Efeito de duas estratégias de fertilização sobre a composição do fitoplâncton no cultivo de Litopenaeus vannamei

Abstract

Phytoplankton development in shrimp ponds was analyzed using two different fertilization strategies. Treatments designed were: (T1) sodium nitrate enriched with phosphate, silicate, boron, magnesium, sulfur and, potassium; (T2) urea, triple superphosphate and sodium silicate. Phytoplankton was collected weekly and species were classifi ed in four main groups: Diatoms, Cyanobacteria, Chlorophyceae and Dinofl agellate. Mean Diatoms density was signifi cantly higher in T1 (12,554 cells./mL) compare to T2 (5,833 cells./mL). Cyanobacteria (T1 = 150,567 and T2= 161,729 cell/ mL), Chlrophyceae (T1 = 15,642 and T2 = 13,534 cell/mL) and Dinofl agellate (T1 = 438 and T2 = 451 cell/mL) mean densities were similar in both treatments. Results indicated that T1 is more effi cient for Diatoms reproduction. However, undesirable microalgae densities were superior than the desirable ones. Therefore, further studies are necessary to improve the fertilization management for better results in shrimp ponds