Physiological ecology of algal iron acquisition

本研究的主要目的是更好地了解藻类获得铁的机制，以及不同的机制如何影响水生生态系统（特别是淡水）的功能。 铁与藻类之间的相互作用可能对调节淡水和海洋水生环境的生产力具有重要意义，也可能影响水生系统的藻类物种组成。 尽管铁是地壳中最丰富的元素之一，尽管被归类为植物和藻类生长的“微量营养素”（仅需少量），而不是“常量营养素”（例如氮），但铁的可用性限制了许多陆地和水生生态系统的生产力。 铁限制可能是由于环境中的铁含量低，铁的生物利用度低，或这两种因素的组合而发生的。 海洋的“高营养低叶绿素”区被认为受到风介导的铁沉积速率的限制，而一些淡水系统含有与有机分子紧密结合的铁，限制了生物可用性。 HNLC区的铁限制对藻类（浮游植物）生物量设定了上限，从而对这些区域的光合作用二氧化碳吸收率设定了上限。 藻类光合作用从大气中去除二氧化碳，这一问题对于目前对全球气候变化的关切尤为重要。 铁调节淡水系统的生产力的重要性已较少调查比在海洋系统中，但很明显，铁结合溶解有机物可以减少铁的生物可用性，并降低藻类生长的速度。 藻类光合作用是大多数淡水系统的最大能量输入，因此铁限制对淡水水生生态系统生产力具有潜在的重要调节作用。 该研究将侧重于淡水藻类物种从环境中获得铁的不同机制，以及铁的生物有效性如何与各种铁获取机制相互作用，以影响铁的吸收程度和物种对不同形式的水生铁的反应。

The major objective of this research is to gain a better understanding of the mechanism(s) of iron acquisition by algae, and how the different mechanisms may affect the functioning of aquatic ecosystems (especially freshwater).  The interactions between iron and algae may have implications for regulating the productivity of both freshwater and marine aquatic environments, and also may affect the algal species composition of aquatic systems.       Despite being one of the most abundant elements in the earth's crust, and despite being classified as a "micronutrient" (needed in only small amounts) for plant and algal growth, rather than as a "macronutrient" (for example, nitrogen), iron availability limits productivity of many terrestrial and aquatic ecosystems.  Iron limitation may occur as a result of low amounts of iron in the environment, low biological availability of iron, or a combination of both of these factors.  The "high nutrient low chlorophyll" (HNLC) zones of the oceans are postulated to be limited by the rate of wind-mediated deposition of iron, while some freshwater systems contain iron tightly bound to organic molecules, limiting the biological availability.     Iron limitation in the HNLC zones sets an upper limit on algal (phytoplankton) biomass, and thus sets an upper limit on the rate of photosynthetic carbon dioxide uptake in those regions.  Algal photosynthesis removes carbon dioxide from the atmosphere, an issue that is particularly important in relation to current concerns about global climate change.     The importance of iron regulation of the productivity of freshwater systems has been less investigated than in marine systems, but it is clear that iron binding by dissolved organic matter can reduce biological availability of iron and decrease the rate of algal growth.  Algal photosynthesis represents the largest input of energy into most freshwater systems, thus iron limitation has potentially important regulatory effects on freshwater aquatic ecosystem productivity.     The research will focus on the different mechanisms by which freshwater algal species obtain iron from the environment, and how the biological availability of iron may interact with the various iron acquisition mechanisms to affect the degree of iron uptake and the species responses to different forms of aquatic iron.