Protection of spawning habitat for potamodromous fish, an urgent need for the hydropower planning in the Andes

Because dams block migratory routes of potamodromous fish to their spawning areas, and energy generation changes natural flow seasonality, it is necessary to identify spawning areas and their conditions. This information will help in management decisions in the Magdalena River basin regarding the future hydropower development. We identified which characteristics of the tributaries to the Magdalena River are important for determining potamodromous fish spawning grounds, and we estimated the percentage of future loss of spawning areas because of dam development. Ichthyoplankton density is directly related to the floodplain area, and inversely related with channel slope. Low channel slopes offer adult fish a longer distance for their upstream migration and a longer time for embryo development during their drift downstream from the spawning areas to nursery habitats (floodplain lakes). These features could increase the migration distance of the adults, the time for initial embryo development, and, because of its relationship with nursery habitats access, the offspring survival. The potential loss of the actual spawning grounds in the river network was estimated to be nearly 70% because of new dams. Our findings will help to reduce conflicts between hydropower and ecological interests.(AU)

La construcción de hidroeléctricas puede afectar la reproducción de los peces migratorios potamódromos, ya sea porque las represas bloquean las rutas migratorias a sus áreas de desove, o porque la generación de energía cambia la estacionalidad del flujo natural. Esto hace necesario generar información sobre las áreas de desove y sus características, que permitan tomar decisiones de manejo, teniendo en cuenta el desarrollo hidroeléctrico propuesto a futuro en la cuenca del río Magdalena. Identificamos qué características de algunos afluentes del río Magdalena son importantes para los desoves y estimamos el porcentaje de pérdida futura de áreas de desoves debido al desarrollo hidroeléctrico. La densidad del ictioplancton se relacionó directamente con el área de la llanura aluvial e inversamente con la pendiente del canal. Estas características aumentan la distancia de migración de los adultos maduros, el tiempo para el desarrollo inicial del embrión y la supervivencia de la descendencia debido a la proximidad y/o conectividad con los hábitats de cría. La pérdida potencial de las zonas de desove en la red fluvial se estimó en casi el 70% debido a las nuevas presas. Nuestros hallazgos ayudarán a tomar decisiones sostenibles para reducir los conflictos entre intereses de desarrollo hidroeléctrico y ecológicos.(AU)

Cambios morfológicos en la ontogenia temprana de Chirostoma riojai / Morphological changes in the early ontogeny of Chirostoma riojai

El charal de Toluca Chirostoma riojai es un pez de alto valor cultural e ictiológico. Los trabajos sobre esta especie se enfocan en el tipo de alimentación o forman parte de revisiones taxonómicas y son pocos los estudios sobre los cambios morfológicos durante su ontogenia. Se evaluó la figura de C. riojai mediante morfometría geométrica desde su eclosión hasta los 90 días de vida. Los ejemplares se cultivaron en condiciones controladas y fueron fijados 171 organismos pertenecientes a 11 intervalos de edad incluidos en cinco fases: embrión libre, apterolarva, pterolarva, juvenil y adulto. Se usaron seis puntos anatómicamente homólogos en una primera configuración de marcas y en una segunda se delinearon dos contornos (dorsal y ventralmente) de la región anterior. Un análisis de componentes principales mostró una fuerte diferenciación en su figura durante la transición larva-juvenil, en tanto un análisis de variables canónicas señaló diferencias significativas (ps<0.001) entre los 11 grupos de edad. La regresión lineal entre el logaritmo del tamaño centroide y las distancias procustes muestran que los organismos mantienen un cambio de figura constante hasta el término del periodo larvario, punto en el que el periodo juvenil comienza y las modificaciones en su figura disminuyen. La descripción del desarrollo temprano de C. riojai sin considerar el desarrollo de las aletas, muestra que la característica con el mayor cambio es el desplazamiento del poro anal, seguido por el alargamiento de la región cefálica. El tamaño y la figura de C. riojai durante su vida temprana pueden servir para diferenciar faces de desarrollo y ser utilizada en otras especies hermanas para evaluar si su figura es específica en cada fase. Los cambios morfológicos de C. riojai durante su vida temprana se pueden describir de forma gradual hasta el periodo larval y saltatoria en el cambio a juvenil.

Toluca silverside Chirostoma riojai is a fish with high cultural and ictiological values. Studies on this species have focused on the type of diet or as part of taxonomic reviews, while few reports are known on the morphological changes during its ontogeny. In this study the shape of C. riojai was evaluated by means of geometric morphometrics from hatchings up to 90 days-old individuals. Specimens of C. riojai were cultivated in controlled conditions, and 171 organisms there fixed, belonging to 11 age intervals included within five phases: free embryo, apterolarva, pterolarva, juvenile, and adult. There were used six landmarks in an initial configuration, and in a second configuration there were outlined two contours (dorsal and ventral) on the anterior region. A principal component analysis showed a strong differentiation in the shape during the transition larva-juvenile, for both an analysis of canonical variables found significant differences (ps<0.001) between the 11 age groups. The linear regression between the logarithm of the size centroid and procustes distances, showed that the individuals maintain a constant change in shape up to the end of the larval phase, at which time the youth stage begins and the changes in its shape decreases. The description of the early development of C. riojai without considering the development of the fins, shows that feature with greatest change is the movement of the anal pore, followed by the lengthening of the cephalic region. The size and shape of C. riojai during its early life could serve to differentiate developmental phases and could be used with other sister species to assess whether their shape is specific in each phase. The morphological changes of C. riojai during his early life could be described in a gradual form up to the the larval period, while saltatory in the change to juvenile.

Functional integrity of Colossoma macropomum (Cuvier, 1816) sperm cryopreserved with enriched extender solutions

Cryoprotectant solutions are used to protect the sperm from alterations caused by the low temperature in the cryopreservation process. We evaluated the quality of Colossoma macropomum semen after freezing, using dimethyl sulfoxide (DMSO) as a cryoprotectant, combined with two extender solutions (T1 - Solution 1: Glucose 90.0 g/L, Sodium Citrate 6.0 g/L, EDTA 1.5 g/L, Sodium Bicarbonate 1.5 g/L, Potassium Chloride 0.8 g/L, Gentamycin Sulphate 0.2 g/L, and T2 - Solution 2: Glucose 90.0 g/L, ACP(r)-104 10.0 g/L). Motility rate and motility time did not differ between T1 and T2 and were lower than fresh semen. The number of normal sperm was significantly different in treatments T1 (15.1%) and T2 (21.9%), and both showed a reduction in the percentage of normal sperm compared to fresh semen (57.4%). The values found for the rates of fertilization and hatching, mitochondrial functionality and sperm DNA, did not differ between the treatments (T1 and T2). Regarding membrane integrity, there was a higher percentage of spermatozoa with intact membranes in T1 (53.4%) than T2 (43.7%). The extender solutions, combined with 10% DMSO, maintained the sperm DNA intact in almost all the C. macropomumsperm cells, however there was a loss in their functionality.

As soluções crioprotetoras são utilizadas para proteger os espermatozoides das alterações causadas por baixas temperaturas durante o processo de criopreservação. Avaliamos a qualidade do sêmen de Colossoma macropomumapós o congelamento, utilizando dimetilsulfóxido (DMSO) como crioprotetor, combinado com duas soluções diluidoras (T1 - Solução 1: Glicose 90,0 g/L, Citrato de Sódio 6,0 g/L, EDTA 1,5 g/L, Bicarbonato de Sódio 1,5 g/L, Cloreto de Potássio 0,8 g/L, Sulfato de Gentamicina 0,2 g/L, e T2 - Solução 2: Glicose 90,0 g/L, ACP(r)-104 10,0 g/L). A taxa de motilidade (%) e o tempo de motilidade (s) não diferiram entre T1 e T2, porém foram mais baixos do que no sêmen fresco. O número de espermatozoides normais foi significativamente diferente nos tratamentos T1 (15,1%) e T2 (21,9%), e ambos mostraram uma redução na porcentagem de espermatozoides normais, comparado ao sêmen fresco (57,4%). Os valores encontrados para as taxas de fertilização e eclosão, funcionalidade mitocondrial e DNA do esperma, não diferiram entre os tratamentos (T1 e T2). Para a integridade da membrana, houve uma porcentagem mais elevada de espermatozóides com a membrana intacta em T1 (53,4%) do que T2 (43,7%). As soluções diluentes combinadas com DMSO a 10% preservaram o DNA espermático intacto em quase todas as células do sêmen de C. macropomum, mas houve perda na funcionalidade dos mesmos.

Aloe vera na criopreservação do sêmen de tambaqui (Colossoma macropomum) / Aloe vera in the cryopreservation of tambaqui (Colossoma macropomum) sperm

This study aimed to evaluate the extract of Aloe vera (AV) associated or not with 10% Dimethylsulfoxide (DMSO) in cryopreservation of tambaqui semen. For the formation of the pools (n= 14), 30 males were hormonally induced twice. Each pool had the objective motility, curvilinear velocity, straight-line velocity, average path velocity and morphology analyzed before and after cryopreservation of semen. The means for cryopreservation were constituted of Powder Coconut Water-104 diluent added DMSO and/or AV (5 or 10%). After cryopreservation, motility, velocities and morphology were reduced significantly when compared to fresh semen. For sperm motility the best treatment was that using only DMSO (20,86±8,31) and DMSO + 5% AV (15.71±9.77). For the velocities, the worse treatment was DMSO+10% AV. Treatment with only the addition of DMSO had a significantly higher effect than others on percentage of morphologically normal sperm. The mean correlation found was between motilityand the rate of morphologically normal sperm (r = 0.687). In conclusion, the addition of AV does not provide greater protection for spermatozoa during cryopreservation.

Growth differentiation factor 9 and bone morphogenetic protein 15 expression in previtellogenic oocytes and during early embryonic development of Yellow-tail Kingfish Seriola lalandi

BACKGROUND: During fish oocyte maturation, specific molecules are expressed and accumulated within oocyte until fertilization and embryo development. Special attention have been paid in members of the transforming growth factor (TGF-ß) superfamily; growth differentiation factor 9 (GDF9/gdf9) and bone morphogenetic protein 15 (BMP15/bmp15), which exert regulatory functions during oocyte maturation and follicle development. However, little attention has been paid to the involvement of these molecules during embryogenesis considering its importance for the formation of a good quality egg and subsequent embryo survival. The purpose of this study was to analyze the expression of gdf9 andbmp15 in previtellogenic oocytes and during early embryonic development in Seriola lalandi, a pelagic fish with increasing prospect for its aquaculture development, which however, show high mortality at embryo and larval stages. RESULTS: Through RT-qPCR it was found that gdf9 expression was higher in previtellogenic oocytes decreasing after ovulation. This expression profile agrees with its participation in early stages of the follicular development. The transcripts for bmp15 also showed the highest levels in previtellogenic oocytes, however this expression was lower than obtained with gdf9. Conversely, in recently spawned oocytes mRNA bmp15 levels were highest than observed to gdf9. This, is consequent with the main role proposed for this growth factor at the final fish oocyte maturation: avoid the ovulation of an immature oocyte. During embryo development, low levels of mRNA were detected to gdf9, with an increase in 48 H post-fertilization embryos. The bmp15 expression did not change throughout development and was higher than gdf9 at 16 cells, blastula and appearance embryos stages. CONCLUSIONS: Both (gdf9 and bmp15) expression profiles in previtellogenic oocytes and newly spawned eggs are consistent with the described functions for these growth factors in vertebrate ovarian physiology in early and late stages of the follicular development. So, these genes could be considered as quality biomarkers at these stages. However, further studies of these proteins throughout folliculogenesis, are necessaries to fully understand their functions during the oocyte formation. In addition, the persistent expression of these growth factors during development, allows us to speculate possible roles in embryonic processes, which must also be addressed.

Desarrollo embrionario del capaz pimelodus grosskopfii (Steindachner, 1879) / Embryonic development of capaz pimelodus grosskopfii (Steindachner, 1879)

El conocimiento del desarrollo embrionario en los peces es especialmente importante en especies nativas con potencial para la piscicultura, en virtud que permite identificar eventos morfológicos y cronológicos, necesarios para establecer prácticas de manejo durante las fases de incubación y larvicultura. El capaz (Pimelodus grosskopfii) es una especie con potencial para cultivo comercial, por sus hábitos alimenticios omnívoros y aceptación de su carne en el mercado. Para estudiar el desarrollo embrionario de la especie, ejemplares adultos sexualmente maduros fueron inducidos a la reproducción con extracto de hipófisis de carpa (5,75 y 4,0 mg Kg-1, hembras y machos, respectivamente). Los óvulos seminados fueron incubados en un sistema de flujo ascendente de 30 L a 27 +/- 1 °C. Las muestras (n=30) fueron colectadas al momento de la extrusión, durante la fertilización y cada 15 minutos a partir de las 0 horas postfertilización (HPF) hasta las 2 horas y cada 30 minutos desde las 2 HPF hasta 5 HPF; finalmente, entre las 5 HPF y la eclosión, cada 60 minutos. Los óvulos fertilizados presentaron forma esférica, sin adherencias y con amplio espacio perivitelino. El desarrollo embrionario finalizó a las 12 HPF. La diferenciación del polo animal y vegetal ocurrió a las 0,2 HPF, el primer clivaje a las 0,3 HPF, el blastodisco alto y estratificado a las 1,8 HPF, el blastodisco achatado a las 3,3 HPF, la epibolia < a 50 por ciento se observó a las 4 HPF, el cierre del blastoporo a las 5,7 HPF, la diferenciación cráneo caudal e inicio de la neurolación a las 7 HPF, la diferenciación de las vesículas ópticas, óticas y vesícula de Kupffer a las 8,5 HPF, la liberación de la cola del vitelo a las 10 HPF, los primeros movimientos se observaron a las 10,5 HPF y finalmente la eclosión ocurrió a las 12 HPF. Las larvas al eclosionar presentaron una longitud total de 2987+/-67 um, sin pigmentación, tracto digestivo rudimentario, sin abertura bucal ni anal y presencia de cromatóforos...

The knowledge of embryonic development in fish is important in native species with potential for fish farming, by virtue of which it makes possible to identify morphological and chronological events to establish management practices during incubation periods and larviculture. The capaz (Pimelodus grosskopfii) is a species with potential for commercial crop, due to their omnivorous eating habits and acceptance of its meat in the market. To study the embryonic development of the species, sexually mature adult specimens were induced to reproduce with carp pituitary extract (5.75 and 4.0 mgKg-1, females and males, respectively). The inseminated oocytes were incubated in an upward flow system 30 a 27 +/- 1 ° C. The samples (n = 30) were collected at the same time of the extrusion, during fertilization, and every 15 minutes starting from 0 to 2 hours post fertilization (HPF) and every 30 minutes from 0 to 2 HPF, and every 30 minutes from 2 to 5 HPF; finally, between 5 HPF and hatching every 60 minutes. The fertilized oocytes had a spherical shape without adhesions and large perivitelline space. Embryonic development took 12 HPF. The differentiation in animal and vegetal pole occurred at 0.2 HPF, the first cleavage at 0.3 HPF, stratified and high blastodisc at 1.8 HPF, flattened blastodisc at 3.3 HPF, the epiboly <50 percent was observed at 4 HPF, the closure of the blastopore at 5.7 HPF, cranial-caudal differentiation and starting the neurolation at 7 HPF, the differentiation of the optic vesicles, otic and Kupffer's vesicle at 8.5 HPF, tail of the vitelum was released at 10 HPF, first movements were observed at 10.5 and finally hatching occurred at 12 HPF. When the larvae hatched, they showed a total length of 2987+/-67 µm, without depigmentation, rudimentary digestive system without oral and anal opening and the presence of chromatophores on the yolk sac.

Estudio histológico del tracto digestivo del neón cardenal paracheirodon axelrodi (Characidae) / Histological study of digestive tract of the neón cardenal paracheirodon axelrodi (Characidae)

Paracheirodon axelrodi es el pez ornamental que más se exporta en Colombia. Sin embargo, se desconocen varios aspectos de su biología básica. Se estudió la histología del tracto digestivo. Se sacrificaron 15 ejemplares (MS 222, 0,5 g/L), fijados en formaldehído al 4 por ciento y decalcificados con ácido nítrico 7 por ciento. Se siguió el procedimiento para H&E. El tracto digestivo de P. axelrodi presentó cuatro capas constitutivas: mucosa, submucosa, muscular y serosa. La mucosa de la boca presentó un epitelio escamoso estratificado no queratinizado con células caliciformes y sin botones gustativos, una submucosa de tejido conectivo laxo y una capa de músculo estriado esquelético. Los dientes son cónicos y abundantes. La capa serosa a lo largo del tracto digestivo es delgada compuesta de tejido conectivo laxo. La capa mucosa, submucosa y muscular del esófago posee la misma conformación tisular de la boca, sin embargo, la capa muscular presenta dos orientaciones. La mucosa del estómago está compuesta por epitelio cilíndrico simple con glándulas gástricas, submucosa de tejido conectivo laxo y una capa de músculo liso en dos orientaciones. Las capas del intestino exhi-bieron una composición tisular similar a la del estómago, sin glándulas gástricas. La mucosa presentó células caliciformes especialmente hacia la región posterior y un aumento en la longitud de los pliegues intestinales. La conformación tisular y morfológica del tracto digestivo de P. axelrodi lo ubica como un pez de hábitos alimenticios carnívoros pero de pequeñas presas.

Cardinal neon, Paracheirodon axelrodi is the most exported ornamental fish in Colombia. However, many aspects of its biology are unknown. A histological study of the digestive tract was carried out and 15 specimens were sacrificed with MS 222, 0.5 g/L, fixed in 4 percent formaldehyde and decalcified with 7 percent nitric acid. H&E technique was followed. P. axelrodi digestive tract showed four constitutive layers: mucosae, submucosae, muscular, and serosa. Mouth mucosae presents a stratified nonkeratinized squamous epithelium with many goblet cells, and no taste buds, submucosae with areolar connective tissue, and skeletal muscular layer. Teeth were conical and abundant. Along the whole intestinal tract the serous was a very thin connective tissue layer. Esophagus mucosae, submucosae, and muscular layer were similar to those of the mouth. However, muscular layer presented two layers in different orientations. Stomach mucosae were made of simple cylindrical epithelium with gastric glands. Submucosa did present areolar connective tissue, and muscular layer exhibited smooth muscle in two different orientations. The intestinal layers were similar to those of the stomach, but without gastric glands. Mucosae presented goblet cells especially at the posterior region. Intestinal folds were also observed. Tisular and morphological structure of P. axelrodi digestive tract suggests a small prey carnivorous fish.

Structural analysis of the Pimelodus maculatus (Lacépède, 1803) embryogenesis (Siluriformes: Pimelodidae)

The fish embryonic development comprises the events between the egg fertilization up to larvae hatching, being useful for the identification of viable eggs in productivity and survival studies as well as in raising experiments of several species. The goal of the present study was to characterize the embryonic development of Pimelodus maculatus (Siluriformes; Pimelodidae). The embryogenesis was typical of teleosteans, but with differences in relation to other species such as duration of development, type of blastocoel, moment of somite segmentation among others. Six stages of embryonic development were defined: zygote, cleavage, blastula, gastrula, organogenesis (divided in phases: early segmentation and late segmentation) and hatching with a period of incubation equal to 13 hours at 29 ºC and 17 hours at 25 ºC. The extruded oocytes presented a mean diameter of 812 µm before and 1066 µm after hydration. When fertilized, they presented a yellowish coloration and a gelatinous layer surrounding the chorion. The cleavage pattern is described as: 2; 4; 8 (4x2); 16 (4x4); 32 (4x8) and 64 (2x4x8) blastomeres up to morula phase (+64 cells). It was also possible to observe at this phase, the beginning of the formation of the yolk syncyctial layer (YSL). Afterwards, the blastula and gastrula stages followed. The end of gastrula was characterized by the formation of the yolk plug. Subsequently, the differentiation between cephalic and caudal regions began, along with the embryo elongation, structuring of optic, Kupffer's and otic vesicles besides a previously unidentified structure in the yolk syncyctial layer. The end of this stage is typified by the tail detachment. The late segmentation phase was distinguished by a free tail, presence of more than 30 somites, optic and otic vesicles, development of posterior intestine, pigmentation of cephalic and caudal regions of yolk sac and embryo growth. The recently-hatched larvae presented a primordial digestive tract, quite evident and pigmented eyes, closed mouth, encephalic vesicles and a mean length of 3410 µm.

O desenvolvimento embrionário de peixes compreende eventos que ocorrem desde o ovo fertilizado à eclosão das larvas, podendo auxiliar na identificação dos ovos viáveis em estudos de produtividade e sobrevivência, como também nas pesquisas de cultivo desses animais. O objetivo do presente estudo foi caracterizar o desenvolvimento embrionário do Pimelodus maculatus (Siluriformes; Pimelodidae). A embriogênese foi característica de teleósteos, apresentando variações que difere de outras espécies como, tempo de desenvolvimento, tipo da blastocele, momento de segmentação dos somitos, entre outros. Seis estágios de desenvolvimento embrionário foram definidos: zigoto, clivagem, blástula, gástrula, organogênese (dividido em fases: segmentação inicial e segmentação final) e eclosão com período de incubação de 13 horas à 29ºC e de 17 horas à 25ºC. Os ovócitos extrusados apresentaram diâmetro médio de 812 µm antes da hidratação e após 1066 µm. Após a fertilização, apresentaram coloração amarelada e uma camada gelatinosa envolvendo o córion. O padrão de clivagens foi descrito como segue: 2; 4; 8 (4x2); 16 (4x4); 32 (4x8) e 64 (2x4x8) blastômeros até a fase de mórula (+64 células). Também foi possível observar nesta fase, o início da formação da camada sincicial do vitelo (CSV). Em seguida foram observados os estágios de blástula e gástrula. O final da gástrula caracterizou-se pela formação do tampão vitelino. A seguir, iniciou-se a diferenciação das regiões cefálica e caudal, o alongamento do embrião, estruturação das vesículas ópticas, de Kufper, óticas e de uma estrutura não identificada na literatura localizada na camada sincicial do vitelo. O final deste estágio é demarcado pelo desprendimento da cauda. A fase de segmentação final caracterizou-se pela cauda livre, presença de mais de 30 somitos, vesícula óptica e ótica, desenvolvimento do intestino posterior, pigmentação nas regiões cefálica e caudal do saco vitelino e crescimento do embrião. As larvas recém-eclodidas apresentaram esboço do trato digestório, olhos bem evidentes e pigmentados, boca fechada, presença das vesículas encefálicas e com comprimento médio de 3410 µm.

Comparación del desarrollo embrionario de piaractus brachypomus (Serrasalmidae) y pseudoplatystoma sp. (Pimelodidae) / Comparison of the embryonic development of piaractus brachypomus (Serrasalmidae) and pseudoplatystoma sp. (Pimelodidae)

Pseudoplatystoma sp y Piaractus brachypomus son dos especies de peces dulceacuícolas endémicas de América del Sur de alto interés comercial como peces de cultivo. El objetivo de este trabajo fue comparar el desarrollo embrionario hasta la eclosión en estas dos especies. Para observar el desarrollo embrionario se incubaron oocitos fertilizados, obtenidos por inducción hormonal, en incubadoras de flujo ascendente tipo Woynarovich bajo condiciones controladas de calidad de agua. Los clivajes, la fase de blástula, gástrula hasta el cierre del blastoporo y eclosión en Pseudoplatystoma sp se observaron entre las 0:30 - 18:00 HPF, mientras que en P. brachypomus fue más rápida, observándose desde las 0:30 hasta las 14:00 HPF, siendo más homogénea que en Pseudoplatystoma sp.

Pseudoplatystoma sp. and Piaractus brachypomus are two species of freshwater fishes endemic to South America as a high commercial crop species. The aim of this study was to compare the embryonic development of these two species until they hatch. To observe embryonic development fertilized oocytes were incubated obtained by hormonal induction in upwelling incubators Woynarovich type under controlled conditions of water quality. The cleavages were observed for Pseudoplatystoma sp. from 0:30 hours post fertilization (HPF) until 2:00 pm (HPF), whereas in P. brachypomus these occurred between 0:30 - 1:30 HPF. The stage of blastula, gastrula until the closure of blastopore Pseudoplatystoma sp. was observed in sp between 2:00 to 12:00 P. HPF while in P. brachypomus between 2:00 to 8:00. The hatching in Pseudoplatystoma sp was observed between 14:00 to 18:00 HPF, whereas P. brachypomus was faster, was observed from 12:00 until 14:00 HPF HPF, and was more homogeneous than Pseudoplatystoma sp.

Embryonic development of Bryconamericus caucanus (Characidae: Tetragonpterinae) under laboratory conditions / Desarrollo embrionario de Bryconamericus caucanus (Characidae: Tetragonpterinae) en condiciones de laboratorio

In this study we describe the early stages of development of Bryconamericus caucanus under laboratory conditions. Mature females (mean weight 8.12 g) received two intraperitoneal doses of Carp Pituitary Extract (1st dose of 0.5 mg / kg at time 0 and 2nd dose of 5 mg / kg 12 h later), and mature males received a single dose of 0.5 mg / kg at the time of the 2nd dose to the females. Extrusion of eggs was performed at 152.25 Accumulated Thermal Units. Eggs of B. caucanus were yellow, round shaped, non-adhesive, and the perivitelline space after hydratation was moderate. Hatching occurred 28 h 20 min after fertilization (21C, 594.3 Accumulated Thermal Units). The morphological features of the egg and early embryo of B. caucanus were similar to previous reports in other members of the Tetragonopterinae, but the embryonic development was particularly long in this species.

Se estudian, bajo condiciones de laboratorio, los estadios tempranos de desarrollo en Bryconamericus caucanus. Hembras maduras (peso promedio de 8,12g) recibieron dos dosis intraperitoneales de extracto de hipófisis de carpa (1a dosis de 0,5 mg/Kg en la hora cero y 2 dosis de 5 mg/Kg en la hora 12). Así mismo, los machos maduros recibieron una única dosis de 0.5 mg / kg en la 2 dosis de las hembras. Se llevó a cabo desove en seco a 152,25 grados-hora luego de la aplicación de la 2 dosis hormonal. Los huevos de B. caucanus eran amarillos, redondeados, no adhesivos y el espacio perivitelino luego de la hidratación fue moderado. La eclosión se registró 28 h 20 min después de la fertilización (594,3 grado-horas a 21C). La respuesta positiva a la hipofización y las características morfológicas del huevo y del embrión de B. caucanus fueron similares a los reportes previos en otros miembros de la subfamilia Tetragonopterinae, siendo el desarrollo embrionario de B. caucanus particularmente prolongado.

Estimating size at first maturity (L50) from Gonadossomatic Index (GSI) data

Correct estimates of size at first maturity (L50) are useful for fish stock management and different methods have been proposed. In this study we propose the use of a modified logistic to estimate L50, including a variable asymptote (A). We also test the use of the Gonadossomatic Index (GSI) as a flag to establish the reproductive status of each female fish. The method is demonstrated using GSI data for four Neotropical fish species: Characiformes: Astyanax fasciatus (n = 473) and Oligosarcus robustus (n = 297); Siluriformes: Loricariichthys anus (n = 427) and Trachelyopterus lucenai (n = 195). The results were stable enough to propose this method be used for other fish species with different life histories and with a relatively unconstrained sampling programs. Nevertheless, a wide scale test program is desirable to identify any possible bias in this approach.

Estimativas precisas do tamanho de primeira maturação (L50) são úteis para a gestão de estoques naturais, existindo diversos métodos disponíveis na literatura. No presente estudo é proposto um método alternativo através de uma equação logística modificada, incluindo-se uma assíntota variável (A). Testou-se igualmente o uso do Índice Gonadossomático (GSI) como indicativo do status reprodutivo para fêmeas de peixes. O método é demonstrado com dados de quatro espécies de peixes Neotropicais: Characiformes: Astyanax fasciatus (n = 473) e Oligosarcus robustus (n = 297); Siluriformes: Loricariichthys anus (n = 427) e Trachelyopterus lucenai (n = 195). Os resultados obtidos foram suficientemente estáveis para propor-se o emprego do método para outras espécies de peixes com diferentes histórias de vida, mesmo que em programas de amostragem limitados. Sugere-se, entretanto, avaliação da metodologia em larga escala como forma de identificar-se possíveis desvios da abordagem proposta.

Origin, evolution and homologies of the Weberian apparatus: a new insight / Origen, evolución y homologías del aparato weberiano: un nuevo acercamiento

The Weberian apparatus is essentially a mechanical device improving audition, consisting of a double chain of ossicles joining the air bladder to the inner ear. Despite being one of the most notable complex systems of teleost fishes and the subject of several comparative, developmental and functional studies, there is still much controversy concerning the origin, evolution and homologies of the structures forming this apparatus. In this paper I provide a new insight on these topics, which takes into account the results of recent works on comparative anatomy, paleontology, and ontogeny as well as of a recent extensive phylogenetic analysis including not only numerous otophysan and non-otophysan extant otocephalans but also ostariophysan fossils such as Chanoides macropoma, Clupavus maroccanus, Santanichthys diasii, Lusitanichthys characiformis, Sorbininardus apuliensis and Tischlingerichthys viohli. According to the evidence now available, the Weberian apparatus of otophysans seems to be the outcome of a functional integration of features acquired in basal otocephalans and in basal ostariophysans, which were very likely not directly related with the functioning of this apparatus, and of features acquired in the nodes leading to the Otophysi and to the clade including the four extant otophysan orders, which could well have been the result of a selection directly related to the functioning of the apparatus.

El aparato weberiano es esencialmente un dispositivo mecánico que mejora la audición, consiste en una doble cadena de osículos que unen la cámara de aire al oído interno. A pesar de ser uno de los sistemas complejos más notables de peces teleósteos y objeto de varios estudios comparativos, de desarrollo y funcionales, todavía hay mucha controversia sobre el origen, evolución y homologías de las estructuras que forman este aparato. En este trabajo se proporciona una nueva visión sobre estos temas, que tiene en cuenta los resultados de los últimos trabajos sobre la anatomía comparada, paleontología y la ontogenia, así como de un reciente análisis filogenético amplio que incluyen no sólo numerosos otocéfalos Otofisios y no Otofisios existentes, sino también fósiles Ostariofisios como Chanoides macropoma, Clupavus maroccanus, Santanichthys diasii, Lusitanichthys characiformis, Sorbininardus apuliensis y Tischlingerichthys viohli. Según las pruebas disponibles, el aparato weberiano de Otofisios parece ser el resultado de una integración funcional de las características adquiridas en otocéfalos basales y en ostariofisios basales, los cuales muy probablemente no estén directamente relacionados en el funcionamiento de este aparato, y las características adquiridas en los nodos que condujeron a los Otofisios y al clade incluyendo las cuatro órdenes existentes otofisios, que bien podrían haber sido el resultado de una selección directamente relacionada con el funcionamiento del aparato.

Caracterización genética de lotes de brycon orbignyanus utilizados en programas de repoblamiento / Genetic characterization of brycon orbignyanus stocks used in restocking programs

Objetivo. Caracterizar genéticamente dos lotes y una progenie de Brycon orbignyanusdestinados para programas de repoblamiento, utilizando la técnica molecular de RAPD (Random amplified polymorphic DNA). Materiales y métodos. Se analizaron 58 reproductores originarios de dos piscícolas ubicadas en las ciudades de Castillo (A:30 individuos) y Porto Ferreira (C:28 individuos), mantenidos en cautiverio hace seis años en la estación de acuicultura e hidrología de la Duke Energy Internacional (Geração Paranapanema) (São Paulo-Brasil). Treinta larvas de la progenie del lote A (B) también se analizaron. Resultados. Los 14 primers usados produjeron 87 fragmentos de los cuales 70.11% fueron polimórficos. Fueron observadas diferencias (p≤0.05) en la frecuencia de 31 fragmentos, con tres exclusivos para el lote A. Los valores de divergencia, distancia e identidad genética mostraron que la diversidad genética del lote A fue mantenida en la progenie y que existe una baja diferenciación entre los lotes de reproductores. El análisis de variancia molecular mostró que la mayor parte de la variación está dentro de cada lote (87.45%) y no entre ellos (12.55%). Este resultado se corroboró con los valores de FST (0.125) y con el dendrograma, que indicaron una moderada diferenciación genética, sin la formación de agrupamientos. Conclusiones. La diversidad genética fue preservada en la progenie debido al manejo eficiente de la reproducción. No hubo una diferenciación genética entre los lotes de reproductores, debido posiblemente a que el origen natural de ambos fue el río Paraná.

Efeito da vitamina C sobre o hematócrito e glicemia de alevinos de tilápia-do-nilo (Oreochromis niloticus) em transporte simulado / Effect of vitamin C over the haematocrit and glycemia of nile tilapia (Oreochromis niloticus) alevins in simulated transport

Avaliou-se o efeito do ascorbato sobre o hematócrito e glicemia em alevinos de tilápia nilótica (Oreochromis niloticus) submetidos à simulação de práticas relacionadas ao transporte. Foram utilizadas três dietas experimentais com diferentes níveis de vitamina C (16, 500 e 1000mg de vitamina C/kg), fornecidas durante os 14 dias anteriores à simulação do transporte que se estendeu por 14 horas. O tratamento que continha 16mg de vitamina C/kg foi o que apresentou a glicemia mais elevada logo após a simulação, 108,5mg/dl imediatamente após a simulação e 91mg/dl 12 horas após a simulação. A concentração de 1000mg de vitamina C/kg foi a mais eficiente no controle do aumento da glicemia, 94,6mg/dl imediatamente após a simulação e 74,4mg/dl 12 horas após a simulação. Para a concentração de 500mg de vitamina C/kg foram observados os níveis de 91,4mg/dl imediatamente após a simulação e 103,8mg/dl 12 horas após a simulação. Os valores do hematócrito não apresentaram variação significativa (P>0,05). A suplementação com 1000mg de vitamina C/kg por 14 dias anteriores ao transporte pode ser utilizada de forma profilática em alevinos de tilápia nilótica para amenizar o aumento da glicemia relacionado ao estresse

The effects of ascorbate on the haematocrit and blood glucose level were evaluated in Nile tilapia alevins (Oreochromis niloticus) submitted to a transport simulation. Three experimental diets with different levels of vitamin C (16, 500 and 1000mg/kg) were given for 14 days before the simulation of the transport. The treatment containing 16mg of vitamin C showed the highest level of glucose after the simulation (108.5mg/dl immediately after the transport and 91mg/dl 12 hours after the transport). The vitamin C concentration of 1000mg/kg was the most efficient treatment to control glycemia increases (94.6mg/dl immediately after the simulation and 74.4mg/dl 12 hour after simulation). In the 500mg/kg treatment, the glucose level was 91.4mg/dl immediately after the simulation and 103.8mg/dl 12 hours after the simulation. The haematocrit values did not show any significative variation (P<0.05). The supplementation with 1000mg/kg of vitamin C for a 14 days period can be used in a prophylactic way to soften glycemia increases in Nile tilapia alevins submitted to transport stress

Embryonic and larval development of Jundiá (Rhamdia quelen, Quoy & Gaimard, 1824, Pisces, Teleostei), a South American Catfish

The jundiá (Rhamdia quelen, Quoy & Gaimard) is an endemic South American fish species. Because this species supports cold winters and grows faster during warm months, it has begun to be viewed as an ideal species for fish production in southern South America. In the present study, jundiá oocytes used were obtained by extrusion from females after hormone injection. Soon after hydration, the eggs were transferred to 50 L conic glass incubators, with constant and controlled water influx. Samples of fertilized eggs were transferred to Petri dishes and, examined under a stereoscopic microscope, were spherical, demersal, and non-adhesive with defined perivitelline space and resistant chorion. Cleavage stages occurred during the first 3.5 h. After hatching, larvae were transferred to 200 L glass fiber incubators. First signs of embryo movement were observed 21 h after fertilization; larval eclosion occurred 30.5 h after fertilization. Present findings may provide a basis for studies aimed at determining the complete ontogeny of jundiá and may be useful in eco-toxicological studies.

O jundiá (Rhamdia quelen, Quoy & Gaimard) é uma espécie endêmica da América do Sul. Por ser adaptada ao frio do inverno e ter um crescimento rápido durante os meses quentes, o jundiá é uma espécie adequada para aqüicultura no sul da América do Sul. Muitos aspectos da fisiologia reprodutiva, larvicultura, hematologia, fisiologia da resposta ao estresse, têm sido recentemente estudados. Os ovócitos utilizados neste estudo foram obtidos pela extrusão de fêmeas após indução hormonal. Logo após a hidratação, foram transferidos para incubadoras cônicas de vidro com capacidade para 50 L, com fluxo de água constante e controlado. Amostras de ovos fertilizados foram colocadas em placas de Petri e examinadas através de estereomicroscópio. Os ovos eram esféricos, demersais e não-adesivos, com espaço perivitelino definido e córion resistente. Os estágios de clivagem ocorreram durante as 3,5 primeiras horas. Após a eclosão, as larvas foram transferidas para incubadoras de fibra de vidro de 200 l. Os primeiros sinais de movimento embrionário foram observados 21 h após a fertilização, e a eclosão das larvas ocorreu 30,5 h após a fertilização. Estes resultados podem servir como base para muitos estudos, objetivando o conhecimento da ontogenia completa do jundiá, e para aplicação em estudos ecotoxicológicos.

Desarrollo embrionariolarval y tiempo de metamorfosis del pez tropical Xenomelaniris brasiliensis (Pisces: Atherinidae) / Development of the tropical fish Xenomelaniris brasiliensis (Pisces: Atherinidae) from embryo to larva and time to metamorphosis

Embryoniclarval development, and metamorphosis larval time, were studied in the tropical fish Xenomelaniris brasiliensis. Twenty nine sexually mature specimens were used, 16 females (10.86 ± 1.01 cm and 7.63 ± 2.62 g) and 13 males (10.43 ± 0.57 cm and 6.54 ± 1.44 g) which produced gametes through abdominal massage. Fertilized eggs were spherical (1.18 ± 0.44 mm diameter), greenish, transparent, benthonic and vitelusrich; rugose striated chorion with numerous external filaments randomly distributed and abundant oil globules (0.11 ± 0.07 mm diameter). The embryonic development was finished at 26.36 ± 2.03ºC, 39.67 ± 0.58 PSU and pH 8.30 ± 0.10. Larvae (4.56 ± 0.97 mm total length) hatched at 143 hours and 19 minutes, with vitteline sac vestiges and a single oil globule. The larvae were fed on Brachionus plicatilis and Isochrysis galbana. After the second week Artemia nauplii were added and I. galbana maintained. Flexion started 13 days after larvae hatched (6.10 ± 1.54 mm total length) and was completed 32 days later (11.25 ± 1.87 mm total length) with the hipural complex completely developed. In conclusion, X. brasiliensis showed direct larval development and started larval metamorphosis (13.08 ± 2.07 mm total length) to juvenile 40 days after hatching

Se describe el desarrollo embrionario y larval hasta la metamorfosis de Xenomelaniris brasiliensi. Un total de 29 ejemplares sexualmente maduros, 16 hembras (10.86 ± 1.01 cm y 7.63 ± 2.62 g) y 13 machos (10.43 ± 0.57 cm y 6.54 ± 1.44 g), liberaron sus productos sexuales mediante masaje abdominal. Los huevos fértiles fueron esféricos de 1.18 ± 0.44 mm de diámetro, verdosos, translúcidos, bentónicos, ricos en vitelo, corion rugoso y estriado, con numerosos filamentos coriónicos, distribuidos aleatoriamente por toda la superficie externa y numerosas gotas lipídicas con un diámetro de 0.11 ± 0.07 mm. El desarrollo embrionario se realizó a 26.36 ± 2.03 ºC, 39.67 ± 0.58 PSU y pH 8.30 ± 0.10 eclosionando larvas de 4.56 ± 0.97 mm a las 143 hrs: 19 min, con vestigios del saco vitelino y una gota lipídica interna. Las larvas fueron alimentadas diariamente con Brachionus plicatilis e Isochrysis galbana, a partir de la segunda semana se incorporó nauplios de Artemia, manteniendo la adición diaria de I. galbana. A los 13 días después de la eclosión de larvas (6.10 ± 1.54 mm) se inició la flexión, completándose a los 32 días (11.25 ± 1.87 mm) con un complejo hipural completamente desarrollado. Se concluye que X. brasiliensis presentó desarrollo larval directo, iniciándose la metamorfosis de larva (13.08 ± 2.07) a juvenil a los 40 días de edad

Toxicidade de crioprotetores em embriões de pacu Piaractus mesopotamicus / Cryoprotectant toxicity to pacu embryos Piaractus mesopotamicus

Embriões de pacu Piaractus mesopotamicus foram submetidos a sete tratamentos, com o objetivo de se testar a toxicidade de 2 crioprotetores: glicerol e dimetilsulfóxido (DMSO), e suas associações à sacarose, a temperatura ambiente de 28°C. Nenhum embrião sobreviveu aos tratamentos contendo glicerol. O DMSO foi o crioprotetor que apresentou menor toxicidade aos embriões de pacu.

Fish embryos Piaractus mesopotamicus were submetted to seven treatments to test. the toxicity of two cryoprotectants: glicerol and dimethilfoxidy (DMSO), and its associations with sucrose, at 28°C. There were no survival in treatments containing glicerol. DMSO was the cryoprotectant hat show little toxicity to the embryos.

Light and electron microscopic study of germ cells of the rainbow trout (oncorhynchus mykiss)

El objetivo de este trabajo es describir las características morfológicas de las células germinales de la trucha arcoiris Oncorhynchus mykiss, durante los estados pregonádico, gonádico y gónada tempranamente diferenciada. Las células germinales primordiales se identificaron en los embriones de 11-35 días postfecundación (125-300ºD), correspondiendo al estado pregonádico. Son células grandes con un núcleo voluminoso y pálido. El citoplasma tiene un volumen mínimo y aparece homogéneo con ribosomas y mitocondrias distribuidas regularmente. También se presentan gránulos oscuros, semejantes a inclusiones vitelinas. El esbozo gonádico se forma a los 40 días postfecundación (400ºD) y la diferenciación de la gónada, en ovario o testículo, se inicia a los 150 días (1500ºD). La estructura ovárica, al inicio de la diferenciación, presenta oocitos rodeados por células prefoliculares. El testículo tempranamente diferenciado se identifica por la presencia de acúmulos de espermatogonias dispuestos en cistos. El estudio que se presenta contribuye a mejorar la caracterización de las células germinativas de la trucha arcoiris y también entregar información respecto a la cronología de los estados principales de la diferenciación gonadal, en embriones y alevines mantenidos a una temperatura constante de 10ºC

On the reproduction of brazilian fishes: XIII. Scanning electron microscopic study of the rhythin of development in oocyte of the lambari (Astyanax bimaculatus) Reinhardt 1874 (Pisces, Characidae)

A oogênese do lambari Astyanax bimaculatus foi dividida em três grandes fases: 1) fase primária de crescimento - caracterizada pelo aumento mitótico do número de oogônias, sendo constituída pelas sub-fases cromatina-nucléolo, perinucleolar inicial e perinucleolar avançada; 2) fase vitelogênica - que envolve duas sub-fases: a de vesícula vitelínica contendo vesícula de glicoproteínas e a de vitelogênese contendo grânulos de glicoproteínas; 3) fase de maturaçäo - caracterizada pela formaçäo de oócitos maduros