Light-aided digestion of Phytoplankton Prey by Heterotrophic Protist Grazers

异养原生食草动物对浮游植物猎物的光辅助消化

• 批准号: 0002479
• 负责人: Suzanne Strom
• 金额: $ 43.71万
• 依托单位: Western Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-15 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0002479&HistoricalAwards=false
• 关键词: Light; aided; digestion; Phytoplankton; Prey

Light, in conjunction with nutrient supply, is the primary abiotic resource structuring life in the sea. With the exception of various behavioral phenomena such as phototaxis and bioluminescence, light has not been thought to directly influence marine zooplankton energetics. In recent research, we have found evidence for the direct use of light energy in the digestion of phytoplankton by three heterotrophic (non?photosynthetic) protists. We hypothesize that light aids in the digestion of phytoplankton prey through the photosensitized formation of reactive oxygen in grazer food vacuoles. This reactive oxygen may then degrade lipids and proteins, supplementing digestion both qualitatively (by yielding smaller, more readily assimilated compounds) and quantitatively (by providing an energy supplement). Our data indicate that light?aided digestion can result in 2? to 10- fold enhancements of ingestion rate, and up to 20?fold enhancements of population growth rates. At very low food levels, light?aided digestion can make the difference between survival and severe mortality for heterotrophic protists feeding on phytoplankton.Because protists are the primary consumers of phytoplankton in the sea, light?aided digestion has profound consequences for the regulation of phytoplankton consumption, nutrient regeneration, trophic transfer efficiency, and prey selection. We propose an investigation of the role of light in regulating protist grazing activities. The proposed research will be conducted across multiple biological levels, from molecular events in grazer food vacuoles to regulation of phytoplankton consumption in whole microplankton communities. The proposed research centers on the exciting notion that light, a fundamental abiotic resource, may regulate the activities of the ocean's primary herbivores on the fundamental level of prey digestion. A direct coupling of protist grazing, growth, and growth efficiency to irradiance means that these rates and efficiencies will vary with depth, latitude, and season in a heretofore-unsuspected manner. In addition, the degree of coupling between populations of phytoplankton and their primary consumers, a fundamental determinant of community structure and function, could be strongly mediated by a single abiotic resource, and thus might be much closer than previously believed.

光与营养供应一起是构成海洋生命的主要非生物资源。除了趋光性和生物发光等各种行为现象之外，光尚未被认为直接影响海洋浮游动物的能量。在最近的研究中，我们发现了三种异养（非光合作用）原生生物直接利用光能消化浮游植物的证据。我们假设光通过食草动物食物液泡中活性氧的光敏形成来帮助浮游植物猎物的消化。然后，这种活性氧可以降解脂质和蛋白质，从质量上（通过产生更小、更容易吸收的化合物）和数量上（通过提供能量补充）补充消化。我们的数据表明光辅助消化可以产生 2？摄取率提高 10 倍，种群增长率提高 20 倍。在食物水平非常低的情况下，光辅助消化可以决定以浮游植物为食的异养原生生物的生存和严重死亡率。由于原生生物是海洋中浮游植物的主要消费者，光辅助消化对浮游植物消耗的调节、营养再生、营养转移效率和猎物选择具有深远的影响。我们建议研究光在调节原生生物放牧活动中的作用。拟议的研究将在多个生物学层面进行，从食草动物食物泡中的分子事件到整个微型浮游生物群落中浮游植物消耗的调节。拟议的研究集中在一个令人兴奋的概念上，即光作为一种基本的非生物资源，可以在猎物消化的基本水平上调节海洋主要食草动物的活动。原生生物的放牧、生长和生长效率与辐照度的直接耦合意味着这些速率和效率将以前所未有的方式随深度、纬度和季节而变化。此外，浮游植物种群与其主要消费者之间的耦合程度（群落结构和功能的基本决定因素）可能受到单一非生物资源的强烈介导，因此可能比以前认为的更接近。