Collaborative Research: Trophodynamics of Myrionecta rubra and cryptophyte algae

红多棘虫（Myrionecta rubra）是中缢虫科（Mesodiniumrubrum）中缢虫科（Mesodinidae）中缢虫属（Mesodiniumrubrum）的一种无毒的赤潮纤毛虫，分布于世界各地的沿海和河口沃茨。M. Rubra具有来自隐藻的共生细胞器，隐藻是水生生态系统中普遍存在的藻类。由于纤毛虫通常被认为是原生动物，单细胞真核生物具有动物而不是植物的性质，M。红宝石一直被认为是一个谜。浮游植物生态学的研究常常忽略了M。rubra，而不是考虑它的微型浮游动物的一部分。在过去的十年里，在了解纤毛虫的功能方面取得了很大的进展，这主要归功于文化的建立。最近的研究表明，一株M. Rubra从隐藻的猎物中窃取细胞器（叶绿体、线粒体和细胞核），而另一种则拥有稳定（永久）的隐藻细胞器。然而，所有的纤毛虫都必须以隐藻为食，以获得细胞器或生长因子。虽然我们现在对M.红，几乎没有什么是已知的关于其生态相互作用与隐藻藻类，细菌，和潜在的捕食者在水生生态系统。隐藻是切萨皮克湾的主要浮游植物类群之一，对初级生产有贡献，并作为各种生物的主要食物。M.红珊瑚在切萨皮克湾及其支流分布广泛，季节性丰富，在春季和秋季可达到赤潮浓度。目前对隐藻和M.本研究的目的是确定调节红球藻生产的物理和化学因素以及生物相互作用。红和隐藻，并描述这些生物的遗传多样性的范围和季节模式在切萨皮克湾。另一个目标是确定隐藻遗传多样性在产生多囊藻纤毛虫中的作用。利用海洋学，生理学和分子方法，研究小组建议对这种独特且具有生态重要性的纤毛虫进行首次大规模生态研究，以了解其在海洋微生物食物网中的作用，并更好地预测其丰度和分布。该项目的重要性有两个原因，1）M。红藻是几乎所有海岸生态系统中浮游生物的主要成员，但其营养作用仍然是一个谜; 2）隐藻藻类在大多数河口和海岸生态系统中起着关键作用，但它们仍然是一个缺乏特征的鞭毛虫“黑匣子”。尽管有许多关于M.虽然我们对赤潮的生态系统仍有初步的了解，但我们对赤潮的兼养作用，如浮游生物和食草动物，以及这些策略如何在自然食物网中平衡，仍有初步的了解。M.与切萨皮克湾和其他沿海生态系统中的许多其他混养生物一样，红球藻与隐藻藻类生产有关。然而，我们目前无法预测的生态系统动态的M。Rubra，很大程度上是由于我们缺乏对隐花植物猎物选择、隐花植物生产的时空动态以及放牧压力对水华形成和终止的影响的了解。切萨皮克湾是进行这项研究的理想地点。红珊瑚和隐藻极为丰富，它们的生产力在时间和地点上是季节性可预测的，取样地点也很容易到达，这项活动将通过教育公众了解微生物多样性和微生物食物网的相互作用来促进海洋科学素养。该项目的成果将通过科学论文、讲习班介绍、会议、研讨会、对现有和新网站的贡献以及与媒体的讨论等方式广泛传播。本科生将通过WHOI冬季和夏季研究计划参与该项目。这一建议也将有助于青年科学家的专业发展。

Myrionecta rubra (Mesodinium rubrum; Family Mesodiniidae) is a non-toxic red-tide forming ciliate in coastal and estuarine waters of the world. M. rubra possesses symbiotic organelles derived from cryptophyte algae, a ubiquitous group of algae in aquatic ecosystems. Because ciliates are usually considered protozoa, unicellular eukaryotes that have animal rather than plant-like qualities, M. rubra was long considered an enigma. Studies of phytoplankton ecology have frequently overlooked M. rubra, instead considering it part of the microzooplankton. In the last decade great progress has been made in understanding how the ciliate functions, largely due to the establishment of cultures. Recent studies have shown that one strain of M. rubra steal organelles (chloroplasts, mitochondria, and a nucleus) from cryptophyte prey, while another possesses stable (permanent) cryptophyte organelles. All strains of the ciliate, however, must feed on cryptophyte algae, either for acquiring organelles or growth factors. While we now have a greater understanding of the physiology of M. rubra, almost nothing is known regarding its ecological interactions with cryptophyte algae, bacteria, and potential predators in aquatic ecosystems. Cryptophyte algae are one of the major phytoplankton groups in Chesapeake Bay, contributing to primary production and acting as a major food item for a variety of organisms. M. rubra is widespread and seasonally abundant in Chesapeake Bay and its tributaries, and can reach red-tide concentrations in the spring and fall. Little is known regarding the genetic diversity of cryptophyte or M. rubra populations in Chesapeake Bay or other ecosystems.The objectives of this study are to determine the physical and chemical factors and biological interactions that regulate production of M. rubra and cryptophytes, and to characterize the range and seasonal patterns of genetic diversity of these organisms in Chesapeake Bay. Another goal is to determine the role of cryptophyte genetic diversity in the production of Myrionecta ciliates. Using oceanographic, physiological, and molecular approaches, the team of investigators proposes to execute the first large scale ecological studies of this unique and ecologically important ciliate, in order to understand its role in marine microbial food webs and to better predict its abundance and distribution. The Project is important for two reasons, 1) M. rubra can be a dominant member of the plankton in nearly all coastal ecosystems, yet its trophic role remains enigmatic and 2) cryptophyte algae play a pivotal role in the ecology of most estuarine and coastal ecosystems, yet they remain a "black box" of poorly characterized flagellates. Despite numerous reports of M. rubra red tides, we still have a rudimentary understanding of its mixotrophic role, as both alga and grazer, and how these strategies are balanced in natural food webs. The production of M. rubra, like many other mixotrophs in Chesapeake Bay and other coastal ecosystems, is linked to cryptophyte algal production. However, we are currently unable to predict ecosystem dynamics of M. rubra, due largely to our lack of knowledge of their cryptophyte prey selection, the spatial and temporal dynamics of cryptophyte production, and the effects of grazing pressure on bloom formation and termination. The Chesapeake Bay is an ideal location to perform this research because both M. rubra and cryptophytes are extremely abundant, their productivity is seasonally predictable in its timing and location, and sampling sites are easily accessible.This activity will be used to advance Ocean Science Literacy by educating the public about microbial diversity and microbial food web interactions. Results from this project will be broadly disseminated through scientific papers, workshop presentations, conferences, seminars, contributions to existing and new web sites, and discussions with the media. Undergraduates will participate in this project through the WHOI winter and summer research program. This proposal will also contribute to the professional development a young scientist.