Functional and productive performance of an integrated biosaline system with aquaculture effluent reuse in the Brazilian semi-arid region

Water scarcity and natural salinization constrain production in Brazil’s semi-arid region, underscoring the need for efficient water reuse strategies. This study evaluated the functional and productive responses of an integrated biosaline aquaculture–agriculture system that combines whiteleg shrimp (Penaeus vannamei) cultivation at different salinity levels with the reuse of aquaculture effluents for crop irrigation, to assess water reuse efficiency and identify limitations related to crop salinity tolerance. The experiment was conducted at the Federal Rural University of the Semi-Arid (UFERSA) in Mossoró, Rio Grande do Norte, Brazil, using a completely randomized design with four salinity levels (0, 5, 7.5, and 10 PSU) and three replicates. The integrated system comprised shrimp culture tanks coupled to agricultural beds irrigated exclusively with purge water from the aquaculture component. Shrimp zootechnical performance, effluent physicochemical quality, growth of banana (Musa spp.) and BRS Capiaçu grass (Cenchrus purpureus), and sustainability indicators such as water use efficiency (WUE) and protein efficiency of water use (PEW) were evaluated. Shrimp growth parameters did not differ among treatments (p > 0.05), whereas survival and productivity increased at higher salinity levels (p < 0.01). Effluent quality remained stable throughout the experiment. In the agricultural component, grass showed greater functional tolerance, whereas banana exhibited high sensitivity to salinity from 5 PSU onward. The system achieved 100% water reuse; however, WUE and PEW decreased with increasing salinity, indicating that system sustainability is primarily limited by the salinity tolerance of agricultural crops.