Eficiência de macrófitas aquáticas no tratamento de efluentes de viveiro de tilápia do Nilo

Os efluentes de piscicultura podem aumentar a quantidade de sólidos em suspensão e promover o enriquecimento de nitrogênio e fósforo nos ecossistemas aquáticos. Neste contexto, o objetivo deste trabalho foi avaliar a eficiência de três espécies de macrófitas aquáticas flutuantes (Eichhornia crassipes, Pistia stratiotes e Salvinia molesta) no tratamento de efluentes do viveiro de tilápia do Nilo. O efluente foi proveniente de um viveiro com 1000 m² contendo 2000 machos de tilápia do Nilo (Oreochromis niloticus). Os sistemas de tratamento consistiram de 12 taques experimentais, três tanques para cada espécie de macrófita estudada, e três tanques sem plantas (controle). Amostras foram coletadas da água de abastecimento do tanque de tilápia do Nilo (i); do efluente do viveiro com tilápia do Nilo (ii) e dos efluentes tratados pelas macrófitas aquáticas (iii). As seguintes variáveis foram determinadas: turbidez, nitrogênio total, nitrogênio dissolvido, N-amoniacal, N-nitrato, N-nitrito, e fósforo total e fósforo dissolvido. E. crassipes e P. stratiotes foram mais eficientes na remoção de fósforo total (82,0% e 83,3%, respectivamente) e nitrogênio total (46,1% e 43,9%, respectivamente) do que quando comparadas com S. molesta (72,1% de fósforo total e 42,7% de nitrogênio total) e com o controle (50,3% de fósforo total e 22,8% de nitrogênio total). Pode-se concluir que as macrófitas aquáticas, principalmente E. crassipes e P. stratiotes foram eficientes na remoção de nitrogênio e fósforo dos efluentes de criação de tilápia do Nilo. Desta forma, o efluente tratado pode ser utilizado nas próprias atividades de aqüicultura.The effluents from fish farming can increase the quantity of suspended solids and promote the enrichment of nitrogen and phosphorus in aquatic ecosystems. In this context, the aim of this work was to evaluate the efficiency of three species of floating aquatic macrophytes (Eichhornia crassipes, Pistia stratiotes and Salvinia molesta) to treat effluents from Nile tilapia culture ponds. The effluent originated from a 1,000-m² pond stocked with 2,000 male Nile tilapia Oreochromis niloticus. The treatment systems consisted of 12 experimental tanks, three tanks for each macrophyte species, and three control tanks (without plants). Water samples were collected from the: (i) fish pond source water, (ii) effluent from fish pond and (iii) effluents from the treatment tanks. The following water variables were evaluated: turbidity, total and dissolved nitrogen, ammoniacal-N, nitrate-N, nitrite-N, total phosphorus and dissolved phosphorus. E. crassipes and P. stratiotes were more efficient in total phosphorus removal (82.0% and 83.3%, respectively) and total nitrogen removal (46.1% and 43.9%, respectively) than the S. molesta (72.1% total phosphorus and 42.7% total nitrogen) and the control (50.3% total phosphorus and 22.8% total nitrogen), indicating that the treated effluents may be reused in the aquaculture activity

Assessment of environmental, social and economic sustainability of a hydrographic basin in the Brazilian semiarid region

O objetivo do presente estudo foi avaliar a sustentabilidade ambiental, social e econômica da bacia hidrográfica do rio Apodi/Mossoró (RN), semiárido brasileiro. A bacia foi dividida em quatro trechos: alto curso, médio curso superior, médio curso inferior e baixo curso. Os locais de amostragens foram distribuídos ao longo da bacia hidrográfica para obtenção dos valores das seguintes variáveis limnológicas: oxigênio dissolvido, nitrogênio total, fósforo total e coliformes termotolerantes. As informações relacionadas aos indicadores econômicos e sociais foram adquiridas junto ao Instituto Brasileiro de Geografia e Estatística – IBGE. A sustentabilidade foi avaliada por meio do modelo conceitual implementado com o auxílio do software Multisectorial, Integrated and Operational Decision Support System for Sustainable Use of Water Resources at the Catchment Scale (MULINO mDSS). Na bacia hidrográfica do rio Apodi/Mossoró o trecho mais sustentável foi o baixo curso, com menor amplitude de variação entre os escores das dimensões econômica, ambiental e social. Este trecho foi considerado como potencialmente sustentável, apresentando melhor desempenho nas dimensões social e econômica, no entanto, comparativamente, exibiu menor escore para a dimensão ambiental do que os demais trechos da bacia hidrográfica. Isto evidencia que o trecho de baixo curso possui maior desenvolvimento econômico e social, entretanto, apresenta mais problemas ambientais. O trecho de alto curso foi classificado como de baixa sustentabilidade. Já o trecho de médio curso superior se destacou na dimensão ambiental, mas por não apresentar escores proporcionais nas dimensões social e econômica, o seu índice geral foi de baixa sustentabilidade. O trecho de médio curso inferior apresentou média sustentabilidade. Assim, foi evidenciado que ambientes que são mais desenvolvidos economicamente tendem a apresentar mais problemas ambientais, entretanto, ainda podem ser considerados mais sustentáveis devido ao maior desenvolvimento econômico e social.The objective of the present study is to evaluate the environmental, social and economic sustainability of the Apodi/Mossoró River hydrographic basin (RN) located in the Brazilian semiarid region. The basin was divided into four sections: upper course, upper middle course, lower middle course, and lower course. The sampling sites were distributed along the hydrographic basin to obtain the values of the following limnological variables: dissolved oxygen, total nitrogen, total phosphorus and thermotolerant coliforms. Information related to economic and social indicators was acquired from the Brazilian Institute of Geography and Statistics (IBGE). Sustainability was assessed using the conceptual model implemented with the aid of the software Multisectorial, Integrated and Operational Decision Support System for Sustainable Use of Water Resources at the Catchment Scale (MULINO mDSS). In the Apodi/Mossoró river basin, the most sustainable stretch was the lower course, with less variation amplitude between the scores of the economic, environmental and social dimensions. This stretch was considered potentially sustainable, with better performance in the social and economic dimensions; however, comparatively, it showed lower score for the environmental dimension than the other sections of the hydrographic basin. This fact shows that the lower course section has greater economic and social development, however, presents more environmental problems. The upper course section was classified as having low sustainability. The upper middle course section stood out in the environmental dimension, but because it did not present proportional scores in the social and economic dimensions, its overall index was of low sustainability. The lower middle course section showed average sustainability. Thus, it was shown that environments that are more economically developed tend to have more environmental problems, however, they can still be considered more sustainable due to greater economic and social development

Distribution and density of the bivalve Tivela mactroides (Born, 1778) in the tropical estuarine region of semiarid Northeast Brazil

The present study evaluated the distribution (spatial and temporal) and density of the mollusc Tivela mactroides on beaches in a tropical estuarine region of the Brazilian semiarid region and their relationship with temperature, salinity, organic matter and sediment grain size. Semiannually (April 2009 to October 2011), 20 transects were arranged perpendicular to the line of the beach towards the sea, 300 m long in the intertidal zone. Seven sampling points, 50 m apart, were established in each transect, and samples of molluscs and sediment were collected. The highest average densities of T. mactroides were observed in April 2009 (43 individuals/m2) and October 2009 (45 individuals/m²), while the lowest values were found in April 2010 and October 2010 (11 and 7 individuals/m², respectively). The lower density in these months was probably related to the intense rainfall that caused a decrease in salinity in the region. The correlation between density of T. mactroides and distance from the estuary of the Apodi-Mossoró River was positive, indicating an increase in the number of individuals of this species with distance from the estuarine region. The density of T. mactroides was negatively correlated with the percentage of organic matter. It was also found that this species has an aggregated distribution pattern

Influence of aquaculture effluents on the growth of Salvinia molesta Influência do efluente de aqüicultura sobre o crescimento de Salvinia molesta

Abstract: Objective: Aquaculture generates social and economic benefits, but also causes impacts on the environment. One of the major impacts is the release of untreated effluents into rivers, reservoirs, and lakes, which can affect aquatic populations and communities. In this study, we tested the hypothesis that effluent from aquaculture favors the growth of the floating aquatic macrophyte Salvinia molesta; Methods: The study was carried out in a non-impacted reservoir (NIR) and in another reservoir (IR) that is impacted by discharges of aquaculture effluents, and lasted for nine months. In each of the reservoirs, we installed four experimental units containing 10 ramets of S. molesta. Monthly, we measured limnological variables of the water and the biomass of S. molesta in both reservoirs; Results: The temperature, turbidity, electrical conductivity, alkalinity, chlorophyll-a, total Kjeldahl nitrogen, and total phosphorus were higher in the IR in all the collection months. At the end of the experiment, the concentrations of total nitrogen and phosphorus in the biomass of S. molesta from the IR were higher than those in plants from the NIR. The estimated support capacity (K) for S. molesta in the NIR was 3.0 ± 0.7 g DM.m -2 and in the IR was 37.4 ± 2.4 g DM.m -2 ; Conclusions: It was concluded that the discharge of aquaculture effluent modifies the limnological characteristics of the water of the receiving reservoir, and that the growth of Salvinia molesta is favored by the aquaculture effluent, because of the increases in the concentrations of nitrogen and phosphorus in the water. Keywords: floating aquatic macrophyte, nutrients, support capacity, eutrophication, chemical composition. Resumo: Objetivo: A aqüicultura gera benefícios sociais e econômicos, mas também causa impactos ao ambiente. Um dos principais impactos é o lançamento de efluentes sem tratamento em ambientes como rios, reservatórios e lagos, o que pode afetar populações e comunidades aquáticas. Neste trabalho foi testada a hipótese de que o efluente de aqüicultura favorece o crescimento da macrófita aquática flutuante Salvinia molesta; Métodos: O estudo foi realizado em uma represa não impactada (RNI) e outra represa impactada (RI) por lançamentos de efluentes de aqüicultura e teve duração de nove meses. Em cada uma das represas foram fixadas quatro unidades experimentais contendo 10 rametes de S. molesta. Mensalmente, foram determinadas variáveis limnológicas da água e a biomassa de S. molesta nas duas represas; Resultados: Os valores de temperatura, turbidez, condutividade elétrica, alcalinidade, clorofila-a, nitrogênio Kjeldahl total e fósforo total foram superiores na RI em todos os meses do estudo. As concentrações de nitrogênio e fósforo total na biomassa de S. molesta da RI foram maiores do que as da RNI, ao final do experimento. Os valores de capacidade suporte (K) para S. molesta na RNI foram de 3,0 ± 0,7 g MS.m -2 e na RI foi de 37,4 ± 2,4 g MS.m -2 ; Conclusões: Concluiu-se que o lançamento de efluente de aqüicultura modifica as características limnológicas da água da represa receptora e que o crescimento de Salvinia molesta é favorecido pelo efluente de aqüicultura, provavelmente, devido ao aumento das concentrações de nitrogênio e fósforo na água. Palavras-chave: macrófita aquática flutuante, nutrientes, capacidade suporte, eutrofização, composição química. Biological Limnolog

Tratamento de efluentes de carcinicultura por macrófitas aquáticas flutuantes Treatment of shrimp effluents by free-floating aquatic macrophytes

Avaliou-se neste estudo a eficiência de sistemas compostos de duas espécies de macrófitas aquáticas flutuantes (Eichhornia crassipes e Pistia stratiotes) no tratamento de efluentes gerados por um viveiro de manutenção de reprodutores de camarões-canela (Macrobrachium amazonicum). Os sistemas de tratamento foram constituídos de 12 unidades experimentais com as macrófitas aquáticas e três sem plantas (controle). Foram analisadas amostras da água de abastecimento do viveiro de criação de camarões-d'água-doce, do efluente gerado e dos efluentes tratados. A remoção de nutrientes não diferiu significativamente entre as duas espécies vegetais. As maiores remoções foram obtidas para fósforo total (41,9% pelo controle; 71,6% por E. crassipes; 69,9% por P. stratiotes; 72,5% por E. crassipes + P. stratiotes e 72,1% por P. stratiotes + E. crassipes) e para turbidez (30,6% pelo controle; 80,2% por E. crassipes; 75,2% por P. stratiotes; 79,8% por E. crassipes + P. stratiotes e 81,5% por P. stratiotes + E. crassipes). As macrófitas aquáticas foram eficientes na remoção de nitrogênio e fósforo dos efluentes de criação de M. amazonicum.<br>The efficiency of systems composed of two species of floating aquatic macrophyte (Eichhornia crassipes and Pistia stratiotes) to treat effluents from shrimp culture was evaluated in this research. The effluent originated from a pond populated with Macrobrachium amazonicum. Treatment systems consisted of 12 experimental tanks with aquatic macrophyte and three tanks without plants (control). Water samples were collected from the fresh water supply and before and after passing through the treatment systems. There are no differences in the removal of nutrients between the two species. The higher nutrient removal was observed for total phosphorus (41.9% by control; 71.6% by E. crassipes; 69.9 by P. stratiotes; 72.5% by E. crassipes + P. stratiotes and 72.1 by P. stratiotes + E. crassipes) and turbidity (30.6% by control; 80.2% by E. crassipes; 75.2 by P. stratiotes; 79.8% by E. crassipes + P. stratiotes and 81.5 by P. stratiotes + E. crassipes). The systems containing aquatic macrophytes were efficient in nitrogen and phosphorus removal from M. amazonicum culture

Valor nutritivo de macrófitas aquáticas flutuantes (Eichhornia crassipes, Pistia stratiotes e Salvinia molesta) utilizadas no tratamento de efluentes de aqüicultura

The aim of this study was to evaluate the nutritive value of free-floating aquatic macrophytes, Eichhornia crassipes (Mart.) Solms (Pontederiaceae), Pistia stratiotes (L.) (Araceae) and Salvinia molesta (Mitchell) (Salviniaceae) used in a Nile tilapia (Oreochromis niloticus) waste treatment, and these species biomass potential uses. The vegetal biomass samples were collected from 0.25 m² floating squares and divided in aerial and submerse parts, to determine the concentrations of cell wall fraction, soluble carbohydrates, polyphenols, lipids, crude protein and total phosphorus. The higher nutritive value was observed in E. crassipes and S. molesta aerial parts, and in P. stratiotes total biomass, due to their lower cell wall fraction mean rates (60.7; 64.2 and 56.9 % dry mass, respectively) and to the higher rates of: crude protein (10.1; 9.1 and 8.8 % dry mass, respectively), soluble carbohydrates (26.6; 18.7 and 12.4 mg.g-1 dry mass, respectively) and lipids (7.6; 4.5 and 4.4% dry mass, respectively). It may be concluded that P. stratiotes total biomass, and E. crassipes and S. molesta aerial biomass have nutritive values with potential use for ruminant feeding or as ration ingredients.O objetivo deste estudo foi avaliar o valor nutritivo das macrófitas aquáticas flutuantes, Eichhornia crassipes (Mart.) Solms (Pontederiaceae), Pistia stratiotes (L.) (Araceae) e Salvinia molesta (Mitchell) (Salviniaceae), utilizadas em um sistema de tratamento de efluentes de tilápia do Nilo (Oreochromis niloticus), e inferir sobre o potencial de aproveitamento da biomassa dessas espécies. As amostras de biomassa vegetal foram obtidas através de um quadrado de 0,25m2 de área e separadas em partes aérea e submersa para a determinação dos teores de fração de parede celular, carboidratos solúveis, polifenóis, lipídios, proteína bruta e fósforo total. O maior valor nutritivo foi observado na parte aérea de E. crassipes e S. molesta e na biomassa total de P. stratiotes devido aos menores valores médios de fração de parede celular (60,7; 64,2 e 56,9 % PS, respectivamente) e aos teores mais elevados de proteína bruta (10,1; 9,1 e 8,8% PS, respectivamente), carboidratos solúveis (26,16; 18,7 e 12,4 mg.g-1 PS, respectivamente) e lipídios (7,6; 4,5 e 4,4 % PS, respectivamente). Conclui-se que a biomassa total de P. stratiotes e a biomassa aérea de E. crassipes e S. molesta têm valor nutritivo com potencial para uso na alimentação de ruminantes ou na formulação de rações

Efficiency of aquatic macrophytes to treat Nile tilapia pond effluents

The effluents from fish farming can increase the quantity of suspended solids and promote the enrichment of nitrogen and phosphorus in aquatic ecosystems. In this context, the aim of this work was to evaluate the efficiency of three species of floating aquatic macrophytes (Eichhornia crassipes, Pistia stratiotes and Salvinia molesta) to treat effluents from Nile tilapia culture ponds. The effluent originated from a 1,000-m² pond stocked with 2,000 male Nile tilapia Oreochromis niloticus. The treatment systems consisted of 12 experimental tanks, three tanks for each macrophyte species, and three control tanks (without plants). Water samples were collected from the: (i) fish pond source water, (ii) effluent from fish pond and (iii) effluents from the treatment tanks. The following water variables were evaluated: turbidity, total and dissolved nitrogen, ammoniacal-N, nitrate-N, nitrite-N, total phosphorus and dissolved phosphorus. E. crassipes and P. stratiotes were more efficient in total phosphorus removal (82.0% and 83.3%, respectively) and total nitrogen removal (46.1% and 43.9%, respectively) than the S. molesta (72.1% total phosphorus and 42.7% total nitrogen) and the control (50.3% total phosphorus and 22.8% total nitrogen), indicating that the treated effluents may be reused in the aquaculture activity

Valor nutritivo de macrófitas aquáticas flutuantes (Eichhornia crassipes, Pistia stratiotes e Salvinia molesta) utilizadas no tratamento de efluentes de aqüicultura

The aim of this study was to evaluate the nutritive value of free-floating aquatic macrophytes, Eichhornia crassipes (Mart.) Solms (Pontederiaceae), Pistia stratiotes (L.) (Araceae) and Salvinia molesta (Mitchell) (Salviniaceae) used in a Nile tilapia (Oreochromis niloticus) waste treatment, and these species biomass potential uses. The vegetal biomass samples were collected from 0.25 m 2 floating squares and divided in aerial and submerse parts, to determine the concentrations of cell wall fraction, soluble carbohydrates, polyphenols, lipids, crude protein and total phosphorus. The higher nutritive value was observed in E. crassipes and S. molesta aerial parts, and in P. stratiotes total biomass, due to their lower cell wall fraction mean rates (60.7; 64.2 and 56.9 % dry mass, respectively) and to the higher rates of: crude protein (10.1; 9.1 and 8.8 % dry mass, respectively), soluble carbohydrates (26.6; 18.7 and 12.4 mg.g -1 dry mass, respectively) and lipids (7.6; 4.5 and 4.4% dry mass, respectively). It may be concluded that P. stratiotes total biomass, and E. crassipes and S. molesta aerial biomass have nutritive values with potential use for ruminant feeding or as ration ingredients