Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: December 16, 2005
Publication Date: February 13, 2006
Citation: Green, B.W. 2006. Effect of mechanical pond circulation on dissolved oxygen and temperature profiles in channel catfish ponds [abstract]. Aquaculture America 2006 Book of Abstracts. p. 116.
Phytoplankton are the primary producers and consumers of dissolved oxygen in earthen channel catfish (Ictalurus punctatus) production ponds. In a pond with a dense plankton bloom, dissolved oxygen (DO) concentration can become supersaturated during daylight hours and fall to 10% of saturation or less during the night. Exposure to low DO concentration can reduce fish growth and in extreme cases, result in fish mortality.
Most oxygen production during intense photosynthesis occurs in the upper strata of the pond because self-shading limits plankton production at greater depths. Circulating pond water during the day may retain photosynthetically produced DO that may otherwise be lost to the atmosphere when DO concentration is supersaturated. Two types of pond circulator were tested in 0.1-ha earthen ponds stocked with channel catfish for multiple-batch culture. Estimated catfish biomass in ponds during the trial was 8,200 kg/ha. Each pond was equipped with an electric paddlewheel aerator (0.373 kW) that was activated when pond DO concentration was 4.0 mg/L or less. A low-revolutions-per-minute (approximately 6 RPM) horizontal discharge circulator and a vertical discharge circulator were tested. Both circulators operated continuously. Control ponds were equipped with only the paddlewheel aerator. Dissolved oxygen concentration and temperature profiles to 75-cm depth were more uniform in horizontally and vertically circulated ponds compared to control ponds. Nighttime aeration required was 9% less in horizontally circulated ponds only, which indicates that some photosynthetically produced dissolved oxygen had been captured.