Collaborative Research: Cascading effects of an invasive seaweed on estuarine food webs of the southeastern US

合作研究：入侵海藻对美国东南部河口食物网的连锁效应

• 批准号: 1057713
• 负责人: Erik Sotka
• 金额: $ 26.54万
• 依托单位: College of Charleston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1057713&HistoricalAwards=false
• 关键词: Collaborative; Research; Cascading; effects; invasive

During the last decade, the Asian seaweed, Gracilaria vermiculophylla, has proliferated along high-salinity mudflats in several Georgia and South Carolina estuaries. The invasion is noteworthy because the mudflats in these estuaries were historically devoid of macrophyte-based primary production and structure. Gracilaria has few native analogues in these mudflat environments, and thus represents an opportunity to examine the ecosystem consequences of an invasion within an historically-unexploited niche. In theory, Gracilaria affects populations of species that are directly dependent on the invader for structure and food, as well as altering community- and ecosystem-level processes such as detrital production and food web structure. Through a combination of manipulative field experiments, laboratory assays and stable isotope analysis, the investigators will test three mechanisms by which Gracilaria influences native community structure. The novel structure and primary production generated by Gracilaria vermiculophylla may be 1) increasing rates of secondary production 2) increasing levels of mudflat microbial production through leeching of dissolved nutrients, and 3) increasing detrital input to microbial and macrobial food webs. This project will provide a mechanistic understanding of the multiple cascading impacts of an invasive species within the estuarine community. Species invasions that alter ecosystem functions are usually the most profound. These alterations are often generated by a small number of invaders that create physical structure, including important biogenic habitat, de novo. By altering physical structure, these non-native ecosystem engineers alter local abiotic conditions, interactions between species, and species composition. Highly influential invaders may also change food web structure and trophic flow of energy and materials. Such substantive food web changes can occur when an influential invader provides nutrients or resources that are different in quality, quantity or both. An invasive species that both provisions new physical structure and fundamentally alters food web structure could exert an overwhelming influence on native communities when these mechanisms act in synergy.The project also includes education and outreach components, especially mentoring. It will prepare two graduate and three undergraduate students for scientific careers by having them independently develop projects related to the project. Their research will integrate the traditional experimental techniques used to study invasive species with advanced analytic techniques of stable isotope analyses, PCR-based identification of gut contents, and enumeration of microbial communities. Consistent with their past projects and the goals of NSF, the PIs are committed to mentoring a diverse group of students across multiple educational levels (high school, undergraduate, graduate) and ethnicities. They will involve two high school science teachers through a "teacher as researcher" program to participate in field and laboratory projects. Each will conduct research and be expected to develop new unit plans for their classrooms. Finally, the PIs will continue to disseminate their results to the public through lectures, open house events at their institutions, as well as radio, newspaper, and television interviews. Finally, this study will be of immediate benefit to managers charged with mitigating the impacts of invasive species.

在过去的十年中，亚洲海藻江蓠在佐治亚州和南卡罗来纳州几个河口的高盐度泥滩上大量繁殖。这次入侵值得注意，因为这些河口的泥滩历史上缺乏以大型植物为基础的初级生产和结构。在这些泥滩环境中，江蓠几乎没有本地类似物，因此提供了一个机会来研究历史上未开发的生态位中入侵的生态系统后果。理论上，江蓠会影响直接依赖入侵者获取结构和食物的物种种群，并改变群落和生态系统层面的过程，例如碎屑生产和食物网结构。通过结合现场操作实验、实验室分析和稳定同位素分析，研究人员将测试江蓠影响本地群落结构的三种机制。龙须草产生的新颖结构和初级生产力可能是：1）提高次级生产力2）通过溶解营养物质的浸出提高滩涂微生物生产水平，3）增加微生物和微生物食物网的碎屑输入。该项目将对河口群落内入侵物种的多重级联影响提供机械理解。改变生态系统功能的物种入侵通常影响最为深远。这些改变通常是由少数入侵者产生的，这些入侵者从头创造了物理结构，包括重要的生物栖息地。通过改变物理结构，这些非本地生态系统工程师改变了当地的非生物条件、物种之间的相互作用和物种组成。具有高度影响力的入侵者还可能改变食物网结构以及能量和物质的营养流动。当有影响力的入侵者提供质量、数量或两者都不同的营养或资源时，就会发生这种实质性的食物网变化。当这些机制协同作用时，既提供新的物理结构又从根本上改变食物网结构的入侵物种可能对当地社区产生压倒性的影响。该项目还包括教育和外展部分，特别是指导。它将通过让两名研究生和三名本科生独立开发与该项目相关的项目，为他们的科学职业做好准备。他们的研究将把用于研究入侵物种的传统实验技术与稳定同位素分析、基于 PCR 的肠道内容物鉴定和微生物群落计数等先进分析技术相结合。与他们过去的项目和 NSF 的目标一致，PI 致力于指导跨多个教育级别（高中、本科、研究生）和种族的多元化学生群体。他们将通过“教师即研究员”计划让两名高中科学教师参与现场和实验室项目。每个人都将进行研究，并预计为他们的教室制定新的单元计划。最后，PI 将继续通过讲座、所在机构的开放日活动以及广播、报纸和电视采访向公众传播他们的研究结果。最后，这项研究将为负责减轻入侵物种影响的管理者带来直接好处。