Mapará and Amazon River prawn farming in multispace and multitrophic systems

Abstract

Sustainable systems for the production of mapará, Hypophtalmus spp, and Amazon River prawn, Macrobrachium amazonicum, will be studied trough an ecosystem approach, as well as, innovative and novel methods will be developed and tested for assessment of the sustainability in aquaculture. We intend to investigate essential processes for the establishment of bio manipulation and evaluation of environmental sustainability in cultures, such as, the efficiency in the incorporation of nutrients, energy and mass balances, effluent eutrophying and greenhouse gases emission. In subproject I, the possibility of domestication, the cycle and reproductive performance of mapará reared in captive and in intercropping system with prawns in Amazonia will be assessed. For that, eight 80m² ponds will receive 800 amazon river prawn breeders (10/m2) that will occupy the bottom; and 160 mapará breeders (1/4 m2) that will occupy the water column. The following water parameters will be regularly recorded: temperature, transparency, conductivity, pH, dissolved oxygen and ammonia. The reproductive cycle of mapará will be determined by sampling every two months, where, 4 females and 4 males will be captured for blood sampling, ovaries and testes samplings, respectivelly, but also to record biometric data. It will be considered the gonado-somatic index (GSI), the condition factor K, morphometric characteristics of gonads and gonadal steroid levels. The reproductive performance of mapará will be assessed by inducing spawning with pituitary extract and GnRH. The prawn breeders will be evaluated every two months. At each prawns sampling populations (50 animals) in six ponds will be collected for reproductive cycle study. The animals will be measured and weighed, diagnosed according to sex and types. Females will be classified for the presence of eggs on the pleopods, the degree of ovarian maturation and eggs embryonic development. At the end of 18 months, ponds will be exhausted and all survivors will be counted and analyzed according to the criteria above. In subproject II the reproductive biology of mapará in natural environment will be assessed. For this, the animals will be collected every two months on the Tocantins River for a period of 24 months. At the time of collection, the following parameters will be measured: water temperature, transparency, conductivity, pH, dissolved oxygen and ammonia. The procedures to determine the reproductive cycle of animals will be exactly the same as described for the sub-project I. At the end of the analysis, the data obtained in captivity will be compared with those obtained in a natural environment for evaluation of the physiological adaptations of the species in captivity, and its possible impacts on their reproductive performance. In the subproject III, the productivity, cost and sustainability of multitrophic and multispace production systems, involving the production of the amazon river prawn and mapará will be evaluated. 12 rectangular ponds with 0.01 ha and average depth of 1 m will be used. The experiment will be completely randomized with four treatments (combination of species) and three replications. The treatments will include: stocking 30 prawns/m2; 30 prawns /m2 + 0,5 maparás/m2; 30 prawns/ m2 + 1 mapará/m2 and 1mapará/2. Samples of pond water and effluent will be collected to determine the hydrological and limnological variables of interest for aquaculture and sustainability. The greenhouse gases will be measured in all experimental units. After the harvest for each treatment, the mass and energy production will be determined for each system, as well as the morphological response of animals to treatments. Also, the production costs, economic viability, and economic, social and environmental indicators will be determined. The carbon, nitrogen and phosphorus balance and energy in systems will also be determined to provide input for the practice of biomanipulation. (AU)