Siliceous microorganisms in the upwelling center off Concepción, Chile (36°S): Preservation in surface sediments and downcore fluctuations during the past ∼150years

Sánchez, Gloria Elena Cruz; Lange, Carina B.; González, Humberto E.; Vargas, Gabriel; Muñoz, Práxedes; Cisternas, Carolina; Pantoja, Silvio

doi:10.1016/j.pocean.2011.07.014

Cited by 19 publications

(18 citation statements)

References 52 publications

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“…6 and 16) and ITE‐1 zones compared with the coastal zone, where their contributions were similar to those of autotrophic/mixotrophic dinoflagellates (Figures 9a and 9b). Among the numerically dominant diatom species (>100 × 10 6 cells m −2 at any station), the centric and chain‐forming Skeletonema sp., Chaetoceros debilis , and Thalassiosira anguste‐lineata (Figures 9c and 9d) are usually found in the coastal waters of the region of study (Anabalón et al, ; González et al, ; Sánchez et al, ). The highest abundances of these taxa were found mostly in both FRN‐1 and ITE‐1, as was the case of the other dominant taxa, including C. convolutus and the pennate Pseudo‐nitzschia delicatissima and P. pseudodelicatissima (Figures 9e and 9f).…”

Section: Resultsmentioning

confidence: 94%

“…(Figures 9i and 9j) were concentrated in the ITE‐1 zone, whereas Fragilariopsis doliolus was distributed in both the FRN‐1 and ITE‐1 zones (Figures i and j). The latter species has been found in oligotrophic oceanic waters of the South Pacific (Gómez et al, ) but in very low numbers in the upwelling system off Concepción (Sánchez et al, ). Guinardia delicatula (Figures 9g and 9h) was part of the community in the FRN‐1 and ITE‐1 zones but was absent from the coastal zone although it is a nondominant component in coastal waters off Valparaíso and Concepción (Gómez et al, ; Sánchez et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…Pseudo‐nitzschia species have been reported to be a dominant component in the CTZ off central Chile (Gómez et al, ; Menschel et al, ) and in oligotrophic waters of the tropical central Pacific (Gómez et al, ), but they are not usually dominant in the coastal upwelling waters off Concepción (Anabalón et al, ; Sánchez et al, ). In general, Pseudo‐nitzschia species are known to have lower Si requirements and weakly silicified frustules compared to other diatoms, in contrast to the genera which are common in coastal upwelling zones (Sommer, ).…”

Section: Resultsmentioning

confidence: 99%

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Front‐Eddy Influence on Water Column Properties, Phytoplankton Community Structure, and Cross‐Shelf Exchange of Diatom Taxa in the Shelf‐Slope Area off Concepción (∼36–37°S)

et al. 2017

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In eastern boundary current systems (EBCSs), submesoscale to mesocale variability contributes to cross‐shore exchanges of water properties, nutrients, and plankton. Data from a short‐term summer survey and satellite time series (January–February 2014) were used to characterize submesoscale variability in oceanographic conditions and phytoplankton distribution across the coastal upwelling and coastal transition zones north of Punta Lavapié, and to explore cross‐shelf exchanges of diatom taxa. A thermohaline front (FRN‐1) flanked by a mesoscale anticyclonic intrathermocline eddy (ITE‐1), or mode‐water eddy, persisted during the time series and the survey was undertaken during a wind relaxation event. At the survey time, ITE‐1 contributed to an onshore intrusion of warm oceanic waters (southern section) and an offshore advection of cold coastal waters (northern section), with the latter forming a cold, high chlorophyll‐a filament. In situ phytoplankton and diatom biomasses were highest at the surface in FRN‐1 and at the subsurface in ITE‐1, whereas values in the coastal zone were lower and dominated by smaller cells. Diatom species typical of the coastal zone and species dominant in oceanic waters were both found in the FRN‐1 and ITE‐1 interaction area, suggesting that this mixture was the result of both offshore and onshore advection. Overall, front‐eddy interactions in EBCSs could enhance cross‐shelf exchanges of coastal and oceanic plankton, as well as sustain phytoplankton growth in the slope area through localized upward injections of nutrients in the frontal zone, combined with ITE‐induced advection and vertical nutrient inputs to the surface layer.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Front‐Eddy Influence on Water Column Properties, Phytoplankton Community Structure, and Cross‐Shelf Exchange of Diatom Taxa in the Shelf‐Slope Area off Concepción (∼36–37°S)

et al. 2017

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“…Wind intensity, PCC and ENSO dynamics are the main factors controlling productivity changes along the Chilean margin north of 38°S (Fiedler, ; Aguirre et al ., , 2014). Periods of elevated productivity are interpreted as ‘summer‐like’ conditions with relatively cooler marine waters, stronger water circulation (more oxic conditions at the bottom), and increased southerly winds that are coherent with higher mixing processes and upwelling frequency (Sánchez et al ., ).…”

Section: Study Areamentioning

confidence: 98%

A 7000‐year high‐resolution lake sediment record from coastal central Chile (Lago Vichuquén, 34°S): implications for past sea level and environmental variability

Frugone-Álvarez

Latorre

Giralt

et al. 2017

J Quaternary Science

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We present a 7‐ka environmental reconstruction based on sedimentological and geochemical data from Lago Vichuquén, a coastal eutrophic lake in central Chile (34°48′S, 72°03′ W, 4 m a.s.l.). A relatively shallow and restricted marine environment with low productivity, high detrital input and dominant anoxic conditions in the Vichuquén Basin occurred from 7.0 to 6.5 cal ka BP. Rapid onset of a Holocene marine transgression at 6.5 cal ka BP favoured deeper and more biologically productive environments that existed until 2.8 cal ka BP. Bioproductivity changes during the mid‐Holocene (6.5–4.2 cal ka BP) were related to upwelling dynamics controlled by the intensity of the South‐east Pacific Anticyclone (SPA). Periods with lower organic productivity and dominant anoxic conditions reflect an increased intensity of SPA (increased upwelling) and decreased precipitation. A shift at ∼4.0 cal ka BP reflects the onset of modern Southern Westerly Winds and El Niño‐Southern Oscillation patterns. Tectonic uplifting and geormorphological activity (dune advancement) are possible reasons behind the Vichuquén Basin closure at ∼1.2 cal ka BP, leading to a low bioproductivity lacustrine environment which has developed until the present. Copyright © 2017 John Wiley & Sons, Ltd.

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“…4d), coincident with a maximum in total diatoms and Chaetoceros diatom counts (Mix et al, 2003; Fig 4c), and concurrent with the peak in MARTOC. Chaetoceros diatoms are generally associated with upwelling (e.g., Abrantes, 1988;5 Abrantes and Moita, 1999), and also for the Peru-Chile upwelling system, the diatom genus Chaetoceros is thought to dominate the diatom community during upwelling conditions (e.g., Anabalón et al, 2007;Schrader and Sorknes, 1991;Romero et al, 2001;Vargas et al, 2004;Abrantes et al, 2007;González et al, 2007;Sanchez et al, 2012). Therefore, the high abundance of Chaetoceros diatoms at ~100 ka suggests that there was a peak in upwelling intensity around this time, possibly related to the southern position of the subtropical high pressure system and associated upwelling-inducing winds.…”

Section: Productivitymentioning

confidence: 99%

A Late Quaternary climate record based on long chain diol proxies from the Chilean margin

Bar¹,

Stolwijk²,

McManus³

et al. 2018

Preprint

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Abstract. The primary focus of this study is to test the applicability of different paleoenvironmental proxies based on long chain diols, i.e., the LDI as proxy for past SST, the Diol Index as indicator of past upwelling conditions and the NDI as quantitative proxy for nitrate and phosphate concentrations in seawater. The proxies were analyzed in marine sediments recovered at ODP Site 1234, located within the Peru-Chile upwelling system, with a ~ 2 kyr resolution, covering the last 150 kyrs, i.e., encompassing several glacial and interglacial periods. We also generated TEXH86 and UK´37 temperature and planktonic δ18O records, as well as TOC and accumulation rates (ARs) of TOC and lipid biomarkers (i.e., C37 alkenones, GDGTs, dinosterol and loliolide) to reconstruct past phytoplankton production. The LDI-derived SST record co-varies with TEXH86- and UK´37-derived SST records as well as with the planktonic δ18O record, implying that the LDI reflects past SST variations at this site. TOC and phytoplankton AR records indicate increased export production during the Last Interglacial (MIS 5), simultaneous with a peak in the abundance of preserved Chaetoceros diatoms, suggesting intensified upwelling during this period. The Diol Index is relatively low during the upwelling period, but peaks before and after this period, suggesting that Proboscia diatoms were more dominant before and after the period of upwelling. The NDI reveals the same variations as the Diol Index suggesting that the input of nitrate and phosphate was minimal during upwelling, which is unrealistic. We suggest that the Diol Index should perhaps be considered as an indicator for Proboscia (multiple species) productivity instead of upwelling per se, whereas the NDI likely reflects Proboscia alata productivity, and might therefore not be suitable as a more general paleonutrient proxy.

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Siliceous microorganisms in the upwelling center off Concepción, Chile (36°S): Preservation in surface sediments and downcore fluctuations during the past ∼150years

Cited by 19 publications

References 52 publications

Front‐Eddy Influence on Water Column Properties, Phytoplankton Community Structure, and Cross‐Shelf Exchange of Diatom Taxa in the Shelf‐Slope Area off Concepción (∼36–37°S)

Front‐Eddy Influence on Water Column Properties, Phytoplankton Community Structure, and Cross‐Shelf Exchange of Diatom Taxa in the Shelf‐Slope Area off Concepción (∼36–37°S)

A 7000‐year high‐resolution lake sediment record from coastal central Chile (Lago Vichuquén, 34°S): implications for past sea level and environmental variability

A Late Quaternary climate record based on long chain diol proxies from the Chilean margin

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