Assessing the chemical speciation and bioavailability of iron regenerated by marine zooplankton

铁(Fe)是上层海洋中必需的，但往往是有限的营养物质。铁的来源包括外部输入，以及由于生物吸收和再生，包括通过浮游动物放牧，在地表水中铁的快速循环而导致的就地再生。浮游植物肠道中浮游植物生物量的消化预计会导致化学氧化还原和形态变化，这将影响铁的生物有效性，但这一循环过程仍未得到充分研究。目前的项目将通过一系列实验室和实地调查来审查这一专题，这些调查将探讨放牧对化学形态和生物有效性的影响。这些研究将调查不同浮游动物消化液泡/肠道中的pH和氧化还原状态，并检查如何捕食？牧草动态影响再生铁的形态及其对模型浮游植物培养的生物有效性。在由其他项目资助的巡航期间，现场实验还将使用沿海和开阔海域的天然捕食者组合来检查铁的再生、形态和生物有效性。该项目将通过比奇洛海洋实验室的项目，在缅因州的机构中教育和培训高中、本科生和博士后水平的学生和科学家。本科生将通过Bigelow REU计划参与学习。总体而言，该项目将通过侧重于这一重要研究领域的一个方面，提供关于海洋微生物吸收铁的来源和途径以及影响海洋水域生物有效性的因素的重要信息。

Iron (Fe) is a required, but often limiting nutrient, in the upper ocean. Sources of Fe include external inputs, as well an in situ regeneration due to the rapid recycling of Fe in surface waters through biological uptake and regeneration, including via zooplankton grazing. Digestion of phytoplankton biomass in zooplankton guts is expected to result in chemical redox and speciation changes which will affect Fe bioavailability, but this recycling process remains understudied. The current project will examine this topic through a series of laboratory and field investigations which will probe the consequences of grazing on chemical speciation and bioavailability. The studies will investigate the pH and redox state in the digestive vacuole/guts of different zooplankton, and examine how prey ? grazer dynamics influences the speciation of regenerated Fe, and its bioavailability to cultures of model phytoplankton. Field experiments will also examine Fe regeneration, speciation and bioavailability using natural prey - grazer assemblages from coastal and open ocean waters during cruises funded through other programs. The project will educate and train students and scientists at the high school, undergraduate and post-doctoral levels at institutions in Maine, and through programs at the Bigelow Marine Lab. Undergraduates will be involved in studies through the Bigelow REU program. Overall, the project will provide important information on the sources and pathways of iron uptake into marine microbes and the factors influencing bioavailability in marine waters by focusing on one aspect of this important research area.