Rates of summertime biological productivity in the Beaufort Gyre: A comparison between the low and record-low ice conditions of August 2011 and 2012

Stanley, Rachel H. R.; Sandwith, Zoe O.; Williams, William J.

doi:10.1016/j.jmarsys.2014.04.006

Cited by 22 publications

(26 citation statements)

References 108 publications

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“…Analysis occurred within ∼6 months of flask evacuation and 4 months of sample collection at the Woods Hole Oceanographic Institution with a Thermo Fisher Scientific MAT 253 isotope ratio mass spectrometer, following the method of Barkan and Luz (2003) with modifications as described in Stanley et al (2010Stanley et al ( , 2015.…”

Section: Tracer Injectionsmentioning

confidence: 99%

“…Biogeochemical time-series observations resolving seasonal changes in productivity are particularly scarce in the Arctic (MacGilchrist et al, 2014;Stanley et al, 2015). Measurements at Palmer Station in Antarctica show a strong seasonality in biological productivity and carbon uptake associated with changes in light, physical mixing, and grazing and demonstrate the benefits of high-frequency sampling for quantifying CO 2 uptake (Ducklow et al, 2013;Tortell et al, 2014;Goldman et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Many investigators have assumed that there is negligible gas transfer through ice and there-fore the gas transfer velocity can be linearly scaled as a function of the fraction of open water, multiplied by the open water gas transfer velocity (Takahashi et al, 2009;Legge et al, 2015;Evans et al, 2015;Stanley et al, 2015), however, this assumption is not well verified. A recent study by Butterworth and Miller (2016) concluded that gas transfer velocities in the Southern Ocean at 0-100 % ice cover approximated the expected linear relationship with ice cover, but other studies report that gas exchange is reduced or enhanced in the presence of sea ice relative to a linear scaling based on the fraction of open water, including some studies measuring higher transfer velocities in ice-covered waters than in open water (Fanning and Torres, 1991;Else et al, 2011;Papakyriakou and Miller, 2011;Rutgers van der Loeff et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…To our knowledge, this study is the first field-based experiment where the dual tracer technique is conducted in the presence of ice, and it adds to a limited number of in situ measurements of NOP and GOP during ice melt (Goldman et al, 2015;Stanley et al, 2015;Eveleth et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Tracer Injectionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Manning¹

2017

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“…To our knowledge, there are no other published field-based experiments where the dual tracer technique was used in the presence of ice, and this study adds to a limited number of in situ measurements of NOP and GOP during ice melt (Goldman et al, 2015;Stanley et al, 2015;Eveleth et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Changes in gross oxygen production, net oxygen production, and air-water gas exchange during seasonal ice melt in the Bras d'Or Lake, a Canadian estuary

Manning

Stanley

Nicholson

et al. 2017

Preprint

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Abstract. Sea ice is an important control on gas exchange and primary production in polar regions. We measured net oxygen production and gross oxygen production using near-continuous measurements of the O 2 /Ar gas ratio and discrete measurements of the triple isotopic composition of O 2 in the Bras d'Or Lake, an estuary in Nova Scotia, Canada, as the bay transitioned from ice-covered to ice-free conditions. The volumetric gross oxygen production was 5.4( +2.8 −1.6 ) mmol O 2 m −3 d −1 , similar at the beginning and end of the time-series, and likely peaked at the end of the ice melt period. Net oxygen production displayed more 5 temporal variability and the system was on average net autotrophic during ice melt and net heterotrophic following the ice melt.We performed the first field-based dual tracer release experiment in ice-covered water to quantify air-water gas exchange. The gas transfer velocity at >90 % ice cover was 6 % of the rate for nearly ice-free conditions. Published studies have shown a wide range of results for gas transfer velocity in the presence of ice, and this study indicates that gas transfer through ice is much slower than the rate of gas transfer through open water. The results also indicate that both primary producers and heterotrophs 10 are active in Whycocomagh Bay during spring while it is covered in ice.

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Annual cyclicity in export efficiency in the inner Southern California Bight

Haskell

Prokopenko

Hammond

et al. 2017

Global Biogeochemical Cycles

Self Cite

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The balance of marine autotrophy and heterotrophy regulates the ocean's ability to serve as a CO2 sink, as organic material produced by autotrophs sinks into the ocean interior to drive the biological pump. Marine ecosystems over the continental margins, especially coastal upwelling regions, account for a disproportionate amount of carbon export; thus, even small fluctuations in export in these regions can have a large impact on the global carbon cycle. In this study, we estimated the rate of gross oxygen production (GOP), stoichiometrically related to gross primary production, by combining measurements of the triple isotope composition of dissolved oxygen with estimates of vertical advection, eddy diffusion, and air‐sea gas exchange in a one‐dimensional two‐box nonsteady state model of the euphotic zone. Net oxygen production (NOP) estimates based on O2/Ar were then combined with GOP to estimate the NOP/GOP ratio, or potential export efficiency, out of the euphotic zone at the San Pedro Ocean Time‐series during an 18 month period between January 2013 and June 2014. GOP estimates ranged from 161 ± 44 to 477 ± 155 mmol m−2 d−1 during this period, peaking in May each year, and NOP/GOP ratios ranged from 0.05 ± 0.10 to 0.65 ± 0.28. The highest export efficiency occurred in late February/early March, following the onset of spring upwelling, declining as the upwelling season continued. This study demonstrates that export efficiency changes through time in this temperate coastal upwelling region on a repeated annual cycle, and the magnitude of export efficiency suggests efficient photosynthetic energy conversion by phytoplankton in spring.

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Rates of summertime biological productivity in the Beaufort Gyre: A comparison between the low and record-low ice conditions of August 2011 and 2012

Cited by 22 publications

References 108 publications

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

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

Changes in gross oxygen production, net oxygen production, and air-water gas exchange during seasonal ice melt in the Bras d'Or Lake, a Canadian estuary

Annual cyclicity in export efficiency in the inner Southern California Bight

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