The stable isotope of nitrogen in an experimental culture of Ulva spp. and its assimilation in the nutrition of white shrimp Litopenaeus vannamei, Baja California Sur, Mexico

Stable nitrogen isotope ratios have been used to study the incorporation of nitrogen into the food webs of marine systems. Some species of algae can be cocultured with shrimp, resulting in a sustainable alternative to reduce or eliminate the use of commercial food. One option is the development of Ulva spp. in open-air ponds under a rigor- ous control of water quality. Recently, the coculture of Ulva spp. and juvenile shrimp (in aquaria and open-air ponds) has shown, under stereomicroscope observation, that the crusta- ceans were feeding on the Ulva spp. The consumption of commercial food and Ulva spp. by juvenile shrimp has been evaluated to establish the uptake of nitrogen into tissues of this crustacean. The muscle tissue of juvenile shrimp initial- ly assimilated nitrogen from commercial feed and later the cocultured shrimp assimilated nitrogen from the Ulva spp., which demonstrated the potential application of live and fresh diets and the optimization of their use in diets contain- ing very low levels or no commercial food.