Narváez Diego

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Last Name
Narváez
First Name
Diego
ORCID
0000-0001-9866-1189

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  • Article
    Isotopic characterization of water masses in the Southeast Pacific Region: paleoceanographic implications
    (American Geophysical Union, 2021-12-23) Reyes-Macaya, Dharma ; Hoogakker, Babette ; Martínez-Méndez, Gema ; Llanillo, Pedro J. ; Grasse, Patricia ; Mohtadi, Mahyar ; Mix, Alan C. ; Leng, Melanie J. ; Struck, Ulrich ; McCorkle, Daniel C. ; Troncoso, Macarena ; Gayo, Eugenia M. ; Lange, Carina B. ; Farias, Laura ; Carhuapoma, Wilson ; Graco, Michelle ; Cornejo-D’Ottone, Marcela ; De Pol-Holz, Ricardo ; Fernandez, Camila ; Narváez, Diego ; Vargas, Cristian A. ; García-Araya, Francisco ; Hebbeln, Dierk
    In this study, we used stable isotopes of oxygen (δ18O), deuterium (δD), and dissolved inorganic carbon (δ13CDIC) in combination with temperature, salinity, oxygen, and nutrient concentrations to characterize the coastal (71°–78°W) and an oceanic (82°–98°W) water masses (SAAW—Subantarctic Surface Water; STW—Subtropical Water; ESSW—Equatorial Subsurface water; AAIW—Antarctic Intermediate Water; PDW—Pacific Deep Water) of the Southeast Pacific (SEP). The results show that δ18O and δD can be used to differentiate between SAAW-STW, SAAW-ESSW, and ESSW-AAIW. δ13CDIC signatures can be used to differentiate between STW-ESSW (oceanic section), SAAW-ESSW, ESSW-AAIW, and AAIW-PDW. Compared with the oceanic section, our new coastal section highlights differences in both the chemistry and geometry of water masses above 1,000 m. Previous paleoceanographic studies using marine sediments from the SEP continental margin used the present-day hydrological oceanic transect to compare against, as the coastal section was not sufficiently characterized. We suggest that our new results of the coastal section should be used for past characterizations of the SEP water masses that are usually based on continental margin sediment samples.
  • Article
    Intraseasonal variation in southeast Pacific blue whale acoustic presence, zooplankton backscatter, and oceanographic variables on a feeding ground in Northern Chilean Patagonia
    (Elsevier, 2021-11-09) Buchan, Susannah J. ; Pérez-Santos, Iván ; Narváez, Diego ; Castro, Leonardo ; Stafford, Kathleen M. ; Baumgartner, Mark F. ; Valle-Levinson, Arnoldo ; Montero, Paulina ; Gutierrez, Laura ; Rojas, Constanza ; Daneri, Giovanni ; Neira, Sergio
    Seasonal variation in the acoustic presence of blue whale calls has been widely reported for feeding grounds worldwide, however variation over the submonthly scale (several days to <1 month) has been examined to a much lesser extent. This study combines passive acoustic, hydroacoustic, and in situ oceanographic observations collected at a mooring in the Corcovado Gulf, Northern Chilean Patagonia, from January 2016-February 2017, to examine the temporal variation in blue whale acoustic occurrence and prey backscatter over seasonal and submonthly scales. Time series data for a) Southeast Pacific blue whale song calls and D-calls, b) zooplankton backscatter, c) tidal amplitude, and d) meridional and zonal wind stress were examined visually for seasonal trends. To examine submonthly timescales over the summer feeding season (January-June), wavelet transforms and wavelet coherence were applied; generalized linear models (GLM) were also applied. There was a 3-month lag between the seasonal onsets of high zooplankton backscatter (October) and blue whale acoustic presence (January), and an almost immediate drop in blue whale acoustic presence with the seasonal decrease of backscatter (June). This may be due to the use of memory by animals when timing their arrival on the feeding ground, but the timing of their departure may be related to detection of low prey availability. Over the summer feeding season, blue whale acoustic presence was strongly associated with zooplankton backscatter (GLM coefficient p ≪ 0.0001). Song calls followed a seasonal cycle, but D-calls appeared to respond to short term variations in environmental conditions over submonthly scales. Results suggest that spring tides may increase prey aggregation and/or transport into the Corcovado Gulf, leading to increased blue whale acoustic presence over 15-day or 30-day cycles; and short-lived events of increased wind stress with periodicities of 2–8 days and 16–30 days, may also contribute to the aggregation of prey. We discuss the strengths and limitations of coupling passive and active acoustic data to examine drivers of blue whale distribution.