The implication of metabolically active Vibrio spp. in the digestive tract of Litopenaeus vannamei for its post-larval development.

This work aimed to evaluate the link between the occurrence/abundance of Vibrio populations and bacterial composition in shrimp's intestine (Litopenaeus vannamei) during post-larval ontogenetic development and in its culture water, and the correlation of these with environmental parameters. The total and metabolically active populations of Vibrio in the digestive tract of shrimp during its post-larval development were analysed using quantitative PCR (qPCR) and reverse transcription qPCR targeting the 16S rRNA gene sequence. A lab-scale shrimp bioassay was performed for 80 days in a recirculating aquarium under strictly controlled conditions. The results indicate that the Vibrio population from shrimp's gut is associated with its developmental stage and the environment. Multivariate analyses revealed that the presence of Vibrio spp. drove the studied system, but their metabolically active performance was related to earlier developmental stages in an aqueous environment. Also, the samples taken from water of culture units to compare the influence of the aquatic environment on the intestinal microbial community during shrimp's ontogenetic development showed significant differences. Finally, our results revealed that Vibrio is an important member of shrimp's gut microbiota; however, its metabolic activity seems to be highly regulated, possibly by the host and by the rest of the microbiota.

Evaluation of the productive and physiological responses of Litopenaeus vannamei infected with WSSV and fed diets enriched with Dunaliella sp.

An experimental investigation was performed to evaluate the productive and physiological responses of Litopenaeus vannamei that were infected with WSSV and fed diets enriched with Dunaliella sp., which had a high ß-carotene content induced by nitrogen reduction in the culture medium. A basal diet containing 35% crude protein and experimental diets T1 and T2, which included 1% and 2% microalgae meal, respectively, were evaluated. Positive (infected juveniles) and negative (non-infected) controls were also evaluated. Survival was significantly higher (80%) in the two treatment groups compared to the positive control group (56%). In the negative control group, survival was 100%. Some variation was recorded for hemolymph metabolites among treatments and at distinct times post-infection; although the tendencies were not clear, some metabolites (glucose and triglycerides) appeared to decrease on the last days of the trial, probably due to their use as energy for the shrimp to thrive despite the infection. The results of the study suggest a positive effect of the dietary inclusion of Dunaliella meal on shrimp survival and an unclear effect on hemolymph metabolites.

Effluents of shrimp farms and its influence on the coastal ecosystems of Bahía de Kino, Mexico.

The impact on coastal ecosystems of suspended solids, organic matter, and bacteria in shrimp farm effluents is presented. Sites around Bahía de Kino were selected for comparative evaluation. Effluent entering Bahia Kino (1) enters Laguna La Cruz (2). A control site (3) was outside the influence of effluents. Water quality samples were collected every two weeks during the shrimp culture period. Our data show that the material load in shrimp farm effluents changes biogeochemical processes and aquatic health of the coastal ecosystem. Specifically, the suspended solids, particulate organic matter, chlorophyll a, viable heterotrophic bacteria, and Vibrio-like bacteria in the bay and lagoon were two- to three-fold higher than the control site. This can be mitigated by improvements in the management of aquaculture systems.