MODIFICAÇí-ES NA COMPOSIÇÃO IÔNICA DA ÁGUA EM VIVEIROS ABASTECIDOS POR POí­"¡OS SALINIZADOS

Resumo

The "Well-Fish" Project utilizes in the fish breeding, saline wells localized at Alto-Pajeú Northeastern region in order to make good use of the scarce "water" resource for production of animal protein at low cost, as well to promote the fish breeding activities at Semi-Arid region. Previously, two communities were selected, and on each one, beside an artesian well, it was raised a module with two fish ponds of 1000 m² each. The stocking density was 1.3 fish/m², 50% Oreochromis niloticus and 50% Prochilodus cearensis. During the cultivation time (from February to December 1995) observation were made in order to characterize probable modifications occurred in the ionic composition of the water, as well others correlated variables. The water ionic composition was strongly influenced by climatic and geochemical conditions, and, on this way, different characteristics were recorded during rainy and drought periods. In the rainy period, the water ionic concentration varied from 11.460 to 25.922 meq./L and the predominant ions were: Na⁺, Mg⁺⁺, Ca⁺⁺, Cl^- and HCO₃^-. In the drought period the salt concentration was greater, varying from 35.826 to 55.794 meq./L, prevailing the ions Mg⁺⁺ e Cl^-.