Using sediment flocculation to reduce the impacts of Chesapeake Bay Microcystis aeruginosa harmful algal blooms

Abstract

Harmful algal blooms (HABs) are proliferations of phytoplankton in marine ecosystems. Cyanobacteria, often referred to as algae, are one of the many microorganisms capable of reaching bloom abundances. In recent years, HABs have increased in prevalence in the Chesapeake Bay due to eutrophication from nutrient and pollution runoff into the watershed. Our research focused on the mitigation of HABs, specifically blooms of Microcystis aeruginosa, a cyanobacterium that blooms annually in the upper Chesapeake and its tributaries. Our mitigation approach used sediment-flocculant mixtures to remove cyanobacteria cells from the water column. We explored the environmental impact of our efforts and the potential for indigenous grass restoration by incorporating submerged aquatic vegetation (SAV) seeds into our mitigation technique. Based on our data regarding efficacy, cost, environmental safety, and public opinion, we suggest mixtures consisting of local sediments and the flocculant chitosan for use in mitigating M. aeruginosa HABs in the Chesapeake Bay.