The relative effects of algaecides and nanobubble ozone treatment (NBOT) on nontarget zooplankton in a mesocosm study

Stanislawczyk K, Braig IV EC, Laughinghouse IV HD, Raymond HA, Syed HE, Fuchs JD, Weavers LK, Chaffin JD. 2026. The relative effects of algaecides and nanobubble ozone treatment (NBOT) on nontarget zooplankton in a mesocosm study. Lake Reserv Manag. XXX–XXX.Cyanobacterial harmful algal blooms (cyanoHABs) threaten recreational and drinking water sources, and lake managers need tools that suppress or control them with minimal negative effects on nontarget organisms. Nanobubble ozone technology (NBOT) is an emerging cyanoHAB control strategy, but documentation of effects on nontarget zooplankton is limited. Using a zooplankton community sourced from Lake Erie, this study compared replicated mesocosm trials of 2 NBOT treatments (0.9 and 4.6 mg O3/L) to 2 algaecides: registered copper (1 mg Cu/L) and hydrogen peroxide-based (10 mg H2O2/L) applied at label-approved amounts. Both algaecides had significantly (P < 0.01) greater negative effects on nontarget zooplankton than the 2 NBOT doses. Response to treatment was variable among the 7 evaluated taxa. Bosmina sp., Daphnia sp., Sididae, and Chydoridae increased in both controls and lower NBOT treatments but significantly (P < 0.01) declined in the algaecide treatments. The higher NBOT dose treatment reduced Bosmina sp. but to a lesser extent than algaecide treatments. Additional studies are needed to determine the effect of increased ozone doses on zooplankton communities. Overall, NBOT is a viable cyanoHAB treatment alternative with the potential to reduce negative effects on nontarget zooplankton compared to traditional algaecides.