Collaborative Research: The Ecological Impact of Mixotrophic Algae in a Changing Arctic Marine Climate

大多数生物仅通过光合作用(光养作用)或有机物质的摄取/同化(异养作用)来满足其碳和能量需求。然而，越来越多的人认识到，混合营养生物是浮游食物网的重要组成部分，它们在单个有机体中结合了光养和异养。根据先前的工作，研究人员确认了北极和南极水域中混合营养生物普遍存在的性质，并假设北极表层水域变暖的一个可能后果是该地区的微米和纳米混合营养生物将变得更加丰富。研究人员将利用北极各地的水样进行实验室实验，以更好地了解引发混合营养活动的环境条件。这些实验还将提供有关微生物食物网在气候变暖中如何发挥作用以及这种变化将如何潜在地影响更高营养水平的信息，如鱼类。这项工作可能会对我们目前对地表水、食物网、结构和动态以及变化中的北极营养物质流动的看法进行变革性的重新定位。该项目将培养一名博士后科学家、研究生和本科生。此外，该项目还包括与费城市区的当地学校进行接触，以及与马萨诸塞州法尔茅斯的合作。作为新的艺术科学项目(STEAM)的一部分的高中艺术老师。随着北极水温变暖，研究人员预测对海洋食物网的双重影响。首先，他们预测微藻和纳米浮游植物对初级生产力的贡献将会增加。其次，他们预测了对细菌消耗的影响，因为许多微微和纳米浮游植物物种表现出混合营养行为。研究人员提议对已被确认为混合营养物种的藻类群菌株进行一些实验室实验，这些藻类群在北极水域发现。北极海洋分离株将从Roscoff培养库和国家海洋藻类中心获得。物种特定的混合营养活动和放牧率将在触发和/或刺激混合营养的一系列环境条件下确定，例如高/低光照和高/低营养。从这些特定物种的测量，以及确定整个北极海洋环境水样中物种丰度的定量聚合酶链式反应分析，可以在整个北极的基础上评估混合营养活动的潜在影响。最后，为了在不依赖摄取实验的情况下确定和比较环境样品中混合营养活性的水平，研究人员将开发一种基于基因的活性方法，该方法基于RNA测序和上述环境响应实验的结果。这对于在全球变暖的情况下进行预测将是很重要的。

Most organisms meet their carbon and energy needs solely on photosynthesis (phototrophy) or solely on ingestion/assimilation of organic substances (heterotrophy). However, there is increasing recognition that mixotrophs, which combine phototrophy and heterotrophy in a single organism, are important components of planktonic food webs. Based on prior work, the investigators have confirmed the ubiquitous nature of mixotrophs in Arctic and Antarctic waters and hypothesize that a possible consequence to the warming of Arctic surface waters is that pico- and nano-mixotrophs will become more abundant in the region. Using water samples from across the Arctic, the investigators will conduct laboratory experiments to better understand the environmental conditions that trigger mixotrophic activity. Such experiments will also provide information on how the microbial food web will function in a warming climate and how such changes will potentially affect higher trophic levels, such as fish. This work will provide a possibly transformative re-orienting of our current view of surface water food webs structure and dynamics and nutrient flows in a changing Arctic. The project will train a post doctoral scientist, graduate, and undergraduate student. In addition, the project includes outreach to local schools in urban Philadelphia, and collaboration with a Falmouth, MA. high school art teacher as part of novel art-science projects (STEAM).As Arctic water temperatures warm, the investigators predict a two-fold effect on the marine food web. First, they predict an increased contribution to primary production from pico- and nano-phytoplankton. Second, they predict an impact on bacterial consumption owing to the fact that many of the pico- and nano-phytoplankton species exhibit mixotrophic behavior. The investigators propose a number of laboratory experiments on strains of algal groups that have been identified as mixotrophic species and are found in Arctic waters. Arctic marine isolates will be acquired from the Roscoff Culture Collection and the National Center of Marine Algae. Species specific mixotrophic activity and grazing rates will be determined across a range of environmental conditions that trigger and/or stimulate mixotrophy, such as high/low light and high/low nutrients. From these species specific measurements, along with qPCR analysis to determine species abundances in water samples from across the Arctic marine environment, the potential impact of mixotrophic activity can be assessed on an Arctic-wide basis. Finally, to determine and compare the levels of mixotrophic activity in environmental samples without relying on ingestion experiments the investigators will develop a gene-based method of activity based upon RNA sequencing and the results of the environmental response experiments discussed above. This will be important for prediction in a warmer world.