Collaborative Research: Algal photosynthetic priming and photolysis as stimulators of ecosystem-level detrital processing by microbial heterotrophs

合作研究：藻类光合启动和光解作用作为微生物异养生物生态系统级碎屑处理的刺激剂

• 批准号: 1457217
• 负责人: Kevin Kuehn
• 金额: $ 52.14万
• 依托单位: University of Southern Mississippi
• 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: 2015-10-01 至 2019-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1457217&HistoricalAwards=false
• 关键词: Collaborative; Research; Algal; photosynthetic; priming

Freshwater wetlands provide many valuable ecosystem services, including the provision of food and habitat for wildlife, improvement of water quality, flood protection, and defense of lake shorelines from erosion. These attributes make wetlands a significant environmental, recreational, and economic resource for our nation. In freshwater wetlands, tall plants emerging from the water, such as cattails, often account for a large fraction of the plant matter produced. These plants exhibit prolific rates of growth and absorb large amounts of nutrient contaminants, improving water quality in the process. Most of this plant matter is not directly consumed by animals, but instead dies and is decomposed by microorganisms (bacteria and fungi). During decomposition, nutrients trapped within plant tissues may be released via the activity of bacterial and fungal decomposers. Bacteria and fungi growing on decaying plants also serve as a key food resource for many invertebrate animals, and form a link in the flow of energy and nutrients up the food chain (to fish and waterfowl, for example) in wetland habitats. As a consequence, the productivity, nutrient uptake, and decomposition of emergent plants will profoundly affect nearly all aspects of wetland function. This research project will measure the importance of bacteria and fungi in wetland plant decay, and investigate how their potential interactions with algae affect rates of plant matter decomposition and nutrient cycling. Microorganisms are key players in the circulation of nutrients on Earth. This circulation, often referred to as biogeochemical cycling, includes all of the biological, geological and chemical factors that are involved. Understanding the ecology of microorganisms is essential for us to meet the major challenges facing human society, such as conservation and management of natural ecosystems and mitigation of climate change. In addition to training a postdoctoral scholar, this research will train undergraduate and graduate students through a collaborative, multifaceted effort to understand a key ecosystem process, decomposition. Through these efforts researchers will also participate in a series of existing university programs and coordinated outreach activities aimed at recruiting underrepresented groups into the sciences and strengthening science education at the elementary through university levels.The overarching goal of this project is to understand the nature of metabolic interactions among algae, bacteria, and fungi in decomposing plant litter, and to quantify how these interactions influence plant litter decomposition and carbon cycling in wetlands. Photolysis of dissolved and particulate organic matter is widely accepted as an important abiotic decomposition process in aquatic ecosystems. In contrast, enhanced decomposition via algal stimulation of litter-associated heterotrophic microbes has only recently been considered. Prior research by this team has documented rapid metabolic responses of heterotrophic microbes to algal photosynthesis in natural decaying plant litter, thus establishing the potential for algal "priming effects" on microbial-mediated litter decomposition, yet, the relative importance of algal priming and photolysis in facilitating litter decomposition in aquatic ecosystems remains unknown. This project will involve a series of field and laboratory experiments in marsh ecosystems, investigating three key questions centered on photostimulation of litter decomposition: 1) What is the relative importance of algal photosynthetic priming vs. photolysis in facilitating microbial-mediated organic matter decomposition? 2) What is the influence of photolysis and autotroph-heterotroph interactions on ecosystem-scale carbon cycling" 3) What are the mechanisms mediating autotroph-heterotroph interactions in decaying plant litter?

淡水湿地提供了许多宝贵的生态系统服务，包括为野生动物提供食物和栖息地，改善水质，防洪和保护湖岸线免受侵蚀。这些属性使湿地成为我们国家重要的环境，娱乐和经济资源。在淡水湿地中，从水中出现的高大植物，如香蒲，通常占植物物质产生的很大一部分。这些植物表现出多产的生长速度，并吸收大量的营养污染物，在此过程中改善水质。这些植物物质中的大部分并不直接被动物消耗，而是死亡并被微生物（细菌和真菌）分解。在分解过程中，植物组织中捕获的营养物质可以通过细菌和真菌分解剂的活动释放出来。生长在腐烂植物上的细菌和真菌也是许多无脊椎动物的主要食物来源，并在湿地栖息地的食物链（例如鱼类和水禽）中形成能量和营养流动的联系。因此，生产力，营养吸收，和挺水植物的分解将深刻地影响湿地功能的几乎所有方面。该研究项目将测量细菌和真菌在湿地植物腐烂中的重要性，并研究它们与藻类的潜在相互作用如何影响植物物质分解和养分循环的速率。微生物是地球上营养循环的关键角色。这种循环，通常被称为地球化学循环，包括所涉及的所有生物，地质和化学因素。了解微生物生态学对于我们应对人类社会面临的重大挑战至关重要，例如保护和管理自然生态系统以及减缓气候变化。除了培养博士后学者外，这项研究还将通过协作，多方面的努力来培养本科生和研究生，以了解关键的生态系统过程，分解。通过这些努力，研究人员还将参与一系列现有的大学项目和协调的外展活动，旨在招募代表性不足的群体进入科学领域，并加强小学到大学的科学教育。该项目的总体目标是了解藻类，细菌和真菌在分解植物垃圾时代谢相互作用的性质，并量化这些相互作用如何影响湿地中植物凋落物分解和碳循环。 溶解态和颗粒态有机物的光解是水生态系统中重要的非生物降解过程。相比之下，通过藻类刺激的垃圾相关的异养微生物的增强分解最近才被考虑。该团队先前的研究记录了异养微生物对自然腐烂植物凋落物中藻类光合作用的快速代谢反应，从而建立了藻类对微生物介导的凋落物分解的潜在“引发效应”，然而，藻类引发和光解在促进水生生态系统中凋落物分解的相对重要性仍然未知。该项目将涉及一系列的现场和实验室实验在沼泽生态系统中，调查三个关键问题集中在凋落物分解的光刺激：1）什么是藻类光合启动与光解在促进微生物介导的有机物分解的相对重要性？2)光解和自养-异养相互作用对生态系统尺度碳循环的影响是什么？3）在腐烂的植物凋落物中调节自养-异养相互作用的机制是什么？