Grant: Discovery Grants Program - Individual

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.