ResumenEl desarrollo temprano de las larvas de peces es un proceso altamente dinámico y estudiarlo proporciona información importante sobre su desarrollo ontogénico, su crecimiento bioenergético, su comportamiento, las características taxonómicas para la identificación en entornos naturales, la identificación de las zonas de desove y la vigilancia de la población. Los primeros años de vida de Prochilodus argenteus y Prochilodus costatus fueron estudiados desde la eclosión hasta la completa absorción de la yema, con el fin de proporcionar conocimiento sobre los caracteres taxonómicos y el crecimiento y comportamiento, lo cual puede ser aplicado al desarrollo de la cría de larvas. Las larvas fueron obtenidas junto a la Estación de Hidrobiología y Acuicultura de Três Marias, Minas Gerais, donde fueron reproducidas artificialmente. Inmediatamente después de la eclosión, aproximadamente 100 larvas de cada especie fueron acondicionadas en dos incubadoras de plástico. El comportamiento de las larvas fue registrado diariamente y fueron recolectadas 14 larvas de cada especie para análisis morfológico del cuerpo. En el primer día después de la eclosión las larvas de P. costatus y P. argenteus presentaban cuerpos alargados y transparentes. El saco vitelino se llenó de glóbulos de vitelo individualizados. En las dos especies, la aleta embrionaria circundaba la región caudal del cuerpo, la retina no presentaba pigmentos y el intestino estaba obliterado. En el segundo día, en las larvas de ambas especies habían surgido cromatóforos dendríticos, la boca estaba obliterada y fue registrada una aleta pectoral. Las larvas presentaban 38-43 miómeros en P. costatus y 42-43 en P. argenteus. En las dos ecpecies la vejiga de gas estaba inflada y el lumen del intestino ya estaba abierto. En el tercer día, la boca tanto del P. costatus como del P. argenteus ya estaba abierta en una posición subterminal. La retina estaba pigmentada, los arcos branquiales tenían protuberancias laminares y estaban parcialmente cubiertos por el opérculo. En el cuarto día, el patrón de pigmentación se presentó con mayor intensidad; la boca ocupó una posición terminal, el saco vitelino fue casi completamente reabsorbido y las aletas pectorales y caudales presentaban rayos mesenquimales en ambas especies. El intestino mostró un amplio lumen, con la mucosa plegada y el epitelio con borde estriado. Las larvas de ambas especies mostraron un comportamiento similar de natación durante el periodo de prueba. Nuestro estudio provee conocimiento sobre aspectos morfofisiológicos, identificación de especies, desarrollo y crecimiento larval y características ontogénicas de dos peces subtropicales de importancia para la pesca comercial y deportiva.

AbstractEarly development of fish larvae is a highly dynamic process and its study may provide important information about ontogenetic development, bioenergetic growth, behaviour, taxonomic characteristics for identification in natural environments, identification of spawning areas, and population monitoring. With the aim to provide knowledge about their growth and behaviour, to support larval rearing, and also taxonomic purposes, we studied the life history of the Prochilodus argenteus and P. costatus from hatching until the complete absorption of the yolk. Larvae were obtained through artificial reproduction at the Hydrobiology and Aquaculture Station of Três Marias, Minas Gerais, Brazil. Immediately after hatching, 100 larvae of each species were put in two plastic incubators for conditioning. On a daily basis, larvae behavior was recorded and 14 larvae of each species were collected to analyse body morphology. On the first day after hatching, larvae of P. costatus and P. argenteus showed an elongated and transparent body; the yolk sac was filled with individualized yolk globules. In both species, the embryonic fin rounded the caudal region of the body, the retina was non-pigmented and the gut was obliterated. At the second day post-hatching, larvae of both species dendritic chromatophores had emerged, the mouth was obliterated and the pectoral fin was observed. The larvae showed 38-43 myomeres in P. costatus and 42-43 in P. argenteus. For both species, the gas bladder was inflated and the lumen of the gut was already open. On the third day post-hatching, the mouth of P. costatus and P. argenteus was already open in a sub-terminal position; the retina was pigmented; the gill arches had lamellar protrusions and were partially covered by the operculum. On the fourth day post-hatching, the pigmentation pattern was maintained with greater intensity; the mouth occupied a terminal position, the yolk sac was almost completely reabsorbed, and the pectoral and caudal fins showed mesenchymal rays in both species. The gut showed a broad lumen with folded mucosa and epithelium with striated border. The larvae of both species showed similar swimming behaviour. Our study provided understanding about the morphophysiological aspects, species identification, larval development and growth, and the ontogenic characteristics of two Neotropical fishes with importance for commercial and sports fishing. Rev. Biol. Trop. 64 (2): 537-546. Epub 2016 June 01.

The large fruit-eating phyllostomid bat, Artibeus lituratus (Olfers, 1818), forearm 69-75 mm, body mass 66-82 g, has a diversified geographic distribution in the Neotropical region. Therefore it is subjected to different climatic conditions that affect its reproduction, leading to different reproductive strategies such as continuous reproduction, seasonal monoestry or seasonal bimodal polyestry. In this study we used morphometric and histological methods to analyze the annual reproductive activity of A. lituratus males in a population living in the Atlantic Forest, Southeastern Brazil. Testis mass, epididymis mass, gonadosomatic index, seminiferous tubule diameter, and Leydig cell nucleus diameter showed no significant differences (p > 0.05) in the two seasons (wet: October to March; dry: April to September). Additionally, the cauda epididymis was packed with sperm throughout the period of study. Our data indicate that in this population spermatogenic activity was continuous throughout the year. Slight variations in accumulated frequency of pre-meiotic, meiotic and post-meiotic stages of the seminiferous epithelium cycle were observed when compared to other bat species, probably due to species-specific characteristics.

Jaús Zungaro jahu (Ihering, 1898), mantidos em estação de piscicultura, foram induzidos à reprodução com extrato bruto de hipófise de carpa. Seus ovos são telolécitos, arredondados (1,6 ± 0,1 mm de diâmetro), demersais, livres e cobertos por uma capa gelatinosa com 0,4 mm de espessura. O índice gonadossomático (peso da ova : peso total do peixe) de 2,8 foi semelhante ao de outros Pimelodidae. O número de ovos x g de ova-1 foi 804 ± 144. A eclosão dos embriões ocorreu 14,5 h pós-fertilização à temperatura de 27,3 ± 0,4º C. Os embriões recém-eclodidos apresentaram 3,9-4,3 mm de comprimento total (CT). Dezoito horas pós-eclosão (HPE) e 5,3 ± 0,1 mm CT, a retina estava pigmentada, a boca aberta e a flexão da notocorda tinha se iniciado. Às 36 HPE (6,4 ± 0,2 mm CT), observaram-se cromatóforos fusiformes alinhados verticalmente na nadadeira primordial; a notocorda já se encontrava flexionada. O saco vitelínico encontrava-se quase que inteiramente absorvido às 48 HPE (7,3 ± 0,2 mm CT). Com 128 HPE (8,6 ± 0,6 mm TL), as nadadeiras peitoral, dorsal, adiposa, caudal, anal e pélvica estavam formadas e a nadadeira primordial já havia sido reabsorvida. Com 224 HPE (16,6 ± 2,5 mm CT), a metamorfose se completou e as larvas se transformaram em juvenis.

Hatchery-kept catfish jahus Zungaro jahu (Ihering, 1898) were induced to spawn with carp pituitary extract. The telolecithal eggs were round (1.6 ± 0.1 mm in diameter), demersal, free, and covered with a 0.4 mm-thick jelly coat. The gonadosomatic index of 2.8 was comparable to that of other Pimelodidae. The number of eggs x g of ova-1 was 804 ± 144. Hatching occurred 14.5 h after fertilization, at a temperature of 27.3 ± 0.4º C. The newly-hatched embryos measured 3.9-4.3 mm of total length (TL). At 18 h post-hatching (HPH; 5.3 ± 0.1 mm TL), the retina was pigmented, the mouth opened and dorsoflexion of the notochord had initiated. At 36 HPH (6.4 ± 0.2 mm TL), fusiform chromatophores were vertically arranged in the primordial fin fold and the notochord was dorsoflexed. The yolk sac was almost exhausted by 48 HPH (7.3 ± 0.2 mm TL). At 128 HPH (8.6 ± 0.6 mm TL) the pectoral, dorsal, adipose, caudal, anal, and pelvic fins were readily observable whereas the primordial fin fold was no longer visible. At 224 HPH (16.6 ± 2.5 mm TL), the metamorphosis was completed and the larvae had acquired the juvenile appearance.

In South America, one important symptom of the failure of fish passages to sustain fish migratory recruitment is the inability of eggs and larvae to reach the nurseries. This is especially so when the breeding areas are located upstream of a reservoir, and the floodplain is downstream of the dam. Therefore, the transport of fish larvae and eggs across reservoir barriers is a key factor in the development of effective conservation strategies. In this paper, we evaluate the potential for migratory fish larvae and egg transportation across a small size reservoir in eastern Brazil. We sampled fish daily between 15th October 2002 and 15th February 2003 (spawning period) in the Mucuri River, immediately upstream of the reservoir and downstream of the Santa Clara Power Plant dam. Our study was the first to indicate the possibility of successful larval passage through the reservoir of a hydroelectric reservoir and dam in South America, and showed that the passage of migratory fish larvae was associated significantly with residence time of water in the reservoir. The relatively short water residence time and elevated turbidity of the Santa Clara's reservoir waters during the rainy season certainly contributed to the successful passage, and can be considered as key factors for a priori evaluations of the feasibility of a downstream larval passage.

A traíra, Hoplias malabaricus (Bloch, 1794), da família Erythrinidae, encontra-se espalhada pelas bacias fluviais da América do Sul. Determinou-se a capacidade de suporte das células de Sertoli (espermatócitos primários: células de Sertoli e espermátides: células de Sertoli), índice meiótico (espermátides: espermatócitos primário) e o número de gerações mitóticas de espermatogônias desse peixe. Os indivíduos foram capturados no reservatório de Igarapava, rio Grande, bacia do Alto Paraná, Brasil. Fragmentos dos testículos de três traíras sexualmente maduras foram fixados em glutaraldeído a 5%, e incluídos em metacrilato. Cortes seriados de 2 e 3 µm de espessura foram corados em azul de toluidina a 5%. Contagens histológicas feitas em cistos de espermatócitos primários e espermátides revelaram, respectivamente, 326 ± 99 e 468 ± 73 núcleos destas células. A capacidade de suporte das células de Sertoli foi consideravelmente mais alta para espermátides (113,3 ± 16:1) do que para espermatócitos primários (71 ± 5:1). Ocorreram entre oito e dez gerações de espermatogonias antes de darem origem aos espermatócitos primários. Esses valores encontravam-se dentro da amplitude de gerações já registrada para teleósteos de água doce de fertilização externa. Correlações entre o número de células de Sertoli por cisto e de espermatócitos primários e entre células de Sertoli e espermátides por cisto foram estatísticamente signficativas (p < 0,05).

The Erythrinidae trahira, Hoplias malabaricus (Bloch, 1794), is widespread throughout South America river basins. We determined Sertoli cell supporting capacity (ratio of primary spermatocytes: Sertoli cells and spermatids: Sertoli cells), meiotic index (ratio of spermatids: primary spermatocytes) and the number of spermatogonial mitotic generations of this fish. The fish were captured in the Igarapava reservoir, Grande River, Alto Paraná River basin, Brazil. Testis fragments of three sexually mature trahiras were fixed in 5% buffered glutaraldehyde solution and embedded in glycol methacrylate. Serial sections of 2 and 3 µm in thickness were stained with 0.5% toluidine blue. Histological counts from cysts of primary spermatocytes and spermatids revealed, respectively, 326 ± 99 and 468 ± 73 nuclei of these cells. Sertoli cell supporting capacity was considerably higher for spermatids (113.3 ± 16:1) when compared to primary spermatocytes (71 ± 5:1). Between eight and ten spermatogonial generations were formed to give rise to primary spermatocytes. These values were within the generation range of those already found in freshwater teleosts of external fertilization. Correlation between the number of Sertoli cells and primary spermatocytes per cyst, and Sertoli cells and spermatids per cyst were statistically significant (p < 0.05).

Observações in loco e vídeo filmagens foram coletadas na janela da escada de peixes da UHE Igarapava (EPUG), rio Grande, sudeste do Brasil, entre 1º de março e 30 junho de 2004. Realizaram-se quatro experimentos com dois observadores humanos (Observador 1 e Observador 2) que observaram a passagem de peixes na janela da EPUG enquanto uma vídeo câmera Sony 3CCD (Observador 3) registrou simultaneamente a passagem de peixes. Os dois observadores humanos registraram in situ a passagem de peixes no visor da escada enquanto a câmera os filmava ao mesmo tempo. Os experimentos, cada um com uma hora de duração, foram realizados durante o ciclo diário, utilizando-se iluminação de espectro completo. Registraram-se as espécies, o número de indivíduos e o horário de passagem. Os registros de cada observador humano in situ foram comparados com os dos vídeos. Consideraram-se curimba (Prochilodus lineatus), mandi-amarelo (Pimelodus maculatus), piau-três-pintas (Leporinus friderici) e ferreirinha (Leporinus octofasciatus) como espécies alvo, tendo em vista sua alta freqüência de ocorrência na escada de peixes da UHE Igarapava. O número de espécies e o número de indivíduos não foram estatisticamente diferentes entre observadores. Por outro lado, o número de espécies e o número de indivíduos que passaram pelo visor foram estatisticamente diferentes entre experimentos. Assim, demonstrou-se que os três observadores registraram o mesmo número de espécies e contaram o mesmo número de indivíduos, mesmo quando as duas variáveis diferiram significativamente entre experimentos. Concluiu-se que o sistema de vídeo imagem constitui um método eficaz para avaliação da passagem de peixes na escada de peixes de Igarapava.

On site human observations and video images were collected and compared at the window of the Igarapava Dam fish ladder (IDFL), rio Grande , Southeastern Brazil, between March 1st and June 30th, 2004. We conducted four experiments with two humans (Observer 1 and Observer 2) observing fish passage in the IDFL window while a Sony 3CCD video camera (Observer 3) recorded fish passage at the same time. Experiments, each one hour in length, were distributed throughout the diel cycle using full spectrum lights. We identified fish species, the number of individuals for each species, and the real time that they passed. Counts from each human observer were compared to the video counts. The fish species most commonly observed in the window were - curimba (Prochilodus lineatus), mandi-amarelo (Pimelodus maculatus), piau-três-pintas (Leporinus friderici) and ferreirinha (Leporinus octofasciatus). The number of species and individuals were indistinguishable for the three observers. But, the number of species and individuals were significantly different among experiments. Thus, the three observers register the same number of species and count the same number of individuals even when these two response variables differ significantly among experiments. Based on these results, we concluded that the video count was an accurate method to assess fish passage at the IDFL.

O sêmen das seguintes espécies de Characiformes neotropicais foi testado para armazenamento em ambiente resfriado: Brycon lundii, Piaractus mesopotamicus, Leporinus elongatus, Leporinus friderici, Prochilodus lineatus e Prochilodus marggravii. Amostras de sêmen, obtidas por massagem da parede celômica, foram armazenadas em saco plástico com ar ou oxigênio ou em tubo plástico com ar, e mantidas resfriadas entre 1,7-4,9º C. A taxa de motilidade espermática foi estimada usando-se NaCl 50 mM como solução ativadora. O sêmen com menor duração de viabilidade (7 h) foi o de L. friderici, quando a taxa de motilidade espermática alcançou ~30%, enquanto que o de maior duração (20 h) foi o de P. lineatus. A fertilização de ovócitos utilizando sêmen refrigerado por 8 h de Prochilodus marggravii produziu 88-90% de embriões viáveis. O método de armazenamento desenvolvido neste trabalho tem aplicações práticas, especialmente no manejo reprodutivo de peixes em estações de piscicultura.

Sperm of the following Neotropical Characiformes fish species were tested for cold storage: Brycon lundii, Piaractus mesopotamicus, Leporinus elongatus, Leporinus friderici, Prochilodus lineatus and Prochilodus marggravii. Each sperm sample was split into two aliquots. The first was placed into a plastic bag with air or oxygen and the second, in a plastic tube with air. The samples were maintained at temperatures between 1.7-4.9 ºC. The rate of sperm motility was estimated using a 50 mM NaCl solution as the activating solution. The shortest sperm storage duration (7 h) was recorded for L. friderici, when the sperm motility rate reached ~ 30%, whereas the longest duration (20 h) was obtained with the sperm of P. lineatus. A fertilisation test using Prochilodus marggravii sperm refrigerated for 8 h yielded 88-90% of viable embryos. The refrigerated storage method could be of practical applications, especially in fish reproductive management at hatchery stations.

The reproductive activity parameters of the teleosts Pimelodus maculatus Lacépède, 1803, Leporinus amblyrhynchus Garavello & Britski, 1987 and Schizodon nasutus Kner, 1859 was evaluated at a newly formed reservoir in the Araguari River, Paraná River basin, Southeast Brazil. The fishes were captured by gill nets bimonthly from November 1997 to November 1998 at three sampling stations. The stages of gonad development were identified macroscopically in the field and then confirmed by histological analysis in the laboratory. The females of all species reached larger standard length than the males. Pimelodus maculatus in reproductive activity were captured only in November, 1997 and January, 1998 whereas L. amblyrhynchus and S. nasutus were in activity throughout the year. The gonadosomatic index reached the peak during the advanced maturation stage in all species, but the hepatosomatic index and coelomic fat index exhibited distinct tendencies. Length at first maturity was 9.5 cm SL for amblyrhynchus females and 17.1 and 13.0 cm SL, respectively, for S. nasutus females and males. L. amblyrhynchus and S. nasutus are partial spawners. The size at first maturity and type of spawning of P. maculatus were not possible to determine in this work.