CAREER: Beyond N and P: How trace metal limitation influences stream ecosystem function

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Algae covering the bed of stream ecosystems provide key food resources for invertebrates and fishes and can intercept pollutants. Algae grow rapidly when provided with light and a balanced supply of nutrients, and a lack of resources causes slow growth and inefficient filtering of pollutants. Algae require dozens of nutrients, but only two major nutrients (nitrogen and phosphorus) have been extensively studied in streams. Recent work in the ocean and large lakes has shown that trace metals are important for the growth of algae. This project will provide fundamental understanding of the role of trace metals in the growth of stream algae and explore the consequences of trace metal deficiencies on pollution filtering. This work will also provide experiences for high school and undergraduate students that promote key skills required of modern biology. Modern biology incorporates knowledge from many other scientific fields and this work’s study of trace metals provides an interdisciplinary approach that can be a model for developing scientists.This project will use experiments from the patch to stream scale to study the extent, cause, and consequences of trace metal deficiency for stream ecosystem structure and function. The project will answer three fundamental questions: (1) How often do trace metals influence algae growth in Great Lakes streams?, (2) How does changing the nutrient balance alter algal communities?, and (3) How does changing trace metal availability alter pollution filtering by algae? The study will use nutrient diffusing substrates (NDS) in 98 Great Lakes streams to identify locations and conditions where trace metals are influencing algae. Ensuing studies will measure algal communities and pollutant uptake rates under different trace metal conditions. Results at the patch scale will be confirmed at the whole stream scale with experiments in artificial channels and divided streams. The project will use NDS experiments in classrooms and laboratories to give high school and undergraduate students authentic research experiences. The researchers will work with the Kent State Upward Bound Math Science program to introduce high school students to interdisciplinary science and provide them with authentic, place-based research experiences in their local streams.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.