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）或仅通过摄取/同化有机物质（异养）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，联合收割机在一个单一的有机体中结合光养和异养，是营养食物网的重要组成部分。 根据先前的工作，研究人员已经证实了混合营养体在北极和南极沃茨中无处不在的性质，并假设北极表面沃茨变暖的一个可能后果是，微微和纳米混合营养体将在该地区变得更加丰富。 研究人员将使用来自北极各地的水样进行实验室实验，以更好地了解触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如何在气候变暖中发挥作用的信息，以及这些变化将如何潜在地影响鱼类等更高的营养水平。这项工作将提供一个可能的转型重新定位我们目前的看法地表水食物网的结构和动态和营养流在不断变化的北极。 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外联，并与马萨诸塞州法尔茅斯的一所学校进行合作。作为新艺术科学项目（STEAM）的一部分，研究人员预测，随着北极水温变暖，海洋食物网将受到双重影响。 首先，他们预测微微和纳米浮游植物对初级生产的贡献会增加。 其次，他们预测，由于许多微微和纳米浮游植物物种表现出混合营养行为的事实，细菌消费的影响。 研究人员提出了一些实验室实验的藻类群体菌株已被确定为兼养物种，并发现在北极沃茨。 北极海洋分离物将从罗斯科夫培养物保藏中心和国家海洋藻类中心获得。 物种特定的兼养活动和放牧率将在一系列触发和/或刺激兼养的环境条件下确定，如高/低光照和高/低营养。 根据这些特定物种的测量结果，沿着qPCR分析以确定整个北极海洋环境水样中的物种丰度，可以在整个北极评估混合营养活动的潜在影响。 最后，为了确定和比较环境样品中的混合营养活性水平，而不依赖于摄入实验，研究人员将开发基于RNA测序和上述环境响应实验结果的基于基因的活性方法。 这对于预测一个更温暖的世界将是重要的。

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.