Author: Nayeli K Sanchez,   (The Ohio State University)

Description:
Understanding the interactions of multiple environmental stressors on ecosystem functioning and water quality in rivers is critical for effective watershed management. Here, we examine the effects of multiple environmental stressors on algal community structure throughout streams and reservoirs in seven catchments representing agricultural, forested and mixed land uses in Ohio, Kentucky and Indiana, USA. From 2018-2019, we quantified nitrogen and phosphorus concentrations, measured physicochemical water-quality parameters, and determined nitrogen-to-phosphorus (N:P) ratios for all sites. In streams, we measured streamflow velocity and temperature regimes, and assessed physical channel alterations by evaluating bank and bed stability. We also examined algal biomass, absolute abundance of phytoplankton taxa, and fluorometrically assessed the relative abundance of major algal classes. Microcystin toxin production and extracellular release was assessed using Solid Phase Adsorption Toxin Tracking (SPATT). We observed substantial spatial variability; for example, DIN:DIP ratios averaged 86.92 ± 118.83 in agricultural catchments, followed by 62.87 ± 256.94 in mixed-use, and 18.82 ± 31.29 in forested catchments. We predict that nutrients, temperature, and physical habitat characteristics will interact to influence the presence of distinct algal assemblages and microcystin production. We anticipate that our findings will provide important information on the drivers of algal-community dynamics in watersheds of the upper Ohio River basin, including harmful algal blooms.

Category: Scientific Program Abstract > Special Session > CS18 Harmful blooms