Remobilization of leaf Na+ content and use of nonstructural carbohydrates vary depending on the time when salt stress begins in woody species.

Basic mechanisms are known to promote salt tolerance in plants: a delay in Na+ uptake or rapid Na+ remobilization from leaf tissue. We measured dynamics of the Na+/K+ ratio and components of carbon metabolism during the first 72 h after saline stress (200 mM NaCl) began in Cenostigma pyramidale, a woody species, under controlled conditions. Saline stress at two times: one plant group at the beginning of the morning and the other in the evening. Stressed plants had three times more Na+ in leaves than did control plants in the first 24 h. However, in the next few hours, despite new applications of saline solution, the Na+/K+ ratio continued to decline. Several samples, including night treatments, provided evidence that this species uses Na+ recirculation mechanisms to endure salt stress. Effects of salt on the traits evaluated differed depending on the time when stress began. Between the two saline treatments, in the first 24 h after saline stress, gas exchange decreased more strongly in morning-stressed plants, when large amounts of Na+ reached the leaf and K+ left this organ. Nevertheless, when stress was applied in the evening, leaf Na+ remobilization was faster, and the soluble sugar/starch ratio remained greater than did the control. Our data suggested that time of the beginning of salt stress could change the level of damage. Morning-stressed plants synthesized greater amounts of proline, H2O2, and malondialdehyde than did night-stressed plants. We recommend that details regarding the time of stress be taken into consideration in physiological studies.

Growth of Geophagus brasiliensis reared at different temperatures and feeding regimes / Crescimento de Geophagus brasiliensis cultivado em diferentes temperaturas e regimes de alimentação

The aim of this study was to evaluate the growth performance of Geophagus brasiliensis reared under distinct temperatures (24.3 ± 0.9, 28.1 ± 1.0, and 31.7 ± 0.8°C) and feeding regimes (apparent satiety and a supply of 4% of the total biomass). About 500 wild-caught individuals were sorted and identified, to screen 180 fish to be used in the experiment (6.81 ± 1.15 g and 7.51 ± 0.47 cm). After a 55-day acclimatization period, the fish were distributed in experimental tanks, considering a double factorial randomized blocks scheme, composed of six treatments and three replicates. Growth performance parameters, somatic indexes and carcass yield were evaluated at the end of the experimental period (72 days). Fish fed to the point of apparent satiety presented higher (p <0.05) final weight, weight gain, specific growth rate and hepatosomatic index. The animals reared at a temperature of 24.3°C displayed higher (p <0.05) final weight, weight gain, specific growth, hepatosomatic index, lower visceral fat, and feed conversion index. It was concluded that G. brasiliensis presents higher productive indexes when fed until apparent satiety and reared in temperatures close to 24.3°C.

O objetivo deste estudo foi avaliar o desempenho zootécnico de Geophagus brasiliensis criado sob diferentes temperaturas (24,3 ± 0,9, 28,1 ± 1,0 e 31,7 ± 0,8°C) e regimes alimentares (saciedade aparente e taxa de arraçoamento de 4% da biomassa total). Foram selecionados e identificados cerca de 500 indivíduos capturados na natureza, para a triagem de 180 peixes a serem utilizados no experimento (6,81 ± 1,15 g e 7,51 ± 0,47 cm). Após um período de aclimatação de 55 dias, os peixes foram distribuídos em tanques experimentais, considerando um esquema de blocos ao acaso em fatorial duplo, composto por seis tratamentos e três repetições. O desempenho zootécnico, os índices somáticos e o rendimento de carcaça foram avaliados ao final do período experimental (72 dias). Os peixes alimentados até a saciedade aparente apresentaram maiores (p <0,05) peso final, ganho de peso, taxa de crescimento específico e índice hepatossomático. Os animais criados em temperatura de 24,3°C apresentaram maior (p <0,05) peso final, ganho de peso, crescimento específico, índice hepatossomático, menor índice de gordura visceral e de conversão alimentar. Concluiu-se que G. brasiliensis apresenta maiores índices produtivos quando alimentado até a saciedade aparente e criado em temperaturas próximas a 24,3°C.

Growth of Geophagus brasiliensis reared at different temperatures and feeding regimes / Crescimento de Geophagus brasiliensis cultivado em diferentes temperaturas e regimes de alimentação

The aim of this study was to evaluate the growth performance of Geophagus brasiliensis reared under distinct temperatures (24.3 ± 0.9, 28.1 ± 1.0, and 31.7 ± 0.8°C) and feeding regimes (apparent satiety and a supply of 4% of the total biomass). About 500 wild-caught individuals were sorted and identified, to screen 180 fish to be used in the experiment (6.81 ± 1.15 g and 7.51 ± 0.47 cm). After a 55-day acclimatization period, the fish were distributed in experimental tanks, considering a double factorial randomized blocks scheme, composed of six treatments and three replicates. Growth performance parameters, somatic indexes and carcass yield were evaluated at the end of the experimental period (72 days). Fish fed to the point of apparent satiety presented higher (p <0.05) final weight, weight gain, specific growth rate and hepatosomatic index. The animals reared at a temperature of 24.3°C displayed higher (p <0.05) final weight, weight gain, specific growth, hepatosomatic index, lower visceral fat, and feed conversion index. It was concluded that G. brasiliensis presents higher productive indexes when fed until apparent satiety and reared in temperatures close to 24.3°C.(AU)

O objetivo deste estudo foi avaliar o desempenho zootécnico de Geophagus brasiliensis criado sob diferentes temperaturas (24,3 ± 0,9, 28,1 ± 1,0 e 31,7 ± 0,8°C) e regimes alimentares (saciedade aparente e taxa de arraçoamento de 4% da biomassa total). Foram selecionados e identificados cerca de 500 indivíduos capturados na natureza, para a triagem de 180 peixes a serem utilizados no experimento (6,81 ± 1,15 g e 7,51 ± 0,47 cm). Após um período de aclimatação de 55 dias, os peixes foram distribuídos em tanques experimentais, considerando um esquema de blocos ao acaso em fatorial duplo, composto por seis tratamentos e três repetições. O desempenho zootécnico, os índices somáticos e o rendimento de carcaça foram avaliados ao final do período experimental (72 dias). Os peixes alimentados até a saciedade aparente apresentaram maiores (p <0,05) peso final, ganho de peso, taxa de crescimento específico e índice hepatossomático. Os animais criados em temperatura de 24,3°C apresentaram maior (p <0,05) peso final, ganho de peso, crescimento específico, índice hepatossomático, menor índice de gordura visceral e de conversão alimentar. Concluiu-se que G. brasiliensis apresenta maiores índices produtivos quando alimentado até a saciedade aparente e criado em temperaturas próximas a 24,3°C.(AU)

Biodegradabilidad de lixiviados procedentes de un relleno sanitario utilizando un sistema de lodos activados flujo pistón / The biodegradability of leachates from a landfill using an activated sludge processes plug flow reactor system / Biodegradabilidade de lixiviados de um aterro usando um sistema de lodos ativados de fluxo de pistão

Resumen En esta investigación se desarrolló un Reactor Flujo Pistón (RFP) de lodos activados, que fue empleado para determinar el Tiempo de Retención Celular (TRC) óptimo para tratar cargas altas de lixiviado y estimar el comportamiento cinético del sistema con el fin que sirva de base para proyecciones de escalamiento y diseño de reactor de este tipo a escala real. Para ello se realizó el diseño, la construcción y puesta en marcha del RFP a nivel de laboratorio (capacidad de 50L) en condiciones de operación continua con recirculación de lodo y se utilizó como sustrato lixiviado procedente del relleno sanitario El Guayabal de la ciudad de Cúcuta. Se determinó como parámetros de control cuatro TRC diferentes entre 5 y 20 días diferenciada por etapas. Se evaluaron las variables de pH, Temperatura, Oxígeno disuelto y Sólidos Suspendidos Volátiles en el Licor Mixto (SSVLM). En cuanto al control y monitoreo de la eficiencia de remoción se escogió la Demanda Química de Oxígeno (DQO) como parámetro para medir la degradación de materia orgánica, dado que este parámetro a diferencia de la Demanda Bioquímica de Oxígeno (DBO5) puede ser calculado en un menor tiempo. El sistema biológico RFP alcanzó estabilizarse en un período de operación entre 20 y 25 días con remociones promedio mayores a 92% para TRC de 15 y 20 días mientras que TRC menores reportaron remociones promedio por debajo del 86%. Así mismo TRC de 15 permitió un Factor de carga (F/M) óptima promedio de 1.1 KgDQO/KgSSV.d. Las constantes cinéticas obtenidas en esta investigación, representativas para un sistema de RFP operado a escala laboratorio para remoción de materia orgánica carbonacea en lixiviados fueron: KS= 836.5 mg/L DQO, k=4.8123 d1, Y= 0.089 mg SSVLM/mg DQO y kd= 0.018 d-1, ajustados por regresión al modelo matemático de Lawrence y McCarty al poseer una correlación de 0.97 entre los datos experimentales obtenidos y el modelo y amplia aplicación en el campo de diseño de reactores de lodos activados.

Abstract An activated sludge processes (ASP) plug flow reactor (PFR) was developed in this research and used for determining optimal cell residence time (CRT) for treating high leachate loads and estimating the system's kinetic behaviour as a basis for scaling projections and this type of reactor design at full-scale. The RFP was designed, built and put into operation in the laboratory (50L capacity) involving continuous operation conditions with sludge recirculation; leached substrate from the city of Cúcuta's El Guayabal landfill was used. Four 5-day CRTs (ranging from 5 to 20 days) were used as control parameters. Variables were evaluated regarding pH, temperature, dissolved oxygen and mixed liquor volatile suspended solids (MLVSS). Regarding removal efficiency control and monitoring, chemical oxygen demand (COD) was chosen as a parameter for measuring organic matter degradation since COD (unlike biochemical oxygen demand (BOD5)) can be calculated in a shorter time. The RFP biological system became stabilised in a 20- to 25-day operating period, having greater than 92% average removal for 15- and 20-day CRTs, whilst lower CRTs reported lower than 86% average removal. A 15-day TRC gave an average 0.26 kgDQO/kgSSV.d optimal load factor (F/M). The representative kinetic constants obtained in this research for a laboratory-scale PFR system for the removal of carbonaceous organic matter in leachates were KS = 836mg COD / l, k = 4.8123 d1, Y = 0.089 mg SSVLM / mg COD and kd = 0.018 d-1, adjusted by regression using Lawrence and McCarty's mathematical model (having 0.97 correlation between the experimental data and the model). Such model should have broad application in the field of ASP-type PFRs.

Resumo Nesta pesquisa, um Reator de lodo ativado de Fluxo de Pistão (RFP) foi desenvolvido para determinar o Tempo de Retenção Celular (CRT) ideal para tratar altas cargas de lixiviado e estimar o comportamento cinético do sistema, a fim de servir de base para projetar o reator em escala real. Para isso, foram realizados RFP em nível de laboratório (capacidade de 50L) em condições de operação contínua com recirculação de lodo e foi utilizada como substrato lixiviado do aterro El Guayabal na cidade de Cúcuta. Usando quatro diferentes CRTs entre 5 e 20 dias como fatores de bloqueio. Foram avaliadas as variáveis ​​pH, Temperatura, Oxigênio Dissolvido e Sólidos Suspensos Voláteis no Licor Misto (SSVLM). Em relação ao controle e monitoramento da eficiência de remoção, a Demanda Química de Oxigênio (DQO) foi escolhida como parâmetro para medir a degradação da matéria orgânica, uma vez que este parâmetro, ao contrário da Demanda Bioquímica de Oxigênio (DBO5), pode ser calculado em um tempo mais curto. O sistema biológico da RFP se estabilizou em um período de operação entre 20 e 25 dias com remoções médias superiores a 92% para TRC de 15 e 20 dias, enquanto TRC menores mostraram remoções médias abaixo de 86%. Da mesma forma, TRC de 15 dias permitiu um fator de carga ideal médio (F / M) de 0,26 KgDQO / d. As constantes cinéticas obtidas nesta pesquisa, representativas de um sistema RFP operado em escala de laboratório para remoção de matéria orgânica carbonácea em lixiviados foram: KS = 836mg COD / l, k = 4,8123 d1, Y = 0,089 mg SSVLM / mg COD e kd = 0,018 d-1, ajustado por regressão ao modelo matemático de Lawrence e McCarty, tendo uma correlação de 0,97 entre os dados experimentais obtidos e o modelo e ampla aplicação na área de projeto de reatores de lodo ativado.

Aquaponic System with White Shrimp Litopenaeus vannamei Rearing and Production of the Plants Batis maritima, Sarcocornia neei and Sporobolus virginicus

Abstract Aquaponics is a system that integrates aquaculture with plant production in which two species are benefited, and there is water saving. In this study was carried out with an aquaponic system to verify the interaction between the growth of the halophytes Batis maritime, Sarcocornia neei, and Sporobolus virginicus associated with white shrimp Litopenaeus vannamei rearing. We also investigated if there were different responses of physicochemical variables of the water in the experimental shrimp culture ponds integrated into the growth of plants and control ponds, without plants, throughout a 56-day period. The treatment experiment and control presented a statistically significant difference in total dissolved solids, salinity, total suspended solids, ammonia, orthophosphate, and nitrite. In the experimental treatment, with the presence of plants and recirculating water, a reduction of total suspended solids, ammonia and orthophosphate was observed. The rate of shrimp production was not significantly different between treatments, and the performance was similar to that of other studies. The biomass gain of the halophyte B. maritima was 876.6 grams in 0.5 m² and of S. neei was 48.8 grams in 0.16 m². All plants of the species S. virginicus died during the experiment.

Does intensive feeding frequency affect growth performance of common snook Centropomus undecimalis (Bloch, 1792)? / A utilização de frequência alimentar elevada pode afetar o desempenho produtivo do robalo flecha Centropomus undecimalis (Bloch, 1792)?

Abstract Salt water recirculation systems using automatic feeders are a new frontier for marine aquaculture. It is possible to decrease the vulnerability of the traditional fish farming in open systems and reduce wasteful feeding and discharge of effluents, as well as increase the economic returns. An experiment with common snook fingerings (4.31 ± 1.42 g and 8.4 ± 1.0 cm) was performed. Three feeding treatments were evaluated: six, twelve and eighteen feeding times per day. Each treatment had three replications. Among the three tested frequencies (fed 6, 12 and 18 times a day), the feeding frequency of 12 times per day (every two hours) showed the best values of the parameters evaluated for production performance. The final weight values, condition factor, specific growth rate and daily weight gain of the treatment 12 feeding times per day were all significantly higher than the lower and higher frequencies. Our results demonstrate that high feeding frequency is not synonymous of higher performance, but is extremely necessary to find out the best range for the target species. Besides, this relationship between feeding frequency and growth performance might change over weight range. Therefore, future studies should address higher weight ranges for comparison to our results.

Resumo Sistemas de recirculação de água salgada utilizando alimentadores automáticos são uma nova fronteira para a aquicultura marinha. Possibilitam diminuir a vulnerabilidade dos cultivos em sistemas abertos e conferir redução de desperdício de ração e lançamento de efluentes, assim como elevar o retorno econômico. Foi realizado um experimento com juvenis de Robalo-flecha (4,31 ± 1,42 g e 8,4 ± 1,0 cm). Três frequências alimentares foram avaliadas: alimentação seis vezes ao dia; doze vezes ao dia, e; dezoito vezes ao dia. Cada tratamento teve três repetições. Dentre as três frequências avaliadas a frequência alimentar de 12 vezes ao dia foi a que apresentou os melhores valores para os parâmetros zootécnicos avaliados. Os valores obtidos de peso final, fator de condição, taxa de crescimento específico e ganho de peso diário foram todos maiores para a frequência de 12 vezes ao dia do que os obtidos para as frequências maior e menor. Nossos resultados demonstram que elevadas frequências alimentares não são sinônimo de melhor desempenho produtivo, mas é extremamente importante conhecer a frequência ideal para a espécie a ser cultivada. Além disto, a relação entre frequência alimentar e crescimento pode mudar de acordo com a faixa de peso dos indivíduos. Desta forma, é extremamente importante que trabalhos futuros avaliem as frequências aqui estudadas para comparar os resultados em indivíduos maiores.

Influence of recirculation over COD and N-NH4 removals from landfill leachate by horizontal flow constructed treatment wetland.

Treatment of landfill leachate is a challenge due to its complex chemical composition and high recalcitrance and because of high costs for conventional wastewater treatment. In our study, leachate from the Quitaúna Landfill, Sao Paulo Metropolitan Region, Brazil, was treated at a laboratory scale with a horizontal subsurface flow constructed treatment wetland (HF-CTW) operating under a recirculation regime. Two units planted with Heliconia psittacorum (HP) and Cyperus papyrus (CP), and one unplanted control unit were assessed. With a recirculation regime over 21 days, the planted units removed 40% of chemical oxygen demand (COD) while the control unit removed only 29%. True color removal efficiencies were 2, 22, and 23% for the control, HP, and CP HF-CTWs, respectively. The ammonium nitrogen removal efficiencies for a 21-day hydraulic retention time (HRT) were 63-81% for planted units and 72% for the control. The increase of the HRT from 7 to 21 days led to the enhancement of ammonium nitrogen removal but did not affect the COD and total nitrogen removals. This phenomenon is a consequence of leachate's low biodegradability. The present study shows the importance of the HRT and plant presence for landfill leachate treatment using HF-CTWs.

Performance of an aquaponics system using constructed semi-dry wetland with lettuce (Lactuca sativa L.) on treating wastewater of culture of Amazon River shrimp (Macrobrachium amazonicum).

Aquaponics is a science that integrates animal aquatic production with vegetable culture in recirculating water systems. The performance of an aquaponics system using constructed semi-dry wetland with lettuce (Lactuca sativa L.) planted on treating wastewater of culture of shrimp Macrobrachium amazonicum was evaluated. Each aquaponics module consisted in four culture tanks (1 m3 tank-1), conical sedimentation tank (0.1 m3), circular holding tank (0.2 m3), and constructed semi-dry wetland (0.2 m × 1.0 m × 4.0 m). Post larvae (PL) shrimps with an initial average mass of 314 ± 4.75 mg were stocked at density treatments in quadruplicate: (A) 40 shrimps m-2, (B) 80 shrimps m-2, and (C) 120 shrimps m-2. Our results showed the average final mass of shrimps had a slight reduction at the density 80 and 120 shrimps. However, it did not differ significantly between the treatments. The ultimate survival and productivity were higher in density 80 and 120 shrimps. The maximum biomass productivity occurred at the treatment with density 120 shrimps. The aquaponics recirculation system using constructed semi-dry wetlands with lettuce adequately treated the water at the densities tested. Various water quality parameters were deemed suitable for shrimp culture, but for lettuce not, especially the temperature. The shrimp density was inappropriate which limited the system to accumulate and increase the concentration of nutrients to vegetables with lessening the yield. Nonetheless, the system with higher density has higher nutrient content that plants demonstrated significantly better growth and yield. The results showed the potential use of organics waste generated in a family lettuce hydroponic production, but for a commercial production is indicated supplementation with nutrients like calcium, magnesium, and potassium in the water.

Does intensive feeding frequency affect growth performance of common snook Centropomus undecimalis (Bloch, 1792)? / A utilização de frequência alimentar elevada pode afetar o desempenho produtivo do robalo flecha Centropomus undecimalis (Bloch, 1792)?

Salt water recirculation systems using automatic feeders are a new frontier for marine aquaculture. It is possible to decrease the vulnerability of the traditional fish farming in open systems and reduce wasteful feeding and discharge of effluents, as well as increase the economic returns. An experiment with common snook fingerings (4.31 ± 1.42 g and 8.4 ± 1.0 cm) was performed. Three feeding treatments were evaluated: six, twelve and eighteen feeding times per day. Each treatment had three replications. Among the three tested frequencies (fed 6, 12 and 18 times a day), the feeding frequency of 12 times per day (every two hours) showed the best values of the parameters evaluated for production performance. The final weight values, condition factor, specific growth rate and daily weight gain of the treatment 12 feeding times per day were all significantly higher than the lower and higher frequencies. Our results demonstrate that high feeding frequency is not synonymous of higher performance, but is extremely necessary to find out the best range for the target species. Besides, this relationship between feeding frequency and growth performance might change over weight range. Therefore, future studies should address higher weight ranges for comparison to our results.(AU)

Sistemas de recirculação de água salgada utilizando alimentadores automáticos são uma nova fronteira para a aquicultura marinha. Possibilitam diminuir a vulnerabilidade dos cultivos em sistemas abertos e conferir redução de desperdício de ração e lançamento de efluentes, assim como elevar o retorno econômico. Foi realizado um experimento com juvenis de Robalo-flecha (4,31 ± 1,42 g e 8,4 ± 1,0 cm). Três frequências alimentares foram avaliadas: alimentação seis vezes ao dia; doze vezes ao dia, e; dezoito vezes ao dia. Cada tratamento teve três repetições. Dentre as três frequências avaliadas a frequência alimentar de 12 vezes ao dia foi a que apresentou os melhores valores para os parâmetros zootécnicos avaliados. Os valores obtidos de peso final, fator de condição, taxa de crescimento específico e ganho de peso diário foram todos maiores para a frequência de 12 vezes ao dia do que os obtidos para as frequências maior e menor. Nossos resultados demonstram que elevadas frequências alimentares não são sinônimo de melhor desempenho produtivo, mas é extremamente importante conhecer a frequência ideal para a espécie a ser cultivada. Além disto, a relação entre frequência alimentar e crescimento pode mudar de acordo com a faixa de peso dos indivíduos. Desta forma, é extremamente importante que trabalhos futuros avaliem as frequências aqui estudadas para comparar os resultados em indivíduos maiores.(AU)

Performance of fat snook juveniles reared at different temperatures / Desempenho de juvenis de robalo-peva cultivados em diferentes temperaturas

We aimed at evaluating the effects of different water temperatures on the zootechnicalperformance of fat snook. The experiment lasted for 60 days, which was conducted in water recirculationsystems, and was randomly designed with three treatments and three replicates each, corresponding tothree water temperatures (25, 28 and 31°C). A total of 225 fat snook juveniles with a mean weight of 6.45± 0.58 g were used, which were fed daily until apparent satiety. Zootechnical parameters were assessed andfeeding rates were registered for each tested temperature. Survival rates varied from 96 to 100% amongtreatments. Higher values of standard and total length, and weight gain were found in 28 and 31°C (p <0.05). With regard to final weight, final biomass, feed conversion and specific growth rate, no significantdifferences were observed (p > 0.05). Feeding rates did not differ among evaluated temperatures. Theresults show that the used temperatures did not negatively affect zootechnical performance of fat snookjuveniles.(AU)

O objetivo deste estudo foi avaliar os efeitos de diferentes temperaturas da água no desempenho zootécnico de robalo-peva. O experimento teve duração de 60 dias, foi conduzido em sistemas de recirculação de água e contou com três tratamentos de diferentes temperaturas: 25, 28 e 31ºC, com três repetições cada. Foram utilizados no total 225 juvenis de robalo-peva com peso médio de 6,45 ± 0,58 g e alimentados até saciedade aparente. Foi avaliado o desempenho zootécnico e reportadas as taxas de alimentação para cada temperatura testada. A sobrevivência dos juvenis variou de 96 a 100% entre os tratamentos. Foram observados maiores valores de comprimento-padrão, comprimento total e ganho de peso nos tratamentos de 28 e 31ºC (p < 0,05). Em relação aos parâmetros de peso final, biomassa final, conversão alimentar aparente e taxa de crescimento específico, não apresentaram diferenças significativas entre os tratamentos (p > 0,05). As taxas de alimentação também não diferiram entre as temperaturas avaliadas. Os resultados mostram que as temperaturas utilizadas não afetaram negativamente o desempenho zootécnico dos juvenis de robalo-peva.(AU)

Performance of fat snook juveniles reared at different temperatures / Desempenho de juvenis de robalo-peva cultivados em diferentes temperaturas

We aimed at evaluating the effects of different water temperatures on the zootechnicalperformance of fat snook. The experiment lasted for 60 days, which was conducted in water recirculationsystems, and was randomly designed with three treatments and three replicates each, corresponding tothree water temperatures (25, 28 and 31°C). A total of 225 fat snook juveniles with a mean weight of 6.45± 0.58 g were used, which were fed daily until apparent satiety. Zootechnical parameters were assessed andfeeding rates were registered for each tested temperature. Survival rates varied from 96 to 100% amongtreatments. Higher values of standard and total length, and weight gain were found in 28 and 31°C (p 0.05). Feeding rates did not differ among evaluated temperatures. Theresults show that the used temperatures did not negatively affect zootechnical performance of fat snookjuveniles.

O objetivo deste estudo foi avaliar os efeitos de diferentes temperaturas da água no desempenho zootécnico de robalo-peva. O experimento teve duração de 60 dias, foi conduzido em sistemas de recirculação de água e contou com três tratamentos de diferentes temperaturas: 25, 28 e 31ºC, com três repetições cada. Foram utilizados no total 225 juvenis de robalo-peva com peso médio de 6,45 ± 0,58 g e alimentados até saciedade aparente. Foi avaliado o desempenho zootécnico e reportadas as taxas de alimentação para cada temperatura testada. A sobrevivência dos juvenis variou de 96 a 100% entre os tratamentos. Foram observados maiores valores de comprimento-padrão, comprimento total e ganho de peso nos tratamentos de 28 e 31ºC (p 0,05). As taxas de alimentação também não diferiram entre as temperaturas avaliadas. Os resultados mostram que as temperaturas utilizadas não afetaram negativamente o desempenho zootécnico dos juvenis de robalo-peva.

Does intensive feeding frequency affect growth performance of common snook Centropomus undecimalis (Bloch, 1792)?

Abstract Salt water recirculation systems using automatic feeders are a new frontier for marine aquaculture. It is possible to decrease the vulnerability of the traditional fish farming in open systems and reduce wasteful feeding and discharge of effluents, as well as increase the economic returns. An experiment with common snook fingerings (4.31 ± 1.42 g and 8.4 ± 1.0 cm) was performed. Three feeding treatments were evaluated: six, twelve and eighteen feeding times per day. Each treatment had three replications. Among the three tested frequencies (fed 6, 12 and 18 times a day), the feeding frequency of 12 times per day (every two hours) showed the best values of the parameters evaluated for production performance. The final weight values, condition factor, specific growth rate and daily weight gain of the treatment 12 feeding times per day were all significantly higher than the lower and higher frequencies. Our results demonstrate that high feeding frequency is not synonymous of higher performance, but is extremely necessary to find out the best range for the target species. Besides, this relationship between feeding frequency and growth performance might change over weight range. Therefore, future studies should address higher weight ranges for comparison to our results.

Resumo Sistemas de recirculação de água salgada utilizando alimentadores automáticos são uma nova fronteira para a aquicultura marinha. Possibilitam diminuir a vulnerabilidade dos cultivos em sistemas abertos e conferir redução de desperdício de ração e lançamento de efluentes, assim como elevar o retorno econômico. Foi realizado um experimento com juvenis de Robalo-flecha (4,31 ± 1,42 g e 8,4 ± 1,0 cm). Três frequências alimentares foram avaliadas: alimentação seis vezes ao dia; doze vezes ao dia, e; dezoito vezes ao dia. Cada tratamento teve três repetições. Dentre as três frequências avaliadas a frequência alimentar de 12 vezes ao dia foi a que apresentou os melhores valores para os parâmetros zootécnicos avaliados. Os valores obtidos de peso final, fator de condição, taxa de crescimento específico e ganho de peso diário foram todos maiores para a frequência de 12 vezes ao dia do que os obtidos para as frequências maior e menor. Nossos resultados demonstram que elevadas frequências alimentares não são sinônimo de melhor desempenho produtivo, mas é extremamente importante conhecer a frequência ideal para a espécie a ser cultivada. Além disto, a relação entre frequência alimentar e crescimento pode mudar de acordo com a faixa de peso dos indivíduos. Desta forma, é extremamente importante que trabalhos futuros avaliem as frequências aqui estudadas para comparar os resultados em indivíduos maiores.

Does intensive feeding frequency affect growth performance of common snook Centropomus undecimalis (Bloch, 1792)?

Abstract Salt water recirculation systems using automatic feeders are a new frontier for marine aquaculture. It is possible to decrease the vulnerability of the traditional fish farming in open systems and reduce wasteful feeding and discharge of effluents, as well as increase the economic returns. An experiment with common snook fingerings (4.31 ± 1.42 g and 8.4 ± 1.0 cm) was performed. Three feeding treatments were evaluated: six, twelve and eighteen feeding times per day. Each treatment had three replications. Among the three tested frequencies (fed 6, 12 and 18 times a day), the feeding frequency of 12 times per day (every two hours) showed the best values of the parameters evaluated for production performance. The final weight values, condition factor, specific growth rate and daily weight gain of the treatment 12 feeding times per day were all significantly higher than the lower and higher frequencies. Our results demonstrate that high feeding frequency is not synonymous of higher performance, but is extremely necessary to find out the best range for the target species. Besides, this relationship between feeding frequency and growth performance might change over weight range. Therefore, future studies should address higher weight ranges for comparison to our results.

Resumo Sistemas de recirculação de água salgada utilizando alimentadores automáticos são uma nova fronteira para a aquicultura marinha. Possibilitam diminuir a vulnerabilidade dos cultivos em sistemas abertos e conferir redução de desperdício de ração e lançamento de efluentes, assim como elevar o retorno econômico. Foi realizado um experimento com juvenis de Robalo-flecha (4,31 ± 1,42 g e 8,4 ± 1,0 cm). Três frequências alimentares foram avaliadas: alimentação seis vezes ao dia; doze vezes ao dia, e; dezoito vezes ao dia. Cada tratamento teve três repetições. Dentre as três frequências avaliadas a frequência alimentar de 12 vezes ao dia foi a que apresentou os melhores valores para os parâmetros zootécnicos avaliados. Os valores obtidos de peso final, fator de condição, taxa de crescimento específico e ganho de peso diário foram todos maiores para a frequência de 12 vezes ao dia do que os obtidos para as frequências maior e menor. Nossos resultados demonstram que elevadas frequências alimentares não são sinônimo de melhor desempenho produtivo, mas é extremamente importante conhecer a frequência ideal para a espécie a ser cultivada. Além disto, a relação entre frequência alimentar e crescimento pode mudar de acordo com a faixa de peso dos indivíduos. Desta forma, é extremamente importante que trabalhos futuros avaliem as frequências aqui estudadas para comparar os resultados em indivíduos maiores.

Efecto de la temperatura en respuestas fisiológicas de la concha de abanico Argopecten purpuratus

Se determinó el efecto de la temperatura sobre la tasa de aclaramiento (TA), ingestión (TI) y consumo especifico de oxígeno (CEO) en individuos de Argopecten purpuratus (Lamarck, 1891) de distintos grupos de tallas. Las pruebas de TA y TI se realizaron a una concentración de Chaetoceros calcitrans de aproximadamente 1x10(6) cel.mL-1, se evaluaron dos temperaturas 17 y 22°C y se conformaron diferentes grupos de tallas promedio de 7.6 ± 0.265, 4.9 ± 0.058 y 3.7 ± 0.173 cm. En las pruebas de CEO los grupos de tallas promedio fueron 8.1 ± 0.351, 5.6 ± 0.058 y 4.3 ± 0.100 cm. Los resultados muestran un efecto significativo de la temperatura en la TA (L.h-1) y TI (cel.h-1 x 10(5)) sobre los individuos de mayor tamaño (7.6 ± 0.265 cm), observándose a 22°C un incremento promedio, respecto a 17°C, de hasta 250% para TA y 48% para TI. Además, se observó una relación directa del tamaño corporal con las TA y TI en ambas temperaturas. Se registró el efecto de la temperatura de 22°C sobre CEO en todos los grupos evaluados, con un incremento de 239.8, 165.3 y 183.4% para individuos de tallas de 8.1 ± 0.351, 5.6 ± 0.058 y 4.3 ± 0.100 respectivamente. Asimismo, los resultados muestran una relación indirecta del tamaño corporal con la CEO, en ambas temperaturas evaluadas.

The effect of temperature on the clearance rate (CR), ingestion rate (IR) and specific oxygen consumption (SOC) in individuals of Argopecten purpuratus at different size groups were determined. The CR and IR tests were performed at a concentration of approximately 1x10(6) cel.mlL-1 of Chaetoceros calcitrans, two temperatures 17 and 22 °C were evaluated and different groups of average size were formed of 7.6 ± 0.265, and 0.058 ± 4.9 3.7 ± 0.173 cm. In SOC test the average size groups were 8.1 ± 0.351, 0.058 ± 5.6 and 4.3 ± 0.100 cm. The results show a significant effect of temperature in CR (Lh-1) and IR (cel.h-1 x 10(5)) on the larger individuals (7.6 ± 0.265 cm), it was observed at 22 °C an average increase, about 17 °C, up to 250% to CR and 48% to IR. In addition, a direct relationship of body size with CR and IR in both temperatures was observed. The effect of temperature at 22 ° C on SOC in all groups was evaluated, with an increase of 239.8, 165.3 and 183.4% for size individuals of 8.1 ± 0.351, 0.058 ± 5.6 and 4.3 ± 0.100 respectively. Furthermore, in both evaluated temperatures, the results show an indirect relationship of body size with the SOC.

Simultaneous removal of C and N from fish effluents in filter reactors: Effect of recirculation ratio on the axial distribution of microbial communities.

We simultaneously removed carbon (C) and nitrogen (N) from fish effluents in compact filter reactors operating at different recirculation ratios (RRs) (2, 10 and without recirculation) to demonstrate microbial coexistence and determine the effect of the RR on the axial bacterial stratification. We also examined the global performance of anoxic, anaerobic and aerobic processes. Microbial communities (bacteria and archaea) were analyzed using 16s rRNA amplification followed by DGGE analyses. Their banding profiles were analyzed using ecological parameters and the most representative bands were sequenced. TOC removal was larger than 98% in the three reactors. The total N removal was 48% for the RR-2 reactor, whereas in the RR-10 reactor, there was no N removal due to the absence of nitrification in the final aerobic step. Coexistence and stratification of microorganisms were observed. The microbial communities were correlated with distinct biochemical processes in each reactor fraction. The RR had a large effect on the distribution of the microbial communities. When the RR increased from 2 to 10, the stratification decreased from 60 to 30%, suggesting a close relationship between reactor performance and the presence of nitrifiers. In the RR-10 reactor, the nitrifier concentration was only 4%. Thus, in combined processes, filter reactors should operate with a moderate RR to favor bacterial stratification and improve performance.

Influence of alkalinity and VFAs on the performance of an UASB reactor with recirculation for the treatment of Tequila vinasses.

The main problem linked to the stability of upflow anaerobic sludge blanket (UASB) reactors during the treatment of Tequila vinasse is the high acidity and the null alkalinity present in this effluent. This research evaluates the effect of alkalinity and volatile fatty acids (VFAs) concentration on the performance of an UASB reactor with recirculation of the effluent for removing organic matter and biogas production from Tequila vinasses. Recirculation of the effluent reduces the impact of VFAs and organic matter concentration present in the influent, inducing the stability of the reactor. The UASB reactor was operated during 235 days at organic loading rates from 2.5 to 20.0 kg m(-3) d(-1), attaining a removal efficiency of COD greater than 75% with a methane yield of 335 ml CH4 g(-1) COD at SPT, maintaining a ratio of VFAs/Alk ≤ 0.5. Therefore, an optimal ratio of VFAs/Alk was established for the system operating in stable conditions for the treatment of Tequila vinasses. Under these conditions, the alkalinity was recuperated by the system itself, without the addition of external alkalinity.

Evaluation of a recirculation system for Dorada (Brycon moorei-Steindachner 1878) larvae in the Magdalena River / Evaluación de un sistema de recirculación para la etapa de larvicultura de dorada (Brycon moorei-Steindachner 1878) del Río Magdalena / Avaliação de um sistema de recirculação para a fase de larvicultura de dourada (Brycon moorei-Steindachner 1878) de Rio Magdalenao

Recirculating aquaculture systems allow increased productivity during larval stages due to a greater control of water quality parameters. Dorada larvae (Brycon moorei) were used 12 hours post hatching (HPE) to evaluate three planting densities with four replicates per treatment and 10, 20 and 30 larvae L-1 (T1, T2 and T3, respectively). The larvae were fed with Bocachico (Prochilodus magdalenae) larvae, Artemia salina nauplii and a 40% crude protein (CP) commercial diet for 15 days. Results showed significant differences between treatments (p<0.0001) for weight gain and specific growth rate (TCE), where T1 performed better (73.24±19 mg and 14.21±5.02%, respectively); followed by T3 (67.15±24.3 mg and 13.94±7.51%) and T2 (55.67±18.33 mg and 13.36±5.75%). Survival rate was inversely related to density, with highly significant difference (p <0.0001) (39.37±6.84%, 28.00±2.80% and 14.87±6.47%) for T1, T2 and T3, respectively. Simultaneously, cannibalism was directly related to planting density. The highest profitability was obtained with T2.

Los sistemas con recirculación para acuicultura permiten el incremento de la productividad en la etapa de larvicultura, debido al mayor control de los parámetros de calidad de agua. Larvas de dorada (Brycon moorei) de 12 horas post eclosión (HPE) fueron utilizadas para evaluar tres densidades de siembra con cuatro replicas por tratamiento, 10, 20 y 30 larvas L-1 (T1, T2 y T3, respectivamente). Las larvas fueron alimentadas durante 15 días, con larvas de bocachico (Prochilodus magdalenae), nauplios de Artemia salina y una dieta comercial de 40% de proteína cruda (PC). Al final del experimento, los resultados muestran diferencias altamente significativas entre los tratamientos (p<0.0001) para ganacia de peso y tasa de crecimento específica (TCE), obteniendo un major desempeñoen T1 (73,24±19 mg y 14,21±5,02%, respectivamente); seguido por T3 (67,15±24,3 mg y 13,94±7,51%) y T2 (55,67±18,33 mg y 13,36±5,75%). La sobrevicencia se relacionó de manera inversa con la densidad con diferencia altamente significativa (p<0.0001) (39,37±6,84%; 28,00±2,80% y 14,87±6,47%) para T1, T2 y T3, respectivamente y, simultáneamente, el canibalismo fue directamente relacionado con la densidad de siembra. Por otro lado, la mayor rentabilidad fue obtenida con T2.

Os sistemas de recirculação de aquicultura permitir o aumento da produtividade na fase de larvicultura devido ao melhor controle dos parâmetros de qualidade da água. Larvas Bream (Brycon moorei) 12 horas após a eclosão (HPE) foram utilizados para avaliar três densidades de estocagem, com quatro repetições por tratamento, 10, 20 e 30 larvas L-1 (T1, T2 e T3, respectivamente). As larvas foram alimentadas durante 15 dias com bocachico larvas (Prochilodus magdalenae), náuplios Artemia salina e uma dieta comercial de proteína bruta de 40% (CP). No final da experiência, os resultados mostraram diferenças altamente significativas entre tratamentos (p < 0,0001) para o ganho de peso e taxa específica de crecimento (TEC), obtendo-se um grande desempeño en T1 (73,24±14,21 mg e 19±5,02%, respectivamente); seguido de T3 (67,15±24,3 mg e 13,94±7,51%) e T2 (55,67±18,33 mg e 13,36±5,75%). O sobrevicencia está inversamente relacionada com a densidade, com diferença altamente significativa (p<0,0001) (39,37±6,84%; 28,00%±2,80 e 14,87±6,47%) para T1 , T2 e T3, respectivamente e, simultaneamente, o canibalismo foi diretamente relacionada à densidade de estocagem. Por outro lado, o maior rendimento foi obtido com T2.

Evaluation of a rainbow trout (Oncorhynchus mikyss) culture water recirculating system / Evaluación de un sistema de recirculación de agua para levante de trucha arcoiris (Oncorhynchus mikyss)

Objective. To evaluate a water recirculation system of rainbow trout fish culture at the recirculating laboratory of the Aquaculture Engineering Production Program of the Universidad of Nariño. Materials and Methods. There were cultured 324 rainbow trout (Oncorhynchus mikyss) fries in 12 plastic tanks of 250 L capacity in a recirculation aquaculture system which treatment system was made up by a conventional sedimentation tank, a fixed bead up flow biofilter with recycled PVC tube pieces used as carrier, and a natural degassing system; the sedimentation unit effluent was pumped to a reservoir tank by a centrifugal 2 HP after passed by gravity through the biofilter and was distributed to the 12 culture units in which there were injected a constant amount of air from a blower. Results. The waste water treatment system removes 31% of the Total Suspended Solids; 9.5% of total ammonia nitrogen, and increased the dissolved oxygen to the final effluent in a 6.5%. It was calculated a biomass increase of 305% on the 75 days, the mortality percentage registered during the research period was of 4.9%. Conclusions. The wastewater treatment system maintained the physic chemical water quality parameters in the recommended values for the specie. The values of weight and size gain, food conversion, mortality and biomass production reported were between the normal values of rainbow trout fish culture in recirculating systems.

Objetivo. Evaluar un sistema de recirculación de agua para cultivo de trucha arcoiris en el laboratorio de recirculación del Programa Ingeniería en Producción Acuícola de la Universidad de Nariño. Materiales y métodos. Se cultivaron 324 alevinos de trucha arco íris (Oncorhynchus mikyss) en 12 tanques plásticos de 250 L de capacidad en un sistema de recirculación para acuacultura cuyo sistema de tratamiento estuvo constituido por un sedimentador convencional, un biofiltro de flujo ascendente con medio soporte fijo conformado por segmentos reciclados de tubos PVC, y un sistema de desgasificación natural; el efluente del sedimentador fue elevado a un tanque reservorio por medio de una bomba centrífuga de 2 HP para después pasar por gravedad a través del biofiltro y posteriormente ser distribuido a las 12 unidades de cultivo a las que de manera permanente se inyectó aire proveniente de un blówer. Resultados. El sistema de tratamiento del agua removió 31% de los sólidos suspendidos totales; 9.5% del nitrógeno amoniacal total, e incrementó el oxígeno disuelto al efluente final en un 6.5%. Se calculó un incremento de la biomasa del 345% en los 75 días, el porcentaje de mortalidad registrado durante todo el periodo de estudio fue del 4.9%. Conclusiones. El sistema de tratamiento mantuvo los parámetros físico-químicos de la calidad de agua dentro de los rangos requeridos por la especie. El incremento de peso y talla, la conversión alimenticia, la mortalidad y la producción de biomasa reportaron valores normales para producción de trucha en sistemas de recirculación.

Characterization of Mycobacterium salmoniphilum as causal agent of mycobacteriosis in Atlantic salmon, Salmo salar L., from a freshwater recirculation system.

Thirty Atlantic salmon, Salmo salar L., with low corporal condition relative to other fish present in the culture system, were sampled from a freshwater recirculation pisciculture located in Chile. The most characteristic signs and lesions were cachexia and presence of multiple greyish-white granulomas within internal organs. The external and internal lesions, along with the microscopic, histologic and biochemical findings, were consistent with mycobacteriosis. The identification of Mycobacterium salmoniphilum as the causal agent of the lesions was possible through the use of molecular analyses. This study represents the first report of Mycobacterium salmoniphilum in a freshwater recirculation system and the first case of fish mycobacteriosis described in Chile.