Browsing Artículos científicos by Issue Date
Now showing items 21-40 of 551
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Ciclo anual del fitoplancton en el lago de Rio Cuarto, Costa Rica
(Universidad Nacional [Costa Rica], 1989-01-01)El ciclo anual de fitoplancton y nutrientes (nitratos y ortofosfatos) del Lago Río Cuarto, Costa Rica, ha sido estudiado desde febrero de 1984 hasta marzo de 1985. Las muestras de agua se obtuvieron con un muestreador ... -
Composición, diversidad y abundancia de peces en el embalse Arenal, Guanacaste, Costa Rica
(Universidad de Costa Rica (Costa Rica), 1989-11-01)The abundance, species diversity. richneiS, dominance, evenness and similarity índices of the fish cornmunities at two stations in the Arenal Reservoir, Guanacaste, Costa Rica, were estimated between April 1984 and April ... -
Variación estacional en el Lago de Rio Cuarto, provincia de Alajuela, Costa Rica. II Distribución estacional del zooplancton
(Universidad Nacional [Costa Rica], 1990-01-01)En el lago de Río Cuarto, provincia de Alajuela, Costa Rica, durante los meses comprendidos entre febrero de 1984 y marzo de 1985, se realizaron estudios sobre la composición de la comunidad zooplanctónica, las variaciones ... -
Diferencias morfométricas por sexo de tres especies del genero Opisthonema (Psices: Clupeidae) de la Costa del Pacifico, Costa Rica
(Universidad Nacional [Costa Rica], 1990-01-01)Se comparan algunas variables morfométricas en los dos sexos de tres especies de Opisthonema (O. libertate, O. medirastre y O. bullerri) provenientes de las costa Pacífica de Costa Rica. Las hembras como los machos revelaron ... -
Citotaxonomía comparativa de tres especies de Cichlasoma (Pisces: Cichlidae) nativas de Costa Rica
(Universidad de Costa Rica, 1991)The karyotype oí three species oí CichlasofM: C. dOllii, C. managwmse and C. friedrichstali were studied. The number of diploid chromosomes is 2n=48 in the fust two species. Their karyotypes are composed of four pairs ... -
Intensive Rearing of Juveniles of cichlasoma managuense (Günther 1869) in recirculated systems
(Universidad Nacional, Costa Rica, 1991-01-01)The growth performance of guapote juveniles in recirculated systems from spawning to a mean weight of about 3 gramms is described. Culture began with a 15 days nursing phase with either first instar-nauplii or fresh ... -
Fenología y desarrollo de las agallas de las ramas del güisaro (Psidium guineense Swartz) (Myrtaceae) y su relación con varias especies de Microhimenopteros en Heredia, Costa Rica.
(Universidad Nacional, Costa Rica, 1991-01-01)En una población natural de güísaro (Psidium guineense), en Barva de Heredia, se estudió el desarrollo de las agallas de las ramas y la fenología de cuatro especies de micro himenópteros emergidos de ellas, desde abril de ... -
Growth performance of Colossoma macropomum (Cuvier) juveniles at different feed rations
(Wiley & Sons, 1992)Growth performance, feed utilization and changes in body composition of Colossoma macropomum (Cuvier) juveniles — in the weight range 2 to 200 g — fed an artificial high protein diet, have been analysed against feed ... -
Utilización de variables morfometricas para explicar el comportamiento del peso fresco y eviscerado en tres especies de peces del género opisthonema. (Pisces: Clupeidae)
(Universidad Nacional, Costa Rica, 1992-01-01)Se trabajó en la búsqueda del mejor modelo estadístico que explique el peso fresco y eviscerado, utilizando las variables morfométricas más sobresalientes. Mediante el análisis de varianza, se comprobó que hay diferencia ... -
Preliminary evaluation of eyestalk ablation and thoracic ganglion importation on spermatophore quality and molting of male Penaeus vannamei
(Universidad Nacional, Costa Rica, 1992-01-01)Males of Penaeus vannamei (mean weight = 25.05 ± 1.89 g), selected from a commercial semi-intensive pond, selected form a commercial semi-intensive pond, were used to study the effect of thoracic ganglion implantation on ... -
The effect of high rearing densities on the growth of juveniles of the cichlid, cichlasoma managuense
(Universidad Nacional, Costa Rica, 1992-01-01)The effect of high density culture on the growth of juvenile jaguar cichlids was investigated. Mean growth rate decreased with density, while the growth rate of the largest fishes was not affected. Reduction in mean growth ... -
Growth of Jaguar Cichlid (Cichlasoma managuense) juveniles at different oxygen levels
(Universidad Nacional, Costa Rica, 1992-01-01)The dependence of growth on the dissolved oxygen level was analyzed un juveniles of the guapote tigre, Cichlasoma managuense, in a recirculated system. The guapote tigre is relatively tolerant to low oxygen levels, averaging ... -
Development and Deterioration of Spermatophores in Pond-Reared Penaeus vannamei
(World aquaculture society, 1993)Spermatophore deterioration in pond-reared Penaeus vannamei was studied, and spermatophore quality was evaluated and improved. Sperm production of males collected from grow-out ponds was increased by two techniques: ... -
Larvae of the Costa Rican Hetaerina (Odonata: Calopterygidae) with comments on distribution
(Royal Entomological Society, 1993)The larvae of seven of the nine Costa Rican species of Hetaerina (H.capitalis, H.cruentata, H. fuscogutfata, H. majuscula, H. miniata, H. occisa and H. titia) were identified by matching their Cellulose Acetate Gel ... -
Interaction of bacteria and male reproductive system blackening disease of captive Penaeus setiferus
(Elsevier, 1993)The genital apparatus of male penaeid shrimp, Penaeus sett’ferus, blackens with resulting detrimen tal effects ton mating for production of larvae when animals are kept in controlled maturation/repro duction situations. A ... -
Utilización de tres medios orgánicos para la germinación in vitro de semillas de guaria morada, Cattleya skinneri (Bateman)
(Universidad Nacional, Costa Rica, 1993-01-01)Con el fin de determinar diferencias en la germinación de semillas Cattleya skinneri, ocasionadas por diversos medios de cultivo, en condiciones “in vitro”, fueron evaluados cuatro medios (tratamientos: tres de origen ... -
Reproducción del camarón Penaeus occidentalis (Decapoda: Penaeidae) en el Golfo de Nicoya, Costa Rica
(Universidad de Costa Rica (Costa Rica), 1993-12-01)Del 26 de junio al 27 de julio de 1992, se observó la reproducción natural de Penaeus occidentalis cerca de la playa Curazao, Isla Chira, Golfo de Nicoya, Costa Rica. Este es el primer informe de reproducción de un camarón ... -
Biometry of Modiolus capax (Bivalvia: Mytilidae) in Playa Ocotal, Guanacaste, Costa Rica
(Universidad de Costa Rica, 1994)155 specirnens of mussels (Modiolus capax) were gathered during March 1993 in a subtidal hed, located in northern Ocotal, Guanacaste, Costa Rica. For each individual in the randon sample, shell length, breadth and height ... -
Effects of the protein: energy ratio in isocaloric diets on the growth of Cichlasoma managuense (Gunther 1869)
(Wiley & Sons, 1994)A feeding experiment was conducted to evaluate the growth of tiger guapote, Cichlasoma managuense (Gunther), fed on isocaloric diets with varying proteinxnergy ratios. The relative metabolic growth rate increased with ... -
Environmental impacts of nitrification and nitrate adsorption in fertilized andisols in the Valle Central of Costa Rica
(Williams & Wilkins, 1994)A major scientific challenge for modern agriculture is control of off-site effects on the water resource. In the Valle Central of Costa Rica, coffee plantations may leach fertilizer-derived (Equation presented) to groundwaters, ...