| Summary: | Juveniles (3.5 ± 0.3 g) of the white shrimp Litopenaeus vannamei were grown during 40 days with no water exchanges, no food addition and four initial densities (25, 50, 75 and 100 g m-3, corresponding to between 8 and 32 shrimp m-2), to determine growth rates, which could be achieved using the periphyton growing on artificial substrates as the only food source. The experimental culture units were 12 polyethylene 1 m³ cylindrical tanks with 4.8 m² of total submerged surface (bottom and walls), provided with 7.2 m² of artificial substrate (Aquamats™). There were no significant differences in the ammonia and nitrite concentrations determined in the four treatments (0.17-0.19 and 0.10-0.11 mg L-1, respectively), which remained below the respective levels of concern for shrimp cultures. Mean survival was similar, and ranged from close to 91 to 97%, whereas there were significant differences in mean individual weight, which ranged from 11.9-10.6 g shrimp-1 for the two low initial densities (25 y 50 g m-3), to 8.3-7.7 g shrimp-1 for the other treatments. However, because of the high survival and of the higher initial density, the best biomass yield was with 100 g m-3. The final nitrogen contents of sediment and water were lower than the initial values, and between 36 and 60% of the difference was converted into shrimp biomass.<br>Durante 40 días se cultivaron juveniles de camarón blanco Litopenaeus vannamei con un peso individual de 3,5 ± 0,3 g y biomasas iniciales de 25, 50, 75 y 100 g m-3 (equivalente a 8-32 ind m-2), sin cambios de agua y adición de alimento, para determinar la tasa de crecimiento usando como única fuente de alimentación el perifiton desarrollado en sustratos artificiales. Se utilizaron estanques cilíndricos de polietileno de 1 m³ con tres réplicas por tratamiento, con una superficie de 4,8 m² (paredes y fondo) y 7,1 m² de sustrato artificial (Aquamats™). No se encontraron diferencias significativas entre las concentraciones de amonio (0,17-0,19 mg L-1) y nitrito (0,10-0,11 mg L-1) determinadas en los cuatro tratamientos. La supervivencia fue similar, variando entre 91 y 97%. La ganancia en peso individual fue significativamente mayor en los tratamientos con menor biomasa inicial (25 y 50 g m-3), aunque por la mayor densidad inicial, el mejor rendimiento en biomasa se observó en los cultivos sembrados con 100 g m-3. Los contenidos de nitrógeno determinados al final del experimento, en el agua y sedimento, fueron inferiores a los valores iniciales, y entre el 36 y 60% de sus diferencias se recuperaron en biomasa de camarón.
|
|---|
