The annual cycle of gross primary production, net community production, and export efficiency across the North Pacific Ocean

Palevsky, Hilary I.; Quay, Paul D.; Lockwood, Deirdre Elizabeth; Nicholson, David P.

doi:10.1002/2015gb005318

Cited by 50 publications

(79 citation statements)

References 93 publications

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“…Due to the spatial variability in

O_{2}

, we were not able to determine the rate of change in Δ(

O_{2}

/Ar) with time, which is needed for a nonsteady state calculation of NOP (equation ) [ Hamme et al ., ; Tortell et al ., ; Wilson et al ., ; Palevsky et al ., ]. For example, we can calculate a linear regression of Δ(

O_{2}

/Ar) versus time over any 48 h period in Phase 2 (beginning 30 September 10:10 or later), with the 48 h period chosen to prevent diurnal cycling in

O_{2}

from biasing the slope [ Hamme et al ., ].…”

Section: Resultsmentioning

confidence: 97%

Impact of recently upwelled water on productivity investigated using in situ and incubation‐based methods in Monterey Bay

et al. 2017

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Photosynthetic conversion of CO2 to organic carbon and the transport of this carbon from the surface to the deep ocean is an important regulator of atmospheric CO2. To understand the controls on carbon fluxes in a productive region impacted by upwelling, we measured biological productivity via multiple methods during a cruise in Monterey Bay, California. We quantified net community production and gross primary production from measurements of O2/Ar and O2 triple isotopes ( 17Δ), respectively. We simultaneously conducted incubations measuring the uptake of 14C, 15NO3−, and 15NH4+, and nitrification, and deployed sediment traps. At the start of the cruise (Phase 1) the carbon cycle was at steady state and the estimated net community production was 35(10) and 35(8) mmol C m−2 d−1 from O2/Ar and 15N incubations, respectively, a remarkably good agreement. During Phase 1, net primary production was 96(27) mmol C m−2 d−1 from C uptake, and gross primary production was 209(17) mmol C m−2 d−1 from 17Δ. Later in the cruise (Phase 2), recently upwelled water with higher nutrient concentrations entered the study area, causing 14C and 15NO3− uptake to increase substantially. Continuous O2/Ar measurements revealed submesoscale variability in water mass structure and likely productivity in Phase 2 that was not evident from the incubations. These data demonstrate that O2/Ar and 15N incubation‐based NCP estimates can give equivalent results in an N‐limited, coastal system, when the nonsteady state O2 fluxes are negligible or can be quantified.

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“…Due to the spatial variability in

O_{2}

, we were not able to determine the rate of change in Δ(

O_{2}

O_{2}

/Ar) versus time over any 48 h period in Phase 2 (beginning 30 September 10:10 or later), with the 48 h period chosen to prevent diurnal cycling in

O_{2}

from biasing the slope [ Hamme et al ., ].…”

Section: Resultsmentioning

confidence: 97%

Impact of recently upwelled water on productivity investigated using in situ and incubation‐based methods in Monterey Bay

et al. 2017

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“…For example, the assumption of steady state may be violated during vigorous blooms in the early growing season (Figure ). Previous studies also observed strong seasonality in the NCP [ Bushinsky and Emerson , ; Emerson , ; Fassbender et al ., ; Ostle et al ., ; Palevsky et al ., ]. Net heterotrophy and entrainment of newly exported production back into the mixed layer, more commonly observed in the fall and winter [ Bushinsky and Emerson , ; Emerson , ; Fassbender et al ., ; Kortzinger et al ., ; Ostle et al ., ; Palevsky et al ., ], are not captured by our current algorithms.…”

Section: Discussionmentioning

confidence: 99%

Interannual variability in net community production at the Western Antarctic Peninsula region (1997–2014)

Cassar

Huang

et al. 2016

JGR Oceans

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In this study, we examined the interannual variability of net community production (NCP) in the Western Antarctic Peninsula (WAP) using in situ O2/Ar‐NCP estimates (2008–2014) and satellite data (SeaWiFS and MODIS‐Aqua) from 1997 to 2014. We found that NCP generally first peaks offshore and follows sea‐ice retreat from offshore to inshore. Annually integrated NCP (ANCP) displays an onshore‐to‐offshore gradient, with coastal and shelf regions up to 8 times more productive than offshore regions. We examined potential drivers of interannual variability in the ANCP using an Empirical Orthogonal Function (EOF) analysis. The EOF's first mode explains ∼50% of the variance, with high interannual variability observed seaward of the shelf break. The first principal component is significantly correlated with the day of sea‐ice retreat (R = −0.58, p < 0.05), as well as the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) climate indices in austral spring. Although the most obvious pathway by which the day of sea‐ice retreat influences NCP is by controlling light availability early in the growing season, we found that the effect of day of sea‐ice retreat on NCP persists throughout the growing season, suggesting that additional controls, such as iron availability, are preconditioned or correlated to the day of sea‐ice retreat.

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“…Due to the spatial variability in O 2 , we are not able to determine the rate of change in ∆(O 2 /Ar) with time, which is needed for a non-steady state calculation of NOP (Hamme et al, 2012;Tortell et al, 2014;Wilson et al, 2015;Palevsky et al, 2016a). For example, we can calculate a linear regression of ∆(O 2 /Ar) versus time over any 48 h period in Phase 2 (beginning 30 September 10:10 or later), with the 48 h period chosen to prevent diurnal cycling in O 2 from biasing the slope (Hamme et al, 2012).…”

Section: Measured At 50 M Depth; All Other Methods Integrated To the mentioning

confidence: 99%

Insight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracers

Manning¹

2017

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In this thesis, I use coastal measurements of dissolved O 2 and inert gases to provide insight into the chemical, biological, and physical processes that impact the oceanic cycles of carbon and dissolved gases. Dissolved O 2 concentration and triple isotopic composition trace net and gross biological productivity. The saturation states of inert gases trace physical processes, such as air-water gas exchange, temperature change, and mixing, that affect all gases.First, I developed a field-deployable system that measures Ne, Ar, Kr, and Xe gas ratios in water. It has precision and accuracy of 1 % or better, enables near-continuous measurements, and has much lower cost compared to existing laboratory-based methods. The system will increase the scientific community's access to use dissolved noble gases as environmental tracers.Second, I measured O 2 and five noble gases during a cruise in Monterey Bay, California. I developed a vertical model and found that accurately parameterizing bubble-mediated gas exchange was necessary to accurately simulate the He and Ne measurements. I present the first comparison of multiple gas tracer, incubation, and sediment trap-based productivity estimates in the coastal ocean. Net community production estimated from 15 NO -3 uptake and O 2 /Ar gave equivalent results at steady state. Underway O 2 /Ar measurements revealed submesoscale variability that was not apparent from daily incubations.Third, I quantified productivity by O 2 mass balance and air-water gas exchange by dual tracer ( 3 He/SF 6 ) release during ice melt in the Bras d'Or Lakes, a Canadian estuary. The gas transfer velocity at >90 % ice cover was 6 % of the rate for nearly ice-free conditions. Rates of volumetric gross primary production were similar when the estuary was completely ice-covered and ice-free, and the ecosystem was on average net autotrophic during ice melt and net heterotrophic following ice melt. I present a method for incorporating the isotopic composition of H 2 O into the O 2 isotope-based productivity calculations, which increases the estimated gross primary production in this study by 46-97 %.In summary, I describe a new noble gas analysis system and apply O 2 and inert gas observations in new ways to study chemical, biological, and physical processes in coastal waters.

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The annual cycle of gross primary production, net community production, and export efficiency across the North Pacific Ocean

Cited by 50 publications

References 93 publications

Impact of recently upwelled water on productivity investigated using in situ and incubation‐based methods in Monterey Bay

Impact of recently upwelled water on productivity investigated using in situ and incubation‐based methods in Monterey Bay

Interannual variability in net community production at the Western Antarctic Peninsula region (1997–2014)

Insight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracers

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