Comparison of Three Algaecides for Controlling the Density ofPrymnesium parvum¹

Abstract

Prymnesium parvum has become more prevalent in water resources of the southern United States. As the potential impacts of P. parvum are relatively well known, especially its capability to severely affect fish, managers have sought efficacious, environmentally sound, and socially acceptable strategies for mitigating this noxious species. Laboratory testing was used to identify an effective algaecide for control of P. parvum from Texas, Arizona, Florida, North Carolina, and South Carolina. Cutrine Ò -Plus at 0.2 mg Cu ⁄ l significantly decreased the density of P. parvum in samples from all of these locations. Both copper sulfate and Phycomycin Ò were less effective for controlling the population growth of P. parvum. The predicted response from the laboratory study was confirmed in the field at the Arizona site. Strategic use of Cutrine Ò -Plus in larger water resources could provide toxin-free refugia to allow some fish to survive and repopulate the water resource when the golden alga infestation abates.

Management of Target Algae by Using Copper-Based Algaecides: Effects of Algal Cell Density and Sensitivity to Copper

“…In addition to this study, Rodgers et al (2010) also found that copper-ethanolamine complex was more effective for controlling the problematic alga Prymnesium parvum at 10 3 -10 4 cells/mL than copper sulfate in laboratory studies. Importantly, copper concentration and formulation play important roles for controlling problematic algae.…”

“…For example, noxious algae P. parvum has been related with fish kills in brackish inland waters (Lindholm et al, 1999;Roelke et al, 2010;Brooks et al, 2011;Umphres et al, 2012). Rodgers et al (2010) reported that the margin of safety for P. promelas and freshwater invertebrate Ceriodaphnia dubia after 96-h exposure to CutrinePlus required for controlling P. parvum was 4.3 and 0.6, respectively. Under this circumstance, authorities considering applications of copper formulations for controlling problematic algae will have to consider the relative risks of controlling problematic algae.…”

“…Toxicity of copper compounds to algae can be due to several forms, such as cupric ion hydroxy-or carbonate-Cu (Flemming and Trevors, 1989). Several studies have shown that exposures of different forms of copper-based algaecides cause different responses in target algal species (Murray-Gulde et al, 2002;Rodgers et al, 2010;Bishop and Rodgers, 2012). When copper compounds are used as aquatic algaecides, the cupric ion is usually bound by chelators (e.g., ethanolamine or citrate) to prevent precipitation or complexation from ions in water, which could have influences on the algaecide effectiveness for controlling algal growth.…”

Effects of two copper compounds on Microcystis aeruginosa cell density, membrane integrity, and microcystin release

“…Since exposures of copper-based algaecides cause different responses by target algal species (Murray-Gulde et al, 2002;Rodgers et al, 2010;Bishop and Rodgers, 2012;Calomeni et al, 2014), laboratory predictions of responses of M. aeruginosa to exposures of copper-based algaecides can provide important information regarding the consequences of using copper-based algaecides for reliable and substantial reduction of M. aeruginosa blooms. Additionally, measurements of extracellular microcystin concentrations can indicate the post-treatment release of this endotoxin, and measurements of total microcystin concentrations are used to make risk-based decisions regarding the utilization of water resources.…”

Evaluation of the utility of six measures for algal (Microcystis aeruginosa, Planktothrix agardhii and Pseudokirchneriella subcapitata) viability

“…Cell densities were determined using a Leitz Wetzlar Dialux 20 light microscope (Leitz USA Scopes, Paramount, California) and an Improved Neubauer Hemocytometer at 250x magnification (Rodgers et al, 2010). P. agardhii cell densities were estimated by counting the number of trichomes per 0.2 mm 2 gridded area on the hemocytometer and multiplied by the number of cells (12 cells) spanning this gridded area.…”