Recent Submissions

  • Distribución de quistes de Alexandrium catenella y otros dinoflagelados en sedimentos de la zona sur-austral de Chile

    Lembeye, Georgina (Comité Oceanográfico Nacional, 2004)
    During the expeditions Cimar - Fiordos 2, 3 and 4 (1996, 1997 and 1999), samples of marine sediments were collected in Southern Chile, between Melinka (Lat. 43° 45' S) and Beagle Channel (Lat. 54° 56' S) to study the distribution and abundance of dinoflagellate cysts, particularly the toxic dinoflagellate Alexandriurn catenella. Samples were collected from 33 stations at depths of 1 to 15 meters. The study included photographic record and taxonomic identification of cysts to genus and, whenever possible, to species, with emphasis on the identification of cysts of A. catenella. Cysts from samples collected in cruises 3 and 4, were incubated in f/2-Se culture medium at 13 °C with controlled photoperiod (14:10, L:D), to induce germination and confirm species identification. Through this method, it was possible to establish monoclonal cultures of A. catenella. Cysts of dinoflagellates of at least 18 different forms or species were detected within the samples analyzed. The nine species of dinoflagellates identified belong to 5 genera (Protoperidium, Protoceratium, Scrippsiella, Polykrikos and Alexandrium). The cysts of A. catenella were present in samples of 11 stations. They were most abundant at estero Quitralco (Aysén Region), and at Puerto Engaño (Magallanes Region), with 76,7 ± 23,7 y 72,7 ± 33,8 cysts/mL, respectively. Environmental factors, including oceanographic and geographic conditions, and the characteristics of sediments, may affect the distribution and abundance of the cysts of A. catenella. Those locations may become sources for the generation of toxic blooms in the Aysén and Magallanes Regions.
  • Distribución de clorofila a y feopigmentos en los canales australes chilenos comprendidos entre Puerto Montt y la laguna San Rafael, Chile

    Ramírez, B.; Pizarro, E. (Comité Oceanográfico Nacional, 2005)
    La distribución de clorofila a y su relación con feopigmentos se describe para 98 estaciones localizadas en los fiordos chilenos comprendidos entre 41º a 46º S. Además, es relacionada con la disponibilidad de luz y con la información existente de temperatura, nutrientes, oxígeno y de biomasa planctónica. Las mayores concentraciones de clorofila (>5 mg m–3) se detectaron hasta 25 m, coincidente con una baja concentración de feopigmentos y 50% de luz. Sus más bajas concentraciones (<0,5 mg m–3), fueron detectadas entre 50 y 100 m y asociadas con altos valores de la proporción feopigmento-clorofila. Se establecen cuatro zonas de abundancia de clorofila. La primera tiene concentraciones entre 1,5 y 5 mg m–3, localizadas en seno Reloncaví y golfo de Ancud. La segunda zona tiene baja concentración y se ubica en el golfo Corcovado. La tercera zona corresponde a los canales Moraleda, Jacaf y Puyuguapi. El primero con las máximas concentraciones de toda el área. El canal Jacaf, al oriente del Moraleda también tiene elevadas concentraciones. En cambio, los canales oceánicos (Baeza y King), tienen bajas concentraciones y solo es moderada en el punto de encuentro con el Moraleda. La cuarta zona tiene bajos valores (0,5 a 1,5 mg m–3) y se extiende desde la isla Meninea hasta la laguna San Rafael. El canal Moraleda facilita el crecimiento del fitoplancton porque su cuenca es fertilizada por las aguas oceánicas y la gradiente térmica, detectada en los primeros 25 m, facilita la permanencia de las poblaciones fitoplanctónicas en los niveles fóticos. Las cuencas de seno Reloncaví y golfo de Ancud presentan el mismo patrón de gradiente térmico, pero sus nutrientes son de origen antropogénico.
  • Capacidad de transporte de la constricción de Meninea para un flujo de dos capas y el efecto de la corriente de marea

    Salinas, S.; Hormazábal, S. (Comité Oceanográfico Nacional, 2004)
    En la primavera de 1995, se instaló un anclaje con dos correntómetros sobre el umbral de la constricción de Meninea para un análisis inicial de corrientes. El experimento fue parte del programa multidisciplinario Cimar 1 Fiordos. Durante 61 días se obtuvo las mediciones cada 30 minutos. Los correntómetros estaban instalados a 25 m y 40 m bajo la superficie del mar, en la profundidad de 60 m. La velocidad promedio fue de 15,9 cms-1 hacia el norte en el correntómetro superior y de 2,0 cms-1 hacia el sur en lo profundo. La variabilidad de las corrientes fue dominada por la corriente de marea de tipo semidiurno M2. Debido a la corriente de marea, crece la capacidad de transporte de la constricción con respecto al sistema de dos capas. El tiempo de residencia de las aguas al sur de la constricción es del orden de los 10 meses.
  • Propagación de la onda de marea en canales adyacentes a Campos de Hielo Sur

    Fierro, J.; Castillo, M.; Valenzuela, C. (Comité Oceanográfico Nacional, 2003)
    During the research cruise Cimar-Fiordo 2, carried out in late 1996, sea level was recorded in three stations located in channels, Messier (Puerto Edén), Wide (Punta Beresford) and Concepción (Caleta Patria). The measurements were of short term, starting in October 20th and finishing in December 13th, 1996. The sea level in those stations, was analyzed in the time and frequency dominion, and some tide non harmonic values were calculated. Results showed that tides evident influence in sea level signal, with a clear mixt semidiurnal behavior, and a daily inequality between high and low waters. The highest tide range was observed in puerto Edén, showing the effect of the local orography configuration while the wave propagates into the channel, and experiences non linear effects modification. The low frequency sea level signal is perceptible even it has very small amplitude. However, due to the series short length it was not possible a proper resolution of the low frequency energy spectrum. From the spectral analysis, was clearly advisable that tides is the most energetic phenomenon that shows its biggest expression particularly in the semidiurnal frequency in all stations.
  • Aspectos generales sobre la estructura térmica superficial del mar, de la zona comprendida entre el golfo de Penas y la boca occidental del estrecho de Magallanes

    Boré, D.; Barbieri, M.A.; Catasti, V. (Comité Oceanográfico Nacional, 2001)
    This study was carried out within the Project Cimar-Fiordo 2. The general objective was to describe the sea surface temperature in the zone between 46º LS and 52º LS, and from the 73º 52’ LW to the 76º 30’ LW, considering the channel and fjord zone. The analysis was based on satellite images of sea surface temperature. The images used came from the AVHRR radiometer of the NOAA satellite, from the year 1995 to 1998. The cartographic representation and the analysis of the seasonal variability of the sea surface temperature was made using the software of the Geographical Information System (GIS), named IDRISI. The zone was with clouds during all the period of study, mainly in autumn. With the available images it was possible to observe a big difference between the summer and winter temperatures. Equally, in all the seasons, the sea surface temperature diminished from the north to the south zone.
  • Caracterización del régimen de mareas y corrientes a lo largo del canal Moraleda (43° 54' S - 45° 17' S)

    Fierro, J.; Bravo, M.; Castillo, M. (Comité Oceanográfico Nacional, 2000)
    Sea level and currents in “Boca del Guafo” and Moraleda channel are studied using statististical and Fourier (harmonic) analyses. The data were collected using oceanographic instruments that covered a wide geographical area, from the northern most point of Moraleda channel to Darwin channel. The results of the harmonic analysis indicated that the area has a semidiurnal tide with a 12-minute phase shift between the ports of Melinka and Lagunas. This result shows that the tidal wave does not only propagate along the Moraleda channel, but at the same time enters the region through several transversal channels that connect the Pacific Ocean with the Moraleda channel. Along the main channel (Moraleda) no reverse current was recorded, which is an unusual characteristic for the channels and inlets in the Chilean Inland Seas. The main reason for this unexpected behavior is due to the fact that currents are also forced by long period disturbances that could be related to meteorological processes. The maximum currents recorded were 66.5 cm/s and 53.7 cm/s at stations SHOA-2 and SHOA-1, respectively.
  • Distribución espacial del amonio en fiordos y canales comprendidos entre Puerto Montt y Laguna San Rafael en período de primavera

    Prado-Fiedler, R. (Comité Oceanográfico Nacional, 2000)
    An oceanographic expedition was carried out between October 18th and November 15th 1995 in the inlets region and fjords located between Puerto Montt (41° 20’S and San Rafael Lagoon (46° 40’ S) in Southern Chile. The main purpose of the present work is to characterise the spatial distribution of ammonium and its concentration range in the studied region during spring onset. Water samples were collected from a total of 101 oceanographic stations of the expedition Cimar-Fiordo 1. The main part of the water body showed concentrations lower than 1 µmol/L. The higher ammonium concentrations were found in the continental fjords, specially in the area situated south of the narrows of Meninea island, where subsurface maximums greater than 2 µmol/L were found. The vertical distribution of ammonium concentration presents a three layer structure for the whole area. The surface layer was 20 m thick and had concentrations lower than 0.5 µmol/L. This layer was followed in depth by one having a subsurface maximum of ammonium. Finally, a third deep and thicker layer with very low concentrations, even under the limit of detection was found. The continental fjords showed concentrations significantly higher than those of the inlet channels located westward of the main axis formed by the Corcovado gulf, Moraleda, Costa and Elefantes channels. This was particularly the case of the most superficial layer (less than 5 m depth). This difference is attributed to the organic nitrogen supply of land vegetal origin.