Effects of Smallmouth Buffalo and Potassium Permanganate Treatment on Plankton and Pond Water Quality

Abstract

There is recent interest in using smallmouth buffalo Ictiobus bubalus and treatment with potassium permanganate (KMnO₄) to control Dero digitata, the aquatic oligochaete host involved in the life cycle of proliferative gill disease. To complement those investigations, we determined the changes in water quality, phytoplankton, and zooplankton resulting from KMnO₄ treatment and stocking of smallmouth buffalo into nursery ponds for channel catfish Ictalurus punctatus; we did not evaluate the attendant control effectiveness on Dero spp. Stocking buffalo at a rate of 75/ha in nursery ponds did not cause changes in water quality, nutrients, or zooplankton concentrations. Ponds treated with KMnO₄ (applied at 57 g/ha when partially filled to about 30 cm deep) contained higher total dissolved solids (230 mg/L) than untreated ponds (204 mg/L). Phytoplankton and zooplankton concentrations in the KMnO₄ ponds increased 2−5 weeks after application compared with the control ponds. The observed changes in KMnO₄ ponds may be related to nutrient regeneration through oxidation by KMnO₄ or may indicate that potassium is a limiting nutrient for phytoplankton in these ponds. The increase in green algae, diatoms, and copepods would be beneficial to catfish fry culture because these algae blooms are desirable over cyanobacteria blooms and copepods are a preferred food resource of catfish fry.