Dissertation Research: Phosphorus Cycling in Shallow Freshwater Ecosystems

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Phosphorus is a nutrient required by all living things, but its use in industrial fertilizers and other products has increased its occurrence to polluting levels in many agricultural and urban watersheds. Excess phosphorus often causes eutrophication in freshwater ecosystems. Eutrophication remains a pervasive problem in the U.S. and can impact aquatic ecosystems as blooms of toxic phytoplankton, reduced water clarity, changes in plant communities, and fish kills. Due to the ability of the sediments to accumulate phosphorus, wetlands are often managed to store phosphorus and prevent entry into downstream ecosystems. The ability of wetland sediments to bind phosphorus varies, and at times wetlands can become sources of, rather than sinks for, phosphorus. The ways in which phosphorus binds to and is released from sediments has been studied extensively in deep lakes, but less so in shallow wetlands. Shallow wetlands differ from lakes in that they often dry and re-flood and tend to have sediments with more organic matter (decomposing plant material). This study investigates how water level fluctuations influence phosphorus binding and release in wetland sediments of varying characteristics.The findings of this research will not only inform understanding of how sediment controls plant growth in freshwater ecosystems through P release, but will have direct applications to management of many freshwater ecosystems. The findings of this research will provide insight into how best to manage wetlands to promote phosphorus accumulation in sediments and prevent its release to downstream ecosystems. In addition to management implications of the research itself, researchers will educate the general public through development of K-12 curricula aimed at teaching the definition, ecology, and functional roles of wetlands and wetland sediment. Lesson plans will be developed through a partnership with teachers at Lawton Community Schools in Southwest Michigan, and will be taught to students there with direct assessment of student learning. Assessments of student learning from lesson plans will aide in refining lesson plans for publication in education literature. Finally, undergraduate students interested in ecology will be given opportunities to conduct independent research experiences as part of this project.