Yont Musig

ORTHOPHOSPHATE UPTAKE BY PHYTOPLANKTON AND SEDIMENT

Abstract Planktonic communities in samples of water from fish ponds absorbed 5 to 100% (ave. = 41%) of 0.30 mg/l additions of orthophosphate within 24 h. Sediments from fish ponds in different edaphic regions and from different depths in ponds removed 70 to 90% of 0.30 mg/l additions of orthophosphate to the overlaying water. The sediment-water systems represented a wide range of environmental conditions, but the rates of phosphorus uptake were similar for all systems. Phosphorus loss rates from earthen ponds and sediment-water systems in plastic pools were similar to those observed in laboratory systems.

EFFECTS OF THREE PHOSPHORUS FERTILIZERS ON PHOSPHORUS CONCENTRATIONS AND PHYTOPLANKTON PRODUCTION

Abstract Results of studies in earthen ponds and mud-water systems in plastic pools indicated that applications of liquid phosphorus fertilizer were more effective in increasing phosphorus concentrations and phytoplankton production than broadcast applications of triple superphosphate and diammonium phosphate. The effectiveness of triple superphosphate was increased by dissolving it in water before application.

Effect of salinity on oxygen transfer by propeller-aspirator-pump and paddle wheel aerators used in shrimp farming

Abstract Propeller-aspirator-pump aerators transferred oxygen to water more efficiently at salinities of 10–30 ppt than at lower salinities. Oxygen transfer by Taiwan-style paddle wheel aerators was unaffected by salinity in the range of 0–30 ppt. One brand of propeller-aspirator-pump aerator had an aeration efficiency about 1·5 times greater than the Taiwan-style paddle wheel aerators at salinities of 10–30 ppt (aeration efficiencies averaged 1·20 and 0·85 kg O 2 /kWh −1 , respectively). In the same salinity range, the second brand of propeller-aspirator-pump aerator had aeration efficiencies roughly equal to the Taiwan-style paddle wheel aerators.

Comparison of polyphosphate and orthophosphate as fertilizers for fish ponds.

Abstract Sodium polyphosphate and triple superphosphate were used as sources of polyphosphate and orthophosphate, respectively, at equal P 2 O 5 application rates in sunfish ( Lepomis spp.) ponds. Filtrable orthophosphate and total phosphorus concentrations were generally higher in ponds treated with polyphosphate. However, differences between chlorophyll a concentration and net sunfish production did not differ between treatments ( P > 0.05).