DISCOL: A Long-Term, Large-Scale, Disturbance-Recolonization Experiment in the Abyssal Eastern Tropical South Pacific Ocean

1990 ◽  
Author(s):  
E.J. Foell ◽  
H. Thiel ◽  
G. Schriever
Keyword(s):  
Pacific Ocean ◽  
Large Scale ◽  
South Pacific ◽  
South Pacific Ocean ◽  
Large Scale Disturbance

scholarly journals Decadal Variability in the Large-Scale Sea Surface Height Field of the South Pacific Ocean: Observations and Causes

2006 ◽  
Vol 36 (9) ◽  
pp. 1751-1762 ◽  
Author(s):  
Bo Qiu ◽  
Shuiming Chen
Keyword(s):  
Pacific Ocean ◽  
Rossby Wave ◽  
Large Scale ◽  
South Pacific ◽  
Sea Surface Height ◽  
Sea Surface ◽  
South American ◽  
The South ◽  
South Pacific Ocean ◽  
Spatially Varying

Abstract Large-scale sea surface height (SSH) changes in the extraequatorial South Pacific Ocean are investigated using satellite altimetry data of the past 12 yr. The decadal SSH signals in the 1990s were dominated by an increasing trend in the 30°–50°S band and a decreasing trend in the central South Pacific Ocean poleward of 50°S. In recent years since 2002 there has been a reversal in both of these trends. Spatially varying low-frequency SSH signals are also found in the tropical region of 10°–25°S where the decadal SSH trend is negative in the eastern basin, but positive in the western basin. To clarify the causes for these observed spatially varying SSH signals, a 1½-layer reduced-gravity model that includes the wind-driven baroclinic Rossby wave dynamics and the responses forced by SSH changes along the South American coast was adopted. The model hindcasts the spatially varying decadal trends in the midlatitude and the eastern tropical regions well. Accumulation of the wind-forced SSH anomalies along Rossby wave characteristics is found to be important for both previously reported long-term trends and their reversals in recent years. The boundary forcing associated with the time-varying SSH signals along the South American coast is crucial for understanding the observed SSH signals of all time scales in the eastern tropical South Pacific basin, but it has little impact upon the midlatitude interior SSH signals.

scholarly journals Circulation, eddies, oxygen, and nutrient changes in the eastern tropical South Pacific Ocean

Ocean Science ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 455-470 ◽  
Author(s):  
R. Czeschel ◽  
L. Stramma ◽  
R. A. Weller ◽  
T. Fischer
Keyword(s):  
Pacific Ocean ◽  
Large Scale ◽  
Current System ◽  
Oxygen Deficiency ◽  
South Pacific ◽  
Upper Ocean ◽  
Net Community Production ◽  
Equatorial Undercurrent ◽  
South Pacific Ocean ◽  
Eastern Equatorial Pacific

Abstract. A large subsurface oxygen deficiency zone is located in the eastern tropical South Pacific Ocean (ETSP). The large-scale circulation in the eastern equatorial Pacific and off the coast of Peru in November/December 2012 shows the influence of the equatorial current system, the eastern boundary currents, and the northern reaches of the subtropical gyre. In November 2012 the equatorial undercurrent (EUC) is centered at 250 m depth, deeper than in earlier observations. In December 2012, the equatorial water is transported southeastward near the shelf in the Peru–Chile undercurrent (PCUC) with a mean transport of 1.4 Sv. In the oxygen minimum zone (OMZ), the flow is overlaid with strong eddy activity on the poleward side of the OMZ. Floats with parking depth at 400 m show fast westward flow in the mid-depth equatorial channel and sluggish flow in the OMZ. Floats with oxygen sensors clearly show the passage of eddies with oxygen anomalies. The long-term float observations in the upper ocean lead to a net community production estimate at about 18° S of up to 16.7 mmol C m−3 yr−1 extrapolated to an annual rate and 7.7 mmol C m−3 yr−1 for the time period below the mixed layer. Oxygen differences between repeated ship sections are influenced by the Interdecadal Pacific Oscillation (IPO), by the phase of El Niño, by seasonal changes, and by eddies, and hence have to be interpreted with care. At and south of the Equator the decrease in oxygen in the upper ocean since 1976 is related to an increase in nitrate, phosphate, and in part silicate.

scholarly journals Circulation, eddies, oxygen and nutrient changes in the eastern tropical South Pacific Ocean

2014 ◽  
Vol 11 (5) ◽  
pp. 2205-2243
Author(s):  
R. Czeschel ◽  
L. Stramma ◽  
R. A. Weller ◽  
T. Fischer
Keyword(s):  
Pacific Ocean ◽  
Large Scale ◽  
Current System ◽  
Oxygen Deficiency ◽  
South Pacific ◽  
Upper Ocean ◽  
Net Community Production ◽  
Equatorial Undercurrent ◽  
South Pacific Ocean ◽  
Eastern Equatorial Pacific

Abstract. A large, subsurface oxygen deficiency zone is located in the eastern tropical South Pacific Ocean (ETSP). The large-scale circulation in the eastern equatorial Pacific and off Peru in November/December 2012 shows the influence of the equatorial current system, the eastern boundary currents, and the northern reaches of the subtropical gyre. In November 2012 the Equatorial Undercurrent is centered at 250 m depth, deeper than in earlier observations. In December 2012 the equatorial water is transported southeastward near the shelf in the Peru-Chile Undercurrent with a mean transport of 1.6 Sv. In the oxygen minimum zone (OMZ) the flow is overlaid with strong eddy activity on the poleward side of the OMZ. Floats with parking depth at 400 m show fast westward flow in the mid-depth equatorial channel and sluggish flow in the OMZ. Floats with oxygen sensors clearly show the passage of eddies with oxygen anomalies. The long-term float observations in the upper ocean lead to a net community production estimate at about 18° S of up to 16.7 mmol C m−3 yr1 extrapolated to an annual rate and 7.7 mmol C m−3 yr−1 for the time period below the mixed layer. Oxygen differences between repeated ship sections are influenced by the Interdecadal Pacific Oscillation, by the phase of El Niño, by seasonal changes, and by eddies and hence have to be interpreted with care. At and south of the equator the decrease in oxygen in the upper ocean since 1976 is related to an increase in nitrate, phosphate, and in part in silicate.

Carbon monoxide in the South Pacific Ocean

Tellus ◽  
1974 ◽  
Vol 26 (1-2) ◽  
pp. 136-142 ◽  
Author(s):  
J. W. Swinnerton ◽  
R. A. Lamontagne
Keyword(s):  
Carbon Monoxide ◽  
Pacific Ocean ◽  
South Pacific ◽  
The South ◽  
South Pacific Ocean

Daily accumulation rates of marine litter on the shores of Rapa Nui (Easter Island) in the South Pacific Ocean

2021 ◽  
Vol 169 ◽  
pp. 112535
Author(s):  
Martin Thiel ◽  
Bárbara Barrera Lorca ◽  
Luis Bravo ◽  
Iván A. Hinojosa ◽  
Hugo Zeballos Meneses
Keyword(s):  
Pacific Ocean ◽  
South Pacific ◽  
Easter Island ◽  
Accumulation Rates ◽  
The South ◽  
Rapa Nui ◽  
Marine Litter ◽  
South Pacific Ocean

scholarly journals Programmed cell death in diazotrophs and the fate of organic matter in the western tropical South Pacific Ocean during the OUTPACE cruise

2018 ◽  
Vol 15 (12) ◽  
pp. 3893-3908 ◽  
Author(s):  
Dina Spungin ◽  
Natalia Belkin ◽  
Rachel A. Foster ◽  
Marcus Stenegren ◽  
Andrea Caputo ◽  
...  
Keyword(s):  
Cell Death ◽  
Organic Matter ◽  
Pacific Ocean ◽  
Programmed Cell Death ◽  
South Pacific ◽  
Sediment Traps ◽  
Vertical Flux ◽  
Filamentous Cyanobacterium ◽  
Chl A ◽  
South Pacific Ocean

Abstract. The fate of diazotroph (N2 fixers) derived carbon (C) and nitrogen (N) and their contribution to vertical export of C and N in the western tropical South Pacific Ocean was studied during OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment). Our specific objective during OUTPACE was to determine whether autocatalytic programmed cell death (PCD), occurring in some diazotrophs, is an important mechanism affecting diazotroph mortality and a factor regulating the vertical flux of organic matter and, thus, the fate of the blooms. We sampled at three long duration (LD) stations of 5 days each (LDA, LDB and LDC) where drifting sediment traps were deployed at 150, 325 and 500 m depth. LDA and LDB were characterized by high chlorophyll a (Chl a) concentrations (0.2–0.6 µg L−1) and dominated by dense biomass of the filamentous cyanobacterium Trichodesmium as well as UCYN-B and diatom–diazotroph associations (Rhizosolenia with Richelia-detected by microscopy and het-1 nifH copies). Station LDC was located at an ultra-oligotrophic area of the South Pacific gyre with extremely low Chl a concentration (∼ 0.02 µg L−1) with limited biomass of diazotrophs predominantly the unicellular UCYN-B. Our measurements of biomass from LDA and LDB yielded high activities of caspase-like and metacaspase proteases that are indicative of PCD in Trichodesmium and other phytoplankton. Metacaspase activity, reported here for the first time from oceanic populations, was highest at the surface of both LDA and LDB, where we also obtained high concentrations of transparent exopolymeric particles (TEP). TEP were negatively correlated with dissolved inorganic phosphorus and positively coupled to both the dissolved and particulate organic carbon pools. Our results reflect the increase in TEP production under nutrient stress and its role as a source of sticky carbon facilitating aggregation and rapid vertical sinking. Evidence for bloom decline was observed at both LDA and LDB. However, the physiological status and rates of decline of the blooms differed between the stations, influencing the amount of accumulated diazotrophic organic matter and mass flux observed in the traps during our experimental time frame. At LDA sediment traps contained the greatest export of particulate matter and significant numbers of both intact and decaying Trichodesmium, UCYN-B and het-1 compared to LDB where the bloom decline began only 2 days prior to leaving the station and to LDC where no evidence for bloom or bloom decline was seen. Substantiating previous findings from laboratory cultures linking PCD to carbon export in Trichodesmium, our results from OUTPACE indicate that nutrient limitation may induce PCD in high biomass blooms such as displayed by Trichodesmium or diatom–diazotroph associations. Furthermore, PCD combined with high TEP production will tend to facilitate cellular aggregation and bloom termination and will expedite vertical flux to depth.

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