Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collect... more Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collection of surface salinity data were made to study the transverse variability of residual flows and salinity in Paso Nao (Lat. 41.9o S), one of the main ways for exchanging of waters between Seno Reloncavi and Golfo de Ancud. 14 repetitions were made in 24 hours on November 13, 2004, over a quasirectangular circuit in Paso Nao, where two of its transects were oriented in the east-west direction. Residual velocities and salinity distributions showed differences between the two east-west transects, which was mostly attributed to the effect of bathymetry. Northern transect showed a vertical distribution of residual flows in three layers, where the first layer of outflow (southward) in the first 20 m depth, was attributed to the effect of freshwater discharge to the system. The second layer (northward) was attributed to the effect of tidal wave and a third layer below 60 m, confined to the deep...
ABSTRACT The influence of oceanographic features and moon phases on ichthyoplankton assemblages i... more ABSTRACT The influence of oceanographic features and moon phases on ichthyoplankton assemblages in a temperate nearshore rocky reef off El Quisco Bay, central Chile, was assessed during austral spring–summer 2015–2016 using Bongo nets. Wind direction was predominantly south-west, and ocean temperature increased gradually during the study period, fluctuating between 11.6°C and 17.7°C. A relatively cold period (from late September to early December, 12.42 ± 0.64°C) was distinguished from a relatively warmer phase (from mid-December to February, 13.56 ± 1.08°C). Nearshore ichthyoplankton was composed of 13,700 individuals, belonging to 43 taxa. Larval Strangomera bentincki (Clupeidae) were collected in high numbers between late September and late October with peaks during full moon and first quarter (maximum = 734 ind. 100 m−3); larval Engraulis ringens (Engraulidae) was most abundant between late October and late December 2015, with peaks during the third quarter and full moon. Principal Component Analysis of ichthyoplankton data explained more than 44% of total variance and showed the influence of cold/warm periods in the structuring of larval fish assemblages. Water temperature had more influence than lunar phase in the structure and composition of nearshore fish larvae off central Chile. We conclude that larval fish assemblages found in nearshore waters change on a seasonal scale by differences in the reproductive activity among species, and that lunar phase exerts a low, but significant effect on the abundance of fish larvae, but this variability is species-specific.
Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collect... more Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collection of surface salinity data were made to study the transverse variability of residual flows and salinity in Paso Nao (Lat. 41.9º S), one of the main ways for exchanging of waters between Seno Reloncavi and Golfo de Ancud. 14 repetitions were made in 24 hours on November 13, 2004, over a quasi- rectangular circuit in Paso Nao, where two of its transects were oriented in the east-west direction. Residual velocities and salinity distributions showed differences between the two east-west transects, which was mostly attributed to the effect of bathymetry. Northern transect showed a vertical distribution of residual flows in three layers, where the first layer of outflow (southward) in the first 20 m depth, was attributed to the effect of freshwater discharge to the system. The second layer (northward) was attributed to the effect of tidal wave and a third layer below 60 m, confined to the de...
We describe a seiche process in a Chilean fjord, based on current, temperature and sealevel data ... more We describe a seiche process in a Chilean fjord, based on current, temperature and sealevel data obtained from the Reloncavi fjord (41.6° S, 72.5° W) in southern Chile. We combined four months of ADCP data with sealevel, temperature and wind time series to analyze the dynamics of low-frequency (periods > 1 day) internal oscillations in the fjord. Additionally, seasonal CTD data from 19 along-fjord stations were used to characterize the seasonality of the density field. The density profiles were used to estimate the internal long-wave phase speed (c) using two approximations: (1) a simple reduced gravity model (RGM) and (2) a continuously stratified model (CSM). No major seasonal changes in c were observed using either approximation (e.g., the CSM yielded 0.73 < c < 0.87 m s−1 for mode 1). The natural internal periods (TN) were estimated using Merians’s formula for a simple fjord-like basin and the above phase speeds. Estimated values of TN varied between 2.9 and 3.5 d...
... The results show the main features of the circulation at the mouth of this fjord and other ph... more ... The results show the main features of the circulation at the mouth of this fjord and other phenomena of interest for physical ... Navigation data was obtained with a GPS (Global Positioning System) ASHTEC Z-12 interfaced to a laptop computer in combination with the ADCP ...
Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collect... more Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collection of surface salinity data were made to study the transverse variability of residual flows and salinity in Paso Nao (Lat. 41.9o S), one of the main ways for exchanging of waters between Seno Reloncavi and Golfo de Ancud. 14 repetitions were made in 24 hours on November 13, 2004, over a quasirectangular circuit in Paso Nao, where two of its transects were oriented in the east-west direction. Residual velocities and salinity distributions showed differences between the two east-west transects, which was mostly attributed to the effect of bathymetry. Northern transect showed a vertical distribution of residual flows in three layers, where the first layer of outflow (southward) in the first 20 m depth, was attributed to the effect of freshwater discharge to the system. The second layer (northward) was attributed to the effect of tidal wave and a third layer below 60 m, confined to the deep...
ABSTRACT The influence of oceanographic features and moon phases on ichthyoplankton assemblages i... more ABSTRACT The influence of oceanographic features and moon phases on ichthyoplankton assemblages in a temperate nearshore rocky reef off El Quisco Bay, central Chile, was assessed during austral spring–summer 2015–2016 using Bongo nets. Wind direction was predominantly south-west, and ocean temperature increased gradually during the study period, fluctuating between 11.6°C and 17.7°C. A relatively cold period (from late September to early December, 12.42 ± 0.64°C) was distinguished from a relatively warmer phase (from mid-December to February, 13.56 ± 1.08°C). Nearshore ichthyoplankton was composed of 13,700 individuals, belonging to 43 taxa. Larval Strangomera bentincki (Clupeidae) were collected in high numbers between late September and late October with peaks during full moon and first quarter (maximum = 734 ind. 100 m−3); larval Engraulis ringens (Engraulidae) was most abundant between late October and late December 2015, with peaks during the third quarter and full moon. Principal Component Analysis of ichthyoplankton data explained more than 44% of total variance and showed the influence of cold/warm periods in the structuring of larval fish assemblages. Water temperature had more influence than lunar phase in the structure and composition of nearshore fish larvae off central Chile. We conclude that larval fish assemblages found in nearshore waters change on a seasonal scale by differences in the reproductive activity among species, and that lunar phase exerts a low, but significant effect on the abundance of fish larvae, but this variability is species-specific.
Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collect... more Measurements of currents using a towed ADCP (Acoustic Doppler Current Profiler (ADCP) and collection of surface salinity data were made to study the transverse variability of residual flows and salinity in Paso Nao (Lat. 41.9º S), one of the main ways for exchanging of waters between Seno Reloncavi and Golfo de Ancud. 14 repetitions were made in 24 hours on November 13, 2004, over a quasi- rectangular circuit in Paso Nao, where two of its transects were oriented in the east-west direction. Residual velocities and salinity distributions showed differences between the two east-west transects, which was mostly attributed to the effect of bathymetry. Northern transect showed a vertical distribution of residual flows in three layers, where the first layer of outflow (southward) in the first 20 m depth, was attributed to the effect of freshwater discharge to the system. The second layer (northward) was attributed to the effect of tidal wave and a third layer below 60 m, confined to the de...
We describe a seiche process in a Chilean fjord, based on current, temperature and sealevel data ... more We describe a seiche process in a Chilean fjord, based on current, temperature and sealevel data obtained from the Reloncavi fjord (41.6° S, 72.5° W) in southern Chile. We combined four months of ADCP data with sealevel, temperature and wind time series to analyze the dynamics of low-frequency (periods > 1 day) internal oscillations in the fjord. Additionally, seasonal CTD data from 19 along-fjord stations were used to characterize the seasonality of the density field. The density profiles were used to estimate the internal long-wave phase speed (c) using two approximations: (1) a simple reduced gravity model (RGM) and (2) a continuously stratified model (CSM). No major seasonal changes in c were observed using either approximation (e.g., the CSM yielded 0.73 < c < 0.87 m s−1 for mode 1). The natural internal periods (TN) were estimated using Merians’s formula for a simple fjord-like basin and the above phase speeds. Estimated values of TN varied between 2.9 and 3.5 d...
... The results show the main features of the circulation at the mouth of this fjord and other ph... more ... The results show the main features of the circulation at the mouth of this fjord and other phenomena of interest for physical ... Navigation data was obtained with a GPS (Global Positioning System) ASHTEC Z-12 interfaced to a laptop computer in combination with the ADCP ...
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