-This study aimed to evaluate the productivity, growth performance and economic feasibility of polyculture of Nile tilapia Oreochromis niloticus and shrimp Litopenaeus vannamei at different stocking densities. Feed was provided based on fish requirements. The experiment was conducted at the Aquaculture facility of the Universidade Federal Rural do SemiÁrido -UFERSA, in a completely randomized design with five treatments and four replicates each. Treatments consisted of a tilapia monoculture with 2 tilapias.m -2 ; and polyculture with 2 tilapias.m -2 and L. vannamei at four different densities (3, 6, 9 and 12 shrimps.m -2 ). The initial individual biomass for fish and shrimp were 1.23±0.12 g and 0.133±0.009 g, respectively.Water quality parameters, temperature, dissolved oxygen, pH and transparency were monitored. The experiment lasted 120 days and biomass gain was evaluated every two weeks. Final biomass, survival and feed conversion rates were calculated at the end of the experiment. The economic analysis showed that polyculture systems at stocking densities of nine and twelve shrimps.m -2 resulted in higher gross revenue and operational profits of 120.9% and 97.5% respectively, with mean gross return significantly higher than the monoculture. The O. niloticus and L. vannamei polyculture in oligohaline water was shown to be technically and economically feasible. These two species can be cultured together, without competing for the same resources, because they have different trophic niche, thus increasing productivity and economic returns for the farmers.
The aim of this study was to assess the feasibility of integrated multi-trophic culture of Nile tilapia (Oreochromis niloticus) and Amazon River prawn (Macrobrachium amazonicum) in brackish water by evaluating its limnological characteristics and economic performance. The experiment was completely randomized with four treatments and four repetitions: control treatment with Nile tilapia only, stocked with 2 tilapias/m² (P2C0) and three integrated multi-trophic culture treatments stocked with 2 tilapias/m² and prawns at densities of 4, 8 and 16 prawns/m² (P2C04, P2C08 and P2C16, respectively). The limnological variables of temperature, pH, dissolved oxygen, turbidity, ammonia, orthophosphate and chlorophyll "a" were evaluated and throughout the experiment remained within the limits recommended for culture. The experiment lasted 150 days with monthly animal sampling. No significant differences were observed for total fish biomass or for fish and prawn total survival rates. However, prawn individual weight decreased as stocking density increased. Gross revenue was not significantly different between treatments, as well as profitability. The profitability was 40.1% (P2C0), 36.7% (P2C04), 41.2% (P2C08) and 50.1% (P2C16). It is concluded that although feasible from the view point of husbandry, the integrated multi-tropic culture of M. amazonicum and O. niloticus did not influence significantly profitability compared to the monoculture system.
This study aimed to determining the manner in which salinity influenced the growth of the macroalgae Gracilaria birdiae, with the objective of identifying its tolerance limits to this abiotic variable. The specimens were submitted to nutrient-enriched water of varying salinities (0, 10, 20, 30, 40, 50, and 60 ppt) for a 30-day period. Initially, under extreme salinity conditions (0 and 60 ppt) the growth of the G. birdiae suffered a negative impact. The macroalgae biomass exposed to 0 and 10 ppt salinities showed a reduction from day six until the experiment was completed. The macroalgae biomass exposed to salinities 20, 30, 40, and 50 ppt showed an increase, with no significant differences between the four treatments. This suggested that this salinity range was comfortable for this species to develop. We concluded that salinity is a crucial parameter which controls the growth of the G. birdiae. This seaweed was negatively influenced when exposed to values equal to or below 10 ppt and equal to 60 ppt, demonstrating good tolerance to salinities of 20, 30, 40 and 50 ppt.
O crescente desenvolvimento da carcinicultura no Brasil e no Rio Grande do Norte, tem ampliado o mercado de trabalho, contudo, os trabalhadores são expostos a várias substancias, que podem comprometer a sua saúde. Dessa forma, esse estudo objetivou identificar as condições do ambiente de trabalho de uma fazenda de criação de camarão, verificando os riscos, acidentes do trabalho e doenças ocupacionais. Foi realizado uma avaliação no âmbito de segurança e saúde em uma empresa de criação de camarão de Mossoró, Rio Grande do Norte. Foram utilizadas diversas normas regulamentadoras da Portaria 3.214/78 do Ministério do Trabalho, baseado na segurança, saúde e meio ambiente. Foram entrevistados 40 funcionários, dentre eles, 70% demonstraram ser conscientes com relação ao uso de equipamentos de proteção individual. Contudo, registrou-se uma ocorrência de acidentes com 42,50%, sendo a causa maior por cortes e feridas (65,21%). A empresa Aquadelta Agroindustrial, cumpre com todas as normas vigentes. Entretanto, os riscos ambientais são existentes, registrando maior ocorrência os riscos mecânicos, os quais não impossibilitam os funcionários a trabalhar e com menor ocorrência, os riscos químicos, considerados de natureza grave.
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