RUI: Using Direct Evidence to Determine the Energetic and Ecological Significance of Dissolved Organic Matter (DOM) for the Bryozoan Bugula Neritina

从最简单的细菌到最复杂的多细胞动物，所有生物都需要能量来维持代谢、生长和繁殖。因此，毫不奇怪，各种各样的机制已经进化出来，以获得进行这些重要过程所需的能量。在水生生物中发展起来的一个这样的系统涉及直接从周围介质中运输和利用溶解有机物（DOM）的细胞。该项目的工作将为DOM对海洋无脊椎动物的生态和能量作用提供急需的直接证据。目前大多数关于海洋无脊椎动物使用DOM的研究仅限于基于代谢消耗和从溶解化合物的摄取速率计算的DOM潜在贡献的比较的间接证据。尽管这种方法在确定DOM的理论贡献方面很有用，但它并不能直接描述对动物能量预算的实际贡献。需要一种基于比较存在和不存在DOM时动物代谢消耗的更直接的方法。本研究旨在通过一系列的实验室和野外实验，研究苔藓虫在幼虫游泳和变形过程中DOM的有效性如何影响生态相关参数，如幼虫游泳时间、变形能力、变形后的大小、成虫生长速度以及繁殖的开始和数量，从而建立这一理论。此外，将通过放射自显影技术建立DOM进入幼虫组织和早期后变质阶段的直接证据。这些数据将提供如何以及何时使用运输化合物的见解（例如，用于游泳，变态，早期幼年生长）。综上所述，这些实验将为DOM对无脊椎动物营养生物学的实际贡献提供直接证据，大大增加了我们目前对DOM生态和能量重要性的理解。

All organisms ranging from the simplest bacterium to the most sophisticated multicellular animal need energy for metabolic maintenance, growth, and reproduction. It is thus not surprising that a wide variety of mechanisms have evolved for acquiring the energy needed to carry out these vital processes. One such system that has developed among aquatic organisms involves cellular transport and utilization of dissolved organic matter (DOM) directly from the surrounding medium. The work from this project will add much needed direct evidence on the ecological and energetic role of DOM for marine invertebrate animals. Most of the current studies examining use of DOM by marine invertebrates are limited to indirect evidence based on comparisons of metabolic expenditure and potential contribution of DOM calculated from uptake rates of dissolved compounds. Although this approach is useful in determining the theoretical contribution of DOM, it does not directly characterize the realized contribution to an animal's energy budget. A more direct approach based on comparisons of metabolic expenditure of animals in the presence versus absence of DOM is needed. The proposed work seeks to establish this for the bryozoan Bugula neritina through a series of laboratory and field experiments examining how the availability of DOM during larval swimming and metamorphosis effects ecological relevant parameters such as, larval swimming duration, metamorphic competence, size after metamorphosis, adult growth rate, and onset and amount of reproduction. In addition, direct evidence for incorporation of DOM into larval tissues and those of early post-metamorphic stages will be established through autoradiographic techniques. These data will provide insight into how and when the transported compounds are being used (e.g., for swimming, metamorphosis, early juvenile growth). Taken together, the proposed experiments will provide direct evidence on the realized contribution of DOM to the nutritional biology of invertebrates, adding significantly to our current understanding of the ecological and energetic importance of DOM.