Collaborative Research: Diversity and ecological impacts of Antarctic mixotrophic phytoplankton

合作研究：南极混合营养浮游植物的多样性和生态影响

基本信息

批准号：
1744638
负责人：
Wade Jeffrey
金额：
$ 18万
依托单位：
University of West Florida
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2023-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744638&HistoricalAwards=false
关键词：
Collaborative Research Diversity ecological impacts

项目摘要

Traditional models of oceanic food chains have consisted of photosynthetic algae (phytoplankton) being ingested by small animals (zooplankton), which were ingested by larger animals (fish). These traditional models changed as new methods allowed recognition of the importance of bacteria and other non-photosynthetic ?protozoa? in more complex food webs. More recently, the wide-spread existence of mixotrophs (organisms that can both photosynthesize and ingest food particles) and their importance as microbial predators has been recognized in many oceanographic areas. In the Southern Ocean, the only two surveys of mixotrophs have suggested that there may be seasonal differences in their importance as predators. During the long polar night (winter), the ability of mixotrophs to ingest particulate food may aid in their survival thus ensuring a sufficient population in spring to support a phytoplankton bloom once photosynthesis rates can increase. Thus mixotrophs may provide a critical early food source upon which zooplankton and larger animals depend on for growth and reproduction. This project will advance understanding of mixotroph diversity and their ecological impact within the Southern Ocean microbial food web. Specifically, efforts will be focused on mixotrophy in the western Antarctica peninsula region during the austral spring and autumn when there are likely to be changes in the relative importance of photosynthesis and ingestion to mixotrophs. The project will provide research opportunities for undergraduate and graduate students and a post-doctoral researcher. There will be real-time outreach from the Southern Ocean to the public via blogs and interviews, and to high school art students through an established program that blends science and art education. Despite traditional views of protists as either "phototrophic" or "heterotrophic," there are many photosynthetic protists that consume prey (mixotrophy). Mixotrophy is a widespread phenomenon in aquatic systems and phytoplankton groups with known mixotrophic species, notably chrysophytes, cryptophytes, prymnesiophytes, prasinophytes and dinoflagellates, are present and often abundant in Antarctic waters. However, in the Southern Ocean, the presence of mixotrophic phytoflagellates has been surveyed only twice: in the Ross Sea during Austral spring 2008 and summer 2011. The primary goals of the project are to gain better understanding of mixotroph diversity and their ecological impact with respect to the Southern Ocean microbial food web. The contribution of mixotrophs to primary production and bacterial consumption is likely linked to the taxonomic composition of the community and the abundance of particular species. Abundances of novel mixotrophic species will be evaluated via qPCR, which will be coupled with assessments of rates of feeding and photosynthesis with the goal of describing how active mixotrophs direct the movement of carbon through food webs. These experiments will help the determination of how viable and widespread mixotrophy is as a nutritional strategy in polar waters and give direct information on the currently unknown diversity of mixotrophic taxa under different environmental conditions occurring in austral spring and autumn. Furthermore, the methods will simultaneously yield information on the whole communities of protists - mixotrophic, phototrophic and heterotrophic. In addition, a method to examine aspects of the taxonomic and functional diversities of the bacterivorous/mixotrophic community will be employed. A thymidine analog (BrdU) will be used to label DNA of eukaryotes feeding on bacteria. The BrdU-labeled eukaryotic DNA will be isolated using immunoprecipitation. High-throughput sequencing of the labeled DNA (bacterivores) versus unlabeled community DNA will determine the diversity of bacterivorous mixotrophs relative to other microeukaryotes. Flow cytometric sorting based on chlorophyll to focus on mixotrophic species. These approaches will elucidate a gap in current knowledge of the influence of microbial interactions in the Southern Ocean under different conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海洋食物链的传统模型由小动物（浮游动物）摄入的光合藻类（浮游植物）组成，而大型动物（鱼类）又摄入小动物（浮游动物）。随着新方法允许人们认识到细菌和其他非光合作用“原生动物”的重要性，这些传统模型发生了变化。在更复杂的食物网中。最近，混合营养生物（既能进行光合作用又能摄取食物颗粒的生物）的广泛存在及其作为微生物捕食者的重要性已在许多海洋学领域得到认识。在南大洋，仅有的两次混合营养生物调查表明，它们作为捕食者的重要性可能存在季节性差异。在漫长的极夜（冬季），混合营养生物摄入颗粒食物的能力可能有助于它们的生存，从而确保春季有足够的种群来支持光合作用速率增加时浮游植物的繁殖。因此，混合营养生物可能提供浮游动物和大型动物赖以生长和繁殖的关键早期食物来源。该项目将增进对南大洋微生物食物网中混合营养生物多样性及其生态影响的了解。具体来说，工作重点将集中在南极洲西部半岛地区春季和秋季期间的混合营养，此时光合作用和摄入对混合营养生物的相对重要性可能会发生变化。该项目将为本科生、研究生以及博士后研究员提供研究机会。南大洋将通过博客和采访向公众进行实时宣传，并通过融合科学和艺术教育的既定计划向高中艺术学生进行实时宣传。尽管传统观点认为原生生物要么是“光养的”，要么是“异养的”，但仍有许多光合作用的原生生物会消耗猎物（混合营养）。混合营养是水生系统和浮游植物群体中的一种普遍现象，已知的混合营养物种，特别是金藻类、隐藻类、裸藻类、绿藻类和甲藻类，在南极水域中存在且经常丰富。然而，在南大洋，混合营养型植物鞭毛藻的存在仅进行了两次调查：2008 年春季和 2011 年夏季在罗斯海。该项目的主要目标是更好地了解混合营养型多样性及其生态影响南大洋微生物食物网。混合营养生物对初级生产和细菌消耗的贡献可能与群落的分类组成和特定物种的丰富度有关。新型混合营养物种的丰度将通过 qPCR 进行评估，这将与摄食和光合作用速率的评估相结合，目的是描述活跃的混合营养物种如何引导碳通过食物网的移动。这些实验将有助于确定混合营养作为极地水域营养策略的可行性和广泛性，并提供有关在南方春季和秋季发生的不同环境条件下目前未知的混合营养类群多样性的直接信息。此外，这些方法将同时产生整个原生生物群落的信息——混合营养、光养和异养。此外，还将采用一种方法来检查食菌/混合营养群落的分类和功能多样性。胸苷类似物 (BrdU) 将用于标记以细菌为食的真核生物的 DNA。使用免疫沉淀法分离 BrdU 标记的真核 DNA。标记 DNA（食菌动物）与未标记群落 DNA 的高通量测序将确定食菌混合营养生物相对于其他微真核生物的多样性。基于叶绿素的流式细胞术分选，重点关注混合营养物种。这些方法将阐明目前对不同条件下南大洋微生物相互作用的影响的认识上的差距。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。