Characterization of water quality during freshwater culture of shrimp Litopenaeus vannamei in southern Ecuador
2023
Patricio Colón Velásquez López | Juana Fulvia Solorzano Reyes | Patricia Migdalia Ochoa Pereira | Galo Wilfrido Solano Motoche | Patricio Quizhpe Cordero | Roy Manuel Guillen Añasco
The present work characterizes the water quality during the culture of shrimp Litopenaeus vannamei in an open system, using fresh well water (0.3 ‰ salinity). The water extracted from the subsoil contained 0.3 ‰ salinity, 0.0115 mg L-1 phosphate (P-PO4), 0.003 mg L-1 nitrite (N-NO2), 0.029 mg L-1 nitrate (N-NO3), < 0.010 mg L-1 ammonium N-NH4, 300 mg L-1 total hardness and 210 mg L-1 alkalinity. The study includes the analysis of the acclimation process of 20-day-old L. vannamei post-larvae and its further development in an open culture system. During acclimation, ammonium concentration increased from non-detect to 1.2 mg L-1 on the second day, and then to 1.5 mg L-1 on the eighth day. Survival of post-larvae upon reaching the freshwater point was 51 %. During 8 weeks of culture in the 2 earthen ponds, the nutrient concentration fluctuated between 0.01 - 0.03 mg L-1 for nitrite, 0.02 - 0.03 for nitrate, 0.07 - 0.09 for ammonium and 0.19 - 0.21 mg L-1 for phosphate. The most representative phytoplankton groups were chlorophyte, diatoms, dinoflagellates and euglenoids, with about 50.6, 25, 14 and 9.2 %, respectively in average for both ponds. The cyanophyte group was represented in the 1% of the phytoplankton community. Spirogyra sp. was the most dominant species. The total heterotrophic bacteria concentration was around 1100 CFU mL-1, while Vibrio sp., Pseudomonas sp. and total coliforms reached an average concentration of 47, 72 CFU mL-1, and 59 CFU/mL-1 respectively. The average weekly growth of L. vannamei was 0.9 g, survival was 45.9 %, and production was around 1088 kg/ha. The nature of the well water in southern Ecuador provides the necessary nutrients for the cultivation of L. vannamei shrimp at extremely low salinity.
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