Among and within-taxa variations of body elemental content of South-American freshwater crustaceans: assessing trophic status and application in integrated multi-trophic aquaculture.

DE AZEVEDO CARVALHO, DEBORA; MUSIN, GABRIELA; TORRES, MARÍA VICTORIA

Shanghái

Congreso; Global Conference on Aquaculture Millennium +20 Aquaculture for food and sustainable development; 2021

The body elemental composition is a useful baseline to establish the nutritional requirements of animals and are related with growth and natural trophic status. Carbon-C, nitrogen-N and phosphorus-P are key elements required for growth, homeostasis of organisms and, therefore, to aquaculture productivity. We measured the body elemental content (C, N, P) of juveniles and adults of three freshwater crustaceans native to South America (prawn-Macrobrachium borellii, anomuran-Aegla uruguayana, crab-Trichodactylus borellianus), infer their nutritional needs and the application in integrated multitrophic aquaculture (IMTA). Specimens were captured in the wild, transferred to laboratory, kept in starvation during 24-hours, sacrificed, dried and elemental analyzed. The body content of elements and ratios C, N, P, N:P, C:N, C:P were compared among-taxa through ANCOVA and using body mass (an ontogenetic parameter) as covariate. Body elements and ratios were also analyzed within-taxa as a function of body mass. Among-taxa, species showed significant differences in all elements and ratios and a significant effect of body mass on N, P and C:N. Prawns had more C, N and N:P, and less C:N than anomurans and crabs. Anomurans had less P and intermediate N, C, N:P and C:N. Crabs had higher P and lower C:P and N:P than anomurans and prawns. Within-taxa, only crabs exhibited less body-N as they grow. Prawns and crabs exhibited a positive relationship between body-C:N and body mass. Results showed higher N-requirements and higher trophic status (lower C:N) of prawns than anomurans and crabs. Moreover, prawns and crabs change the trophic status during ontogeny, requiring lower N in comparison with C at later stages. Prawns need more protein in the feed and might be successfully integrated with fish of higher N-requirements, while crabs and anomurans might exhibit good performance with herbivorous and omnivorous fish.