CEAZA
Evaluation of sediment trace metal records as paleoproductivity and paleoxygenation proxies in the upwelling center off Concepción, Chile (36°S)
Muñoz, P., Dezileau, L., Lange, C., Cardenas, L., Sellanes, J., Salamanca, M., & Maldonado, A.
This study analyzes the records of several trace metals sensitive to redox conditions in continental shelf sediments off Concepción, Chile (36°S). The continental margin off Concepción (36°S; 73°W) lies beneath an important upwelling center characterized by high primary production rates and, consequently, high fluxes of organic matter. In spring and summer, this material settles to the seafloor where it decays, producing periods of very low oxygen content in bottom waters (<1 mL L−1). In addition, an oxygen minimum zone develops at ∼100–400 m water depth, where dissolved oxygen levels are <0.5 mL L−1. This situation changes during strong El Niño events, when dissolved oxygen at the bottom increases drastically (>1 mL L−1).
Año: 2012
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Referencia APA: Muñoz, P., Dezileau, L., Lange, C., Cardenas, L., Sellanes, J., Salamanca, M., & Maldonado, A. (2012). Evaluation of sediment trace metal records as paleoproductivity and paleoxygenation proxies in the upwelling center off Concepción, Chile (36°S). Progress In Oceanography, 92-95, 66-80.
A three-year mark-recapture study in a remnant population of Crocodylus acutus Cuvier in Portete Bay (Guajira, Colombia).
Espinosa, M., Bertin, A., Gómez, J., Mejía, F., Guerra, M., & Baez, L., Gouin, N., Patiño, E.
El Cocodrilo Americano Crocodylus acutus, ha experimentado importantes declines poblacionales a lo amplio de su distribución debido a la persecución humana, la sobreexplotación y la pérdida de hábitat. C. acutus permanece en peligro crítico en algunos países tales como Colombia donde la ausencia de estudios detallados sobre su ecología y distribución constituyen una de las barreras principales para el desarrollo de efectivas estrategias de conservación. Durante tres años desarrollamos un estudio de captura-recaptura para investigar el estatus demográfico de C. acutus e identificar las variables medioambientales más influyentes en su distribución en Bahía Portete (Colombia). Nosotros estimamos que la población de cocodrilos es relativamente pequeña (< 140 animales), incluye muy pocos adultos y demuestra un fuerte déficit de hembras en la clase juvenil. La humedad relativa y la temperatura promedio del aire estuvieron positivamente correlacionadas con el número de avistamientos de cocodrilos. Por el contrario, la salinidad promedio del agua se encontró relacionada con la baja probabilidad de observación, presumiblemente debido a la preferencia de los juveniles por áreas de baja salinidad. Nuestros resultados sugieren que la población de C. acutus en Bahía Portete está en riesgo y puede requerir la intervención humana para asegurar su persistencia.
Año: 2012
Palabras claves: Captura-recaptura, cocodrilo, variables medioambientales, manglar
Referencia APA: Espinosa, M., Bertin, A., Gómez, J., Mejía, F., Guerra, M., & Baez, L., Gouin, N., Patiño, E. (2012). A three-year mark-recapture study in a remnant population of Crocodylus acutus Cuvier in Portete Bay (Guajira, Colombia). Gayana (Concepción), 76(1), 52-58.
Annual brood number and breeding periodicity of squat lobsters (Decapoda: Anomura: Galatheidae) from the continental shelf of the SE Pacific—Implications for fisheries management.
Thiel, M., Espinoza-Fuenzalida, N., Acuña, E., & Rivadeneira, M.
The reproductive potential of a population depends on the number of broods that individuals produce during the annual reproductive season. Determining the annual brood number is especially relevant for species that are actively fished. Herein we combined different approaches to estimate the annual brood number of two commercially exploited species of squat lobsters from the Chilean continental shelf and upper slope, Cervimunida johni and Pleuroncodes monodon. Long-term maintenance in the laboratory revealed that most females (>70%) produced 3 or more broods during the annual reproductive season. Incubation of individual broods required about 40 days, which would allow for 3 subsequent broods during the main reproductive period (June–September). The dynamics of brood release of ovigerous females that were collected from the field at approximately monthly intervals supported the estimate of 3–4 annual broods for adult females. Furthermore, these latter data also indicated a high degree of breeding synchrony among reproductive females. It is suggested that the production of successive broods might be an adaption to the variable oceanographic conditions during the reproductive period, ensuring that at least one larval cohort finds favorable conditions for development and settlement. Based on these results it is recommended that fishing effort is reduced during the main reproductive period of the two squat lobsters.
Año: 2012
Palabras claves: Squat lobsters; Trawl fishery; Fisheries management; Reproduction; Annual brood number; Mating synchrony
Referencia APA: Thiel, M., Espinoza-Fuenzalida, N., Acuña, E., & Rivadeneira, M. (2012). Annual brood number and breeding periodicity of squat lobsters (Decapoda: Anomura: Galatheidae) from the continental shelf of the SE Pacific—Implications for fisheries management. Fisheries Research, 129-130, 28-37.
Major hydrological regime change along the semiarid western coast of South America during the early Holocene.
Ortega, C., Vargas, G., Rutllant, J., Jackson, D., & Méndez, C.
Water availability in the semiarid western coast of Chile (30–32°S) is conditioned by high interannual precipitation variability, reflecting the transition between arid subtropical and moist mid-latitude climates in the Southeastern Pacific Ocean. A paleoclimate reconstruction based on the latest Pleistocene–Holocene geological record from the Quebrada Santa Julia archeological site in Chile (31°50′S) and on modern meteorological mechanisms producing alluvial episodes in this region indicates a major change in the rainfall regime shortly after 8600 cal yr BP. This, together with other paleoclimate proxies along the west coast of South America (34°–14°S), suggests La Niña-like conditions 13,000–8600 cal yr BP. Based on sedimentological and geomorphologic evidence, we hypothesized that the absence of heavy rainfall events in northern Chile and the new hydrological regime that prevailed ca. 8600–5700 cal yr BP in north-central Chile resulted from an increase in the large-scale westerly flow over central Chile, as expected in near-neutral ENSO conditions. This atmospheric circulation anomaly is compatible with an equatorward shift of the influence of the Southeast Pacific Subtropical Anticyclone relative to the early Holocene, prior to the onset of modern ENSO variability.
Año: 2012
Palabras claves: Paleoclimate; Early Holocene; Alluvial flow; Heavy rainfall; Coastal fog; El Niño Southern Oscillation (ENSO); Western South America; Paleohydrology; Pacific Ocean.
Referencia APA: Ortega, C., Vargas, G., Rutllant, J., Jackson, D., & Méndez, C. (2012). Major hydrological regime change along the semiarid western coast of South America during the early Holocene. Quaternary Research, 78(3), 513-527.
What do we know about high-altitude precipitation in the semi-arid Andes of Chile?
Bourgin P, Andreassian V, Gascoin S, Valery A.
Mapping precipitations on a regular grid is often required for hydrological and ecological modelling. The spatial interpolation methods are generally used to estimate such a distribution from ground-based measurements. In the case of mountainous areas, the estimation of precipitation amounts is still a challenging task and the results of spatial interpolation should be verified as much as possible. Here we describe a three-steps method for the validation of a precipitation map. This is used in the context of a mountainous semi-arid region, the Norte Chico in Chile (26°S-32°S). The implementation of this validation method showed the benefits of an interpolation method developed by Valéry [2010] for mountainous areas. The hydrological balance of the high-altitude watersheds is now more realistic.
Año: 2012
Palabras claves: Precipitation, spatial interpolation method, extrapolation, altitude, altitudinal corrections, validation, water equivalent, water balance.
Referencia APA: Bourgin P, Andreassian V, Gascoin S, Valery A. (2012). Que sait-on des précipitations en altitude dans les Andes semi-arides du Chili?. La Houille Blanche. 2012;(2):12-17.