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Páramos, tropical alpine ecosystems, host one of the world s most diverse alpine floras, account for the largest water reservoirs in the Andes, and some of the largest soil carbon pools worldwide. It is of global importance to understand the future of this extremely carbon-rich ecosystem in a warmer world and its role on global climate feedbacks. This study presents the result of the first in situ warming experiment in two Colombian páramos using Open-Top Chambers. We evaluated the response to warming of several ecosystem carbon balance-related processes, including decomposition, soil respiration, photosynthesis, plant productivity, and vegetation structure after 3 years of warming. We found that OTCs are an efficient warming method in the páramo, increasing mean air temperature by 1.7°C and mean daytime temperature by 3.4°C. The maximum air temperature differences between OTC and control was 23.1°C. Soil temperature increased only by 0.1°C. After 3 years of warming using 20 OTC (10 per páramo) in a randomized block design, we found no evidence that warming increased CO2 emissions from soil respiration, nor did it increase decomposition rate, photosynthesis or productivity in the two páramos studied. However, total C and N in the soil and vegetation structure are slowly changing as result of warming and changes are site dependent. In Sumapaz, shrubs, and graminoids cover increased in response to warming while in Matarredonda we observed an increase in lichen cover. Whether this change in vegetation might influence the carbon sequestration potential of the páramo needs to be further evaluated. Our results suggest that páramos ecosystems can resist an increase in temperature with no significant alteration of ecosystem carbon balance related processes in the short term. However, the long-term effect of warming could depend on the vegetation changes and how these changes alter the microbial soil composition and soil processes. The differential response among páramos sug

Electrostatic field measurements taken in Bogotá, Colombia, during thunderstorms in November (the rainy season due to inter-tropical confluence zone over central Colombia) were used to study the performance of an isolated electric field sensor and analyse its most important operational characteristics. The distances from each flash to the studied sensor were obtained by using the Colombian lightning location system. The ΔE cf distance ratio led to defining a charge model which could be used as a reference for calibrating other electrostatic field sensors to be used as lightning warning systems., Medidas de campo electrostático realizadas en Bogotá durante episodios de tormenta en noviembre de 2010 (típicamente temporada de lluvias dada por el paso de la zona de confluencia intertropical por el centro de Colombia) fueron usadas para estudiar y analizar las características operacionales más importantes de un sensor de campo electrostático aislado. Las distancias de cada descarga nube-tierra con respecto al sensor obtuvieron a partir de los datos suministrados por el SID (Sistema de Información de Descargas). Los ΔE en función de la distancia permitieron definir un modelo de carga puede ser utilizado como sistema de referencia para la calibración de otros sensores de campo electrostático a ser implementados en sistemas de alerta de tormentas eléctricas.

The effect of a delivery system (implant) loaded with gonadotropin-releasing hormone agonist (GnRHa) on the spawning performance in captive-reared Atlantic bluefin tuna (Thunnus thynnus) was assessed by means of stereological quantification of ovarian post-ovulatory follicles (POF). Among untreated control fish no follicles were observed at the oocyte maturation (OM) stage; in contrast, 10 of the 16 GnRHa-treated fish showed follicles containing migratory-nucleus oocytes and/or hydrating oocytes. Post-ovulatory follicles were observed only in three of the 14 untreated individuals examined, while all but one GnRHa-induced fish showed POF in the ovary. Nevertheless, when POF were present in the ovary, the amount of ovulated oocytes was not found to be significantly different among GnRHa-treated and untreated control fish, and wild spawners. The relative batch fecundity (eggs g− 1 of body mass) estimated from ovarian POF counts were 109.62 ± 28.36 (control group), 68.92 ± 13.05 (GnRHa-treated group) and 83.47 ± 15.63 (wild group). It was concluded that treatment with GnRHa implant stimulated OM and spawning in captivity, thus enhancing the reproductive potential of the broodstocks; however, there appears to be a limitation in the number of eggs maturing in each batch, and the spawn fecundity was not increased by the hormonal treatment.