Collaborative Research: Deep-sea larvae as grazers in the midwater microbial loop

虽然通常认为后生动物(多细胞)不直接以微生物环路为食，但有纤毛的无脊椎动物幼虫足够小，可以直接利用这种食物来源。每年底栖无脊椎动物产生数十亿条幼虫，与以甲壳类浮游动物为主的浅水水域相比，中水深处的浮游生物所占比例可能更高。深海幼虫的食物来源在很大程度上仍然没有解决。在初步研究中，在低于最大叶绿素深度的天然水中饲养的半深海棘皮幼虫消耗了大量的蓝藻，蓝藻是如此之小，以至于它们不应该轻易沉入这些深度。这意味着这些深海幼虫可能会积极地向上游到较浅的深度以达到觅食的目的。在这个项目中，研究人员将研究墨西哥湾和巴哈马群岛幼虫形态的垂直分布及其潜在的微生物食物来源，特别是蓝藻、微真核生物和异养细菌作为深海幼虫迁徙食物来源的潜在作用。一个多学科的团队将测量幼虫的新陈代谢、游泳和觅食活动，以及深水中潜在食物生物的生理状态。经验数据将被纳入一个能量学模型，该模型预测起源于半深海的幼虫个体发育迁移到真光区的可能性。为了保持他们过去在学院和K-12级别的外展和教育记录，调查人员将为实践中的多学科研究的研究生和本科生提供广泛和密集的学习机会。一门名为深海底栖动物生物学的大学课程将在海上教授，就像之前NSF赞助的项目期间一样。邮轮将拥有互联网组件，通过直接从邮轮发布的网络帖子来激发人们对科学冒险的兴奋。调查人员还将继续参与外联工作，包括定期举行一系列公开讲座，以及为本科生和以少数族裔为主的机构提供研讨会演讲者的大学项目。

Although it is generally assumed that metazoan (multicellular) animals do not feed directly on the microbial loop, ciliated invertebrate larvae are small enough to exploit this food source directly. Billions of larvae are produced each year by benthic invertebrates, and probably comprise a higher proportion of the plankton at midwater depths than in shallow waters dominated by crustacean zooplankters. The food sources for deep-sea larvae remain largely unresolved. In preliminary studies, bathyal echinoderm larvae reared in natural water from below the deep chlorophyll maximum consumed significant numbers of cyanobacteria, organisms so small that they should not easily sink into those depths. The implication is that these deep-sea larvae may swim actively up to shallower depths for the purpose of feeding. In this project, the investigators will examine the vertical distributions of larval forms and their potential microbial food sources in the Gulf of Mexico and the Bahamas, focusing especially on the potential role of cyanobacteria, picoeukaryotes, and heterotrophic bacteria as food sources for migrating deep-sea larvae. A multidisciplinary team will measure larval metabolism, swimming and feeding activity; and the physiological status of potential food organisms in deep water. Empirical data will be incorporated into an energetics model that predicts the likelihood of ontogenetic migration to the euphotic zone for larvae originating at bathyal depths. In keeping with their past record outreach and education at both the college and k-12 levels, the investigators will provide extensive and intensive learning opportunities for graduate and undergraduate students in hands-on multidisciplinary research. A college course, Biology of the Deep-sea Benthos, will be taught at sea, as it has been during previous NSF sponsored projects. Cruises will have internet components that will engender excitement in the adventure of science through web postings directly from the cruises. The investigators also will continue their involvement with outreach efforts including a regular public lecture series and a university program that provides seminar speakers to undergraduate and predominantly minority institutions.