South-Americans freshwater crustaceans and the role as animal-mediated nutrient recyclers: application in integrated multitrophic aquaculture (IMTA).

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

Shanghái

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

Excretion is an immediate process by which animals mineralize nutrients for primary producers and heterotrophic microorganisms. Understanding the complementarity of cultured organisms is a way proposed by IMTA to deal with nutrient waste of intensive feeding. Crustaceans in IMTA could help to efficiently use feed, enhance water quality and increase profit. We determined the mass-specific nutrient mineralization (N, P, N:P) of crustaceans (prawn-Macrobrachium borellii, anomuran-Aegla uruguayana, crab-Trichodactylus borellianus) from South America fed with omnivorous and detritivorous fish-feed. We tested across, among and within-taxa the relationship of nutrient mineralization with body mass, body elemental content, and fish-feed to explore the animal-mediated nutrient dynamic and its role in productive systems as a group or individually. Across-taxa, juveniles excreted more N and P than adults, the N-body content positively affected the mineralization of N, and N:P body content negatively affected mineralized N:P. These relations were similar despite the type of feed. Among-taxa, prawns (more N-body content), mineralized more N, low P and N:P, in comparison with the other species. Within-taxa, juveniles of all species mineralized more N than adults and only juveniles of anomuran mineralized more P than adults. There was no relationship between nutrient mineralization and body content in any species. Crustaceans recycle differently N and P at different scales of analyses. Mineralization of omnivorous and detritivorous fish-feed were similar, but juveniles recycle more nutrients per mass unity than adults, mainly for N. Thus, at early stages, more N-compounds could be available to grow vegetables, and even more with prawns. Prawns incorporated more P and could limit this nutrient to primary producers. The role of crustaceans as animal-mediate nutrient recyclers depends mainly on the species and body mass and should be considered to select complementary species that efficiently use feed resources.