Articles | Volume 12, issue 2
Ocean Sci., 12, 533–544, 2016
Ocean Sci., 12, 533–544, 2016

Research article 12 Apr 2016

Research article | 12 Apr 2016

Seasonal hydrography and surface outflow in a fjord with a deep sill: the Reloncaví fjord, Chile

Manuel I. Castillo1,2, Ursula Cifuentes2,6, Oscar Pizarro2,3,4, Leif Djurfeldt5, and Mario Caceres1 Manuel I. Castillo et al.
  • 1Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Viña del Mar, Chile
  • 2Center for Oceanographic Research in the Eastern South Pacific (COPAS)-Sur Austral, Universidad de Concepción, Concepción, Chile
  • 3Departamento de Geofísica, Universidad de Concepción, Concepción, Chile
  • 4Instituto Milenio de Oceanografía, Universidad de Concepción, Concepción, Chile
  • 5Department of Oceanography, Earth Sciences Center, Gothenburg University, Gothenburg, Sweden
  • 6Departamento de Oceanografía y Medio Ambiente, Instituto de Fomento Pesquero, Valparaíso, Chile

Abstract. Seasonal data on temperature, salinity, dissolved oxygen (DO) and chlorophyll, combined with meteorological and river discharge time series, were used to describe the oceanographic conditions of the Reloncaví fjord (41°35′ S, 72°20′ W). The winds in the fjord valley mainly blow down-fjord during the winter, reinforcing the upper layer outflow, whereas the winds blow predominantly up-fjord during the spring and summer, contrary to the upper layer outflow. The fjord, with a deep sill at the mouth, was well stratified year-round and featured a thin surface layer of brackish water with mean salinities between 10.4 ± 1.4 (spring) and 13.2 ± 2.5 (autumn). The depth of the upper layer changed slightly among the different studied seasons but remained at 4.5 m near the mouth. This upper layer presented a mean outflow (Q1) of 3185 ± 223 m3 s−1, which implies a flushing time of 3 days for this layer. The vertical salt flux was  ∼  37 tons of salt per second, similar to the horizontal salt flux observed in the upper layer. These estimates will contribute to better management of the aquaculture in this region.

Short summary
The upper layer of the Reloncaví fjord, Chile, shows a continuous stratification year-round. Nevertheless, the vertical salt flux seems to be balanced by the horizontal salt flux, which maintains the amount of salt into the fjord nearly as a steady state. The upper layer shows a flushing time of about 3 days.