Quantifying Temperature Dependence In Growth & Grazing Rates of Planktonic Herbivores

浮游生物是生活在世界海洋中的单细胞生物，它们负责产生氧气，在大气和深海之间循环能量和物质，是几乎所有海产品的基础。这些赋予生命的功能在很大程度上取决于浮游生物生长和被吃掉的相对速度。温度如何影响这些速率对于了解浮游生物对环境变化和海洋动力学的反应至关重要。众所周知，浮游生物在温度较高时生长得更快，然而，摄食是否也有类似的温度依赖性尚不清楚。这意味着海洋学家缺少建立全球预测模型所需的关键数据。该项目将填补基本的知识空白，并测量单细胞浮游动物在代表全球海洋的温度梯度中的生理速率，从极地到热带地区，以及整个季节周期。研究人员将把实验室实验与从沿海海洋（纳拉甘西特湾）采集的标本结合起来，这是季节性温度变化强烈的典范。这些数据将清楚地说明全球动态海洋中浮游生物的生产能力和活动。该项目支持一名早期职业科学家，以及研究生和本科生。科学家们将继续通过大规模的外展活动、高中水平的教育以及通过网络和其他媒体的参与向公众传播他们的研究。此外，研究人员将继续与梅特卡夫海洋与环境报告研究所合作，支持他们为记者举办的年度科学浸入式研讨会，以及他们通过网络研讨会传播研究成果的持续工作。放牧是海洋初级生产的最大单一损失因子，因此影响全球有机和无机物库之间的关键转移速率。值得注意的是，草食性原生生物的生长和放牧率的数据在广阔的极地地区和冬季和春季期间都是非常稀少的。通过将实验室实验与地面实地调查相结合，该项目缓解了海洋学的核心知识缺口，并提供了必要的经验测量，以推导出将异养原生生物生长和放牧率的温度依赖性纳入生物地球化学模型的算法。利用温带沿海河口（纳拉甘西特湾）异常的季节温度波动来测量在不同温度和季节分离的异养原生生物的比率，并量化这些生态型的温度和适应反应。该项目提供了迫切需要的数据，以解决以下难题：草食性生长和捕食是否在低温下受到抑制，这意味着低营养转移率和高碳出口，或者是否捕食的速度与温带系统相当，初级生产大部分被捕食所损失。全球海洋的大温度梯度意味着跨生物群系和生物地球化学模式对模拟速率过程中温度依赖性的假设特别敏感。建立异养浮游生物生理速率（生长和放牧）对温度梯度的依赖性，模拟浮游生物在变化的海洋中所经历的现实条件，是整合生物地球化学建模工作中急需的生物信息的关键一步。该项目通过提供原生生物草食和生长速率的温度依赖性、全球生物地球化学循环中有机质转化的关键过程以及生态系统模型中严重缺失的工具，为将生态学研究与生态系统模型联系起来做出了重大贡献。

Plankton, single-celled organisms that inhabit the world's oceans are responsible for the generation of oxygen, cycling energy and matter between the atmosphere and the deep ocean and are the basis for virtually all seafood harvested. These life-giving functions critically depend on the relative rates at which plankton grow and get eaten. How temperature influences those rates is essential to understand plankton responses to environmental changes and ocean dynamics. It is well established that plankton grow faster when temperatures are higher however, whether feeding has a similar temperature dependence is unknown. That means oceanographers are missing key data required to build global predictive models. This project will fill essential knowledge gaps and measure physiological rates of singled celled zooplankton across temperature gradients representing the global ocean, from polar to tropical regions and throughout the seasonal cycle. Researchers will combine laboratory experiments with specimens taken from the coastal ocean (Narragansett Bay), which is exemplary in its strong seasonal temperature variations. These data will provide a clear picture of the production capacity and activity of plankton in a global and dynamic ocean. The project supports an early career scientist, as well as graduate and undergraduate students. Scientists will continue communicating their research to the public through large-scale outreach events, education at the high-school level, and engagement through online and other media. Moreover, researchers will continue collaborating with the Metcalf Institute for Marine & Environmental Reporting to support their Annual Science Immersion Workshop for Journalists and their ongoing work to disseminate research findings through web-based seminars.Grazing is the single largest loss factor of marine primary production and thus affects a key transfer rate between global organic and inorganic matter pools. Remarkably, data for herbivorous protist growth and grazing rates at temperatures representative of the vast polar regions and during winter and spring periods are extremely sparse. By combining laboratory experiments with ground truthing fieldwork, this project alleviates a central knowledge gap in oceanography and delivers the empirical measurements necessary to derive algorithms to incorporate temperature dependence of heterotrophic protist growth and grazing rates into biogeochemical models. The extraordinary seasonal temperature fluctuations in a temperate coastal estuary (Narragansett Bay) are exploited to measure rates of heterotrophic protists isolated from different temperatures and seasons and to quantify the temperature and acclimation responses of these ecotypes. This project delivers data urgently needed to solve the conundrum of whether herbivorous growth and predation is depressed at low temperatures, implying low trophic transfer rates and high carbon export, or if predation proceeds at rates comparable to temperate systems with primary production largely lost to predation. Large temperature gradients in the global ocean mean that cross-biome and biogeochemical models are particularly sensitive to assumptions about the temperature dependence in modeled rate processes. Establishment of the dependence of heterotrophic plankton physiological rates (growth and grazing) to gradients of temperature, mimicking realistic conditions experienced by plankton in a changing ocean, is a key step towards integrating much needed biological information in biogeochemical modeling efforts. This project makes a significant contribution to linking ecological research with ecosystem models by providing empirically rooted algorithms of the temperature dependence of protistan herbivory and growth rates, key processes in the transformation of organic matter in global biogeochemical cycles and tools critically missing in ecosystem models.