Distribution and Accumulation of Trace Elements in Organs of Juvenile Fishes from a Freshwater System (Paraná River, South America).

The concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn (TE) in four juvenile fishes (Acestrorhynchus pantaneiro, Salminus brasiliensis, Brycon orbignyanus, and Megaleporinus obtusidens) and associated sediment water from the Lower Paraná River were measured. For muscle, gills, and liver fishes, the TE accumulation in the muscle, gills, and liver was evaluated. The TE concentration was measured by quadrupolar inductively coupled plasma mass spectrometry (Q-ICP-MS). Cadmium (0.25 ± 0.07 µg L-1), Cu (3.00 ± 1.44 µg L-1), Fe (612 ± 69 µg L-1), and Pb (1.92 ± 1.20 µg L-1) in water and As (4.1-6.9 µg g-1), Cr (20.1-31.4 µg g-1), Cu (10.7-19.2 µg g-1), Mn (351.3-482.2 µg g-1), and Ni (24.5 ± 10.9 µg g-1) in sediments exceeded the guide values for the conservation of aquatic life. In general, muscle of omnivorous species (B. orbignyanus and M. obtusidens) showed higher values of elements than those of carnivorous species (A. pantaneiro and S. brasiliensis). However, TE concentrations varied with fish species and organs. Independently of the examined species, the highest concentrations of Cr and Pb were in the muscle and gills, respectively. Cadmium, Cu, and Fe concentrations were higher in the liver than in gills and muscle in all four fish species. These results were consistent with the tissue selectivity index analyzed. For the four species, major essential elements showed the highest accumulation. However, the accumulation of toxic elements in omnivorous fish was higher than in carnivorous fish. The individual pollution load index indicated that sediment was very polluted with As and Pb, but based on the combined ecological indexes, low elemental sediment pollution in the Espinillo Lake was revealed.

Metals in fish of different trophic levels in the area of influence of the AHE Foz do Chapecó reservoir, Brazil.

In regions where there is intense polluting activity, a greater availability of metals in water impounded by dams increases the availability and contamination of the fauna and flora. Thus, we assessed the accumulation of metals in muscle and gills of fish of different trophic levels in the area of influence of Foz do Chapecó hydroelectric plant on the Uruguai river. We analyzed the metals Pb, Cd, Cu, Cr, Mn, Zn, and Fe in Hypostomus isbrueckeri (cascudo), Pimelodus maculatus (mandi), and Salminus brasiliensis (dourado). We collected specimens from both upstream and downstream of the reservoir in February and March 2014. We also measured the allometric condition factor of the fish to determine their physiological status. Physical and chemical variables of the water were measured to determine the influence of these abiotic variables on the bioavailability of metals and on the condition factor of the fish. Gills had a higher concentration of metals than muscle. Hypostomus isbrueckeri and Pimelodus maculatus possessed high concentrations of metals, indicating greater bioaccumulation in benthic species. Only chromium in muscle varied significantly between upstream and downstream, with higher concentrations in H. isbrueckeri and P. maculatus upstream. Chromium contamination, however, did not change the condition factor, which did not vary between upstream and downstream for any of the studied species. We found no influence of abiotic variables of the water on the bioavailability of the metals in the environment. Although the data do not indicate trophic magnification, the different species react differently to environmental changes and their trophic plasticity makes it difficult to assign them to specific guilds.

Wide reproductive period of a long-distance migratory fish in a subtropical river, Brazil

Salminus brasiliensis is a potamodromous fish species that occurs in southern South American rivers. In spite of its ecological and economic relevance, information regarding the reproductive biology of S. brasiliensis is still scarce. This study used data from 18 years of continuous sampling in the Upper Uruguay River Basin, analyzing 718 adult fish (307 males, 243 females, 168 undefined) captured at different months of the year. The results showed that the reproductive timing for S. brasiliensis is wide in the Upper Uruguay River, with the occurrence of mature fish between the month of August and March and spawned individuals between July and May of the next year. These results were sustained by the increase of gonadal somatic relationship (GSR) from August. The reproductive timing of S. brasiliensis in the Upper Uruguay River may start between the middle winter and early spring (from late July to late September), and may extend until the late summer and middle fall (from the middle February to early May). These findings contribute to information on the general biology of S. brasiliensis and provide valuable knowledge to management programs and to conservation efforts of this fisheries resource.(AU)

Salminus brasiliensis é uma espécie potamodroma que ocorre em rios da América do Sul. Apesar de sua importância ecológica e econômica, informações sobre a biologia reprodutiva de S. brasiliensis ainda são escassas. O presente estudo utilizou dados de 18 anos de amostragens contínuas na bacia do alto rio Uruguai, analisando 718 peixes adultos (307 machos, 243 fêmeas, 168 indefinidos) capturados em diferentes meses do ano. Os resultados mostraram que o período reprodutivo de S. brasiliensis é amplo na bacia do alto rio Uruguai, com a ocorrência de peixes maduros entre agosto e março, e de peixes desovados entre os meses de julho e maio do ano seguinte. A relação gonadossomática reforça essa observação, pois mostra um aumento a partir de agosto. O período reprodutivo de S. brasiliensis no alto rio Uruguai pode iniciar entre meados do inverno e início da primavera (entre final de julho e final de setembro), podendo se estender até o final do verão e meados do outono (entre meados de fevereiro e início de maio). Essas descobertas contribuem com informações sobre a biologia geral de S. brasiliensis e são relevantes para programas de gestão e para esforços de conservação desse recurso pesqueiro.(AU)

Appetite regulating factors in dourado, Salminus brasiliensis: cDNA cloning and effects of fasting and feeding on gene expression.

The dourado, Salminus brasiliensis (Cuvier, 1816) is a freshwater piscivorous Characin native to South American rivers. Owing to the high quality of its flesh and its fast growth, it is the object of both capture fisheries and fish farming. However, very little is known about the endocrine regulation of feeding and metabolism of dourado. In this study, cDNAs for orexin, CART and CCK were isolated in dourado, and their mRNA tissue distributions examined. In order to assess the role of these peptides in the regulation of feeding of dourado, the effects of fasting and feeding on mRNA expression levels of orexin, CART and CCK in the brain as well as CCK in the intestine were assessed. Whereas orexin and CCK have widespread mRNA distributions in the brain and peripheral organs, CART seems to be mostly limited to the brain. Orexin brain expression increased with fasting and displayed periprandial changes, suggesting it is involved in both long- and short-term regulation of feeding and appetite. CART and CCK hypothalamic expressions were not affected by fasting, but displayed periprandial changes with post-feeding decreases, suggesting roles in short-term satiation. CCK expression in the anterior intestine was not affected by fasting and did not display periprandial changes. Overall, our results suggest that orexin, CART and CCK are involved in the physiology of feeding of dourado.

Genetic variability of broodstocks of restocking programs in Brazil / Variabilidad genética de lotes de reproductores de programas de repoblación en Brasil

Objective. The aim of this study was evaluate the genetic diversity of the following broodstocks: piapara (Leporinus elongatus), dourado (Salminus brasiliensis), jundiá (Rhamdia quelen) and cachara (Pseudoplatystoma fasciatum) already useful for restocking programs in the Paranapanema, Iguaçu and Paraná Brazilian Rivers. Materials and methods. Samples from the caudal fin of 122 fish were analyzed. DNA was extracted by NaCl protocol. PCR products were separated by a horizontal agarose gel electrophoresis. The fragments were visualized by staining with ethidium bromide. Results. The amplification of 25 primers generated different fragments in studied species that allowed characterizing 440 fragments of 100-2900 bp. High percentage of polymorphic fragments (66.67 to 86.29), Shannon index (0.365 to 0.486) and genetic diversity of Nei (0.248 to 0.331) were detected. Conclusions. The level of genetic variability in the broodstocks was adequate for allowing their use in restocking programs in the studied Rivers. However, periodical monitoring studies of genetic variability in these stocks, the mating system, reproductive system and general management must be made to guarantee the preservation of wild populations.

Objetivo. El objetivo de este estudio fue evaluar la diversidad genética de los siguientes lotes de reproductores: piapara (Leporinus elongatus), dourado (Salminus brasiliensis), jundiá (Rhamdia quelen) y cachara (Pseudoplatystoma fasciatum) utilizados para programas de repoblación en los ríos brasileños Paranapanema, Iguaçu y Paraná. Materiales y métodos. Muestras de aleta caudal de 122 peces fueron analizadas. El ADN fue extraído por el protocolo de NaCl. Los productos de PCR fueron separados por electroforesis horizontal en gel de agarosa. Los fragmentos fueron visualizados por marcación con bromuro de etidio. Resultados. La amplificación de los 25 iniciadores produjo diferentes fragmentos en las especies estudiadas que permitieron caracterizar 440 fragmentos de 100 a 2900 pb. Fueron detectados un alto porcentaje de fragmentos polimórficos (66.67 a 86.29), de índice de Shannon (0.365 a 0.486) y de diversidad genética de Nei (0.248 a 0.331). Conclusiones. El nivel de variabilidad genética en los lotes de reproductores fue adecuado para su utilización en programas de repoblación en los ríos estudiados. Sin embargo, estudios de monitoreo periódico de la variabilidad genética en esos lotes, del sistema de cruzamiento, del sistema reproductivo y del manejo general deben ser realizados para garantizar la preservación de las populaciones naturales.

Mate extract on lipid and color changes of dourado fillets during frozen storage / Extrato de mate sobre alterações lipídicas e de cor de filés de dourado durante o armazenamento congelado

This study aimed to evaluate whether mate (Ilex paraguariensis A. St. Hil) extract would change lipid and color stability of dourado (Salminus brasiliensis) fillets during frozen storage. Fish fillets were dipped (1 min) in distilled water (control) or in aqueous extract of mate (0.1g mL-1, w/v) and were stored at -7°C for up to 12 months. Conjugated dienes (CD) increased in control fillets after 6 months of storage and then decreased, whereas thiobarbituric acid reactive substances (TBARS) value increased along the whole experimental period. Mate treatment reduced CD and TBARS values of fillets. Dourado fillets tended to yellow along the whole experimental period (average H*= 72.55) Although the mate treatment had increased the yellowness of fillets at the start of storage, this treatment reduced the increase in luminosity (L*) and in yellowness (H*) triggered by frozen storage. Results indicate that mate extract inhibits lipid oxidation and some color changes caused by the frozen storage of fish fillets.

Foi avaliado o efeito do extrato de mate (Ilex paraguariensis A. St. Hil) sobre as alterações lipídicas e de cor de filés de dourado (Salminus brasiliensis) durante o armazenamento congelado. Os filés foram mergulhados (1 min) em água destilada (controle) ou em extrato aquoso de mate (0,1g mL-1, p/v) e armazenados a -7°C por 12 meses. Os dienos conjugados (DC) aumentaram nos filés controle após 6 meses de armazenamento e então diminuíram, enquanto os valores de substâncias reativas ao ácido tiobarbitúrico (TBARS) aumentaram ao longo de todo período experimental. O extrato de mate reduziu os valores de DC e TBARS dos filés. Os filés de dourado tenderam ao amarelo ao longo de todo o período experimental (média do H*=72.55). Ainda que o tratamento com mate tenha aumentado a intensidade de amarelo dos filés no início da armazenagem, esse tratamento reduziu o aumento da luminosidade (L*) e da intensidade de amarelo (H*), promovidos pelo armazenamento congelado. Os resultados indicam que o extrato de mate inibe a oxidação lipídica e algumas alterações de cor decorrentes do congelamento de filés de pescado.

Sensibilidade dos espermatozoides de dourado (Salminus brasiliensis) a diferentes soluções crioprotetoras / Sensitivity of dourado (Salminus brasiliensis) spermatozoa to different cryoprotectant solutions

Em três experimentos, avaliou-se a sensibilidade dos espermatozoides de dourado (Salminus brasiliensis) a diferentes soluções crioprotetoras. No experimento 1, o sêmen foi diluído, 1:10, em 12 soluções (quatro diluidores x três crioprotetores - dimetilsulfóxido (DMSO), metilglicol ou glicerol). Metade de cada amostra foi resfriada por uma hora e a outra, criopreservada. A motilidade espermática foi avaliada imediatamente após a diluição e após o resfriamento em todas as amostras e, após o descongelamento, apenas nas amostras criopreservadas em DMSO. No experimento 2, o sêmen foi diluído, 1:5, em cinco soluções contendo DMSO e resfriado, criopreservado e avaliado como no experimento 1. No experimento 3, o sêmen foi diluído, 1:5, em quatro soluções contendo DMSO e criopreservado e avaliado quanto à motilidade e à fertilidade. Quando o sêmen foi diluído 1:10, observou-se motilidade acima de 58 por cento em todas as amostras resfriadas em DMSO e em NaCl-tris-metilglicol. Baixa motilidade foi observada nas amostras resfriadas nas outras combinações com metilglicol (5-32 por cento) ou glicerol (0-8 por cento) e naquelas criopreservadas (16-20 por cento). Todas as amostras diluídas 1:5 apresentaram motilidade de 65-72 por cento após o resfriamento e de 45-66 por cento após o descongelamento (experimentos 2 e 3). As taxas de eclosão produzidas com sêmen criopreservado, entretanto, foram baixas (17-23 por cento) em relação ao sêmen fresco (60 por cento).

The sensitivity of dourado (Salminus brasiliensis) spermatozoa to different cryoprotectant solutions was evaluated in three experiments. In experiment 1, semen was diluted, 1:10, in 12 solutions (four extenders x three cryoprotectants - dimethylsulphoxide (DMSO), methyglycol, or glycerol). Half of each sample was refrigerated for one hour while the other half was cryopreserved. Sperm motility was immediately assessed after dilution and after refrigeration in all samples, and after thawing in those cryopreserved in DMSO. In experiment 2, semen was diluted, 1:5, in five solutions containing DMSO, refrigerated, cryopreserved, and analyzed as in experiment 1. In experiment 3, semen was diluted, 1:5, in five solutions containing DMSO, cryopreserved and evaluated for motility and fertility. When semen was diluted 1:10, motility higher than 58 percent was observed in all samples refrigerated in DMSO and in NaCl-tris-methylglycol. Low motility was observed in samples refrigerated in the other combinations of methylglycol (5-32 percent) or glycerol (0-8 percent) and in those cryopreserved (16-20 percent). All samples diluted 1:5 yielded motility of 65-72 percent after refrigeration, and 45-66 percent after thawing (experiments 2 and 3). The hatching rates produced with cryopreserved semen, however, were lower (17-23 percent) compared to fresh semen (60 percent).

Statistical distribution models for migratory fish in Jacuí basin, South Brazil

The aim of the present study was to identify the distribution patterns of migratory fishes in the Jacuí river basin (Rio Grande do Sul, South Brazil), proposing a statistical model of presumed distribution based on geomorphologic environmental data. Through maps of occurrence probability, we hope to contribute to decisions regarding basin environmental management. The analyzed species were: Salminus brasiliensis (dourado), Leporinus obtusidens (piava), Prochilodus lineatus (grumatã) and Pimelodus pintado (pintado). Samples were made through interviews with fishermen and local inhabitants, covering the main channel and tributaries of the rivers Jacuí, Taquari-Antas, Vacacaí, Vacacaí-Mirim, Pardo, Pardinho, Sinos, and Caí. The sampling program resulted in 204 interviews, being 187 considered as valid in 155 different sampling points. The probability of migratory fish occurrence was adjusted through the LOGIT routine of the Idrisi Andes Software: P = e(b0 + b1 . altitude + b2 . basin area) . (1 + e(b0 + b1 . altitude + b2 . basin area))-1, where P is the occurrence probability of the species (0-1) and b0, b1 and b2 are the equation parameters. Model accuracy, for estimating presence, ranged from 82 percent to 93 percent. Pimelodus pintado was cited to occur in 121 points among the 155 sampled (78.06 percent), Prochilodus lineatus in 72 (46.45 percent), L. obtusidens in 62 (40.00 percent) and S. brasiliensis in 58 (37.42 percent). Equation parameters were estimated (± standard error) as follow: S. brasiliensis: b0 = -2.8762 ± 0.2597; b1 = 1.3028 ± 0.0332; b2 = 1.1487 ± 0.0301; L. obtusidens: b0 = -0.8364 ± 0.2213; b1 = -1.5564 ± 0.0462; b2 = 0.9947 ± 0.0206; Prochilodus lineatus: b0= 0; b1= -1.3067 ± 0.0544; b2= 0.8128 ± 0.0177; Pimelodus pintado: b0= -0.9487 ± 0.3688; b1= -0.8269 ± 0.0496; b2= 0.9255 ± 0.0304.(AU)

O objetivo do presente estudo foi identificar o padrão de distribuição de peixes migradores da bacia hidrográfica do rio Jacuí (Rio Grande do Sul, Sul do Brasil), propondo um modelo matemático de distribuição presumida baseado em parâmetros ambientais geomorfológicos. Através de mapas de probabilidade de ocorrência, espera-se contribuir para a tomada de decisões relacionadas ao gerenciamento desta bacia hidrográfica. As espécies analisadas foram: Salminus brasiliensis (dourado), Leporinus obtusidens (piava), Prochilodus lineatus (grumatã) e Pimelodus pintado (pintado). As amostras foram obtidas a partir de entrevistas com pescadores e moradores locais, percorrendo-se a calha principal dos rios Jacuí, Taquari-Antas, Vacacaí, Vacacaí-Mirim, Pardo, Pardinho, Sinos e Caí. O programa de amostragens resultou em 204 entrevistas, sendo 187 consideradas como válidas em 155 pontos diferenciados. A probabilidade de ocorrência de peixes migradores foi ajustada utilizando-se a rotina LOGIT do software Idrisi Andes: P = e(b0 + b1 . altitude + b2 . área de bacia) . (1 + e(b0 + b1 . altitude + b2 . área de bacia))-1; onde P é a probabilidade de ocorrência da espécie (0-1) e b0, b1 e b2 são os parâmetros da equação. Pimelodus pintado foi citado como presente em 121 pontos dentre os 155 amostrados (78.06 por cento), Prochilodus lineatus em 72 (46.45 por cento), L. obtusidens em 62 (40.00 por cento), e S. brasiliensis em 58 pontos (37.42 por cento). A precisão do modelo, para a presença estimada, ficou entre 82 por cento e 93 por cento. Os parâmetros estimados da equação são descritos a seguir: S. brasiliensis: b0= -2.8762 ± 0.2597; b1= -1.3028 ± 0.0332; b2= 1.1487 ± 0.0301; L. obtusidens: b0 = -0.8364 ± 0.2213; b1 = -1.5564 ± 0.0462; b2 = 0.9947 ± 0.0206; Prochilodus lineatus: b0 = 0; b1 = -1.3067 ± 0.0544; b2 = 0.8128 ± 0.0177; Pimelodus pintado: b0 = -0.9487 ± 0.3688; b1 = -0.8269 ± ...(AU)

Stress in Salminus brasiliensis fingerlings due to different densities and times of transportation / Estresse em alevinos de dourado (Salminus brasiliensis) em diferentes densidades e tempos de transporte

The stress in dorado fingerlings (Salminus brasiliensis) caused by transportation at densities of 5, 10, and 15g/l after 4, 8, and 12h was evaluated by the concentration of tissue cortisol measured by ELISA. The conditions of transportation were simulated on an orbital table shaker with horizontal movements, inside 15 litres plastic bags filled with 4 litres of water and pure oxygen. Cortisol concentrations increased in all densities after 4h of transportation converging to a common concentration at the end of the tested times. Electrical conductivity of water increased with density and transportation time. The transportation caused stress on fish, but the increase on density and in times of transportation did not cause mortality to fingerlings. The transportation of S. brasiliensis fingerlings can be done without mortality or apparent injuries to animals until the maximum analyzed density of 15g/l and up to 12h.

O estresse em alevinos de dourado (Salminus brasiliensis) causado pelo transporte nas densidades 5, 10 e 15g/l após 4, 8 e 12h, foi avaliado por meio dos níveis de cortisol tecidual quantificado por ELISA. O transporte foi simulado em uma mesa agitadora com movimento orbital, em sacos plásticos de 15 litros, contendo 4 litros de água e oxigênio puro. As concentrações de cortisol aumentaram em todas as densidades após 4h de transporte e convergiram para uma mesma concentração ao final dos tempos de transporte. A condutividade elétrica da água aumentou com a densidade e com os tempos de transporte. O transporte causou estresse aos peixes, mas o aumento da densidade e do tempo de transporte não causou mortalidade nos alevinos. O transporte de alevinos de S. brasiliensis pode ser realizado até a densidade máxima avaliada de 15g/l e o tempo máximo de 12h sem que haja mortalidade ou danos aparentes aos animais.

Induction and recovery time for dourados Salminus brasiliensis (Cuvier, 1816) submitted to different concentrations of clove oil Eugenia sp - DOI: 10.4025/actascibiolsci.v30i3.485 / Tempo de indução e de recuperação de dourados Salminus brasiliensis (Cuvier, 1816), submetidos a diferentes concentrações de óleo de cravo Eugenia sp. - DOI: 10.4025/actascibiolsci.v30i3.485

The present study evaluated five different concentrations (20, 30, 40, 50 and 60 mg L-1) of clove oil as an anesthetic for dourado juveniles, using induction and recovery time to determine the ideal concentration. Significant difference (p 0.05) was observed among 20, 30, 40 and 60 mg L-1 levels of clove oil. However, 50 mg L-1 concentration did not show significant difference in comparison to 40 and 60 mg L-1. Regarding recovery time, the shortest time was verified in the concentration of 20 mg L-1. Clove oil is effective and safe as an anesthetic for dourado juveniles in levels between 40 and 60 mg L-1.

O presente estudo avaliou o óleo de cravo como anestésico para juvenis de dourado em cinco diferentes concentrações (20, 30, 40, 50 e 60 mg L-¹), utilizando como critério para determinação da concentração ideal os tempos de indução e de recuperação ao efeito do anestésico. Em relação aos tempos de indução, verificou-se diferença significativa (p 0,05) entre as concentrações de 20, 30, 40 e 60 mg L-¹ de óleo de cravo. No entanto, a concentração de 50 mg L-¹ não diferiu estatisticamente dos níveis de 40 e 60 mg L-¹. Quanto à recuperação, o menor tempo foi verificado para a concentração de 20 mg L-¹. O óleo de cravo é eficiente e seguro como anestésico para juvenis de dourado, quando utilizado entre 40 a 60 mg L-¹.

Salminus franciscanus, a new species from the rio São Francisco basin, Brazil (Ostariophysi: Characiformes: Characidae)

Salminus franciscanus, the large-sized dourado from the rio São Francisco basin, Brazil, is described. The new species was actually known ichthyologically since at least Valenciennes (in Cuvier & Valenciennes, 1850) but it was never properly identified. Salminus franciscanus can be diagnosed from its congeners by the combination of the presence of an enlarged second tooth in the outer series of the dentary considerably larger than the remaining teeth, the absence of a dark post-orbital stripe, scale counts (68-82 lateral line scales, 11-14 horizontal series of scales between dorsal-fin origin and lateral line, and 6-8 horizontal series of scales between the lateral line and the pelvic-fin insertion), and a developed extension of the middle rays of the caudal fin. The historical taxonomy of the species is discussed.

Salminus franciscanus, o dourado de grande porte da bacia do rio São Francisco, Brasil, é descrito. Esta espécie, embora conhecida ictiologicamente desde meados do século XIX (Valenciennes, em Cuvier & Valenciennes, 1850), nunca foi identificada de forma correta. Salminus franciscanus pode ser distinguida de suas congêneres pela combinação dos seguintes caracteres: presença de um dente da série externa do dentário consideravelmente maior que os demais dentes, ausência de uma faixa pós-orbital escura, contagens intermediárias de escamas (68-82 escamas na linha lateral, 11-14 séries de escamas horizontais entre a origem da nadadeira dorsal e a linha lateral e 6-8 séries de escamas horizontais entre a linha lateral e a inserção da nadadeira pélvica) e um prolongamento mediano da nadadeira caudal bem desenvolvido. Um sumário sobre as discussões taxonômicas acerca da espécie presentes na literatura é apresentado.

Growth and survival of dorado Salminus brasiliensis (Pisces, Characidae) post-larvae cultivated with different types of food and photoperiods

The effect of food and photoperiod on dorado (Salminus brasiliensis) post-larvae growth and survival was investigated using the following treatments: LD (Light: Dark) 24:0 + Artemia nauplii (A), LD 24:0 + fish prey (F), LD 14:10 + A, LD 14:10 + F, LD 0:24 +A and LD 0:24 + F. Prochilodus lineatus larvae were used as fish prey. Higher survival rates were registered in fish prey treatments (P<0.05) and were not influenced by photoperiod whereas in Artemia treatments, the survival was very low, but directly proportional to light increase (P<0.05). The better growth in LD 0:24 was related to a safe-energy strategy that reduced energy consumption whereas in LD 24:0, the higher energy consumption reduced the growth. In intermediate photoperiod, the post-larvae did not define a strategy to capture preys, using alternatively the static safe-energy and the swimming consuming energy, which caused higher heterogeneity in growth.

O efeito da alimentação e do fotoperíodo sobre o crescimento e a sobrevivência de pós-larvas de dourado (Salminus brasiliensis) foi investigado utilizando-se os seguintes tratamentos: LE (Luz: Escuro) 24:0 + náuplios de Artemia (A), LE 24:0 + larva forrageira (L), LE 14:10 + A, LE 14:10 + L, LE 0:24 +A e LE 0:24 + L. Larvas de Prochilodus lineatus foram utilizadas como larva forrageira. Taxas de sobrevivência mais elevadas foram registradas nos tratamentos que utilizaram larvas forrageiras (P<0,05), que não foram influenciados pelo fotoperíodo, enquanto nos tratamentos com Artemia a sobrevivência foi muito reduzida, mas diretamente proporcional ao aumento da disponibilidade de iluminação (P<0,05). O melhor crescimento em LE 0:24 esteve relacionado ao uso de uma estratégia de baixo consumo energético enquanto em LE 24:0 o maior consumo de energia produziu menor crescimento. No fotoperíodo intermediário as pós-larvas não definiram uma estratégia única para capturar as presas, utilizando alternadamente a estratégia estática de baixo consumo de energia e a estratégia natatória, associada a um maior consumo energético, que causou maior heterogeneidade no crescimento.