Skip to main content
ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Water Quality and Ecology Research » Research » Publications at this Location » Publication #415304
Research Project: Enhancing Long-Term Agroecosystem Sustainability of Water and Soil Resources Through Science and Technology

Location: Water Quality and Ecology Research

Title: Nitrogen fixation may not alleviate stoichiometric imbalances that limit primary production in eutrophic lake ecosystems

Author
item ANDERSEN, ISABELLE - Baylor University
item Taylor, Jason
item KELLY, PATRICK - Rhodes College
item HOKE, ALEX - Baylor University
item ROBBINS, CALEB - Baylor University
item SCOTT, JEFFERSON - Baylor University

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2024
Publication Date: 1/24/2025
Citation: Andersen, I.M., Taylor, J.M., Kelly, P.T., Hoke, A.K., Robbins, C.J., Scott, J.T. 2025. Nitrogen fixation may not alleviate stoichiometric imbalances that limit primary production in eutrophic lake ecosystems. Ecology. 106(1):e4516. https://doi.org/10.1002/ecy.4516.
DOI: https://doi.org/10.1002/ecy.4516

Interpretive Summary: Excess nutrients (nitrogen and phosphorus) from fertilizer and wastewater fuel algal blooms which can harm water quality, aquatic life, and ultimately human civilization. Efficiently managing harmful algal blooms is limited by a long held assumption that phosphorus alone drives algal blooms. We conducted a long-term pond fertilization experiment that demonstrates that nitrogen can be a persistent driver of maximum algal bloom dynamics in systems that have a history of phosphorus enrichment. This is because phosphorus sticks around in lake ecosystems, natural process that bring nitrogen into systems do not keep up with levels of phosphorus, and excess nitrogen is processed by microbes, creating a persistent need for nitrogen. Thus, strategies that prevent nitrogen, in addition to phosphrous, from entering lakes and rivers may reduce harmful algal blooms.

Technical Abstract: Nitrogen (N) and phosphorus (P) availability can limit primary productivity and ecosystems with low N inputs relative to P may “evolve” P limitation over time, due to biological N2 fixation compensating for N deficiency. However, numerous ecosystem processes may constrain the effect of N2 fixation. Here we used a three-year replicated mesocosm experiment representing shallow eutrophic lakes with a wide range of N:P inputs to assess the capacity for evolving P limitation. Despite N2 fixation contributing as much as 80% of reactive N, low N treatments had less phytoplankton biomass than high N treatments. Furthermore, the seasonal increase of N imbalance relative to P in the low N treatments did not carry over annually. Cumulatively, these findings indicate that N accumulation from N2 fixation was insufficient to trigger a transition to P limitation seasonally or within our three-year experiment.