Abstract
Aquaculture is a productive activity in economic growth due to market productivity which supports many Ecuadorian communities. However, exotic species has been the basis of this activity without considering the endemic and mega-diverse component of Ecuador. On the other hand, current aquaculture systems use a lot of water, generating discharge of nitrogen and phosphorus, causing a negative impact on natural watersheds. The present investigation focused on the diversification of aquaculture production and environmental care, through the polyculture of tilapia and river prawn, in a Biofloc system, which allows reducing the use of water, space, and food, taking advantage of all the nutrients of the aquatic environment without generating pollutant residues, from a carbon-nitrogen ratio of 20:1. The research project was developed under laboratory conditions at 2.728 amsl, for 8 weeks in pre-breading stages. Two factors were established in the study: type of culture (monoculture and polyculture) and production systems (traditional and biofloc), with three replicates. In the Biofloc system, the environmental variables such as temperature, pH, and oxygen did not show any significant differences between treatments (p≤0.05), while conductivity and total suspended solids increased during the test, and the nitrification processes stabilized at day 28 with values of 0.06±0.01 and 0.35±0.09 ppm in ammonium and nitrite respectively. The bacterial load was higher in the Biofloc system (113.66x103 CFU/ml) with predominance of Bacillus sp. and Pseudomonas sp. The bioflocs showed greater volume in polyculture (17.62 ml/L) and 26% of protein. Under these considerations, the best productive performance was detected in the Biofloc polyculture with a total productivity of 142.86g/m2 (p≤0.05). Therefore, diversification of species, types and culture systems are viable for aquaculture in Ecuador, generating an interaction between the chemical and biological components, allowing productive processes to be sustainable.
Highlights
Aquaculture practices in Ecuador have increased in the last decade and sustained by the production of white shrimp (Litopenaeus vannamei) and grey tilapia (Oreochromis niloticus)
As a product of a Biofloc system, are aggregates of algae, bacteria, protozoa and other organic matter, such as feces and unconsumed food; each flock remains attached to a matrix of mucus that is secreted by bacteria and bound by electrostatic attraction filamentous microorganisms to remain attached to the matrix (Hargreaves, 2013)
The present work evaluated an alternative in the intensive production of tilapia, under zero water exchange "Biofloc", incorporating a new aquaculture species such as river prawn (Macrobrachium sp.), which can be found wild in several rivers of the western Ecuadorian subtropics
Summary
Aquaculture practices in Ecuador have increased in the last decade and sustained by the production of white shrimp (Litopenaeus vannamei) and grey tilapia (Oreochromis niloticus). It should be noted that the aquaculture industry of Ecuador maintains crops with one species (monoculture), constant water change, low density and constant discharges of mineral nutrients to the surrounding watersheds This methodology generates inefficient production in established systems, increased use of antibiotics for disease control, and negative environmental impact on natural resources (Favre, 2015). The scarce diversification of species and aquaculture systems constitutes a risk to local producers as occurred in 1999 following the crisis of the white spot disease in the Ecuadorian shrimp sector (Calderón, 2002) In this sense, diversification is an important issue that reduces risks in production, which will allow the incorporation of new systems and methodologies for the aquaculture sector, diversify risks, generate new market opportunities and increase the productivity and competitiveness of the national supply. The present work evaluated an alternative in the intensive production of tilapia, under zero water exchange "Biofloc", incorporating a new aquaculture species such as river prawn (Macrobrachium sp.), which can be found wild in several rivers of the western Ecuadorian subtropics
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