Author
 |
Ludwig, Gerald |
|
Submitted to: Book of Abstracts World Aquaculture Society
Publication Type: Abstract Only Publication Acceptance Date: 1/27/2002 Publication Date: 1/27/2002 Citation: LUDWIG, G.M. CONSTANT OR NOCTURNAL AERATION: EFFECTS ON WATER QUALITY AND ZOOPLANKTON STANDING CROPS IN HEAVILY FERTILIZED SUNSHINE BASS NURSURY PONDS. BOOK OF ABSTRACTS WORLD AQUACULTURE SOCIETY. 2002. p.191. Interpretive Summary: Technical Abstract: Rotifers, and crustacean zooplankton are required as initial foods by sunshine bass fry. Heavy fertilization increases zooplankton production but also causes poor water quality. This study was designed to determine the effect that aeration may have on zooplankton and water quality in heavily fertilized ponds that contained no fish. Four 0.04 ha ponds were aerated continuously, four only at night and four received no aeration. During 21 days after they were filled they received 1,224 kg/ha rice bran and 581 kg/ha liquid 9-27-0 NPK fertilizer. Water quality variables, chlorophyll a and zooplankton were sampled daily. Water temperatures were lower in the constantly aerated ponds than in unaerated ponds. Dissolved oxygen concentrations were the closest to optimum for fry during the morning and afternoon in constantly aerated ponds. Constant aeration also resulted in higher pH and concentrations of nitrite, nitrate, total ammonia, and un-ionized ammonia. Phosphate levels did not differ among treatments. Chlorophyll a concentrations were highest in constantly aerated ponds. Rotifers and crustacean zooplankton were highest during the time that fry would consume them in constantly aerated ponds. Ponds fertilized this heavily had pHs and unionized ammonia levels that were too high for sunshine bass fry. The high amounts of zooplankton produced by heavy fertilization and constant aeration are well suited for harvest for use in tank culture of fry. |
