WWW.WAS.ORG • WORLD AQUACULTURE • DECEMBER 2017 41 Universidade Federal Rural de Pernambuco at Recife, Brazil. The system consisted of 12 blackplastic tanks (the useful dimensions of the tanks were 50 × 35 × 23 cm, equivalent to 40 L). Five days prior to stocking shrimp and seaweed, tanks were filled with water from a matrix tank (alkalinity 134 mg CaCO3/L, total suspended solids 103-134 mg/L, and dissolved inorganic nitrogen < 3 mg/L) to approximately 25 percent of the volume and the remaining volume was filled with seawater. No water exchange was carried out during the experimental period, except for the addition of dechlorinated fresh water to compensate for losses from evaporation. Aeration was provided to maintain the dissolved oxygen concentration at 4 mg/L. Hydrated lime was used to maintain alkalinity above 100 mg/L and pH above 7.5. Shrimp were obtained from a commercial farm and tested for the presence of WSSV infection. In the first trial, 2.6 g shrimp were stocked into experimental units at 425/m3. In the second trial, 0.3 g shrimp were stocked at 500/m3. Shrimp were fed daily with a 40 percent crude protein commercial shrimp feed, adjusted daily according to the estimated shrimp consumption, mortality rate and leftover feed. Molasses was added once daily as a carbon source to maintain a carbon to nitrogen ratio of 12. In the first trial, two seaweed species (G. birdiae and G. domingensis) were used and experimental units were stocked with Aquaculture production can increase waste discharge and effluent nutrients concentration, generating environmental and social challenges (Troell et al. 2009). In biofloc systems, 65 percent of the phosphorus and 61 percent of the nitrogen in feed are not recovered in shrimp biomass (Silva et al. 2013). Intensive systems with zero or minimal water exchange produce large amounts of sludge (11.315.1 kg/m2) (Coyle et al. 2011), biochemical oxygen demand (31-48 mg/L) and chemical oxygen demand (321-478 mg/L) (Mishra et al. 2008), total suspended solids (403-800 mg/L) and volatile suspended solids (215-450 mg/L) (Vinatea et al. 2010). An appropriate combination of fish or shrimp with bioremediating organisms is necessary for environmental and economic balance to occur. Integrated multi-trophic systems represent a strategy to minimize waste of nitrogen and phosphorus, reduce the possibility of disease outbreaks, and reduce environmental problems (Ren et al. 2012, Lander et al. 2013). The selection of species in a multitrophic system should consider the functions that each organism plays in the ecosystem and its economic potential. This article describes the results of two trials to assess shrimp performance in an integrated multitrophic biofloc system (IMTBS) with Pacific white shrimp Litopenaeus vannamei and the red seaweeds Gracilaria birdiae and Gracilaria domingensis (Fig. 1). Trials were conducted at the Sustainable Mariculture Laboratory, Departamento de Pesca e Aquicultura of the Performance of Pacific White Shrimp Reared in an Integrated Multitrophic Biofloc System with Gracilaria Seaweed Luis Otavio Brito, Jéssika Lima de Abreu, Clarissa Vilela Figueiredo da Silva Campos, Danielli Matias de Macedo Dantas, Elizabeth Pereira da Silva and Alfredo Olivera Galvez (CONTINUED ON PAGE 42) FIGURE 1. The red seaweeds Gracilaria birdiae (A) and Gracilaria domingensis (B) used in an integrated multi-trophic biofloc system (C). G.birdiae (D) and G. domingensis (E) at the end of shrimp culture trials in an integrated multi-trophic biofloc system. This article describes the results of two trials to assess shrimp performance in an integrated multitrophic biofloc system (IMTBS) with the red seaweeds Gracilaria birdiae and Gracilaria domingensis. The presence of seaweed improved shrimp growth. The use of seaweed with shrimp may be a complementary source of food through direct consumption or grazing of the biofilm that forms on the surface of the seaweed. Additionally, seaweed in IMTBS can combine bioremediation capacity with commercial value as human food.
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