揭示了几种界面摄食多毛类动物饮食的大小依赖性变化。虽然改变饮食的证据是明确的，蠕虫的进食活动的方式转变，作为青少年成长为成人是没有解决的。对于在沉积物-水界面觅食的物种和已知的适应性切换之间的存款喂养和悬浮液喂养的水动力条件，更频繁的悬浮液喂养在少年阶段是一个可能的手段，小蠕虫可能会增加他们的饮食质量和增长速度。这种大小依赖的转变，在喂养行为和生态位可能有戏剧性的影响，人口和社区动态。如果悬浮液喂养的主要手段，少年克服特定大小的食物限制，栖息地的水动力学特性将强烈影响少年的生长和招聘率的生殖，成人阶段。虽然水流对扩散和幼体定居的影响已受到相当大的关注，但水流对幼体生长的影响是一个相对未研究的生物-水流相互作用，可能会像水流对扩散和定居的影响一样显著地影响底栖动物种群和群落的结构和动态。没有测量与大小有关的摄食行为和生长率与水流的关系; 2）现有数据表明，在若干spionids中，饮食变化与大小有关，食物补充存在瓶颈; 3）spionids是许多底栖生物群落的丰富成员，在食物网和地球化学过程中发挥核心作用。为了检验这一假设，即青少年往往悬浮饲料比成年人更频繁，个体的大小依赖的摄食行为将在实验室水槽中观察到各种流量和食物条件下。要量化的营养后果的大小依赖的变化，摄食行为，生长率的不同大小的类将被测量下选定的流量和食物的治疗，在四个相同的，反向旋转的环形水槽，将被设置为流体动力学不同的中生态系统。为了揭示与种内体型变化有关的摄食力学和行为的物理限制，将在小体积水槽中量化颗粒捕获的速率和效率。为了更好地将实验室实验结果外推到密集的野外种群，将测试密度对幼鱼生长速率和颗粒摄入的影响。洞察之间的联系喂养行为和力学，增长率，颗粒特性，和流速将提供一个多方面的和机械的理解之间的关系栖息地的水动力制度和增长率和招聘到成年spionid种群。在教育和人力资源方面，合作的努力结合和扩大了博士后助理，初级教员，和终身教职导师此外，整合行为观察和涉及生态，物理和生物化学参数的操纵实验提供了一个理想的格式，介绍本科生在一个主要的研究型大学和一个小的文科学院的跨学科研究。

Hentschel 0000951Juveniles of species that, as adults, feed on deposited or suspended particles face a transition from a rich larval diet (plankton or yolk) to a poor adult one (sediment-associated organics). Small body size further imposes digestive and foraging limitations that probably constrain juveniles to specialize on relatively labile foods in the sediment or benthic boundary layer (e.g. benthic diatoms, phytodetritus, organic-rich flocs, animal prey). Recent research has revealed size-dependent changes in the diets of several interface-feeding polychaetes. Although evidence of changing diets is clear, the ways in which worms' feeding activities shift as juveniles grow to adults is unresolved. For species foraging at the sediment-water interface and known to facultatively switch between deposit feeding and suspension feeding in response to hydrodynamic conditions, more frequent suspension feeding during the juvenile stage is a likely means by which small worms might increase the quality of their diet and their rate of growth. Such a size-dependent shift in feeding behavior and niche could have dramatic implications for population and community dynamics. If suspension feeding were the dominant means by which juveniles overcome size-specific food limitation, a habitat's hydrodynamic characteristics would strongly affect rates of juvenile growth and recruitment to the reproductive, adult stage. While flow's influence on dispersal and larval settlement has received considerable attention, flow-related effects on juvenile growth are a relatively unstudied organism-flow interaction that might impact the structure and dynamics of benthic populations and communities as significantly as flow's effects on dispersal and settlement.The study focuses on four species of spionid polychaetes because 1) although spionids are the best studied interface feeders, size-dependent feeding behavior and growth rates have not been measured in relation to flow; 2) existing data point to size-dependent diet changes and food-related recruitment bottlenecks in several spionids; and 3) spionids are abundant members of many benthic communities, playing central roles in food webs and geochemical processes. To test the hypothesis that juveniles tend to suspension feed more often than adults, the size-dependent feeding behavior of individuals will be observed in a laboratory flume under a variety of flow and food conditions. To quantify the nutritional consequences of size-dependent shifts in feeding behavior, growth rates of different size classes will be measured under selected flow and food treatments in four identical, counter-rotating annular flumes that will be set up as hydrodynamically distinct mesocosms. To reveal physical constraints on feeding mechanics and behavior in relation to intraspecific body-size variations, rates and efficiencies of particle capture will be quantified in a small-volume flume. To better extrapolate results from lab experiments on individuals to dense field populations, density--dependent effects on juvenile growth rate and particle ingestion will be tested. Insight into linkages among feeding behaviors and mechanics, growth rates, particle characteristics, and flow speed will provide a multifaceted and mechanistic understanding of the relationships between a habitat's hydrodynamic regime and the rates of growth and recruitment to adulthood in spionid populations.In terms of educational and human resources, the collaborative effort combines and broadens the expertise of a postdoctoral associate, a junior faculty member, and a tenured faculty mentor. In addition, integrating behavioral observations and manipulative experiments involving ecological, physical and biochemical parameters provides an ideal format to introduce undergraduates to interdisciplinary research at both a major research university and a small liberal-arts college.