oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 37 )

2018 ( 74 )

2017 ( 54 )

2016 ( 87 )

Custom range...

Search Results: 1 - 10 of 44614 matches for " Alvaro Morales- Ramírez "
All listed articles are free for downloading (OA Articles)
Page 1 /44614
Display every page Item
Morfología y taxonomía de los Mesocyclops (Crustacea: Copepoda: Cyclopoida) de México.
Alvaro Morales Ramírez
Revista de Biología Tropical , 2005,
Abstract:
Composition, abundance and distribution of macrozooplankton in Culebra Bay, Gulf of Papagayo, Pacific coast of Costa Rica and its value as bioindicator of pollution
Bednarski,Melinda; Morales-Ramírez,Alvaro;
Revista de Biología Tropical , 2004,
Abstract: the abundance, distribution and composition of the macrozooplankton of culebra bay, costa rica (10o 38? n - 85o 40? w) were studied at four stations throughout the dry (february - may) and rainy (september - november) seasons of 2000. the samples were collected at two-week intervals using a 500μm mesh net with a 0.5 m diameter opening. copepods (23-31%) and ostracods (20-34%) were predominant throughout the year, followed by cladocerans (2.5-14%), zoea (6.6-9.5%), and siphonophores (2.5-7.2%). high densities of zooplankton were obtained in february and march with peak abundance on march 18. the lowest densities were observed on september 3 and november 5. significant differences in abundances at each station were observed for the groups acartia tonsa (copepoda), ctenophora, medusae, ostracoda, zoea, and amphipoda. comparison of the dry and rainy seasons revealed significantly higher zooplankton abundance in the dry season and copepod domination of all stations; during the rainy season ostracods dominated the off-shore areas. zooplankton abundance and distribution are influenced by upwelling, which occurs during the dry season in culebra bay
Composition, abundance and distribution of macrozooplankton in Culebra Bay, Gulf of Papagayo, Pacific coast of Costa Rica and its value as bioindicator of pollution
Melinda Bednarski,Alvaro Morales-Ramírez
Revista de Biología Tropical , 2004,
Abstract: The abundance, distribution and composition of the macrozooplankton of Culebra Bay, Costa Rica (10o 38’ N - 85o 40’ W) were studied at four stations throughout the dry (February - May) and rainy (September - November) seasons of 2000. The samples were collected at two-week intervals using a 500μm mesh net with a 0.5 m diameter opening. Copepods (23-31%) and ostracods (20-34%) were predominant throughout the year, followed by cladocerans (2.5-14%), zoea (6.6-9.5%), and siphonophores (2.5-7.2%). High densities of zooplankton were obtained in February and March with peak abundance on March 18. The lowest densities were observed on September 3 and November 5. Significant differences in abundances at each station were observed for the groups Acartia tonsa (Copepoda), Ctenophora, Medusae, Ostracoda, Zoea, and Amphipoda. Comparison of the dry and rainy seasons revealed significantly higher zooplankton abundance in the dry season and copepod domination of all stations; during the rainy season ostracods dominated the off-shore areas. Zooplankton abundance and distribution are influenced by upwelling, which occurs during the dry season in Culebra Bay La abundancia, distribución y composición del macrozooplancton fue estudiada en bahía Culebra Costa Rica (10o 38’ N and 85o 40’ W) en cuatro estaciones durante la época seca (Febrero-Mayo) y lluviosa (Setiembre - Noviembre) del a o 2000. Las muestras fueron colectadas en intervalos de dos semanas usando una red de 500μm de poro y 0.50-m de diámetro. Copépodos (23-31%) y ostrácodos (20-34%) fueron predominantes através del a o, seguidos por los cladóceros (2.5-14%), zoea (6.6-9.5%), y sifonóforos (2.5-7.2%). Altas densidades de zooplancton fueron obtenidas en Febrero y Marzo, con un pico el 18 de Marzo. Las más bajas densidades fueron observadas el 3 de Septiembre y 5 de Noviembre. Se observaron diferencias significativas en las abundancias en cada estación para los copépodos de la especie Acartia tonsa, los grupos Ctenophora, medusae, Ostracoda, zoea y Amphipoda. Comparando las estaciones seca y lluviosa, significativamente más altas densidades fueron obtenidas en todas las estaciones en la época seca; durante la época lluviosa los ostrácodos dominaron las áreas externas. La abundancia y distribución del macrozooplancton son influenciadas por el afloramiento, el cual ocurre durante la época seca en Bahía Culebra
Nuevo registro de Acartia (Planktacartia) negligens (Copepoda, Calanoida) en el Pacífico Tropical Oriental
Eduardo Suárez-Morales,Alvaro Morales-Ramírez
Revista de Biología Tropical , 2001,
Abstract:
Trophic planktonic dynamics in a tropical estuary, Gulf of Nicoya, Pacific coast of Costa Rica during El Ni?o 1997 event
Brugnoli-Olivera,Ernesto; Morales-Ramírez,Alvaro;
Revista de biología marina y oceanografía , 2008, DOI: 10.4067/S0718-19572008000100008
Abstract: the trophic dynamics of the plankton from the gulf of nicoya, a tropical estuary in the pacific coast of costa rica, was conducted during dry and rainy seasons of 1997. water temperature, oxygen and salinity were measured at two different light penetration depths. inorganic nutrients, total and nannophytoplanktonic chlorophyll a were determined at each depth and additional samples were taken for phytoplankton taxonomic work. oblique zooplankton hauls were done and abundance, composition and dry weight of zooplankton were determined. indirect grazing rate estimate was calculated using the pigment budget. the study period coincided with an el ni?o event detected in the punta morales zone and reflected by a change in the physico-chemical water characteristics. some nutrient concentrations were correlated to the salinity, and significant differences were observed between the transition and rainy seasons in the phytoplankton biomass of the two fractions. a total of 43 phytoplankton taxa were identified and flagellates, centric and pennate diatoms represented 90% of the total phytoplankton abundance. in the zooplanktonic samples, copepods were the most abundant group and acartia lilljeborgii, pseudodiaptomus sp. and paracalanus parvus were the dominant herbivores; dry weight mean values of herbivorous copepods were between 0.6 and 50 mg m-3. grazing rate showed a mean of 0.67 ± 0.83 d-1. this study showed a seasonal behavior with changes in nutrient concentrations, availability of phytoplankton and rising temperatures through el ni?o. predation and grazing pressure produced changes in the structure of plankton (phyto and zooplankton) populations in the internal zone of gulf of nicoya
Presencia y patrones de comportamiento del delfín manchado costero, Stenella attenuata (Cetacea: Delphinidae) en el Golfo de Papagayo, Costa Rica
May-Collado,Laura; Morales Ramírez,Alvaro;
Revista de Biología Tropical , 2005,
Abstract: occurrence and behavioral patterns of the spotted coastal dolphin stenella attenuata (cetacea: delphinidae) in the gulf of papagayo, costa rica. dolphins are characterized by a significant behavioral versatility, which allows them to respond to environmental seasonality. seasonal variation in dolphin behavior in tropical waters is not well known. stenella attenuata graffmani is a resident dolphin in the clearly defined seasonal gulf of papagayo, costa rica, and we studied if dolphin group size, occurrence and behavioral patterns were associated with season and time of day in the gulf. using strip transects we surveyed two locations for three consecutive years.school size ranged from 1 to 50 individuals, mean group size was 10.16 (sd =9.61) individuals. overall, foraging activities were the most frequent, followed by social interactions and travel. from 6:00 am to 9:00 am we mostly observed social interactions, followed by feeding-socializing (9:00 am-12:00 pm) and feeding exclusively (12:00 pm-3:00 pm). social activities intensified afterwards (3:00 pm-6:00 pm). behavior and gulf seasonality were associated (c 2 =90.52,gl =6,p<0.05,n =99). in the dry season (december- april) feeding predominated over other activities, but socializing was more frequent in the early rainy season (may-july). larger groups (mean 12 dolphins) forage actively; smaller groups (mean 6 dolphins 6.51 ± 5.12) foraged more passively. seasonal variation in dolphin activities are likely to be associated with food availability, as observed in the high number of groups involved in foraging behaviors, and a high investment in foraging activities during the dry season. rev. biol. trop. 53(1-2):265-276.epub 2005 jun 24
Presencia y patrones de comportamiento del delfín manchado costero, Stenella attenuata (Cetacea: Delphinidae) en el Golfo de Papagayo, Costa Rica
Laura May-Collado,Alvaro Morales Ramírez
Revista de Biología Tropical , 2005,
Abstract: Los delfines se caracterizan por una increíble versatilidad, la cual les ha permitido responder a los cambios estacionales de su ambiente. Dicha variación estacional en los patrones de comportamiento se considera poco conocida en delfines que habitan aguas tropicales. El delfín manchado (forma costera) Stenella attenuata graffmani, parece ser la única especie de cetáceo residente en el Golfo de Papagayo, área que se caracteriza por una estacionalidad muy bien definida. El objetivo de este trabajo es determinar si esta estacionalidad influencia el tama o del grupo, la presencia y patrones de comportamiento de esta especie de delfín en el golfo. Usando transectos en banda se recorrieron dos localidades del Golfo de Papagayo. El tama o del grupo varío de uno a 50 individuos, con una media de 10.16 (DS =9.61). Las actividades alimentarias fueron más intensas que las interacciones sociales y de desplazamiento, las cuales siguieron un ordenamiento diario y estacional. Se describieron dos técnicas principales de forrajeo las cuales parecen estar asociadas con el tama o del grupo y localidad dentro del golfo. La variación diaria en los patrones de comportamiento parecen estar relacionados con la disponibilidad, distribución, y arreglo espacial de las presas. De igual manera, la variación estacional de estas actividades probablemente esta asociada por la disponibilidad de alimento, tal como ha sido observado en un mayor número de grupos y una mayor inversión de tiempo en actividades de alimentación durante la época seca y finales de las lluvias Occurrence and behavioral patterns of the spotted coastal dolphin Stenella attenuata (Cetacea: Delphinidae) in the Gulf of Papagayo, Costa Rica. Dolphins are characterized by a significant behavioral versatility, which allows them to respond to environmental seasonality. Seasonal variation in dolphin behavior in tropical waters is not well known. Stenella attenuata graffmani is a resident dolphin in the clearly defined seasonal Gulf of Papagayo, Costa Rica, and we studied if dolphin group size, occurrence and behavioral patterns were associated with season and time of day in the gulf. Using strip transects we surveyed two locations for three consecutive years.School size ranged from 1 to 50 individuals, mean group size was 10.16 (SD =9.61) individuals. Overall, foraging activities were the most frequent, followed by social interactions and travel. From 6:00 AM to 9:00 AM we mostly observed social interactions, followed by feeding-socializing (9:00 AM-12:00 PM) and feeding exclusively (12:00 PM-3:00 PM). Social activities
Comportamiento de las masas de agua en el Golfo Dulce, Costa Rica durante El Ni?o (1997 - 1998)
Quesada-Alpízar,Marco A; Morales-Ramírez,Alvaro;
Revista de Biología Tropical , 2004,
Abstract: in order to understand the vertical distribution of planktonic organisms in the oceans, it is important to consider a number of factors. including oceanic circulation patterns, the vertical structure of the water column and the vertical position of the thermocline. this study examines the hydrography of golfo dulce, a tropical fjord -like embayment in the eastern tropical pacific, and the influence of the 1997-1998 enso on the system. five sampling stations were selected and visited once a month for two years in order to obtain vertical profiles of temperature (oc), salinity (?) and dissolved oxygen (mg o2 /l). results show a strong vertical stratification of the water column associated to the morphology of golfo dulce?s basin and to the effects of enso. moreover, the existence of significant differences between the hydrographic characteristics of the inner and outer parts of the basin was detected. finally, biannual events in the influx of cold, high salinity, and oxygen rich oceanic water masses into the basin were detected. these events might be related to the same forces driving the coastal upwelling system in the gulf of panama
Size and distribution of Pandarus satyrus (Copepoda: Pandaridae) on the blue shark Prionace glauca (Carcharhiniformes: Carcharhinidae) in Costa Rica
Rojas M.,José Rodrigo; Rodríguez Solano,Omar; Morales-Ramírez,Alvaro;
Revista de Biología Tropical , 2001,
Abstract: a total of 80 specimens of pandarus satyrus, a cosmopolitan ectoparasitic copepod, were taken from fishery catches of blue sharks (prionace glauca) in the eastern pacific coast of costa rica. all specimens were found in the dorsal surface of pectoral fins (8-30 per shark). longer specimens were most abundant.
Size and distribution of Pandarus satyrus (Copepoda: Pandaridae) on the blue shark Prionace glauca (Carcharhiniformes: Carcharhinidae) in Costa Rica
José Rodrigo Rojas M.,Omar Rodríguez Solano,Alvaro Morales-Ramírez
Revista de Biología Tropical , 2001,
Abstract: A total of 80 specimens of Pandarus satyrus, a cosmopolitan ectoparasitic copepod, were taken from fishery catches of blue sharks (Prionace glauca) in the Eastern Pacific coast of Costa Rica. All specimens were found in the dorsal surface of pectoral fins (8-30 per shark). Longer specimens were most abundant. Un total de 80 especímenes de Pandarus satyrus, un copépodo ectoparásito cosmopolita, fueron tomados de tiburones azules (Prionace glauca) capturados en la costa del Pacífico Oriental de Costa Rica. Todos los especímenes fueron encontrados en la superficie dorsal de las aletas pectorales (entre 8 y 30 por tiburón). Los parásitos más grandes son los más abundantes.
Page 1 /44614
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.