José Antonio López Elías

Cultivos semicontinuos de cuatro especies demicroalgas con un medio no convencional

Four microalgae, Chaetoceros sp., Phaeodacrylrrm tticomutum Bohlin, Tetraselmis sp. and Pavlova futheti (Droop) Hibberd, were kept in semicontinuous cultures at dilution rates between 75 and 15%, depending on species and medium. The quantity and quality of the biomass produced using a nonconventional culture medium were compared to that obtained with a traditional formulation. The biomass produced did not differ qualitatively as a result of medium or dilution rates, but the daily yield of Tetraselmis sp. and of Pavlova Iuthen’ was significantly lower with the nonconventional medium. The best yields of Chaetoceros, Phaeodactylum, Tetraselmis and Pavlova were with dilution rates of 50, 60 and 40% for the conventional medium and 25, 70, 40 and 30% for the nonconventional formulation. The savings, in terms of cost of chemicals, range between 91 and 70%, depending on the grade of the chemicals and on the species in culture.

Efecto del fotoperiodo y la razon camaron:macroalga en la remoción de nitrogeno amoniacal total por Gracilaria vermiculophylla, en cultivo con Litopenaeus vannamei, sin recambio de agua

A study was conducted to evaluate the effect of the photoperiod and biomass rate of shrimp:macroalgae over the total ammonia nitrogen (TAN) removal by the macroalgae Gracilaria vermiculophylla, in an integrated culture with shrimp Litopenaeus vannamei, with zero water exchange. Four photoperiods were evaluated: 12:12, 14:10, 16:08 and 24:00 h of light:darkness and two biomass ratios 1:4 and 1:8. The experimental design was a factorial of 4x2, with four replicates by treatment. The lowest concentrations TAN (0.55 ± 0.17 mg L -1 ), N-NO2 (0.145 ± 0.29 mg L -1 ) y N-NO3 (3.13 ± 0.73 mg L -1 ) were registered in the biomass rate of 1:8. The highest growth rates of the macroalgae (3.07 ± 1.44% day -1 ) were recorded with 24:00 h photoperiod and biomass ratio 1:8. The highest rate of N incorporation (0.31 ± 0.12 mg N L -1 ) of the macroalgae occurred under the same conditions. Shrimp growth was similar to data reported in traditional recirculation systems. The integration of G. vermiculophylla without water exchange system was able to maintain the TAN and N-NO2 under levels conditions for the growth of L. vannamei.

Survival of Litopenaeus vannamei shrimp fed on diets supplemented with Dunaliella sp. is improved after challenges by Vibrio parahaemolyticus

Survival of Litopenaeus vannamei was evaluated during a Vibrio parahaemolyticus infection. This bacteria has been causing significant economic losses in the shrimp industry due to the appearance of early mortality syndrome (EMS), also known as acute hepatopancreatic necrosis disease (AHPND). Control of bacteria in ponds is difficult to achieve with antibiotics due to environmental infections and antibiotic resistance. New methods have been proposed to control and prevent the impact of bacterial infections. The physiological response indicated by plasma biochemical parameters in shrimp can determine their health and stress status. Meanwhile, shrimp immunology is the key factor in establishing strategies to control diseases. Immunostimulants are the best alternative to antibiotics to prevent or minimize disease damage, and at the same time, these stimulants improve the immune system in shrimp. Four diets containing 1.5, 2, 2.5 and 3% of Dunaliella sp. with high β-carotene content were tested in the present study. After 20days of feeding, organisms were infected with V. parahaemolyticus. Protein, glucose, lactate, triglyceride and cholesterol levels, as well as activity of prophenoloxidase and phenoloxidase, were determined 48 h post-infection (hpi). Shrimp fed a diet with 3% Dunaliella sp. showed the highest survival. Glucose, cholesterol, and triglyceride levels, as well as prophenoloxidase and phenoloxidase activity, were not observed to be suitable indicators during this bacterial infection. The results indicated that the inclusion of Dunaliella sp. in diet increases survival in L. vannamei infected with V. parahaemolyticus.