Estimating nitrogen and phosphorus saturation point for Eichhornia crassipes (Mart.) Solms and Salvinia molesta Mitchell in mesocosms used to treating aquaculture effluent

Abstract

Aim:To evaluate the growth of Eichhornia crassipes (Mart.) Solms and Salvinia molesta Mitchell in tanks used for treating aquaculture effluent and compare the results with literature data in order to estimate the nutrients saturation point. Methods: An experiment with six rectangular fiberglass tanks were separated in two treatments, inflow and outflow (higher and lower nutrient concentration), and the two macrophytes above cited was carried out during 50 days. A floating quadrat with 0.25 m 2 of E. crassipes and S. molesta at inflow and outflow of the tanks was collected weekly for fresh mass measurement. At the beginning and end of the experiment samples of macrophytes were oven-dried at 60 °C until constant weight to determine the dry mass. Dry mass of plants was estimated by a simple linear regression analysis between fresh mass and dry mass (DM). Results: The N and P concentrations were significantly higher (P<0.05) in the inflow (mean of 0.66 mg L -1 and 233.6 mg L -1 , respectively) than in the outflow of the tanks (mean of 0.38 mg L -1 and 174.7 mg L -1 , respectively). However, no significantly different plant growth was observed for either higher or lower concentration. For both higher and lower nutrient concentrations, the biomass gain for E. crassipes was, respectively, 428.5 and 402.7 g DM.m 2 . For S. molesta, biomass gain was 135.2 and 143.1 g DM.m 2 , in the higher and lower concentrations, respectively. Others studies reported high growth of E. crassipes and S. molesta in concentrations of nitrogen (0.14 -0.18 mg L -1 ) and phosphorus (14.2 -77.0 mg L -1 ) lower than this study. Conclusion: The comparison of E. crassipes and S. molesta growth in this study with others allow us to assume that the saturation point of E. crassipes should be 0.26 mg L -1 of nitrogen and 77 mg L -1 of phosphorus and for S. molesta below 0.19 mg L -1 of nitrogen and 15.1 mg L -1 of phosphorus.Keywords: aquatic macrophytes, nutrients, growth, freshwater prawn, effluents.Resumo: Objetivo: Avaliar o crescimento de Eichhornia crassipes (Mart.) Solms e Salvinia molesta Mitchell em tanques utilizados para o tratamento de efluente de aquicultura e comparar os resultados com dados da literatura a fim de estimar o ponto de saturação de nutrientes. Métodos: Um experimento com seis tanques retangulares divididos em dois tratamentos, entrada e saída (maior e menor concentração de nutrientes, respectivamente), e as duas macrófitas aquáticas citadas acima foi realizado durante 50 dias. Um quadrante de 0,25 m 2 com amostras de E. crassipes e S. molesta da entrada e da saída dos tanques foi coletado semanalmente para estimar a massa fresca das macrófitas. No início e no final do experimento amostras das macrófitas foram secas em estufa a 60 °C até peso constante para determinar a massa seca. A massa seca das macrófitas foi estimada por regressão linear simples entre a massa fresca e a massa seca (MS). Resultados: As concentrações de N e P foram significativamente (P<0.05) 2014, vol. 26, no. 4, p. 420 -428 421 Estimating nit...

Treatment of Dairy Effluents in Wetlands Systems With Floating Aquatic Macrophytes

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Experiments on accumulation of phosphorus in the plants Myosotis palustris, Glyceria maxima and Nasturtium officinale

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Use of Eichhornia crassipes dry matter as organic substrate for germination and initial growth of corn

“…Macrophyte overgrowth has led to increasing interest in investigating the potential use of this biomass. Several studies have reported the use of macrophyte biomass as a carbohydrate and protein source in animal feed , Biudes et al 2009 and nutrients removal of organic euents Camargo 2008, Henares andCamargo 2014). The use of macrophytes as fertilizer and organic fertilizer was reported by Sampaio and Oliveira (2005) and Bezerra et al (2007).…”