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A single farmed fish species assimilates about 20% of the nutrients in the supplied diet. This study evaluated if the culture of complementary ecological-function species can recover nutrients dispersed into water and transform them into high-valued biomass. A completely randomized experiment was designed with three treatments and four replications of each production system: monoculture of lambari (Astyanax lacustris); integrated aquaculture of lambari and Amazon river prawn (Macrobrachium amazonicum); and integrated aquaculture of lambari, Amazon river prawn, and curimbatá (Prochilodus lineatus). Fingerlings of lambari (0.8 ± 0.8 g) were stocked in twelve earthen-ponds (0.015 ha) at the density of 50 fish m−2. Eight ponds were stocked with juveniles of Amazon river prawn (1.1 ± 0.2 g) at the density of 25 prawn m−2. Four of these eight ponds were stocked with curimbatá fingerlings (0.2 ± 0.1 g) at a density of 13 fish m−2. Only lambari was fed twice a day with an extruded commercial diet. The experiment lasted 60 days when lambari attained commercial size. The inclusion of prawn increased the total species yield from 1.8 to 2.4 t ha−1 cycle−1 and reduced the feed conversion ratio (FCR) from 2.5 to 1.8. The inclusion of prawn and curimbatá increased the total yield to 3.2 t ha−1 cycle−1 and reduced the FCR to 1.4. Therefore, the integrated culture of lambari, prawn, and curimbatá improves the use of space, water, feed, and benthic species to recover the large quantity of nutrients accumulated in the bottom of lambari pond production, converting them into high-nutritional and monetary-valued biomass.

Water, sediment and associated fauna were studied in a water hyacinth (Eichhornia crassipes) stand of a constructed wetland, used for aquaculture effluent treatment in SE Brazil, in February-April (summer/rainy season) and July-September (winter/dry season). The hydrological regime and decomposition processes had strong impact on the wetland water quality and on the associated fauna composition. Protozoa and Rotifera were at high densities, mainly in the dry season. Vorticella sp. was the dominant species in both seasons. Zooplankton richness, evenness and diversity were high during both seasons, with higher levels during the rainy season. Protozoa diversity and evenness were higher in the dry season when the water volume was lower. Maximum plant residence time in this wetland should be about 60 days.RESUMEN: Fauna asociada a Eichhornia crassipes en un humedal artificial para tratamiento de efluentes de acuacultura.Agua, sedimento y fauna asociada fueron muestreados entre las Eichhornia crassipes de un humedal artificial en el SE de Brasil usado para tratar efluentes de acuacultura, durante febrero-abril (verano/estación lluviosa) y julio-septiembre (invierno/estación seca). El régimen hidrológico y los procesos de descomposición tuvieron un fuerte impacto sobre la calidad de agua dentro del humedal y sobre la composición de la fauna asociada. Protozoa y Rotífera presentaron alta densidad, especialmente durante la estación seca. Vorticella sp. fue la única especie dominante en ambas estaciones. En ambos períodos la riqueza, uniformidad y diversidad del zooplancton fueron altas, siendo mayores en la estación lluviosa. La diversidad y uniformidad de Protozoa fueron mayores en la estación seca, cuando el volumen de agua era menor. El tiempo máximo de residencia de las plantas debería ser de unos 60 días.REZUMAT: Fauna asociată speciei Eichhornia crassipes într-o zonă umedă artificială pentru tratarea efluenților din acvacultură.S-au analizat apa, sedimentul și fauna asociată dintr-o parcelă de Eichhornia crassipes dintr-o zonă umedă construită pentru tratarea efluenților din acvacultură în SE Braziliei, în perioadele februarie-aprilie (vară/sezon ploios) și iulie-septembrie (iarnă/sezon secetos). Regimul hidrologic și procesele de descompunere au avut un impact puternic asupra calității apei din zona umedă precum și asupra compoziției faunistice asociate. Protozoarele și rotiferele au prezentat densități mari, în special pe timpul sezonului secetos. Vorticella sp. a fost singura specie dominantă din ambele sezoane. Abundența, distribuția și diversitatea zooplanctonului au fost mari în ambele sezoane, dar cu valori superioare în sezonul ploilor. Diversitatea protozoarelor și distribuția lor au fost mai ridicate în sezonul secetos, când volumul de apă a fost mai scăzut. Timpul maxim de ședere al plantelor în această zonă umedă ar trebui să fie de circa 60 zile.

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The fish Hyphessobrycon eques and Piaractus mesopotamicus, the snail Pomacea canaliculata, the aquatic plant Lemna minor and the microcustacean Daphnia magna were selected to evaluate the lethal or effective concentration (LC50/EC50) and the environmental risk of florfenicol (FLO), enrofloxacine (ENR), thiamethoxan (TH) and toltrazuril (TOL). For this, the organisms were acclimated in a bioassay room under controlled temperature and photoperiod, and then exposed to increasing drugs concentrations according to specific standard for each organism. L. minor is the sole organism which showed toxicity to FLO LC50; 48 h of 97.03 mg/L, which causes medium environmental risk. P. canaliculata was more sensible to ENR (14.64 mg/L), which causes high risk to the bioindicators. P. mesopotamicus was more sensible to TH toxicity (16.97 mg/L), which causes high risk also; followed by H. eques. TOL causes medium risk and it is more toxic for P. mesopotamicus (3.72 mg/L), followed by H. eques. L. minor can be used as a bioindicator for florfenicol toxicity, P. canaliculata for enrofloxacine and H. eques for TH and TOL, emphasizing that enrofloxacine and thiamethoxan cause high environmental risk.