Aquamimicry System: Technological alternative for intensive cultivation of marine shrimp Litopenaeus vannamei. A comparison with the Biofloc system (BFT)
The shrimp Litopenaeus vannamei is the species of crustacean with higher production and greater economic value mainly due to its productivity and profitability. However, the traditional system of cultivation of these organisms, using ponds excavated in the coastal zone, can generate impacts to the environment mainly due to the discharge of effluents, which can cause eutrophication of the adjacent coastal region and affecting marine habitat. In addition, the high renewal and instability of the quality of cultivated water make organisms more susceptible to pathologies. In order to minimize these serious problems, technologies have been developed that aim to reduce the impact of aquaculture production while acting to improve the zootechnical performance of animals. Among these technologies are the BFT system (biofloc technology) and more recently the “Aquamimicry” or aquamimetic technology. The BFT system consists of maintaining a specific proportion between carbon and nitrogen, favoring the growth of heterotrophic bacteria which consume organic nitrogen, improving water quality and serving as a complementary food source for shrimp. The Aquamimicry system, similarly, deals with the insertion of a carbon source in the cultivation environment without a specific relationship between carbon and nitrogen, providing a food called “symbiotic”, that is, with a prebiotic source usually consisting of an oligosaccharide from the fermentation of bran, such as rice or soy and another probiotic, such as, for example, strains of Bacillus sp., thus conferring better performance of the animal mainly in relation to the immune response. Thus, the objective of this work was to carry out a comparative analysis between the technologies mentioned above, through the parameters of water quality, zootechnical performance and the microorganisms present in the cultivation environment. For this experiment, six ponds (600 m2 each) were used, covered with HDPE blankets. Two treatments were proposed with three repetitions each, one of them called Biofloc Treatment (TBio) using organic fertilization using sugar molasses and the second treatment called Aquamimicry system (TMi) in which fertilized with rice bran and commercial strains of. Bacillus sp. After the end of the experimental period (120 days), the data were analyzed and compared, in relation to the two technologies of cultivation of the white shrimp Litopenaeus vannamei. With average temperatures of 24 °C, dissolved oxygen levels around 8.0 mg/L, average pH with little variation (8.40) and alkalinity remaining in the range of 240 mg/L. The results obtained from the physical-chemical parameters showed us that both treatments were able to maintain the good quality of the culture water. The nutrients analyzed, in the same way as the physical-chemical parameters, remained at acceptable levels, with the average values of ammonia, nitrite, nitrate and phosphate found being 0.25 mg/L, 0.30 mg/L, 1.52 mg/L and 0.10 mg/L, respectively. The microbial communities present in the systems differed with respect to abundance, with the phytoplantonic group being represented by chlorophytes, diatoms and cyanobacteria, more abundant in the BFT system whereas, in the Aquamimicry treatment, there was a greater abundance in the group of zooplankton represented by ciliates, flagellates and rotifers. With regard to the zootechnical performance of the animals, there was a similarity between the averages of treatments with final weights reaching values around 11.0 g, average survival of 50 % and productivity between 3.0 and 4.0 ton/ha. According to the data analyzed, we can infer that both treatments were efficient in the production of marine shrimp in an intensive system with coated ponds, even with some differences in the results found between the BFT and Aquamimicry treatments.