R. Escribano

University of Concepción, Ciudad de Concepcion, Biobío, Chile

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Publications (169)283.25 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A 10-year time series (2002-2012) at Station 18 off central/southern Chile allowed us to study variations in zooplankton along with interannual variability and trends in oceanographic conditions. We used an automated analysis program (ZooImage) to assess changes in the mesozooplankton size structure and the composition of the taxa throughout the entire community. Oceanographic conditions changed over the decade: the water column became less stratified, more saline, and colder; the mixed layer deepened; and the oxygen minimum zone became shallower during the second half of the time series (2008-2012) in comparison with the first period (2002-2007). Both the size structure and composition of the zooplankton were significantly associated with oceanographic changes. Taxonomic and size diversity of the zooplankton community increased to the more recent period. For the second period, small sized copepods (<1 mm) decreased in abundance, being replaced by larger sized (>1.5 mm) and medium size copepods (1-1.5 mm), whereas euphausiids, decapod larvae, appendicularian and ostracods increased their abundance during the second period. These findings indicated that the zooplankton community structure in this eastern boundary ecosystem was strongly influenced by variability of the upwelling process. Thus, climate-induced forcing of upwelling trends can alter the zooplankton community in this highly productive region with potential consequences for the ecosystem food web.
    No preview · Article · Jan 2016 · Progress In Oceanography
  • Carolina E. González · Ruben Escribano · Pamela Hidalgo
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    ABSTRACT: Copepods are major components of zooplankton in the Humboldt Current system. Here, intra-seasonal (monthly) variation of upwelling and its influence on the copepod community were assessed. Species abundances, species richness, diversity (Shannon–Wiener index) and dominance, were studied during four upwelling periods (2002–2009) at the Station 18 time series off of Concepción (36°S). Although 77 species were identified, most variability of the community structure was explained by few (<10) species. A negative trend in copepod abundance over the years was associated with lower oxygenation of the mixed layer. A generalized linear model test for relationships among community descriptors and environmental parameters (temperature, dissolved oxygen, chlorophyll, and water column stratification) revealed that diversity was positively correlated with stratification. Upwelling variation, reflected in alternate periods (active and relaxed), characterized two distinct communities during the spring–summer. The study concludes that upwelling interacts with copepod populations by changing stratification, and temperature and oxygenation gradients. The study also suggests that greatly increased upwelling may negatively impact copepods by reducing oxygenation, cooling down the mixed layer and causing more advection. The same mechanisms may be operating in other systems, and thus this study provides clues on how zooplankton communities can respond to climate-induced variation of upwelling.
    No preview · Article · Oct 2015 · Hydrobiologia
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    ABSTRACT: Recent field and experimental evidence collected in the southern upwelling region off Concepción (36°5’S, 73°3’W) showed an abrupt reduction (<72 h) in the egg production rates (EPR) of copepods when they were fed steadily and solely with the local bloom-forming diatom Thalassiosira rotula. Because diatoms were biochemically similar to dinoflagellate Prorocentrum minimum, a diet which supported higher reproductive outcomes, the fecundity reduction observed in copepod females fed with the diatom may have obeyed to post-ingestive processes, giving rise to resources reallocation. This hypothesis was tested by comparing feeding (clearance and ingestion rates), reproduction (EPR and hatching success) and the structure of protein profiles (i.e., number and intensity of electrophoretic bands) of copepods (adults and eggs) incubated during 96 h with the two food conditions. The structure of protein profiles included molecular sizes that were calculated from the relative mobility of protein standards against the logarithm of their molecular sizes. After assessing the experimental conditions, feeding decreased over time for those females fed with T. rotula, while reproduction was higher in females fed with P. minimum. Electrophoretic profiles resulted similar mostly at a banding region of 100 to 89-kDa, while they showed partial differences around the region of 56-kDa band, especially in those females fed and eggs produced with T. rotula. Due to reproductive volume was impacted while larvae viability, a physiological processes with specific and high nutritional requirements, was independent on food type; post-ingestive processes, such as expression of stress-related proteins deviating resources to metabolic processes others than reproduction, are discussed under framework of nutritional-toxic mechanisms mediating copepod-diatoms relationships in productive upwelling areas.
    No preview · Article · Sep 2015 · Latin American Journal of Aquatic Research
  • B. Maté · I. Tanarro · R. Escribano · M. A. Moreno · V. J. Herrero
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    ABSTRACT: The destruction of solid glycine under irradiation with 2 keV electrons has been investigated by means of IR spectroscopy. Destruction cross sections, radiolysis yields, and half-life doses were determined for samples at 20, 40, 90, and 300 K. The thickness of the irradiated samples was kept below the estimated penetration depth of the electrons. No significant differences were obtained in the experiments below 90 K, but the destruction cross section at 300 K was larger by a factor of 2. The radiolysis yields and half-life doses are in good accordance with recent MeV proton experiments, which confirms that electrons in the keV range can be used to simulate the effects of cosmic rays if the whole sample is effectively irradiated. In the low temperature experiments, electron irradiation leads to the formation of residues. IR absorptions of these residues are assigned to the presence CO2, CO, OCN-, and CN- and possibly to amide bands I to III. The protection of glycine by water ice is also studied. A water ice film of ∼150 nm is found to provide efficient shielding against the bombardment of 2 keV electrons. The results of this study show also that current Monte Carlo predictions provide a good global description of electron penetration depths. The lifetimes estimated in this work for various environments ranging from the diffuse interstellar medium to the inner solar system, show that the survival of hypothetical primeval glycine from the solar nebula in present solar system bodies is not very likely. © 2015. The American Astronomical Society. All rights reserved.
    No preview · Article · Jun 2015 · The Astrophysical Journal
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    Sonia Yáñez · Pamela Hidalgo · Rubén Escribano

    Full-text · Dataset · Apr 2015
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    ABSTRACT: Oxygen Minimum Zones (OMZ’s) are expanding and intensifying as result of climate change, affecting Eastern Boundary Upwelling Systems. Local effects of vertical movements of OMZ’s that result from changes in upwelling intensity could reduce or expand the oxygenated surface layer that most zooplanktonic species inhabit in coastal areas. Using the copepods Calanus chilensis and Acartia tonsa as model organisms, an experimental test of the impact of different dissolved oxygen (DO) concentrations (between 0.5 to 5 ml L- 1) on egg production and hatching success was carry out and compared with field estimations of egg production, female and egg abundance at in Mejillones Bay(23°S). Abundance of C. chilensis was highly variability and no consistent pattern in egg production and hatching success was found across DO levels, whereas A. tonsa egg production had maximum values between 2.6 to 4.7 ml O2 L- 1 and hatching success was positively correlated with DO (r=0.75). In the field, temperature was the main factor controlling the dynamics of both species, while Chl-a and DO were also correlated with C. chilensis and A. tonsa, respectively. Principal Component Analysis showed that abundances of both copepods were controlled by temperature, stratification, OMZ depth, and Ekman transport, which together explained more than 70% of the total variance and were the main factors that modulated the populations of C. chilensis and A. tonsa in the upwelling zone of northern Chile (23°S).The differential responses of C. chilensis and A. tonsa to changes in DO concentrations associated with vertical movements of the OMZ suggest that C. chilensis may be better adapted to hypoxic conditions than A. tonsa, however both species are successful and persistent all year-round. We suggest that physiological responses of copepods could be used to evaluate population dynamics affected by the shoaling of OMZs and the repercussions to trophic food webs of eastern boundary current systems.
    No preview · Article · Mar 2015 · Journal of Marine Systems
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    ABSTRACT: Mesoscale eddies are prominent structures in the world's oceans generating a high degree of spatial and temporal heterogeneity that influences zooplankton distribution. Euphausiids (krill) are a key zooplankton group mainly inhabiting coastal upwelling areas where high productivity, advection and eddy kinetic energy (EKE) play pivotal roles in the distribution and structure of krill habitats. We analyzed the spatial distribution of the Humboldt Current krill, Euphausia mucronata, in relation to environmental variability and mesoscale circulation during the 2007 austral spring. Using net-based zooplankton samples, remotely sensed environmental conditions, multivariate analysis and generalized additive models, we described and tested the effect of oceanographic variability and mesoscale eddies on E. mucronata abundance and biomass. E. mucronata was significantly more abundant in coastal (97%) than oceanic habitats, and more abundant in cyclonic cores (mean: 76 indiv. m−2) than in surrounding waters (mean: 13-29 indiv. m−2). Abundance correlated to current and EKE fields at >10-20 cm s−1 and >50-200 cm2 s−2, respectively, and biomass correlated negatively to sea level anomaly and positively to alongshore winds. Krill abundance and biomass were also strongly coupled to both eddy dynamics and the coastal upwelling regime in spring 2007. Mesoscale eddies may doubly influence the E. mucronata population dynamic by retaining krill within them and, by advection from coastal to oligotrophic regions. This article is protected by copyright. All rights reserved.
    Full-text · Article · Mar 2015 · Journal of Geophysical Research: Oceans
  • R. Escribano · E. Bustos-Ríos · P. Hidalgo · C. E. Morales
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    ABSTRACT: Zooplankton production is a critical issue for understanding marine ecosystem structure and dynamics, however, its time-space variations are mostly unknown in most systems. In this study, estimates of copepod growth and production (CP) in the coastal upwelling and coastal transition zones off central-southern Chile (∼35–37° S) were obtained from annual cycles during a 3 year time series (2004, 2005, and 2006) at a fixed shelf station and from spring–summer surveys during the same years. C-specific growth rates (g) varied extensively among species and under variable environmental conditions; however, g values were not correlated to either near surface temperature or copepod size. Copepod biomass (CB) and CP were higher within the coastal upwelling zone (
    No preview · Article · Feb 2015 · Biogeosciences Discussions
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    S. M. Cahuin · L. A. Cubillos · R. Escribano
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    ABSTRACT: Most of the studies investigating synchrony in fluctuations of abundance of small pelagic fish have been based on catch data only, which do not describe the dynamics of populations as a relative abundance index. In this paper, catch, biomass, recruitment and recruitment rate, were used to compare synchronous changes for two stocks of anchovy (Engraulis ringens) from 1982 to 2004. One is the North Central Peru stock (NCP) and the other is the shared South Peru-Northern Chile stock (SPNC). Correlation analysis demonstrated a significant association between population time series, particularly during the growing phase of the stocks. Thus, the synchronous fluctuation pattern of the two stocks is due to the recovery phase and probably driven by density-independent effects of simultaneous favorable environmental conditions occurring in the two regions. The conclusions were: (i) both NCP and SPNC anchovy stocks are in an overall positive phase of synchrony, (ii) higher correlations in the synchronous pattern of fluctuations occurred during simultaneous increase of biomass, and (iii) short-term fluctuations were negative when the abundance of the stock was lower and/or impacted by El Niño events.
    Full-text · Article · Dec 2014 · Journal of Applied Ichthyology
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    ABSTRACT: Community structure of pelagic copepods inhabiting the coastal upwelling zone of central-southern Chile was compared between the periods 2002-2004 and 2010-2012. For both periods, 74 copepod species were identified; the Order Calanoida accounted for 68% of the total abundance. Numerically dominant species (ca. 80% of total abundance) were Paracalanus cf. indicus, Oithona similis, Calanoides patagoniensis, Drepanopus forcipatus and Acartia tonsa. Multivariate analyses showed that from the first period (2002-2004) to the second period (2010-2012), there were significant changes in the abundance of some species, the order of dominance and community size structure, although no significant changes in species richness and diversity indexes were found. The dominant species, Paracalanus cf. indicus, was numerically replaced by Drepanopus forcipatus in 2010-2012. There was also a significant decrease in total abundance of copepods during 2010–2012. The assessment of oceanographic variables revealed that colder and saltier conditions prevailed during 2010-2012, accompanied by a greater stratification of the water column because of increased upwelling intensity. Our findings suggest that increasing upwelling has been an important factor for causing changes in the copepod community structure during the past decade.
    Full-text · Article · Nov 2014 · Marine Ecology Progress Series
  • R Escribano · V Timón · O Gálvez · B Maté · M A Moreno · V J Herrero
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    ABSTRACT: The symmetric stretching vibration (breathing mode) of methane is forbidden in the infrared spectra of gases. However, it has been observed in the spectra of low-pressure ice mixtures of methane and water, studied as models for astronomical ices. We investigate the possible origin of the activation of this mode by means of solid state calculations of amorphous water (ASW) samples into which methane molecules are introduced. Activation is predicted either by the interaction of the CH4 and H2O molecules in pore walls or via a strong mode coupling that takes place between the breathing mode of CH4 and the O-H stretching mode of H2O when both vibrations coincide in frequency. These two mechanisms would be favored for low-density or high density ASW, respectively. A possible experimental observation of this activation in compact ASW is discussed.
    No preview · Article · Jul 2014 · Physical Chemistry Chemical Physics
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    ABSTRACT: Estimating growth and production rates of mesozooplankton, and copepods in particular, is important in describing flows of material and energy though pelagic systems. Over the past 30 years, the Moult Rate (MR) method has been used to estimate juvenile copepod growth rates in ∼40 papers. Yet the MR method has been shown to have serious flaws. Here we re-examine the results from the majority of published MR method studies and re-estimate growth rates using the modified Moult Rate (MMR) method, which ascribes changes in mass to the appropriate time period over which it was accrued. The MR method has typically over-estimated growth rates (on 80% of occasions) for life stages where the subsequent stage is actively moulting; the median and mean MR values are 138 and 164%, respectively, of the corrected MMR values. We were unable to correct the original data for life stages that are followed by a non-moulting stage, e.g. copepodite stage 5 to adult. We performed experiments with Calanus pacificus to estimate growth of stage C5 using an alternative method. We found that the error size and sign varied between mass type (i.e. DW, C and N). Recommendations for practical future assessments of growth in copepods are made.
    Full-text · Article · Jun 2014 · Journal of Plankton Research
  • Katty Donoso · Ruben Escribano
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    ABSTRACT: A shallow oxygen minimum zone (OMZ) in the coastal upwelling zone off Chile may vertically confine most zooplankton to a narrow (< 50 m) upper layer. From laboratory experiments, we estimated oxygen consumption of the mesozooplankton community obtained in Bay of Mejillones, northern Chile (23°S) in May 2010, December 2010 and August 2011. Mass-specific respiration rates were in the range of 8.2–24.5 μmol O2 mg dry mass− 1 day− 1, at an average temperature of 12 °C. Estimates of the mesozooplankton biomass in the water column indicated that its aerobic respiration may remove daily a maximum of about 20% of oxygen available at the base of the oxycline. Since previous work indicates that zooplankton aggregate near the base of the oxycline, the impact of aerobic respiration on oxygen content might be even stronger at this depth. Mesozooplankton respiration, along with community respiration by microorganisms near the base of the oxycline and a strongly stratified condition (limiting vertical flux of O2), are suggested as being critical factors causing and maintaining a persistent subsurface oxygen-deficient ecological barrier (BEDOX) in the upwelling zone. This BEDOX layer can have a major role in affecting and regulating zooplankton distribution and their dynamics in the highly productive coastal upwelling zone of the Humboldt Current System.
    No preview · Article · Jan 2014 · Journal of Marine Systems
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    ABSTRACT: a b s t r a c t The recruitment rate of anchovy in the Peru–Chile upwelling system was studied by testing sensitive to environmental variability when the spawning stock is low in abundance. Times series of sea surface temperature, salinity, depth of the 15 1C isotherm, the upper limit of the oxygen minimum zone, upwelling indices, the Southern Oscillation Index, and indices El Niño 1þ2 and El Niño 3.4 were summarized trough Principal Component Analysis (PCA). The first PCA (PC-I) explained 57% of variance and was related to interannual variability driven by the El Niño-Southern Oscillation. The second Principal Component explained 15% of variance and was linked to upwelling indices. Anchovy recruitment rate anomalies were correlated with PC-I scores on the basis of a 6-year-moving-window and accumulated correlation as time progressed. Signifi-cant correlation coefficients were found when the spawning stock biomass was low in abundance before 1990. Once sufficient
    Full-text · Dataset · Aug 2013
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    Johanna Medellín-Mora · Rubén Escribano

    Preview · Article · Mar 2013 · Latin American Journal of Aquatic Research
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    Full-text · Dataset · Feb 2013
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    ABSTRACT: Seasonal and inter-annual variability in population abundance, biomass, and somatic and molt production of the Humboldt Current krill, Euphausia mucronata, were studied during a monthly time series (August 2002-June 2007) at Station 18 (36º 30’ S; 73º 07’ W) off central-southern Chile. Coastal upwelling intensity was the main oceanographic process found to control E. mucronata population abundance and biomass production on seasonal and inter-annual time scales. Spawning peaks and population structure indicate that E. mucronata produces at least two generations per year. The main spawning period occurs during the austral spring when phytoplankton concentration is high. A second, less intense spawning period occurs at the end of the austral summer and early autumn. E. mucronata had a mean biomass of 100 mg C m-3 and an integrated annual secondary production of 2,432 mg C m-3 y-1, with an overall P/B ratio of 24. In May 2007, a maximum daily integrated biomass of 5 g C m-3 and total daily secondary production of 63 mg C m-3 d-1 were observed. These estimates are considerably higher than those reported for other krill species in coastal upwelling regions. Multivariate analyses indicate that upwelling-favorable winds promote high E. mucronata biomass and secondary production, but higher abundance and biomass were found during the transition periods from upwelling to downwelling conditions. Results suggest that E. mucronata has a highly efficient behavioral strategy to attain high production rates and recover rapidly from potential offshore losses due to advective processes in a highly productive coastal upwelling ecosystem.
    Full-text · Article · Feb 2013 · Marine Ecology Progress Series
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    Dataset: MBR VAR
    Victor M. Aguilera · Katty Donoso · Ruben Escribano

    Full-text · Dataset · Feb 2013
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    ABSTRACT: Egg production (EP) and egg development rate (DR) of Centropages brachiatus, Calanus chilensis and Paracalanus indicus, three abundant copepods in the Humboldt Current System, were experimentally assessed during spring-summer and autumn-winter periods between 2001 and 2012 in northern Chile (23 degrees S) and central/southern Chile (36 degrees S). EP was on average 43.3, 29.3 and 5.0 eggs female(-1)day(-1) in C. brachiatus, C. chilensis and P. indicus, respectively. C. chilensis and C. brachiatus displayed similar embryonic DR, whereas that of P. indicus was significantly faster. DR was significantly affected by season and location, being faster in the spring-summer and off northern Chile. DRs allowed estimates of temperature-dependent generation times (GT). Expected GTs for C. brachiatus and C. chilensis at mean observed temperatures in both places coincided with those derived from field studies. Estimates of GT could also explain the presence of multiple generations a year, upon continuous reproduction, and potentially in the absence of food limitation. Despite a low EP, P. indicus exhibited a high DR and expected GT in the range of 10-20 days, explaining the existence of many generations a year as reported by field studies. Our findings provide evidence to support the hypothesis that population dynamics of these species may be fundamentally controlled by temperature in the coastal upwelling zone.
    No preview · Article · Jan 2013 · Journal of Plankton Research
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    J. Medellín-Mora · R. Escribano
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    ABSTRACT: The study of zooplankton communities is very important in the context of the biology, ecology, and conservation of the marine ecosystem. However, research on zooplankton implies a highly costly process in terms of time and effort, requiring trained personnel for identification, counting and measuring of various taxonomic groups, including biomass estimates. At present, there is an increasing interest for implementing new techniques allowing automatic analyses of zooplankton by means of informatics technology and assessment of digitized images. In this work, the state of the art of some methodologies applied to digital images of zooplankton is revised describing the general methods used, such as ZooScan-ZooProcess and ZooImage, and an analysis of their results for identification, a comparison with traditional methods, and recommendations to improve the identification process. Additionally, a brief summary of the experiences with these systems is presented, focused on the analysis of spatial and temporal variability of the zooplankton community by means of its size spectrum and tests for deriving biomass estimates. Finally, a list of capacities and limitations of the methods is discussed using recent literature, as well as the perspectives of development and applications of this new technology can offer to the scientific community of the Latin American region.
    Full-text · Article · Jan 2013 · Latin American Journal of Aquatic Research

Publication Stats

3k Citations
283.25 Total Impact Points

Institutions

  • 2002-2016
    • University of Concepción
      • • Departamento de Oceanografía
      • • Departamento de Microbiología
      Ciudad de Concepcion, Biobío, Chile
  • 1977-2015
    • Instituto de Estructura de la Materia
      Madrid, Madrid, Spain
  • 1993-2010
    • Complutense University of Madrid
      Madrid, Madrid, Spain
  • 1993-2002
    • University of Antofagasta
      • Instituto de Investigaciones Oceanológicas
      Antofagasta, Region de Antofagasta, Chile
  • 1997-2001
    • Spanish National Research Council
      Madrid, Madrid, Spain
  • 1992
    • Dalhousie University
      • Department of Biology
      Halifax, Nova Scotia, Canada
  • 1987-1988
    • National Research Council Canada
      • Steacie Institute for Molecular Sciences (SIMS)
      Ottawa, Ontario, Canada
  • 1976
    • University of Reading
      • Department of Chemistry
      Reading, England, United Kingdom