Wetlands provide 40% of global ecosystem services despite covering just 1.5% of Earth's surface. However, wetlands are disproportionately threatened by human development, pollution, and climate change. Alabama is home to a variety of wetland types, each harboring unique flora and fauna, including blackwater wetlands. These wetlands are typically associated with blackwater streams that originate below the fall line, with increased tannins, organic matter, and acidity. The Alabama Department of Environmental Management (ADEM) is responsible for monitoring surface waters, including blackwater wetlands, yet full incorporation of wetland monitoring has been difficult. To assist in these efforts, we are establishing baseline reference conditions for aquatic macroinvertebrates in blackwater systems in southwest Alabama.
Seventeen stream/wetland systems were selected based on stream pH, color, and conductivity in southwest Alabama to establish a tannic gradient (13 sites along the gradient and four sites as alluvial outgroup). Macroinvertebrates were sampled during summer 2025 in the streams of each system in all available habitat types using d-nets according to ADEM protocols. Physicochemical were collected during stream sampling this previous summer (temperature, pH, conductivity, dissolved oxygen, and color) along with habitat conditions (discharge, flow and depth, organic matter content, and sediment profiles). Macroinvertebrates are currently being processed, and wetland sampling will commence in spring 2026.
Relationships between abiotic conditions and biotic communities will be visualized using nonmetric multidimensional scaling (NMDS), and differences between blackwater and alluvial systems will be quantified using permutational analysis of variance (PERMANOVA). Linear mixed-effect models will be used to describe macroinvertebrate metrics (e.g., diversity, richness, etc.) along the tannic gradient. From these results, taxonomic and functional baseline criteria will be established for improved, targeted monitoring and assessment through ADEM as well as for groundwork for future studies in these unique systems.