Carbon:Chlorophyll ratios of Subarctic Pacific surface waters

We present optically-derived estimates of phytoplankton carbon (Cphyto) and chlorophyll a concentration (Chl) across a wide range of productivity and hydrographic regimes in the Subarctic Pacific Ocean. Our high-frequency measurements capture changes in Cphyto and Chl across regional gradients in ma...

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Bibliographic Details
Main Authors: Burt, William J, Westberry, Toby K, Behrenfeld, Michael J, Zeng, Chen, Izett, Robert W, Tortell, Philippe Daniel
Format: Dataset
Language:English
Published: PANGAEA 2018
Subjects:
Carbon/Chlorophyll a ratio
Chlorophyll a
CT
DATE/TIME
LATITUDE
LONGITUDE
Phytoplankton
biomass as carbon
Salinity
Subarctic
Subarctic_PO
Uncertainty
Underway cruise track measurements
Gulf of Alaska
Pacific
Alaska
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.886143
https://doi.org/10.1594/PANGAEA.886143
Description
Summary:We present optically-derived estimates of phytoplankton carbon (Cphyto) and chlorophyll a concentration (Chl) across a wide range of productivity and hydrographic regimes in the Subarctic Pacific Ocean. Our high-frequency measurements capture changes in Cphyto and Chl across regional gradients in macro- and micronutrient limitation, and sub-mesoscale hydrographic frontal zones. Throughout the majority of our survey region, carbon to chlorophyll ratios (Cphyto:Chl) ranged between 50-100. Lower values (10-20) were constrained to the highly productive coastal upwelling system along Vancouver Island, whereas higher estimated values (>200) were found directly off the southern British Columbia continental shelf. Further offshore, Cphyto:Chl was less variable, ranging from 50-80 in high nutrient low Chl (HNLC) waters in June, and from 80-120 in the Gulf of Alaska in July. Much of the variability in Cphyto:Chl throughout the study region could be explained by mixed layer light levels (i.e. photo-acclimation), with additional variability attributed to nutrient-controlled changes in phytoplankton growth rates in some regions. Elevated Cphyto:Chl ratios resulting from apparent nutrient stress were found in areas of low macro-nutrient concentrations. In contrast, iron-limited waters exhibited Cphyto:Chl ratios lower than predicted from the photo-acclimation model. Applying the Carbon-based production model, we derived Cphyto and Chl-based estimates of net primary productivity, which showed good coherence with independent 14C uptake measurements. Our results highlight the utility of ship-board optical data to examine phytoplankton physiological ecology and productivity in surface marine waters.

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