Microbiological and physicochemical characteristics of pond sediment and methods for improving oxygenation of the soil-water interface
1997
Boyd, Claude E.(Auburn University, Alabama (USA). Dept. of Fisheries and Allied Aquacultures)
Sediment in aquaculture ponds can be separated into horizons (layers). Beginning at the upper surface, there is a flocculent layer, a layer of high-water content that is relatively-well mixed, a layer of mature, bulk sediment, a transitional layer, and the original, undisturbed soil. Particles of mineral soil and organic matter originating from internal and external sources are continually settling to the bottom. Microbial and chemical activity are much greater in the flocculent layer and in the underlaying mixed layer than in deeper layers. The large input of organic matter to the sediment in feces, uneaten feed, and dead phytoplankton causes a high oxygen demand in the surface sediment, and at best, oxygenated conditions extend only a few millimeters below the soil-water interface. At worst, the soil-water interface becomes anaerobic, and potentially toxic microbial metabolites and reduced products of chemical reactions can enter the pond water. Potential methods for improving oxygenation of the soil-water interface include aeration, augmentation of microbial populations or enzymes, improving soil properties by liming, and application of chemical oxidants. Of course, better pond management to reduce organic matter inputs to the sediment also are important.
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