Growth and nitrogen uptake by Arthrospira platensiscultured in aquaculture wastewater from Nile tilapia reared in biofloc system

This study aimed to evaluate the growth of Arthrospira (Spirulina)platensiscultivated in Zarrouk culture medium and effluent from Nile tilapia (Oreochromis niloticus) reared in biofloc system. Four treatments were used: Control (100% Zarrouk), E50 (50% Zarrouk + 50% Tilapia effluent), E75 (25% Zarrouk + 75% Tilapia effluent), and E100 (100% Tilapia effluent), and the experiment lasted 10 days. Growth parameters such as maximum cell density (MCD), doubling time (DT), and growth rate (K) were daily evaluated, as well aspH and water temperature. In addition, the concentrations of total ammonia nitrogen (TAN), nitrite-N (NO2-N), and nitrate-N (NO3-N) were analyzed in order to compare nitrogen absorption. Among treatments, E50 and E75 obtained higher maximum cell densities and presented an exponential growth rate similar to the control treatment. Regarding the concentrations of nitrogen compounds, a significant reduction was observed in all treatments, with an NO3-Nuptake of 99%, followed by 80% of TAN and 90% of NO2-N. Thus, giving the results obtained, besides being able to grow in wastewater, A. platensis can also be used in bioremediation processes, confirming the potential of this species.

Growth and nitrogen uptake by Arthrospira platensiscultured in aquaculture wastewater from Nile tilapia reared in biofloc system

This study aimed to evaluate the growth of Arthrospira (Spirulina)platensiscultivated in Zarrouk culture medium and effluent from Nile tilapia (Oreochromis niloticus) reared in biofloc system. Four treatments were used: Control (100% Zarrouk), E50 (50% Zarrouk + 50% Tilapia effluent), E75 (25% Zarrouk + 75% Tilapia effluent), and E100 (100% Tilapia effluent), and the experiment lasted 10 days. Growth parameters such as maximum cell density (MCD), doubling time (DT), and growth rate (K) were daily evaluated, as well aspH and water temperature. In addition, the concentrations of total ammonia nitrogen (TAN), nitrite-N (NO2-N), and nitrate-N (NO3-N) were analyzed in order to compare nitrogen absorption. Among treatments, E50 and E75 obtained higher maximum cell densities and presented an exponential growth rate similar to the control treatment. Regarding the concentrations of nitrogen compounds, a significant reduction was observed in all treatments, with an NO3-Nuptake of 99%, followed by 80% of TAN and 90% of NO2-N. Thus, giving the results obtained, besides being able to grow in wastewater, A. platensis can also be used in bioremediation processes, confirming the potential of this species.(AU)

Recruitment of oyster in artificial collectors on the Amazon macrotidal mangrove coast / Recrutamento de ostra em coletores artificiais na costa de manguezais de macromaré amazônico

The purpose of this study was to determine the moment of the year for the oyster recruitment and define the type of collector and environmental conditions that maximize recruitment. Collections were conducted, during 12 months, on Amazon Macrotidal Mangrove at two different sites: raft (point I) and mangrove (point II). In each location three types of collectors were used (1) transparent PET bottles, (2) green PET bottles, and (3) PVC sheets, each with three replicates. Spats were counted and measured at 45-day intervals, while the environmental data were measured every two weeks. Identification of oyster species occurred by genetic testing (multiplex PCR) by randomly selecting individuals by sampling. Results indicated spat capturing was significantly influenced by the collector type, location and period of collection (P<0.05, MANOVA) with significantly higher recruitment in the PVC collector (P<0.05, Tukey test). Oyster recruitment occurred throughout the year, suggesting that these individuals reproduce during all months; however, months with less rain and greater salinity were the best for spat collection, while the rainy period with lower salinity proved to be the best for individuals growth. The location in interaction with the environmental variables, mainly salinity, has a significant effect on the recruitment rate of spat and on their size, so that point II (mangrove) had the best results for recruitment and point I (raft) provided the spats of the largest size. Genetic identification verified two native oysters species (Crassostrea gasar and Crassostrea rhizophorae) in both points (I and II).(AU)

O estudo teve como objetivo determinar o período do ano para coletar sementes de ostras, definir o tipo de coletor e as condições ambientais que maximizam o recrutamento das sementes. As coletas foram conduzidas, durante 12 meses, no manguezal amazônico de macromaré em dois locais distintos: balsa (ponto I) e manguezal (ponto II). Em cada ponto de coleta foram utilizados três tipos de coletores (1) garrafas PET transparentes, (2) garrafas PET verdes e (3) forro de PVC, com três réplicas cada. As sementes foram contadas e medidas a cada 45 dias e os dados ambientais mensurados a cada duas semanas. As espécies de ostras foram identificadas por teste genético (PCR multiplex) com indivíduos aleatoriamente selecionados por coleta. Os resultados indicaram que a captura de sementes foi influenciada significativamente pelo tipo de coletor, localização e período de coleta (P<0,05, MANOVA) com recrutamento significativamente maior no coletor de PVC (P<0,05, teste de Tukey). O recrutamento ocorreu durante todo ano, sugerindo reprodução mensal, contudo, os meses de menor pluviosidade e maior salinidade foram melhores para coletar sementes, enquanto o período chuvoso, com menor salinidade, favoreceu um crescimento superior. O local de coleta em interação com variáveis ambientais, principalmente salinidade, apresentou efeito significativo sobre a fixação e tamanho das sementes de maneira que o ponto II obteve melhores resultados de fixação e o ponto I sementes de maior tamanho. A análise genética identificou duas espécies nativas (Crassostrea gasar e Crassostrea rhizophorae) em ambos os pontos (I e II).(AU)

Influência da salinidade sobre a sobrevivência e crescimento de Crassostrea gasar / Influence of salinity on survival and growth of Crassostrea gasar

The purpose of this study was to evaluate the effect of salinity on the growth and survival of the mangrove oyster Crassostrea gasar. A laboratory trial was conducted in 10 treatments, each in triplicate, corresponding to rising values of salinity at intervals of 5 in the range of 5-50, totaling 30 experimental units. The survival and growth of the oysters were significantly influenced by salinity. A high survival of oysters in the salinity range between 10 and 45 was found. Significantly higher survival rates were obtained at salinities of 20 and 25, while at 5 there was lower survival rates. The final mean shell size and live weight of the oysters were significantly higher at a salinity of 25, while the lowest growth was registered at 5 and 50. The results suggest that the C. gasar oyster is resistant to a broad salinity range, and can be cultivated in marine regions or estuary environments that do not have salinities equal or lower than 5.(AU)

O objetivo deste trabalho foi avaliar o efeito da salinidade sobre o crescimento e a sobrevivência da ostra-do-mangue Crassostrea gasar. Em laboratório foi realizado ensaio com 10 tratamentos em triplicata, correspondentes a valores crescentes de salinidade em intervalos de 5, na faixa de 5 a 50, perfazendo 30 unidades experimentais. A sobrevivência e o crescimento das ostras foram influenciados significativamente pela salinidade. Observou-se elevada sobrevivência das ostras na faixa de salinidade entre 10 e 45. Valores significativamente superiores de sobrevivência foram obtidos nas salinidades de 20 e 25, enquanto em 5, registraram-se menores porcentagens de sobrevivência. As médias finais de tamanho de concha e de peso vivo das ostras foram significativamente superiores na salinidade de 25, enquanto que os menores valores de crescimento foram registrados em 5 e 50, em relação aos obtidos nas outras salinidades. Os resultados sugerem que a ostra C. gasar é resistente a uma ampla faixa de salinidade, podendo ser cultivada em áreas marinhas ou ambientes estuarinos que não apresentem salinidades iguais ou inferiores a 5.(AU)

Influência da salinidade sobre a sobrevivência e crescimento de Crassostrea gasar / Influence of salinity on survival and growth of Crassostrea gasar

The purpose of this study was to evaluate the effect of salinity on the growth and survival of the mangrove oyster Crassostrea gasar. A laboratory trial was conducted in 10 treatments, each in triplicate, corresponding to rising values of salinity at intervals of 5 in the range of 5-50, totaling 30 experimental units. The survival and growth of the oysters were significantly influenced by salinity. A high survival of oysters in the salinity range between 10 and 45 was found. Significantly higher survival rates were obtained at salinities of 20 and 25, while at 5 there was lower survival rates. The final mean shell size and live weight of the oysters were significantly higher at a salinity of 25, while the lowest growth was registered at 5 and 50. The results suggest that the C. gasar oyster is resistant to a broad salinity range, and can be cultivated in marine regions or estuary environments that do not have salinities equal or lower than 5.

O objetivo deste trabalho foi avaliar o efeito da salinidade sobre o crescimento e a sobrevivência da ostra-do-mangue Crassostrea gasar. Em laboratório foi realizado ensaio com 10 tratamentos em triplicata, correspondentes a valores crescentes de salinidade em intervalos de 5, na faixa de 5 a 50, perfazendo 30 unidades experimentais. A sobrevivência e o crescimento das ostras foram influenciados significativamente pela salinidade. Observou-se elevada sobrevivência das ostras na faixa de salinidade entre 10 e 45. Valores significativamente superiores de sobrevivência foram obtidos nas salinidades de 20 e 25, enquanto em 5, registraram-se menores porcentagens de sobrevivência. As médias finais de tamanho de concha e de peso vivo das ostras foram significativamente superiores na salinidade de 25, enquanto que os menores valores de crescimento foram registrados em 5 e 50, em relação aos obtidos nas outras salinidades. Os resultados sugerem que a ostra C. gasar é resistente a uma ampla faixa de salinidade, podendo ser cultivada em áreas marinhas ou ambientes estuarinos que não apresentem salinidades iguais ou inferiores a 5.