Avaliação das condições limnológicas e fauna associada de um "wetland" construído em efluente de aquicultura
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Data
2016-06-30
Autores
Marques, Aline Marcari [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As plantas aquáticas são componente importante de um “wetland” construído utilizado para tratamento de efluentes de aquicultura, devido a sua habilidade de absorver nutrientes da água. Estas macrófitas possibilitam melhores condições para microrganismos aquáticos que auxiliam na melhora da qualidade de água. O presente estudo objetivou avaliar o crescimento, a composição química e a fauna associada à Eichhornia crassipes, e as condições físicas e químicas da água e sedimento em um “wetland” (21°11´S; 48°18´O) de uma fazenda de aquicultura, em duas etapas de crescimento da macrófita (Fevereiro à Maio e Julho à Outubro de 2014). A fauna associada a E. crassipes foi amostrada com quadrantes flutuantes (0,09m²); as macrófitas foram lavadas e o plâncton e macrofauna foram fixadas com formalina a 4%; as espécimes foram identificadas e contadas. Diptera, Odonata, Rotifera, Copepoda, Protozoa, Ostracoda and Nematoda estiveram presentes em todas as coletas nas duas etapas de crescimento da E. crassipes. Vorticella sp. foi o gênero dominante nas duas etapas, sendo que Protozoa e Rotifera apresentaram maior abundância. A 1ª etapa de crescimento apresentou maiores valores de nitrogênio e fósforo na água e a 2ª etapa a maior retenção de nutrientes no sedimento antes do banco de aguapé. De acordo com os resultados obtidos foi possível comprovar que o tempo máximo que a E. crassipes deve ser mantida no “wetland” para retenção dos resíduos provenientes da aquicultura é de 60 dias, sendo necessária a retirada total após este período. O aumento da diversidade e da riqueza de espécies foram acompanhados com o crescimento da biomassa do aguapé no período de menor precipitação, mas não houve relação com a qualidade de água e de sedimento. O papel da macrófita é importante para manter a alta diversidade de organismos, mas também para manter qualidade da água do efluente devido a acumulação de nutrientes na biomassa vegetal.
The aquatic plants are a relevant component of a constructed wetland for the treatment of aquaculture effluents due to their capacity in absorbing nutrients from water. The macrophytes provide better conditions for aquatic microorganisms to improve water quality. Current research evaluated the growth, chemicals composition and fauna associated with Eichhornia crassipes, the physical and chemical conditions of water, and sediment within the system for effluent treatment on an aquaculture farm (21°11´S; 48°18´W) at two growth periods of aquatic plant growth (February to May and July to October 2014). Fauna associated to E. crassipes were sampled with floating quadrants (0.09 m²); the macrophytes were washed and the plankton and macrofauna were fixed with 4% formalin; the specimens were then identified and counted. Diptera, Odonata, Rotifera, Copepoda, Protozoa, Ostracoda and Nematoda occurred at all collections in both periods of E. crassipes growth. Vorticella sp. was the predominant genus in the two periods; Protozoa and Rotifera species were the most abundant. The first period of growth revealed higher nitrogen and phosphorus rates in the water, whilst in the second period there was a greater nutrient retention in the sediment in front of the stand of macrophyte. Results showed that 60 days is the maximum time that E. crassipes may be maintained in the wetland to retain wastes from aquaculture; after this period biomass and the accumulation of nutrients in the vegetal tissue decreased. Total removal is mandatory after this period. Increased diversity and species richness followed the growth of biomass of aquatic plant in period of low rainfall, but with no relationship with water quality and sediment. The role of macrophytes is important for maintaining high diversity of organisms, but also to maintaining desirable water-effluent quality due to the accumulation of nutrients in the vegetal biomass.
The aquatic plants are a relevant component of a constructed wetland for the treatment of aquaculture effluents due to their capacity in absorbing nutrients from water. The macrophytes provide better conditions for aquatic microorganisms to improve water quality. Current research evaluated the growth, chemicals composition and fauna associated with Eichhornia crassipes, the physical and chemical conditions of water, and sediment within the system for effluent treatment on an aquaculture farm (21°11´S; 48°18´W) at two growth periods of aquatic plant growth (February to May and July to October 2014). Fauna associated to E. crassipes were sampled with floating quadrants (0.09 m²); the macrophytes were washed and the plankton and macrofauna were fixed with 4% formalin; the specimens were then identified and counted. Diptera, Odonata, Rotifera, Copepoda, Protozoa, Ostracoda and Nematoda occurred at all collections in both periods of E. crassipes growth. Vorticella sp. was the predominant genus in the two periods; Protozoa and Rotifera species were the most abundant. The first period of growth revealed higher nitrogen and phosphorus rates in the water, whilst in the second period there was a greater nutrient retention in the sediment in front of the stand of macrophyte. Results showed that 60 days is the maximum time that E. crassipes may be maintained in the wetland to retain wastes from aquaculture; after this period biomass and the accumulation of nutrients in the vegetal tissue decreased. Total removal is mandatory after this period. Increased diversity and species richness followed the growth of biomass of aquatic plant in period of low rainfall, but with no relationship with water quality and sediment. The role of macrophytes is important for maintaining high diversity of organisms, but also to maintaining desirable water-effluent quality due to the accumulation of nutrients in the vegetal biomass.
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Palavras-chave
Planta aquática, Fauna associada, Aquicultura, Tratamento biológico, Efluente, Aquatic plant, Associated fauna, Aquaculture, Biological treatment, Effluent