Reversing Course: Ecosystem Restoration, Geoengineering, and Algal Bloom Mitigation

Controlling algal blooms is difficult, and many approaches are controversial. Systems are resistant to change. Returning to a pre-eutrophied or pre-impacted state and reversing ecological damage may take time and a range of trajectories. Nutrient reductions are typically necessary, but single nutrient reduction strategies may further alter ecosystems due to stoichiometric changes. To mitigate algal blooms in real time, physical, chemical, and biological control methods are advancing but may have secondary effects, require extensive permitting, and/or may simply be impractical or too expensive to implement. While virtually all of these approaches have impracticalities when large blooms arise, some of these methods may be feasible, and in fact are being used, on small scales or in aquaculture settings.