Selective feeding by mucous-net filter feeders on the ocean's smallest organisms

粘液网滤食动物对海洋最小生物的选择性摄食

• 批准号: 1537201
• 负责人: Kelly Sutherland
• 金额: $ 23.95万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1537201&HistoricalAwards=false
• 关键词: Selective; feeding; mucous; net; filter

The surface of the ocean is dominated by microscopic plants and animals called picoplankton, which are at the base of the marine food web. Jelly-like animals called appendicularians specialize in feeding on these miniature organisms by filtering large quantities of water using nets made out of mucus. In the past, it was thought that appendicularians eat anything that passes through the mucous net, but new work shows that feeding may be selective. The most abundant group of microorganisms in the ocean, called SAR 11, seems to evade the appendicularian, while similar-sized photosynthetic microbes are captured. In this study, a series of lab and field experiments will be conducted in Oregon, USA, and Villefranche-sur-mer, France, to uncover the mechanisms for selectivity. The research will test the effect of particle shape (e.g. spherical vs. ellipsoidal), adhesion properties of particles to mucous meshes, and the role of hydrodynamics. It will focus on the cosmopolitan appendicularian Oikopleura dioica, an important grazer of picoplankton. Results will be important for understanding the role of mucous-net filter feeders in shaping the structure of the ocean's microbial community as well as biogeochemical cycling. The project will support an early-career faculty member, will provide training and mentoring for one PhD student and two undergraduates, involves collaboration with scientists in France and Israel, and will engage the public through exhibits and images to be displayed at the Hatfield Marine Science Visitor Center and Charleston Marine Life Center. Picoplankton occur at densities of up to a million per mL and numerically dominate the upper ocean prey field. Since appendicularians influence pico- and nano-particle flux through their high filtration rates and the production of mucous aggregates, selective grazing will have important ramifications for microbial loop dynamics and vertical flux. Therefore, this work will provide insights into the mechanisms governing bacterioplankton community structure in the upper ocean and increase understanding of microbial-metazoan food web interactions in both neritic and oceanic ecosystems. The specific goals of the project are to a) determine the role of flow morphology in regulating particle capture within the houses of free-swimming appendicularians using micro-Particle Image Velocimetry, b) determine the effect of particle shape on retention efficiencies by appendicularians, and compare this effect between synthetic and biological particles, and c) quantify particle adhesion to the mucous filtration apparatus in order to determine if picoplankton cell surface properties influence retention efficiencies by mucous-net filter-feeders.

海洋表面主要是被称为微浮游生物的微小植物和动物，它们处于海洋食物网的底部。被称为尾虫的水母状动物专门以这些微型生物为食，它们用粘液制成的网过滤大量的水。过去，人们认为阑尾虫会吃掉任何通过粘液网的东西，但新的研究表明，进食可能是有选择性的。海洋中最丰富的微生物群，称为SAR 11，似乎避开了尾虫，而类似大小的光合微生物被捕获。在这项研究中，将在美国俄勒冈州和法国维尔弗朗什进行一系列的实验室和实地实验，以揭示选择性的机制。该研究将测试颗粒形状（例如球形与椭球形）的影响，颗粒对黏液网的粘附特性以及流体动力学的作用。它将集中讨论世界性的尾尾鱼Oikopleura dioica，一种重要的浮游生物食草动物。研究结果对于理解黏液网滤食性动物在形成海洋微生物群落结构和生物地球化学循环中的作用具有重要意义。该项目将支持一名早期职业教师，为一名博士生和两名本科生提供培训和指导，与法国和以色列的科学家合作，并将通过在哈特菲尔德海洋科学游客中心和查尔斯顿海洋生物中心展示的展览和图像吸引公众。微浮游生物的密度高达每毫升100万，在数量上主宰着上层海洋的猎物场。由于尾虫通过其高过滤率和粘液聚集体的产生来影响微粒子和纳米粒子的通量，因此选择性放牧将对微生物环动力学和垂直通量产生重要影响。因此，这项工作将提供对上层海洋浮游细菌群落结构的控制机制的见解，并增加对浅海和海洋生态系统中微生物-后生动物食物网相互作用的理解。该项目的具体目标是：a)利用微粒子图像测速法确定流动形态在调节自由游动的尾虫体内颗粒捕获中的作用；b)确定颗粒形状对尾虫保留效率的影响，并比较合成颗粒和生物颗粒的影响。c)量化颗粒粘附在黏液过滤装置上，以确定微浮游生物细胞的表面特性是否会影响黏液网滤食性生物的滞留效率。