RESUMO -Este experimento foi realizado em um período de 30 dias, objetivando determinar a freqüência de arraçoamento (FA) ideal para o melhor desempenho de alevinos de lambari do rabo-amarelo (Astyanax bimaculatus). Foram utilizados 120 alevinos de lambari com peso vivo inicial de 0,34 ± 0,01 g, distribuídos em 12 tanques-rede experimentais, em um delineamento em blocos inteiramente casualizados, com quatro tratamentos e três repetições. Cada bloco correspondia a uma caixa de fibrocimento de 1000 L contendo quatro tanques-rede; cada tanque-rede com dez alevinos era uma unidade experimental. A ração possuía 30% de proteína e 3000 kcal/kg de energia digestível. O nível de arraçoamento foi de 10% do peso vivo, com pesagem de todos os peixes para correção deste nível a cada 10 dias. A variável testada foi a variação da FA (2, 4, 6 e 8 alimentações diárias). Os resultados médios das variáveis físico-químicas da água foram de 24,7 o C, 25,8 o C, 7,9 mg/L, 8,1 e 161,2 µS/cm, respectivamente, para temperaturas da manhã e tarde, oxigênio dissolvido, pH e condutividade elétrica. A biomassa por tanque dos alevinos alimentados quatro vezes ao dia foi superior aos demais tratamentos. Para o peso final e ganho de peso médios, o tratamento com quatro arraçoamentos diários foi superior ao de dois e semelhante aos demais tratamentos. A conversão alimentar não apresentou diferença e a sobrevivência diminuiu linearmente, à medida que a FA aumentou. A FA ideal para o melhor desempenho de alevinos de lambari do rabo amarelo, com a água à temperatura média de 25,5 o C, foi de quatro vezes ao dia.Palavras-chave: Astyanax bimaculatus, desempenho, freqüência de arraçoamento, lambari do rabo-amarelo, piscicultura Feeding Frequency for Yellow Tail Lambari (Astyanax bimaculatus) FingerlingsABSTRACT -This experiment was carried out, for 30 days, aiming to determine the best feeding frequency (FA) for yellow tail lambari (Astyanax bimaculatus) fingerlings. One hundred and twenty fingerlings, with initial weight of 0.34 ± 0.01 g, were allotted to 12 experimental cages, in a completely randomized block design, with four treatments and three replications. Each block corresponded to a 1000 L tank with four cages containing 10 fingerling each (experimental unit). The diet contained 30% digestible protein and 3000 kcal/kg of digestible energy. The feed allowance was 10% body weight, which was corrected each 10 days by weighing at each experimental unit. The variable tested was the number of FA (2, 4, 6, and 8 daily fed). The average for water quality parameters was of 24.7 o C, 25.8 o C, 7.9 mg/L, 8.1 and 161.2 µS/cm, respectively, for morning and afternoon temperatures, dissolved oxygen, pH, and electric conductivity. Final total weight of the fingerlings fed four times daily was higher than others. Average final weight and weight gain of fingerlings fed four times daily was higher than the ones fed twice and it was not different from the other ones. Feed conversion showed no effect and the survival rate showed a linear decrease, as FA increased....

The use of intertidal sandy beaches by fish and macrocrustaceans was studied at different temporal scales at the mouth of a tropical estuary. Samples were taken along the lunar and diel cycles in the late dry and rainy seasons. Fish assemblage (number of species, density and biomass), crustaceans and wrack biomass, showed significant interactions among all studied factors, and the combination of moon phase and diel cycle, resulting in different patterns of environmental variables (depth, water temperature and dissolved oxygen), affected habitat use by the different species. Variances in faunal community were detected between seasons, stimulated by salinity fluctuations from freshwater input during the rainy season. These differences suggest an important cycling of habitats and an increase in connectivity between adjacent habitats (estuary and coastal waters). Moreover, the results showed that this intertidal sandy beach also provides an alternative nursery and protected shallow-water area for the initial development phase of many marine and estuarine species. In addition, this intertidal habitat plays an important role in the maintenance of the ecological functioning of the estuarine-coastal ecosystem continuum.

We developed an Ecopath model in the Estuary of Sirinhaém River (SIR), a small-sized system surrounded by mangroves, subject to high impact, mainly by sugar cane industry and other farming industries in order to describe the food web structure and trophic interactions. In addition, we compared our findings with those of 20 available Ecopath estuarine models for tropical, subtropical and temperate regions, aiming to synthesize the knowledge on trophic dynamics and provide a comprehensive analysis of the structures and functioning of estuaries. Our model consisted of 25 compartments and its indicators were within the expected range for estuarine areas around the world. The average trophic transfer efficiency for the entire system was 11.8%, similar to the theoretical value of 10%. The Keystone Index and MTI (Mixed Trophic Impact) analysis indicated that the snook (Centropomus undecimalis and Centropomus parallelus) and jack (Caranx latus and Caranx hippos) are considered as key resources in the system, revealing its high impact in the food web. Both the species have a high ecological and commercial relevance, despite the unregulated fisheries. As result of the comparison of ecosystem model indicators in estuaries, differences in the ecosystem structure from the low latitude zones (tropical estuaries) to the high latitude zones (temperate system) were noticed. The structure of temperate and sub-tropical estuaries were based on high flows of detritus and export, while tropical systems have high biomass, respiration and consumption rates. Higher values of System Omnivory Index (SOI) and Overhead (SO) were observed in the tropical and subtropical estuaries, denoting a more complex food chain. Globally, none of the estuarine models were classified as fully mature ecosystems, although the tropical ecosystems were considered more mature than the subtropical and temperate ecosystems. This study is an important contribution to the trophic modeling of estuaries, Highlights ► Sirinhaém estuary, Northeast Brazil, is an immature and resilient ecosystem. ► The jack and, mainly, snook were key species in the Estuary of Sirinhaém River. ► Tropical estuaries were based in high biomass, respiration and consumption rates. ► The System Overhead Index was higher in tropical estuaries than in the other systems. ► TPP/TR was lower in tropical estuaries than in the other systems.

RESUMO -Este trabalho foi realizado com o objetivo de determinar o nível ideal de arraçoamento, em porcentagem do peso vivo, para alevinos de lambari-do-rabo-amarelo (Astyanax bimaculatus). Foram utilizados 240 alevinos de lambari com peso vivo de 0,52 ± 0,05 g, distribuídos em 24 hapas, em um delineamento em blocos inteiramente casualizados, com seis tratamentos e quatro repetições. Cada bloco correspondeu a uma caixa de fibrocimento com capacidade para 1.000 L, com seis hapas, cada uma com 10 alevinos. Cada hapa foi considerada uma unidade experimental. Os tratamentos consistiram dos níveis de arraçoamento de 1, 4, 7, 10, 13 e 16% do peso vivo dos animais em ração (30% proteína digestível e 3.000 kcal/kg de energia digestível). Os parâmetros físico-químicos médios aferidos da água foram 24,5 o C; 25,1 o C; 8,4 mg/L; 7,9 e 160, 9 μS/cm, respectivamente, para temperaturas matutina e vespertina, oxigênio dissolvido, pH e condutividade. Os resultados indicam que o melhor nível de arraçoamento para alevinos de lambari do rabo amarelo à temperatura média de 25 o C é de 11,5% do peso vivo.Palavras-chave: alimentação, Astyanax bimaculatus, desempenho, lambari, piscicultura Feeding Level for Yellow Tail Lambari (Astyanax bimaculatus) FingerlingsABSTRACT -The current work aimed to evaluate the ideal diet level for yellow tail lambari (Astyanax bimaculatus) fingerlings on body weight percentage. Two hundred and forty fingerlings averaging initial weight of 0.52 ± 0.05 g were allotted to 24 hapas according to a completely randomized blocks with six treatments and four replicates. A 1000 L-tank with 6 hapas was considered the block. A hapa with 10 fingerlings was considered the experimental unit. The treatments consisted of increasing feeding levels: 1, 4, 7 10, 13, and 16% of body weight (30% of digestible protein and 3,000 kcal/kg of digestible energy). The observed water parameters were as follows: 24.5 o C, 25.1 o C, 8.4 mg/L, 7.9 e 160.9 μS/cm, respectively, for morning and afternoon temperature, dissolved oxygen, pH, and electric conductivity. The results showed that the best level of feeding for yellow tail lambari fingerlings on average water temperature of 25 o C was of 11.5% of body weight. IntroduçãoA piscicultura é um ramo da zootecnia atualmente em evidência no Brasil, fato relacionado à grande aptidão do país para este tipo de atividade, do clima adequado e da grande disponibilidade de água, acrescido pela ótima qualidade nutricional desse peixe. Entre as espécies mais cultivadas, estão as de origem exótica, como a tilápia e as carpas. Entretanto, dentro da ampla diversidade da fauna aquática brasileira, são encontradas espécies que se adequam perfeitamente ao cultivo, como o pacu, o tambaqui, o piavuçu, entre outros.O lambari-do-rabo-amarelo (Astyanax bimaculatus) é uma espécie nativa, de pequeno porte, que aceita alimentação artificial com bastante facilidade e apresenta bom potencial para a aquicultura, pois é bastante apreciado como petisco, além de ser muito requisitado como isca para a pesca esportiva....

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