Search

espanolSe analizo la relacion entre el bacterioplancton y las condiciones oceanograficas en un area de surgencia en el norte de Chile, mediante aproximacion basada en las abundancias y tamanos celulares. El area de estudio fue bahia Chipana (21°20'S), se analizaron los veranos del 2004-2006 y los inviernos 2005-2007. La temperatura, salinidad y oxigeno se registraron mediante un CTD, las muestras de bacterioplancton y clorofila-a fueron obtenidas a profundidades estandares. La variabilidad de la estructura fisica de la columna de agua se asocio a eventos de surgencia, bajo la influencia de la zona de minimos de oxigeno y eventos El Nino-La Nina. La mayor abundancia del bacterioplancton se observo en diciembre 2004 y julio 2005, asociadas al margen costero (1,07×10(9)-5,12×10(9) cel L-1 y 1,44×10(9) cel L-1, respectivamente). Para el 2006 y 2007, se detecto una menor abundancia en el margen costero y en la capa superficial de las estaciones mas alejadas de la costa, los valores fluctuaron entre 6,77×10(7)-3,67×10(9) cel L-1, respectivamente. El uso de modelos aditivos generalizados, permitio determinar que la salinidad, estabilidad de la columna de agua y biomasa del fitoplancton tuvieron un efecto significativo sobre la abundancia procariota. Los mayores volumenes celulares se asociaron a las menores abundancias, siendo la estructura de tamano dominante 0,4-0,8 y 0,8-1,2 µm de longitud. Este estudio sugiere que la abundancia y el tamano celular del bacterioplancton sufren variaciones temporales que se relacionan a factores fisicos, principalmente la salinidad y estabilidad de la columna de agua. La transicion observada entre eventos El Nino-La Nina genera cambios en la columna de agua asociados a una profundizacion de la termoclina, que expande y contrae la OMZ, que finalmente podrian afectar la capacidad productiva del bacterioplancton. EnglishThe relationship between bacterioplankton and oceanographic conditions of an upwelling area of northern Chile was analyzed, during two contrasting seasons, emphasizing an approach based in the abundance and size structure. The study area was Chipana Bay (21°20'S), and analyzed the summers of 2004-2006 and winters of 2005-2007. The temperature, salinity and oxygen were recorded with a CTD and the bacterioplankton and chlorophyll-a samples were obtained at standards depths. The variability of the physical structure of the water column was associated with upwelling, under the influence of the oxygen minimum zone and El Nino-La Nina events. The higher abundance of bacterioplankton was observed in December 2004 and July 2005, (1.07×10(9)-5.12×10(9) cell L-1 and 1.44×10(9) cell L-1, respectively), associated with coastal margin and surface water away from the coast. For 2006 and 2007, a lower abundance was detected in the coastal margin and in the surface layer of the offshore stations, the values fluctuated between 6.77 × 10(7)-3.67 × 10(9) cells L-1, respectively. The use of generalized additive models determined that the best predictors were salinity, dissolved oxygen and the total chlorophyll. The higher cell volumes associated with low abundance, being the dominant structure size 0.4-0.8 and 0.8-1.2 µm in length. This study suggests that the abundance and cellular size of bacterioplankton undergo temporal variations that are related to physical factors, mainly salinity and stability of the water column. The observed transition between El Nino and La Nina causes changes in the water column associated with a deepening of the thermocline, which expands and contracts the OMZ, which could eventually affect the productive capacity of the bacterioplankton.

Observations on Chelonia mydas agassizii have been carried out on a monthly basis for the last 2 years along the Chinchorro beach in Arica (northern Chile), with the aim of monitoring and describing genetic and population parameters in this group of turtles. Eighteen Ch. mydas agassizii individuals were captured and marked from December 2011, to July 2013. These individuals had long carapace of 47 to 75.7 cm, of which 11 were identified as females and the rest were of undetermined sex (individuals of smaller sizes). We were only able to recapture one of such individuals 6 months later in the same feeding area. Sequencing of the mtDNA Control Region showed 4 haplotypes: 3 that had never been described before and one observed in several regions of the Pacific (Japan, Mexico and Ecuador). This information suggests that Ch. mydas agassizii may stay in the same feeding zone for months. Nevertheless, the genetic information did not indicate any association between the individuals captured from the Chinchorro Beach and a nesting area in the Pacific.