Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 13, issue 4
Biogeosciences, 13, 943-959, 2016
https://doi.org/10.5194/bg-13-943-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 13, 943-959, 2016
https://doi.org/10.5194/bg-13-943-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 19 Feb 2016

Research article | 19 Feb 2016

Uncertainty and sensitivity in optode-based shelf-sea net community production estimates

Tom Hull1,2, Naomi Greenwood1,2, Jan Kaiser2, and Martin Johnson1,2 Tom Hull et al.
  • 1Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, UK
  • 2Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UK

Abstract. Coastal seas represent one of the most valuable and vulnerable habitats on Earth. Understanding biological productivity in these dynamic regions is vital to understanding how they may influence and be affected by climate change. A key metric to this end is net community production (NCP), the net effect of autotrophy and heterotrophy; however accurate estimation of NCP has proved to be a difficult task. Presented here is a thorough exploration and sensitivity analysis of an oxygen mass-balance-based NCP estimation technique applied to the Warp Anchorage monitoring station, which is a permanently well-mixed shallow area within the River Thames plume. We have developed an open-source software package for calculating NCP estimates and air–sea gas flux. Our study site is identified as a region of net heterotrophy with strong seasonal variability. The annual cumulative net community oxygen production is calculated as (−5±2.5) mol m−2 a−1. Short-term daily variability in oxygen is demonstrated to make accurate individual daily estimates challenging. The effects of bubble-induced supersaturation is shown to have a large influence on cumulative annual estimates and is the source of much uncertainty.

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We explore the estimation of NCP using an oxygen time series from a surface mooring located in the River Thames plume. Our study site is identified as a region of net heterotrophy with strong seasonal variability. Short-term daily variability in oxygen and horizontal advection is demonstrated to make accurate estimates challenging. The effects of bubble-induced supersaturation is shown to have a large influence on cumulative annual estimates.
We explore the estimation of NCP using an oxygen time series from a surface mooring located in...
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