The impact of mixotrophic bacterivory on microbial food webs in changing lake ecosystems (LakeMix)

混合营养菌对不断变化的湖泊生态系统中微生物食物网的影响 (LakeMix)

• 批准号: 329628835
• 负责人: Dr. Mia Bengtsson, Ph.D.
• 金额: --
• 依托单位: Institut für Mikrobiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/329628835?language=en
• 关键词: impact; mixotrophic; bacterivory; microbial; food

Mixotrophic protists, that combine photosynthesis with phagotrophy, are common in marine and freshwater ecosystems. Yet their role in food web dynamics, including trophic interactions, is not well understood. Accumulating evidence from marine environments supports considerable quantitative importance of mixotrophs as bacterivores. Nevertheless, models of the pelagic food web still largely rely on the traditional dichotomy of autotrophic and heterotrophic protists.In lakes, mixotrophic bacterivory has rarely been quantified, and although putatively mixotrophic taxa are numerically abundant there is limited knowledge on how these taxa impact bacterial communities. While it seems obvious that light must play a pivotal role for the potential importance of mixotrophy, experimental evidence on the effect of light on microbial food webs is scarce although light regimes are predicted to change as a result of, for example, altered stratification patterns due to global warming. In LakeMix, we aim to fill these voids by assessing the quantitative and qualitative impact of mixotrophic bacterivory in lakes in the context of climate-related changes.The project is organized around four major tasks: (1) We will perform laboratory experiments with representative heterotrophic and mixotrophic taxa to address competitive interactions and selective feeding, including their impact on bacterial communities under variable light conditions. (2) Mesocosm experiments with natural communities of an oligotrophic lake will serve to test how the relative impact of mixotrophy depends on light intensity in the context of altered lake stratification due to climate change. (3) In a regional lake survey, we will identify the relevant mixotrophic bacterivores along a trophic gradient. (4) A European-scale lake survey that covers large geographical and environmental gradients will be carried out to assess the distribution of prevalent mixotrophic taxa.Our multidisciplinary project combines controlled experimentation in chemostats and mesocosms with comprehensive field observations, thereby spanning several scales of ecological complexity. The unique large-scale mesocosm facility, the IGB LakeLab, will be used in a novel and innovative way to simulate different stratification patterns. State-of-the-art molecular methods and applications, including high-throughput sequencing technology in combination with stable isotope probing and flow cytometry will be used to identify important mixotrophic taxa, and to characterize their impact on bacterial communities. This project will generate crucial quantitative data that is required for incorporating mixotrophy as a key functional trait in microbial food webs and models of lake ecosystems, and shed light on the ecology of this prevalent yet elusive functional group.

混合营养原生生物将光合作用与吞噬作用结合起来，在海洋和淡水生态系统中很常见。然而，它们在食物网动态（包括营养相互作用）中的作用尚不清楚。从海洋环境中积累的证据支持混合营养生物作为食菌动物的相当大的数量重要性。然而，中上层食物网的模型仍然在很大程度上依赖于自养和异养原生生物的传统二分法。在湖泊中，混合营养菌食很少被量化，尽管假定混合营养类群数量丰富，但关于这些类群如何影响细菌群落的知识有限。虽然光显然在混合营养的潜在重要性中发挥着关键作用，但关于光对微生物食物网影响的实验证据却很少，尽管预计光状况会因全球变暖导致的分层模式改变等而发生变化。在 LakeMix 中，我们的目标是通过评估气候相关变化背景下湖泊中混合营养菌的定量和定性影响来填补这些空白。该项目围绕四个主要任务组织：（1）我们将利用代表性的异养和混合营养类群进行实验室实验，以解决竞争性相互作用和选择性进食问题，包括它们在可变光照条件下对细菌群落的影响。 (2) 对寡营养湖泊自然群落进行的中生态实验将有助于测试在气候变化导致湖泊分层改变的背景下，混合营养的相对影响如何取决于光强度。 (3) 在区域湖泊调查中，我们将沿着营养梯度识别相关的混合营养食菌动物。 （4）将进行覆盖大地理和环境梯度的欧洲规模的湖泊调查，以评估普遍的混合营养类群的分布。我们的多学科项目将恒化器和中生态系统的受控实验与全面的现场观察相结合，从而跨越生态复杂性的多个尺度。独特的大型中生态设施 IGB LakeLab 将以新颖且创新的方式来模拟不同的分层模式。最先进的分子方法和应用，包括高通量测序技术与稳定同位素探测和流式细胞术相结合，将用于识别重要的混合营养类群，并表征其对细菌群落的影响。该项目将生成将混合营养作为微生物食物网和湖泊生态系统模型中的关键功能性状所需的关键定量数据，并揭示这一普遍但难以捉摸的功能群的生态学。