Oxygenation episodes on the continental shelf of central Peru: Remote forcing and benthic ecosystem response

Gutiérrez, Dimitri; Enríquez, Edgardo; Purca, Sara; Quipúzcoa, Luis; Marquina, Robert; Flores, Georgina; Graco, Michelle

doi:10.1016/j.pocean.2008.10.025

Cited by 149 publications

(203 citation statements)

References 39 publications

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“…Very low EP coincided with periods of warm water masses and low chlorophyll concentrations (not shown). These conditions were established, for example, in late 1998 during the strongly positive ENSO (Gutiérrez et al, 2008;Quiñones et al, 2010). The EP data were then used to determine the organic carbon rain rate to the seafloor (RRPOC).…”

Section: Poc Rain Rate (Rrpoc)mentioning

confidence: 99%

“…(Gallardo, 1977;Henrichs and Farrington, 1984;Schulz et al, 1996;Gutiérrez et al, 2008). These bacteria glide vertically through the sediments to access sulfide which they oxidize using nitrate stored within intracellular vacuoles (Jørgensen and Gallardo, 1999).…”

Section: Site Descriptionmentioning

confidence: 99%

“…Biological oxidation of sulfide is a major sink for sulfide in Peruvian shelf sediments (Bohlen et al, 2011;Dale et al, 2016). Bacterial biomass can be diminished if electron acceptors in the bottom water are depleted or if large amounts of organic matter are deposited on the sea bed (Gutiérrez et al, 2008). Consequently, at these times, sulfide is able to bypass the microbial filter and escape to the bottom water (Schunck et al, 2013;Sommer et al, 2016).…”

Section: Site Descriptionmentioning

confidence: 99%

“…Concentrations of dissolved oxygen and nutrients (O 2 , NO − 3 , NO − 2 ) in the water column at the IMARPE time-series station show enormous temporal variability that cannot be explained by seasonality alone (Gutiérrez et al, 2008;Graco et al, 2016). Concentrations often range by several tens of micromolar on a monthly basis.…”

Section: Bottom Water Chemistrymentioning

confidence: 99%

“…Primary productivity ranges from 1.8 to 5.2 g C m −2 d −1 (Pennington et al, 2006;Quiñones et al, 2010) and leads to a permanent oxygen minimum zone (OMZ) where dissolved oxygen concentrations are essentially zero (Thamdrup et al, 2012;Ulloa et al, 2012). On the shelf, however, bottom water redox conditions can be highly variable as a result of respiration in the water column plus the interaction of climatic variability and equatorial forcing associated with El Niño events and the passage of coastal trapped waves (Gutiérrez et al, 2008;Graco et al, 2016). This rather extreme setting should lead to strong and variable feedbacks between the sediment and water column.…”

Section: Introductionmentioning

confidence: 99%

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Strong and Dynamic Benthic-Pelagic Coupling and Feedbacks in a Coastal Upwelling System (Peruvian Shelf)

2017

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Monthly time-series data (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)) of bottom water oxygen, nitrate and nitrite concentrations from the outer shelf (150 m water depth) in the oxygen minimum zone offshore Peru were coupled to a layered biogeochemical sediment model to investigate benthic-pelagic coupling over multi-annual time scales. The model includes the mineralization of four reactive pools of particulate organic carbon (POC) with lifetimes of 0.13, 1.3, 20, and 1700 year that were constrained using empirical data. Total POC rain rates to the seafloor were derived from satellite based estimates of primary production. Solute fluxes and concentrations in sediment porewater showed highly dynamic behavior over the course of a typical year. Conversion of fixed N to N 2 by denitrification varied from 1.1 mmol m −2 d −1 of N in winter to 1.8 mmol m −2 d −1 of N in summer with a long term mean N loss for the shelf of 1.5 mmol m −2 d −1 of N. Fixed N loss across the whole time-series agreed very well with a previously-published vertically-integrated sediment model for coupling the benthic and pelagic N cycle in regional and global models. Dissimilatory nitrate reduction to ammonium (DNRA) emerges as a major process in the benthic N cycle, producing on average 1.9 mmol m −2 d −1 of ammonium: more than twice the rate of ammonification of organic nitrogen. The model predicts sulfide emissions from the sediment of up to 1 mmol m −2 d −1 when POC rain rate exceeds 20 mmol m −2 d −1 , in agreement with past observations of benthic sulfide fluxes and sulfide plume distributions in the water column. This study demonstrates that sediments on the Peruvian shelf are not static repositories that are independent of changes taking place in the water column. Our results strongly suggest the shelf sediments must exert an important feedback on biogeochemical processes in the overlying waters, and should be considered in regional model studies.

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Section: Poc Rain Rate (Rrpoc)mentioning

confidence: 99%

Section: Site Descriptionmentioning

confidence: 99%

Section: Site Descriptionmentioning

confidence: 99%

Section: Bottom Water Chemistrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Strong and Dynamic Benthic-Pelagic Coupling and Feedbacks in a Coastal Upwelling System (Peruvian Shelf)

2017

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The formation of a subsurface anticyclonic eddy in the Peru‐Chile Undercurrent and its impact on the near‐coastal salinity, oxygen, and nutrient distributions

et al. 2016

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The formation of a subsurface anticyclonic eddy in the Peru‐Chile Undercurrent (PCUC) in January and February 2013 is investigated using a multiplatform four‐dimensional observational approach. Research vessel, multiple glider, and mooring‐based measurements were conducted in the Peruvian upwelling regime near 12°30'S. The data set consists of >10,000 glider profiles and repeated vessel‐based hydrography and velocity transects. It allows a detailed description of the eddy formation and its impact on the near‐coastal salinity, oxygen, and nutrient distributions. In early January, a strong PCUC with maximum poleward velocities of ∼0.25 m/s at 100–200 m depth was observed. Starting on 20 January, a subsurface anticyclonic eddy developed in the PCUC downstream of a topographic bend, suggesting flow separation as the eddy formation mechanism. The eddy core waters exhibited oxygen concentration of <1 μmol/kg, an elevated nitrogen deficit of ∼17 μmol/L, and potential vorticity close to zero, which seemed to originate from the bottom boundary layer of the continental slope. The eddy‐induced across‐shelf velocities resulted in an elevated exchange of water masses between the upper continental slope and the open ocean. Small‐scale salinity and oxygen structures were formed by along‐isopycnal stirring, and indications of eddy‐driven oxygen ventilation of the upper oxygen minimum zone were observed. It is concluded that mesoscale stirring of solutes and the offshore transport of eddy core properties could provide an important coastal open ocean exchange mechanism with potentially large implications for nutrient budgets and biogeochemical cycling in the oxygen minimum zone off Peru.

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ENSO Atmospheric Teleconnections and Their Response to Greenhouse Gas Forcing

Yeh

Cai

Min

et al. 2018

Reviews of Geophysics

412

295

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El Niño and Southern Oscillation (ENSO) is the most prominent year‐to‐year climate fluctuation on Earth, alternating between anomalously warm (El Niño) and cold (La Niña) sea surface temperature (SST) conditions in the tropical Pacific. ENSO exerts its impacts on remote regions of the globe through atmospheric teleconnections, affecting extreme weather events worldwide. However, these teleconnections are inherently nonlinear and sensitive to ENSO SST anomaly patterns and amplitudes. In addition, teleconnections are modulated by variability in the oceanic and atmopsheric mean state outside the tropics and by land and sea ice extent. The character of ENSO as well as the ocean mean state have changed since the 1990s, which might be due to either natural variability or anthropogenic forcing, or their combined influences. This has resulted in changes in ENSO atmospheric teleconnections in terms of precipitation and temperature in various parts of the globe. In addition, changes in ENSO teleconnection patterns have affected their predictability and the statistics of extreme events. However, the short observational record does not allow us to clearly distinguish which changes are robust and which are not. Climate models suggest that ENSO teleconnections will change because the mean atmospheric circulation will change due to anthropogenic forcing in the 21st century, which is independent of whether ENSO properties change or not. However, future ENSO teleconnection changes do not currently show strong intermodel agreement from region to region, highlighting the importance of identifying factors that affect uncertainty in future model projections.

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Oxygenation episodes on the continental shelf of central Peru: Remote forcing and benthic ecosystem response

Cited by 149 publications

References 39 publications

Strong and Dynamic Benthic-Pelagic Coupling and Feedbacks in a Coastal Upwelling System (Peruvian Shelf)

Strong and Dynamic Benthic-Pelagic Coupling and Feedbacks in a Coastal Upwelling System (Peruvian Shelf)

The formation of a subsurface anticyclonic eddy in the Peru‐Chile Undercurrent and its impact on the near‐coastal salinity, oxygen, and nutrient distributions

ENSO Atmospheric Teleconnections and Their Response to Greenhouse Gas Forcing

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