27 research outputs found
Effect of photoperiod stress assessment and locomotor activity of female lambari (Astyanax bimaculatu)
Epizootiology of Perkinsus sp. inCrassostrea gasar oysters in polyculture with shrimps in northeastern Brazil
Evaluation of Autotrophic and Heterotrophic Microcosm-based Systems on the Production Response of Litopenaeus vannamei Intensively Nursed without Artemia and with Zero Water Exchange
An experiment was conducted for 28 days to evaluate the productive response of the Pacific white shrimp (Litopenaeus vannamei) postlarvae, intensively nursed in autotrophic or heterotrophic microcosm-based treatments, without Artemia and zero water exchange. The autotrophic system was based on the promotion of microalgae as the main primary producers. The heterotrophic system was based on the promotion of bacteria as the main primary producers. The control was fed a conventional diet. Bioflocs and biofilms were used to promote biota in the autotrophic and heterotrophic systems. There were no differences in temperature, salinity, or DO among treatments. The chlorophyll a concentration and microalgae density were much greater in the control and autotrophic system than in the heterotrophic. The concentration of heterotrophic bacteria was significantly higher in the heterotrophic than in the autotrophic system and control. Individual weight gain was higher in the control (81±2 mg) and heterotrophic (77±8 mg) treatments than in the autotrophic (58±10 mg) but survival was better in the autotrophic (86%) than control (77%) and heterotrophic (76%) treatments. Final biomass was statistically similar in all treatments, as well as the feed conversion ratio which ranged from 0.65 (heterotrophic) to 0.69 (autotrophic). The increased natural productivity caused a positive productive response in the shrimp postlarvae. Such strategies can be an adequate alternative when Artemia is unavailable
Effect of supplying four copepod densities (Acartia sp. and Calanus pacificus) onthe productive response of Litopenaeus vannamei pregrown intensively at microcosm level
A seven-week experiment was performed to evaluate the effect of supplying copepods (Acartia sp. and Calanus pacificus), as exogenous feed during the intensive pre-growout phase of white shrimp (Litopenaeus vannamei), on the productive parameters and water quality. Five treatments were tested in which shrimp were fed formulated feed and the addition of 0 (control), 1, 2, 4, or 8 copepods mLâ1. Treatments with 1 and 4 copepods mLâ1 had higher ammonia nitrogen levels than the rest of the treatments (>4 mg Lâ1). Nitrite levels were significantly higher in the treatment with 8 copepods mLâ1, whereas nitrate levels were higher in all treatments relative to the control. Phosphate concentration was higher in the treatments with 4 and 8 copepods mLâ1. Shrimp from the treatments with 2, 4, and 8 copepods mLâ1 showed a higher survival (>93%), weight (>3.1 g), and final biomass (>77 g). The treatment with 2 copepods mLâ1 had the best feed conversion ratio (1.19) compared with the rest (>1.7). The results suggest that the additional supply of copepods as exogenous feed during the intensive pre-growout phase of shrimp culture can have a negative effect on the water quality, although survival was not affected; however, the effect on the production parameters was positive, indicating that the use of copepods as exogenous live feed is feasible in the culture of white shrimp.
LoÌpez-ElıÌas, âEvaluation of autotrophic and heterotrophic microcosm-based systems on the production response of Litopenaeus vannamei intensively nursed without Artemia and with zero water exchange,â Israeli
Abstract An experiment was conducted for 28 days to evaluate the productive response of the Pacific white shrimp (Litopenaeus vannamei) postlarvae, intensively nursed in autotrophic or heterotrophic microcosm-based treatments, without Artemia and zero water exchange. The autotrophic system was based on the promotion of microalgae as the main primary producers. The heterotrophic system was based on the promotion of bacteria as the main primary producers. The control was fed a conventional diet. Bioflocs and biofilms were used to promote biota in the autotrophic and heterotrophic systems. There were no differences in temperature, salinity, or DO among treatments. The chlorophyll a concentration and microalgae density were much greater in the control and autotrophic system than in the heterotrophic. The concentration of heterotrophic bacteria was significantly higher in the heterotrophic than in the autotrophic system and control. Individual weight gain was higher in the control (81±2 mg) and heterotrophic (77±8 mg) treatments than in the autotrophic (58±10 mg) but survival was better in the autotrophic (86%) than control (77%) and heterotrophic (76%) treatments. Final biomass was statistically similar in all treatments, as well as the feed conversion ratio which ranged from 0.65 (heterotrophic) to 0.69 (autotrophic). The increased natural productivity caused a positive productive response in the shrimp postlarvae. Such strategies can be an adequate alternative when Artemia is unavailable