Characterizing a cyanobacteria-driven regime shift within Lake Mattamuskeet, NC using long-term monitoring datasets

Mattamuskeet National Wildlife Refuge houses the largest natural lake in North Carolina. Historically, this shallow lake was dominated by submerged aquatic vegetation (SAVs) and was an important feeding ground for migratory birds along the Atlantic Flyway. In the 1940s, HWY 94 was built through the middle of the lake, splitting the lake into two basins that have since shifted between alternative ecosystem states independently of one another. In recent years, the lake’s health has been further degraded by a lack of drainage, invasive common carp, and excessive nutrients from surrounding agricultural fields. These stressors forced a regime shift in the past decade. Today, the lake is absent from SAVs and is instead dominated year-round by small, filamentous cyanobacteria (Raphidiopsis and Komvophoron). High phytoplankton biomass (~100 μg Chl a L⁻¹) creates steep light attenuation that prevents re-establishment of SAVs. To identify the physical, chemical, and biological factors driving this shift and characterize the lake’s response to anthropogenic stress, we will analyze multiple long-term monitoring datasets from within the lake beginning in 2012. This data will be supplemented by our own monitoring program which began in January 2023 and utilizes twice-monthly samplings to measure parameters such as phytoplankton biomass, community composition, nutrient availability, and light attenuation. Together, this comprehensive analysis will provide insights into the ecological impacts of human activity on Lake Mattamuskeet to inform future restoration efforts.

Presentation Preference: Either

Primary Presenter: Mary Kate Rinderle, University of North Carolina--Chapel Hill (rinderle@unc.edu)

Authors:

Mary Kate Rinderle, University of North Carolina--Chapel Hill  (rinderle@unc.edu)

Nathan Hall, University of North Carolina--Chapel Hill  (nshall@email.unc.edu)