Collaborative Research: Trophic ecology of small hydromedusae: a new perspective on their function in coastal ecosystems

合作研究：小型水螅的营养生态学：其在沿海生态系统中功能的新视角

• 批准号: 0350970
• 负责人: Dian Gifford
• 金额: $ 48.03万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0350970&HistoricalAwards=false
• 关键词: Collaborative; Research; Trophic; ecology; small

The focus of the research is the trophic role of small (bell diameter 5 mm) hydromedusae. Medusae are important, often highly selective, planktonic predators that can strongly affect standing stocks of metazoan zooplankton as well as fish eggs and larvae. The feeding rates, prey selection patterns and the underlying feeding mechanisms that have led to the success of large, conspicuous medusae have been well studied. However, most medusae are small. These small medusae are abundant, taxonomically diverse, and often have cosmopolitan distributions. Yet their feeding ecology is virtually unknown despite their status as the largest and most diverse group of gelatinous zooplankton in the sea. Preliminary data indicate that many small hydromedusae feed differently and have different trophic roles than their larger relatives. These preliminary studies have shown that some small medusan species (1) feed as omnivores on microplankton, including phytoplankton and (2) are sufficiently abundant and have sufficiently high feeding rates to remove a significant proportion of the phytoplankton standing stock in the coastal ecosystems where they occur seasonally. This project will address the hypothesis that this combination of high abundance and high feeding rates enables small hydromedusae to function as significant grazers of phytoplankton during periods of peak seasonal production. Consequently, the contemporary paradigm that medusae are primarily predators of planktonic metazoans may require significant revision in order to encompass the trophic role of small hydromedusae. The goal of the research is to examine the feeding processes and impact of small hydromedusae by examining their trophic role in Narragansett Bay, Rhode Island. We will use a combined approach of (1) quantifying the trophic impact of small hydromedusae on the plankton community of Narragansett Bay, Rhode Island and (2) quantifying the functional bases of their feeding and prey selection. Intellectual Merit of the Proposed Activity: The research will lead to new understanding of community feeding rates, prey selection patterns and the underlying feeding mechanisms that have led to the success and evolutionary longevity of the most diverse taxonomic group of medusae. If small medusae feed primarily as omnivores on microplankton and are able to significantly affect microplankton standing stocks, then the research will document a new and important trophic link between the metazoan and microbial food webs. The new knowledge will provide protistan ecologists with enhanced understanding of the factors controlling microplankton standing stocks and production rates. The study will also provide evolutionary ecologists with a greater understanding of the biomechanical factors that have influenced the evolution of small hydromedusan body form and function as well as protist behavior and body form. From this perspective, this study directly addresses the issue of understanding factors influencing biological diversity and its ecological consequences in marine systems, a specific theme emphasized by NSF's Biological Oceanography division. Broader impacts of the Proposed Activity: The project will encourage scientific discovery by documenting a new, but presumably common, trophic link in pelagic food webs. The participation of scientists from two primarily undergraduate institutions and one primarily graduate institution enhances opportunities for training and mentorship. Each institution will involve students in every aspect of the research (5 undergraduates during each year of the proposal, 2 from RWU and 2 from PC; 1 undergraduate from the Marine Biology program at URI will do an independent study course (15 credits) with Gifford during the spring academic term of each project year). Upon receipt of funding, Gifford will apply for a budget supplement to support participation in the project by a secondary school science teacher during the summer months. As in the past, we will use our contacts with media involved in education of the general public (radio, television documentaries, news articles and aquarium exhibits) to communicate our new findings about medusan ecology. Our continuing dialog with these outlets to the public allows us avenues to communicate our findings to a wide public audience and to educate the general public.

研究的重点是小水螅水母（钟直径5毫米）的营养作用。水母是重要的，往往是高度选择性的，浮游动物的捕食者，可以强烈影响后生浮游动物以及鱼卵和仔鱼的常备库存。摄食率，猎物选择模式和潜在的摄食机制，导致了大型，引人注目的水母的成功已经得到了很好的研究。然而，大多数水母都很小。这些小水母是丰富的，分类多样，往往有世界性的分布。然而，尽管它们是海洋中最大和最多样化的凝胶状浮游动物群体，但它们的摄食生态实际上是未知的。初步数据表明，许多小水螅水母的饲料不同，并有不同的营养作用比他们的大亲戚。这些初步研究表明，一些小水母物种（1）以包括浮游植物在内的微型浮游生物为杂食性动物，（2）数量充足，摄食率高，足以消除它们季节性出现的沿海生态系统中相当大一部分浮游植物现存量。该项目将解决这样一个假设，即高丰度和高摄食率的结合使小型水螅水母能够在季节性生产高峰期作为浮游植物的重要食草动物发挥作用。因此，当代的范式，水母主要是食肉动物的水生后生动物可能需要重大修订，以包括小水螅水母的营养作用。这项研究的目的是通过研究小型水螅水母在罗得岛纳拉甘塞特湾的营养作用来研究它们的进食过程和影响。我们将使用一个综合的方法（1）量化的营养影响的小型水螅水母的浮游生物群落的纳拉甘塞特湾，罗得岛和（2）量化的功能基础，其喂养和猎物的选择。拟议活动的知识价值：该研究将导致对群落摄食率、猎物选择模式和潜在摄食机制的新理解，这些摄食机制导致了最多样化的水母分类群的成功和进化寿命。如果小水母主要以微型浮游生物为杂食动物，并能够显著影响微型浮游生物的现存量，那么这项研究将记录后生动物和微生物食物网之间新的重要营养联系。新的知识将使原生生物生态学家更好地了解控制微型浮游生物现存量和生产率的因素。这项研究还将使进化生态学家更好地了解影响小型水螅水母体型和功能以及原生生物行为和体型进化的生物力学因素。从这个角度来看，本研究直接解决了理解影响生物多样性的因素及其在海洋系统中的生态后果的问题，NSF的生物海洋学部门强调的一个特定主题。拟议活动的更广泛影响：该项目将通过记录一种新的、但可能是常见的浮游食物网营养链，鼓励科学发现。来自两个主要是本科生的机构和一个主要是研究生的机构的科学家的参与增加了培训和指导的机会。 每个机构将涉及学生在研究的各个方面（5个本科生在每年的提案，2从RWU和2从PC; 1个本科生从海洋生物学程序在URI将做一个独立的学习课程（15学分）与吉福德在每个项目年的春季学期）。在收到资金后，吉福德将申请预算补充，以支持在夏季几个月的中学科学教师参与该项目。与过去一样，我们将利用与参与公众教育的媒体（广播、电视纪录片、新闻文章和水族馆展览）的联系，传播我们对水母生态的新发现。 我们与这些媒体的持续对话使我们能够向广大公众传达我们的调查结果并教育公众。