Karmex Herbicide with Fertilization and Aeration to Control Filamentous Algae in Hatchery Ponds

Six 0.10-acre (0.04 ha) hatchery ponds containing striped bass flngerlings were treated with Karmex herbicide in an effort to control filamentous algae composed mainly of the genera Pithophora and Spirogyra. Ponds treated were fertilized and aerated immediately alter application of Karmex. Shortly after treatment with Karmex, large mats of filamentous algae floated to the surface, decayed, and were broken into fragments by agitation from aerators. The fragments settled to the pond bottoms. Dissolved oxygen concentrations dropped rapidly for several days following treatment, but remained above critical levels and then increased slowly. After 11 to 13 days dissolved oxygen concentrations at sunrise were above 8.0 mg/1 and aeration was discontinued. Dense phytoplankton blooms, believed to be a result of both fertilization and release of nutrients tied up in the filamentolls algae, developed 13 to 17 days after treatment with Kannex, and prevented new growths of filamentolls algae. Draining of ponds 44 to 97 days after treatment revealed no significant growths of filamentous algae.

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