Theses and Dissertations

Title: Preliminary investigations on control of Microcystis in fish ponds

Name: Crance, Johnie Hampton

Degree: MS

Chair: Dr. John M. Lawrence

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1958

Pages: 72

Keywords: Microcystis,Copper sulfate,Fish ponds,Monuron,Dichlone.


In Alabama, dense blooms of Microcystis have been responsible for loss of income to commercial pond owners. During the period from July 27 to November 15, 1957, copper sulfate was applied at rates from 0.7 to 0.8 pound per surface acre to five ponds for control of Microcystis. Total hardness of the pond waters ranged from 32 to 46 p.p.m. (as CaCO3). Successful results were obtained by suspending cloth bags containing fine crystals of the chemical 0.5 foot beneath the surface water. One bag was used for each 2.5 to 13 acres of surface water. The alga reappeared in abundance in all of the ponds within 25 days. In most cases, the number of zooplankters increased appreciably within 6 to 10 days following an application of copper sulfate and declined as the Microcystis repopulated the pond. Decay of the alga following applications of copper sulfate did not cause an oxygen deficiency harmful to fish in the ponds. There was no correlation between the abundance of Microcystis and the concentration of nitrogen, phosphorus, or calcium in the pond waters.A concentration of 0.5 p.p.m. 2,3-dichloro-1,4-napthoquinone (dichlone) killed a dense bloom of Microcystis in an earthen pond, but no control was obtained with 0.2 p.p.m.. Concentrations of 0.25 and 0.15 p.p.m. dichlone were toxic to over 90 percent of the bluegills, Lepomis macrochirus Raf., (2.5 to 3.5 inches total length) and largemouth bass, Micropterus salmoides Lac., (3.5 to 4.5 inches total length) respectively, in earthen ponds. Dichlone at a concentration of 0.05 p.p.m. was toxic within 120 hours to over 90 per cent of the bluegills and bass in glass aquaria. A concentration of 1.0 p.p.m. 3-(p-chlorophenyl)-1,1-dimethylurea (monuron) did not control Microcystis in earthen ponds. Monuron at a concentration of 80 p.p.m. was not toxic within 380 hours to bluegills in glass aquaria.

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