Limnology of Three Farm Ponds in South-Central South Dakota

Physical, chemical, and biological aspects of three farm ponds in south-central South Dakota were studied from June 1964 until December 1965. Maximum water temperature at the surface reached 25.2 C, while water temperatures at the bottom of the ponds were about 2 to 4C lower than the surface. Light transmission was influenced by turbidity but generally penetrated to the bottom of the ponds except during periods of cloudy ice and snow cover. Dissolved oxygen was near saturation during periods of open water. Most chemical ions in the ponds increased annually from a winter minimum to a spring maximum. Total dissolved solids were high, with one pond reaching 3510 ppm. Dominant order of anions was sulfates, carbonates, and chlorides, while cations were sodium, calcium, magnesium, and potassium. Nitrates, phosphates, and iron were never a limitin factor in primary production. Phytoplankton population were dominated by a blue-green algae, Microcystis, which reached a maximum population of 9.3 cc/m3. Maximum primary production recorded was 0.78 gms/m2/day. Copepods in the ponds constituted approximately 75% of the total zooplankton, while cladocerans constituted 15%, and rotifer 10%