Vibrio spp. e suas implicações sobre larviculturas de camarões marinhos

Abstract

Microbiological analyses were carried out at a larviculture facility in Northeastern Brazil in order to identify the agent causing increased mortality in larvae and postlarvae of the shrimp species Litopenaeus vannamei. Six samples were collected and processed from the different steps of culture process such as: water from the larviculture tanks, zoea, shrimp nauplii, shrimp postlarvae, cysts of artemia and nauplii of artemia, and subsequently studied. The standard plate counts (SPC) of aerobic bacteria performed with the water from the tanks yielded mean values of 3,29 x 105 CFU/g. These values were lower than those obtained from the samples of postlarvae, zoea and nauplii of artemia (>106 CFU/g). The MPN for Vibrio in the water sample was 40/100 ml while that for the remaining samples exceeded 1,100/100g (zoea, shrimp postlarvae and nauplii of artemia). The cysts of artemia had MPN values for Vibrio under 10/100g. Batch Ia, containing disencapsulated cysts of artemia, yielded SPC values of 1.76 x 104 CFU/g, while batch Ib with chorion yielded an estimated <103 CFU/g. Similar figures were obtained for batch II, also with chorion. The following strains were isolated from the samples: V. alginolyticus, V. fluvialis and Vibrio spp. Susceptibility tests proved nalidixic acid and chloramphenicol to be the most effective antibiotics against this vibriosis.