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

铁（Fe）是海洋上层必需的，但通常是有限的营养物质。铁的来源包括外部输入，以及通过生物吸收和再生（包括通过浮游动物放牧）在地表水中快速循环的铁的原位再生。浮游动物肠道对浮游植物生物量的消化会导致化学氧化还原和物种形成变化，从而影响铁的生物利用度，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研究这一主题，这些调查将探讨放牧对化学物种形成和生物利用度的影响。这些研究将调查不同浮游动物消化液泡/肠道中的pH值和氧化还原状态，并研究猎物如何？食草动物动态影响再生铁的种类形成及其对模式浮游植物培养物的生物可利用性。实地实验还将考察铁的再生、物种形成和生物利用度，在其他项目资助的巡航期间，利用来自沿海和开阔海域的天然猎物-食草动物组合。该项目将通过毕格罗海洋实验室的项目，对缅因州各机构的高中、本科和博士后阶段的学生和科学家进行教育和培训。本科生将通过毕格罗REU项目参与研究。总体而言，该项目将通过关注这一重要研究领域的一个方面，为海洋微生物对铁的吸收来源和途径以及影响海水生物利用度的因素提供重要信息。

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.