Showing papers by "University of Costa Rica published in 1984"

Diversity of soft-bottom benthos in a tropical estuary: Gulf of Nicoya, Costa Rica

Abstract: The community structure of soft-bottom infauna is described for the Gulf of Nicoya, Costa Rica, Central America, with special reference to the relationship between diversity and a tropical estuary. Of the 205 species of invertebrates collected in July, 1980, polychaetes comprised 58.6% by number of species and 68.1% by number of individuals. Density ranged from zero to 8 744 m-2 with a mean of 1 269 m-2 per station, and biomass ranged from zero to 10.986 g m-2 with a mean of 2.010 g m-2. Numerical analysis indicated considerable faunal homogeneity, characterized by polychaetes. Five major polychaete feeding guilds were recognized. From measures of diversity we concluded that the soft-bottom community of the Gulf of Nicoya was not rich for a tropical estuary. Physical processes (riverine runoff and frontal systems) mainly influenced community structure and function in the lower Gulf whereas biological processes (predation) seemed to prevail in the upper Gulf.

Pérdida de zooxantelas y muerte de corales y otros organismos arrecifales en el Caribe y Pacífico de Costa Rica

Abstract: Since June, 1983 many corals and other reef organisms on the Caribbean and Pacific coasts of Costa Rica were observed to be bleached, due to loss of their symbiotic zooxanthellae. Some of the corals recovered by the end of October while others died. Observations, mainly at Parque Nacional Cahuita, Limon (Caribbean coast), were not conclusive as lo the causative agent for this massive death, High water temperatures, combined with other environmental stresses, could be responsible, since in June, 1983, temperatures of 33 and 35 °C were recorded at Cahuita. Apparently the boring sponge Cliona caribbea profited by the massive death of these corals.

Hydrogen atom in the phase-space formulation of quantum mechanics

Abstract: Using a coordinate transformation which regularizes the classical Kepler problem, we show that the hydrogen-atom case may be analytically solved via the phase-space formulation of nonrelativistic quantum mechanics. The problem is essentially reduced to that of a four-dimensional oscillator whose treatment in the phase-space formulation is developed. Furthermore, the method allows us to calculate the Green's function for the H atom in a surprisingly simple way.

Mecanismo de acción de miotoxinas aisladas de venenos de serpientes

Abstract: Biochemically and pharmacologically, myotoxins isolated from snake venoms can be placed in four main groups: myolaxic phospholipases A, low molecular weight basic toxins, cardiotoxins, and hemorrhagic myotoxins. The myotoxic phospholipascs A notexin, taipoxin, crotoxin, and Bothrops asper myotoxin induce muscle necrosis by first affecting the integrity of the plasma membrane, thereby inducing a calcium influx that culminates in cell death. The small basic myotoxin crotamine acts on the voltage-sensitive sodium channels of skeletal muscle sarcolemma, inducing a sodium influx which is responsible for depolarization and contraction of skeletal muscle, as well as for vacuolization of sarcoplasmic reticulum. Cardiotoxins are basic membrane-active polypeptides that disorganize the structure of membranes; the myotoxic activity of cardiotoxins results from their ability to disrupt skeletal muscle sarcolemma. Finally, two hemorrhagic toxins (hemorrhagic toxin b and viriditoxin) are myotoxic; apparently, they induce myonecrosis secondarily to ischemia which develops in muscular tissue as a consequence of the hemorrhagic action of these toxins.

Growth and development of the portunid crab callinectes arcuatus ordway: zoeae, megalopae, and juveniles

Abstract: Larvae of the blue crab Callinectes arcuatus were reared in the laboratory through eight zoeal and one megalopal stage. The number of maxilliped setae characterizing each zoeal stage was identical to that for Callinectes sapidus. Survival and rate of development of the zoeae and megalopae was high compared to published results for C. sapidus. Mean duration of development of C. arcuatus from hatching to Crab Stage 1 was 69.3 days and survival was 16.2%. Megalopae surviving to Crab Stage 1 were reared to Crab Stage 7. Linear increments in carapace width were measured at each molt, and the total time of development from Crab Stage 1 to maturity was calculated to be 301 days.

Composition and nutritive value of pejibaye ( Bactris gasipaes ) in animal feeds

Abstract: Nutritive assessment of pejibaye (Bactris gasipaes) meals included proximal composition of the lipid and nitrogenous fractions. Caloric values obtained as true metabolizable energy (TME) indicate that the pejibaye has a higher content of energy than corn and that it is not necessary to separate the seeds from the fruits in animal feeds; the level of indispensable aminoacids is considerably low, especially methionine, which is lower than in corn; thin layer chromatography shows that most of the free fatty acids are present in a ratio of 2:1 in unsaturated to saturated acids. The predominant fatty acids in whole pejibaye meal are oleic and palmitic acids with adequate levels of linoleic acid. Saturated fatty acids are predominant in the seed, with a very high content of lauric and myristic acids.

El Arrecife Coralino del Parque Nacional Cahuita, Costa Rica

Abstract: The coral reef at Parque Nacional Cahuita, Limon, Costa Rica, is a reef under stress due to siltation. The amount of suspended sediments is high and resuspension of bottom sediments is also high. Growth rates of corals, live coral coverage and diversity were low. Colonies are generally larger than in other areas studied, and recruitment of planulae seems to be low. Most of the corals present are good at rejecting sediments and morphologies of some change to better resist the sediments (vertical fronds of Agaricia agaricites ) or to receive more light (shingles of Montastrea annularis and Porites astreoides ). Analyses of the currents and the type of minerals present in the noncarbonate fraction of the sediments at the reef point to Rio La Estrella as the source of sediments. The amount of sediments carried by this river has probably increased recently as a result of watershed deforestation. The problem of siltation in reef environments is bound to increase as new areas in the tropics are being developed. Sediments affect both the individual coral and the coral community. Whether a reef is (or was) under stress due to siltation, can be determined by analyzing the following: growth rates of the corals, amount of trapped sediments in the skeletons, live coral coverage, species composition and diversity, and morphologies.

Occurrence of the bat tick ornithodoros (alectorobius) kelleyi cooley & kohls (acari : argasidae) in costa rica and its relation to human bites

Abstract: Varias personas de dos localidades en Costa Rica (San Rafael de Coronado, 1510 m y Dulce Nombre de Tres Rios, 1145 m, de las Provincias de San Jose y Cartago respectivamente), fueron picadas por garrapatas, subsecuente mente identificadas como Ornithodoros (Alectorobius) Kelleyi , argasidos asociados con murcielagos. En los aticos de las casas de los pacientes, se encontraron, en el guano, adultos, larvas, ninfas y exuvias. Como no se ha informado de argasidos adultos para Costa Rica, se establecio una colonia de laboratorio para su estudio taxonomico, y para observar la biologia de las garrapatas y su asociacion con los murcielagos, en este caso particular, Molossidae y Vespertilionidae, ambas familias son especies insectivoras. La colonia se establecio usando tubos de vidrio con yeso en el fondo para dar la humedad adecuada. Tanto el ultimo estadio ninfal como los adultos se alimentan facilmente de ratones lactantes y en condiciones de oscuridad. Los periodos de alimentacion duran de 20 a 40 minutos, flotandose ademas, abundante produccion de liquido coxal. La oviposicion ocurre entre los 1 4 a los 27 dias despues de la alimentacion del adulto. El estudio de los cortes histologicos de piel de los ratones, muestra lesiones hemorragicas locales y fuerte edema alrededor de los sitios de las picadas, lo que corrobora la fuerte accion toxigenica de estos argasidos. Se hace una comparacion entre las medidas de las estructuras mas comunes usadas en la taxonomia de larvas argasidas, tales como la longitud y ancho del cuerpo, hipostoma, basis capituli, palpos, tarsos 1 y placa dorsal, tipo de denticion, longitud y distancia de PH 1 y PH 2 . Tal estudio no revelo diferencias importantes entre especimenes completos y pieles de los mismos. Este hallazgo es importante si se considera que dentro de los habitos de los argasidos, es mas 1 0 1 facil encontrar en el habitat las exuvias y no los ejemplares vivos.

Additions to the known anomuran fauna of el salvador, central america (crustacea: decapoda)

Abstract: Twenty-nine species of the Infraorder Anomura were identified from invertebrate material recently collected from the coastal waters of El Salvador. Only 17 species that represent significant finds are treated here in detail; 3 species belonging to the genera Clibanarius, Paguristes, and Isocheles are undescribed, the ranges of 6 species are extended to El Salvador, and 7 other widely ranging species are new to the country. The remaining 12 species are listed with habitat information. A range map of the 37 known anomuran species of El Salvador and illustrations of the undescribed species are included.

Dermatofitosis por Aphanoascus fulvescens

Abstract: Aphanoascus fulvescens was isolated from lesions resembling a dermatophyte infection in a 45-year-old woman who had used steroid cream for several months to treat a dermatosis of the neck. Treatment with griseofulvin and tolnaftate cured the lesions in 6 weeks. The microscopic characteristics of the isolate and its size differed slightly from those described by several other authors, and bore a closer resemblance to isolates previously described from Australia and New Guinea.

Seasonal abundance of brachyuran crab larvae in a tropical estuary: Gulf of Nicoya, Costa Rica, Central America

Abstract: Brachyuran crab larvae were sampled approximately monthly at four stations in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Costa Rica, Central America. The gulf was divided into two regions based on physical and chemical characteristics. Larvae were identified to five families: Ocypodidae, Pinnotheridae, Portunidae, Majidae, Xanthidae. The abundance and distribution of these taxa were similar to that found in temperature estuaries of North America. Ocypodids, pinnixids, and xanthids were most common in the estuarine upper-gulf region while portunids were more common in the lower gulf. Majids were found in small numbers in the lower gulf. Only the ocypodids showed a consistent pattern in vertical distribution; larvae of this taxon were always more common in surface water. There was no consistent pattern in the seasonal abundance of the various taxa when compared among stations.

Ecological assessment of finfish as indicators of habitats in the Gulf of Nicoya, Costa Rica

Abstract: Trawl samples of demersal fish populations within the Gulf of Nicoya, Costa Rica were conducted during February and July, 1979 and April, 1980 in an attempt to define basic abundance, diversity and distributional patterns. Seventeen day and three night samples produced 6 441 fishes of 107 species during the February cruise. Twenty day and two night samples produced 9 220 individuals of 131 species during the July cruise. Twenty day samples produced 14 151 individuals representing 125 species taken during the April cruise. A total of 214 species were collected during this study. The Gulf may be divided into three zones on the basis of the physical characteristics of the stations (water temperature, dissolved oxygen, salinity, depth and distance from the mouth of the Gulf). Few changes in the position of these zones occurred during the study period indicating a relatively stable estuarine configuration from a biological perspective. The Gulf of Nicoya area is under the influence of a wet and a dry season. No significant seasonal changes in the number, biomass, percent occurrence, diversity of partitioning by size class of fishes were observed. Two major types of fish distributional patterns were observed. Several species were ubiquitous and were found throughout the Gulf in varying abundances. Other species were restricted to either the upper or lower Gulf. Dominant groups in the upper Gulf include the sciaenids, sea catfishes (Ariidae) and flatfishes (Soleidae, Cynoglossidae andSyacium ovale). These fishes tend to inhabit the warmer, shallower, less saline waters of the upper Gulf. Flounders (bothidae), gobies (Bollmannia spp.), morays and congers (Hildebrandia nitens, Priodonophus equatorialis andMuraenesox coniceps) and several other species dominated the deeper, cooler, more saline lower Gulf.

Estudios cariológicos de cinco especies de serpientes costarricenses de la familia Colubridae

Abstract: The karyotypes of five species of colubrid snakes from Costa Rica are as follows: Imantodes cenchoa and Drymobius margaritiferus have a diploid number of 36, with 16 macro- and 20 microchromosomes. The fourth pair is heteromorphic in females of I. cenchoa, with a metacentric Z and a submetacentric W chromosomes. Karyotypes of Erythrolampius bizonus and Leimadophis epinephalus have 28 chromosomes, without a clearcut separation between macro- and microchromosomes. In the case of E. bizomus, the fourth pair contains the sex chromosomes Z and W, both are submetacentric, but the W is smaller. Xenedon rabdocephalus has a diploid number of 34 chromosomes (22 macro- and 12 microchromosomes); pair 3 is heteromorphic in females, with a submetacentric Z and a smaller metacentric W. The karyotype of X. rabdocephalus may be derived from a primitive karyotype by means of reduction in the number of microchromosomes and centric fissions of two pairs of metacentric autosomes.

Determinación de plaguicidas organoclorados en leche materna en Costa Rica

Abstract: DDT and DDE were detected in the milk of 51 nursing mothers in Costa Rica. In the provinces of Puntarenas, Guanacaste and Limon, where a campaign against malaria took place during the last three decades and where crops are intensively sprayed, the amount of total DDT ranges from 0.12 to 2.60 ppm (mean 1.27 ppm), comparatively, the data of total DDT yielded an average of 0.11 ppm (range 0.01-1.22 ppm) in the provinces of San Jose, Heredia and Cartago, not so intensively exposed to pesticides. Higher concentrations of the metabolite DDE in 100% of the samples indicated chronic contaminations.

Biología del género Melaloncha (Phoridae) moscas parasitoides de la abeja doméstica ( Apis mellifera L.) en Costa Rica

Abstract: En Costa Rica las moscas Melaloncha (ocho especies aproximadamente) parasitan a la abeja domestica, durante la epoca lluviosa, especialmente en el Valle Central, Turrialba, Puriscal y la zona de Orotina. La magnitud del dano causado por esta mosca es de importancia economica en los apiarios. La copulacion de estas moscas ocurre alrededor de las colonias de abejas o en algunas flores que son tambien visitadas por las abejas. La oviposicion de Melaloncha ocurre cuando las abejas se estan aproximando a la entrada en la colmena, estan paradas en la entrada o cuando estan en las flores. Posiblemente las moscas introducen el ovipositor a traves de las membranas intersegmentadas del abdomen. Los primeros estadios de la larva se desarrollan en el abdomen. Cuando la abeja cae y se muere, la larva migra hacia el torax donde termina su desarrollo durante 3 dias y pupa. El periodo de pupa fue entre 28 y 36 dias. La relacion entre machos y hembras fue practicamente de 1 : 1. Se encontro obreras de Bombus mexicanus Cresson y de Melipona faciata Latreille parasitadas por Melaloncha ; es posible que otras especies de Apidae sean tambien sus hospederos naturales.

Criptosporidiosis en niños de Costa Rica: estudio transveral y longitudinal

Abstract: The present report is a systematic study of children, with and without diarrhea from Costa Rican metropolitan areas and southern rural higlands. Children were observed, respectively, at emergencies, Hospital Nacional de Ninos, and in a field station in Puriscal; urban children were studied vertically, rural children were observed prospectively (cohort study). Cryptosporidium sp. was found in 4.3% of the cases of diarrhea; diahrrea was generally severe in urban children, but mild in the rural. Infection was detected in urban children less than one year of age: contrasting, no rural infants were found infected, which might be related to breast-feeding, since Puriscal infants were intensively breast-fed for several months, while many urban infants were not breast-fed or were weaned earlier. Cryptosporidium sp. appeared during the warm, rainy and humid months of May through August, when the coccidium was associated with 14.8% of the urban and 15.4% of the rural diarrheas. AH urban cases presented dehydration which was corrected with oral rehydration salt therapy, and occasionally with intravenous fluids; dehydration was not common in the rural cases.

Sorbitol dehydrogenase deficiency in several pig tissues: potential implications for studies of experimental diabetes

Abstract: Screening for red blood cell sorbitol dehydrogenase deficiency in 12 different mammalian species was performed. A wide inter-species variability in red cell sorbitol dehydrogenase with a virtually complete deficiency in pigs was observed. Aldose reductase and sorbitol dehydrogenase activities in 12 different pig tissues also were measured. Aldose reductase activity was present in all the tissues studied, whereas organ specificity for sorbitol dehydrogenase was observed. Sorbitol dehydrogenase activity was not detectable in lenses, among other tissues, making the pig a potential model for studies in experimental diabetes, particularly for the investigation of sorbitol dehydrogenase deficiency as a risk factor in the development of cataracts.

Two altemative strategies for spider egg parasitoids

Abstract: Regulation of intensity of parasitism in spider-egg parasitoids is more complex than in mast parasites, since spider eggs are tightly packed in sacs and factors controlling proportion of eggs parasitized per sac also regulate population densities. Both microhymenopterans Baeus achaearaneus (Scelionidae) and Tetrastichus sp. (Eulophidae), are egg parasitoids of the spider Achaearanea tepidariorum in Costa Rica. B. achaearaneus tends to locate a large number of sacs and to parasitize only a small proportion of eggs in each; Tetrastichus sp. locates a small proportion of the sacs available (typical of all parasites studied heretofore), but maximizes the utilization of eggs in each sac. The latter is intrinsically superior whenever both species attack the same sac (multiple parasitism).

Desarrollo larval de Ozius verreauxii Saussure (Brachyura: Xanthidae) en el laboratorio

Abstract: Larvae of the xanthid crab Ozius verreauxii were reared in the laboratory from hatching to megalopa. Complete larval development required about 15 days under culture conditions of 27 °C and 32 o/oo salinity. High survival was observed through the first two zoeal stages with an increase in mortality during zoeal stages III and IV.