Alternative sources of water in the cultivation of Litopenaeus vannamei (Boone 1931) in a biofloc system
The cultivation of marine shrimp depends on the use of salt water, therefore, to make their development feasible away from the coast, strategies are needed to reduce the salinity and the amount of salt water used. Salt water for crops far from the coastal area can be obtained by transporting marine water, using brackish groundwater or by artificial salinization. The reduction of its use is possible through superintensive and closed cultivation systems such as the bioflocations system (BFT), when it is possible to reuse water in several cultivation cycles and thus reduce the amount of salt water and saline effluents.This work aimed to provide information that allows the interior production of Litopenaeus vannamei through the understanding of the appropriate ionic composition of water and its modifications. To this end, four experiments were carried out at the aquaculture marine station of the Federal University of Rio Grande (EMA-IO-FURG): 1. Ionic composition of water over a cultivation cycle of Litopenaeus vannamei (Bonne, 1931) in BFT; 2. Performance of L. vannamei post larvae reared in indoor nursery tanks under BFT conditions at different salinities and zero-water exchange; 3. Alternative sources of water for the cultivation of Pacific white shrimp in BFT; 4. Cultivation of L. vannamei in BFT at low salinity: Replacement of sea water with sodium chloride and different concentrations of magnesium.In chapter 1, the change in salinity and ionic composition of the water over 63 days of cultivation was verified without significant change in the performance of the shrimp. In chapter 2, a minimum salinity of 8g / L was observed to ensure the survival and weight gain of larvae of L. vannamei. Chapter 3, on the other hand, proved the possibility of growing shrimp with different sources of water, whether they are artificially saline or naturally brackish. Naturally brackish water and sea water promoted the development, especially of diatom microalgae, whereas in artificially saline water these algae did not contribute satisfactorily to the cultivation. In chapter 4, the feasibility of replacing up to 50% of marine water with sodium chloride was verified, without prejudice to the survival and growth of L. vannamei.However, this substitution was not suitable for artificially saline water. The different levels of magnesium tested (50, 100 and 200%) did not result in differences in weight gain, only an increase in survival in the highest tested content. The results obtained subsidize and stimulate the development of marine shrimp inland crops in BFT systems.