title: The effects of three chemical algaecides on cell numbers and toxin content of the cyanobacteria Microcystis aeruginosa and Anabaenopsis sp.
abstract: Toxic cyanobacteria blooms are a growing concern for public health and safety, due in part to the production of the hepatotoxin microcystin by certain species, including Microcystis aeruginosa. Management strategies for controlling cyanobacteria blooms include algaecide treatments, often with copper sulfate, and more recently oxidizers such as sodium percarbonate that produce hydrogen peroxide. This study assessed the effects of two copper-containing algaecides and one sodium percarbonate-containing algaecide on mitigating cell numbers and toxin content of cultured M. aeruginosa and summer (July) bloom samples of Anabaenopsis sp. in a brackish stormwater detention pond. Monitoring of the bloom revealed that Anabaenopsis sp. was associated with elevated levels of orthophosphate compared to nitrogen (dissolved inorganic nitrogen to phosphorus ratios were 0.19-1.80), and the bloom decline (September-October) was likely due to lower autumn water temperatures combined with potential grazing by the dinoflagellate Protoperidinium quinquecorne. Laboratory-based algaecide experiments included three dose levels, and cyanobacteria cell numbers and microcystin concentrations (particulate and dissolved) were evaluated over 7 d. Following exposure, copper-containing treatments generally had lower cell numbers than either sodium percarbonate-containing or control (no algaecide) treatments. Addition of algaecides did not reduce overall microcystin levels, and a release of toxin from the particulate to dissolved phase was observed in most treatments. These findings indicate that algaecide applications may visibly control cyanobacteria bloom densities, but not necessarily toxin concentrations, and have implications for public health and safety.
authors: Belle W. Baruch Institute for Marine and Coastal Sciences, University of South Carolina, Hollings Marine Laboratory, 331 Fort Johnson Road, Charleston, SC, 29412, USA, dgreenfield@belle.baruch.sc.edu.
authors: Dianne I
authors: DI
authors: Greenfield
authors: Ashley
authors: A
authors: Duquette
authors: Abby
authors: A
authors: Goodson
authors: Charles J
authors: CJ
authors: Keppler
authors: Sarah H
authors: SH
authors: Williams
authors: Larissa M
authors: LM
authors: Brock
authors: Krista D
authors: KD
authors: Stackley
authors: David
authors: D
authors: White
authors: Susan B
authors: SB
authors: Wilde
mesh_terms: D002254:Carbonates / Q000494:pharmacology; D019327:Copper Sulfate / Q000494:pharmacology; D000458:Cyanobacteria / Q000187:drug effects* / Q000254:growth & development; D057097:Harmful Algal Bloom / Q000187:drug effects*; D052998:Microcystins / Q000032:analysis; D046931:Microcystis / Q000187:drug effects* / Q000254:growth & development; D009584:Nitrogen / Q000032:analysis; D010575:Pesticides / Q000494:pharmacology*; D010710:Phosphates / Q000032:analysis; D011156:Population Density; D054712:Salinity; D013022:South Carolina
chemical_list: D002254:Carbonates; D052998:Microcystins; D010575:Pesticides; D010710:Phosphates; C078588:microcystin; D019327:Copper Sulfate; D009584:Nitrogen; C034738:sodium percarbonate